大鼠视觉中枢生后发育过程中的一氧化氮合酶阳性神经元的形态及分布变化

THE MORPHOLOGY AND DISTRIBUTION OF NOS POSITIVE NEURONS IN VISUAL CORTEX(AREA 17) AND SUPERIOR COLLICULUS OF RAT IN POSTNATAL DEVELOPMENT

本文用NADPH-黄递酶组织化学技术研究了生后不同年龄段（0、7、14、21、28、35、60、120d）Wistar大鼠视皮层（17区）和上丘表层中一氧化氮合酶阳性神经元的形态及分布的变化。结果表明：视皮层17区中的一氧化氮合酶阳性神经元在生后7d时开始出现，但胞体小，树突分枝少而短，以双极细胞为主，占68.0％;14d时数量达到高峰;且14～21d中，该神经元胞体截面积明显增大，树突分枝复杂化，长度增加，多极细胞占64％;28d后一氧化氮合酶阳性神经元胞体面积，树突分枝长度明显减小，分枝简单化;35d后接近成年动物水平（120d）.生后7d时，一氧化氛合酶阳性神经元主要位于视区的白质和皮层的5、6层中，7d后该神经元及神经纤维在第2／3及4层中明显增多，这种分布状态在35d后趋于稳定。上丘表层中的一氧化氮合酶阳性细胞在生后第2周逐渐出现，第3周迅速增加，第4周达最大值，以后下降并趋于稳定水平。结果提示：大鼠生后发育过程中视觉中枢的一氧化氮合酶阳性神经元数量及形态变化与视觉发育的可塑性有关。

The morphology and distribution of NOS positive neurons in the visual cortex(area 17) and superior colliculus at different postnatal stages of Wistar rat were studied with NADPH-d histochemical technique. The results were as follows: (1) The NOS positive neurons in the area 17 were different in size and shape, The differences were not detectable by postnatal day 0 (D0), but many stained cells could be found by D7 which are mainly bipolar cells (68% in total)with smaller cell bodies and shorter dendrites,The number of NOS positive cells reached a peak by D14. From D14 to D28, the NOS positive neurons acquired larger size and more complex dendrites. They were mainly multipolar cells (64% in total). After D28 the size. the length and complexity of dendrites began to reduce and then maintained at a steady level from D35 to adulthood. During the first postnatal week, NOS positive neurons were mainly distributed in layer 5,6 and white matter of the visual cortex, but they were gradually expanded to layer 2/3,4 after D7. This distribution tended to be unchanged after D35. (2) In superficial superior colliculus there were no detectable NOS activity during the first postnatal week but a few neurons were found by D14. By D21 NOS POsitive neurons were more abundant and their number reached a peak by D28 and then reduced slowly and approached adult level gradually.These results suggest that the morphology and distribution of NOS positive neurons in the rat visual centers are relevant to the visual plasticity during the early postnatal development.