Glutathione-S-transferase in rat ovary: its changes during estrous cycle and increase in its activity by estradiol-17 beta.

Glutathione-S-transferases (GSTs) are drug metabolizing and detoxification enzymes, involved in the intracellular transport and metabolism of steroid hormones. This study indicated that the enzyme was heterogeneously distributed and changed during estrous cycle. The enzyme was found to be predominantly located in the cytosolic fraction while considerable activity was also observed in the mitochondrial and microsomal fractions. The activity of GST was measured during different stages of estrous cycle, viz proestrous, estrous, metestrous and diestrous. The change in its activity was observed during different stages of estrous cycle. Estrous stage was observed to have the highest GST activity. Immature (28-29 days old) rats treated with estradiol-17 beta (5 micrograms in 0.2 ml oil/animal/day, and 10 micrograms in 0.2 ml oil/animal/day, for 3 days), ovarian GST activity seemed to increase significantly (P < 0.01). This increase in the activity and the heterogeneous distribution of GST indicates the functional role of this enzyme in the ovary under endocrine regulation.