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PubMed1992

[Non-surgical treatment of benign prostatic hypertrophy. Current status of the problem].

Benign prostatic hypertrophy is a highly prevalent disease, with a significant morbidity. Classical surgical therapy (open or transurethral adenomectomy) is very effective, but not without risks and complications. Better understanding of the pathogenesis of the disease have led to the development of several alternative treatments. Hormonal treatments are briefly reviewed, especially the preliminary results obtained with the 5-alpha-reductase inhibitors.

Androgen Antagonists↗

PubMed1991

[Activity of 5 alpha-reductase in human hyperplastic prostates].

To Study the relationship between the activity of 5 alpha-reductase and benign hyperplastic prostate (BPH), we have measured the T and dihydrotestosterone (DHT) contents and the specific activity of this enzyme in mechanically separated stroma and epithelium and in both the nucleus and cytoplasm from 20 cases of BPH and 7 cases of normal human prostate. The results were as follows: (1) The content of DHT in the BPH group was about 3 times higher than that in the N group. (2) The Michaelis constant (Km) of 5 alpha-reductase in both the stroma and epithelium was similar. (3) The specific activity of the enzyme in the stroma was higher than that in the epithelium, and in the BPH group, increased activity was found in the tissue or stroma but not in the epithelium. The activity was predominant in the nucleus. So our experiment supports that the elevation of the activity of 5 alpha-reductase may be related to the pathogenesis of human BPH.

Aged↗

PubMed1992

Early diagnosis and management of 5 alpha-reductase deficiency.

Two siblings of Pakistani origin, karyotype 46 XY, were born with predominantly female external genitalia with minute phallus, bifid scrotum, urogenital sinus, and palpable gonads. The older sibling at the age of 8 days showed an adequate testosterone response to human chorionic gonadotrophin (hCG) stimulation. The diagnosis of 5 alpha-reductase deficiency was made at age 6 years when no 5 alpha-reduced glucocorticoid metabolites were detectable in urine even after tetracosactrin (Synacthen) stimulation. In the younger sibling the diagnosis of 5 alpha-reductase deficiency was provisionally made at the early age of 3 days on the basis of high urinary tetrahydrocortisol (THF)/allotetrahydrocortisol (5 alpha-THF) ratio and this ratio increased with age confirming the diagnosis. Plasma testosterone: dihydrotestosterone (DHT) ratio before and after hCG stimulation was within normal limits at age 3 days but was raised at age 9 months. Topical DHT cream application to the external genitalia promoted significant phallic growth in both siblings and in the older sibling corrective surgery was facilitated. In prepubertal male pseudohermaphrodites with normal or raised testosterone concentrations, phallic growth in response to DHT cream treatment could be an indirect confirmation of 5 alpha-reductase deficiency.

Administration, Topical↗

PubMed1992

Expression of 4-ene steroid 5 alpha-reductase messenger ribonucleic acid in the rat epididymis during postnatal development.

The regulation of epididymal 5 alpha-reductase mRNA is multifactorial and segment-specific. To further investigate the regulation of the message for the enzyme, the expression of 5 alpha-reductase mRNA in the rat epididymis was studied as a function of postnatal development. Developmental changes in 5 alpha-reductase mRNA concentrations were assessed by probing Northern blots with the full-length cDNA for rat steroid 5 alpha-reductase. In the first experiment the effect of postnatal age on 5 alpha-reductase mRNA concentrations in the caput-corpus and cauda epididymides was studied. Male rats, taken at 1-week intervals between the ages of 7-91 days, were used. In both epididymal regions, the mRNA for 5 alpha-reductase was present at all ages examined; it appeared in the immature animal at least 2 weeks before detectable 5 alpha-reductase enzyme activity. In the caput-corpus epididymidis, mRNA levels for 5 alpha-reductase decreased by half between postnatal days 7 and 21, rose 5-fold by day 56, and then remained constant through day 91. No change with postnatal age, however, was observed in the cauda epididymidis. In the second experiment, the longitudinal distribution of 5 alpha-reductase mRNA on postnatal days 21, 42, 49, 56, 77, and 91 was studied. The mRNA levels for 5 alpha-reductase increased remarkably, by 6- to 7-fold, in the initial segment of the caput epididymidis between postnatal days 21 and 42 and stayed constant thereafter. However, no significant change comparable to that found in the initial segment was observed in the adjacent proximal caput region or in any of the other epididymal segments. Thus, the 5-fold rise in 5 alpha-reductase mRNA concentrations that occurred in the caput-corpus epididymidis in the first experiment can be attributed solely to changes in the initial segment. We conclude that steady state concentrations of epididymal 5 alpha-reductase mRNA vary dramatically at different postnatal ages and are highly specific with respect to epididymal segment.

