Severity of alcohol-induced deficits in rats during the third trimester equivalent is determined by the pattern of...

The pattern of alcohol exposure has been suggested to be an important determinant of fetal alcohol effects. Rats were exposed to alcohol and reared artificially on postnatal days (PD) 4-10. A uniform alcohol exposure group received alcohol (6.6 g/kg/day) in 12 daily feedings (every 2 hrs) resulting in stable BACs below 100 mg/dl. A condensed alcohol exposure group also received 6.6 g/kg/day but the alcohol was concentrated in 4 of 12 daily feedings giving peak BACs above 400 mg/dl. Condensed alcohol exposure induced a large degree of microencephaly on PD 10 which was still present on PD 90. Uniform exposure caused a mild degree of microencephaly on PD 10 which could not be detected at PD 90. Correlated with these brain changes were changes in behavior during development. Condensed exposure to alcohol increased locomotion during postnatal days 14 to 20. Condensed alcohol exposure caused delays in the development of balancing ability and coordinated hindlimb movements. Thus, the pattern of alcohol exposure appears more critical than the dose in determining the degree of damage inflicted by alcohol to the developing central nervous system.