EFFECT OF GONADECTOMY AND SEX-HORMONES REPLACEMENT ON GLUTATHIONE-RELATED ENZYMES IN RATS

The effects of gonadectomy and sex hormone replacement (either estradi ol (E) or progesterone (P) or both (EP) in females, and testosterone ( T) in males) on plasma and hepatic gamma-glutamyl transpeptidase (PGGT and MGGT respectively), glutathione S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GRx) were investigated. 48 ma le and 72 female rats (120-150g each) were used. The male rats were di vided into 4 groups: control, sham operated, castrated and castrated w ith testosterone replacement at a dose of 4mg kg(-1) body weight. The female rats were divided into 6 groups: control, sham operated and 4 g roups which were gonadectomized, of which three groups received hormon e replacements of estradiol (0.2 mg kg(-1) body weight), progesterone 4 mg kg(-1) body weight) and both estradiol and progesterone together. The animals were sacrificed after two and five months. Higher levels of GPx and GRx activities (p<0.01) were found in female rats whereas G ST were higher in male rats. Although no differences were observed in PGGT activities between male and female rats, MGGT activities were hig her in female rats at five months. Ovariectomy increased PGGT, GST and GRx activities and replacement with either E or P lowered the activit ies. Replacement with EP together brought the levels of plasma GGT, GS T and GRx to that of intact females. Neither gonadectomy nor sex hormo ne replacement influenced hepatic GGT and GPx activities. Castration i ncreased the hepatic GGT and GPx activities of male rats, but reduced the GST levels. Testosterone replacement brought the hepatic GGT and G Px activities to that of intact males. Castration and or testosterone replacement did not influence the levels of plasma GGT and GRx. The re sults suggest that GGT and GSH-related enzymes are subjected to modula tion by male and female sex hormones.