Ethanol-stress interaction on dopamine metabolism in the medial prefrontal cortex

The effect of foot-shock and ethanol (2 g/kg per os) and the combination of the two on dopamine (DA) metabolism in the medial prefrontal cortex (MPFC) was studied in rats. Electric foot-shock stress (20 min stimulation) decreased DA concentration by 30% and increased dihydroxyphenylacetic acid (DOPAC) concentration by 65%. Ethanol (2 g/kg orally) decreased DA concentration by 20%, but, unlike foot-shock, failed to modify DOPAC levels. Neither treatments modified homovanillic acid (HVA) levels. The combination of ethanol (30 min before shock) and foot-shock produced about a 50% depletion of DA content and 30% increase in HVA, but no change in DOPAC levels. It is suggested that both ethanol and foot-shock activate DA release in the MPFC, but ethanol decreases DA retrieval by nerve terminals and, therefore, prevents intraneuronal deamination of the amine.