The 5alpha-reductase type 1, but not type 2, gene is expressed in anagen hairs plucked from the vertex area of the scalp of hirsute women and normal individuals

Hirsutism, Normal Androgens and Diagnosis of PCOS

Hirsutism is defined as the presence of terminal hair with male pattern distribution in women. While in the general population, hirsutism affects around 4-11% of women, it is the main manifestation of hyperandrogenism in women with polycystic ovary syndrome (PCOS), with a prevalence estimated at 65-75%. Hirsutism in PCOS is associated with both androgen excess and individual response of the pilosebaceous unit to androgens. The modified Ferriman-Gallwey (mFG) scoring system has been widely used in clinical practice to visually score excessive terminal hair, thus standardizing hirsutism evaluation and facilitating data comparison. Although a universal mFG score cutoff would be useful for comparisons, ethnic variations, as well as skin type and other factors, should be considered when evaluating hirsutism in distinct populations. In turn, androgen levels, measured by conventional techniques, have been shown to correlate poorly with the severity of hirsutism. Indeed, while most women with PCOS and hirsutism also have higher than reference values for serum androgen levels, some of them may not present with biochemical hyperandrogenism, representing a challenge to the diagnosis of PCOS. In this article, we critically review this not uncommon condition in women with PCOS presenting with hirsutism but normal androgen levels.

Discovery of Natural Steroid 5 Alpha-Reductase Inhibitors

Human steroid 5 alpha-reductases (S5αRs) and NADPH irreversibly reduce testosterone to the more potent dihydrotestosterone (DHT). S5αR inhibitors are useful treatments for DHT-dependent diseases, including benign prostatic hyperplasia, androgenic alopecia and hair growth, and acne. There are three S5αR isozymes, and there is a need for safer and more isozyme selective inhibitors than finasteride and dutasteride currently licensed. In this study, we review the methods used to screen for S5αR inhibitory activity and describe studies that characterize the ability of herbal preparations and their constituents to inhibit S5αRs. We identified enormous variations between studies in IC₅₀s for finasteride and dutasteride used as standards. Accordingly, we make several recommendations: Stable isozyme specific transfection systems need creating a standardized enzyme/microsome preparation and all three isozymes, as well as androgen receptor binding, should be tested; agreed reaction conditions, especially the substrate concentrations, and separation/quantitation method optimized for high throughput screening; systematic screening of herbal compounds and most extensive use of leads to develop more potent and isozyme specific inhibitors.

Plucked human hair shafts and biomolecular medical research

The hair follicle is a skin integument at the boundary between an organism and its immediate environment. The biological role of the human hair follicle has lost some of its ancestral importance. However, an indepth investigation of this miniorgan reveals hidden complexity with huge research potential. An essential consideration when dealing with human research is the awareness of potential harm and thus the absolute need not to harm—a rule aptly qualified by the Latin term “primum non nocere” (first do no harm). The plucked hair shaft offers such advantages. The use of stem cells found in hair follicles cells is gaining momentum in the field of regenerative medicine. Furthermore, current diagnostic and clinical applications of plucked hair follicles include their use as autologous and/or three-dimensional epidermal equivalents, together with their utilization as surrogate tissue in pharmacokinetic and pharmacodynamics studies. Consequently, the use of noninvasive diagnostic procedures on hair follicle shafts, posing as a surrogate molecular model for internal organs in the individual patient for a spectrum of human disease conditions, can possibly become a reality in the near future.

Association of genetic variants in the two isoforms of 5α-reductase, SRD5A1 and SRD5A2, in lean patients with polycystic ovary syndrome

OBJECTIVE

Given its role in converting testosterone to dihydrotestosterone and cortisol to dihydrocortisol, 5α-reductase may be important in the pathophysiology of the polycystic ovary syndrome (PCOS). Increased activity of this enzyme has already been demonstrated in ovaries of affected women, and might be caused by genetic alterations. The aim of this study was to analyze representative genetic variants of both isoforms of 5α-reductase with regard to PCOS parameters in lean and obese women.