Aging↗

PubMed1992

Antihormonal properties of some new A-homo-B, 19-dinor steroids of the androstane series.

On solvolysis of Westphalen-type steroids with a leaving group in the position 6 beta (e.g., 2), products of elimination (followed by rearrangement and fragmentation of the steroid skeleton) were prepared (e.g., 4 and 5). These products were subsequently converted to suitable analogs of the compound, which has been reported to promote hair growth (1). Compounds 11 to 13 exhibited strong antiandrogenic activity in vivo; however, this activity could not be interpreted either in terms of inhibition of 5 alpha-reductase or by strong binding to an androgen receptor.

Androgen Antagonists↗

PubMed1992

Effects of the new steroidal antiandrogen TZP-4238 on hormone-induced canine prostatic hyperplasia.

The effects of the new steroidal antiandrogen TZP-4238 on hormone-induced canine prostatic hyperplasia (BPH) were studied in comparison with those of chlormadinone acetate (CMA), a steroidal antiandrogen used in Japan. One- to 2-year-old beagle dogs were castrated and administered 75 mg/week of androstanediol (A-diol) plus 0.75 mg/week of estradiol (E2) for 25 weeks. These dogs were treated orally with placebo, 0.5 mg/kg/day of TZP-4238, 0.1 mg/kg/day of TZP-4238, and 2.5 mg/kg/day of CMA, respectively, for 21 weeks after 4 weeks treatment with A-diol plus E2. Treatment with 0.5 mg/kg/day of TZP-4238 or 2.5 mg/kg/day of CMA suppressed prostatic growth, and treatment with 0.1 mg/kg/day of TZP-4238 suppressed prostatic growth slightly. Treatment with 0.5 mg/kg/day of TZP-4238 decreased 5 alpha-reductase activity, DHT content, and nuclear androgen receptor (AR) content in the prostate, and treatment with 0.1 mg/kg/day of TZP-4238 or 2.5 mg/kg/day of CMA also decreased or tended to decrease these parameters. In conclusion, TZP-4238 and CMA were effective in inhibiting the growth of hormone-induced canine BPH, and TZP-4238 was at least 5 times more potent than CMA. TZP-4238 inhibited prostatic growth by decreasing prostatic androgen content and the androgen-AR complex. TZP-4238 decreased 5 alpha-reductase activity by prevention of the androgen action described above.

Androstane-3,17-diol↗

PubMed1992

Intracellular signalling systems controlling the 5 alpha-reductase in glial cell cultures.

Glial cells are able to metabolize testosterone into DHT through the action of the enzyme 5 alpha-reductase. DHT may be further processed to 3 alpha-diol by the 3 alpha-hydroxysteroid-dehydrogenase. The aim of this study was to analyze if a modulation of two second messenger systems might be able to modify the 5 alpha-reductase and the 3 alpha-hydroxysteroid-dehydrogenase activities present in glial cells. To this purpose, the formation of DHT has been measured in rat glial cell cultures after different time of exposure to TPA, 4 alpha-Ph, an active and an inactive phorbol ester respectively, and 8-Br-cAMP. The results obtained indicate that the formation of DHT is not modified by the addition of phorbol esters. On the contrary, a statistically significant increase of 5 alpha-reductase activity, over control levels, has been observed after 6, 12, and 24 h of incubation with 8-Br-cAMP (10(-3) M). The effect of the cAMP analogue appears to be specific for the 5 alpha-reductase, since the 3 alpha-hydroxysteroid-dehydrogenase did not show any variation after exposure to the drug. In conclusion, the present data suggest that proteinkinase A (PKA) might be involved in the control of the 5 alpha-reductase in glial cells. It is postulated that nervous inputs utilizing cAMP as the second messenger might modify the activity of this enzyme in glial cells.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1992

5-alpha-reductase activity and risk of prostate cancer among Japanese and US white and black males.

