Yale Psychiatry Grand Rounds: September 24, 2021

September 24, 2021

Aghajanian Lecture: "New Insights Into Psychedelic Drug Actions"

Bryan Roth, MD, PhD, Distinguished Professor, University of North Carolina Department of Pharmacology; Research Professor, University of North Carolina Department of Psychiatry

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00:00Uhm? First, at as you've probably gathered,
00:04it's tremendous pleasure to
00:06welcome our our speaker,
00:07who will be introduced by somebody
00:09else but Brian and I go back.
00:11I think, to residency days and.
00:15And it's great to have you here today.
00:17Today we're going to be celebrating the
00:20the annual George K Agajanian lecture.
00:22Here is George hard at work.
00:26In earlier days. This is George.
00:30It's the early earliest picture that
00:32I have which is a picture of George in
00:351971 and with the department faculty.
00:37He was born in Beirut, Lebanon.
00:40He went to college and Cornell.
00:42He graduated from Yale Medical School
00:44in 1958 and attended the residency.
00:48He was in EU S Army core and then rose
00:53the ranks of Yale faculty becoming
00:56the foundation's fund professor
00:59and ultimately professor emeritus.
01:01If you look closely at this picture,
01:04you see not only George,
01:05but you also see George Henninger John
01:08Flynn for whom the Flynn lecture is named.
01:12And of course,
01:13Steve Bunny and George and Steve.
01:17George Heneghan Stevonnie are also
01:19with us today, so it's a it's great.
01:23So in in medical school,
01:25George became connected to a
01:30mentee of Daniel X Friedman,
01:33charismatic, trailblazing,
01:35innovator in biological psychiatry,
01:38who led the Biological psychiatry group
01:41at Yale from the 50s until he left in
01:44the mid 60s and George's first paper.
01:47As far as I can tell,
01:49was on the topic of related to the
01:51topic of our lecture today, which is.
01:54The actions of psychedelic drugs,
01:57which this is when he was a medical student,
02:00his first medical school medical
02:02student paper, of course,
02:04appeared in science.
02:06Uhm,
02:07and and George pursued the psychedelic
02:09drugs throughout his career as a
02:12Reece area of research in in 1968.
02:16He recorded the effects of psychedelic
02:19drugs on the activity of serotonin neurons.
02:23I suspect he was the first scientist to
02:26record the activity of serotonin neurons,
02:29and he said one explanation for this
02:33common behavioral effect of LSD.
02:35In addition.
02:36Two suppressing raffey activity
02:38was that LSD acted like serotonin
02:42at a postsynaptic site in 1968.
02:45That postsynaptic site was not clear,
02:48but in 1979, as he continued to study it,
02:53which just happens to be the same year that,
02:56through reset.
02:57Radio receptor assays,
02:59the serotonin receptor,
03:01serotonin 2 receptors identified
03:03was that physiologically using
03:05facial motor neuron.
03:07Citation he using Physiology,
03:09found a second site for serotonin
03:13that was facilitated excitatory
03:15inputs and was blocked by methyl
03:18surgilight which we would of course
03:20now call a serotonin 2A receptor.
03:25But George was not only a uh,
03:28a, uh? Involved in.
03:34Serotonin neurons he mentored
03:36Steve Bunny and they were the first
03:40to record from dopamine neurons.
03:44And here is Steve and George
03:48together playing with the amplifiers.
03:50Obviously doing something with with
03:53their with their rig there in the lab.
03:56Uhm and then came, uhm, uh? Uh.
04:02Another Seminole paper, this time
04:06one of the first studies may be the
04:08first study to record from Norwich
04:10in Ergic neurons in the locus through list,
04:13and this was an incredibly Seminole
04:15study where he showed that morphine
04:18suppressed the locus release but also a
04:21spare tone and agonist Clonidine could
04:24suppress locus neurons that are activated
04:27as a result of opiate withdrawal.
04:30So you could suppress.
04:32Opiate withdrawal related activation
04:33of the locust with morphine or with
04:36the non opiate Clonidine and this
04:40led to the first rational testing.
04:43If you will mechanistic testing of a
04:46drug in psychiatry as a treatment which
04:49was the identification of Clonidine
04:52as a treatment for opiate withdrawal.
04:54When I say rationally mean whether a
04:58specific signaling mechanism was high.
05:00Related hypothesis.
05:01Was tested and this study appeared in 78.
05:05We actually was a huge inspiration
05:07to me and and one of the reasons
05:10that I ended up coming to Yale.
05:12But George has been an innovator
05:16throughout his career and in some
05:20ways his critical role in establishing
05:24mechanisms associated with rapid
05:27antidepressant effects of CADA mean
05:30in the Seminole Science paper from
05:33George and and the late Run Doom,
05:37and who we who we all miss a great deal and.
05:41And we had the pleasure.
05:43Of celebrating Georges career.
05:45In fact, the two Georges in 2014.
05:50And this was the speakers from that from
05:55that invitation in that that celebration,
05:58I would have to say,
06:00looking back on that you
06:02you might legitimately ask,
06:04where's the diversity here in this list?
06:08And I think hindsight is really important.
06:11It probably would have a different,
06:14somewhat different group if we
06:15were to do it again.
06:16So but this is this is a wonderful day.
06:21A great group of speakers and great to
06:24be together with everybody at that time.
06:28I just want to highlight that that
06:30George is not only a Seminole scientist,
06:33but also an incredibly important collaborator
06:38and mentor and important to many,
06:41many careers, including my own.
06:44Uhm,
06:44and of course he won many many honors,
06:47including the Lieber Prize from
06:48NARSAD is a member of the Institute
06:51of Medicine and received the Axelrod
06:53Award for mentorship from the AC NP.
06:55So a brief run through
07:00A RR career of George George.
07:04I didn't see whether you're on the line.
07:06I'm assuming you are and just say,
07:09once again, how deeply we appreciate all
07:12that you've brought to us individually and.
07:14US as an apartment and we're thrilled to have
07:17a lecture to celebrate your contributions
07:19to science and to the department.
07:21So I'll I'll stop it at that point and and
07:26pass it on to others who are continuing.
07:29The introduction. Marina thanks.
07:34Well, thank you for starting
07:36us off John. I won't
07:40share my screen because I think all
07:42of us have now seen Dr Agajanian's
07:45photo and I know you'll see it again.
07:48So I want to start by introducing Dr Roth.
07:51Thank you for being with us.
07:54Quick background doctor.
07:55Roth received his undergraduate
07:57degree in Biology,
07:58Biology and chemistry and then his MD,
08:00PhD before he went on to work at the
08:03NIH Lab of Preclinical Pharmacology,
08:07and he then went back and completed his
08:10residency in psychiatry at Stanford and then
08:13after 15 years at Case Western Reserve,
08:16he moved to UNC Chapel Hill in 2006,
08:18and he's currently the Michael ******
08:21Distinguished professor of Protein
08:23Therapeutics and Translational Proteomics.
08:25In the Department of Pharmacology,
08:26and I must say that is the most specific
08:29named chair that I've ever heard.
08:30I really like that.
08:32Uhm, he has joint appointments also in
08:35chemical biology and medicinal chemistry,
08:37which really shows how important
08:39his basic work is to translation
08:41into treatment and he is.
08:43This has been a theme of his
08:45work throughout his career.
08:46He's really pushed the boundaries of how
08:48we look at the structure of G protein,
08:51protein coupled receptors and
08:52tie that to function.
08:54And he's also been incredibly
08:57influential and molecular pharmacology
08:59and synthetic neurobiology.
09:02He is really committed to
09:04the open sharing of reagents,
09:06and I think this is one of
09:08the hallmarks of his work.
09:10We've benefited from his reagents as
09:12have probably most most people in the
09:14field that are related to his work,
09:16because there have been more
09:18than 32,000 orders,
09:21probably more by now from Addgene
09:23that have gone to the scientific
09:25community to further to further the
09:28translational work that he is done.
09:31Doctor Roth was elected to the National
09:34Academy of Medicine and to the
09:36American Academy of Arts and Sciences.
09:38He's been named,
09:39which I love.
09:40This one of the world's most influential
09:43scientific minds by Thomson Reuters.
09:45And as you've just heard,
09:47George Aghajanian was a pioneer in
09:49studying serotonin and its receptors,
09:52and now Doctor Roth and his
09:53colleagues have carried out structural
09:55determinations of serotonin receptors.
09:57And,
09:58really excitingly,
09:58his lab has solved the structures
10:01of hallucinogens.
10:02And complex with human serotonin
10:05receptors and the most recent of that
10:09came out in 2020 and cell biology.
10:11In cell biology,
10:13so we don't need more than one word there.
10:17And really, just from a personal note,
10:19Doctor Ruff is very simply a really
10:21fun person to talk to about science.
10:24He is creative,
10:25he doesn't rest in one area and
10:27that I think that restless mind is
10:30what makes an exciting scientist.
