Dihydrotestosterone Receptor Research Articles

DHT and E2 synthesis-related proteins and receptors expression in male yak skin during different hair follicle stages

Dihydrotestosterone (DHT) and 17β-estradiol (E2) are sex hormones that regulate human hair follicle (HF) growth and are produced by peripheral reduction and aromatization of testosterone. However, the expression patterns of DHT and E2 synthesis-related proteins and their receptors in male yak skin during different HF stages (telogen, anagen, and catagen) are unknown. In this study, we found that both 5α-red and androgen receptor (AR) were expressed in epithelial cells and AR was expressed in the dermal papilla. Additionally, the transcription level of 5α-red1 at different HF stages was significantly higher than that of 5α-red2 mRNA at the same stage; 5α-red1 and 5α-red2 proteins peaked during the anagen and telogen periods of HF, respectively. However, AR protein was only expressed in the skin during the anagen phase of HF. Aromatase and estrogen receptors (ERα and ERβ) were expressed in cutaneous epithelial cells, whereas ERα and ERβ were expressed in the dermal papilla; the transcription level of ERα in HFs at each stage was much higher than that of ERβ. From the catagen to telogen phase, aromatase protein expression was down-regulated, while ERα protein expression was up-regulated. Based on our results, we speculate that 5α-red1 is essential for the synthesis of DHT in male yak skin epithelial cells and promotes the growth of HFs through AR. E2 synthesized by male yak skin epithelial cells may inhibit the growth of male yak skin HFs by ERα. These results provide a foundation for further study on the mechanism of hormone-regulated male yak skin HFs.

Dihydrotestosterone induces p27 degradation via direct binding with SKP2 in ovarian and breast cancer

The effect of androgens on the prevention or promotion of cell cycle progression in ovarian and breast cancer is controversial. This effect determines the basic rules of how to treat postmenopausal patients properly after surgery. In the present study, we investigated the effects of different androgens, namely dihydrotestosterone (DHT), testosterone and dehydroepiandrosterone (DHEA) in MCF-7 breast cancer and OVCAR-3 ovarian cancer cells. We found that DHT could down-regulate p27, but not p21, within 4 h. Further studies proved that DHT induced p27 degradation through the ubiquitin-proteasome proteolytic pathway. Inhibition of the androgen receptor and of phosphorylation did not hamper the degradation. However, proteolysis inhibitors effectively antagonized the DHT-induced p27 degradation. Knockdown of the S-phase kinase-associated protein 2 (SKP2), rather than of the Kip1 ubiquitination promoting complex 1 (KPC1), also prevented p27 down-regulation. DHT led to the direct binding of p27 to SKP2 independent of the phosphorylation status. Collectively, DHT, but not the other examined androgens regulated the degradation of p27 in MCF-7 and OVCAR-3 cells. Furthermore, SKP2 was shown to act as a DHT receptor.

AR (androgen receptor (dihydrotestosterone receptor; testicular feminization; spinal and bulbar muscular atrophy; Kennedy disease))

Review on AR (androgen receptor (dihydrotestosterone receptor; testicular feminization; spinal and bulbar muscular atrophy; Kennedy disease)), with data on DNA, on the protein encoded, and where the gene is implicated.

The regulation of HSL and LPL expression by DHT and flutamide in human subcutaneous adipose tissue

