Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hydroxysteroids”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed2004

Steroid profiles of transgenic tobacco expressing an Actinomyces 3-hydroxysteroid oxidase gene.

Previously, we have shown that the expression of a 3-hydroxysteroid-oxidase gene in transgenic tobacco initiated a series of biochemical events leading to the conversion of sterol to stanol. As a result, the plants maintained a diminished sterol pool and a modified relative sterol ratio but demonstrated no observable morphological abnormalities. The maintenance of normal higher plant physiology in the absence of particular sterols or in the presence of modified sterol ratios is controversial. In this report, we present additional biochemical and physiological characteristics of transgenic tobacco expressing an Actinomyces 3-hydroxysteroid-oxidase gene. The total steroid accumulated in the transgenic plants is 6-fold higher than in control plants and consists of sterol, 3-ketosteroid and stanol. The relative abundance of sterols within whole plant and individual organs is grossly altered as ethylated side chain sterols account for 99% of the total sterol pool in the transgenic tobacco. Stigmasterol is readily apparent in all tissues and cholesterol is found at measurable levels in specific organs, while campesterol and sitosterol are detected at trace levels in the transgenic plants. Stanols and 3-ketosteroids accumulate in all tissues and represent 77% of the measurable steroid pool in the transgenic plants. The sum of sterol, the respective 3-ketosteroid plus stanol provide a relative abundance of steroid, which is similar to the abundance of sterol accumulated in control tissue. In vitro photosynthetic electron transport measurements demonstrate altered activity of chloroplasts under a variety of reaction conditions, indicating a link between the modified steroid pool and a modulation of chloroplast membrane function.

3-Hydroxysteroid Dehydrogenases↗
PubMed2006

Synthesis of pyridine-carboxylate derivatives of hydroxysteroids for liquid chromatography-electrospray ionization-mass spectrometry.

Synthesis and liquid chromatography-electrospray ionization-mass spectrometric (LC-ESI-MS) behaviors of the picolinoyl, 6-methylpicolinoyl, nicotinoyl, 2-methoxynicotinoyl and isonicotinoyl derivatives of the hydroxysteroids estrone, estradiol, 3beta-hydroxyandrost-5-en-17-one (dehydroepiandrosterone) and testosterone in positive mode were investigated. Each steroid was converted to the corresponding pyridine-carboxylate derivative by the acyl chloride method or the mixed anhydride method using the corresponding free acids and 2-methyl-6-nitrobenzoic anhydride; in each case, the latter method principally gave a better yield. The pyridine-carboxylate derivative of each steroid exhibited a clear single peak in liquid chromatography with a reversed phase column and CH(3)CN-0.1% CH(3)COOH as a mobile phase. The positive-ESI-mass spectra of the picolinoyl, 6-methylpicolinoyl and 2-methoxynicotinoyl derivatives showed a predominance of [M+H](+), whereas [M+H+CH(3)CN](+) was observed with high intensity in the nicotinoyl and isonicotinoyl derivatives. Even in the case of estradiol, with its two hydroxyl groups, a single charged ion of [M+H](+) or [M+H+CH(3)CN](+) was observed in the positive-ESI-mass spectrum of each derivative. The results revealed that picolinoyl derivatization is a simple and versatile method suitable for the sensitive and specific determination of hydroxysteroids by LC-ESI-MS (selected reaction monitoring).

Calibration↗
PubMed2002

Effect of a peroxisome proliferator on 3 beta-hydroxysteroid dehydrogenase.

To better understand the changes that occur following exposure to peroxisome proliferators, we utilized mRNA differential display and microarray to screen for peroxisome proliferator target genes apart from those involved in lipid metabolism in male C57B6 mice by using the ubiquitous plasticizer, di(2-ethylhexyl)phthalate (DEHP). One noted change was the dose-dependent suppression of the mouse hormone metabolizing 3 beta-hydroxysteroid dehydrogenase V (HSD3b5), which is specifically expressed in the male mouse liver. Northern analysis showed that HSD3b5 mRNA levels decreased dramatically upon one-day exposure to 2.0% dietary DEHP, and were nearly undetectable by one week of treatment. Food restriction also significantly suppressed HSD3b5 expression; however, in this case the suppression was delayed and to a lesser extent. Another mouse 3 beta-hydroxysteroid dehydrogenase, HSD3b4, predominantly expressed in kidneys, was also regulated by DEHP and food restriction. The sex-specific gene, HSD3b5, was affected more by DEHP and food restriction than the tissue-specific gene, HSD3b4.

