Failure of Stress of Electric Shock to Increase Ethanol Intake in Rats

Abstract

To determine the effects on ethanol selection of a 14-day period of stress produced by intermittent shock (0.7 ma for 2.5 sec) delivered to the floor of individual cages, 28 Purdue Wistar rats (aged 130 to 160 days) were randomly assigned to experimental conditions as follows: 7 rats restricted to 12% ethanol for 20 days (acclimated) then given shock 6 times/hr on a variable interval schedule; 7 controls acclimated to 12% ethanol for 20 days but not given shock; 7 nonacclimated rats which received shock once/hr. on a fixed interval schedule; 7 nonacclimated controls which received no shock. Selection-avoidance functions of each animal were obtained by providing a 3-bottle randomized 3-position choice during the shock period: tap water; tap water with alcohol in daily increasing concentrations in 1% steps from 3 to 12%, then in 2% steps to 20%; and an empty "dummy". The results showed no significant differences in ethanol intake between the shocked and control rats in both acclimated and nonacclimated groups. The over-all intake of ethanol (4 to 8 g) was similar in both acclimated and nonacclimated groups. The total amount of ethanol ingested over the test period was 167.7 g by the shocked group and 160 g by the nonshocked, independent of acclimation. The use of electric shock as an experimental stressor for examining factors influencing ethanol selection in rats is questioned.