Abe T, Ishiguro S, Saito H, Kiyosawa M, Tamai M
Department of Ophthalmology, Tohoku University School of Medicine, Sendai, Japan.
Invest Ophthalmol Vis Sci. 1992 Feb;33(2):447-52.
Glutamate dehydrogenase (GDH, EC 1.4.1.2) catalyzes the synthesis and degradation of glutamate, an excitatory neurotransmitter in the retina. Recently, two forms of GDH, a soluble heat-stable form and a particulate heat-labile form, have been demonstrated to be deficient in some types of spinocerebellar degeneration (SCD). We measured these forms of GDH activity in leukocyte homogenate from patients with SCD (n = 22) and normal subjects (n = 20) who were examined ophthalmoscopically and electrophysiologically. Seven patients with SCD showed attenuated oscillatory potentials (OPs) on electroretinography. The heat-labile GDH activity in these seven patients (78 +/- 51 nmol/mg protein/h) was significantly lower than that of 15 patients with normal OPs (367 +/- 189) and the normal subjects (397 +/- 1720 (P less than 0.001). Our results indicated that patients with SCD could be separated into two groups electrophysiologically, one with normal OPs and one with attenuated OPs. Also indicated was that a deficiency of heat-labile GDH might affect some functions of neural elements in the retina that are responsible for the generation of OPs.
谷氨酸脱氢酶（GDH，EC 1.4.1.2）催化谷氨酸的合成与降解，谷氨酸是视网膜中的一种兴奋性神经递质。最近，已证实在某些类型的脊髓小脑变性（SCD）中，两种形式的GDH，即可溶性热稳定形式和颗粒性热不稳定形式存在缺陷。我们测量了经眼底镜检查和电生理检查的SCD患者（n = 22）和正常受试者（n = 20）白细胞匀浆中这些形式的GDH活性。七名SCD患者在视网膜电图上显示振荡电位（OPs）减弱。这七名患者的热不稳定GDH活性（78±51 nmol/mg蛋白/小时）显著低于15名OPs正常的患者（367±189）和正常受试者（397±1720，P＜0.001）。我们的结果表明，SCD患者在电生理上可分为两组，一组OPs正常，一组OPs减弱。还表明热不稳定GDH的缺乏可能会影响视网膜中负责产生OPs的神经元件的某些功能。