3-Hydroxysteroid Dehydrogenases↗
PubMed2003

Steroid-binding site residues dictate optimal substrate positioning in rat 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD or AKR1C9).

Rat liver 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD or AKR1C9), a member of the aldo-keto reductase (AKR) superfamily, plays a pivotal role in the inactivation of circulating steroid hormones. It is the most thoroughly characterized HSD of the AKR superfamily and can be used as a template for structure-function studies in other AKR members such as rodent and human 3alpha-, 17beta- and 20alpha-HSDs. Based on the crystal structure of the E.NADP(+) testosterone ternary complex, there are ten residues that line the testosterone binding cavity: T24, L54, Y55, H117, F118, F129, T226, W227, N306 and Y310. Each residue in the cavity, except for the catalytic residues Y55 and H117, was systematically mutated to alanine to determine the role of the individual residues in steroid recognition. Binding data and kinetic parameters (K(d), k(cat), K(m) and k(cat)/K(m)) of the homogeneous mutants were compared with that of the wild type (WT) enzyme. Titration of the intrinsic tryptophan fluorescence with NADPH demonstrated that cofactor binding was unaltered. However, binding of the steroid hormones testosterone and progesterone to the E.NADPH binary complex was affected to varying degrees. The largest effects on K(d) were an 8-fold decrease in affinity for testosterone and a 50-fold decrease in affinity for progesterone. The mutants bound both hormones in the same rank-order except for W227A, where the binding of progesterone was more adversely affected. A series of 3alpha-hydroxysteroid substrates (A/B trans- and cis-ring fused C(19) and C(21) steroids) were used to determine the ability of each mutant to catalyze steroid turnover. The alanine mutants that retained k(cat)/K(m) values similar to WT were those in which alanine substituted short polar residues such as T24A and T226A. The mutants with the lowest catalytic efficiencies were those in which alanine substituted aromatic residues such as W227A and F129A. The loss in catalytic efficiency was due to large changes in k(cat) (up to 1000-fold), but not K(m). Molecular modeling of the alanine mutants showed that changes in the reaction trajectory defined by the angles and distances by groups that participate in catalysis correlate with changes in k(cat). These results highlight the importance of steroid binding site residues in dictating the proper orientation of substrates to achieve high catalytic turnover while having minimal effects on hormone affinity.

Alanine↗
PubMed2003

17-beta-Hydroxysteroid dehydrogenase type 1: computational design of active site inhibitors targeted to the Rossmann fold.

17-beta-Hydroxysteroid dehydrogenase type 1 (17betaHSD1), also called estradiol dehydrogenase, catalyzes the NADPH-dependent reduction of the weak estrogen, estrone, into the more potent estrogen, 17-beta-estradiol. 17betaHSD1 is an attractive drug target in hormone-sensitive breast cancer. Past efforts to develop selective inhibitors of 17betaHSD1 have focused on design of substrate analogs. It is challenging to develop steroid analogs that are devoid of any undesired biological activity. 17betaHSD1 is a member of the short-chain dehydrogenase/reductase (SDR) superfamily that includes many hydroxysteroid dehydrogenases. Members of the SDR family bind NAD(P)(H) in a motif that is a modified Rossmann fold. We demonstrated previously that the Rossmann folds of classical dehydrogenases can be selectively inhibited by derivatives and analogs of the natural product gossypol. In this study, we have addressed the question whether the modified Rossmann fold in 17betaHSD1 is a target for identification of lead compounds for structure-based drug design. 17betaHSD1 was purified from human placenta. 17betaHSD1 is inhibited by derivatives of gossypol with dissociation constants as low as 2 microM. Inhibition is competitive with the binding of cofactor. Molecular modeling studies using the published coordinates of human 17betaHSD1 suggest that these inhibitors occupy the modified Rossmann fold at the nicotinamide end of the dinucleotide-binding site, extending towards the substrate site. A computational approach was used to design potential new inhibitors of 17betaHSD1. The results suggest not only that derivatives of gossypol represent attractive lead compounds for structure-based drug design but also suggest that appropriate incorporation of a substrate analog into the design of these Rossmann fold inhibitors may provide pan-active site inhibitors that span the cofactor and substrate site, potentially offering specificity and increased potency.

