Prenatal cocaine exposure increases the reinforcing strength of oral ethanol in C57 mice

Abstract

Pregnant C57BL/6J mice received daily injections of 10 mg/kg cocaine or saline during gestation days 12-18. Although a previous report indicated that this dose of cocaine did not alter maternal weight gain, birth weight, growth, or adult weight, the present study indicates that it did increase the reinforcing efficacy of ethanol in fully mature male and female offspring. Food-deprived subjects responded on fixed ratio-8 (FR-8) and progressive ratio-2 (PR-2) schedules of reinforcement for 10-, 5-, or 3-s access to various ethanol concentrations. The male prenatal cocaine-exposed mice tended to have higher response totals under the FR-8 schedule and higher breaking-points during some PR-2 tests, with the greatest difference between groups occurring at the highest ethanol concentration. The female prenatal cocaine-exposed mice consumed more ethanol than controls during most of the tests, and had higher breaking-points compared to controls during the more demanding PR-2 tests. Thus, it appears that a dose of cocaine that has no observable effect on many maternal and perinatal outcome measures can alter systems mediating ethanol reward.