Immunocytochemical localization of androgen receptor with polyclonal antibody in paraffin-embedded human tissues

Immunoexpression of androgen receptor in the nontumorous pituitary and in adenomas

Little information is available regarding androgen receptor immunoexpression (AR) in the normal and neoplastic human pituitary. Available experimental data links it to primarily gonadotroph cells. We undertook an immunohistochemical study of 41 autopsy-derived normal glands from patients of both sexes and all ages as well as 79 fully characterized pituitary adenomas of all types, the focus being upon AR expression in normal and neoplastic gonadotrophs. Nuclear AR immunoreactivity was noted in gonadotrophs and other normal adeno- and neurohypophysial cells. In addition to its presence in 74% of gonadotroph and 55% of null cell adenomas, lesser proportions of other adenoma types (adrenocorticotropic hormone 50%, prolactin 38%, growth hormone 33%) also exhibited AR immunoreactivity. No staining of thyroid-stimulating hormone adenomas was noted. The physiologic significance of our findings remains to be explored. The literature regarding AR expression in animal and human pituitaries is reviewed.

Sexual maturation modulates expression of nuclear receptor types in laser-captured single cells of the cichlid (Oreochromis niloticus) pituitary

The role of steroid/thyroid hormones in the regulation of endocrine cells at the level of the pituitary has remained unclear. Therefore, using single-cell quantitative real-time PCR, we examined absolute amounts of transcripts for nuclear receptors [estrogen receptors (ERs) alpha, beta, and gamma; androgen receptors (ARs) a and b; glucocorticoid receptors (GRs) 1, 2a, and 2b; and thyroid hormone receptors (TRs) alpha1, alpha2, and beta] in pituitary cells of immature (IM) and mature (M) male tilapia, Oreochromis niloticus. In the two reproductive stages, ACTH cells expressed only ERbeta, whereas all other pituitary cell types expressed ERalpha + beta, and a subpopulation coexpressed ARa, ARb, GR1, GR2b, and TRbeta but lacked ERgamma, GR2a, TRalpha1, and TRalpha2. IM males had high percentages of LH cells (IM 46.0% vs. M 10.0%), GH cells (IM 23.3% vs. M 7.9%), and prolactin cells (IM 68.8% vs. M 6.0%) with ERbeta, and TSH cells (IM 19.2% vs. M 0.0%) and MSH cells (IM 25.6% vs. M 0.0%) with ERalpha + TRbeta. A high percentage of FSH cells in IM males expressed ERbeta (IM 46.9% vs. M 18.8%), and FSH cells in M males showed significantly high GR1 transcripts (IM 76.0 +/- 5.0 vs. M 195.0 +/- 10.7 copies per cell; P < 0.05), suggesting that FSH cells are regulated differently in the two reproductive stages. Coexpression of ERalpha + beta in high percentages of cells of the GH family (GH, IM 43.8% vs. M 14.3%; prolactin, IM 8.3% vs. M 59.7%; somatolactin, IM 22.2% vs. M 42.2%) suggests that the expression of both ERs is important for functionality. Thus, differential coexpression of genes for nuclear receptors in subpopulations of pituitary cell types suggests multiple steroid/thyroid hormone regulatory pathways at the level of the pituitary during the two reproductive stages.

Androgenic/estrogenic balance in the male rat cerebral circulation: metabolic enzymes and sex steroid receptors

Tissues from males can be regulated by a balance of androgenic and estrogenic effects because of local metabolism of testosterone and expression of relevant steroid hormone receptors. As a critical first step to understanding sex hormone influences in the cerebral circulation of males, we investigated the presence of enzymes that metabolize testosterone to active products and their respective receptors. We found that cerebral blood vessels from male rats express 5alpha-reductase type 2 and aromatase, enzymes responsible for conversion of testosterone into dihydrotestosterone (DHT) and 17beta-estradiol, respectively. Protein levels of these enzymes, however, were not modulated by long-term in vivo hormone treatment. We also showed the presence of receptors for both androgens (AR) and estrogens (ER) from male cerebral vessels. Western blot analysis showed bands corresponding to the full-length AR (110 kDa) and ERalpha (66 kDa). Long-term in vivo treatment of orchiectomized rats with testosterone or DHT, but not estrogen, increased AR levels in cerebral vessels. In contrast, ERalpha protein levels were increased after in vivo treatment with estrogen but not testosterone. Fluorescent immunostaining revealed ERalpha, AR, and 5alpha-reductase type 2 in both the endothelial and smooth muscle layers of cerebral arteries, whereas aromatase staining was solely localized to the endothelium. Thus, cerebral vessels from males are target tissues for both androgens and estrogen. Furthermore, local metabolism of testosterone might balance opposing androgenic and estrogenic influences on cerebrovascular as well as brain function in males.