The incidence of prostate cancer varies widely between countries and ethnic groups. Black-Americans have the highest incidence rates world wide, whereas native Japanese have among the lowest. The reasons for this risk differential are unknown, although we have previously shown that higher circulating testosterone concentrations in young adult black men compared with young adult white men may explain the underlying differences in subsequent prostate cancer incidence between these two populations. We have now compared serum testosterone concentrations in young adult Japanese men with those of young adult whites and blacks, but found no significant differences. However, these white and black men had significantly higher values of 3 alpha, 17 beta androstanediol glucuronide (31% and 25% higher, respectively) and androsterone glucuronide (50% and 41% higher, respectively) than Japanese subjects. These two androgens are indices of 5 alpha-reductase activity. Our results raise the possibility that reduced 5 alpha-reductase activity has a role in producing the low prostate cancer incidence rates among Japanese. This finding may have important implications for prostate cancer prevention.

Adult↗

PubMed1992

The 5 alpha-reductase in the brain: molecular aspects and relation to brain function.

All the classes of hormonal steroids physiologically produced in the body (androgens, estrogens, progestagens, and corticosteroids) are able to exert important effects on the brain, but the mechanisms of their actions are not always well understood. Steroids may interact with intracellular receptors to activate the genome, but some of their effects are probably extragenomic and involve interactions with cellular membranes. Moreover, not all the steroids act always in their native molecular form; a large group of them must actually be transformed into "active" metabolites. This may occur at the level of their respective target structures. For example, androgens are metabolized in the brain into estrogens and into 5 alpha-reduced androgens, like 5 alpha-androstan-17 beta-ol-3-one (dihydrotestosterone; DHT) and 5 alpha-androstan-3 alpha, 17 beta-diol (3 alpha-diol). Progesterone, and possibly corticosteroids, may also be transformed into their corresponding 5 alpha-reduced metabolites. Also the cellular target (neurons and/or glial cells) of the hormonal steroids in the brain is not always clear. This review analyzes in detail one of the two major enzymatic systems that transform steroids in the brain, namely the 5 alpha-reductase-3 alpha-(3 beta)-hydroxysteroid dehydrogenase pathway. An active 5 alpha-reductase-3 alpha-hydroxysteroid dehydrogenase system is widely distributed in practically all CNS structures in all phases of development. In the brain, this enzymatic system is not regulated by castration or sex steroid administration; furthermore, neural inputs seem to be ineffective at the hypothalamic level. A recent interesting finding is the presence of high concentrations of the 5 alpha-reductase in the white matter. This probably is due to the fact that the white matter is particularly rich in myelin membranes, with which the enzymatic activity appears to be associated. An active 5 alpha-reductase activity has also been shown to be present in peripheral myelinated nerves. The localization in myelin membranes may suggest a possible involvement of 5 alpha-reduced metabolites of the different steroids in the process of myelination. The presence of the 5 alpha-reductase was analyzed in neurons, astrocytes, and oligodendrocytes isolated from the brains of male rats, as well as in neurons and glial cells grown in culture. Neurons appear to be more active than glial cells in converting testosterone into DHT. Only neurons possess aromatase activity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

Intrauterine position effects on steroid metabolism and steroid receptors of reproductive organs in male mice.

