Spironolactone and cytochrome P-450: impairment of steroid 21-hydroxylation in the adrenal cortex

Spironolactone and XPB: An Old Drug with a New Molecular Target

Spironolactone (SP) is commonly used for the treatment of heart failure, hypertension, and complications of cirrhosis by antagonizing the mineralocorticoid receptor. However, SP also antagonizes the androgen receptor, and thus SP has also been shown to be effective in the treatment of acne, hair loss, and hirsutism in women. Interestingly, recent drug repurposing screens have identified new and diverse functions for SP as a simulator of tumor immunosurveillance and as an inhibitor of DNA repair and viral infection. These novel pharmacological effects of SP have all been linked to the ability of SP to induce the rapid proteolytic degradation of the xeroderma pigmentosum group B (XPB) protein. XPB is a critical enzymatic component of the multi-subunit complex known as transcription factor II-H (TFIIH), which plays essential roles in both DNA repair and the initiation of transcription. Given the critical functions for XPB and TFIIH in these processes, the loss of XPB by SP could lead to mutagenesis. However, the ability of SP to promote cancer stem cell death and facilitate immune recognition may counteract the negative consequences of SP to mitigate carcinogenic risk. Thus, SP appears to have new and interesting pharmacological effects that may extend its potential uses.

Contrasting effects of eplerenone and spironolactone on adrenal cell steroidogenesis

Spironolactone and eplerenone are widely used as mineralocorticoid antagonists. Spironolactone has several nonspecific actions including inhibition of androgen receptor and steroid hormone biosynthesis. While studies have shown that eplerenone does not exhibit nonspecific actions on androgen receptor, its effects on steroid hormone production have not been reported. Herein, the effects of eplerenone (0.1-30 microM) and spironolactone (0.1-30 microM) on steroid production were examined in human adrenocortical H295R cells. Spironolactone inhibited basal production of cortisol (91%) and aldosterone (53%). Treatment of H295R cells with angiotensin II (Ang II) for 24 h increased aldosterone production by 11-fold. Spironolactone inhibited Ang II stimulation of aldosterone production by 80%. Addition of pregnenolone increased aldosterone (9-fold) and cortisol (3-fold) production. Spironolactone inhibited pregnenolone metabolism to aldosterone (67%) and cortisol (74%). The inhibitory effects of spironolactone occurred at concentrations far higher than those needed to block mineralocorticoid receptor, suggesting an action directly on the enzymes involved in steroid production. In contrast, eplerenone did not inhibit basal, Ang II, forskolin, pregnenolone-stimulated cortisol, or aldosterone production. Together, these data demonstrate that opposed to spironolactone, pharmacologic concentrations of eplerenone do not inhibit adrenal cell aldosterone or cortisol production.

Spironolactone directly inhibits proliferation of cultured human facial sebocytes and acts antagonistically to testosterone and 5 alpha-dihydrotestosterone in vitro

Spironolactone produces antiacne effects and has recently been shown to inhibit 5 alpha-dihydrotestosterone (5 alpha-DHT) receptors in human sebaceous glands. We applied spironolactone alone and combined with testosterone and 5 alpha-DHT to investigate its effects on the proliferation of human sebocyte cultures derived from facial skin. Secondary human facial sebocytes in 96-well culture plates were treated for 10 d by a single or combined application of testosterone (10(-8)-10(-5) M), 5 alpha-DHT (10(-8)-10(-5) M), and spironolactone (10(-12)-10(-7) M) in serum-free basal medium. Cell proliferation was assessed in six wells using a fluorometric assay. Testosterone and 5 alpha-DHT significantly stimulated sebocyte proliferation in a dose-dependent manner, the effect being strongest with 5 alpha-DHT. Spironolactone, on the other hand, caused a dose-dependent inhibition (25% and 50% at 10(-9) and 10(-7) M, respectively). Combined treatment of human facial sebocytes with spironolactone and testosterone or 5 alpha-DHT resulted in a lower proliferation than with androgens alone. The fact that spironolactone directly and dose dependently inhibits the proliferation of cultured human facial sebocytes and acts antagonistically to testosterone and 5 alpha-DHT at the cellular level is indicative of a receptor-mediated effect.