Gender differences in kidney function

Sex hormones influence the development of female (F) and male (M) specific traits and primarily affect the structure and function of gender-specific organs. Recent studies also indicated their important roles in regulating structure and/or function of nearly every tissue and organ in the mammalian body, including the kidneys, causing gender differences in a variety of characteristics. Clinical observations in humans and studies in experimental animals in vivo and in models in vitro have shown that renal structure and functions under various physiological, pharmacological, and toxicological conditions are different in M and F, and that these differences may be related to the sex-hormone-regulated expression and action of transporters in the apical and basolateral membrane of nephron epithelial cells. In this review we have collected published data on gender differences in renal functions, transporters and other related parameters, and present our own microarray data on messenger RNA expression for various transporters in the kidney cortex of M and F rats. With these data we would like to emphasize the importance of sex hormones in regulation of a variety of renal transport functions and to initiate further studies of gender-related differences in kidney structure and functions, which would enable us to better understand occurrence and development of various renal diseases, pharmacotherapy, and drug-induced nephrotoxicity in humans and animals.

Tissue-specific distribution of the androgen receptor (AR) in the porcine fetus

The aim of this study was to investigate androgen receptor (AR) expression in developing porcine fetuses. The localization of AR was examined on embryos obtained at different days of gestation: days 18, 32, 50, 71, 90 post coitum (p.c.), and in the several tissues collected from the newborn piglets of both sexes. AR expression was first observed on day 32 p.c. in the mesonephron region. RT-PCR did not show AR mRNA on day18 p.c., but the message was present starting from day 32. In the male differentiating gonads and in the male genital ducts AR protein was present at 50, 71 and 90 days of gestation. AR protein was also detected in the cords of stromal cells within the medulla of the ovary and in stromal cells investing the oogonial nests. Pregranulosa cells on day 90 of gestation and on day 1 post partum (p.p.) immunolabelled positively for AR. In the kidney, a number of AR-positive tubules were visible while the mesenchyme in the kidney was AR-negative. Immunoreactive AR was detected predominantly in the nuclei of epithelial cells of the budding component at different stages of gestation of porcine lung. The presence of AR during gestation in non-gonadal tissues suggests a role of androgen in these tissues.

Immunohistochemical Localization of Androgen Receptor in Two Subpopulations of Porcine Granulosa Cells In Vitro

In the ovarian follicles of mammals, androgens are utilized as substrates for estrogen synthesis or can act via androgen receptor (AR). Within the ovary, granulosa cells generally display the strongest immunoreactivity for AR protein. Therefore, the aim of the present study was to analyse possible changes in the intensity of AR staining in cultured mural and antral granulosa cells isolated from follicles at various stages of development. Porcine ovaries were obtained at a local slaughterhouse and the follicles were classified as small, medium and large dependently on their diameter. Isolated granulosa cells were separated into two populations, mural and antral, and then the cells were cultured during 48 h. After this time the cells were fixed and immunostained to visualize the AR. Androgen receptor immunostaining was detected in both, antral and mural granulosa cell cultures isolated from follicles at all stages of the development. In the mural granulosa cultures the immunostaining was comparatively weaker than that in the antral granulosa cells originating from all types of follicles. Our results provide immunohistochemical evidence that antral granulosa layer is the main site of AR immunoexpression.

Effects of testosterone and nandrolone on cardiac function: a randomized, placebo-controlled study

BACKGROUND

Androgens have striking effects on skeletal muscle, but the effects on human cardiac muscle function are not well defined, neither has the role of metabolic activation (aromatization, 5alpha reduction) of testosterone on cardiac muscle been directly studied.

OBJECTIVE

To assess the effects of testosterone and nandrolone, a non-amplifiable and non-aromatizable pure androgen, on cardiac muscle function in healthy young men.

DESIGN

Double-blind, randomized, placebo-controlled, three-arm parallel group clinical trial.

SETTING

Ambulatory care research centre.

PARTICIPANTS

Healthy young men randomized into three groups of 10 men.

INTERVENTION

Weekly intramuscular injections of testosterone (200 mg mixed esters), nandrolone (200 mg nandrolone decanoate) or matching (2 ml arachis oil vehicle) placebo for 4 weeks.

MAIN OUTCOME MEASURES

Comprehensive measures of cardiac muscle function involving transthoracic cardiac echocardiography measuring myocardial tissue velocity, peak systolic strain and strain rates, and bioimpedance measurement of cardiac output and systematic vascular resistance.