10:33So I hope I hope you'll join me
10:35in welcoming Dr Roth for the
10:37Agajanian Lecture today.
10:38He's an ideal person for this lecture.
10:40Thank you for being with us.
10:43Thank you, uh, can you hear me?
10:46Yes yeah OK great.
10:48Uhm, thank you very much.
10:50It's a tremendous honor to.
10:54Give this lecture.
10:57I know George. Ah.
11:01You've seen his picture here.
11:03I just want to say a few things
11:05about George as a person. Uhm?
11:09Let's see here.
11:11Oh so I think everybody who who
11:14has ever interacted with George.
11:16Knows him as a very kind person.
11:19You can see from his face he has this.
11:23Really open uh expression,
11:25warm and generous, and.
11:29He certainly was that was that way with me.
11:34In everything. The other thing is,
11:38his work is tremendously visionary,
11:39so as as mentioned,
11:41he was one of the very first
11:45people to study psychedelic drugs.
11:48Really, from a mechanistic perspective.
11:50Uhm, and that that continued really,
11:55until until recently,
11:57when his lab shut down.
12:00And as well, the the.
12:03A discovery that John Crystal
12:06highlighted for the use of A2 agonists,
12:09Clonidine for the treatment of
12:12morphine withdrawal.
12:12I agree, really, is.
12:14It's a foundational discovery in the area
12:18of neurosciences and biological psychiatry.
12:22And when I give lectures on opioids,
12:26I always present his data because
12:28it is as far I think think.
12:31John is right as far as as anyone knows.
12:34This is this was the first sort of
12:36mechanistic based treatment for a neuro
12:40psychiatric disorder and you know amazingly,
12:44after you know,
12:45I think probably within days or weeks
12:48of making the discovery in the lab they
12:50were already doing studies in patients.
12:52I think across the hall,
12:54so it's it's truly amazing.
12:57And the other thing about George
13:00that that many people don't know.
13:04Uh,
13:04is that I think he's an avid golfer and I,
13:07I never.
13:08I never had a chance to
13:10to play golf with him.
13:12Uh,
13:12but my understanding is from people
13:15who have is that he scrutinized
13:17how you played golf before he would
13:20agree to collaborate with you to see.
13:26To see if to see the sort of person you were,
13:28he could he sort of used that as
13:31a as a psychoanalytic technology.
13:35I told him I didn't play golf,
13:36'cause I wasn't any good at it,
13:37so I I don't know what he what
13:39he gained about my personality
13:42from that but but that's it. Uhm?
13:46So what I want to talk about today
13:49is our our recent studies from my
13:52lab on psychedelic drug action.
13:55And before I start just a few
13:58disclosures as as was mentioned already,
14:01everything from the lab that we
14:04develop is available from aging.
14:07All the work reported here today is
14:10supported by the NIH or by DARPA.
14:13Uhm? Just one note,
14:16I may reveal some compounds toward
14:19the end of the lecture and a
14:21patent has been submitted by Yale
14:23University for these compounds.
14:25So Bill, Yale and you can follow
14:29me on Twitter if you wish.
14:33I don't know.
14:33I'd ask you not to share the data slides.
14:36Because some of this is unpublished work.
14:40So what I'm going to do today
14:42is talk about psychedelics.
14:44And psychedelic drugs of course,
14:46have a long,
14:48long history going back to
14:51the pre Christian era when.
14:54Psychedelic plants like low for a
14:57Willie MC AKA Payodhi tactas thus.
15:03Plant that makes mescalin and the
15:06fungus psylocybe mexicana which makes
15:09psilocybin were widely used, particularly in.
15:15In the Americas.
15:17And.
15:19More recently.
15:22Following the discovery of LSD
15:25by Albert Hofmann in 1943,
15:27there was really a resurgence in interest
15:31in psychedelics as drugs initially,
15:34because it was thought that drugs
15:36like LSD induced a sort of model
15:39psychosis schizophrenia like condition.
15:41Of course,
15:41we don't think that's true anymore,
15:43but it it inspired a lot of research.
15:47And in the 1960s,
15:49a number of mescaline analogs
15:51were synthesized.
15:55By Sheldon and others and his,
15:58uh, his first person accounts
16:01are celebrated now in two books,
16:03pycal and fennel isopropylamine's.
16:06I have known and loved
16:07and Tikal on tryptamines.
16:09I have known and loved.
16:12In in the early 1960s,
16:15biological assays that were or
16:18animal assays that were specific
16:20for psychedelics were discovered,
16:22head Twitch response,
16:23which I'm going to talk about.
16:26A little bit today,
16:29the LSD receptor was discovered by.
16:32Sol Snyder's group.
16:35And then in the 1980s might lab
16:39begins studies on signal transduction.
16:435 HT 2A receptors.
16:45We found that five HT 2A receptors are
16:49localized to pyramidal neurons in the cortex,
16:53particularly in apical dendrites.
16:55And then, more recently we've
16:57been involved in a large number
17:00of structural studies of GPCR's,
17:02highlighted by the first study showing
17:05the structure of LSD bound to a receptor,
17:08and then more recently,
17:10the structure of a psychedelic bound
17:12to a five HT 2A signaling complex.
17:14So I'm going to spend a lot of
17:16time today talking about this.
17:18Uhm, there have been hints in the literature.
17:21This really interesting paper by
17:24Cameron at all published in Nature
17:26earlier this year that we might
17:29be able to develop drugs that have
17:32some of the potential therapeutic
17:34aspects of of psychedelics without
17:36the without the psychedelic activity.
17:39And I'll talk about that at the end.
17:41Uhm?
17:43Before I start, though,
17:44one of the things I would like to distinguish
17:47are psychedelics versus hallucinogens,
17:51so there are a number of drugs that
17:53induce hallucinations or hallucinogenic
17:55life experiences in humans,
17:57including salvinorin, A ibogaine,
18:00LSD, psilocin, and so on.
18:02But psychedelics are defined as LSD like
18:06drugs which activate 5 HT 2A receptors,
18:10and so those will be the
18:12subject of today's talk.
18:14Uhm?
18:14Now folks like George to a great extent,
18:18my lab, perhaps to a lesser extent,
18:21have studied psychedelics.
18:23Psychedelic drug action really,
18:26for many,
18:27many decades,
18:28sort of up in the backwoods of
18:32science because there wasn't
18:34wasn't really a lot of interest
18:36from the general scientific
18:38community about psychedelic drugs,
18:40and certainly not a lot of funding,
18:43and that that has changed recently.
18:46At least interest wise because
18:48of some really intriguing phase.
18:51Two preliminary clinical studies.
18:55And before I summarize these studies,
18:57I just I just want to caution everyone
19:00that these are not definitive clinical
19:02studies and I am not advocating the
19:06use of psychedelic drugs for any
19:08any sort of psychiatric treatment,
19:11but.
19:11But the they have attracted a
19:13lot of interest,
19:14so the first were these
19:16studies by Griffiths at all,
19:18showing that a single dose so psilocybin,
19:21in patients that were depressed
19:23induced a rapid in apparently sustained
19:26antidepressant anxiolytic response.
19:28So you can see here at six
19:31months there still was.
19:34A clinically significant affect and then,
19:39more recently,
19:41Carhartt Harrist and colleagues
19:43published this interesting again.
19:46Phase two trial in the New England
19:48Journal of Medicine, showing that, again,
19:50in this case, two doses of psilocybin.
19:55Induced a.
19:57Apparently sustained antidepressant effect.
20:00Which was statistically not significantly
20:04better than that induced by an SSRI.
20:08Although it does look like it
20:11it if they increase the end,
20:12there might be a statistically
20:14significant effect there.
20:15I just want to note that this is not
20:18a placebo controlled trial now because
20:20of results like this and a large
20:23number of other sort of anecdotal
20:25or smaller studies, there really
20:27has been a tremendous interest in.
20:31In the potential for a psychedelics
20:33like psilocybin for treating neuro
20:36psychiatric disorders and and
20:38hopefully in the next few years
20:40there will be definitive clinical
20:42trials shedding light on this. Uhm?
20:46Now I I basically got into the field
20:49from a pharmacologic perspective.
20:52And over the years.
20:55We've been investigating the pharmacology
20:57of psychedelics in great detail and to
21:00summarize a huge number of studies,
21:03both published and unpublished.
21:05I can say psychedelics have
21:08a very complex pharmacology.
21:10So these are results from a from a
21:13study we published some years ago
21:15where we had developed a platform
21:18whereby we could screen all of the
21:20G protein coupled receptors in the
21:23genome in a single 384 well plate.
21:26And this is a phylogram of of those
21:30Jeep cars and what I've done here
21:34is mapped onto that those receptors
21:36that LSD activates and you can see
21:39it's basically all the receptors.
21:41Down here these are all biogenic
21:43amine receptors. Uhm?
21:46And interestingly enough.
21:49Uh.
