Projection-specific Proteomics in Striatum and Its Glutamatergic Afferents in Incubation of Craving to Psychostimulants (Cocaine and Methamphetamine)

Marina E. Wolf and Xuan (Anna) Li, Rosalind Franklin University of Medicine and Science and Behavioral Neuroscience Branch, National Institute on Drug Abuse

Relapse to drug use, which can occur even after a long period of abstinence, is a critical problem in treating addiction. To study neurobiological mechanisms underlying drug relapse, we have been using a rodent model termed incubation of drug craving, which refers to the progressive intensification (‘incubation’) of cue-induced drug craving during abstinence/withdrawal from drug self-administration. Incubation of craving has been observed across several drug classes in rodents and more importantly, it has also been demonstrated in human drug users.

Previously, we and others have demonstrated the important role of glutamate transmission in striatum in incubation of craving to psychostimulants. For example, the Wolf lab has shown that incubation of craving for both cocaine and methamphetamine (meth) involves strengthening of excitatory synapses in nucleus accumbens (NAc) through incorporation of high conductance calcium permeable AMPA receptors (CP-AMPARs). However, Dr. Li’s postdoctoral work in the Shaham group has shown that the circuitry beyond the NAc appears to differ for cocaine and meth. For incubation of meth craving, Dr. Li’s work has recently demonstrated an important role for glutamatergic input from thalamus (anterior intralaminar nucleus of thalamus; AIT) to dorsomedial striatum (DMS). Additionally, important roles for prefrontal cortex (PFC) and basolateral amygdala (BLA) projections to the NAc have been demonstrated with cocaine.

In this pilot grant, we aim to characterize protein expression during incubation of craving to cocaine and Meth in a projection-specific manner. We will focus on projections strongly implicated in regulation of incubation for each psychostimulant (cocaine: BLA to NAc core; meth: AIT to DMS). We will achieve projection specificity at both the cell body and synaptic level. At the cell body level, we will combine retrograde transporting AAV virus and fluorescent-activated cell sorting to label and sort BLA and AIT neurons that project into NAc core or DMS, respectively.  At the synaptic level, we will combine anterograde transporting AAV virus expressing a membrane-tethered extracellular tag, subcellular fractionation and immunoprecipitation to enrich for synaptoneurosomes postsynaptic to a particular pathway (synaptoneurosomes in NAc postsynaptic to BLA inputs; synaptoneurosomes in DMS postsynaptic to thalamic inputs). Overall, this proposal will help us gain insight into cellular mechanisms underlying the persistent vulnerability to drug relapse that makes addiction so difficult to treat.