Glutathione turnover in cultured astrocytes: Studies with [15N]glutamate

Marc Yudkoff, David E Pleasure, Lynn Cregar, Zhi Ping Lin, Ilana Nissim, Janet Stern, Itzhak Nissim

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141 Scopus citations

Abstract

The incorporation of [15N]glutamic acid into glutathione was studied in primary cultures of astrocytes. Turnover of the intracellular glutathione pool was rapid, attaining a steady state value of 30.0 atom% excess in 180 min. The intracellular glutathione concentration was high (20-40 nmol/mg protein) and the tripeptide was released rapidly into the incubation medium. Although labeling of glutathione (atom% excess) with [15N]glutamate occurred rapidly, little accumulation of 15N in glutathione was noted during the incubation compared with 15N in aspartate, glutamine, and alanine. Glutathione turnover was stimulated by incubating the astrocytes with diethylmaleate, an electrophile that caused a partial depletion of the glutathione pool(s). Diethylmaleate treatment also was associated with significant reductions of intraastrocytic glutamate, glycine, and cysteine, i.e., the con-stituents of glutathione. Glutathione synthesis could be stimulated by supplementing the steady-state incubation medium with 0.05 mM L-cysteine, such treatment again partially depleting intraastrocytic glutamate and causing significant reductions of 15N labeling of both alanine and glutamine, suggesting that glutamate had been diverted from the synthesis of these amino acids and toward the formation of glutathione. The current study underscores both the intensity of glutathione turnover in astrocytes and the relationship of this turnover to the metabolism of glutamate and other amino acids.

Original languageEnglish (US)
Pages (from-to)137-145
Number of pages9
JournalJournal of Neurochemistry
Volume55
Issue number1
StatePublished - 1990
Externally publishedYes

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Keywords

  • Astrocytes
  • Glutamate
  • Glutathione
  • Mass spectrometry
  • Stable isotopes

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Yudkoff, M., Pleasure, D. E., Cregar, L., Lin, Z. P., Nissim, I., Stern, J., & Nissim, I. (1990). Glutathione turnover in cultured astrocytes: Studies with [15N]glutamate. Journal of Neurochemistry, 55(1), 137-145.