兔脑nNOS阳性神经元的形态、结构和分布

Morphology and Distribution of nNOS-Positive Neurons in the Brain of Rabbit

【目的】探讨兔脑神经型一氧化氮合酶(nNOS)阳性神经元的形态、结构和分布。【方法】利用SABC免疫组织化学方法,对各年龄段家兔(仔兔、幼兔、青年兔、成年兔、老年兔)整个脑内nNOS阳性神经元进行观察,用网形和尺形测微尺计数和测量各脑区阳性神经元的密度、胞体直径、第一级突起数及最长突起长度。【结果】(1)家兔的各个脑区均有nNOS阳性神经元和神经纤维出现,其中在大脑皮质、小脑皮质、下丘脑、中脑和脑桥广泛分布,延髓分布极少;(2)nNOS阳性神经元呈深棕色,着色主要在胞质内,细胞核不着色或淡染。神经元胞体形态多种多样,有三角形、圆形、椭圆形、梭形等,神经元突起有一个或者数个。nNOS阳性神经纤维大多呈棕色串珠样,有些区域的阳性纤维相互交织成网状。【结论】nNOS阳性神经元,在仔兔时就已基本发育到成年兔水平,以后随着年龄增长逐渐发育成熟至衰老,到2岁龄(老年兔)时就出现了显著的衰老变化,即密度减小,表达强度减弱,第一级突起数减少,最长突起长度变短等。结果显示:nNOS阳性神经元及其催化产生的NO在家兔中枢神经系统的发育和神经调控中起重要作用。

[ Objective ] The objective was to study the morphology, structure and distribution of nNOS-positive neurons in the rabbit brain. [Method] The study observed the nNOS-positive neurons in the whole brain of rabbits of various ages （the young rabbit, juvenile rabbit, youthful rabbit, grown rabbit, aged rabbit） using SABC immunohistochemistry. Researchers counted and measured the density of the NOS-positive neurons in the areas of the brain, the cell soma diameter, the primary process number and the length of the longest process with reticular and ruler-shaped micrometer. [Result] （1） nNOS-positive neurons and nerve fibers occured in all areas of the rabbit, especially extensively distributed in cerebral cortex, cerebellar cortex, hypothalamus, mesencephalon and pons, while rare in the medulla oblongata. （2） nNOS-positive neurons appeared dark brown, staining mainly in the cytoplasma while nucleus was not stained or even lightly stained. The morphology of the soma of neurons were various shapes, such as triangle, round, elliptic and fusiform. There were one or several processes in the neuron, nNOS-positive nerve fibers mostly were brown and showed likeness to a string of beads. Positive nerve fibers in some areas interlaced into reticular formation. [ Conclusion] nNOS-positive neurons basically developed to the level of the grown rabbits when they were still young rabbits. Later with aging they gradually developed mature until remarkable decrepit changes occured at the age of 2 years （aged rabbit）. That is, the density decreased, the intensity of expression weakened, the number of the primary processes decreaseed, and the length of the longest process shortened. The results showed that nNOS-positive neurons and NO catalyzed to play important roles in the development of the central nervous system and the nerve regulation in the rabbit.