Intermittent high-dose ethanol exposure increases ethanol preference in rats

Alcohol use disorders have both high social and economic costs and are among the leading causes of preventable death in the United States. Understanding the factors that contribute to escalation of alcohol intake is important in developing effective treatments for this problem. This study further characterizes the effects of limited intermittent exposure to high levels of alcohol on the preference for alcohol consumption over other incentives.

Fourteen male, Sprague-Dawley rats were trained to consume ethanol in a gelatin vehicle. They were then given free access to both ethanol gelatin and plain gelatin during daily choice periods interspersed with nonchoice periods (only plain gelatin access). After baseline ethanol preference was established, half of the rats were given eight injections of 3 g/kg ethanol during nonchoice periods (spread out over about 2 months), and the other half received saline injections. Ethanol preference was measured during subsequent choice periods.

Intermittent ethanol injections increased ethanol preference from 21% (SEM = 2.3%) of their total gelatin consumption during the first choice period to 46.8% (SEM = 3.4%) during the third choice period. The saline-treated rats had no significant change in ethanol preference. In addition, the ethanol-treated rats exhibited higher ethanol intake than saline-treated rats when ethanol gelatin was the only choice available.

The results indicate that intermittent exposure to sedative doses of ethanol leads to an increased ethanol preference in rats. This suggests that occasional high-dose alcohol exposure could be an important contributor to the development of enhanced ethanol intake, which may affect the incidence of chronic alcoholism.