Destruction of testicular cytochrome P-450 by 7 alpha-thiospironolactone is catalyzed by the 17 alpha-hydroxylase

Studies were done to determine the role of the 17 alpha-hydroxylase in the conversion of 7 alpha-thiospironolactone (7 alpha-thio-SL) to a reactive metabolite causing the degradation of testicular cytochrome P-450. Incubation of guinea pig testicular microsomes with 7 alpha-thio-SL plus NADPH resulted in an approx. 70% decline in cytochrome P-450 content and even greater loss of 17 alpha-hydroxylase activity. Addition of the 17 alpha-hydroxylase inhibitor, SU-10'603, to the incubation medium prevented the degradation of P-450 by 7 alpha-thio-SL. Similarly, preincubation of testicular microsomes with anti-P-45017 alpha,lyase IgG to inhibit 17 alpha-hydroxylation, diminished the subsequent loss of P-450 caused by 7 alpha-thio-SL. The results indicate that the 17 alpha-hydroxylase catalyzes the conversion of 7 alpha-thio-SL to the reactive metabolite responsible for P-450 destruction. The accompanying loss of 17 alpha-hydroxylase activity supports the hypothesis that suicide inhibition is the mechanism involved.

Mechanism of action of spironolactone on cortisol production by guinea pig adrenocortical cells

Studies were done to determine the mechanism(s) of action of spironolactone (SL) and of its deacetylated metabolite, 7 alpha-thio-SL, to inhibit cortisol secretion by guinea pig adrenocortical cells in vitro. Preincubation of cells at 37 degrees C with SL or with 7 alpha-thio-SL caused a time-dependent decline in subsequent ACTH-stimulated cortisol secretion. In the absence of a preincubation, neither compound affected cortisol production, indicating the need for production of an active metabolite. When the 17 alpha-hydroxylase inhibitor, SU-10'603, was included during the preincubation period, neither SL nor 7 alpha-thio-SL decreased cortisol secretion, indicating the involvement of the 17 alpha-hydroxylase in the activation of both compounds. By contrast, neither the 11 beta-hydroxylase inhibitor, metyrapone, nor the cholesterol sidechain cleavage inhibitor, aminoglutethimide, diminished the effects of SL or of 7 alpha-thio-SL on cortisol secretion. Preincubation of cells with SL or 7 alpha-thio-SL also decreased the conversion of exogenous progesterone to cortisol, but did not affect cortisol production from the 17 alpha-hydroxylated substrates, 17 alpha-hydroxyprogesterone and 11-deoxycortisol, suggesting that only 17 alpha-hydroxylation was impaired. In addition, there was a decline in 17 alpha-hydroxylase activity in microsomes isolated from cells preincubated with SL or with 7 alpha-thio-SL, but no change in microsomal 21-hydroxylase or in mitochondrial 11 beta-hydroxylase and cholesterol sidechain cleavage activities. The results indicate that the direct effects of SL and of 7 alpha-thio-SL on the adrenal cortex to decrease cortisol production result from the selective inhibition of 17 alpha-hydroxylation. Since 17 alpha-hydroxylase activity is apparently required for the activation of both compounds, suicide inhibition of the enzyme may be the mechanism of action.

Spironolactone in dermatologic therapy

In the treatment of androgen-mediated skin disorders spironolactone provides a valuable therapeutic option. This article reviews the use of spironolactone as an antiandrogen in dermatologic therapy. The endocrinologic effects, pharmacology, dermatologic uses, and side effects are discussed, and guidelines for its use are provided.

Treatment of hirsutism with the pure antiandrogen flutamide

The effectiveness of the antiandrogen flutamide in combination with an oral contraceptive was studied in 20 patients with moderate to severe hirsutism. Eight patients had no previous therapy, whereas 12 had failed to respond to oral contraceptives, spironolactone, or dexamethasone therapy. Treatment with the antiandrogen flutamide (250 mg twice daily) and an oral contraceptive (Ortho 1/35) resulted in a particularly rapid and marked decrease in the total hirsutism score, which reached the normal range at 7 months. Seborrhea, acne, and hair loss score were also rapidly corrected. Treatment was associated with a decrease in plasma luteinizing hormone, progesterone, and estradiol levels. Plasma sex hormone-binding globulin levels were initially low in 18 to 20 patients but increased significantly during therapy. No clinically significant side effects were observed.

