The effect of chronic maternal alcohol consumption on the development of central nervous system myelin subfractions in rat offspring

Abstract

Female Sprague-Dawley rats were pair-fed using isocaloric control or 6.6% (v/v) ethanol liquid diets for one month prior to conception and throughout gestation. The development of three central nervous system (CNS) myelin subfractions was examined in the 18- to 54-day-old offspring (control and ethanol pups) of control and ethanol-treated females. During the same age period, the in vivo incorporation of [3H] leucine into myelin subfraction proteins and of [14C] glucose into myelin subfraction lipids was also studied.Despite the fact that the ethanol pups consistently had smaller brain and body weights than normal rats, 18- and 25-day-old ethanol pups had more CNS myelin than control pups. However, the increased myelin content was due solely to an excess of the chemically and morphologically immature heavy myelin fraction. Fifty-four-day-old ethanol pups had a small deficit of total CNS myelin.Developing ethanol pups also demonstrated abnormal rates of incorporation of [3H] leucine and [14C] glucose into the myelin subfractions. At 18 and 25 days, the ethanol pups incorporated more of both precursors into all fractions of myelin, while at 54 days they demonstrated decreased incorporation.Although the quantity and rate of synthesis of individual myelin subfractions was abnormal in ethanol pups, the protein composition of the separated subfractions was normal. In addition, the ethanol pups had a normal distribution of 3H and 14C radioactivity, in separated myelin subfraction proteins and lipids, respectively.The results of the present study suggest that the consumption of a 6.6% (v/v) ethanol liquid diet prior to conception and throughout gestation resulted in a premature onset and slow-down of active myelination.