Determining the function of TRPC6 channels in a subpopulation of VTA dopamine neurons

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Project Summary/Abstract: Midbrain dopamine (DA)-producing neurons of the ventral tegmental area (VTA) play a critical role in modulating reward-seeking behavior. VTA-DA neurons are functionally and genetically heterogeneous, and genetic markers for neuropeptides and neuropeptide receptors can be used to isolate VTA subpopulations. Though distinct neuropeptidergic pathways have been shown to potently modulate DA neurons, the intracellular signaling pathways that act downstream of neuropeptide receptors are unknown. VTA-DA neurons that express the Gq-protein coupled receptor, tachykinin receptor 3 (Tacr3), are a minimally sufficient subpopulation of DA neurons that promote reward reinforcement behavior. Tacr3 activation has recently been shown to be dependent on transient receptor potential canonical (TRPC) channel signaling in the hypothalamus. TRPC type 6 (TRPC6) channels are enriched in DA neurons and are activated by stimulation of Gq-coupled receptor signaling. Therefore, I hypothesize that TRPC6 is likely the main type of TRPC channel in VTA-DA neurons that acts downstream of Tacr3 activation. To establish the role of TRPC6 in regulating the physiology and function of VTA-Tacr3 neurons, I propose to selectively mutate the Trpc6 gene to generate a loss of function in a cell-type specific manner within the VTA of adult mice using an advanced CRISPR/Cas9 genetic technology. I will perform ex vivo slice electrophysiology and slice calcium imaging (Aim 1), as well as in vivo recordings of calcium dynamics during a probabilistic discounting paradigm and progressive ratio motivational task (Aim 2). Determining the function of TRPC6 in VTA-Tacr3 neurons will provide important insights into the therapeutic potential of this understudied ion channel in the central nervous system.