RESULTS

Left ventricular (LV) function (LV ejection fraction, LV modified TEI index), right ventricular (RV) function (ejection area, tricuspid annular systolic planar motion, RV modified TEI index) as well as cardiac afterload (mean arterial pressure, systemic vascular resistance) and overall cardiac contractility (stroke volume, cardiac output) were within age- and gender-specific reference ranges and were not significantly (P < 0.05) altered by either androgen or placebo over 4 weeks of treatment. Minor changes remaining within normal range were observed solely within the testosterone group for: increased LV end-systolic diameter (30 +/- 7 vs. 33 +/- 5 mm, P = 0.04) and RV end-systolic area (12.8 +/- 1.3 vs. 14.6 +/- 3.3 cm(2), P = 0.04), reduced LV diastolic septal velocity (Em, 9.5 +/- 2.6 vs. 8.7 +/- 2.0 cm/s, P = 0.006), increased LV filling pressure (E/Em ratio, 7.1 +/- 1.6 vs. 8.3 +/- 1.8, P = 0.02) and shortened PR interval on the electrocardiogram (167 +/- 13 vs. 154 +/- 12, P = 0.03).

CONCLUSION

Four weeks of treatment with testosterone or nandrolone had no beneficial or adverse effects compared with placebo on cardiac function in healthy young men.

Gonadal steroids, salt-sensitivity and renal function

PURPOSE OF REVIEW

The aim of this article is to discuss the impact of male and female sex hormones on renal function and to develop the concept that salt-sensitivity of renal function behaves independently of the systemic blood pressure response to salt and may contribute to renal sex-specific differences.

RECENT FINDINGS

Men exhibit a more rapid age-related decline in renal function than women and some renal diseases are clearly sex dependent. Recent studies have shown that gonadal steroids have an important influence on sodium handling and renal hemodynamics that may offer a key for understanding the sexual dimorphism of the renal function. It has been found that androgens increase proximal sodium reabsorption and intraglomerular pressure by modulating afferent and efferent arteriolar tonus via angiotensin II, endothelin and oxidative stress. In contrast, female sex hormones lead to a renal vasodilation and decrease filtration fraction.

SUMMARY

Some newly discovered mechanisms triggering the salt-sensitivity of the renal function and the interaction between gonadal steroids and components of the renin cascade may play an important role in the dimorphism of renal response to salt.

Gender differences in the renin-angiotensin and nitric oxide systems: relevance in the normal and diseased kidney

Female gender is associated with better renal function and resistance to renal injury, suggesting that an oestrogen-based effect or increased androgenic effects are responsible. Studies in rodents have confirmed a biological basis for this, based on the differential effects of androgens and oestrogens on the normal and diseased kidney. Many researchers in the field believe that the pre-menopausal levels of oestrogen are key to the protection observed in females. The key pressor effects of the renin-angiotensin (RA) system are due to both direct vasoconstrictory properties and alterations in renal control of extracellular fluid volume. Additionally, the RA has been shown to promote diverse aspects of renal injury. RA activity is positively modulated by androgens and antagonized by oestrogens. Nitric oxide (NO) is a potent vasorelaxant with a key role in renal control of extracellular fluid homeostasis. NO can variously have both protective and deleterious effects on renal injury. Endogenous oestrogen has an anti-hypertensive effect as well as protective effects against cell and organ damage, many of which are mediated via increases in NO generation. We examine how the RA- and NO-generating systems may underpin key aspects of gender differences in normal renal function and renal disease.

Differential effects of spermatogenesis and fertility in mice lacking androgen receptor in individual testis cells

Using a Cre-Lox conditional knockout strategy, we generated a germ cell-specific androgen receptor (AR) knockout mouse (G-AR(-/y)) with normal spermatogenesis. Sperm count and motility in epididymis from AR(-/y) mice are similar to that of WT (G-AR(+/y)) mice. Furthermore, fertility tests show there was no difference in fertility, and almost 100% of female pups sired by G-AR(-/y) males younger than 15 weeks carried the deleted AR allele, suggesting the efficient AR knockout occurred in germ cells during meiosis. Together, these data provide in vivo evidence showing male mice without AR in germ cells can still have normal spermatogenesis and fertility, suggesting the essential roles of AR during spermatogenesis might come from indirect cell-cell communication in a paracrine fashion. We then compared the consequences of AR loss in the spermatogenesis and fertility of G-AR(-/y) mice with two other testicular cell-specific AR(-/y) mice and total AR knockout male mice. The results provide clear in vivo evidence that androgen/AR signaling in Sertoli cells plays a direct important role in spermatogenesis and in Leydig cells plays an autocrine regulatory role to modulate Leydig cell steroidogenic function. Total AR knockout male mice have the most severe defects among these mice. These contrasting data with G-AR(-/y) mice suggest AR might have different roles in the various cells within testis to contribute to normal spermatogenesis and male fertility in mice.

