SENSITIVITY OF NUCLEUS-ACCUMBENS NEURONS IN-VIVO TO INTOXICATING DOSES OF ETHANOL

The nucleus accumbens septi (NAcc) is considered an important componen t of the final common pathway involved in the reinforcing properties o f ethanol. We studied the effects of intraperitoneal administration of ethanol on spontaneous, glutamate-activated, and fimbria-activated NA cc neurons in acute anesthetized and freely moving unanesthetized rats . Ethanol significantly reduced the firing rate of spontaneous and glu tamate-activated NAcc neurons in both electrophysiological preparation s. Stimulation of the ipsilateral fimbria evoked single-unit activity in NAcc neurons with two characteristic latencies (early, 7.21 +/- 0.7 4 msec; late, 18.24 +/- 0.66 msec). Intoxicating doses of ethanol inhi bited the recruitment of late, but not of early, fimbria-activated NAc c neurons. These data demonstrate electrophysiological evidence for th e existence of neurons in the core region of the NAcc that are sensiti ve and insensitive to acute systemic ethanol administration.