Age-related differences in sensitivity to alcohol in the rat

Female F344 rats of three different ages (4, 13, and 25 months) were tested for sensitivity to the ataxic, hypothermic, and hypnotic effects of injected ethanol. Challenges with ethanol sufficient to produce similar blood alcohol concentrations (BACs) in all age groups at the time of testing were observed to produce greater ataxia in old rats (25 months > 13 months > 4 months). Old rats also were observed to recover the righting reflex at lower BACs than those present in young or middle age rats. BAC at a target rectal temperature of 36 degrees C was observed to be lower in old than in young or middle-age rats when measured as body temperature was falling after doses of 3.0 g/kg to old and 3.5 g/kg to young and middle rats. However, no differences among groups in BAC at target temperature (36 degrees C) were observed as body temperature was recovering from peak hypothermia back up to 36 degrees C. With the exception of the last observation cited, these findings appear to confirm and extend earlier reports of increased target tissue sensitivity to ethanol with advancing age in rodents.