21:50Only one of these receptors is actually
21:52thought to be the the site of action of LSD,
21:55at least for its psychedelic effects,
21:57and this is the five HT 2A receptor.
22:01This is in.
22:02This isn't quite distinct contrast
22:04to other hallucinogenic drugs,
22:06so this is this is another
22:08hallucinogen we have studied for many,
22:09many years.
22:10This is drug salvinorin A which
22:12is found in this plant salvia,
22:15which induces a very rapid
22:17hallucinogenic experience in humans.
22:20And what we found using basically
22:23the same platform over the years
22:26was that it is very selective or the
22:29Kappa opiate receptor of all the.
22:31Molecular targets we have screen
22:33now hundreds and hundreds of them.
22:35It only interacts with the Kappa
22:37receptor with high affinity and it
22:38has relatively weak potency for
22:40the for the MU receptor and then no
22:44activity for any other any other target we,
22:47we or others have ever looked at.
22:50We've taken advantage of this
22:52platform that we developed whereby
22:55we can screen essentially the entire.
22:58Family of Druggable G protein coupled
23:01receptors.
23:02To look at a large number of
23:04psychoactive drugs,
23:05including hallucinogens and psychedelics,
23:06and this is now unpublished data
23:09and this shows you the data for
23:12LSD salvinorin A psilocin which is
23:16the active ingredient psilocybin
23:18and nor ibogaine,
23:19which is the active ingredient of Ibogaine,
23:22and you can see that.
23:23Nor Ibogaine really only
23:25activates Kappa receptors.
23:27There's a little bit of activity at
23:29this random orphan receptor salvinorin
23:31has selected for the Kappa receptor.
23:34And then LSD and psilocin.
23:36Of course,
23:37hit many serotonin receptors but also hit.
23:40Dopamine receptors with fairly
23:42potent activity.
23:46Psilocybin, of course, is a prodrug.
23:52This phosphate group, here on psilocybin,
23:56makes it inactive at the
23:58receptor and following ingestion.
24:00It's rapidly D phosphorylated
24:02in the liver to psilocin,
24:04which is the active ingredient
24:06in the active metabolite.
24:08And what we have found is that psilocin
24:11has high affinity agonist potency
24:14at nearly all serotonin receptors.
24:17And this show is sort of
24:19in in summary format. Uhm?
24:22All the all the serotonin
24:24receptors in the genome and you
24:26can see that for many of these,
24:28psilocin has very high affinity,
24:31including all five HT two family receptors,
24:35and then moderate affinity for others and
24:37then a weak affinity for the five HT four.
24:40And it has no affinity for
24:42the five HT 3 receptor.
24:44Uhm, we also found that psilocin is
24:48actually a moderately potent D2 agonist.
24:51And, uh,
24:52and this this has not been reported before.
24:57These data were obtained using a
24:59new platform that we developed.
25:01I don't have time to talk to you about today.
25:05And raises the possibility that
25:07at least some of the actions that
25:09site listen might be mediated
25:11through D2 receptor activation.
25:12Uhm,
25:13because it's it's so prominent in in
25:19research right now we did a a fairly
25:23deep dive in in the pharmacology of psilocin.
25:26We found it's a weak partial agonist,
25:29said five HT 7 receptors.
25:31This is putative target
25:33for anti depressant drugs.
25:36Most worrisome,
25:37it's a it's an agonist at 5 HT 2B receptors,
25:41and many years ago we showed that drugs
25:46that activate 5 HT 2B receptors can
25:49induce valvular heart disease in humans,
25:51and a number of them have been
25:52withdrawn from the market.
25:53So this is this is potentially a downside
25:57for repeated psilocybin administration.
26:00Turns out, most other psychedelics
26:01interact with five HT 2B receptors,
26:04so as a class it's a problem.
26:06For them,
26:06and it's a weak partial agonist for
26:08a number of miscellaneous receptors,
26:10you can see there.
26:12So, given given this really robust
26:16pharmacology of these drugs.
26:19Why is it that we focus on the five
26:22HT two as the target of psychedelics
26:25and the initial information came
26:28from studies in mice by Richard
26:31Glennon where they were able to
26:33show that the head Twitch responses
26:36the psychedelic actions and
26:38mice correlated very well.
26:39The potency for a drug inducing
26:42head Twitch correlated very well
26:44with five HT 2A receptor affinity.
26:46Uhm,
26:47the more definitive studies were
26:49performed by Gonzalez Maeso in 2007
26:52and by my lab in 2009 where we showed
26:56that five HT 2A knockout mice do
26:59not respond to psychedelic drugs.
27:01At least the psychedelic like responses.
27:05But the the most definitive
27:07studies really are those that have
27:09been done in humans.
27:10Franceville Inviters Group was
27:12the first to show this in 1998.
27:15He showed that cancer,
27:17in which is a five HT,
27:192A preferring antagonist,
27:20blocked essentially all the actions
27:23of psilocybin in human volunteers and
27:26then more recently several groups
27:28have shown that virtually all of the
27:31effects of LSD are fully blocked by
27:33cancer and so it does appear that it's
27:36most likely that five HT 2A receptor.
27:40Now, if you were to zoom out.
27:44And look at all known psychedelics.
27:49As well as drugs which have.
27:51Structure similar to psychedelics but are
27:54not psychedelic in humans like listia
27:57ride and bromo LSD and screen them against
28:02a number of important neurotransmitter
28:05receptors which we have done.
28:08Uhm, you would get a heat map like this.
28:11And, uh, given these results,
28:14it would be very difficult or impossible to.
28:17To show that this one receptor here
28:205 HT 2A receptor is responsible
28:24for the psychedelic activity.
28:26But it does,
28:27it does appear that that is indeed the case.
28:30Uhm?
28:34The consequences of this are that these
28:36drugs are potent 5 HT, 2B agonists.
28:39These can cause gobler heart disease.
28:42Many drugs with structural and
28:44pharmacologic similarity to LSD
28:46have been withdrawn from the market.
28:49Interestingly enough,
28:50ecstasy also activates 5 HT 2B.
28:54This is something we showed many years ago.
28:56Chronic ecstasy use can also be
28:58associated with valvular heart disease.
29:00And the big unknown here is it's
29:02unknown which of the many additional
29:05receptors targeted by these drugs
29:07are associated with either side
29:10effects or therapeutic actions.
29:12Uhm, now our current understanding of
29:15psilocybin actions are shown here and
29:19I'm going to go through this diagram.
29:22In a little bit of detail highlighting
29:24results from our labs and others,
29:27and this is from a review which
29:29hopefully will be published soon.
29:32So five HT 2A receptors are found primarily,
29:36although not exclusively,
29:38in layer five cortical pyramidal neurons.
29:41This is a discovery.
29:43My lab made many years ago,
29:45now subsequently course verified
29:48by many others.
29:52And a five HT 2A receptors induce a
29:56very complicated series of downstream
29:59signaling cascades, which which
30:01I'll talk a little bit about today.
30:03I first got my start studying these in 1984
30:07when I was in MIMO, Costas Lab and we.
30:11We basically discovered this pathway
30:13for five HT 2A receptors. Uhm, and then,
30:17uh, you know many years later, uh?
30:21We, along with Peter Penzeys were were
30:24the first to show that psychedelic drugs
30:27can induce a spine formation in neurons
30:30and Alex Kwan's lab recently published
30:32a beautiful paper and neuron showing
30:35that a single dose of psilocybin induces
30:38a sustained increase in spine formation.
30:41Uhm? So, as I mentioned,
30:45five HT 2A receptors are localized to
30:47these April dendrites of pyramidal
30:49neurons in the cerebral cortex.
30:52Uhm, and they coupled to a large
30:55number of downstream signaling events.
30:58Five HT 2A receptors are primarily
31:00coupled to a geographique you where
31:02they promote calcium release.
31:04This can also lead to activation
31:06of protein kinase C as well.
31:09The receptors engage arrest in which
31:12likely is responsible for at least some
31:14of the actions of psychedelic drugs,
31:16which I'll I'll show you shortly.
31:19Uhm, and these are basically
31:22all findings from my lab.
31:25Uhm? Most importantly,
31:28after all of these things happen.
31:32There's increased excitability of
31:34these neurons, and as mentioned,
31:36this was discovered by George Janion.
31:40Uh, and really a Seminole paper.
31:44Was by Gerard Merrick and and George where
31:47they showed that there was an increase.
31:49In a.
31:53It excitability in layer 5 pyramidal
31:57neurons induced by psychedelics.
31:59Uhm? Now we and and this is likely
32:03mediated through this sort of very
32:07complicated signaling cascade.
32:09This is from a review article
32:11that we published in 1987 and you
32:14can see it differs only from the
32:192021 version by being in black
32:21and white rather than color.
32:26So, So what? What George and others
32:30have shown is that when and we've been
32:34able to verify these results in our lab
32:38using reporter mice in which we are able
32:41to do electrophysiological recordings
32:43on five HT 2A identified neurons.