Clinical observations suggest a role for testosterone in the accumulation of central adiposity and with an associated increased risk of disease. To date, no human study has analysed the role of dihydrotestosterone (DHT) on adipose tissue mass regulation in vitro. This study investigated the role of DHT and androgen receptors (AR) in the regulation of lipolysis and lipogenesis by examining the key enzymes hormone sensitive lipase (HSL) and lipoprotein lipase (LPL) respectively. Isolated abdominal subcutaneous adipocytes (Scad) (n = 15) were treated with either DHT (10(-7)-10(-9) m), an antiandrogen, flutamide (FLT: 10(-7)-10(-9) m) or a combination of DHT (10(-7)-10(-9) m) with FLT (10(-8) m). Relative protein expression of HSL, LPL and AR was determined. In Scad, DHT inhibited HSL expression maximally at 10(-9) m (0.7 +/- 0.4**; p < 0.01**) compared with control (control: 1.0 +/- (s.e.m.) 0.0), whereas LPL protein expression was stimulated at DHT10(-9) m (2.22 +/- 0.48*; p < 0.05*). Glycerol release assay results correlated with HSL expression data. LPL expression was reduced at all doses with combinations of DHT + FLT compared with DHT alone. Androgen receptor expression studies showed an inverse correlation with DHT, whereas DHT + FLT reduced AR expression. These studies indicate that DHT may alter HSL and LPL expression, whereas only LPL expression appears mediated by AR. These findings suggest a physiological role for DHT in the control of adipose tissue mass in women, and indicate that androgens may also play an important role in regulating lipid metabolism.

Endocrine and adrenergic pharmacological intervention in diseases of the prostate.

The physiology of the male urogenital apparatus and reproductive function is critically dependent on a healthy prostate. Since growth and function of the prostate are governed by androgens, endocrine interventions with the synthesis, uptake, or metabolism of these hormones are major pharmacological/therapeutic strategies in prostate diseases, e.g. cancer of the prostate (CaP) and benign prostatic hyperplasia (BPH). Pharmacological interference with androgen metabolism is associated with inevitable adverse effects. Therefore, it is important that such treatment be exercised with caution and weighed against its potential effects on the symptoms and outcome of the disease. α-Adrenergic blockade is an alternative treatment in BPH since α1-adrenoceptors are localized in the prostate stromal structures and considered to mediate an increased infravesical obstruction. Cancer of the prostate (CaP) is the most common cancer in the western male population with the highest incidence in Nordic countries (115/100 000) and in the USA, particularly in black Americans [1]. The incidence increases with age. About 30 to 35% of Swedish men at the age of 50 years have microscopic adenocarcinoma whereas the corresponding figure is more than 50% at the age of 80 years [2]. It has been estimated that about 7% of Swedish men will develop clinical CaP before the age of 75 years [2]. The other major disease of the prostate is BPH which is a histopathological diagnosis leading to benign prostatic enlargement and finally to bladder outlet obstruction. For the sake of simplicity, the clinical syndrome will be referred to as BPH in the following review. BPH is symptomatic in more than 40% of the ageing male population [3]. Shown in Table 1 are some prevalence numbers for CaP and BPH. Table 1 Prevalence of diseases of the prostate in relation to age. Given this situation, it is not surprising that diseases of the prostate have attracted considerable interest from the scientific community and the public. Compared with men from western societies, oriental men like the Japanese have a low incidence of CaP [4]. The higher incidence in oriental men living in the US compared with men in their native countries indicates that environmental as well as genetic factors influence the prevalence of this disease in the population. For BPH, development of effective pharmacological intervention therapies as well as new physical treatment modalities have challenged the classical surgical approaches to cure the disease. Even though the efficacy of drugs may be limited compared to surgical and physical means of treatment, they are often preferred because of the much lower complication risks [5]. A comparison of pharmacological and non-pharmacological treatments in terms of efficacy and complication risks is depicted in Figure 1. Figure 1 Efficacy of treatment methods for BPH in relation to risk of complications. Arbitrary dimensions on Y- and X-axes. TUMT=transurethral microwave treatment; TUNA=transurethral needle ablation; TUIP=transurethral incision of the prostate; TURP=transurethral ... The scope of this article is to describe the current possibilities and ideas for pharmacological intervention strategies, and to discuss their limitations and basis for further development of more advanced treatment programs.

