Nicotinic Receptors in the CNS
The pivotal role of CNS nicotinic acetylcholine receptors
(nAChRs) in tobacco addiction has focused our attentions on understanding the overall
function of these receptors in the brain both under physiological and diseased conditions.
nAChRs are ligand-gated ion channels composed of five individual protein subunits that
cause neuronal excitation when bound and activated by synaptically released
neurotransmitter, acetylcholine, or exogenous drugs like nicotine. Molecular biological
studies have characterized at least ten receptor subunits that can be assembled together
in numerous combinations giving rise to a wide variety of nAChRs with distinct functional
roles. It is because of this diversity that nAChRs have been implicated in a range of CNS
behaviors from pain sensation to learning and memory, and multiple pathological states
such as epilepsy and schizophrenia.
High-resolution electrophysiological (patch-clamp)
techniques combined with intracellular Ca2+ measurements provide the most
powerful way of examining these receptors. The physiological and pharmacological
properties of single and multiple nAChR channels in isolated membrane patches and whole
cells can be fully resolved using these methods. The roles of nAChRs at both pre and
postsynaptic zones of central synapses can be studied by recording from visually
identified neurons in brain slice preparations. In collaboration with Dr. Michael W. Quick
the electrophysiology is complemented by molecular biological approaches that allow the
expression and characterization of known cloned nAChRs and the determination of nAChR RNAs
from CNS neurons (by single cell RT-PCR). Thus, a full array of methods are available to
address the following types of questions. How do nAChRs contribute to synaptic
transmission and plasticity? How are nAChRs regulated by intracellular Ca2+,
phosphorylation and the cytoskeleton? How does chronic nicotine affect the long-term
functioning of the various nAChRs?
Robin A.J. Lester received his Ph.D. in
Pharmacology from the University of Bristol, UK in 1988. Following a Research Assistant
Professor position at Baylor College of Medicine, he joined UAB in 1995. He is presently
an Associate Professor of Neurobiology.
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