Enhanced ethanol intake in preweanling rats following exposure to ethanol in a nursing context

Abstract

Several studies have confirmed that diet selection patterns of adult rats are at least partially estabilished as a result of early experiences with food‐related stimuli present in the milk of a lactating female (e.g., Capretta & Rawls, 1974; Galef & Clark, 1972; Galef & Henderson 1972). The present experiments were designed to investigate whether preweanling rats would similarly modify their acceptance of an ethanol solution following exposure to this cue in a nursing context. In Experiment 1, 8‐, 12‐, and 16‐day‐old rats were given ethanol, delivered intraorally in compound with milk, while given the opportunity to suckle an anesthetized dam. Subsequent testing revealed that 12‐ and 16‐day‐old subjects evidenced enhanced intake of the ethanol relative to controls, while 8‐day‐olds did not. Finally, the oldest (16 days of age) subjects also expressed a conditioned aversion to the milk when tested 24 hr after conditioning and ethanol‐ingestion testing. Experiment 2 demonstrated that the critical factor for ethanol conditioning was the opportunity to suckle, rather than the simultaneous presence of milk. Finally, the aversion to milk observed in Experiment 1 was shown to have resulted from long‐delay learning, due to the ingestion of a sufficient dose of ethanol during testing to serve as an aversive unconditioned stimulus (Exp. 3) © 1993 John Wiley & Sons, Inc.