32:48Is that acute administration of
32:51psychedelics to Abbath increase caused
32:54this immediate increase in excitability?
32:58But there's there's a little bit
33:00more to that, and this is this is a
33:02study that I did with a very talented
33:05technician in my lab, Sandy, who fison.
33:08Uh, well we have cortical neurons in there.
33:13Expressing a calcium reporter and
33:15we're going to Bath applied I.
33:19Uh, and you can see immediately
33:21there is this burst of activity,
33:24but if you look closely here.
33:26At the neurons.
33:28You'll see, in addition to the burst,
33:30there's also this sort of spontaneous
33:33increase in spontaneous activity.
33:36And when a large number
33:39of neurons are quantified.
33:41You see something like this,
33:42so this is a pre drug and you can
33:44see that most neurons are quiescent,
33:47although there are some that are active.
33:50When the drug is applied,
33:51there's this gradient,
33:52increasing excitability,
33:53and then there is this sustained.
33:57Increase in what looks like noise.
34:00And what we suspect is that
34:03it's it's actually not this.
34:05Response,
34:06but it's this response this this
34:09noise that's injected into the
34:12system that is responsible for
34:14the psychedelic drug actions
34:16on layer 5 pyramidal neurons.
34:20Now how this occurs is is
34:22still not entirely clear.
34:23We we we have pretty good pretty good
34:27data suggesting that GQ might be involved,
34:30and as I'll show you a little bit later,
34:32arrested might be involved and there
34:36also is now some evidence that various
34:40kinases downstream might be involved.
34:43Uhm, this is this is interesting to us
34:47because we had some years ago found that.
34:54There's interesting kinase
34:56ribosomal S6 kinase.
34:58Can directly interact with five
35:01HT 2A receptors. Yeah, in vivo.
35:04And that it phosphorylates 5 HT 2A
35:09receptors and then more recently in
35:12collaboration with the Krogan and who
35:15to 9 lab a really talented postdoc.
35:18Xiaofeng Zhang has done unbiased
35:22phosphoproteomic studies of cells
35:25expressing 5 HT 2A receptors
35:28where they've been exposed to
35:30the non hallucinogenic 5 HT 2A
35:33agonist lysher rider cellulose in.
35:35And you can see that psilocin
35:38causes increase in phosphorylation
35:39of a huge number of proteins.
35:41I just want to mention here that GSK 3
35:44beta phosphorylation actually is diminished.
35:47Uh, but in particular, many,
35:49many ribosomal S6 kinase is,
35:51and so we think.
35:53We think that this actually
35:54may be one of the keys to the
35:57effects of psychedelic drugs,
35:58and we're investigating that
36:01in great detail the other.
36:04Other sort of studies that we're
36:07doing now to give you a peek at
36:10at at some unpublished data.
36:12Has has been to begin to understand
36:14what the more long term consequences of
36:18psychedelic Drug Administration might
36:20be having on on the transcription,
36:23transcriptome,
36:24and transcriptional machinery.
36:26And for this, we've taken advantage
36:28of a mouse we have created.
36:31Uh, which has a tagged 5 HT 2A receptor.
36:34I'll be showing you this in
36:36a minute and pre recombinase.
36:38This was made by crisper technology.
36:41We cross this with a raibow tag
36:43mouse so that the rybo tag.
36:46This isn't a tagged ribosomal subunit.
36:50Is expressed only in five HT.
36:532A neurons.
36:54This allows us then to do Ribault seek.
36:58Ribault Tag high throughput sequencing.
37:02So basically what we can do is we
37:04can isolate nascent transcripts.
37:06From neurons that only are expressing
37:095 HT 2A receptors before and after
37:13administration of psychedelic
37:15and non psychedelic drugs.
37:17And this is the.
37:19This is a volcano plot shows you
37:21the sort of data we get.
37:23This is a studies done by really
37:26talented student of mine, Jeff Berto.
37:28What we found is actually more than 1000.
37:31Transcripts are relatively
37:34rapidly regulated by this five HT,
37:382A preferring psychedelic drug,
37:4025 cyano envo.
37:41And by contrast,
37:43the drug glycerides which is non psychedelic.
37:47Caused only about a dozen
37:49transcripts to be changed,
37:50so we think this this may be a
37:53signature for psychedelic drug action.
37:55When we did a dive into the,
37:57uh, uh, what types of UM?
38:02Transcripts were altered.
38:04You can see that it's many of
38:08them involved in neurogenesis.
38:11Spine formation and so on are are among
38:15the leading candidates and and so this is.
38:22This is pretty interesting,
38:24and as we go further I think will give us.
38:28More clues into what?
38:30What might the basis for some of these
38:34long lasting effects of psychedelic
38:36drugs be beyond just changing
38:38the number of spines on a neuron.
38:41Uhm, I want to spend the rest
38:43of the time though.
38:45Focusing on really what has been
38:48a long journey for me in my lab.
38:51Which is to understand how drugs like LSD.
38:55Bind to and activate these receptors,
38:58since it appears that these are the
39:00receptors responsible for their actions.
39:02And to give you a sense of
39:05how long this journey is,
39:07this is one of my first papers published.
39:12Add and summarized his work that
39:14was begun when I first started my
39:16faculty position at case Western.
39:18Uh, in 1991. This is the first.
39:24Color cover of the journal
39:27Molecular Pharmacology.
39:28And what we did was we did
39:32molecular modeling and site
39:34directed mutagenesis studies.
39:36Of course we didn't have any receptor
39:38structures in those days to try
39:40to understand how drugs like LSD.
39:42You can see here as well as
39:45this non psychedelic drug.
39:47I hide your origami how they might
39:50interact with five HT 2A receptors
39:51and what what we proposed actually was
39:55that there were key residues here for.
39:59For specifying LSD action and
40:01that the non psychedelic drugs
40:03actually would bind differently to
40:05the receptor then psychedelics.
40:09If we go forward. Uhm?
40:14In a in a series of papers first published
40:18by Daniel Wacker from my lab in 2017
40:21and then more recently by Koo Kim,
40:25we were able to understand the
40:28actions of psychedelic drugs at the.
40:31Near atomic level by X ray crystallography
40:34and cryo electron microscopy.
40:37And before I show you the data I
40:39want to show you this little movie
40:41here which was produced by Gabriel
40:43Ashlynn of Ribose Film Studios and
40:46this was presented on the very last
40:49episode of Hamilton's Pharmacopia.
40:51And this is LSD and.
40:56Uh, for those of you who?
40:59Uh, we'll find the rest of what I present.
41:02Somewhat mystifying or too much for the
41:08specialists II urge you just to watch this,
41:10because all of the key points are are in
41:12this little movie here, so here's lsted.
41:15Uhm? It's flying through space.
41:19Imagine someone has just taken LSD.
41:21It's. Flying through their body.
41:25And soon it's going to come in close
41:29communication with the receptor here.
41:31And here you can see the five
41:33HT 2A receptor there in white.
41:35You can see the large extracellular
41:37amino terminus there,
41:39floating and LSD sort of bounces around
41:41for a little while before it finds this
41:45very tight location in the receptor.
41:48Then it stabilizes a conformational change
41:50of the receptor and this is communicated.
41:55From the outside of the cell.
41:58To the inside of the cell.
42:01Where the receptor here in white?
42:03Communicates with heterotrimeric G proteins
42:05and you'll see this is the G alpha subunit.
42:08This is the beta gamma subunit.
42:10They're now going to fly off and
42:13activate various downstream effectors.
42:15So the goal of my lab really
42:18for 30 years has been.
42:20To understand this process.
42:23And.
42:23We sort of understand it now.
42:26And the work,
42:28the real data that I'm going to
42:30show was developed by an extremely
42:32talented team of postdocs in my lab.
42:35Most all of whom now have their own labs.
42:37Shang, Tao,
42:38Daniel and John all have
42:40their own faculty positions.
42:42Brian Crum, still in the lab.
42:44If you're looking to hire someone,
42:47he'll be on the job market soon.
42:49Uhm,
42:50and so the first.
42:53The first finding was we were able to
42:55obtain the structure of LSD and complex
42:58with the human serotonin receptor.
43:00This was the five HT 2B receptor.
43:02It wasn't the two a 'cause we couldn't
43:04couldn't crystallize it with a two way.
43:08But it was important enough
43:10that it made the cover of sell,
43:13and to my delight,
43:15many of the predictions that
43:18we had made many,
43:20many years ago were verified once
43:22we had the crystal structure.
43:27And in particular,
43:30there were these two aromatic residues.
43:33These phenylalanine that we had predicted
43:37would stabilize the indole moiety of LSD
43:43and would be key to receptor recognition.
43:47And I was particularly happy to see this.
43:51Because, uh. In the early 1990s we
43:55had presented the data suggesting
43:57that these residues were involved.
