Effects of access to a running wheel on food, water and ethanol intake in rats bred to accept ethanol.

Rats from the University of Indiana lines bred to accept ethanol (P rats) and not to accept ethanol (NP rats) were divided into two groups of 3 rats per group. The first group of P and NP rats was given free access to food, water and 5% (w/v) ethanol 24 h a day. After food, water and ethanol intake stabilized, a running wheel was introduced into the cage. Access to the running wheel decreased ethanol intake and increased water intake in P rats. When the running wheel was locked in place, ethanol intake by P rats increased, but when the wheel was unlocked again, no decrease in ethanol intake occurred. Access to the running wheel did not affect food, water or ethanol intake in NP rats. The decrease in ethanol intake when the running wheel was introduced was replicated in the second group of P rats exposed to 5% ethanol and later to 10% ethanol. The decreases in ethanol consumption produced by the introduction of a running wheel for this genetic model of alcohol consumption are similar to those previously reported using schedule-induced polydipsia to induce ethanol intake.