The expression and physiological properties of receptors, ion channels and transporters shape the electrical and biochemical properties of individual neurons and neural circuits. These membrane proteins are targets for drugs for the treatment of neurological conditions and also interact with addictive drugs such as nicotine, opioids, cocaine and amphetamines. Modern electrophysiological approaches allow the analysis of single receptors and ion channels in real time, revealing their sensitivity to transmitters and drugs, changes in membrane voltage, and physical stimuli such temperature and pressure. Advanced cellular imaging techniques use fluorescent indicators to study ion flux and voltage changes across the neuronal cell membrane. Molecular, biochemical and structural approaches reveal functional domains within ion channels and transporters interacting with neurotransmitters, therapeutic drugs and other neuronal proteins.
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Physiological acoustic stimulation reduces the phosphorylation state of the Kv3.1 potassium channel in auditory brainstem neurons. Images show the levels of immunostaining for Kv3.1 specifically phosphorylated at serine 503 in two areas of the brainstem in an animal exposed to sound to one ear only. The nuclei at the top right and bottom left were stimulated by the sensory input and have lower levels of phosphorylated channels (from Song et al., Nature Neurosci., 8: 1335-1342, 2005)