ETHANOL AS A REINFORCER - A REVIEW OF LABORATORY STUDIES OF NONHUMAN-PRIMATES

This article reviews studies of ethanol self-administration in non-hum an primates. Between approximately 1960 and 1980 research programs at three university medical centers (Michigan, Minnesota and Baylor) esta blished that ethanol could function as a reinforcer when delivered eit her intravenously, intragastrically or orally. Variables such as sessi on length, dose and intermittent reinforcement schedules were examined , and tolerance and physiological dependence on ethanol were also stud ied. Procedures used to establish abused drugs as reinforcers via the intravenous, intragastric and oral route are also effective in the par ticular case of ethanol. Under conditions of limited access (e.g. 3 h per day), the variables that control behavior reinforced by ethanol ar e the same as those that govern behavior reinforced by other drugs. Mo reover, the functional relations between these variables and ethanol-r einforced responding are similar to the functional relations between t he same variables and other drug reinforcers. However, with continuous 24 h access to ethanol, differences appear with respect to other seda tive-hypnotic drugs. In contrast to these other drugs, intravenous eth anol use results in a suppression of food intake, weight loss, self-in itiated abstinence, and often, death. When intravenous and oral ethano l self-administration are compared, two important differences emerge: the maximum intakes via the intravenous route exceed the maximum intak es via the oral route, and, perhaps surprisingly, the doses required t o maintain responding are lower with the oral route. Studies since 198 0 have increased the scope of ethanol reinforcement research and also corroborated and extended earlier findings. In summary, ethanol can fu nction as an effective reinforcer for non-human primates.