Partially deficient glutamate dehydrogenase activity and attenuated oscillatory potentials in patients with spinocerebellar degeneration

T. Abe, S. I. Ishiguro, H. Saito, M. Kiyosawa, M. Tamai

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32 Citations (Scopus)

Abstract

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 < 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.

Original languageEnglish
Pages (from-to)447-452
Number of pages6
JournalInvestigative Ophthalmology and Visual Science
Volume33
Issue number2
Publication statusPublished - 1992

Keywords

  • glutamate dehydrogenase
  • isoenzyme
  • oscillatory potentials
  • spinocerebellar degeneration

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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