GLUTATHIONE TRANSFERASE ISOENZYME PATTERNS IN THE RAT OVARY

This study was designed to investigate the expression of different iso enzymes of glutathione transferase (GST) in the rat ovary and to follo w possible changes in the pattern of expression during maturation and the different stages of the oestrus cycle. The GST subunits present in the rat ovary (as analyzed by HPLC of affinity-purified GSTs) were A3 , A4, M1, M2, M3 and P1. The most abundant subunit in the ovary was A3 , but the mu enzymes demonstrated the largest increase (3.5-fold) when the mature ovary was compared to the immature organ. An overall decre ase in GST isoenzyme content during dioestrus was observed, but there were no other recurrent changes during the oestrus cycle. Treatment of immature rats with pregnant mare's serum gonadotropin clearly demonst rated that the mu and alpha isoenzymes are up-regulated by gonadotropi n stimulation, i.e. a 4-6 fold increase was seen. This treatment also elevated the P1 subunit 3-fold. At present, it is only possible to spe culate concerning the mechanism(s) underlying these variations in ovar ian GST expression in connection with hormonal changes. The functional significance of these variations is not yet known. (C) 1997 Elsevier Science Ireland Ltd.