Inhibition of hormonal-induced cAMP and steroid production by inhibitors of pregnenolone metabolism in adrenal and Leydig cells

The effects of inhibitors of pregnenolone metabolism, WIN-24540 and spironolactone, on adrenocorticotropic hormone (ACTH)- and human chorionic gonadotropin (hCG)-induced cAMP and steroid production by bovine (BAC) and ovine (OAC) adrenal cells and pig Leydig cells (PLC) were investigated. The inhibitors reduced cAMP production by adrenal and Leydig cells by about 75% and 60%, respectively (P less than 0.001). Further, the inhibitors also reduced the cholera toxin- and forskolin-induced cAMP production by pig Leydig cells. In the presence of the inhibitors, corticosterone and testosterone production by BAC and PLC, respectively, following hormonal stimulation was reduced by more than 90%. However, pregnenolone production by BAC and PLC under these conditions represented only 12% and 42% of the corticosterone and testosterone production, respectively, in the absence of inhibitors. Moreover, the inhibitors also reduced the steroidogenic response of PLC to 8-Br-cAMP and the conversion of 22(R)-hydroxycholesterol to pregnenolone by BAC and PLC. The reduced production of pregnenolone in the presence of inhibitors was in part due to the weak inhibition of 17 alpha-hydroxylase by spironolactone. However, when OAC cells were incubated in the presence of WIN-24540 and SU-10603, a potent 17 alpha-hydroxylase inhibitor, the amount of pregnenolone produced in response to ACTH or 22(R)-hydroxycholesterol was only 10% and 19%, respectively, of the steroids (corticosterone plus cortisol) secreted in the absence of inhibitors. The results show that the inhibitors of pregnenolone metabolism reduced, in both adrenal and Leydig cells, the response of adenylate cyclase to several effectors and the activity of the cholesterol side-chain cleavage.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-androgens in gynaecological practice

Hirsutism and acne in women are common distressing problems. Unwanted hair growth, acne and seborrhoea result from the action of androgens on the skin. Such effects depend not only on increased androgen production by the ovary or adrenal gland but also on the bioavailability of androgen to peripheral tissues. This in turn is related to transport of androgens in plasma by specific binding proteins and to peripheral metabolism of testosterone and androstenedione to their more potent 5 alpha-reduced derivatives. An effective anti-androgen is one which blocks the androgen receptor-mediated actions of testosterone and DHT on skin. CPA, the treatment of choice in the UK, is a potent androgen receptor-blocking steroid which also has progestational properties. When combined with ethinyloestradiol it also suppresses ovarian function, thus reducing androgen production, and provides effective contraception.

Adrenal mitochondrial metabolism of spironolactone. Absence of metabolic activation

Previous investigations have established that spironolactone (SL) administration to guinea pigs decreases adrenal mitochondrial and microsomal cytochrome P-450 content, and that the latter requires microsomal activation of the drug. Studies were carried out to determine if adrenal mitochondrial metabolism (activation) of SL was similarly involved in the effects of the drug on mitochondrial cytochrome P-450 destruction. Incubation of guinea pig adrenal mitochondria with SL in the absence of NADPH resulted in the formation of 7 alpha-thio-SL as the only metabolite. In the presence of an NADPH-generating system, an unknown polar metabolite was also produced. The mass spectrum of the unknown compound suggested that it was a hydroxylated derivative of SL. Incubation of mitochondrial preparations with 7 alpha-thio-SL also resulted in the formation of a polar metabolite, but the latter had a different HPLC retention time than that of the SL metabolite. Formation of the polar SL metabolite was prevented by metyrapone, an 11 beta-hydroxylase inhibitor, and was greatest in mitochondria from the adrenal zone having the highest 11 beta-hydroxylase activity. Steroid substrates for 11 beta-hydroxylation inhibited the production of the SL metabolite. Mitochondrial incubations with SL or with 7 alpha-thio-SL in the presence or absence of an NADPH-generating system did not affect cytochrome P-450 concentrations. The results indicate that, unlike the microsomal effects of SL, local activation of SL is not responsible for the destruction of adrenal mitochondrial cytochromes P-450. The major adrenal mitochondrial metabolites of SL appear to be 11 beta-hydroxy-SL and 7 alpha-thio-SL.