Expression of androgen, oestrogen alpha and beta, and progesterone receptors in the canine prostate: differences between normal, inflamed, hyperplastic and neoplastic glands

The expression of receptor for androgen (AR), oestrogen alpha and beta (ERalpha and ERbeta) and progesterone (PR) was examined immunohistochemically in canine prostate specimens (normal, hyperplastic, inflamed [prostatitis] or neoplastic). AR immunolabelling was seen in 100% of epithelial cells of normal and hyperplastic tissue, the corresponding figures for inflamed and carcinomatous tissue being 74% and 65%, respectively. ERalpha labelling was seen in 85% of epithelial cells in normal prostate glands, the corresponding figures for hyperplastic, inflamed and neoplastic glands being 35%, 22% and 12%, respectively. ERbeta labelling was seen in 85% of epithelial cells of normal glands and in about 70% of such cells in glands showing pathological changes. On the other hand, PR expression (weak) in normal glands was observed in fewer epithelial cells (44%) than in hyperplastic (70%), inflamed (62%) or neoplastic (64%) glands.

Testosterone supplementation in aging men and women: possible impact on cardiovascular-renal disease

Treatment of aging men and women with testosterone supplements is increasing. The supplements are given to postmenopausal women mainly to improve their libido and to aging men to improve muscle mass and bone strength, to improve libido and quality of life, to prevent and treat osteoporosis, and, with the phosphodiesterase-5 inhibitors, such as sildenafil, to treat erectile dysfunction. The increased use of testosterone supplements in aging individuals has occurred despite the fact that there have been no rigorous clinical trials examining the effects of chronic testosterone on the cardiovascular-renal disease risk. Studies in humans and animals have suggested that androgens can increase blood pressure and compromise renal function. Androgens have been shown to increase tubular sodium and water reabsorption and activate various vasoconstrictor systems in the kidney, such as the renin-angiotensin system and endothelin. There is also evidence that androgens may increase oxidative stress. Furthermore, the kidney contains the enzymes necessary to produce androgens de novo. This review presents an overview of the data from human and animal studies in which the role of androgens in promoting renal and cardiovascular diseases has been investigated.

Immunohistochemical study of androgen receptors in breast carcinoma. Evidence of their frequent expression in lobular carcinoma

Androgens and androgen receptors (AR) are involved in the pathogenesis of breast cancer. Epidemiological studies have shown a significant association between the risk of breast cancer and androgens. However, the functional role and clinical value of AR expression in breast carcinoma have still not been clearly defined. The present study was set up to investigate the prevalence of ARs in a series of consecutive invasive breast carcinomas (IBCs) and to evaluate the patterns of AR phenotypes in a series of selected invasive lobular carcinomas (ILCs). Among the 250 consecutive IBCs (consisting of 212 ductal and 38 lobular neoplasms), AR immunoreactivity was observed in 151/250 (60.4%) cases, being expressed in 118/212 (56%) ductal and 33/38 (87%) lobular carcinomas (a statistically significant difference, chi2=11.82). AR expression was frequently associated with ER (65.2%, chi2=14.33) and PR positivity (66.9%, chi2=7.36). Most AR positive cases showed a low proliferative index (63.7%) and a low or intermediate histological grade (G1-G2, 63.9%). Among the 80 selected ILCs, AR expression was observed in 64/80 (80%) cases. Our results confirm that ARs are expressed in most breast cancers. Moreover, we demonstrated that AR positivity is particularly marked in lobular neoplasms. In addition, AR positive carcinomas are frequently characterized by a low or intermediate grade, a low proliferative index and ER and/or PR co-expression.

Androgen receptor-mediated regulation of the alpha-subunit of the epithelial sodium channel in human kidney

Rodents studies suggest that androgens are involved in sex-specific differences in blood pressure. In humans, there is no difference in blood pressure between boys and girls, but after puberty, blood pressure increases more in men than in women. We investigated androgen-dependent regulation of the alpha-subunit of the epithelial sodium channel (alphaEnaC) in human kidney and in the human renal cell line immortalized human renal proximal tubular cell line (HKC-8). We used microarray technique to analyze androgen-dependent gene regulation and performed quantitative RT-PCR for verification. Promoter constructs for human alphaENaC were used in transfection studies to analyze the regulation by testosterone. We investigated the in vivo effect of testosterone on alphaENaC in a rat model and used the mouse collecting duct cell line M-1 for transepithelial electrophysiological measurements. The androgen receptor (AR) was expressed in male kidney and HKC-8 cells. AlphaENaC mRNA expression increased 2- to 3-fold after treatment with testosterone in HKC-8 cells. The induction by testosterone was completely blocked by adding the AR antagonist flutamide. Analysis of the alphaENaC promoter sequence identified a putative AR response element (ARE) located 140 nucleotides upstream from the transcription start site. HKC-8 cell transfection studies showed that testosterone directly upregulated gene expression via this ARE. In vivo, testosterone treatment of orchiectomized rats resulted in an increased renal alphaENaC mRNA expression. In testosterone-treated mouse M-1 cells, amiloride caused a significant stronger decrease in short circuit current than in control cells. These data show that alphaENaC expression is directly regulated by androgens in vitro and in vivo and highlight a potential mechanism explaining the reported gender differences in blood pressure.