Mice differ in their adult reproductive characteristics as a function of whether they developed in utero between two male fetuses (2M males), which have higher testosterone levels, or between two female fetuses (0M males), which have higher estradiol levels. The present study was designed to further characterize biochemical parameters of 2M and 0M adult male mice. Activities of testicular steroidogenic enzymes, namely delta 5-3 beta-hydroxysteroid dehydrogenase/isomerase, 17 alpha-hydroxylase, and C17,20-lyase (C21SCC P450), were measured by means of radiometric assays and HPLC fractionation of substrate and products. Activity of 5 alpha-reductase in both seminal vesicle and prostate was measured by similar techniques. Estrogen and androgen receptor concentrations, which indicate capacity to respond to steroid hormones, were also examined in the accessory sex organs. For both seminal vesicle and prostate, 5 alpha-reductase activities were approximately 60% greater in 2M males than in 0M males, indicating greater capacity to form dihydrotestosterone from testosterone in organs from 2M mice. No significant differences were found in testicular steroidogenic enzymes between 2M and 0M animals, whereas the trend for all three activities was higher for 2M males than for 0M males. While no differences were found in estrogen receptor concentrations, 0M prostates had three times the concentration of androgen receptors (occupied receptors) compared to 2M prostates. Our findings suggest that intrauterine fetal position exerts a significant influence on subsequent adult androgen metabolism and androgen responsiveness in reproductive organs of adult male mice.

Aldehyde-Lyases↗

PubMed1992

Syndromes of androgen resistance.

Androgen resistance can be divided into two broad categories: deficiency in 5 alpha-reductase and defects in the androgen receptor. Studies of these two disorders have provided insight into both the normal pathway of androgen action and into the pathogenesis of abnormal sexual development. 5 alpha-Reductase deficiency is a rare autosomal recessive disorder involving the 5 alpha-reductase 2 enzyme; affected males exhibit a defect in virilization most evident as impairment of the virilization of the external genitalia and urogenital sinus. Disorders of the androgen receptor in genetic males cause a spectrum of developmental abnormalities that vary from phenotypic females to men with mild defects in virilization. On functional grounds we have divided these defects into absence of receptor function, qualitatively abnormal receptors, quantitative defects in receptor amount, and apparently normal receptor. Cloning of the cDNA for the receptor and application of the polymerase chain reaction techniques for sequencing of mutants made it possible to analyze these defects at the molecular level. It is now apparent that the functional categorization underestimated the complexity of the mutations. Indeed, major gene deletions and/or rearrangements, single amino acid substitutions, and premature termination codons all can cause variably severe functional abnormalities.

Androgens↗

PubMed1992

Effect of finasteride, a 5 alpha-reductase inhibitor, on serum gonadotropins in normal men.

Testosterone exerts negative feedback control on gonadotropin secretion either directly, after aromatization to estradiol, or after 5 alpha-reduction to dihydrotestosterone (DHT). Conflicting data exist as to the role of DHT in the modulation of this negative feedback. To determine whether suppression of endogenous DHT alters gonadotropin secretion, we gave the selective 5 alpha-reductase inhibitor finasteride (5 mg daily), or placebo, to 20 healthy men for 28 days. Basal and GnRH-stimulated LH, bioactive LH, FSH, testosterone, and DHT levels were measured before and after 14 and 28 days of treatment. Basal DHT fell from 1.1 +/- 0.2 to 0.15 +/- 0.04 nmol/L after 28 days of finasteride treatment. A significant rise in baseline testosterone from 17.6 +/- 2.0 to 18.3 +/- 2.3 nmol/L was seen at 14 days (P = 0.046), but not at 28 days. No significant changes were seen in either basal or GnRH-stimulated gonadotropin levels on any day. We conclude that suppression of serum DHT levels with 5 mg finasteride daily in healthy young men has no discernible effect on serum gonadotropin levels.

Adult↗

PubMed1992

Determination of L-654,066, a new 5 alpha-reductase inhibitor in plasma by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry.