17-Hydroxysteroid Dehydrogenases↗
PubMed1975

Biologic effects following active immunization with delta 5-3 beta-hydroxysteroid dehydrogenase.

Immunization of female rats with crude preparations of delta 5-3 beta-hydroxysteroid dehydrogenase combined with complete Freund's adjuvant resulted in suppression of the endogenous enzyme activity in the ovarian interstitial tissue and the corpora lutea. As a result, estrous cyclicity, nidation, or maintenance of pregnancy was adversely affected in proportion to the level of the antibody to the enzyme following the series of immunizations. On the basis of the biologic response, it can be assumed that progesterone synthesis was reduced as a result of neutralization of enzyme action in the ovary by the formation of antibodies to the delta 5-3 beta-hydroxysteroid dehydrogenase. Further studies are required to verify this assumption.

3-Hydroxysteroid Dehydrogenases↗
PubMed1976

Histochemical demonstration of delta5-3beta-hydroxysteroid dehydrogenase activity in ovaries of intact infant mice and mice treated with anti-rat gonadotropin.

The localization of delta5-3beta-hydroxysteroid dehydrogenase activity was demonstrated histochemically in the neonatal mouse ovary. Histochemical studies were also undertaken in an attempt to investigate the effects of gonadotropic deprivation from birth to age 7 or 14 days on the distribution of enzymatic activity. Between birth and the age of 2 weeks, delta5-3beta-hydroxysteroid dehydrogenase activity was observed in virtually all follicles. In the newborn mouse ovary, the activity was found in granulosa cells of follicles developing in the center of the organ. On the 14th day, the granulosa cells of some apparently normal follicles histochemically were relatively inert, while others, obviously atretic, demonstrated extensive, localized, diformazan granules. Deprivation of endogenous circulating gonadotropin by daily injections of anti-rat gonadotropin had specific effects on follicular development and histochemical patterns in animals deprived of gonadotropins for 14 days but not for only 7 days.

Animals↗
PubMed2000

[Decreased activity of 11-beta-hydroxysteroid dehydrogenase in patients with Cushing's syndrome].

BACKGROUND: To study 11 beta-hydroxysteroid dehydrogenase activity in Cushing's syndrome. PATIENTS AND METHOD: Measurements of free cortisol, cortisone, tetrahydrocortisol and tetrahydrocortisone in 24 h urine samples of patients with Cushing's syndrome and controls. RESULTS: The cortisol to cortisone and tetrahydrocortisol to tetrahydrocortisone relationship was significant (in controls, r = 0.70; p < 0.0001, and r = 0.75; p < 0.0001) respectively, but it was not in patients with Cushing's syndrome. CONCLUSIONS: 11 beta-hydroxysteroid dehydrogenase activity is decreased in patients with Cushing's syndrome.

Adrenocorticotropic Hormone↗
PubMed2001

Chemical synthesis of 16beta-propylaminoacyl derivatives of estradiol and their inhibitory potency on type 1 17beta-hydroxysteroid dehydrogenase and binding affinity on steroid receptors.

The 17beta-hydroxysteroid dehydrogenases (17beta-HSDs) are members of a family of enzymes that catalyze the interconversion of weakly active sexual hormones (ketosteroids) and potent hormones (17beta-hydroxysteroids). Among the known isoforms of 17beta-HSD, the type 1 catalyzes the NAD(P)H-mediated reduction of estrone (E(1)) to estradiol (E(2)), a predominant mitogen for the breast cancer cells. Therefore, the inhibition of this particular enzyme is a logical approach to reduce the concentration of estradiol in breast tumors. To develop inhibitors of type 1 17beta-HSD activity, we hypothesized that molecules containing both hydrophobic and hydrophilic components should be interesting candidates for interacting with both the steroid binding domain and some amino acid residues of the cofactor binding domain of the enzyme. Firstly, a conveniently protected 16beta-(3-aminopropyl)-E(2) derivative was synthesized from commercially available E(1). Then, a representative of all class of NHBoc-protected amino acids (basic, acid, aromatic, aliphatic, hydroxylated) were coupled using standard procedures to the amino group of the precursor. Finally, cleavage of all protecting groups was performed in a single step to generate a series of 16beta-propylaminoacyl derivatives of E(2). The enzymatic screening revealed that none of the novel compounds can inhibit the reductive activity of type 1 17beta-HSD. On the other hand, all of these E(2) derivatives did not show any significant binding affinity on four steroid receptors including the estrogen receptor. Additional efforts aimed at improving the inhibitory potency of these steroidal derivatives on type 1 17beta-HSD without providing estrogenic activities is under investigation using a combinatorial chemistry approach.

