Early Motor Development and Cerebral Cortical Morphology in Rats Exposed Perinatally to Alcohol

Abstract

Specific tests of early motor development and cerebral cortical morphology were studied in rats born from alcohol-fed mothers, pair-fed mothers, and ad libitum controls (either liquid or pellet diets). Liquid Bio-Serv diets were used. Alcohol feeding began on day 5 of pregnancy and ended on day 10 postpartum. The weight gain of the pups after birth was drastically reduced compared with pair-fed and other control groups; however, removal of the alcohol on day 10 postpartum resulted in an upswing of the growth curve that paralleled control groups. Between days 2 and 21 (postnatal) three behavioral tests of motor function were performed. Righting reflex (time for an animal to return to all four feet after being placed on its dorsum) was slightly delayed but the delay was not significant. Negative geotaxis (time for an animal to rotate 180 degrees from a head-down position on an inclined plane), and reflex suspension (time an animal maintained its grip on a crossbar) were significantly delayed (approximately 2 days) in offspring from alcohol-fed mothers. In the frontal cortex the offspring of alcohol-treated mothers, a marked decrease (approximately 25%) in thickness of Lamina VI was found while the other Lamina (I-V) were less altered. These results indicate that the effect of alcohol on the frontal cortex is related to a significant delay in motor development of reflex suspension and negative geotaxis since both of these require frontal integration.