A comparative study of Aldactone and Diane in the treatment of hirsutism

A comparative study has been performed in order to evaluate the relative potency of Diane and Aldactone in reducing hair growth as well as the effect on blood hormone concentrations. Thirty-six women participated in the study and depending on the desire for contraception, 22 were treated with Diane and 14 with Aldactone. The results show that Aldactone (50 mg per day) had little effect on hormone concentrations, only LH was significantly reduced after 12 months of treatment. Despite the lack of effect on hormone levels, all 14 women reported reduced hair growth and after 5 months of treatment, 58% also reported a decrease in the formation in new hair growth. In contrast to the Aldactone treated group, the women on Diane medication demonstrated a marked decrease in circulating hormone levels with a subsequent effect on the hair parameters. The clinical effects were, however, not quite of the same degree as those seen with Aldactone treatment. Approximately 20% exhibited no response for any of the 3 hair-parameters (reduced hair growth, formation of new hair and a change to softer hair). The response time before any effect was observed was also longer than that seen with the Aldactone group. The data suggest that, at the dosages employed, Aldactone has a better clinical effect on the hair parameters despite a lack of effect on circulating hormone levels. One should, however, be aware that Diane contains only 2 mg cyproterone acetate (CPA) and a better effect would most probably have been obtained using a higher dosage of CPA.

The endocrine effects of spironolactone used as an antiandrogen

Eight castrate, estrogen-replaced women were given 200 mg spironolactone daily for 4 weeks. The response of plasma dehydroepiandrosterone sulfate (DHEAS), testosterone (T), and androstenedione (delta 4A), all indicators of adrenal C19-steroid production, varied greatly among individuals. Sixteen women with idiopathic hirsutism were given night-time dexamethasone (DEX) and then superimposed spironolactone for 4 weeks, followed by DEX without spironolactone for an additional 4 weeks. As expected, DHEAS, T, and delta 4A declined on DEX treatment. On addition of spironolactone, there was little further change in DHEAS, while plasma T declined in 7 of 16 women, including all those whose T level had remained elevated despite DEX treatment; most values rebounded when spironolactone was discontinued. The authors conclude from intact DEX-suppressed women that ovarian T, especially when increased, is frequently lowered by spironolactone. Thus, both adrenal and ovarian androgen production (as measured by prevailing plasma levels) may be diminished by this agent. These highly variable effects on androgen production are unlikely to account for the consistent antiandrogenic effects reported clinically.

New evidence for a direct effect of prolactin on rat adrenal steroidogenesis

The direct effect of prolactin on rat adrenal steroidogenic enzyme activity was evaluated by measuring plasma and adrenal cytosol steroid levels and adrenal microsomal 3B-hydroxysteroid dehydrogenase/isomerase (3B-HSD), 21 hydroxylase (21-OHase) and mitochondrial 11-hydroxylase (11-OHase) after in vivo administration of purified rat prolactin (rPRL) to adult, female Sprague-Dawley rats. Animals were ovariectomized, hypophysectomized and replaced with ACTH. Two days after surgery rPRL was administered i.p. at doses of 1.0, 10.0 and 100.0 micrograms (micrograms) every 4 hours for 5 days to experimental animals. Control rats received vehicle injections. All rats were sacrificed by decapitation and blood and adrenal glands collected. The adrenals were pooled into each rPRL dose group and mitochondria, microsomes and cytosol prepared from each pool. The activities of 3B-HSD, 21-OHase and 11-OHase were measured using as substrates 14C-dehydroepiandrosterone, 14C-progesterone and 14C-deoxycorticosterone, respectively. Plasma prolactin levels rose from 9.9 +/- 2.5 ng/ml in the control animals to 166.0 +/- 37.7 ng/ml (p less than 0.001) in the 100 micrograms rPRL dose group. Plasma corticosterone levels were not statistically different in the experimental groups when compared to controls. However, adrenal weight was increased in the high dose rPRL group (34.9 +/- 0.9 mg vs 41.9 +/- 1.2 mg, p less than 0.025). Hyperprolactinemia did not influence microsomal 3B-HSD or mitochondrial 11-OHase activities but was associated with a dose dependent decrease in microsomal 21-OHase activity when compared to controls (p less than 0.001). Adrenal cytosol progesterone levels increased with increasing rPRL dose consistent with a 21-OHase block during hyperprolactinemia. These data suggest that prolactin has a direct effect on rat adrenal 21-OHase in vivo.