17-Hydroxysteroid Dehydrogenases↗
PubMed1981

Purification of 20 alpha-hydroxysteroid oxidoreductase from bovine fetal erythrocytes.

NADPH-dependent 20 alpha-hydroxysteroid oxidoreductase (20 alpha-HSD; EC 1.1.1.149) from bovine fetal erythrocytes was obtained for the first time free of hemoglobin by a new 2,500-fold purification scheme. This was achieved by a sequence of calcium phosphate gel absorption, ammonium sulfate fractionation, and affinity chromatography. The present results lead us to believe that the NADPH-dependent 3 beta-hydroxysteroid oxidoreductase activity, which was co-purified with 20 alpha-activity, may originate at the active site of 20 alpha-HSD (2).

20-Hydroxysteroid Dehydrogenases↗
PubMed1997

The regulation of 3 beta-hydroxysteroid dehydrogenase expression.

3 beta-Hydroxysteroid dehydrogenasel delta 5-->4-isomerase (3 beta-HSD) catalyzes the formation of delta 4-3-ketosteroids from delta 5-3 beta-hydroxysteroids, an obligate step in the biosynthesis not only of androgens and estrogens but also of mineralocorticoids and glucocorticoids. The enzyme is expressed in the adrenal cortex and in steroidogenic cells of the gonads, consistent with this role. However, 3 beta-HSD is also expressed in many other tissues, such as the liver and kidney, where its function is not entirely clear. It is established that a family of closely related genes encode for 3 beta-HSD. The various 3 beta-HSD isoforms are expressed in a tissue-specific manner involving separate mechanisms of regulation. The human type I 3 beta-HSD is expressed at high levels in syncytial trophoblast and in sebaceous glands, and the type II isoform is almost exclusively expressed in the adrenal cortex and gonads. An important feature in liver and kidney (at least of hamster, mouse, rabbit, and rat) is the sexual dimorphic nature of 3 beta-HSD expression. We briefly review studies on the regulation of the human 3 beta-HSD I and II genes in human trophoblast and adrenal cortex and extend this to discuss the rat 3 beta-HSD I gene expressed in adrenals and gonads. The complexity of 3 beta-HSD expression through multiple signaling pathways acting on a multigene family of enzymes may contribute importantly to the diverse patterns and locations of steroid hormone biosynthesis.

3-Hydroxysteroid Dehydrogenases↗
PubMed2001

Characterization of the oxidative 3alpha-hydroxysteroid dehydrogenase activity of human recombinant 11-cis-retinol dehydrogenase.

11-cis-Retinol dehydrogenase catalyzes the oxidation of cis-retinols, a rate-limiting step in the biosynthesis of 9-cis-retinoic acid. It is also active toward 3alpha-hydroxysteroids, and thus might be involved in steroid metabolism. To better understand the role of this enzyme, we produced stable transfectants expressing 11-cis-retinol dehydrogenase in human embryonic kidney 293 cells. In vitro enzymatic assays have demonstrated that, with an appropriate exogenous cofactor, the enzyme catalyzes the interconversion of 5alpha-androstane-3alpha,17beta-diol and dihydrotestosterone and that of androsterone and androstanedione. However, using intact transfected cells, we found that the enzyme catalyzes reactions only in the oxidative direction. Thus, it is possible that 5alpha-androstane-3alpha,17beta-diol (an inactive androgen) can be converted into dihydrotestosterone, the most potent androgen, by the action of 11-cis-retinol dehydrogenase. This reaction could constitute a non-classical pathway of production of active androgens in the peripheral tissues. We also showed that all-trans-, 9-cis- and 13-cis-retinol inhibit the oxidative 3alpha-hydroxysteroid steroid activity of 11-cis-retinol dehydrogenase with similar K(i) values. Since all-trans-retinol is a precursor of cis-retinols, its inhibitory effect on the activity suggests that it could play an important role in modulating the formation of 9-cis-retinoic acid. In addition, we examined the effect of several known enzyme modulators, namely carbenoxolone, phenylarsine oxide and phosphatidylcholine, on 11-cis-retinol dehydrogenase activity. Taken together, our results suggest that, in humans, this enzyme might play a role in the biosynthesis of both 9-cis-retinoic acid and dihydrotestosterone.

