LOCALIZATION OF 3-BETA-HYDROXYSTEROID DEHYDROGENASE DELTA-5-DELTA-4-ISOMERASE IN RAT GONADS AND ADRENAL-GLANDS BY IMMUNOCYTOCHEMISTRY AND INSITU HYBRIDIZATION

The enzyme complex Δ5-3β-hydroxysteroid dehydrogenase/Δ5-Δ4isomerase (3βHSD) is involved in the biosynthesis of all classes of steroids, namely glucocorticoids, mineralocorticoids, progesterone, and sex steroids. To obtain information on the precise localization of 3βHSD in rat gonads and adrenal glands, two complementary cytochemical techniques were used; immunocytochemical localization was achieved with antibodies developed against purified human placental 3βHSD, while 3βHSD mRNA localization was achieved by in situ hybridization performed with a recently cloned rat 3βHSD cDNA. In the testis, specific immunostaining was restricted to the cytoplasm of the interstitial cells, while by in situ hybridization, specific silver grains were also seen over the interstitial cells. In the ovary, immunostaining was found in the cytoplasm of cells of the corpus luteum and theca interna, while the granulosa cells of the follicles showed no positive reaction. By in situ hybridization, a specific hybridization signal was observed over granulosa cells of the corpus luteum, which are mainly responsible for progesterone secretion, and to a lesser extent over theca interna cells, known for their role in secreting C19androgens. In the adrenals, the three zones of the cortex were equally immunolabeled, whereas no staining could be detected in the medulla. Similarly, by in situ hybridization, silver grains were located over the zona glomerulosa, fasciculata, and reticularis, while no specific autoradiographic reaction could be observed on the chromaffin cells of the medulla. The present study provides new information about the precise cellular localization of 3βHSD in the adrenal glands and gonads in the rat, thus providing useful information about the site of action of 3βHSD, especially in the gonads. Moreover, the approaches used for localization studies, especially quantitative in situ hybridization, should provide a useful tool for assessing the role of hormones on 3βHSD expression in the different compartments of the gonads and adrenal glands. © 1990 by The Endocrine Society.