E. Oconnor et al., BIOSYNTHESIS AND MAINTENANCE OF GSH IN PRIMARY ASTROCYTE CULTURES - ROLE OF L-CYSTINE AND ASCORBATE, Brain research, 680(1-2), 1995, pp. 157-163
We have studied the optimal conditions to maintain the astrocyte GSH l
evels under normal and oxidative stress conditions. The rate of GSH sy
nthesis from L-methionine was statistically lower than from L-cystine
or N-acetyl-cysteine in astrocytes treated with diethyl-maleate, which
is a substrate of GSH S-transferases. This is in accordance with the
fact that cystathionase activity was not detectable. The transport of
L-cystine mediated by the Na+-independent system Xc(-) is the limiting
step in GSH synthesis in astrocytes. Incubation with tert-butyl hydro
peroxide (t-booH) reduced GSH concentration in astrocytes. Thus reduct
ion was ameliorated in part by the addition of ascorbate or dehydroasc
orbate. When L-cystine and ascorbate were added together to the t-booH
-treated astrocytes, the GSH concentration was indistinguishable from
controls. Electron micrographs of astrocytes treated with t-booH showe
d an increased number of vacuoles and mitochondrial swelling. This was
prevented by ascorbate and dehydroascorbate. The physiological implic
ations of the availability of GSH precursors and ascorbate in the main
tenance of GSH in astrocytes are discussed.