大鼠下丘脑酪氨酸羟化酶免疫反应产物的衰老变化

AGING CHANGES IN THE TYROSINE HYDROXYLASE IMMUNOREACTIVITY IN THE RAT HYPOTHALAMUS

本文运用光镜和电镜免疫组化技术,观察了幼年(3月龄)和老年(24月龄)大鼠下丘脑酪氨酸羟化酶(TH)免疫反应产物的衰老变化。与幼年相比,老年TH阳性细胞,尤其是位于下丘脑后部和背内侧核/未定带的阳性细胞,其染色强度明显降低。在数量方面,除视前区外,老年下丘脑的弓状核、室周核、背内侧核/未定带以及下丘脑后部的TH阳性神经细胞呈显著性减少。另外,老年正中隆起的TH阳性神经纤维明显比幼年者减少。电镜下,TH标记的轴突终未呈现退行性改变的迹象。上述衰老变化可能是导致老年下丘脑和垂体内分泌功能紊乱的重要原因。

Aging changes in the tyrosine hydrox lase (TH)immunoreactivity in the hypothalamus were investigatedunder light and electron mieroscopes in young(3--month--old) and old (24-month--old) rats, byusing the avdin--biotin--peroxidase complex (ABC)technique. In 24-month-old rats, the staining intensi-ties of TH--immunoreactive cell were markedly re-duced throughout the hypothalamus, especially in theposterior and dorsomedial/zona incerta tegions, in com-parison with 3--month-old rats. A significant de-crease in numbers of TH---immunoreactive cells wasfound in the arcuate, periventricular, dorsomedial zona incerta and posterior regions with the exception of thepreoptic area in old rats versus young rats. In addi-tion, TH positive nerve fibers in the median eminenceof the old rat were much less than those in the medianeminence of the young rat. In the oldhypothalamus, the degenerative alterations were de-tected under electron microscope in Th--labeledaxonal terminals. The above aging changes are proba-bly important reasons causing the disorders ofhypothalamic and pituitary endoerine functions in thesenescent rat.