Distribution of glutathione S-transferase isoenzymes in human ovary

Abstract

Glutathione S-transferases (GST) are drug-metabolizing and detoxification enzymes involved in the intracellular transport and metabolism of steroid hormones. We studied expression of π, α, μ and microsomal GST by immunohistochemistry in normal human ovaries at different stages of the menstrual cycle and pregnancy and after the menopause. Antibodies were raised in rabbits to purified GST subunits and formalin-fixed, paraffin-embedded sections were studied using the peroxidase-antiperoxidase method. Staining density was graded from very strong to negative. All four isoenzymes were identified in the ovary and their distribution was heterogeneous. The staining pattern of follicles varied with the stage of the menstrual cycle for each isoenzyme. All the ovaries contained abundant GSTπ in stroma. GSTα is closely associated with the glutathione-dependent enzyme δ-5,3-ketosteroid isomerase, which catalyses the conversion of pregnenolone to progesterone and dehydroepiandrosterone to androstenedione. GSTα was localized to the steroid-producing cells and thus may be useful in studying ovaries in conditions where there are assumed alterations in steroid production.