Steroidogenesis and cell structure: Biochemical pursuit of sites of steroid biosynthesis

Lifetime of microsomal cytochrome P-450 and steroidogenic enzymes in rat testis as influenced by human chorionic gonadotrophin

Submicrosomal distribution of adrenal enzymes and cytochrome P-450 related to corticoidogenesis

Benzo( a )pyrene (BP) metabolism was studied in control and tetrachlorodibenzo- p -dioxin (TCDD)-induced rat testes using the isolated perfusion technique. The testicular artery was perfused with [7,10-14C]BP (specific activity, 60.7 mCi/mmol) dissolved in a Krebs-Ringer bicarbonate buffer fortified with 3% bovine serum albumin (Fraction V) and equilibrated with 95% O2 and 5% CO2 for 20 min at 32°. The BP concentration was 2.8 × 10-7 m, and the rate of perfusion was 20 ml/hr/g testis. BP metabolites were extracted from both the perfusate and the testicular tissue and subjected to high-pressure liquid chromatographic analysis. Comparison of BP metabolites in control and TCDD-induced testes showed that the total amounts of BP metabolites recovered during the 60-min perfusion were 18.3 and 26.2% of total radioactivity, respectively. The pattern of BP metabolites in the control testis demonstrated that the major metabolites in the organic extractable phase were 9,10-dihydroxy-9,10-dihydrobenzo( a )pyrene (52.1%) and 7,8-dihydroxy-7,8-dihydrobenzo( a )pyrene (16.3%). Smaller amounts of 3-hydroxybenzo( a )pyrene (9.2%), quinones (8.6%), and 4,5-dihydroxy-4,5-dihydrobenzo( a )pyrene (4.4%) were also present. This pattern of BP metabolites contrasts with that observed in rat livers or lungs, where phenols and quinones are the primary metabolites. TCDD increased BP metabolism with a concomitant increase in the testicular aryl hydrocarbon hydroxylase activity. The magnitude of various BP metabolites in TCDD-treated rats ranged from 1.5 to 2.8 times control, except 4,5-dihydroxy-4,5-dihydrobenzo( a )pyrene which was not altered by TCDD treatment. Thus, mixedfunction oxidase(s) in rat testis preferentially epoxidate the 9,10 and 7,8 positions of BP. Since 7,8-dihydroxy-7,8-dihydrobenzo( a )pyrene is the precursor of the potent carcinogen, r ,7- t -8-dihydroxy- t -9,10-oxy-7,8,9,10-tetrahydrobenzo( a )pyrene, the TCDD-induced shift in metabolic products could be significant in BP-induced mutagenic and/or carcinogenic effects.

https://cancerres.aacrjournals.org/content/canres/40/9/3297.full.pdf

Metabolism of Benzo(a)pyrene by the Isolated Perfused Rat Testis

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.

https://cancerres.aacrjournals.org/content/canres/40/7/2486.full.pdf

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

Androgen producing activity of a transplanted tumor of mice, originating in the testicular interstitial cell, was biologically confirmed by the fact that the sex-accessory organs of the tumor-bearing mice did not show any decrease in weight even after removal of the testicular glands. After slices of the testicular interstitial cell tumor which had been transplanted to the mice were incubated in vitro with relabeled pregnenolone and progesterone, respectively, as substrate, not only 17α-hydroxyprogesterone, androstenedione and testosterone, but also the corticosteroids such as deoxycorticosterone, 18-hydroxy-ll-deoxycorticosterone, corticosterone and 11-deoxycortisol were isolated as the metabolites and identified, suggesting that this tumor retained enzyme functions of producing adrenocorticoids as well as androgen. Furthermore, progesterone which was administered as a substrate was catabolized into 20α-and 20β-hydroxypregn-4-en-3-one and 6β-hydroxyprogesterone. The enzyme activities related to androgen ...

Steroid biosynthesis in vitro by transplantable interstitial cell tumor of mice. I. Identification and quantitative determination of the metabolites and intracellular distributon of the enzymes related to testosterone formation.

Yoshihiko Tsubura

Papers

Steroid biosynthesis in vitro by transplantable interstitial cell tumor of mice. I. Identification and quantitative determination of the metabolites and intracellular distributon of the enzymes related to testosterone formation.