The effect of spironolactone on genital skin 5 alpha-reductase activity

The effect of spironolactone (S) on genital skin 5 alpha-reductase activity (5 alpha-RA) of hirsute women (HW) in vivo as well as in normal genital skin in vitro was evaluated. Thirteen HW (Ferriman-Gallwey score of 23.3 +/- 2.8) received S 100 mg twice a day for a month. Twenty-three non-hirsute women were selected as controls for the assessment of genital skin 5 alpha-RA. S was added to incubations of genital skin from 9 additional controls in vitro in concentrations from 1.2 X 10(-8) to 10(-5) M. HW had significantly higher conversion ratios (CR) of T to DHT compared to controls (P less than 0.05). Post treatment values for the CR T to DHT were significantly lower than prior to S (17.5 +/- 1.7 and 8.05 +/- 1.2%, P less than 0.05) and the mass of DHT produced also decreased by 37 +/- 9% (P less than 0.05). The CR T to 3 alpha-diol decreased by 30 +/- 9% (P less than 0.05). In 11 of 13 women, a significant reduction of 5 alpha-RA was demonstrated while in 2 patients the activity remained unchanged. The maximum in vitro inhibitory effect of S on the CR T to DHT occurred with a concentration of 1.2 X 10(-5) M (P less than 0.01). In conclusion, S has a direct inhibitory effect on 5 alpha-RA. The beneficial effect of S treatment in HW may be related, in part, to this inhibition of 5 alpha-RA.

Effects of ketoconazole on rat testicular steroidogenic enzymatic activities

Ketoconazole (K) is an antifungal imidazole derivative which has been shown to be a potent inhibitor of testosterone (T) biosynthesis in rodents and humans. To study the effect of K on rat testicular steroidogenesis we measured the activities of five testicular microsomal steroidogenic enzymes in K-treated rats and controls. Thirty male adult rats were given either 2 mg K or water every 12 hours by mouth during 5 days. Mean testicular weight was similar in both groups of animals. The K-treated group had a T serum concentration of 83 +/- 14 ng/dL whereas it was 94 +/- 16 ng/dL in the control group (NS). The K-treated animals had decreased activities of the 3 beta-hydroxysteroid dehydrogenase (830 +/- 48 vs 2,245 +/- 109 pmol/mg protein/min, P less than 0.001), 17-hydroxylase (243 +/- 5 vs 676 +/- 17 pmol/mg protein/min, P less than 0.001), 17-ketosteroid reductase (31 +/- 2 vs 169 +/- 7 pmol/mg protein/min, P less than 0.001), and aromatase enzymes (92 +/- 6 vs 123 +/- 7 pmol/mg protein/min, P less than 0.01). The 17,20-desmolase activity was similar in both groups of animals (210 +/- 4 vs 171 +/- 18 pmol/mg protein/min). We conclude that K given orally to rats inhibits the activity of several testicular steroidogenic enzymes.

Effect of spironolactone on electrolytes, renin, ACTH and corticosteroids in the rat

Spironolactone (S), known to act as a mineralocorticoid antagonist, has been shown in some circumstances to inhibit steroid biosynthesis. To investigate these two actions in vivo in the rat, animals fed a normal or low Na+ diet were treated with S for 7 days. In animals fed a normal Na+ diet, urinary and faecal electrolytes, aldosterone and corticosterone excretion were measured daily, plasma renin, aldosterone, corticosterone, ACTH, progesterone, DOC and 18-OH-DOC were determined after 4 and 7 days of treatment. In animals fed a low Na+ diet, urinary electrolytes were measured daily and plasma and urinary aldosterone and corticosterone were determined at intervals during the introduction of the diet and in the course of treatment. On a normal Na+ diet, S induced a slight non significant rise in the urinary Na+/K+ ratio on the first day of treatment, no change in faecal electrolyte excretion, and a sustained increase in aldosterone but not in corticosterone excretion. It produced a 6-fold elevation in plasma aldosterone levels, a less marked rise in renin and progesterone, a delayed increase in DOC and no change in ACTH, 18-OH-DOC or corticosterone concentration. On a low Na+ diet, treatment induced a rise in the urinary Na+/K+ ratio, and in urine and plasma aldosterone levels and no change in corticosterone values. Our results confirm, in the intact rat, the antimineralocorticoid action of S characterized by an increase in Na+ excretion but no change in K+ elimination. No inhibitory effect of spironolactone on aldosterone, corticosterone or 18-OH-DOC biosynthesis could be demonstrated in our experimental model.

