Intracerebroventricular Administration of l ‐Buthionine Sulfoximine: A Method for Depleting Brain Glutathione

Sprague‐Dawley rats (200‐260 g) were anesthetized with chJoral hydrate (400 mg/kg) and polyethylene cannulae were permanently implanted into the lateral ventricles. One or two days later, l ‐buthionine‐[ S,R ]‐sulfoximine (L‐BSO), an apparently selective inhibitor of γ‐glutamylcysteine synthetase, was administered intracerebroventricularly through the cannulae. The brain content of glutathione (GSH) was determined by HPLC with electrochemical detection (gold/ mercury electrode) using N ‐acetylcysteine as internal standard. A time‐course study of the changes in the striatum following a single dose of l ‐BSO (3.2 mg) revealed a maximal depletion of GSH (‐60%) approximately 48 h after the administration. The effects of various doses of l ‐BSO on GSH in the striatum, in the limbic region, and in the cortex were assessed at 24 h and 48 h after the administration. l ‐BSO (0.02‐3.2 mg) produced dose‐dependent reductions of GSH in all brain regions studied at both time intervals. In a long‐term experiment l ‐BSO (3.2 mg) was administered every second day. After 4 days, i.e., after two injections, striatal GSH was reduced by approximately 70%. No further depletion of GSH was obtained by additional injections of l ‐BSO, but GSH was maintained at this low level for the 12 days studied. These results suggest that l ‐BSO, administered intracerebroventricularly, would serve as a useful tool for evaluation of the biological role of GSH in the CNS.