BENZODIAZEPINES ENHANCE THE CONSUMPTION AND PALATABILITY OF ALCOHOL IN THE RAT

This study examined the effect of the benzodiazepine, midazolam, on th e consumption and palatability of 6% ethanol in male Wister rats. In t he first experiment, it was found that midazolam (5 mg/kg) increased h ome cage ethanol drinking 0-2h after administration. Another intake ex periment, in which ethanol was infused directly into the oral cavity t hrough an indwelling catheter, also showed that midazolam (10 mg/kg) s timulated alcohol ingestion. The affective response to intraoral infus ions of ethanol (1 mi during 1 min) was subsequently monitored in benz odiazepine-treated rats. Taste reactivity testing showed that midazola m (5-10 mg/kg) significantly increased the occurrence of hedonic orofa cial responses and suppressed the number of passive drippings. A simil ar response pattern was observed following administration of diazepam (5mg/kg) and chlordiazepoxide (10 mg/kg), but not after exposure to ci s(Z)flupentixol (10 mg/kg). Midazolam also increased the incidence of hedonic responses in alcohol-naive rats with no previous access to eth anol in the home cages. Hedonic responsiveness did not appear to dimin ish with repeated benzodiazepine exposure: the behaviour of rats given five midazolam injections (10 mg/kg every second day) was similar to that shown by rats with no benzodiazepine pre-exposure. The increased hedonic response to ethanol induced by midazolam was blocked by pretre atment with the benzodiazepine receptor antagonist flumazenil (10 mg/k g), the latter drug exerting no effects on its own. The present result s suggest that benzodiazepines, by acting on GABAA receptors, may faci litate ethanol intake by increasing ethanol's taste hedonic properties .