The effects of prolactin on rat ovarian function

Hyperprolactinemia has been associated with several reproductive disorders. To investigate whether hyperprolactinemia directly affects rat ovarian function, we examined the ovarian histopathology and the activities of the four ovarian enzymes 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 17-hydroxylase (17-OH), 17,20-desmolase (17,20-D) and aromatase in hyperprolactinemic rats and controls. Hypophysectomized, gonadotropin-treated Fisher rats were made hyperprolactinemic by isografting pituitary glands under the kidney capsule. The control animals received skeletal muscle. The ovaries were resected, pooled according to prolactin levels and microsomal enzyme activities were measured from each pool. Prolactin (PRL) levels were 344 +/- 23 ng/ml in the hyperprolactinemic rats and 18 +/- 5 ng/ml in the controls (p less than 0.001). Estradiol concentrations were 609 +/- 47 pg/ml in the hyperprolactinemic animals and 56 +/- 13 pg/ml in the controls (p less than 0.001). Ovarian and uterine weights were significantly higher in the hyperprolactinemic rats (p less than 0.02). Ovarian histopathology demonstrated benign polycystic transformation in the hyperprolactinemic animals. Hyperprolactinemia had no effect on 3 beta-HSD, but was associated with significant decreases in the 17-OH, 17,20-D and aromatase activities when compared to controls (p less than 0.001). We conclude that prolactin has a direct effect on rat ovarian function which appears to be independent of changes in gonadotropin secretion.

The effects of temperature on the activity of testicular steroidogenic enzymes

Decreased sperm counts and impaired sperm motility are present in a substantial proportion of men with varicocele. Elevations in the temperature of the affected testis, and increased spermatic vein estradiol (E2) concentrations have been found in some of these patients. To investigate the possibility that increases in temperature lead to a pattern of testicular steroidogenesis that results in increased E2 synthesis, we have examined the effects of temperature changes on the activities of four important testicular steroidogenic enzymes. 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 17-hydroxylase (17-OH), 17,20-desmolase (17,20-D) and aromatase activities were measured in the microsomal fraction of rat, pig and horse testes. Incubations were performed at 34 degrees C, 36 degrees C, and 38 degrees C. The activities of all 4 enzymes increased with each 2 degrees C temperature elevation in roughly proportional amounts. We conclude that minor elevations in incubation temperature are associated with increases in the in vitro activity of four key testicular steroidogenic enzymes.

Direct effect of the luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH on rat testicular steroidogenesis

The luteinizing hormone releasing hormone analog D-Trp6-Pro9-Net-LHRH (LHRHa) inhibits rat testicular testosterone secretion. To determine whether LHRHa decreases serum testosterone concentrations solely by inhibiting gonadotropin secretion or, in addition, by influencing directly testicular testosterone biosynthesis, we examined the effects of LHRHa on the activities of 5 key testicular steroidogenic enzymes. Thirty hypophysectomized, hOG treated rats were given either LHRHa (1 micrograms sc/day) or saline during 7 days. The LHRHa treated animals exhibited a significant decrease of serum testosterone when compared to the control group (498 +/- 37 ng/dl vs 2044 +/- 105 ng/dl, mean +/- SEM, P less than 0.001). 17-Hydroxyprogesterone serum levels were also decreased in the LHRHa treated rats (61 +/- 6 ng/dl vs 93 +/- 7 ng/dl, P less than 0.005), while serum progesterone levels were similar in both groups of animals. These changes in steroid concentrations were associated with decreases in the microsomal enzyme activities of 17-hydroxylase (37 +/- 9 vs 654 +/- 41 pmol/mg protein/min, P less than 0.001), 17,20-desmolase (103 +/- 9 vs 522 +/- 47 pmol/mg protein/min, P less than 0.001), 3 beta-hydroxysteroid dehydrogenase (1.7 +/- 0.02 vs 4.1 +/- 0.1 nmol/mg protein/min, P less than 0.001), aromatase (95 +/- 7 vs 228 +/- 6 pmol/mg protein/min, P less than 0.001) and 17-ketosteroid reductase (167 +/- 9 vs 290 +/- 18 pmol/mg protein/min, P less than 0.01) in the LHRHa treated animals. These findings indicate that LHRHa can inhibit directly rat testicular testosterone biosynthesis.

