Miki T, Harris S J, Wilce P, Takeuchi Y, Bedi K S
Department of Anatomy, Faculty of Medicine, Kagawa Medical University, Japan.
Hippocampus. 2000;10(3):284-95. doi: 10.1002/1098-1063(2000)10:3<284::AID-HIPO9>3.0.CO;2-K.
We have previously shown that exposing rats to a relatively high dose of ethanol during early postnatal life resulted in a deficit in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rats to ethanol during early postnatal life affected the number of specific neurons in the hippocampus. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 and 15 by placing them for 3 h each day in a chamber containing ethanol vapor. The blood ethanol concentration was about 430 mg/dl at the end of the exposure period. Groups of ethanol-treated (ET) rats, separation controls (SC), and mother-reared controls (MRC) were anesthetized and killed at 16 days of age by perfusion with phosphate-buffered glutaraldehyde (2.5%). The Cavalieri principle was used to determine the volume of various subdivisions of the hippocampal formation (CA1, CA2+CA3, hilus, and granule cell layer), and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There were, on average, about 441,000 granule cells in the granule cell layer and 153,000 to 177,000 pyramidal cells in both the CA1 and CA2+CA3 regions in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This was significantly fewer than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. Thus, neurons in the hilus region may be particularly vulnerable to the effects of a high dose of ethanol exposure during early postnatal life.
我们之前已经表明，在出生后早期将大鼠暴露于相对高剂量的乙醇中会导致空间学习能力出现缺陷。这种能力至少部分受海马结构控制。本研究的目的是确定在出生后早期将大鼠暴露于乙醇中是否会影响海马中特定神经元的数量。通过将Wistar大鼠每天置于含有乙醇蒸气的腔室中3小时，在出生后第10天至15天期间使其暴露于相对高剂量的乙醇中。暴露期结束时血液乙醇浓度约为430mg/dl。在16日龄时，对乙醇处理组（ET）大鼠、分离对照组（SC）和母养对照组（MRC）进行麻醉并通过灌注2.5%的磷酸盐缓冲戊二醛处死。采用 Cavalieri 原理确定海马结构各亚区（CA1、CA2+CA3、齿状回和颗粒细胞层）的体积，并采用物理分割法估计各亚区内神经元的数量密度。通过将数量密度估计值与体积相乘来计算神经元总数。在所有三个处理组中，颗粒细胞层平均约有441,000个颗粒细胞，CA1和CA2+CA3区域平均有153,000至177,000个锥体细胞。在齿状回区域，ET大鼠约有27,000个神经细胞。这明显少于估计在MRC和SC动物中均存在的此类神经元的平均数量38,000个。因此，齿状回区域的神经元可能特别容易受到出生后早期高剂量乙醇暴露的影响。