20-Hydroxysteroid Dehydrogenases↗
PubMed2001

Structure and function of 17beta-hydroxysteroid dehydrogenase type 1 and type 2.

17beta-Hydroxysteroid dehydrogenases (17HSDs) catalyze the interconversions between high-activity 17beta-hydroxysteroids and low-activity 17-ketosteroids. Several distinct 17HSD isoenzymes have been characterized. They have unique tissue distribution patterns suggesting a specific function for each of the isoenzymes in modifying sex steroid hormone activity. The activities of 17HSDs are essential for gonadal sex steroid biosynthesis and they are also involved in the modulation of steroid hormone action in peripheral tissues. 17HSD type 1 (17HSD1) is needed for estradiol biosynthesis in ovarian granulosa cells and it is also expressed in breast tissue, thus increasing locally estradiol concentration. 17HSD type 2 (17HSD2) is another 17HSD enzyme involved in estrogen metabolism. The type 2 enzyme has an opposite activity catalyzing estradiol to estrone, thereby reducing the exposure of tissues to estrogen action. Preliminary data suggest that 17HSD2 may predominate in human non-malignant breast epithelial cells, while 17HSD type 1 activity prevails in malignant cells. Determination of the three-dimensional structure of human 17HSD1 has led to an atomic level description of the estradiol binding pocket of the enzyme and an understanding of its mechanism of action, and the molecular basis for the estrogen-specificity of the enzyme. Deprivation of an estrogen response by using specific 17HSD1 inhibitors is a tempting approach to treat estrogen-dependent breast cancer.

17-Hydroxysteroid Dehydrogenases↗
PubMed2001

Molecular cloning, modeling, and localization of rat type 10 17beta-hydroxysteroid dehydrogenase.

Rat and mouse complementary DNAs of type 10 17beta-hydroxysteroid dehydrogenase were cloned and sequenced. The mouse cDNA clone's sequence corrected the previously published nucleotide and amino acid sequence of mouse endoplasmic reticulum-associated beta-amyloid-binding protein. A subunit of the rat enzyme consists of 261 amino acid residues with a calculated molecular mass of 27250 Da. Compared with its human counterpart, rat 17betaHSD type 10 shows 88% identity. Mouse 17betaHSD type 10 is composed of 261 amino acid residues with a calculated molecular mass of 27274 Da. There is 95% identity between the two rodent enzymes. A stereostructure model of rat 17betaHSD type 10 was constructed based on its amino acid sequence. Similar to human type 10 17betaHSD, the rodent enzymes also displayed relatively higher 3alphaHSD activity than 17betaHSD activity. Intracellular localization of rat 17betaHSD type 10 has been determined by subcellular fractionation and confocal microscopy studies. The results unequivocally establish that this is a nuclear gene-encoded mitochondrial enzyme, and that this 17betaHSD is not associated with the endoplasmic reticulum. The unique location distinguishes type 10 from other types of 17beta-hydroxysteroid dehydrogenases.

17-Hydroxysteroid Dehydrogenases↗
PubMed2001

17beta-hydroxysteroid dehydrogenase type 7--an ancient 3-ketosteroid reductase of cholesterogenesis.

17beta-hydroxysteroid dehydrogenase type 7 (17beta-HSD7) is a novel estrogenic hydroxysteroid dehydrogenase from mammals. We modeled the three-dimensional structure of human 17beta-HSD7, analyzed the phylogeny of 17beta-HSD7 homologues and determined its expression pattern by in silico Northern blotting. Predominant expression is found not only in reproductive tissues (breast, ovary, placenta) but also in liver and developing brain, principal sites of cholesterol synthesis. The substrate binding pocket is opening towards a conserved membrane-associated helix, which is indicative for a conversion of a membrane component. 17beta-HSD7 shows significant homology to a yeast 3-ketosteroid reductase (ERG27) involved in ergosterol biosynthesis. Our results lead to the conclusion that 17beta-HSD7 is not only involved in estradiol production but plays another (and possibly more important) role as a 3-ketosteroid reductase in cholesterogenesis. This agrees with the striking absence of 17beta-HSD7 homologues in the complete genomes of Drosophila and C. elegans, which are both auxotrophic for cholesterol.

