ETHANOL INHIBITS SINGLE-UNIT RESPONSES IN THE NUCLEUS-ACCUMBENS EVOKED BY STIMULATION OF THE BASOLATERAL NUCLEUS OF THE AMYGDALA

We studied the actions of intoxicating doses of ethanol on excitatory inputs from the basolateral nucleus of the amygdala, a major afferent system projecting to the nucleus accumbens (NAcc). In view of the hypo thesized role of opioid receptors on the effects of ethanol on NAcc ph ysiology, we also explored whether naloxone modulates ethanol-induced suppression of NAcc excitability in halothane anesthetized and freely moving unanesthetized rats. Intraperitoneal administration of ethanol (1.2-1.4 g/kg) markedly suppressed a subgroup of amygdala-activated NA cc neurons. The ethanol-induced reduction in amygdala-activated NAco n eurons was not reversed by naloxone (5.0 mg/kg, intraperitoneally). Mo reover, naloxone had no effect on the supressive effects of ethanol on NAcc spontaneous activity in either halothane-anesthetized or unanest hetized freely moving preparations. These findings suggest that opiate mechanisms either are not participating or are not solely responsible for the inhibitory effects of acute intoxicating doses of ethanol on NAcc physiology.