The effects of neurotoxins 6-hydroxydopamine and 5,7-dihydroxytryptamine into the rat nucleus accumbens on the alcohol drinking behavior.

To elucidate the relationship between drinking behavior and brain monoamines in the brain rewarding system, the effects of injection of 6-hydroxydopamine (6-OHDA) and 5,7-dihydroxytryptamine (5,7-DHT) into the rat nucleus accumbens (ACC), which would affect dopamine- and indoleamine-containing neurons, respectively, on the rat alcohol preference score were examined. The 6-OHDA (4 micrograms/side)-treated rats showed a higher alcohol preference score for 2 weeks following the treatment, and a lowered dopamine (DA) level in the ACC and midbrain after ACC injection of 6-OHDA. On the other hand, although the serotonin (5-HT) and DA levels in the midbrain and 5-HT level in ACC were lowered after the injection of 5,7-DHT, the alcohol preference score was not significantly changed in the 5,7-DHT (4 micrograms/side)-treated rats. Taken together, these findings suggest that the alcohol drinking behavior is more influenced by the ACC DA activity than 5-HT activity. Changes in alcohol drinking behavior might be related to the compensatory mechanism for the rat to restore the original rewarding properties.