Examination of a hypothesis that thining of the cerebral cortex in congenital hydrocephalus is caused by delayd neuronal differentiation

我们研究了先天性脑积水HTX大鼠是否存在神经营养因子的异常表达和神经元分化延迟。于出生后第3天（P3）和第6天（P6）处死HTX大鼠，免疫组化法检测脑组织中神经生长因子（NGF）、脑源性神经营养因子（BDNF）、神经营养因子3（NT-3）及其受体TrkB的定位和表达，并以Wistar大鼠为对照。对照组BDNF在整个大脑皮质呈弥漫性染色，HTX组仅在第2、3层呈强、弱染色。NT-3在对照组的细胞质中呈弥散染色，而在HTX组的细胞核中呈弥散染色。HTX大鼠的这一发现在对照组大鼠的早期就观察到了，这表明HTX大鼠的神经元分化可能延迟。海马：对照组和HTX组大鼠几乎均未检测到NGF的免疫染色，与大脑皮质中的结果相似。两组放射层和定向层均有BDNF表达。对照组神经元的免疫反应性随发育的进行而减弱，而HTX组在P6时仍较强，提示HTX组神经元分化延迟。NT-3免疫组化染色在两组的oriens层，和反应性是相似的。在锥体细胞层，三种神经营养因子在两组间无明显差异，提示先天性脑积水HTX大鼠神经元分化延迟。为了证实这些免疫组化结果，我们现在正在进行定量分析与RT-PCR。

We examined whether aberrant expression of neurotrophic factors and delayd neurinal differentiation occurs in congenital hydrocephalus HTX rats. HTX rats were sacrificed at postnatal day 3 (P3) and day 6 (P6), and immunohistochemical analysis was conducted to see localization and expression of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), and receptor TrkB.Wistar rats were used for controls.The cerebral cortex : NGF were hardly immunostained in both HTX and Wistar rat groups. BDNF were diffusely stained in all the cerebral cortex in controls, while in HTX rats the immunoreactivity was observed only in the 2nd and 3rd layrs where strongly stained and faintly stained cells were intermingled. NT-3 were stained difusely in the cytoplasm of the cell in controls but in the nucleus in HTX rats. This finding in HTX rats was observed in the earlier stage of control rats, suggesting that neuronal differentiation may be delayd in HTX rats. Expression of TrkB were less in HTX rats compared to controls.The hippocampus : Immunostaining of NGF,similar to the finding in the cerebral cortex, was hardly detected in either control or HTX rats. BDNF was stained in the stratum radiatum and the oriens layr in both groups. Its immunoreactivity in controls decreased as the development proceeded, however, in HTX rats was still strong at P6, suggesting the delayd neuronal differentiation in HTX rats. NT-3 was immunostained in the oriens layr, and the reactivity was similar in both groups. In the pyramidal layrs, all the three neurotrophic factors did not show any difference between the two groups.Some results in this study suggest that neuronal differentiation may be delayd in congenital hydrocephalus HTX rats. To confirm those immunohistochemical findings, we are now conducting the quantitative analysis with RT-PCR.