Sensorimotor maturation and alcohol responsiveness in rats prenatally exposed to alcohol during gestational day 8

On gestational day 8, pregnant Sprague-Dawley derived rats received two intraperitoneal injections of 0.015 ml/g body weight of a 24% v/v ethanol solution representing an absolute alcohol dose of 2.82 g/kg per administration (ETOH Group). Control females were injected with similar volumes of saline (SAL Group) or did not receive any type of intraperitoneal administration of drugs (AC Group). In comparison with the control treatments, the ethanol treatment did not affect long-term maternal body weight gain during pregnancy, total length of gestation, probability of delivery, number of pups born per litter or the offsprings' preference of alcohol odor. Nevertheless, this ethanol insult was sufficient to significantly reduce body weights at birth and to retard the ontogeny of some sensorimotor patterns among offspring, as assessed through the Righting Reflex, Horizontal Screen Test and opening of the external auditory canals. The maturation of other reflexes (Cliff Aversion and Negative Geotaxis) appeared to be retarded indirectly as an outcome of the maternal injection procedure, with ETOH and SAL pups exhibiting similar developmental delays when compared with AC animals. During adulthood, rats prenatally exposed to alcohol exhibited a decreased hypothermic response to an intoxicating dose of alcohol as well as significant increases in voluntary alcohol consumption in comparison with both control conditions. Collectively, these results suggest that relatively acute alcohol exposure early in gestation may not only affect normal patterns of development but also later responsiveness to this pharmacological agent.