Recent evidence has focused attention on the role of oxidative stress in va
rious acute and chronic neurodegenerative diseases. Particularly, a decreas
e in the level of the powerful antioxidant glutathione (GSH) and death of d
opaminergic neurons in substantia nigra are prominent features in Parkinson
's disease. The mode of neuronal death is uncertain; however, apoptosis has
been hypothesized to be mediated through the induction of free radicals vi
a oxidative pathways.
An approach to determine the role of GSH depletion in neurodegeneration and
apoptosis was to create a selective modulation of this antioxidant by meta
bolic manipulations in a clonal cell line of neuronal origin (mouse neurobl
astoma NS20Y). Intracellular GSH levels was lowered by inhibiting its biosy
nthesis with L-buthionine-(S,R)-sulfoximine (BSO), a specific inhibitor of
gamma-glutamylcysteine synthetase. This treatment led to a GSH depletion of
50% after 1 h and 98% after 24 h. A direct cause/effect relationship betwe
en GSH depletion and apoptosis was evidenced in this neuronal cell type. GS
H depletion induced the death of NS20Y and promoted nuclear alterations of
apoptosis as demonstrated by the in situ staining of DNA fragmentation afte
r 5 days of BSO treatment (by terminal-deoxynucleotide transferase-mediated
dUTP-nick end labeling), and the appearance of DNA laddering on agarose ge
l. These results suggested that redox desequilibrium induced by GSH depleti
on may serve as a general trigger for apoptosis in neuronal cells, and are
consistent with the hypothesis that GSH depletion contribute to neuronal de
ath in Parkinson's disease. (C) 1998 Elsevier, Paris.