Variations in the effects of l-methionine- dl-sulfoximine on the activity of cerebral γ-glutamyl transpeptidase in rats as a function of age

Abstract

Changes in the activity of γ-glutamyl transpeptidase (GGTP) and the effects of a subacute dose (150 mg/kg b.wt.) of methionine sulfoximine (MSO) on its activity were studied in cerebral cortex, cerebellum and brainstem of rats of 4 different age groups. GGTP activity increased with increasing age between days 10 and 180 after birth and decreased between 180 and 360 days of age in these 3 regions of the brain. Older animals showed convulsions and succumbed to the toxic effects of MSO. In the younger animals, wobbly gait and splayed leggedness were noticed in the earlier time periods and these animals recovered from the toxic effects of the drug. Following the administration of MSO, GGTP activity was suppressed in all the regions (excepting the cerebral cortex and cerebellum of 90-day-old animals). In 10- and 90-day-old animals, there was a complete recovery of enzyme activity which exceeded the control value as the time progressed. No such recovery was observed in 180- and 360-days-old animals. Parallel changes were observed in the GGTP activity and the behavioural pattern of the animals. These results were discussed in relation to the localization of this enzyme in astrocytes and capillaries.