44:00In psychedelic drug binding to the receptor,
44:03I remember presenting it
44:05at a neuroscience meeting.
44:06One of these short talks.
44:09There are a couple of 100 people in the
44:11audience and at the end of the talk.
44:13Uh, somebody who I won't mention who it is.
44:17Nobody from Yale stood up and said
44:20this cannot possibly be true.
44:22And a few weeks later my grant was
44:25reviewed and was was was nerfed.
44:29Nonetheless, we persisted,
44:30and it turned out we were correct.
44:34Uhm, the other.
44:36The other thing that we found
44:38with this receptor with this
44:41structure published in 2017,
44:43as well as finally we got the structure of
44:46LSD with the five HT 2A receptor in 2020.
44:50Was that there was a lid
44:52that was formed over LSD.
44:54By this loosening residue.
44:57And this lid basically falls.
45:02Fits over the top of LSD so that LSD
45:05can't get out of their receptor.
45:07And and because of this,
45:08LSD is a very long residence
45:10time in the receptor.
45:11Basically once LSD is on the receptor,
45:13it's there for two to three hours at least,
45:17and this explains in large part
45:20why LSD actions are so prolonged.
45:23Jor Rhonda Ross Lab did molecular
45:27dynamics simulations of this,
45:30and this is an MD simulation of
45:34LSD with the native receptor here,
45:37and you can see this leucine here
45:39and you can see LSD is pretty
45:41stable here in the binding pocket.
45:43When the leucine was changed to an alanine,
45:45we can see that LSD is now moving around.
45:48A bit more begins to actually float
45:50out of the binding pocket and we are
45:54able to show by biophysical studies that.
46:00Mutants, uh?
46:01Of this of this residue,
46:04greatly accelerate the off time
46:06of LSD from the receptor,
46:08so we think this is key for LSD's actions.
46:12Uhm? The other big advance was.
46:17Obtaining by cryo electron microscopy.
46:20The structure of the five HT 2A
46:23receptor bound to a psychedelic drug
46:26and bound to the heterotrimeric G
46:28protein GI thank you and this is a
46:32study that was done principally by
46:34KU from my lab and Julianna Pena
46:37over from your Goscinny Ellis lab.
46:41To cry OEM Soku basically did
46:43all the biochemical studies,
46:44purify the receptor, send it to them.
46:46They solved the structure.
46:48And I'm just going to show
46:50you some details here.
46:51Here you can see this psychedelic drug 25
46:54sayano in Bo bound to the receptor here.
47:00This is a space filling representation.
47:03Uh, we're going to zoom up on
47:05the the G protein interface.
47:07The alpha subunit there is in blue.
47:10Uhm, there's the receptor.
47:11You can see that with this drug.
47:14The binding pocket is relatively open.
47:17Uh, there is the drug is in yellow.
47:22And, uh.
47:24And it has a sort of really interesting
47:27mode of interaction with the receptor,
47:30which I I'm not going to go in today,
47:32so this this was really a breakthrough.
47:35This is actually discovering.
47:40Psychedelic drug action
47:42at the molecular level.
47:44And along with this active state structure,
47:47we were able to obtain inactive state
47:50structures of the five HT 2A receptor,
47:53and this allowed us to map the
47:55transitions that occur between
47:57the active in the inactive state.
47:59And they're shown here,
48:00and I'm not going to go
48:02into any of these in detail.
48:03There only probably one or two structural
48:07biologists here in the audience.
48:09But just to let you know that it gives
48:11us great insight into into basically
48:13how drugs activate the receptor.
48:18I'm now going to show some some new data.
48:21Uh, and this is some amazing
48:24data that has has recently been
48:27prepared by an extraordinarily
48:29talented postdoc at mine, Ryan,
48:31in collaboration with Jonathan Fay,
48:33who's the local cry OEM
48:36wizard here at at UNC and.
48:42Collectively, over the last year or so,
48:46they've been able to obtain a large
48:48number of structures of the five HT 2A
48:52receptor and another serotonin receptors
48:54related serotonin receptors with
48:57psychedelic and on psychedelic drugs.
48:59So I'm not going to go into any
49:00of these structures in detail,
49:01but just to let you know,
49:02we now have the structure of mescalin.
49:04We have the structure of
49:05NN Dimethyltryptamine.
49:06We have the structure of psilocin.
49:09So basically all major psychedelics
49:11we have structures of.
49:12We also have structures of the
49:15non psychedelic compounds blsa
49:17ride as well as serotonin,
49:19and we're using these structures for
49:21structure guided drug discovery,
49:23which I'll I'll go over here
49:27in just a minute.
49:28Uhm, now one of the other things that we
49:32noticed about about LSD in particular.
49:35Uh, and if you remember I I said early
49:37on that five HT 2A receptors not only
49:40activate this geovic you signaling pathway,
49:43they also activated arrestin signaling.
49:46What we found was that if we did
49:49dose response studies looking at
49:51the ability of LSD to activate
49:54arrestin versus gioffre Q,
49:56we found that it was much much more
49:58potent for activating arrested the GL.
50:01Thank you.
50:03And this led led to the idea that LSD,
50:07maybe an arrest in biased ligand for
50:12the serotonin receptor and that that
50:15this might be responsible, at least in part.
50:19For some of the actions of LSD.
50:22And so to begin to.
50:25But test this hypothesis.
50:27This is,
50:29this was recently published.
50:30This was a study that was done by Ramona
50:34Rodriguez in Bill Wetzel's Lab at Duke.
50:37They evaluated the ability of LSD to
50:39induce head Twitch response in wild
50:42type mice versus beta arrestin 2
50:45knockout mice and to make a Long story short,
50:48what they found was that of course LSD
50:51induces head Twitch response very robustly.
50:54This response can be blocked by a
50:56five HT 2 antagonist and 109 oh,
50:59seven and that this response is
51:02greatly attenuated in beta arrestin 2
51:05but not beta arrestin one knockout mice.
51:08Uhm,
51:08and as well a number of other sort
51:12of classic effects of psychedelic
51:15drugs on mouse phenotypes were also
51:20attenuated in the bait arrested.
51:21Two knockout mice.
51:22One of the ones that I like to highlight
51:24is this disruption of prepulse inhibition.
51:27You can see that LSD greatly
51:29disrupts prepulse inhibition here,
51:31but there is no effect.
51:35In debate,
51:36arrested two knockout mice and because
51:39LSD disrupts prepulse inhibition in both.
51:43Mice and humans?
51:45Uh,
51:45this is potentially a translational
51:48biomarker going forward for investigating
51:52the psychoactive effects of LSD,
51:55as distinct from potentially novel
51:58drugs that may not be psychoactive.
52:01Uhm, as I mentioned,
52:03we have a we have been creating
52:05a number of mice.
52:06UM, we.
52:08To study this in in more detail
52:12and I just want to mention,
52:14uh,
52:15there are five HT 2A cream ists
52:18that are available through gensac.
52:21I would urge you not to use those
52:24mice because the cells that are
52:26labeled by creari combinations are
52:29not five HT 2A expressing
52:31mice 5 HT 2A receptors.
52:33We found this out some years ago and because
52:37of that went to the trouble to create.
52:40Uh, our own set of mice using
52:43CRISPR technology.
52:44And I'll just show you results from 1.
52:48One of the various types of mice we've made,
52:51this is a mouse in which the five HT
52:532A receptor has been tagged with GFP
52:56in such a way that it does not affect
53:00receptor expression or function.
53:02And then downstream of that 'cause pirates
53:04and then a estrogen responsive Cree.
53:08And you can see here from
53:10this sagittal section here,
53:11that the distribution of five HT 2A
53:14receptor protein is virtually identical
53:16to that which was identified by receptor
53:20autoradiography with M109O7 many,
53:22many years ago by the Palacios lab.
53:26I also want to point out this patchy
53:29distribution here in the striatum
53:31which which is sort of hinted
53:34at here in this autoradiogram.
53:36But the resolution is just
53:38not sufficient to see it.
53:39So we think there are some.
53:41There's some interesting activity
53:42here in this trisome,
53:43but the key thing here is these layer 5
53:46neurons are just really really lit up.
53:48And and so we we crossed these five
53:51HT 2A estrogen responsive Cree with
53:55Phlox beta arrestin 2 knockout mice.
53:59Treated them with tamoxifen.
54:01And then evaluated the ability of LSD
54:04and DOB to induce hedgewitch response.
54:07And you can see in both cases
54:09the effect was attenuated.
54:10It's not.
54:11It's not abolished,
54:12but it's attenuated again,
54:14suggesting that there might be
54:16some role for beta arrestin in
54:19addition to GQ signaling,
54:20for for mediating the effects of
54:24psychedelics at the molecular basis.
54:26OK,
54:26I want to finish now with with
54:28some very recent studies which are
54:31currently in review which were done
54:33in collaboration with the Ellen Lab
54:35here at Yale University by a very
54:38talented student of his Denise Confair.
