AGING CHANGES IN ACETYLCHOLINESTERASE POSITIVE NEURONS OF THE GLOBUS PALLIDUS OF THE RAT——A MORPHOMETRIC STUDY / 解剖学报

ABSTRACT

Aging changes in acetylcholinesterase positive (AChE-P) neurons of the globus pallidus were investigated histochemically and morphometrically in young (3 months old) and old (24 months old) Spragur-Dawley male rats. The number of the positive neurons in the old group is decreased by 11.8％ in comparison with the young group. The total process length of the AChE-P neurons in the young rat is approximately 1.4 times as that in the old rat. The length of about 8.6％ of the positive neurons in the old group, however, exceeds the average length of AChE-P cellls in the young group (232.1 ?m). In the old rat, the gray value of AChE-P neurons of the globus pallidus is notably higher than that in the young rat, but the value of nearly 6.8％ of the positive cells in 24-month-old rat is inferior to the average value in 3-month-old rat (117.8). The transverse dimensions of AChE-P cell bodies in the old group are increased by 9.2％ as compared to those in the young group. Morphological observations show that most of AChE-P neurons in the old rat globus pallidus represent a typical degenerative alterations, while a substantial number of the positive neurons in the old animal are characterized by enlarged bodies, strong histochemical reaction as well as dense processes and their branches. The above findings indicate that, in the old rat, a decline of AChE histochemical reactivity and the morphological degeneraton of AChE-P neurons with the advanced age do not occur synchronously in all the AChE-P neurons of the globus pallidus. Therefore, it is suggested that there probably exist a compensative mechanism in senescence of the globus pallidus.