Endocrine and adrenergic pharmacological intervention in diseasesof the prostate

Endocrine and adrenergic pharmacological intervention in diseasesof the prostate

Androgen induction of steroid 5 alpha-reductase may be mediated via insulin-like growth factor-I.

The action of added insulin-like growth factor-I (IGF-I) and dihydrotestosterone (DHT) on steroid 5 alpha-reductase (5 alpha R) activity was studied using primary cultures of rat or human scrotal skin fibroblasts. Agents were added to cultured cells (2 x 10(5) cells) for 2 days, and enzyme activity was measured by the percent conversion of [3H] testosterone to DHT over a 4-h period in the absence of fetal calf serum or other growth factors. DHT, but not testosterone, at 10(-7) M significantly increased 5 alpha R activity (rat, 1.5 +/- 0.3% to 3.0 +/- 0.4%; human, 7.6 +/- 1.7% to 11.4 +/- 2.9%; P < 0.01). IGF-I (10(-9)-6.4 x 10(-9) M), but not IGF-II (10(-9)-10(-8) M) or insulin (10(-9)-10(-7) M), increased enzyme activity in a dose-related fashion [i.e. 1.5 +/- 0.5 to 10 +/- 2 in rat and 6.0 +/- 1.1 to 9.8 +/- 1.6% (P < 0.01) in human cells]. No change in cell numbers was observed in any experiment. Since the effect of IGF-I was about 100 times that of androgen, we studied the possibility that androgen induction of the enzyme activity could be via IGF-I production. Addition of a monoclonal antibody against IGF-I significantly reduced the effect of DHT, and simultaneous addition of a specific IGF-I receptor antibody blocked the expected induction of 5 alpha R activity (control, 4.9 +/- 0.5; DHT, 8.0 +/- 1.9; DHT plus IGF-I receptor antibody, 3.7 +/- 0.4%). No effect on 3 alpha-reduction of [3H]DHT to 3 alpha-androstanediol was detected in separate experiments. These studies indicate that IGF-I may be an important regulator of skin 5 alpha R activity and, thus, may influence DHT formation. The previously known androgen induction of this peripheral steroidogenic enzyme may be via paracrine/autocrine production of an IGF-I-type growth factor.

Phenotypic Variation in Patients with Partial Androgen Insensitivity Syndrome

We report the cases of two infants with ambiguous genitalia who were found to have partial androgen insensitivity syndrome by androgen receptor studies conducted on cells obtained from a genital skin biopsy. Both patients had been born at full term and appeared normal except for their external genitalia. One patient had a hooded phallus and scrotal hypospadias. The testes were found in the inguinal canals. The genitalia of the other patient appeared to be female, but testes were found in the labia majora. At genitography, the urogenital sinus was observed to be short and the vaginal cavity of normal size. The serum testosterone level of the first patient was significantly elevated. Androgen receptors were measured in skin with fibroblasts cultured from the prepuce. The maximum binding capacity of the dihydrotestosterone receptor for each patient was 263 and 340 fmol/mg DNA, respectively (normal mean±SD, 722±225 fmol/mg DNA). The dihydrotestosterone binding affinity of the receptor was significantly lower than normal, (Kd: mean±SD, 0.71±0.17 nM), i. e., 1.14 nM in the first patient and 1.26 nM in the other. These findings raise the question of the mechanism of the different degrees of masculinization of the external genitalia with a similar abnormality in the androgen receptor.

Immortalization of Human Adult Normal Prostatic Epithelial Cells by Liposomes Containing Large T-SV40 Gene

Simian virus SV40 has been widely used to immortalize epithelial cells of mammalian origin. We report here, for the first time to our knowledge, the immortalization of normal adult prostatic epithelial cells in culture by transfection of a plasmid containing SV40 genome with a defective replication origin (SV40 ori-) encapsulated into liposomes. These cells (PNT1) have now been cultured for more than 12 months, and shown to contain the SV40 genome. They express large T protein, present the phenotype of differentiated luminal prostatic cells (positive with antibodies to cytokeratin 18, 19, weakly positive for prostatic acid phosphatase and prostatic specific antigen, negative with anticytokeratin 14 and KL2 antibody). PNT1 cells contain high affinity receptors for dihydrotestosterone. These cells provide a useful tool to study the biology and the pathology of adult prostatic epithelial cells, specially to understand the steps leading to prostatic transformation.

