Effects of self-administered ethanol or water preloads on appetitive and consummatory behavior in the...

Ethanol intake control in the selected alcohol-preferring lines of rats appeared to have shifted in some lines for both increased ethanol seeking and increased consumption once ethanol was available. It was unknown whether a small preload of ethanol would alter either the seeking or the consumption in a selected line. This study examined this issue.

Alcohol-preferring (P) rats from Indiana University School of Medicine were initiated to drink ethanol using a sucrose-substitution procedure and a single daily limited-access trial. Following 30 responses on a lever, a sipper tube containing 10% ethanol extended into the operant chamber for 20 minutes. Self-administered ethanol and water preloads were tested prior to either a regular session or an extinction session. In extinction sessions, no access to the sipper tube occurred, and the number of responses occurring during 20 minutes was taken as a measure of ethanol seeking.

The ethanol and water preloads had no effect on the following ethanol consumption at any time during the experiment. However, the first two ethanol preloads significantly reduced extinction responding, which did not recover to the levels observed prior to the preload tests.

The data support the conclusion that ethanol seeking in the P rat can be influenced by environmental history, whereas consummatory behavior appears to be under more explicit genetic control. This gene-environment interaction suggests that, in the P rat, seeking behavior, initially set at higher levels than observed for nonselected lines, can be modified by certain environmental experiences.