Conditioned taste aversions induced by alcohol and lithium in rats selectively bred for ethanol neurosensitivity

Rats that were selectively bred for differences in alcohol-induced sleep time (alcohol neurosensitivity) were tested for differences in formation and extinction of alcohol- and LiCl-induced conditioned taste aversions. Male rats bred for high, control, or low alcohol sensitivity (HAS, CAS, and LAS rats, respectively) were deprived of water and given daily 30 min access to water for a baseline period of 7 days. Rats were then given a novel 0.125% sodium saccharin solution, followed by an intraperitoneal injection of either saline, 2 g/kg of ethanol (at 10% w/v), or 50.9 mg/kg of LiCl (0.15 M) on 3 conditioning days. Each saccharin exposure was followed by a recovery day of access to water. The ethanol-induced saccharin aversion extinguished more rapidly in LAS rats than in CAS or HAS rats (p < 0.05), but LiCl conditioned equivalent aversions in each group. Also, ethanol injection results in large differences in observed resting behavior in these rats (HAS > CAS > LAS), but LiCl injection produced no reliable group differences in resting. The weaker alcohol-induced taste aversion in LAS rats accords with their previously measured higher oral consumption of alcohol (Kulkosky et al., Alcoholism 17:545-551, 1993) and the idea that alcohol intake is limited by an expectancy of postingestive consequences. The weaker ethanol-induced aversion in LAS rats reflects selective breeding of an alcohol-specific trait and not a general difference in aversive conditioning or chemical neurosensitivity.