Androgen receptor expression in ductal carcinoma in situ of the breast: not a helpful marker for classification such as estrogen receptor alpha and progesterone receptor

Androgen receptor (AR) is known to be expressed in approximately 70 to 90% of invasive breast cancers, but there are still conflicting data in terms of AR expression in ductal carcinoma in situ (DCIS). The aim of this study was to evaluate AR expression in DCIS and to compare these results with nuclear grading and with other common endocrine-related markers. On this basis the authors performed immunohistochemical staining for estrogen receptor (ER)-alpha and ER-beta, progesterone receptor (PR), pS2, her-2/neu, and AR in 59 cases of DCIS (24 low grade, 5 intermediate grade, 30 high grade). They found a strong correlation of expression of ER-alpha (P=0.003), PR (P<0.0001), and nuclear grading. For AR expression, 44.1% of all DCIS were positive, but there was no correlation between nuclear grading (P=0.535) and the expression of the other factors. The authors conclude that AR expression in DCIS is not correlated with nuclear grading and with the expression of other known endocrine-related markers such as ER-alpha and -beta, PR, pS2, and her-2/neu. The immunohistochemical assessment of AR status, therefore, may not help in providing a more objective way of classifying DCIS.

Sex steroid hormone receptors in human skin appendage and its neoplasms

Sex steroids have been postulated to influence pathophysiology of human skin through various skin appendages. The presence of sex steroid receptors has been also reported in adnexal tumors but its details still remained unknown. Therefore, in this study, we immunolocalized sex steroid receptor protein (estrogen receptor (ER)alpha, ERbeta, progesterone receptor (PR)A, PRB and androgen receptor (AR)) in 23 cases of non-pathological skin (male: 10, female: 13) and in 50 cases of skin adnexal tumors (male 24, female 26; 38 benign and 12 malignant). ERalpha immunoreactivity was detected exclusively in basal cells of sebaceous glands of non-pathological skin. AR and PRB immunoreactivity was detected in both differentiated and basal cells of sebaceous gland. AR and ERbeta immunoreactivity was also detected in sebaceous and eccrine sweat glands but not in outer root sheath of hair follicles. In sebaceous gland neoplasms, the number of ERalpha positive cases was significantly lower in skin appendage neoplasms than non-pathological skin. ERbeta immunoreactivity was not detected in any of sebaceous gland neoplasms examined. There were no significant differences in PRA, PRB and AR immunoreactivity between non-pathological sebaceous gland and its neoplasm. In sweat gland neoplasms, the number of AR positive cases was significantly lower in benign neoplasms than their non-pathological counterpart. Therefore sex steroids are considered to play important roles in regulation of non-pathological skin appendage function and pathogenesis and/or development of its neoplasm. In addition, the status of the great majority of sex steroid hormone receptors was maintained throughout the process of neoplastic transformation of skin appendages, except for AR and ERalpha in sweat and sebaceous gland neoplasms.

Effect of testosterone on the female anterior cruciate ligament

Injuries to the anterior cruciate ligament (ACL) result in immediate and long-term morbidity and expense. Young women are more likely to sustain ACL injuries than men who participate in similar athletic and military activities. Although significant attention has focused on the role that female sex hormones may play in this disparity, it is still unclear whether the female ACL also responds to androgens. The purpose of this study was to determine whether the female ACL was an androgen-responsive tissue. To identify and localize androgen receptors in the female ACL, we used Western blotting and immunofluorescent labeling, respectively, of ACL tissue harvested during surgery from young women (n = 3). We then measured ACL stiffness and assessed total testosterone (T) and free [free androgen index (FAI)] testosterone concentrations, as well as relative estradiol to testosterone ratios (E(2)/T and E(2)/FAI) at three consecutive menstrual stages (n = 20). There were significant rank-order correlations between T (0.48, P = 0.031), FAI (0.44, P = 0.053), E(2)/T (-0.71, P < 0.001), E(2)/FAI (-0.63, P = 0.003), and ACL stiffness near ovulation. With the influences of the other variables controlled, there were significant negative partial rank-order correlations between ACL stiffness and E(2)/T (-0.72, P < 0.001) and E(2)/FAI (-0.59, P = 0.012). The partial order residuals for T and FAI were not significant. These findings suggest that the female ACL is an androgen-responsive tissue but that T and FAI are not independent predictors of ACL stiffness near ovulation. Instead, the relationship between T, FAI, and ACL stiffness was likely influenced by another hormone or sex hormone binding globulin.

