Hormonal regulation of oxidative and reductive activities of 11 beta-hydroxysteroid dehydrogenase in rat Leydig cells

• Published in: Endocrinology (Philadelphia) 1997-01, Vol.138 (1), p.156-161
• Main Authors: Gao, H B, Ge, R S, Lakshmi, V, Marandici, A, Hardy, M P
• Format: Article
• Language: English
• Subjects: 11-beta-Hydroxysteroid Dehydrogenases; 11β-Hydroxysteroid dehydrogenase; Adrenalectomy; Animals; Cell culture; Cells, Cultured; Corticosterone; Culture media; Dehydrogenase; Dehydrogenases; Dexamethasone; Enzymatic activity; Enzymes; Epidermal growth factor; Epidermal Growth Factor - pharmacology; Glucocorticoids; Glucocorticoids - pharmacology; Growth factors; Hepatocytes; Hormones; Hydroxysteroid Dehydrogenases - genetics; Hydroxysteroid Dehydrogenases - metabolism; Hydroxysteroids; Isolation media; Leydig cells; Leydig Cells - enzymology; Liver; Liver - enzymology; Luteinizing hormone; Luteinizing Hormone - pharmacology; Male; Oxidation; Oxidation-Reduction; Rats; Rats, Sprague-Dawley; RNA, Messenger - analysis; Testosterone; Testosterone - pharmacology
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/endo.138.1.4837

We have proposed that the 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) of Leydig cells protects against glucocorticoid-induced inhibition of testosterone (T) production. However, Leydig cells express type I 11 beta-HSD, which has been shown to be reductive in liver parenchymal cells. Because reduction would have the opposite effect of activating glucocorticoid, the present study was designed to determine: 1) whether Leydig cell 11 beta-HSD is primarily oxidative or reductive; and 2) whether oxidative and reductive activities are separately modified by known regulators of Leydig cell steroidogenic function. Leydig cells and liver parenchymal cells were purified from mature male Sprague-Dawley rats (250 g BW), and 11 beta-HSD oxidative and reductive activities were measured using radiolabeled substrates and TLC of triplicate media samples from 1-h incubations immediately after cell isolation. Enzyme activities also were examined in purified Leydig cells at the end of 3 days of culture in vitro in the presence of LH (10 ng/ml), dexamethasone (DEX, 100 nM), T (50 nM), or epidermal growth factor (EGF, 50 ng/ml). In confirmation of previous reports, the reductive activity of 11 beta-HSD was predominant over oxidation in liver parenchymal cells. In contrast, 11 beta-HSD oxidative activity prevailed over reduction in Leydig cells by a ratio of 2:1. The activities of 11 beta-HSD also were analyzed in Leydig cells that were purified 7 days after endogenous glucocorticoid levels were suppressed by adrenalectomy (ADX). Oxidative activity declined in Leydig cells after ADX (22.53 +/- 1.12 pmol/h.10(6) cells, mean +/- SEM vs. 31.47 +/- 1.48 pmol/.10(6) cells in sham-operated controls, P < 0.05), whereas there was no change in reductive activity. This indicated that physiologically active corticosterone is involved in maintaining the predominance of 11 beta-HSD oxidation. When enzyme activities were analyzed in Leydig cells after 3 days of hormonal treatment in vitro, oxidation and reduction were observed to change in opposing directions. Culture of Leydig cells from sham-operated control rats with either LH, T, or EGF resulted in declines in oxidative activity from 33.35 +/- 0.77 to 28.24 +/- 1.93, 27.30 +/- 0.96, and 24.13 +/- 1.02 pmol/ h.10(6) cells (x +/- SE), respectively. However, EGF stimulated 11 beta-HSD reductive activity in cultured Leydig cells from both control (from 18.97 +/- 1.10 to 27.16 +/- 0.71 pmol/h.10(6) cells and ADX rats (from 16.51 +/- 0.75