Effects of repeated cocaine treatment on striatal dopamine release in alcohol-preferring AA and alcohol-avoiding ANA rats

Modulation of striatal dopamine (DA) release by acute or repeated cocaine t reatment was studied in the nucleus accumbens and caudate-putamen of alcoho l-preferring (AA, Alko Alcohol) and alcohol-avoiding (ANA, Alko Non-Alcohol ) rats. Cocaine (5-10 mg/kg i.p.) was administered daily for 4 days and the concentrations of extracellular DA measured by in vivo microdialysis on da ys 1 and 4 in the freely moving rats. The first administration of cocaine i ncreased DA concentration similarly in rats of both lines in both the nucle us accumbens and caudate-putamen. On the 4th day, the effect of cocaine was significantly larger in the nucleus accumbens of AA than in that of ANA ra ts, whereas no such enhanced effect of cocaine was found in the caudate-put amen of either line. The results suggest that mesolimbic DA release in resp onse to cocaine is sensitized more readily in AA than in ANA rats, which wo uld not only render the former more susceptible to alcohol, but to other dr ugs of abuse, and might explain our previous findings that AA rats are more susceptible to psychomotor sensitization than ANA rats.