54:40In collaboration with my lab,
54:42the Irwin Lab at UCSF,
54:43and the Shortcut Lab at at at UCSF.
54:48And,
54:49uh,
54:49what was done here was now that we had
54:53the structure of the five HT 2A receptor.
54:57We wondered if we could use it for
55:00structure based drug discovery.
55:02And in the past the Choquette Irwin
55:06lab in my lab have published a number
55:09of studies where we've done what
55:11we call ultra large scale docking,
55:13where large numbers of commercially
55:16available compounds are docked
55:18to a receptor structure,
55:20and then they eventually become seed
55:23compounds for medicinal chemistry efforts.
55:26Now,
55:27one of the problems with using these
55:29commercially available libraries is
55:31they're they're relatively congested.
55:33In terms of chemical space.
55:36And one of the one of the areas
55:38of chemical space which are
55:41relatively underrepresented,
55:42underrepresented in these large
55:44libraries are tetrahydro purities.
55:46And so Jonathan Elman really is a wizard at
55:50at sort of diversity oriented synthesis.
55:54And so he and Denise had.
55:56Uhm,
55:57envisioned a way in which a
55:59large virtual tetrahydro purity
56:01library could be made.
56:03So this is a library that exists in theory,
56:06whereby relatively simple
56:09building blocks can be.
56:11Combine to make large,
56:13potentially large chemical libraries.
56:16In this case. This is a library of.
56:1975 million virtual tetrahydro purities.
56:22And what was done then is this
56:26was then docked to the receptor,
56:28and then an iterative cycle of
56:30docking and synthetic collaboration
56:32and optimization was performed.
56:34And ultimately,
56:35this compound 3366 was revealed as
56:39a relatively potent and selective,
56:41and importantly, GQ biased 5HT2 agonist.
56:45And the approach that was used has
56:48been described previously and I just
56:49want to point out these two papers
56:51that will be coming out in nature
56:53here in the next month where this
56:55was done on other other targets.
56:58Uhm, and so the way the docking
56:59is done is this.
57:00So each ligand separately is
57:03docked in multiple confirmations
57:05and you can see that there,
57:07and for each confirmation
57:10score is calculated.
57:12So you can see them docked
57:14and the score is calculated.
57:16And then,
57:17uhm.
57:20The Top Rank scores chosen for each
57:22of the hundreds of millions of
57:24compounds that are docked and then
57:27all the compounds are ranked and
57:29then a subset of them were tested.
57:34Uh, and ultimately optimized to
57:36this very potent compound 3366.
57:39So we had this compound 3366 we had
57:43predicted based on our computational studies,
57:47how it might bind to the receptor.
57:49We found that it bound to the receptor.
57:51We wanted to determine if our predictions
57:53were correct and so we enlisted the
57:57assistance of our collaborator,
57:59Jargo Skinny Otis at Stanford,
58:02and this really talented postdoc
58:04Cometa Barrows.
58:05Alvarez, who's now in the biotech industry.
58:10And they perform cry OEM elucidation
58:13of the structure of this this new
58:17compound with the five HT 2A receptor
58:20and what you can see here in green is
58:23the predicted pose of the compound
58:26in the receptor and in purple.
58:28Here is actually the solved pose by
58:31cryo electron microscopy and you can
58:34see that it was pretty close actually.
58:37So the cryo EM structure superposes quite.
58:40Well, with a computational prediction.
58:43Uhm,
58:44we tested the compounds for 4G protein bias,
58:49which you can see here.
58:50They're they're fairly biased.
58:51I'm not going to go into that in any detail.
58:54We also tested the drug like properties
58:56of these compounds and.
59:00What we found was that after IP
59:04administration they were had
59:06tremendous bio availability and were
59:10actually concentrated in the brain.
59:12You can see here for this compound here
59:14the brain to plasma ratio was about 8 to one,
59:17so these are extraordinarily
59:19good for drug like properties.
59:22So,
59:22uh.
59:23We decided to because there has
59:25been this flurry of interest that
59:28psychedelic drugs might have
59:30antidepressant drug like activity.
59:35We decided to test them in a model
59:39of antidepressive drug like activity
59:41and this this model is based on the
59:44use of beam at two heterozygote mice.
59:47So beam at two is specifically
59:49or monoamine transporter.
59:51It's the site of action of reserving
59:53psychiatrist in the audience.
59:55Will will remember that reserving was shown
59:58in the 1950s to deplete biogenic amines,
01:00:02which used as a as a treatment.
01:00:05For hypertension and as a side effect caused
01:00:09depression and nightmares in individuals.
01:00:12And so mice that that are heterozygote for
01:00:16beam at two have quote unquote depressive
01:00:19like phenotype and so so we tested
01:00:24these mice in the tail suspension test.
01:00:27You can see that the beam at hit mice
01:00:30have have show a longer suspension
01:00:33time in the tail suspension test
01:00:35compared to the wild type mice.
01:00:3820 milligrams per kilogram of luak
01:00:40sytin basically restores this too.
01:00:42Baseline and then .5 megs per kilogram
01:00:47and 1 milligram per kilogram of.
01:00:51Of of this compound in a related
01:00:53compound have a similar antidepressant
01:00:55drug like action as 20 milligrams
01:00:58per kilogram fluoxetine.
01:01:00This doesn't mean that these
01:01:02are antidepressant drugs,
01:01:03but this just that they have antidepressant
01:01:05drug like action in this test.
01:01:08Are they psychedelic now?
01:01:10Remember I said that we had this this
01:01:13intriguing evidence that arrestin
01:01:15signaling may have something to do with
01:01:18the psychedelic action of these compounds.
01:01:20And that these drugs tend tend not
01:01:23to activate the arrestin pathway,
01:01:26and so we tested them in the
01:01:28head Twitch response at.
01:01:30At doses that are similar to those that
01:01:33have an antidepressant drug like response,
01:01:35you can see absolutely no effect
01:01:37in the head Twitch response.
01:01:40And no effect in a locomotor response either,
01:01:44and and finally no effect in many many many
01:01:48other tests of psychedelic drug action.
01:01:52So what we have basically are compounds that
01:01:55apparently interact with five HT 2A receptor.
01:01:58They activate it,
01:01:59they have an antidepressant drug like action,
01:02:01but there don't have psychedelic
01:02:03drug like effects and so Yale has
01:02:06filed a patent on this compounds.
01:02:08Uhm,
01:02:08so that gives you an idea of of what
01:02:10we're doing and where we're going.
01:02:12Obviously we're very excited
01:02:14about these results and.
01:02:18Were were attempting to
01:02:20create even better compounds,
01:02:23both the psychedelic and non psychedelic
01:02:26that interact with the five HT 2A receptor.
01:02:28Ultimately to be used as chemical
01:02:30tools to begin to test some of the
01:02:33hypothesis of psychedelic drug action.
01:02:35It would be really important to have a
01:02:39drug which activates 5 HT 2A receptors.
01:02:43And no other receptors.
01:02:46If nothing else to test the hypothesis
01:02:49that the psychedelic effects really
01:02:51are due to five HT 2 receptors,
01:02:54and so on.
01:02:55And so that's that's what we're doing.
01:02:57As well as solving structures,
01:02:59I just want to thank the various folks in the
01:03:01in the team that that were involved in this.
01:03:03In this work,
01:03:04I think I've highlighted them all.
01:03:06I want to give a shout out to Bill Wetzel
01:03:08and Ramona Rodriguez.
01:03:10Denise Confair, who's now at.
01:03:14I forget which pharmaceutical company.
01:03:18Maybe AstraZeneca now from the element lab.
01:03:22Ruth Hooten Hines, Lab, Chow fan,
01:03:24Zhang Gorgo Skinny Otis lab,
01:03:27Brian Shoichet slab,
01:03:28and Dave Nichols and all the work
01:03:32is supported by your tax dollars.
01:03:34This longstanding and IMHO psychoactive
01:03:37drug screening program provides
01:03:39all the pharmacologic profiling and
01:03:42is available to anyone else who.
01:03:45Who who has interesting compounds
01:03:47they liked us to look at in
01:03:49the last three years or so,
01:03:51we've worked with more than 400
01:03:52different labs around the world,
01:03:54as well as DARPA.
01:03:55That that's funding this work,
01:03:57and I'm happy now to answer any
01:03:59questions that you may have.
01:04:01Thank you.
01:04:05Thank you so much. That was a comprehensive
01:04:08walkthrough. A lot of really
01:04:12impressive science, so I I am going
01:04:15to ask everybody who would like to
01:04:17ask a question live just to raise
01:04:19your hand using the reactions.
01:04:23Tab, because that allows me to see you
01:04:26when you ask the question and or if you'd
01:04:29rather not ask your question out loud,
01:04:31please put it in the chat.
01:04:32If there are any trainees on the line
01:04:34who would be willing to ask a question,
01:04:37that would be an ideal way to start off.
