Ethanol effects on dopaminergic "reward" neurons in the ventral tegmental area and the mesolimbic pathway

Dopaminergic (DA) neurons in the ventral tegmental area (VTA) provide the DA innervation of the nucleus accumbens. This mesolimbic DA pathway is important for the reinforcing effects of alcohol and plays a central role in alcohol-related behaviors. This Research Society on Alcoholism symposium included a discussion of the acute and chronic effects of ethanol and ethanol withdrawal on DA VTA neurons. The experiments that were discussed ranged from studies in the freely moving behaving rat and electrophysiological studies in vivo, to electrophysiological studies in brain slices and acutely dissociated DA VTA neurons, to neurochemical studies that explored the cellular basis of ethanol's actions. Because ethanol's effects on this reinforcement pathway are critically important for voluntary intake of alcohol and alcohol addiction, this symposium report may be of interest to both basic science and clinical researchers in the alcohol field. This symposium focused on effects of ethanol on the mesolimbic dopamine pathway, specifically the VTA and the nucleus accumbens. The organizer/co-chairs were Sarah B. Appel and Mark S. Brodie. The presentations were (1) Introduction, by Mark S. Brodie; (2) Reinforcing Actions of Alcohol in the Ventral Tegmental Area: Intracranial Self-Administration Studies, by William J. McBride; (3) A Possible Mechanism Mediating the Direct Excitation of Dopaminergic Ventral Tegmental Area Neurons by Ethanol, by Sarah B. Appel; (4) Effect of Chronic Ethanol and Withdrawal on Dopaminergic Ventral Tegmental Area Neurons: In Vivo Electrophysiological Studies, by Marco Diana; (5) Ethanol Induces Protein Kinase A Translocation Into the Nucleus, Cyclic AMP Response Element Binding Protein Phosphorylation, and Increases in Cyclic Adenosine Monophosphate-Dependent Gene Expression, by Ivan Diamond; and (6) Co-activation of Dopamine D₁ and D₂ Receptors Is Necessary for Dopamine-Mediated Increases in Firing Activity in Nucleus Accumbens Neurons, by Antonello Bonci.