Individual Differences in Behavior and Alcohol Consumption in the Rat

Abstract

Six male and six female Sprague-Dawley mature rats were assigned to two groups of six animals each (three males and three females in each group). One group (Choice-Test) was given a choice of three drinking fluids in the home cage: a 3.4% alcohol solution by volume, a maltose solution equal in caloric value to the alcohol solution, and tap water, for 5 days (Choice Period). This group was then tested in five different experimental situations: an Escape Test (from home cage), and Open Area Test designed by Hall (21), a Tunnel Test devised by Stone (22), a Water Wading Test introduced by Parker (23), and a Bar Pressing Situation (20). The animals were tested for 5 days (Test Period). The other group (Test-Choice) was given the same treatment except that the Test Period preceded the Choice Period. All the animals were allowed a 3-week period of acclimation to the laboratory before experimental manipulation was begun. All behavioral measures were then correlated with the following criterion for ranking animals on alcohol consumption: Total volume of alcohol solution consumed divided by total volume of all fluids consumed during the Choice Period. Negative but nonsignificant correlations were found between alcohol consumption and defecation rate during behavioral testing. It was found that animals which left the home cage during the Escape Test readily and remained longer at the brightly lit entrance to the tunnel (while in the tunnel) drank more alcohol. Thus timidity, as measured by these behavioral responses, may be regarded as related to consumption of an alcohol solution in a choice situation.