01:04:39So I'll give you one second to raise
01:04:42your hand, and if not we'll go to
01:04:45some of our more senior colleagues.
01:04:51OK, well in that case we'll start with
01:04:54Doctor Cederbaum and will let our trainees
01:04:56get their get their questions together.
01:05:01If you could unmute, yeah, thank
01:05:03you very much for really,
01:05:04really, really fascinating talk,
01:05:06so will disclosure here.
01:05:09I'm a neurologist and
01:05:11done a lot of work in the area of
01:05:13Parkinson's disease and one drug that's
01:05:15proved to be helpful in somewhat in
01:05:18managing delusions and hallucinations
01:05:21in Parkinson's disease is pimavanserin,
01:05:23which is a relatively selective 5 HT,
01:05:2925 HT 2A. Inverse agonist,
01:05:32as it's been characterized,
01:05:33and I'm wondering if you've had a chance
01:05:35to look at this and similar compounds,
01:05:38particularly with respect
01:05:40to how they might be
01:05:42biasing a receptor activity, thinking whether
01:05:48there is some opportunity here
01:05:50to investigate mechanisms for perhaps
01:05:53using these compounds in a preventative
01:05:56mode rather than simply a symptomatic
01:06:00treatment mode.
01:06:01Yeah, we have and we published this.
01:06:05So, uh, I'll just briefly summarize
01:06:08what we found. So one of the.
01:06:11One of the really interesting things
01:06:13about five HT 2A receptors and what.
01:06:15Basically what got me interested
01:06:17in them in the beginning.
01:06:19Uh, in the 80s? Was that, uh,
01:06:22unlike virtually all other receptors,
01:06:25antagonists cause a downregulation
01:06:28of five HT 2A receptors.
01:06:32And and it turns out it's not all
01:06:36antagonists, so some antagonists,
01:06:38downregulate 5 HT 2A
01:06:40receptors when given acutely.
01:06:42So you can give a mouse.
01:06:44A 10 milligrams per kilogram of
01:06:47clozapine and then two days later,
01:06:50five HT 2A receptors are
01:06:52downregulated 50 or 60% OK.
01:06:55Uhm, and so we wondered basically two things.
01:07:02Is this really a decrease in receptor
01:07:04number or is the is the ligand just
01:07:07trapped on the receptor that was the
01:07:09first question we wanted to answer?
01:07:11And the second one was.
01:07:13If we look at drugs that are
01:07:15therapeutic versus non therapeutic.
01:07:17Is there any segregation into
01:07:19those that cause down regulation
01:07:22versus those that don't right and
01:07:24so once so it turned out it took a
01:07:27long time to answer that question.
01:07:29And the answers were yes,
01:07:31they cause a decrease in receptor protein.
01:07:33So we definitively showed that.
01:07:35And secondly,
01:07:37there is no difference between drugs
01:07:40that are therapeutic and drugs that
01:07:41are not therapeutic in terms of whether
01:07:44they cause down regulation or not.
01:07:46So we actually looked at him
01:07:47of answer in that paper and it
01:07:51does not cause downregulation.
01:07:53Whereas clozapine ducks.
01:07:56Uhm, so uh,
01:07:58that's not to say that there isn't anything
01:08:01interesting going on, but just that.
01:08:03We're not able to see what it is yet.
01:08:06I think there might actually be
01:08:08something really interesting going on.
01:08:09We don't know what it is so.
01:08:13Great question.
01:08:14Thanks.
01:08:19I had a small question.
01:08:20It's it's some sort of about
01:08:23that subtle difference between
01:08:25the predicted docking site and
01:08:27then the cry OEM docking site,
01:08:29and I wondered if if it gave you some
01:08:31insight into what aspects of the in
01:08:33silico model needed to be tweaked,
01:08:35or whether it had any implications
01:08:37for what might change upon binding.
01:08:42We were just happy about similar
01:08:44close. Yeah, it was pretty close. It
01:08:47was close enough, yeah? Got
01:08:50it, I knew it was a small question.
01:08:52No, it's it's a great question.
01:08:55And it it turns out it.
01:08:59You know, it's technically.
01:09:03To do the experiment was like really,
01:09:04really difficult. It's technically
01:09:06a very difficult experiment to do,
01:09:08and so we were happy with that.
01:09:10We could even see the link, and yeah.
01:09:14In in another paper that
01:09:16was published in 2019.
01:09:19In in nature, sort of,
01:09:21the first ultra large scale docking study.
01:09:26The shark at lab looked at a.
01:09:29At compounds that were were binding
01:09:32to beta lactamase so beta lactamase
01:09:34they could easily get X ray structures
01:09:37of compounds that were predicted
01:09:38to bind and were found to bind.
01:09:41And the predicted binding poses
01:09:44were actually quite good.
01:09:47And let me just say that.
01:09:52I'm not going to show it today, but.
01:09:54You know? I will show we have a
01:09:57paper in another paper in nature.
01:09:59That's that's impressed.
01:10:01Where there's another another receptor.
01:10:06Mr MRGPRX receptors,
01:10:08where we had previously predicted
01:10:11how a compound would bind.
01:10:14And when we solve this structure,
01:10:16it was completely wrong.
01:10:20It wasn't even close.
01:10:23So that's a good negative control.
01:10:26Yeah, doesn't always dock.
01:10:29Network no, that's funny.
01:10:33We have a question from Clara,
01:10:35Clara, Leo Clara. Hi, uh,
01:10:38first of all, thank you for that.
01:10:40Talk was really awesome to hear all of that.
01:10:43My question is in relation to
01:10:46the recent casarotto sell paper
01:10:48about Turk be binding and was
01:10:50wondering if you detected any Turk
01:10:53be activation or in your screening
01:10:56of binding of psychedelics.
01:10:59Says again.
01:11:00Uh, this is the casaretto cell
01:11:02paper that just talked about how
01:11:04antidepressant drug action binds to Turk.
01:11:06Be no
01:11:07track B yeah. Track fee yes yes.
01:11:13So, uh, I'm skeptical about that paper.
01:11:17Let me just say that that's all I'll say. Did
01:11:22you see any, UM, results from your screening?
01:11:25So we come. We don't see any signal
01:11:28from track fee in the proteomics.
01:11:31The phosphoproteomics we don't
01:11:33see a track B signature at all.
01:11:35And we don't see anything
01:11:38by the transcriptomics.
01:11:40That doesn't mean it's not involved,
01:11:42and I'm sure it's involved in Academy
01:11:44for instance, and other anti depressants.
01:11:46It might be that there is a.
01:11:49You know that psychedelic drugs?
01:11:52Basically have the same common endpoint,
01:11:55which in part is synaptogenesis, but they
01:11:59do it by slightly different mechanism.
01:12:01And if you go back to the paper
01:12:03that we published in 2009 uh,
01:12:06with Peter Pensus lab. Uhm?
01:12:11We we invoke basically PDZ domain
01:12:15proteins in in mediating the.
01:12:17The rapid spine formation. Uhm?
01:12:22Yeah so. But yeah, good question.
01:12:26Yeah.
01:12:27Thank you, Clara.
01:12:28Ideal do you have a question?
01:12:31Yes hi hi this is Adele Traversion time.
01:12:36From the Yale community.
01:12:37Now in clinical trials,
01:12:40UM and we do run several clinical trials,
01:12:44one in action, including psychedelics
01:12:48psilocybe in compound as,
01:12:51and so in depression.
01:12:54So, uh, this is incredibly interesting to me,
01:12:57but I have to say that I feel a
01:13:00little bit disappointed to hear
01:13:02that it's just five HT 2A receptor,
01:13:05or to try to put it together
01:13:09with what we are.
01:13:11Are experiencing or are hoping
01:13:13to see in clinic where, UM.
01:13:16Just one dose of this drug is supposedly,
01:13:23uh, going to improve or can be life changing.
01:13:29In some anecdotal things.
01:13:31For for people with depression
01:13:35or addiction etc.
01:13:37So I'm trying to put together in my mind.
01:13:39Of course we have the Academy
01:13:41in experiments as well,
01:13:42but how is it that the effect on
01:13:475H22A account for their quite profound
01:13:52experience the patients have and we
01:13:55don't have yet the results of our trials,
01:13:59but you know,
01:14:01the initial idea that perhaps
01:14:03those are very long lasting
01:14:05changes and improvements.
01:14:10Could you speak to this little bit?
01:14:13Yeah, so first let me say that we
01:14:15don't know if it's the five HT 2A
01:14:18receptor that's responsible for the
01:14:19therapeutic action of these drugs
01:14:21because the experiments have not been
01:14:24done with five HT 2 antagonists.
01:14:28I suspect they are, but we don't know.
01:14:32The in terms of the psychedelic effects.
01:14:37Uhm, so I think we understand.
01:14:39At least I understand that maybe I can
01:14:41explain it in a way that's understandable.