Androgen receptor expression is inversely correlated with pathologic tumor stage in bladder cancer

OBJECTIVES

To evaluate the expression of the androgen receptor (AR) in transitional cell carcinoma (TCC) of the bladder, and to assess whether its expression correlated with pathologic tumor stage. TCC of the bladder is three times more common in males than in females. The origin of this sex difference in incidence is unknown.

METHODS

We evaluated tumor specimens from 49 consecutive patients treated for TCC of the bladder at our institution between July 2002 and June 2003. Immunohistochemistry was performed using a monoclonal mouse anti-AR antibody on paraffin-embedded tissue sections of tumors obtained from transurethral resection, radical cystectomy, or resection of metastases. Specimens were assessed for AR expression, and, in tumors that demonstrated AR staining, the percentage of nuclei that stained positive was recorded.

RESULTS

Of the 49 tumors, 26 (53.1%) expressed the AR. The percentage of tumors that expressed the AR decreased with increasing pathologic stage, from 88.9% of pTa lesions to 0% of pT3 tumors. Overall, 75% of superficial tumors (pTa + pT1 + carcinoma in situ) expressed the AR compared with 21.4% of invasive tumors (pT2 + pT3; P = 0.002). In addition, among AR-expressing tumors, the mean percentage of nuclei that stained positive for the AR was significantly greater in pTa tumors (62.5%) than in pT1 (31%) or pT2 (20%) tumors (P = 0.005).

CONCLUSIONS

We found a decrease in AR protein expression in tumors with increased pathologic stage. Our data suggest that the loss of AR expression is associated with invasive bladder cancer.

Keratins of the Human Hair Follicle

Substantial progress has been made regarding the elucidation of differentiation processes of the human hair follicle. This review first describes the genomic organization of the human hair keratin gene family and the complex expression characteristics of hair keratins in the hair-forming compartment. Sections describe the role and fate of hair keratins in the diseased hair follicle, particularly hereditary disorders and hair follicle-derived tumors. Also included is a report on the actual state of knowledge concerning the regulation of hair keratin expression. In the second part of this review, essentially the same principles are applied to outline more recent and, thus, occasionally fewer data on specialized epithelial keratins expressed in various tissue constituents of the external sheaths and the companion layer of the follicle. A closing outlook highlights issues that need to be explored further to deepen our insight into the biology and genetics of the hair follicle.

Localization of steroid hormone receptors in the apocrine sweat glands of the human axilla

The apocrine axillary glands, regarded as pheromone-producing scent glands, do not begin to function until puberty. Accordingly, sex hormones should have an impact on their activity, and the present study was designed to investigate the localization of androgen receptor (AR) and estrogen receptors (ERalpha and ERbeta) in those glands. Strong nuclear immunoreactivity for AR and ERbeta was found in the secretory epithelium. In AR especially, staining intensity was correlated with the height of the epithelium with more intense immunoreactivity in tall segments. Since the lower epithelium has been considered inactive or resting, our results suggest a correlation between steroid-receptor expression and secretory activity. Androgens are known to upregulate the cholesterol biosynthesis, and cholesterol may be used as precursor for pheromones. Accordingly, the results of this study establish a possible link between steroid hormone action and induction of pheromone production in the apocrine axillary glands.

Hormonal regulation of spermatogenesis

Proper functioning of the mammalian testis is dependent upon an array of hormonal messengers acting through endocrine, paracrine, and autocrine pathways. Within the testis, the primary messengers are the gonadotrophins, follicle stimulating hormone and luteinizing hormone, and the androgens. Abundant evidence indicates that the role of the gonadotrophins is to maintain proper functioning of testicular somatic cells. It is the androgens, primarily testosterone, which act through the somatic cells to regulate germ cell differentiation. Despite extensive research in this area, little is known about the cell-specific requirements for androgens and even less is understood about the downstream effectors of androgen signalling. However, recent work using cell-specific ablation of androgen receptor function has demonstrated a clear requirement for androgen signalling at multiple, discrete time points during spermatogenesis. These models also provide useful tools for identifying the targets of androgen receptor activity. The purpose of this review is to provide a brief overview of recent advances in our understanding of hormonal regulation of spermatogenesis, with an emphasis on the role of testosterone within the testis, and to pose important questions for future research in this field.