Spironolactone- and canrenone-induced changes in hepatic (Na+,K+)ATPase activity, surface membrane cholesterol and phospholipid, and fluorescence polarization in the rat

We studied changes in hepatic membrane (Na+,K+)ATPase activity and membrane lipids induced by canrenoate, the water-soluble congener of canrenone, the active metabolite of spironolactone. (Na+,K+)ATPase activity was decreased after canrenoate in a dose- and time-dependent manner. Decreased activity was demonstrated at the lowest dose (91% of control after 5 mumoles per 100 gm body weight per day X 3 days); the maximum dose (30 mumoles per 100 gm body weight per day X 3 days) resulted in activity 38% of untreated control values. A 20 mumoles per 100 gm body weight per day dose decreased enzyme activity to 89 and 55% of control after 24 and 72 hr, respectively. The nonionic detergent Triton WR-1339 partially reversed drug-induced inhibition, suggesting that the enzyme changes may be related to altered membrane lipids. Membrane cholesterol increased 17% after 3 days of 30 mumoles canrenoate per 100 gm body weight per day; phospholipids decreased by 12%. The cholesterol to phospholipid molar ratio increased from 0.419 to 0.555. Membrane fluidity, as measured by the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene decreased after treatment with 20 mumoles canrenoate per 100 gm body weight per day for 3 days. These results describe in vivo and in vitro inhibition of hepatic (Na+,K+)ATPase activity. Increased membrane cholesterol with decreased phospholipid alters membrane fluidity and may be partially responsible for the change in (Na+,K+)ATPase activity.

The effects of estradiol and progesterone on rat ovarian 17-hydroxylase and 3 beta-hydroxysteroid dehydrogenase activities

Testosterone biosynthesis by Leydig cells can be modulated by estradiol. This modulation appears to occur at the 17-hydroxylase and 17,20-desmolase stage. In this study we have examined the effects of estradiol and progesterone on the activities of the 17-hydroxylase (17-OH) and 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in rat ovarian tissue, to examine the hypothesis that estradiol may regulate these enzymes in the ovary as well as in the testis. Estradiol capsule implants produced a decrease in 17-OH activity (0.5 +/- 0.05 vs. 2.1 +/- 0.1 nmol/mg protein/min, mean +/- SEM, p less than 0.001), and an increase in 3 beta-HSD activity (15.5 +/- 0.9 vs 9.7 +/- 0.7 nmol/mg protein/min p less than 0.001). Progesterone injections produced a decrease in both 17-OH (0.9 +/- 0.1 vs. 2.3 +/- 0.2 p less than 0.005) and 3 beta-HSD (2.5 +/- .4 vs. 8.6 +/- 0.5; p less than 0.005) activities. We conclude that estradiol decreases 17-OH activity in the ovary as it does in the testis. This, coupled with an increase in 3 beta-HSD may explain the pre-ovulatory increase in progesterone seen in many species. Progesterone seems to decrease the steroidogenic activity of the ovarian tissue, perhaps offering an explanation for the gonadotropin resistance seen in corpus luteus bearing ovaries.

Ovarian steroidogenic enzyme activities during the rat estrous cycle

We have correlated the concentrations of serum LH, estradiol and progesterone with the activities of 2 ovarian steroid biosynthetic enzymes during the rat estrous cycle. Ovarian 3 beta-hydroxysteroid dehydrogenase isomerase (3-beta HSD) activity decreased from 29 +/- 6 nmol/mg protein/min (mean +/- SEM) in diestrus, to 7 +/- 0.4 nmol/mg protein/min in late proestrus (p less than 0.005), and subsequently increased to 36 +/- 9 nmol/mg protein/min in metestrus (p less than 0.01). Ovarian 17-hydroxylase (17-OH) activity decreased from early to late proestrus (3.3 +/- 0.2 vs 2.2 +/- 0.2 nmol/mg protein/min, p less than 0.0025), and subsequently increased to 3.9 +/- 0.2 in metestrus (p less than 0.001). Serum LH, estradiol and progesterone peaked during proestrus, and reached a nadir during estrus. We conclude that the activities of 3-beta HSD and 17-OH in the rat ovary vary markedly during the estrous cycle. These changes may underlie the pattern of steroid secretion characteristic of this process.