L-654,066 is a new 5 alpha-reductase inhibitor. A sensitive and specific assay based on combined liquid chromatography/mass spectrometry has been developed for the determination of this drug candidate in plasma. The analyte was isolated from plasma by solid-phase extraction on a C-18 cartridge. A related substance, L-683,838, was used as the internal standard. Extracts were chromatographed on a 5 cm C18 reverse-phase high-performance liquid chromatography column interfaced via the heated nebulizer probe to a corona discharge chemical ionization source. The mass spectrometer was operated in the positive ion tandem mode. The method has sufficient sensitivity, precision, accuracy and selectivity for the analysis of clinical samples containing L-654,066 at concentrations in the range 0.5-20 ng ml-1. The chromatographic run time is less than 2 min.

Azasteroids↗

PubMed1992

[Intracellular effect of the ventral prostate in zinc deficient rats].

Concentration of androgens, binding-sites of androgen-receptors as well as the activity of 5 alpha-reductase of the ventral prostates have been studied in the zinc-deficient rats. Eight-week-old Sprague-Dawley rats were housed individually in cages and divided into two groups, I. Experimental group, redivided into 2 sub-groups: (a) maintained on a zinc-deficient diet for 3 and 6 weeks, (b) zinc-deficient diet for 3 weeks then re-fed normal diet, II. Control group fed with normal diet. The ventral prostates were dissected free and homogenized after the rats sacrificed. Androgens and androgen-receptor were quantified by RIA and "exchange assay" respectively. The result obtained from the zinc-deficient rats were significantly different (P less than 0.05) from those of the control group 1. The zinc-deficient 3 and 6 weeks rats showed the plasma testosterone concentration decreased by 18% and 15%. 2. The cytosolic (fmo1/mg protein) dihydrotestosterone and its binding receptor were decreased by 10-15% and 28-30%, respectively. 3. The nuclear (fmo1/mg DNA) dihydrotestosterone and its receptor protein were ony 2-3% and 3-3.6% of the control group respectively. 4. Studies on the androgen metabolism showed that the metabolite, dihydrotestosterone (fmo1/mg protein) of rats with zinc-deficient 6 weeks was only 48% of the control group. 5. The prostate weight (mg) of zinc-deficient rats was 45-50% of the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Inhibition of 3 alpha-hydroxysteroid oxidoreductase and 5 alpha-reductase activity by antiandrogens and indomethacin in the rat prostate.

We studied the effects of antiandrogens in vitro on inhibition of 3 alpha-hydroxysteroid oxidoreductase (3 alpha-HSOR) and 5 alpha-reductase activities in the rat prostate. Kinetic and inhibition experiments were analyzed by thin layer chromatography. Cyproterone acetate (CA), chlormadinone acetate (CMA), and TZP-4238 (TZP), which is more potent than other antiandrogens, were used as inhibitors and were compared with indomethacin IND, which is a recognized 3 alpha-HSOR inhibitor. The IC50S of CA, CMA, IND, and TZP for 3 alpha-HSOR reductase in cytosol were about 5, 10, 10, and 100 microM, respectively, and inhibition was competitive. The IC50 of IND for 3 alpha-HSOR reductase in microsomes was 20 microM. The IC50S of other inhibitors were > 100 microM, and inhibition was noncompetitive. The IC50S of CA, CMA, IND, and TZP for 3 alpha-HSOR oxidase in cytosol were > 100 microM, and inhibition was competitive or noncompetitive. Inhibition of 3 alpha-HSOR oxidation was not observed in microsomes. The difference between these inhibition patterns suggests that there may be 4 isoenzymes in rat prostatic tissue. The IC50S of MK-906, CMA, and TZP for 5 alpha-reductase in prostate homogenate were about 0.01, 200, and 200 microM, respectively.

3-Hydroxysteroid Dehydrogenases↗

PubMed1992

Effects of 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one on steroidogenesis in gonads of rat fetuses.

1. The effect of 5 alpha-reductase inhibitor 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one (4-MA) on the fetal rat steroidogenesis was examined. 18- and 20-day-old fetal ovaries were incubated in the presence of dcAMP (1 mM) and spironolactone (10 mM) and progesterone production was assessed with and without 4-MA (0.01-50 microM). 2. High concentrations of 4-MA significantly decreased the production of progesterone. 3. Similar inhibition of the testosterone synthesis was observed in 16-day-old fetal testes explanted either in the control medium (M199) or in the presence of LH (100 ng/ml) when treated with 4-MA. The effect was rapidly reversible in both gonads.