01:14:44So these layer 5 pyramidal neurons
01:14:47actually serve as integrators for
01:14:49sensory and cognitive information
01:14:52throughout the entire cortex.
01:14:54So everything feeds into these into these
01:14:56layer 5 brandable neuron apical dendrites.
01:14:59They serve as basically the
01:15:03integrators for how we view reality.
01:15:06And as I as I showed you,
01:15:08what happens when LSD or some other
01:15:11drug activates these receptors is
01:15:14initially the neurons fire rapidly?
01:15:17Uh, But that's that's rather transient
01:15:19and what's sustaining to actually,
01:15:22is this increase in noise?
01:15:24So basically what we think is going on
01:15:26as you're injecting noise in the system,
01:15:29so you're basically injecting
01:15:31noise into the very neurons that
01:15:33tell you how to view reality,
01:15:36and this is then interpreted.
01:15:37Basically,
01:15:37a story is then made up by the brain for
01:15:41this or this sort of change in input.
01:15:45And we think that's the psychedelic
01:15:47experience, and it's my suspicion that.
01:15:51Uhm, and the other thing.
01:15:53The other thing that that happens
01:15:55that's I think relatively unique for
01:15:57psychedelics that we don't understand.
01:15:59Is that UM? The experience has a
01:16:03tremendous amount of salience.
01:16:06So if you talk to people that have
01:16:08taken a psychedelic drug.
01:16:10They remember it.
01:16:11It's it's a profound experience for them.
01:16:15This is not the case
01:16:17when people take ketamin.
01:16:19When they drink alcohol,
01:16:21unless they're alcoholic.
01:16:22Uh and so on.
01:16:24So there's something about, uh?
01:16:29Changing you know altering the neuronal
01:16:32properties of these neurons that.
01:16:35Uhm, in gender salience.
01:16:37Uh and and I don't know what that is,
01:16:40I I wish I did,
01:16:42but clearly is a five HT 2A
01:16:44receptor because if you block it,
01:16:45the drugs don't have it.
01:16:46They don't have a psychedelic effect.
01:16:48Now the the thing that we're trying
01:16:53to understand is.
01:16:54These drugs, you know,
01:16:56if you believe the pre click the studies.
01:16:58Basically a single dose
01:17:00is resetting the brain.
01:17:02And how is this happening?
01:17:04We don't know how it's happening and
01:17:05that's what we're trying to find out.
01:17:07So we have a huge grant from DARPA.
01:17:14To to to basically do A to do a
01:17:18Manhattan Project level study
01:17:21of the basic biochemistry,
01:17:24transcriptional machinery and
01:17:25signaling downstream of five HT
01:17:282A receptors in these neurons and,
01:17:31and we're hoping that will.
01:17:34We'll find something out that will
01:17:36begin to elucidate how these drugs work,
01:17:39but I I share your frustration as well.
01:17:42Sadly, there isn't a lot of
01:17:46funded research on psychedelics,
01:17:47so I think right now I have the only
01:17:50NIH funded grant to study the basic
01:17:54science of psychedelic drug action.
01:17:56So until until we have more
01:17:58investigators in the field work,
01:17:59we're going to,
01:18:00we're going to have a lot of
01:18:01these unknowns and and I share
01:18:04your frustrations as well.
01:18:06Write, write to your congressman
01:18:10and the Institute of Directors.
01:18:14I see Gerard Merrick yeah Gerard
01:18:17before we high Gerard go ahead hello get to
01:18:20a couple of questions from the chat. Great
01:18:24talk as usual Brian.
01:18:25I always enjoy your talks but one of
01:18:27the questions I was curious about.
01:18:29You know obviously speaking about
01:18:31the salience of what hallucinogens
01:18:33are doing and like the ideal
01:18:35one dose effects when you start
01:18:37moving though to the compounds that
01:18:39are not affecting the head
01:18:41Twitch response for example.
01:18:43What are you sort of imagining?
01:18:45'cause I was sort of
01:18:45thinking to what degree
01:18:46do you think that
01:18:48there may be some similarities
01:18:50between just simply blockade
01:18:52of two a receptors versus the
01:18:55downregulation of two a receptors
01:18:57that are occurring with lucid gems?
01:19:00And to what extent are those?
01:19:01I guess it's empirical question
01:19:03to what extent different pathways
01:19:05going to be down right? But
01:19:06what are your initial thoughts
01:19:08right now? I don't know.
01:19:13I I wish I had something. Smart to say.
01:19:19I love that answer. That's the
01:19:20best answer I've ever tried to
01:19:22find out what the hell is going on.
01:19:24It's pretty mysterious to me too,
01:19:26so I'll keep following you.
01:19:29Certainly yeah, yeah,
01:19:31let me ask a couple of questions from
01:19:33the from the chat so Christian Maury
01:19:35asks do you think that the longevity
01:19:38of LSD action in the receptor also
01:19:40contributes to the rapidity of development
01:19:42of tolerance reported by users of LSD?
01:19:45Yeah yeah. So what I think it does.
01:19:48So what? One of the things that LSD
01:19:51does is it also down regulates 5 HT
01:19:532A receptors with a single dose,
01:19:55and it's likely that that long
01:19:58residence time in the receptor
01:20:00contributes to that and that that is
01:20:03likely why there there's tolerance
01:20:05that people see so anecdotally.
01:20:10Nope. Four to seven days after
01:20:13a dose is required before.
01:20:17Psychedelics have an effect so.
01:20:21So I have a question about the
01:20:23beautiful graph with all of the
01:20:25metabotropic receptors on the
01:20:27right and different psychedelic
01:20:28compounds along the top from Marilee.
01:20:31Thomas says that it looks like
01:20:34M2M3 and M4 had no psychedelic
01:20:36activity and is that correct?
01:20:38Yes, she says she's surprised 'cause
01:20:41she thought muscarinic receptors
01:20:42were all activated by muscarine and
01:20:44it has hallucinogenics properties.
01:20:45And can you comment on that?
01:20:48Yeah so.
01:20:50Their hallucinogenic, but not psychedelic.
01:20:53So there is there.
01:20:55Is this distinction.
01:20:56We we in the field, make between a drug,
01:20:58that psychedelic and drug,
01:21:00that solution, new genics.
01:21:01So many drugs are hallucinogenic.
01:21:03As I said, Salvador and Ibogaine.
01:21:07Scope, alameen etc.
01:21:08And then there are drugs that
01:21:10are psychedelic and psychedelic.
01:21:13Drugs are five HT two agonist so.
01:21:16But good question.
01:21:19And then a question about signaling and
01:21:21and it sounds like different ligands
01:21:24induce different signaling responses.
01:21:26How do naturally occurring agonists
01:21:29compare, e.g LSD versus masculine?
01:21:34Ah. There are differences.
01:21:40And, uh. We're putting together a big
01:21:43paper where we're looking at all of these.
01:21:46All I can say is every compound is
01:21:48sort of unique and it depends on how.
01:21:52Uhm, at what level you look at it so,
01:21:55but it's I would say it's not clear
01:21:58yet that we're able to pick anything
01:22:00up that separates psychedelic
01:22:02for non psychedelic 2 agonist. So
01:22:05that question was from Zoran
01:22:07Similou who also says that five
01:22:09HT 2A is also an autoreceptor.
01:22:11In some serotonin synapses,
01:22:13and one proposal has been that
01:22:15blocking the autoreceptors might
01:22:18enhance serotonin transmission and
01:22:20therefore help antidepressant response.
01:22:23So can you sort of speculate about
01:22:25how LSD and other experimental
01:22:27agonists would fit into that?
01:22:30That aspect of the theoretical picture,
01:22:32especially in terms of?
01:22:35I'm not aware. Of any. Data.
01:22:40Any reliable data that the five HT 2A
01:22:43receptor is an inhibitory autoreceptor
01:22:46at any synapse its excitatory.
01:22:50Uh. And we actually only find it.
01:22:56So we we published a large number
01:22:58of papers on the localization of
01:23:01five HT 2A receptors by EM. In fact,
01:23:04we've never found it presynaptically.
01:23:06It's always been post synaptically so.
01:23:12So I I don't know about that data,
01:23:13so I can't comment on it.
01:23:17Great, so I think it's 11:40,
01:23:21so we should. Maybe stop it there.
01:23:24It has been a pleasure to
01:23:26spend this time with you.
01:23:27I just wanted to let you know that
01:23:29Doctor Agajanian was able to join
01:23:30us for part of the great great and
01:23:33I I I can send you his email if you
01:23:35want to reach out to him afterward.
01:23:37I want to thank everybody for your great
01:23:39questions and for being with us today.
01:23:40So thank you Brian.
01:23:42Oh, and can you send me a link
01:23:45so that I can meet with the with
01:23:47the students and everybody else?
01:23:49Absolutely I'll do that right now.
01:23:50Thank you. Bye bye.