Male pseudohermaphroditism due to Leydig cell agenesia and absence of testicular LH receptors

The aim of our study was to establish the definitive diagnosis in an adult patient with male pseudohermaphroditism in whom testicular feminization syndrome had been suspected at the age of 8, based on genetic, clinical and pathological studies. Hypothalamo-hypophysio-testicular function was assessed in vivo. Androgen mechanism of action and testicular gonadotrophin binding were studied in vitro. At the age of 33 the phenotype was almost completely feminine except for slight clitoral enlargement and posterior labial fusion. Internal genital duct derivatives were masculine except for a short vagina. Both testes were cryptorchid. LH and FSH were determined pre- and post-gonadectomy. Progesterone, 17-OH-progesterone, androstenedione, dehydroepiandrosterone testosterone (T) and oestradiol were determined basally in peripheral and spermatic blood post-hCG stimulation, and in peripheral blood after orchidectomy. Dihydrotestosterone (DHT) receptors and 5 alpha-reductase activity were determined in genital skin fibroblasts. Receptors for LH and FSH were determined in membrane preparations from both testes. LH was high (31 IU/l) and FSH (8 IU/ml) normal. T or steroid precursors were detected basally or after hCG stimulation in peripheral blood showing absence of testicular production. Spermatic venous blood steroid concentrations were consistent with slight T production, in accordance with testis histology which showed few Leydig-like cells among fibroblasts in the interstitial space. DHT specific binding capacity and affinity and 5 alpha-reductase activity were normal in genital skin fibroblasts. Gonadotrophin binding studies in testicular membranes confirmed the absence of LH specific binding, whereas FSH binding was higher than normal when expressed per mg of protein (27.0 vs 9.4 +/- 0.6 fmol/mg protein in controls), and lower than normal in both testes since patient's testicular weights were abnormally low. The patient was considered to have an almost complete form of Leydig cell agenesia/hypoplasia in which absence of specific LH binding correlated with total absence of differentiated Leydig cells and insensitivity of undifferentiated interstitial cells to LH stimulation.

Clinical and Experimental Studies of Benign Prostatic Hyperplasia

The canine prostate appears to be a suitable model for investigating many aspects of abnormal prostate growth related to BPH. This model has indicated that BPH is a complex pathologic process that varies with age and produces a gland that is composed of a mixture of glandular, cystic, and stromal hyperplasia juxtapositioned with foci of atrophy. Canine BPH first occurs very early in life as a glandular hyperplasia before the onset of more complex BPH. As the prostate increases in size with age, the tissue dihydrotestosterone content falls, as does the secretory capacity of the gland. The fall in glandular dihydrotestosterone content is counterbalanced by a concomitant increase in the metabolism of androgens toward dihydrotestosterone and an increase in nuclear androgen receptors. As the prostate ages, it thus becomes more sensitive to androgens, which are required for maintaining the abnormal size of the gland. Established BPH can be maintained in the absence of the testes in the presence of normal testosterone levels, and it appears that the abnormal growth is primarily attributable to an inherent change that has occurred in the aged prostate. In the dog and man, both the normal prostate and BPH are rich in growth factors and dihydrotestosterone receptor in the nucleus, yet mitotic cells are rare. Established BPH is not growing rapidly; the abnormal size of the aged prostate is maintained, not by an increase in the rate of cell replication, but rather by an apparent decrease in the rate of cell death. It appears that a combination of estrogens and 5 alpha-reduced androgens can cause this decrease in the rate of cell death and replication and that this imbalance can produce abnormal cell accumulation and an experimental prostatic hyperplasia. Besides affecting cell death and replication, estradiol has a marked effect in stimulating the stroma and collagen synthesis. Current investigations are focusing on determining the distribution of stem cells for both the epithelial and the stromal elements of the prostate, how these stem cells are recruited to form transiently proliferating cells, and how they mature and subsequently are programmed for cell death. It is believed that steroid imprinting in the neonatal and prepubertal period may be of great importance in determining the ultimate growth of the prostate. Preliminary attempts to control abnormal canine prostate growth by forcing maturation with retinoic acid, or by interfering with growth factors through the use of suramin, have not proved effective; only androgen ablation is. Important leads in the search for the etiology and control of BPH can be studied in the canine model. These concepts must ultimately be tested and confirmed for human BPH in well-controlled clinical investigations.

