Nicotinic Acetylcholine Receptors in Anxiety and Depression

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DESCRIPTION (provided by candidate): Alterations in nicotinic cholinergic signaling in the brain have been implicated in numerous diseases and disorders, such as Alzheimer's disease (AD), autism, anxiety and depression. In addition, studies using mice lacking specific nicotinic receptor subunits have implicated these receptors in both anxiety and depression. Therefore, nicotine and subtype-specific nicotinic drugs present a rich area for investigation of their therapeutic potential in these mental disorders. However, a dearth of ideal animal models and subtype- selective ligands that easily cross the blood-brain barrier have previously hampered inquiry into this area. Equipped with novel compounds and a variety of behavioral models, this grant aims to examine the behavioral effects of nicotine and the nicotinic partial agonists, varenicline and sazetidine-A, in models of anxiety and depression as well as elucidate the molecular and cellular underpinnings of these behaviors. Initially, the acute and chronic effects of these drugs will be investigated in models of anxiety and depression (e.g., the novelty-induced hypophagia test and the forced swim test). Additionally, the effects of acute and chronic administration of nicotine, varenicline and sazetidine-A on adult neurogenesis, which has been implicated as mechanism for antidepressant action, will be examined using a fluorescently-activated cell sorting (FACS) method to detect BrdU labeled cells in hippocampi from treated animals. Finally, radioligand binding and sequential immunoprecipitation assays will be utilized to determine what nicotinic receptor subtypes are altered by nicotinic ligand administration and, thus, may be responsible for these behavioral and neuronal effects. The goal of this research is to identify new potential therapeutic uses of these drugs for disorders such as anxiety and depression, investigate the molecular correlates underlying the behavioral effects, as well as examine and evaluate the most appropriate behavioral models for use in nicotinic drug discovery. This research may ultimately lead to new therapies for depression and anxiety disorders, as well lay the groundwork for application of nicotinic compounds in the treatment of mental disease and disorders.