Androgen Antagonists↗

PubMed1992

Cutaneous application of an androstenedione gel as an in vivo test of 5 alpha-reductase activity in women.

OBJECTIVE: Assessment of an in vivo test for 5 alpha-reductase activity using serum markers, 5 alpha-androstane-3 alpha,17 beta-diol glucuronide and androsterone glucuronide, after the cutaneous application of androstenedione (A). DESIGN: An A gel was applied for 6 days to the skin of normal women, male volunteers, and hirsute and nonhirsute patients with polycystic ovarian syndrome (PCOS). Blood samples were obtained at baseline and on day 6 of the A gel application. Blood samples were assayed for A, 5 alpha-androstane-3 alpha,17 beta-diol glucuronide, and androsterone glucuronide. In three hirsute women, the protocol was followed before and after receiving an oral contraceptive (OC) and spironolactone 200 mg/d for 3 months. SETTING: The study was performed in the outpatient clinic of the Division of Reproductive Endocrinology and Infertility, Women's Hospital of the Los Angeles County and University of Southern California Medical Center in Los Angeles, California. PATIENTS, PARTICIPANTS: A total of eight nonhirsute patients with PCOS, seven hirsute patients with PCOS, and six male volunteers were enrolled in the study. Five normal women served as a control group. MAIN OUTCOME MEASURE: Serum A increased after 6 days by a similar magnitude in all groups. Serum androsterone glucuronide showed a significant increase from baseline only in the hirsute group (P < 0.03), whereas the increase in 5 alpha-androstane-3 alpha,17 beta-diol glucuronide was not statistically significant. RESULTS: The ratio of the increases in serum androsterone glucuronide over serum A was significantly higher in the hirsute group (P < 0.02). In the three hirsute patients who were placed on an OC and spironolactone, serum 5 alpha-androstane-3 alpha,17 beta-diol glucuronide and androsterone glucuronide decreased after 3 months and did not increase with application of the gel for another 6 days. CONCLUSION: The cutaneous application of A provides a useful assessment of in vivo 5 alpha-reductase activity. However, because we found that A absorption varied considerably (30% to 62%), we suggest that this in vivo test may not provide more information than baseline determinations of 5 alpha-androstane-3 alpha,17 beta-diol glucuronide and androsterone glucuronide. It may, however, be useful as a parameter for assessing the effectiveness of various treatment regimens for hirsutism.

Administration, Cutaneous↗

PubMed1992

Identification and selective inhibition of an isozyme of steroid 5 alpha-reductase in human scalp.

Steroid 5 alpha-reductase (EC 1.3.1.22) catalyzes the reduction of testosterone to dihydrotestosterone. The 5 alpha-reductase found in human scalp has been compared with the enzyme found in prostate. The scalp reductase has a broad pH optimum centered at pH 7.0. This is distinctly different from the pH optimum of 5.5 observed with the prostatic form of the enzyme. These enzymes also differ in the Km for testosterone, which is 25-fold higher for the scalp reductase. The most significant difference between the two enzymes is their affinity for inhibitors. Two 4-azasteroids and a 3-carboxyandrostadiene are potent inhibitors of the prostatic reductase but are weak inhibitors of the scalp reductase. In contrast, several N-4-methylazasteroids are good inhibitors of the scalp reductase. These findings support a proposal that different isozymes of 5 alpha-reductase may exist in scalp and prostate. The scalp reductase was also compared to 5 alpha-reductase 1, one of the two enzymes recently cloned from human prostate [Andersson, S. & Russell, D. W. (1990) Proc. Natl. Acad. Sci. USA 87, 3640-3644; and Andersson, S., Berman, D. M., Jenkins, E. P. & Russell, D. W. (1991) Nature (London) 354, 159-161]. The characteristics of the cloned reductase 1 are comparable to those of the scalp reductase.

Animals↗