Influence of cell culture conditions on aromatase activity in human genital skin fibroblasts.

Because the measurement of aromatase activity in cultured human genital skin fibroblasts has been proposed as a means of studying estrogen production in men, we investigated the influence of culture conditions on aromatase activity. Genital skin fibroblasts were seeded onto culture plates at a density of 1 X 10(6) cells/plate and aromatase activity was determined over a 1-mo. period. Enzyme activity rose slowly over the first 14 d but then rose rapidly to a 10-fold higher plateau by Day 28. The rise in aromatase activity was similar whether activity was normalized for protein or for DNA content. When cells were seeded at the usual density of 1 X 10(6) or at 0.25 X 10(6) cells/plate, aromatase activity was consistently lower during the first 2 wk in cells plated at lower density, but thereafter the levels of enzyme activity in the two groups converged. In cells plated at the lower density, the lower activity observed in the first 2 wk was associated with a lower Vmax. Preincubation of cells plated at one density with conditioned medium from cells plated at the other density did not change the relative levels of activity in the two groups. By contrast, dihydrotestosterone (DHT) receptor binding and 5 alpha-reductase activity were similar at all time points, despite differences in plating density. In additional experiments, the culture medium was replaced daily rather than every 3rd d, and aromatase activity was assayed on Day 7. In cells fed daily, DNA and protein content were twice that of cells fed every 3rd d. By contrast, aromatase activity declined to 30% of that in the latter group. DHT and dexamethasone receptor binding and 5 alpha-reductase activity were similar in the two groups. In summary, factors such as plating density, culture density, and frequency of media replacement dramatically influence aromatase activity in cultured human genital skin fibroblasts. Therefore, the interpretation of aromatase activity data obtained from cultured cells in relation to physiologic or pathologic states should be viewed with appropriate caution.

Heart contains receptors for dihydrotestosterone but not testosterone: Possible role in the sex differential in coronary heart disease

The sex differential in coronary heart disease is well documented but poorly understood. Previous studies have demonstrated receptors for dihydrotestosterone (DHT) in the myocardium and smooth muscle cells of arteries from a number of species. In this autoradiographic study, we further investigated and characterized the in vivo uptake and retention of the androgen binding in the male baboon. Adult castrated male baboons were injected with 1 micrograms/kg bw 3H-testosterone; 1 hr after the injection, the animals were rapidly exsanguinated while under anesthesia. The heart and arterial system were removed and processed for autoradiography. As a negative control, one animal received both 3H-testosterone and 100-fold unlabeled testosterone. For positive controls, the pituitary gland, prostate, seminal vesicles, and other tissues were also removed and processed for autoradiography. In contrast to our previous finding with 3H-DHT, no nuclear uptake and retention of 3H-steroid was found in any of the cells in either the heart or the arterial system. In the positive control tissues, pituitary gland, prostate, seminal vesicles, and others, a very distinct nuclear uptake and retention of 3H-steroid was observed, which was completely inhibited by the simultaneous injection of 100-fold unlabeled testosterone. In the binding study, Scatchard analysis of the cytosol prepared from a 17-year-old female baboon demonstrated levels of androgen receptor (as determined by the use of radiolabeled R1881) comparable to that found in young adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Megestrol acetate: clinical experience

