6-OHDA-Lesions of the Nucleus Accumbens Disrupt the Acquisition but not the Maintenance of Ethanol Consumption in the Alcohol-Preferring P Line of Rats

The aim of the present study was to determine whether reduction of dopamine (DA) innervation to the nucleus accumbens (ACB) alters the maintenance and/or acquisition of ethanol drinking in female alcohol‐preferring P rats. Compared with sham‐lesioned animals, bilateral microinjections of 6‐OHDA (12 μg/2.4 μl/site) into the ACB did not alter the consumption of 10% ethanol in rats that had prior experience of ethanol drinking, with both sham‐ and 6‐OHDA‐lesioned groups recovering to presurgical consumption levels at similar rates. On the other hand, the identical lesion procedure disrupted the acquisition of ethanol intake in rats with no ethanol‐drinking experience prior to the lesions. A sham‐lesioned group attained an ethanol intake of approximately 7 g/kg/day in 1 week, which was maintained over the following 2‐week period, while the ethanol intake of the 6‐OHDA‐lesioned group was approximately 60% lower after 1 week and 30% lower at the end of 3 weeks. DA content of the ACB was 60% lower in both groups of the 6‐OHDA‐treated rats compared with the controls. The results suggest that different neural mechanisms may underlie the acquisition and maintenance of ethanol drinking behavior; the ACB DA system appears to play an important role in the acquisition of ethanol drinking.