McNeill D L, Shew R L, Papka R E
Department of Anatomical Sciences, University of Oklahoma, Oklahoma City.
Dev Neurosci. 1991;13(3):171-5. doi: 10.1159/000112154.
Previous studies have demonstrated that exposure to ethanol during development delays the rate at which axons in certain central nervous system tracts acquire myelin. This delay appears to be related to an alteration in oligodendrocyte function and not to an aberrancy in axon size or number. The present study was designed to determine if alterations similar to those observed in the central nervous system also occur in peripheral nerves, specifically the L2 dorsal root. Dams were fed either an ethanol-containing or control liquid diet 2 weeks prior to pregnancy and throughout gestation. The pups born to the pregnant dams were artificially reared from postnatal day (PD) 4 to PD 10 on a similar ethanol-containing or control diet. The pups were sacrificed on PD 10, L2 dorsal roots removed and processed for electron microscopy. The numbers of axons in various states of myelination were quantified. No difference was observed in the number of unmyelinated axons in the L2 dorsal roots from ethanol-exposed and control pups. In roots from ethanol-exposed pups, there was a significant decrease in the number of axons possessing myelin arranged in compact lamellae, but a significant increase in the number of axons surrounded by myelin lamellae in which the Schwann cell cytoplasm had not yet been extruded (noncompact). However, when the number of axons possessing noncompact myelin and a compact myelin sheath were summed, no significant difference was observed. These data suggest that the delay in myelination following ethanol exposure may be a ubiquitous phenomenon throughout the nervous system.
先前的研究表明，发育过程中接触乙醇会延缓某些中枢神经系统 tracts 中轴突获得髓鞘的速度。这种延迟似乎与少突胶质细胞功能的改变有关，而与轴突大小或数量的异常无关。本研究旨在确定在中枢神经系统中观察到的类似改变是否也发生在外周神经，特别是 L2 背根中。在怀孕前 2 周及整个妊娠期，给孕鼠喂食含乙醇或对照液体饮食。怀孕母鼠所生的幼崽在出生后第 4 天（PD）至第 10 天，用类似的含乙醇或对照饮食人工饲养。在 PD 10 处死幼崽，取出 L2 背根并进行电子显微镜处理。对处于不同髓鞘化状态的轴突数量进行量化。在暴露于乙醇的幼崽和对照幼崽的 L2 背根中，未观察到无髓鞘轴突数量的差异。在暴露于乙醇的幼崽的根中，具有紧密排列的髓鞘的轴突数量显著减少，但被髓鞘板层包围且施万细胞胞质尚未挤出（非紧密）的轴突数量显著增加。然而，当将具有非紧密髓鞘和紧密髓鞘的轴突数量相加时，未观察到显著差异。这些数据表明，乙醇暴露后髓鞘化延迟可能是整个神经系统中普遍存在的现象。