The use of megestrol acetate in treatment of malignancy (endometrial carcinoma, ovarian cancer, prostate cancer, breast cancer, renal cell carcinoma, malignant melanoma), endometrial hyperplasia, benign prostatic hypertrophy, contraception, anorexia, cachexia and weight loss is reviewed, concluding with a toxicity profile. Megestrol acetate was introduced in 1971 for treatment of endometrial carcinoma. Megestrol acetate is probably effective in proportion to the number of cytoplasmic progesterone receptors, but it has not been tested in a Phase III trial. For ovarian cancer it has been reported to be effective in 1 trail at doses of 800 mg/day. Prostate cancer, although difficult to assess, responds to megestrol acetate at doses of 120 mg/day because of its suppression of gonadotropins, its inhibition of 5alpha-reductase and its binding to the dihydrotestosterone receptor. Megestrol acetate permits a lower dose of diethylstilbestrol, and thus lower toxicity. There is apparently a dose-response between megestrol acetate and breast cancer, along with a response dependent on the number and type of estrogen and progestin receptors. Responses are better in postmenopausal women, and additive with other agents such as tamoxifen and mitomycin C. The medium duration of effect is 6-8 months. It has no effect on renal cancer or malignant melanoma. Megestrol acetate can be considered as an effective medical alternative to surgery for endometrial hyperplasia or benign prostatic hypertrophy. As a contraceptive in inhibits sperm transport rather than ovulation, but also causes irregular bleeding. Megestrol acetate has few side effects, and has the advantage of stimulating appetite and weight gain, a benefit in cancer patients.

Diagnosis of Peripheral Androgen Insensitivity in A Male Infant Excretion Analysis

The hypothesis of peripheral androgen insensitivity (AIS) was examined in a boy with congenital growth hormone deficiency associated with micropenis and cryptorchidism by steroid excretion analyses compared with dihydrotestosterone (DHT) receptor analyses of foreskin biopsy homogenate. Urinary T metabolite 3 alpha,17 beta-dihydroxy-5 beta-androstane (3 beta-diol) was below the limit of detection (capillary gas chromatography) at age 1 year, but on several occasions (n = 7) normal basal values were found at age 3 years (patient: 78.9 +/- 25.4 micrograms/24 h, M +/- SD; controls, n = 15: 100.5 +/- 50.2). Normal basal- and hCG-induced excretion was noted for 3 alpha,17 beta-dihydroxy-5 alpha-androstane (3 alpha-diol) at age 1 and 3 years, respectively. Additionally, basal 3 alpha-diol excretion (n = 7) at age 3 years was 66.7 +/- 21.1 micrograms/24 h, M +/- SD; controls (n = 15) 75.8 +/- 50.4. Analysis of urinary androgens might be an alternative, noninvasive procedure for the diagnosis of peripheral AIS.

Androgen Receptor Levels and 5α-Reductase Activities in Preputial Skin and Chordee Tissue of Boys with Isolated Hypospadias

