Abstracts - Speakers

First Annual Waggoner Center Advance - March 22, 2013

Richard Morrisett, PhD

Professor of Pharmacology & Toxicology

Accumbal Plasticity: An Engram for Ethanol Experience

Alterations in the sub-synaptic trafficking of AMPA-subtype of glutamate receptors in medium spiny neurons of the nucleus accumbens may constitute a critical neuroadaptive process encoding responses to a variety of positive and negative reinforcers. In this symposium presentation, I will discuss our most recent work using GENSAT drd1-eGFP mice and ex vivo whole-cell slice-patch electrophysiology to quantify how shell NAc D1+ and D1- MSNs differentially encode a single four-day bout of chronic intermittent ethanol experience. We observed in ethanol-naïve mice that D1+ MSNs are intrinsically more excitable than their D1- counterparts, and most notably, that long-term depression (1 Hz-LTD) of glutamatergic excitatory transmission appeared to be solely induced in D1+ MSNs and absent in ethanol-naive D1- MSNs. However, 24 hours following a repeated regimen of in vivo chronic intermittent ethanol (CIE) vapor exposure, 1 Hz-LTD was completely occluded in D1+ MSNs but yet now appeared present in D1- MSNs. Complete recovery of their respective baseline 1 Hz-LTD expression phenotype for both MSN-cell types gradually occurred over the ensuing two weeks of withdrawal from CIE vapor exposure. Therefore, it appears that glutamatergic metaplasticity of both types of MSNs may differentially encode neuroadaptation to ethanol experience, thus involving both the direct and indirect pathways of information processing through the shell of the nucleus accumbens.