Central nervous system myelination in rats exposed to ethanol in utero.

Pregnant rats were pair-fed using isocaloric control or 6.6% (v/v) ethanol liquid diets. At 18, 25, and 53 days, the in vivo incorporation of [3H] leucine and [14C] glucose into proteins and lipids of three central nervous system (CNS) myelin subfractions was examined in the offspring (control and ethanol pups) of control and ethanol-treated females. With few exceptions, the pattern of CNS myelination appeared near-normal in the ethanol pups. The ethanol pups had brain weights and total myelin protein content within the normal range. In addition, the amount of protein in light, medium, and heavy myelin was normal at 18 and 25 days. However, the ethanol pups had an excess of the chemically and morphologically immature heavy fraction at 53 days. The incorporation of [3H] leucine and [14C] glucose into myelin subfractions and separated proteins and lipids was similar in control and ethanol pups. The findings of near-normal CNS myelination in the offspring of female rats fed an ethanol liquid diet during gestation differ from our previous findings of a premature onset and slowdown of active CNS myelination in the offspring of female rats that consumed an ethanol liquid diet for one month prior to conception as well as during gestation.