The cause of hypospadias in the majority of patients is unknown. We examined the hypothesis that hypospadias might be explained by androgen receptor abnormalities in the atretic spongiosal tissue commonly known as chordee. We studied 10 patients with relatively severe hypospadias but with a predominantly male phenotype and no readily ascertained explanation for the defect, including no evidence of an abnormality in testosterone biosynthesis. Eight subjects had midshaft hypospadias and 2 had a penoscrotal meatus. All 10 patients had severe chordee. Serum concentrations of testosterone, and luteinizing and follicle-stimulating hormones were measured before human chorionic gonadotropin stimulation and a serum testosterone level was determined 24 hours after the last dose of a 5-day human chorionic gonadotropin stimulation (3,000 units per M.2 per day).Androgen receptor content and binding affinity were assayed in fibroblasts cultured from preputial skin and chordee tissue of patients and foreskin from normal male neonates. With the endogenous ligand dihydrotestosterone the mean number (maximum binding capacity) of androgen receptors was 1,013 fmol. per mg. deoxyribonucleic acid in preputial skin and 833 fmol. per mg. deoxyribonucleic acid in chordee tissue of patients, and 627 fmol. per mg. deoxyribonucleic acid in the foreskin of controls. With the nonmetabolizable, synthetic androgen methyltrienolone (R1881) the mean maximum binding capacity was 1,004, 722 and 758 fmol. per mg. deoxyribonucleic acid, respectively. Dihydrotestosterone receptor affinity (dissociation constant) was similar in preputial skin (0.20nM.) and chordee tissue (0.21nM.) from patients, and foreskin (0.29nM.) from controls. Androgen receptor binding affinity of R1881 also was similar (0.30, 0.24 and 0.21nM., respectively). Furthermore, the 5 α-reductase activity of preputial skin and chordee tissue of patients with hypospadias was similar to that of foreskin from normal neonates.In conclusion, isolated hypospadias in these subjects was not associated with androgen insensitivity of the spongiosal tissues on the basis of either decreased androgen receptor binding affinity, receptor number or conversion of testosterone to dihydrotestosterone.

Effects of exogenous melatonin prior to the breeding season on testis weight and epididymal androgen receptors in rams

Rams were randomly assigned to an experiment that evaluated effects of treatment (2.5 mg melatonin/d for 45 d vs control; MEL vs CON) in mid-May through June on testis weight and concentration of epididymal androgen receptor in July or September (Sept). Mean testis weight of MEL and CON rams was not different in July (332 vs 283 g), but in Sept was less (P<.05) for MEL rams than CON rams (268 vs 382 g). Testis weight of MEL rams was less (P<.05) in Sept than in July. Caput, corpus and cauda epididymal tissues were used to prepare extracts which were analyzed for concentration of dihydrotestosterone (DHT) receptor using a new standard curve method. A standard extract was characterized using four independent 8-point Scatchard analyses and found to contain 6.0 fmol DHT receptor/mg wet tissue (Ka = 3.5 × 10 8M −1); this extract was used to establish standard curves for assays of unknown samples. Data on concentration of DHT receptors measured by Scatchard analysis and the standard curve method were highly correlated (r = 0.99; P<.01; n = 8). Concentrations of DHT receptor were not affected by treatment, month of castration, or their interaction. However, for data pooled across treatment and month, concentration (fmol/mg protein) of DHT receptor was greater (P<.05) in caput or corpus (125 or 122) than in cauda (92) epididymidis. The regional distribution of epididymal DHT receptors in this study confirmed our previous findings. These results revealed that the melatonin treatment used in this study did not increase testis weight by early July, but caused premature decline in testis weight by Sept. However, the melatonin treatment did not influence concentration of DHT receptor in the epididymis.

The subcellular defects in the androgen insensitivity syndrome.

The androgen insensitivity syndrome (AIS) was studied with consideration of the complexity of mechanisms involved on the intracellular level: testosterone (T) and dihydrotestosterone (DHT) receptors and the androgen-5 alpha-reductase (A5R). Five children with "normal" female external genitalia (group A) and three patients with variable forms of ambiguity (group B), ages 1 to 18 years, were studied. Tissue specimens from genital skin were analysed for the Kd- and N max-values of the cytosolic and nuclear T- and DHT-receptors, as well as for the Km- and Vmax-data of the tissue specific A5R. The enzyme analyses were performed with a kinetic method. Results show that patients from group A mainly lack action of the nuclear DHT receptor, combined with reduces binding capacity in the cytosol. T binding was poor in both, cytosolic and nuclear fractions, respectively. Results of group B proved to be more inhomogeneous, ranging from total absence of a DHT receptor to normal binding capacities in the nuclear fractions, accompanied by decreased cytosolic N max values for that ligand. T binding was poor in all patients of group B in the cytosolic and nuclear fractions, respectively. A5R was qualitatively normal in all patients examined, except one, but decreased enzyme activities could be observed in a wide range. In summary, the study confirms the complex mechanisms, presenting as AIS clinically. Moreover a close relationship between abnormalities of androgen receptor function and changes in A5R activity could be evaluated, thus confirming the recent theories about intracellular androgen action.

