Philbert M A, Beiswanger C M, Manson M M, Green J A, Novak R F, Primiano T, Reuhl K R, Lowndes H E
Department of Pharmacology and Toxicology, College of Pharmacy, Rutgers University, Piscataway, New Jersey 08855-0789, USA.
Neurotoxicology. 1995 Summer;16(2):349-62.
Glutathione and its related enzymes play a major role in the detoxification of toxic chemicals. In rat brain the pattern of distribution of reduced glutathione exhibits cellular heterogeneity, suggesting also the possibility of cellular differences in glutathione conjugating capacity. To understand the potential role of GSH in detoxification of neurotoxicants, the distributions of the glutathione conjugating and metabolizing enzymes, glutathione S-transferase (GST; alpha-, mu- and pi-classes) and gamma-glutamyl transpeptidase (gamma-GT) were determined immunohistochemically in brain, lumbar spinal cord and dorsal root ganglia (DRG) of adult Sprague-Dawley rats using polyclonal antibodies. The influence of tissue fixation on apparent distribution was also examined. Glial cells and neurons throughout the nervous system were only weakly positive with alpha-GST in frozen sections. No immunoreactivity for the alpha-class GSTs was observed in any of the paraformaldehyde-fixed neural specimens examined. In microwave-fixed frozen sections, immunoreactivity to mu-GST was found in astrocytes and neurons throughout the brain and spinal cord, and in the neurons and satellite cells of the DRG. Immunoreactivity for pi-GST was seen in oligodendrocytes but not in astrocytes in any region of the CNS examined. Similarly, satellite cells of the DRG were positive for pi-GST. Neuronal perikarya of the entire neopallium, hippocampus, cerebellum, brainstem, spinal cord and DRG were also positively stained for pi-GST. The differential staining of astrocytes and oligodendrocytes with pi- and mu-GST was unaltered in paraformaldehyde fixed tissues, but the neuronal immunostaining was lost. The ependyma, pia and choroid plexus stained positively with all three GST antibodies regardless of fixation. Gamma-Glutamyl transpeptidase-like immunoreactivity was confined to non-neuronal elements of both central and peripheral nervous systems. Ependymal cells throughout the central nervous systems stained intensely with antibodies directed against gamma-GT. Satellite and Schwann cells of the DRG and glial cells of the spinal cord and brain exhibited moderate to intense immunoreactivity for gamma-GT. The heterogeneous cellular distribution of glutathione and its metabolizing enzymes may reflect cellular differences in capacity for metabolic processing of both endogenous compound and xenobiotics.
谷胱甘肽及其相关酶在有毒化学物质的解毒过程中起主要作用。在大鼠脑中，还原型谷胱甘肽的分布模式呈现出细胞异质性，这也提示了谷胱甘肽结合能力存在细胞差异的可能性。为了解谷胱甘肽（GSH）在神经毒物解毒中的潜在作用，使用多克隆抗体通过免疫组织化学方法测定了成年Sprague-Dawley大鼠脑、腰脊髓和背根神经节（DRG）中谷胱甘肽结合和代谢酶，即谷胱甘肽S-转移酶（GST；α-、μ-和π-类）和γ-谷氨酰转肽酶（γ-GT）的分布。还研究了组织固定对表观分布的影响。在冷冻切片中，整个神经系统的神经胶质细胞和神经元仅对α-GST呈弱阳性。在所检查的任何多聚甲醛固定的神经标本中均未观察到α-类GST的免疫反应性。在微波固定的冷冻切片中，在整个脑和脊髓的星形胶质细胞和神经元以及DRG的神经元和卫星细胞中发现了对μ-GST的免疫反应性。在所检查的中枢神经系统的任何区域，少突胶质细胞中可见对π-GST 的免疫反应性，而星形胶质细胞中未见。同样，DRG的卫星细胞对π-GST呈阳性。整个新皮质、海马、小脑、脑干、脊髓和DRG的神经元胞体也对π-GST呈阳性染色。在多聚甲醛固定的组织中，星形胶质细胞和少突胶质细胞对π-GST和μ-GST的差异染色未改变，但神经元免疫染色消失。无论固定方式如何，室管膜、软脑膜和脉络丛对所有三种GST抗体均呈阳性染色。γ-谷氨酰转肽酶样免疫反应性局限于中枢和外周神经系统的非神经元成分。整个中枢神经系统的室管膜细胞用针对γ-GT的抗体染色强烈。DRG的卫星细胞和雪旺细胞以及脊髓和脑的神经胶质细胞对γ-GT表现出中度至强烈的免疫反应性。谷胱甘肽及其代谢酶的异质细胞分布可能反映了内源性化合物和外源性物质代谢加工能力的细胞差异。