Developmental changes in rabbit and dog adrenal function: a possible homologue of adrenarche in the dog

Histologic, hormonal, and enzymatic studies were performed in the rabbit and dog to identify maturational changes similar to human adrenarche. Development of an adrenal reticular zone was observed in both the rabbit and dog, analogous to the change in the man. Plasma dehydroepiandrosterone (DHA) and androstenedione (delta 4-A) increased significantly in postpubertal compared to prepubertal male rabbits and dogs, but the increases were much smaller than those reported in man. Orchiectomy reduced plasma DHA and delta 4-A of adult rabbit and dog to near undetectable levels, suggesting a primarily testicular origin. The activities of adrenal microsomal 17-hydroxylase and 17,20-desmolase in the orchiectomized rabbit and dog were subsequently measured to explain this apparent low adrenal contribution to DHA and delta 4-A. Adrenal 17-hydroxylase activity in the rabbit ad 17,20-desmolase activity in both the rabbit and dog were significantly lower than in an adrenal androgen-secreting primate (cynomolgus macaque). Adrenal 17-hydroxylase activity in the dog, measured 1 wk after castration, doubled after sexual maturation (P less than 0.001). This change was paralleled by a significant rise in basal and ACTH-stimulated plasma 17-hydroxyprogesterone in the intact dog (P less than 0.05). Because adrenal 17-hydroxylase activity has been shown to increase during adrenarche in man, this change may be homologous to human adrenarche.

The developmental changes in plasma adrenal androgens during infancy and adrenarche are associated with changing activities of adrenal microsomal 17-hydroxylase and 17,20-desmolase

The plasma concentrations of dehydroepiandrosterone, androstenedione, and dehydroepiandrosterone sulfate decrease during the first year of life, remain low during childhood, and then increase during adrenarche. To determine whether alterations in adrenal enzyme activity might explain the changing secretory pattern of the adrenal androgens, we measured human adrenal microsomal 3 beta-hydroxysteroid dehydrogenase-isomerase, 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase activities. 12 adrenals from individuals aged 3 mo to 60 yr were studied. The patients were divided into three groups based upon the age of the patient when the adrenal glands were obtained: group 1, infants aged 3--8 mo (n = 3); group 2, preadrenarchal or early adrenarchal children aged 2--9 yr (n = 4); and group 3, adults aged 20--60 yr (n = 5). The mean activity of the 17,20-desmolase, 17-hydroxylase, and 21-hydroxylase fell by 50% and that of 3 beta-hydroxysteroid dehydrogenase-isomerase activity rose 80% from group 1 to 2. A fourfold increase in 17,20-desmolase (P less than 0.002) and 17-hydroxylase (P less than 0.001) activity and a doubling in 21-hydroxylase activity (P less than 0.005) occurred between groups 2 and 3. We conclude that the decline in plasma adrenal androgens after birth appears to be associated with a rise in 3 beta-hydroxysteroid dehydrogenase-isomerase and a fall in 17,20-desmolase and 17-hydroxylase activity. The subsequent increase in plasma adrenal androgen concentration during adrenarche is coincident with a rise in 17,20-desmolase and 17-hydroxylase activity.

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.

Effects of antihypertensive drugs on hepatic heme biosynthesis, and evaluation of ferrochelatase inhibitors to simplify testing of drugs for heme pathway induction

Effects of a series of antihypertensive drugs on the activity of delta-aminolevulinate synthase and on the formation of porphyrins and cytochrome P-450 were examined in the 18-day-old chick embryo liver in ovo. Hydralazine, pargyline, phenoxybenzamine, clonidine, and spironolactone were found to induce delta-aminolevulinate synthase in this system. These drugs therefore have the potential to precipitate clinical expression in human hereditary hepatic porphyrias and should be avoided or used with caution in patients with these disorders. Differential effects of these and other drugs were observed in the avian liver, in that delta-aminolevulinate synthase was more commonly induced than were porphyrins and cytochrome P-450; the synthase was usually highest 6-12 h after injection, whereas porphyrins and cytochrome P-450 were highest at 24 h. Furthermore marked porphyrin accumulation was not seen with many drugs that induce delta-aminolevulinate synthase and cytochrome P-450 but was more characteristic of compounds that reduced the metabolism of protoporphyrin to heme, such as 1,4-dihydro-3,5-dicarbethoxycollidine (DDC) and high doese of hydralazine. A sensitive and convenient method to test for capacity to induce heme biosynthesis was adapted for use in the chick embryo liver. This employed a relatively small "priming" dose (0.25 mg) of DDC given with a drug being tested and a fluorometric assay of porphyrins in a liver homogenate obtained at 24 h. This simple method should facilitate screening for those drugs which induce the synthesis of delta-aminolevulinate synthase and/or cytochrome P-450 and are potentially dangerous to patients with hereditary hepatic porphyria.

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.