162 ANDROGEN RECEPTORS IN “TRANSITORY ANDROGEN INSENSITIVITY SYNDROME” OF THE NEWBORN

Androgen receptor analyses of scrotal tissue from a boy with congenital growth hormone (GH) deficiency associated with micropenis, done at agel and 3yrs, revealed a decreased cytosolic binding for testosterone(T) and dihydrotestosterone(DHT), compared to controls or similar age* (patient vs controls, age 1 and 3yrs, respectively; Nmax for T: 28 and 30 vs 150±30 and 130±28 fmol/mg protein, M±SD; Nmax for DHT: 30 and 114 vs 205±98 and 480±135). Nuclear T receptor was not detectable at age1, but showed abnormal high binding at age 3yrs (90 vs 22±5). Nuclear DHT receptor was within normal limits at age1 and 3yrs (117 and 180'vs 91±28 and 181±26). Tissue specific 5α reductase (ASR) activity was found to be 3.2 pmol/h/mg protein (age1) and 16.1 (age3) (controls*: 15.8±1.9, M±SD). HCG stimulation resulted in a 3-fold rise of plasma T (0.15 to 0.46 ng/ml) at age1 and a 6-fold rise (0.18 to 1.09) at age 3yrs, without change of DHT. Strechted penile length was 1.1 cm ( 25.centile) at age 3. The receptor and ASR data indicate a catch-up growth and normalization of the external genital status. We postulate a “transitory androgen insensitivity syndrome” in this patient. *K Herkner et al. J steroid Biochem.24 (1986) 239-243

Inhibition of androgen receptor binding by natural and synthetic steroids in cultured human genital skin fibroblasts

The ability of various natural and synthetic steroids (some of which are widely used in clinical practice) to compete with dihydrotestosterone receptor binding in human genital skin fibroblasts was studied. Binding was assessed in fibroblast monolayers after incubation for 1 h at 37 degrees C with 2 nM 3H-dihydrotestosterone in the presence or absence of increasing concentrations of the steroid to be tested. Inhibition constants (Ki) were determined as the concentration of competitor-required for 50% inhibition of 3H-dihydrotestosterone binding. In addition, relative binding activity (RBA) of each test compound was calculated. Each competitor was tested in at least two different cell strains. The concentrations of unlabeled methyltrienolone (a synthetic nonmetabolizable androgen) and dihydrotestosterone for 50% inhibition of 3H-dihydrotestosterone binding were in the same order of magnitude, namely, 2 nM (2.2 respectively, 2.4 nM), whereas the affinity of testosterone was approximately one-fifth that of dihydrotestosterone. Other potent competitors for dihydrotestosterone binding were three progestins (norgestrel, gestoden, and medroxyprogesterone acetate) which have Ki values similar to testosterone. An order of magnitude lower Ki values (around 10(-7) M) were found for the androgen 17 alpha-propylmesterolone, the antiandrogen cyproterone acetate, and the progestin norethisterone acetate. Binding affinities of all other steroids to the androgen receptor were markedly lower and showed the following order of potency: estrogens (estradiol, ethinyl estradiol, diethylstilbestrol) greater than glucocorticoids as well as aromatase inhibitors and potassium canrenoate.(ABSTRACT TRUNCATED AT 250 WORDS)