Involvement of glucocorticoids in testicular involution after active immunization of boars against GnRH

Active GnRH immunization of boars inhibits LH and testicular steroids but the consequences for spermatogenesis are unknown. Six boars were immunized three times against GnRH at 20, 24 and 28 weeks. Another six boars served as controls. Plasma LH and FSH were determined at 28 and 31 weeks. Testosterone and cortisol were determined before killing the pigs at 32 weeks. Tissue samples were taken for histology and fluid from the seminiferous tubuli for steroid determination. Individual germ cells were counted in histological sections. The glucocorticoid receptor (GCR), mitosis of spermatogonia and apoptosis were characterized by immunocytochemistry. Immunization reduced LH and testosterone to base levels whereas FSH was not changed. Testis weight was reduced by 64% due to a loss of Leydig cell cytoplasm (90.3%) and a decrease of tubule diameters (60.6%). Except for A-spermatogonia, all other spermatogenic cells were reduced by about 60%. Mitosis was reduced in immunized boars. Expression of GCRs was limited to spermatogonia and differed between immunized boars (8% of spermatogonia) and controls (2%). In the controls, androgen concentrations in tubular fluid were tenfold higher compared with immunized boars. Cortisol concentrations were of the order of 40 nmol/l both in the tubular fluid and blood plasma. These concentrations did not differ between groups. Apoptosis occurred only in spermatogonia and pachytene spermatocytes and was twofold higher in immunized boars compared with controls. Thus the availability of glucocorticoids in the tubuli and the expression of GCRs initiate apoptosis, which in turn reduces sperm yield. Testosterone is known to be an inhibitor of GCR expression, thus increasing the efficiency of spermatogenesis.

Androgen regulation of the human hair follicle: the type I hair keratin hHa7 is a direct target gene in trichocytes

Previous work had shown that most members of the complex human hair keratin family were expressed in terminal scalp hairs. An exception to this rule was the type I hair keratin hHa7, which was only detected in some but not all vellus hairs of the human scalp (Langbein et al, 1999). Here we show that hHa7 exhibits constitutive expression in medullary cells of all types of male and female sexual hairs. Medullated beard, axillary, and pubic hairs arise during puberty from small, unmedullated vellus hairs under the influence of circulating androgens. This suggested an androgen-controlled expression of the hHa7 gene. Further evidence for this assumption was provided by the demonstration of androgen receptor (AR) expression in the nuclei of medullary cells of beard hairs. Moreover, homology search for the semipalindromic androgen receptor-binding element (ARE) consensus sequence GG(A)/(T)ACAnnnTGTTCT in the proximal hHa7 promoter revealed three putative ARE motifs. Electrophoretic mobility shift assays demonstrated the specific binding of AR to all three hHa7 AREs. Their function as AR-responsive elements, either individually or in concert within the hHa7 promoter, could be further confirmed by transfection studies with or without an AR expression vector in PtK2 and prostate PC3-Arwt cells, respectively in the presence or absence of a synthetic androgen. Our study detected hHa7 as the first gene in hair follicle trichocytes whose expression appears to be directly regulated by androgens. As such, hHa7 represents a marker for androgen action on hair follicles and might be a suitable tool for investigations of androgen-dependent hair disorders.

Androgens augment proximal tubule transport

The proximal tubule contains an autonomous renin-angiotensin system that regulates transport independently of circulating angiotensin II. Androgens are known to increase expression of angiotensinogen, but the effect of androgens on proximal tubule transport is unknown. In this in vivo microperfusion study, we examined the effect of androgens on proximal tubule transport. The volume reabsorptive rate in Sprague-Dawley rats given dihydrotestosterone (DHT) injections was significantly higher than in control rats given vehicle injections (4.57 +/- 0.31 vs. 3.31 +/- 0.23 nl x min(-1) x mm(-1), P < 0.01). Luminally perfusing with either enalaprilat (10(-4) M) to inhibit production of angiotensin II or losartan (10(-8) M) to block the angiotensin receptor decreased the proximal tubule volume reabsorptive rate in DHT-treated rats to a significantly greater degree than in control vehicle-injected rats. The renal expression of angiotensinogen was shown to be higher in the DHT-treated animals, using Northern blot analysis. The expression of angiotensin receptors, determined by specific binding of angiotensin II, was not different in the two groups of animals. Brush-border membrane protein abundance of the Na/H exchanger, a membrane transport protein under angiotensin II regulation, was also higher in DHT-treated rats vs. control rats. Rats that received DHT had higher blood pressures than the control rats but had no change in their glomerular filtration rate. In addition, serum angiotensin II levels were lower in DHT-treated vs. control rats. These results suggest that androgens may directly upregulate the proximal tubule renin-angiotensin system, increase the volume reabsorptive rate, and thereby increase extracellular volume and blood pressure and secondarily decrease serum angiotensin II levels.

