INBRE-2 SINGLE-CHANNEL BASIS OF MODULATION OF HUMAN NEURONAL NICOTINIC RECEPTORS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Neuronal nicotinic acetylcholine receptors transduce binding of acetylcholine into channel opening, thereby linking presynaptic exocytosis with postsynaptic excitation. Errors in cholinergic transmission in the central nervous system underlie important disorders and diseases including Alzheimer's disease, schizophrenia, autism, depression and nicotine addiction. Neuronal nicotinic receptors exist as a diverse family of subtypes with distinct distributions and biophysical properties; however, the functional roles of these subtypes have not been defined for either normal or abnormal processes. A novel compound, desformylflustrabromide, potentiates the action of acetylcholine at a single class of nicotinic receptors and may therefore be of experimental and therapeutic use. The overall aim of this proposal is to use single-channel and fast drug application methods to examine the mechanism of action of desformylflustrabromide on the alpha4/beta2 class of human neuronal nicotinic receptors expressed in HEK-293 cells. Neuronal nicotinic receptors are activated by temporal profiles of acetylcholine concentration that depend on the location of the receptor relative to sites of exocytosis. Extrasynaptic receptors are activated by relatively low, tonic concentrations of acetylcholine, whereas subsynaptic receptors experience high (mM) concentrations that change over the course of hundreds of microseconds. We will therefore investigate the effects of desformylflustrabromide on receptors activated by both slow and fast agonist application profiles. Specifically, we aim to determine the effect of desformylflustrabromide on receptors activated by 1) a low concentration of acetylcholine and 2) a brief (1 ms) application of a high (1 mM) concentration of acetylcholine. The addictive effects of nicotine are mediated by the action of nicotine on alpha4/beta2 receptors of the mesocorticolimbic dopamine system. Desformylflustrabromide is therefore of potential use in smoking cessation therapy and as a pharmacological tool to investigate further the role of alpha4/beta2 receptors in nicotine addiction. We will therefore determine the effect of desformylflustrabromide on activation of alpha4/beta2 receptors induced by a low, "physiological" concentration of nicotine.