EFFECTS OF CHRONIC ETHANOL EXPOSURE ON ORAL SELF-ADMINISTRATION OF ETHANOL OR SACCHARIN BY WISTAR RATS

The study of alcohol abuse traditionally has placed great emphasis on the development of tolerance and dependence as key factors, However, a nimal models of ethanol self-administration in dependent rats have bee n difficult to establish, caused in part by ethanol's aversive taste c ues and subsequent aversive effects (i.e., ''hangover'' malaise) that prevent substantial ethanol consumption, In this study, this problem w as addressed in animals trained to self-administer ethanol (10% w/v) i n a sweetened-solution fading procedure before induction of dependence and repeated exposure to withdrawal, Once stable rates of responding for ethanol were achieved, a palatable liquid diet containing 8.7% (v/ v) ethanol was introduced as the sole source of calories and fluid for one group of rats [ethanol diet (ED) group], A second group of rats r eceived a control diet with sucrose isocalorically substituted for eth anol (CD group). After 14-17 days of liquid diet exposure, the rats we re withdrawn once a week for 4 weeks and 8 hr into each withdrawal ses sion were allowed to self-administer ethanol or water for 60 min, As c ompared with CD rats, ED rats showed significantly greater intake of e thanol, but not water, No significant differences were found when sepa rate groups of ED/CD rats were allowed to self-administer an alternate reinforcer (0.0075% saccharin solution), Rats who consistently had bl ood alcohol levels (BALs) above 100 mg% at the time of withdrawal sust ained high levels of ethanol self-administration throughout the four w ithdrawal sessions, In contrast, rats who had an average BAL at withdr awal below 100 mg% showed progressive decreases in ethanol self-admini stration during repeated withdrawal episodes, The results demonstrated that chronic exposure to ethanol and repeated periods of abstinence a re accompanied by elevated rates of ethanol intake in certain animals, and the persistence of elevated self-administration behavior of indiv idual rats is predicted by their BAL at the time of withdrawal.