17-Hydroxysteroid Dehydrogenases↗
PubMed2001

Phytoestrogens inhibit human 17beta-hydroxysteroid dehydrogenase type 5.

The 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5) is involved in estrogen and androgen metabolism. In our study we tested the influence of environmental hormones, such as phytoestrogens (flavonoids, coumarins, coumestans), on reductive and oxidative 17beta-HSD activity of the human 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5). These dietary substances were shown to be potent inhibitors of aromatase, different 17beta-HSDs and seem to play an important role in delay of development of hormone dependent cancers. Our studies show that reductive and oxidative activity of the enzyme are inhibited by many dietary compounds, especially zearalenone, coumestrol, quercetin and biochanin A. Among the group of flavones inhibitor potency is growing with increasing number of hydroxylations. We suggest that these substances are bound to the hydrophilic cofactor-binding pocket of the enzyme. An interesting inhibition pattern is observed for 18beta-glycyrrhetinic acid, which has no influence on the oxidative but only on the reductive reaction. This indicates that this substrate binds to pH- and cofactor-depending sites at the active center of the enzyme.

17-Hydroxysteroid Dehydrogenases↗
PubMed1997

Involvement of a 3beta-hydroxysteroid dehydrogenase activity in ecdysteroid biosynthesis.

Ecdysteroid biosynthesis was analyzed in vitro using dissociated Y-organ cells from the shore crab Carcinus maenas. 3-Dehydroecdysone (3DE) was detected as a minor secretory product, in addition to the formerly identified end-products 25-deoxyecdysone and ecdysone (E). In conversion studies, 3DE was formed from tritiated 5beta-ketodiol (2,22,25-trideoxyecdysone), 2,22-deoxyecdysone and 2-deoxyecdysone but not from E. Further experiments were performed in order to understand the interconversions between 3-oxo and 3beta-OH compounds in the crab Y-organ. The enzyme involved in 3beta-dehydrogenation was not ecdysone oxidase, a soluble enzyme found in peripheral tissues of many arthropods but it presented strong similarities with 3beta-hydroxysteroid dehydrogenase enzymes from vertebrates: it was membrane-bound and NAD+-dependent. Moreover, a NADH-dependent 3beta-reduction of several 3-oxo-ecdysteroids was obtained using the same microsomal fraction (100,000 x g pellet) of Y-organs, indicating that the reaction might be reversible. As this activity was specific of molting glands, we hypothesize that there is at least one 3beta-hydroxysteroid dehydrogenase enzyme involved in the biosynthetic pathway of ecdysteroids.

3-Hydroxysteroid Dehydrogenases↗
PubMed1999

Minoxidil increases 17 beta-hydroxysteroid dehydrogenase and 5 alpha-reductase activity of cultured human dermal papilla cells from balding scalp.

Minoxidil is known to induce hair growth in male pattern baldness, for which development androgen plays a central role. We studied the effect of minoxidil on testosterone metabolism by cultured dermal papilla cells from balding or nonbalding scalp and dermal fibroblasts. In all three groups, 17beta-hydroxysteroid dehydrogenase activity was much higher than 5alpha-reductase activity. Minoxidil increased 17beta-hydroxysteroid dehydrogenase activity by nearly 40% (P < 0.001) in dermal papilla cells of balding scalp, whereas the effect was less marked in dermal papilla cells from nonbalding scalp and dermal fibroblasts. 5alpha-Reductase activity was also slightly increased by minoxidil in dermal papilla cells from balding scalp. Again, the effect on 5alpha-reductase activity was insignificant in the other two groups of cells. Whether such modification of testosterone metabolism in dermal papilla cells of balding scalp by minoxidil is related to its therapeutic effect remains unknown.

17-Hydroxysteroid Dehydrogenases↗