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Hormonal Regulation of Cytochrome P-450-dependent Monooxygenase Activity and Epoxide-metabolizing Enzyme Activities in Testis of Hypophysectomized Rats

Laboratory of Reproductive and Developmental Toxicology [I. P. L., K. S.], and Laboratory of Pharmacology [H. M., J. R. B.], National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709

Since the male gonad is a target organ of both pituitary hormones and androgens, the present study was performed to determine whether testicular aryl hydrocarbon hydroxylase (AHH), epoxide hydrase (EH), and glutathione transferase activities and cytochrome P-450 levels were regulated by folliclestimulating hormone (FSH), luteinizing hormone (LH), and testosterone. Intact, sham-operated controls and hypophysectomized (HYPOX) male rats were used. Forty days after HYPOX, rats received three daily injections of LH, FSH, testosterone, or LH plus FSH (100 µg each), or 0.15 M NaCl. Rats were killed 5, 10, and 15 days after hormone administration. In HYPOX rats, testicular AHH and EH activities and P-450 content were significantly reduced at all time points (20 to 70% of shamoperated control values), but glutathione transferase activity was unchanged. In contrast, testicular AHH, EH, and P-450 were significantly induced in all LH treatment groups but not in FSH or testosterone treatment groups. The highest induction with LH was found in the 15-day treatment group (5- to 14-fold that of 0.15 M NaCl-treated HYPOX control). Since Leydig cells are target cells of LH, the result suggests that LH-stimulated induction of testicular AHH and EH activities and P-450 contents may be primarily associated with the interstitial cell compartment of the testis.

¹ To whom requests for reprints should be addressed, at the Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, P. O. Box 12233, Research Triangle Park, N. C. 27709.

² Present address: Department of Physiology, Nippon Veterinary and Zootechnical College, Tokyo, Japan.

Received 1/11/80. Accepted 4/15/80.

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