The intratesticular localization of cytochrome P-450 and cytochrome P-450-dependent enzymes in the rat testis.

Following separation of the seminiferous tubules from the interstitial cells in the rat testis, the amount of cytochrome P-450 and the activities of the cytochrome P-450-dependent enzymes, the 17alpha-hydroxylase and the C17-C20 lyase, were measured in the microsomes of the separated fractions. The amount of cytochrome P-450-dependent enzymes recovered in the microsomal fraction of the interstitial cells ranged from 71 to 86% of the whole testis. However, in some experiments lower recoveries of the activities of the enzymes were attributed to the breakdown of cytochrome P-450 to cytochrome P-420. In all cases, less than 10% of the testicular cytochrome P-450 and the cytochrome P-450-dependent steroidogenic enzymes were found in the tubular microsomes. Moreover, the specific activities of the 17 alpha-hydroxylase and the C17-C20 lyase were found to be 10 to 30 times higher in the interstitial tissue than in the seminiferous tubules of the rat testis. From these results, we have concluded that cytochrome P-450 and the activities of the cytochrome P-450-dependent enzymes in the rat testis are predominantly, if not sole, located in the interstitial cells.

SC 25152: A potent mineralocorticoid antagonist with reduced affinity for the 5 alpha-dihydrotestosterone receptor of human and rat prostate.

It has previously been shown that spironolactone possesses antiandrogenic activity in the rat and interacts with rat prostate 5 alpha-dihydrotestosterone cytoplasmic receptors to block the nuclear uptake of this hormone. Current evidence suggests that this androgen receptor interaction may be an important mechanism through which spironolactone causes endocrine side effects in rat and man. We have analyzed the interactions of several spirolactone analogs with the androgen receptor of human and rat prostate and the mineralocorticoid receptor of human and rat kidney. One analog, SC 25152, was found to have considerably reduced affinity for the prostate 5 alpha-dihydrotestosterone receptor [Ka = 24 +/- 1% and 19 +/- 6% (mean +/- SE) in the human and rat, respectively, of the Ka for spironolactone] while maintaining similar affinity for the mineralocorticoid receptors of human and rat kidney [Ka = 113 +/- 37% and 86 +/- 7% (mean +/- SE), respectively, of the Ka for spironolactone]. These findings would predict this analog to have reduced antiandrogenicity at equivalent therapeutic doses.

Effect of spironolactone on sex hormones in man.

Administration spironolactone at a dosage of 400 mg/day to healthy male volunteers for 5 days resulted in a significant rise in plasma progesterone and 17alpha-hydroxyprogesterone which persisted throughout the study. A transient increase in plasma FSH and LH concentration was observed after the second but not the third or fifth days of drug administration. There was no change in plasma concentration of testosterone, 17beta-estradiol, or prolactin. These findings are consistent with a previously-reported spironolactone-induced destruction of the microsomal enzyme cytochrome P-450, an enzyme necessary for 17-hydroxylase and desmolase activity. The results do not explain the decrease of libido, the impotence, and the gynecomastia frequently associated with spironolactone therapy in males.

The effect of the administration of spironolactone on the concentration of plasma testosterone, estradiol and cortisol in male dogs (1).

The effect of the administration of spironolactone, deacetylspironolactone, aldadiene or soldactone on the concentration of plasma testosterone, estradiol, and cortisol was examined in male dogs. Decreases of 60 to 75% in plasma testosterone and estrodiol occur only at high doses (100 mg/kg) of spironolactone or deacetylspironolactone but not at low doses of spironolactone (5 to 10 mg/kg); they occur concomitantly with similar decreases of androgen formation by the testis. No decreases were detected with aldadiene or soldactone. Treatment of dogs with spironolactone (100 mg/kg) also lowered by 50 to 65% the concentration of cortisol in adrenal venous plasma.

Carbon-13 nuclear magnetic resonance studies of spironolactone and several related steroids.

The 13C chemical shifts for all the carbon atoms is spironolactone have been assigned. Assignments for nine additional steroids which include the C-7 beta isomer of spironolactone, its C-7 thiol hydrolysis product, the 7 alpha-thioacetate derivative of testosterone and its thiol hydrolysis product are also reported.