Neurochemical analysis on a brain of pure pallidal degeneration with special reference to the termination of GABA ergic pallido-thalamic tract in the thalamus

1)对一例罕见的纯白质变性（PPD）患者的脑区神经递质标志物进行了测定，并与16例对照组进行了比较。γ -氨基丁酸盐（GABA）在丘脑外核（GPe）和内核（GPi）和下丘脑核（ST）中浓度显著降低，谷氨酸盐在GPi和ST中浓度显著升高，丘脑GP、ST、腹前核（VA）和腹外侧核（VL）中胆碱乙酰转移酶（CHAT）活性显著升高。GP组去甲肾上腺素浓度中度降低。多巴胺能和5 -羟色胺能系统在所有检查区域没有显着变化。这些结果表明，神经递质标志物的变化反映了GP神经元及其输出纤维的选择性变性，也反映了GP内纹状突起gaba能纤维和去甲肾上腺素能纤维末端的选择性变性。由于ChAT活性仅在GP及其末端区域增加，因此ChAT活性的增加可能是PPD脑GP神经元损伤的代偿反应。这些神经化学变化是PPD患者特征性运动缓慢的病理生理基础。2)采用显微解剖方法分析PPD和4个对照脑丘脑GABA的精细分布。GABA浓度在PPD脑VL腹口核中特异性降低，说明人类大脑中pallidothalamic纤维含有GABA作为一种神经递质，终止于VL丘脑非常有限的区域。

1) Neurotransmitter markers were measured in brain regions of a very rare case of pure pallidal degeneration (PPD) as compared with 16 controls. Gamma-aminobutylate (GABA) concentration was remarkably decreased in extemal (GPe) and internal (GPi) pallidum (GP) and subthalamic nucleus (ST), glutamate concentration was increased markedly in GPi and ST, and choline acetyltransferase (CHAT) activities in GP, ST, ventroanterior (VA) and ventrolateral (VL) nucleus of the thalamus. Noradrenaline concentration in GP was decreased moderately. Dopaminergic and serotonergic systems showed no remarkable change in all the regions examined. These results suggest that the changes of neurotransmitter markers reflect selective degeneration of GP neurons and their efferent fibers, and also of terminals of striatopallidal GABAergic fibers and probably noradrenergic fibers within GP. Because ChAT activities were increased only in GP and its terminal areas, increase of ChAT activity might be a representation of a compensatory reaction against GP neuronal damage in PPD brain. These sets of neurochemical changes are the pathophysiological basis of the characteristic slow movement in PPD patient. 2) Using microdissection method, fine distribution of GABA in the thalamus was analyzed in PPD and 4 control brains. GABA concentration was specifically decreased in PPD brain in the ventro-oral nucleus of VL, which indicates that pallidothalamic fibers contain GABA as a neurotransmitter in the human brain and terminate in the very restricted area of VL thalamus.