STUDY DESIGN

We analyzed one single nucleotide polymorphism (SNP) (rs523349) of the isoform 2 (SRD5A2) and one haplotype of the isoform 1 (SRD5A1), consisting of the two SNPs rs39848 and rs3797179, in 249 women with PCOS and 226 healthy women using a 5'-exonuclease-assay. The genotypes were associated with anthropometric, metabolic and hormonal as well as functional tests in these women.

RESULTS

In the investigated haplotype of SRD5A1, the TA variant was associated with an increased frequency of PCOS (P=0.022) and an increased Ferriman-Gallwey Score (hirsutism) (P=0.016) in women with normal weight. The G allele at the examined position of the SRD5A2 showed a decreased frequency of PCOS (P=0.03) in women with normal weight.

CONCLUSION

One of the keys in the development of the PCOS is hyperandrogenism, which might be caused by an increased 5α-reductase activity, as it is often seen in obesity. This mechanism might therefore be of importance in lean PCOS patients and contribute to the clinical findings.

Variants in the 5alpha-reductase type 1 and type 2 genes are associated with polycystic ovary syndrome and the severity of hirsutism in affected women

CONTEXT

Despite the importance of dihydrotestosterone in androgen action, polymorphisms in the genes for the two isoforms of 5alpha-reductase (SRD5A1 and SRD5A2) have not been evaluated as risk factors for polycystic ovary syndrome (PCOS).

OBJECTIVE

The objective of the study was to test the hypothesis that haplotypes in the SRD5A1 and SRD5A2 genes are risk factors for PCOS and the severity of hirsutism in affected women.

DESIGN

PCOS and control subjects were genotyped for seven single-nucleotide polymorphisms in SRD5A1 and eight single-nucleotide polymorphisms in SRD5A2. Haplotypes were determined and tested for association with PCOS diagnosis and component phenotypes.

SETTING

Subjects were recruited from the reproductive endocrinology clinic at the University of Alabama at Birmingham; control subjects were recruited from the general surrounding community. Genotyping took place at Cedars-Sinai Medical Center in Los Angeles.

PARTICIPANTS

A total of 287 White women with PCOS and 187 controls participated.

MAIN MEASUREMENTS

SRD5A1 and SRD5A2 genotype, quantitative hirsutism score, and hormonal and metabolic phenotypes were assessed.

RESULTS

Haplotypes within both genes were associated with PCOS risk. The Leu allele of the Val89Leu variant in SRD5A2 was associated with protection against PCOS; this allele is known to modestly reduce 5alpha-reductase activity. Haplotypes in SRD5A1 but not SRD5A2 were also associated with the degree of hirsutism in affected women.

CONCLUSIONS

This study presents genetic evidence suggesting an important role of both isoforms of 5alpha-reductase in the pathogenesis of PCOS. That only SRD5A1 haplotypes were associated with hirsutism suggests that only this isoform is important in the hair follicle.

Tissue-specific transcription profiles of sex steroid biosynthesis enzymes and the androgen receptor

17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 5alpha-reductase isoenzymes play a crucial role in the formation and metabolism of sex steroids. Not only the key androgens testosterone and dihydrotestosterone but also their precursors are potent activators of the androgen receptor and are, therefore, likely to act as determinants of male sexual differentiation and maturation in a differentially regulated way. The aim of the present study was to relatively quantify the expression of the mRNA of 17beta-HSD isoenzymes, namely, type 1, 2, 3, 4, 5, 7, and 10, together with the 5alpha-reductase type 1 and 2, and the androgen receptor in normal human males and females. RNA was isolated from peripheral blood cells of both sexes and from genital skin fibroblasts (GSFs) of two different localizations (foreskin and scrotal skin) obtained from phenotypically normal males. mRNA expression was semi-quantified by quantitative reverse-transcriptase polymerase chain reaction with the LightCycler Instrument (Roche). The examined enzymes show statistically significant differences in their transcription pattern between the blood and the GSF RNA samples. Within the GSF samples, there are also significant variations between the two examined localizations in the transcription of 17beta-HSD type 1, 2, 4, and 5 as well as for the androgen receptor. We found large interindividual variation of enzyme transcription patterns in all investigated tissues. In peripheral blood cells, no sex-specific differences were seen. We conclude that sex steroid enzymes are expressed not only in genital primary target tissues but also in peripheral blood. The expression in different target tissues may contribute to both the individual sexual and tissue-specific phenotype in humans.