Miller M W, Astley S J, Clarren S K
Research Service, Veterans Affairs Medical Center, Iowa City, Iowa 52246-2208, USA.
J Comp Neurol. 1999 Sep 13;412(1):123-31.
The effects of prenatal exposure to ethanol on the number of callosal axons were examined. Pregnant Macaca nemestrina were treated with ethanol (1.8 g/kg b.wt.) 1 day per week during the first 6 weeks (Et6) or full 24 weeks (Et24) of gestation. Control macaques were intubated with an isocaloric amount of sucrose water (Ct). The mid-sagittal area of the corpus callosum in 4- to 5-year-old offspring was examined in magnetic resonance (MR) images and in fixed brains. The number of callosal axons was determined by using electron microscopy. In both MR images and fixed brains of macaques treated with ethanol, the corpus callosum was 26% larger than in the controls. The rostral portion was particularly affected by ethanol; it was 55% larger in Et6- and Et24-treated macaques. Axonal size and myelin thickness were unaffected by ethanol, but ethanol-treated macaques had more callosal axons (13.7 x 10(7)) than did controls (9.4 x 10(7) axons). The increase in the rostral corpus callosum suggests that parietal and frontal cortices are particularly susceptible to ethanol. The altered callosal connectivity may be a component of the structural abnormalities that underlie executive processing problems associated with fetal alcohol syndrome.
研究了产前暴露于乙醇对胼胝体轴突数量的影响。怀孕的豚尾猕猴在妊娠的前6周（Et6组）或整个24周（Et24组）期间，每周接受1天乙醇处理（1.8 g/kg体重）。对照猕猴经口插管给予等热量的蔗糖水（Ct组）。在磁共振（MR）图像和固定脑标本中检查4至5岁后代胼胝体的正中矢状面区域。通过电子显微镜确定胼胝体轴突的数量。在接受乙醇处理的猕猴的MR图像和固定脑中，胼胝体均比对照组大26%。胼胝体的喙部受乙醇影响尤为明显；在Et6组和Et24组处理的猕猴中，该部位比对照组大55%。轴突大小和髓鞘厚度不受乙醇影响，但乙醇处理组的猕猴胼胝体轴突（13.7×10⁷）比对照组（9.4×10⁷个轴突）多。胼胝体喙部的增大表明顶叶和额叶皮质对乙醇特别敏感。胼胝体连接性的改变可能是与胎儿酒精综合征相关的执行功能处理问题所基于的结构异常的一个组成部分。
