CHRONIC ETHANOL, DOPAMINE ELECTROPHYSIOLOGY, AND CRAVING

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Craving for ethanol is an important factor for high rate of relapse during abstinence. In order to develop effective pharmacological treatment for alcoholism, it is important to understand neurological basis for craving. We have demonstrated a reduction in the spontaneous activity in dopaminergic (DA) neurons in the ventral tegmental area (area 10). This reduction may be the cause of decreased DA release and metabolism commonly observed during ethanol withdrawal period. Because activation of A10 DA system is proposed to mediate brain reward of addictive substances including ethanol, it is likely that this reduction in A10 DA neuron activity during ethanol withdrawal results in ethanol craving. The proposed studies in this application intent to use the electrophysiological approach to characterize the chronic ethanol's effects on the spontaneous activity of A10 DA neurons and the underlying mechanism. In order to understand the neuroadaptation process of A10 DA neurons to chronic ethanol treatment, experiments under Specific Aim l are designed to study the dose and time course effects of chronic ethanol treatment; The spontaneous activity of Al0 DA neurons will be examined during both the intoxication and initial withdrawal stages to provide information of corresponding changes to blood ethanol levels. Experiments under Specific Aim 2 will examine natural functional recovery of the spontaneous activity of A10 DA neurons during prolonged withdrawal period (abstinence). Results from our preliminary studies suggest that Al 0 DA neurons become inactivated because chronic ethanol treatment causes excessive depolarization which disrupts the action potential generation mechanisms. This hypothesis and the underlying cellular mechanisms will be studied with in vitro whole cell recording technique. The results obtained from this proposal will better our understanding in chronic ethanol's effects on A10 DA systems. Furthermore. the electrophysiological approach employed may be validated as a experimental model to explore possible therapeutic agents to alleviate craving for ethanol.