ETHANOL MODULATES COCAINE-INDUCED BEHAVIORAL-CHANGE IN INBRED MICE

We recently conducted a study of the behavioral effects of combined co caine and ethanol in genetically defined mice. Male and female C57BL/6 (B6) and DBA/2 (D2) were tested in an automated activity monitor on 2 consecutive days. On day 1, all animals received an IP injection of s terile saline and were placed into the activity monitor for 30 min. Be haviors measured were total distance traveled, stereotypy, nosepokes, and wall-seeking. On day 2, all animals were tested again for 15 min f ollowing injection of one of the following: saline, 10% v/v ethanol at 2.0 g kg(-1) or 2.0 g kg(-1) ethanol plus 5, 15, or 30 mg kg(-1) coca ine. Cocaine alone at the same doses was injected into separate groups of animals. For the B6 strain, the overall effect of ethanol was to r educe cocaine induced locomotor stimulation; no consistent effect of e thanol on cocaine-induced locomotion was observed in D2 mice. Cocaine induced inhibition of nosepokes in both strains and sexes was partiall y reversed by ethanol. Ethanol also partially reversed cocaine-elevate d stereotypy in both strains and both sexes. In B6 mice, cocaine-incre ased wall seeking tended to be reversed by coadministration of ethanol , whereas no consistent pattern was observed in the D2s. Results from this study suggest that the several measures affected by cocaine (loco motor activity, stereotypy, exploration, thigmotaxis) were, in turn, d ifferentially affected by concurrent treatment with ethanol. Furthermo re, our results point to genetic-based differences in ethanol's effect s on cocaine-related behaviors. We address the implications for combin ed ethanol and cocaine use in humans. (C) 1998 Elsevier Science Inc.