Androgen regulates follicle-stimulating hormone beta gene expression in an activin-dependent manner in immortalized gonadotropes

Little is known about the molecular mechanisms of androgen regulation of the FSHbeta gene; however, studies suggest that it consists of a complex feedback loop that involves multiple mechanisms acting at both the level of the hypothalamus and the pituitary. In the present study, we address androgen regulation of the FSHbeta gene in immortalized gonadotrope cells and investigate the roles of activin and GnRH in androgen action. Using transient transfection assays in the FSHbeta-expressing mouse gonadotrope cell line, LbetaT2, we demonstrate that androgens stimulate expression of an ovine FSHbeta reporter gene in a dose-dependent manner. Mutation of either of two conserved androgen response elements at -245/-231 and -153/-139 within the proximal region of the ovine FSHbeta gene promoter abolishes this stimulation, and androgen receptor binds directly to the -244 ARE in vitro. Androgen induction of the FSHbeta reporter gene is also dependent upon the activin autocrine loop present in the LbetaT2 cells, as well as an activin-response element at -138/-124 of the FSHbeta gene. However, activin regulation of other genes remains unaffected by androgens. In addition, androgens stimulate expression of a mouse GnRH receptor reporter gene, and thus may indirectly augment the response of the FSHbeta gene to GnRH. Taken together, these data demonstrate that, in mouse gonadotropes, androgens act directly on the ovine FSHbeta gene to stimulate expression by a mechanism that is dependent upon activin, as well as acting indirectly, potentially through a second mechanism that may be dependent upon induction of GnRH receptor.

Expression study of three secretory proteins (prostatic secretory protein of 94 amino acids, probasin, and seminal vesicle secretion II) in dysplastic and neoplastic rat prostates

BACKGROUND

Prostatic secretory protein of 94 amino acids (PSP94), probasin, and seminal vesicle secretion II (SVSII) are the three major proteins secreted by the lateral lobe of the rat prostate gland. Among these proteins, rodent PSP94 but not probasin and SVSII has a human homologue and it is also a major secretory protein of the human prostate, in addition to prostatic acid phosphatase and prostate-specific antigen.

METHODS

In this study, we examined and compared the mRNA expression of these three secretory markers in three rat models of prostate cancer including the sex steroid-induced dysplasia (prostatic intraepithelial neoplasia or PIN) in Noble (Nb) rat model, an androgen-independent Nb rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas (both androgen-dependent and -independent) by in situ hybridization (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR), and immunohistochemistry.

RESULTS

The transcripts for the three markers were highly expressed in the secretory epithelium of normal lateral prostate (LP). Their hybridization signals became reduced in the epithelial cells in the low-grade PINs and significantly weakened or lost in the high-grade PINs induced in the LP. Interestingly, we observed that some dysplastic cells located at the basal compartment of the PIN lesions, and nests of outpouching epithelial cells in the vicinity of PINs, expressed positive hybridization signals of three markers. In the adenocarcinoma, signals of probasin but not PSP94 and SVSII were detected. No hybridization signals were detected in both Dunning and AIT tumors. By RT-PCR, transcripts for these proteins were still detected but significantly reduced in the Dunning tumors, whereas in the AIT tumor, only SVSII transcripts were detected. Immunohistochemistry of PSP94 also showed a reduced staining in the PIN lesions, but no immunoreactivity was seen in the rat prostatic tumors.

CONCLUSIONS

The mRNA expression of the three prostatic secretory markers were decreased in the hormone-induced PINs and in two rat prostatic tumors, indicating that the androgen-regulated secretory differentiation was impaired during the development of the premalignant lesion and further reduced in advanced tumors. The abnormal expression pattern of these secretory markers and androgen receptor (AR) in the basal compartment of the PIN lesions suggests that there is a population of cell types with secretory phenotype appearing in the basal cell layer during the early malignant transformation of the prostatic epithelium.

Immunohistochemical localization of steroidogenic enzymes in human follicle following xenotransplantation of the human ovarian cortex into NOD-SCID mice

There have been reports of successful follicular growth following xenogenic transplantation of the human ovarian cortex into immunodeficient mice. In this study, we examined the immunohistochemical expression and localization of steroidogenic enzymes in the graft of nonpathological human ovary following xenogenic transplantation into nonobese diabetic severe combined immune deficient (NOD-SCID) mice. We studied human follicles following xenotransplantation into NOD-SCID mice using immunohistochemistry antibodies against the cell proliferation marker (Ki 67), steroidogenic enzymes P450 cholesterol side chain cleavage (P450 scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), cytochrome P450 17alpha hydroxylase (P450 c17), cytochrome P450 aromatase (P450 arom), androgen receptor (AR), estrogen receptor (ER), and Ad4-binding protein (Ad4BP), a transcription factor for all steroidogenic P450 genes. In the pre-antral follicles of these grafts, Ki 67 and Ad4BP were detected in both the theca and granulosa cell layer. P450 scc, P450 c17, 3beta-HSD, and AR were present in only the theca cell layer, observations of which were consistent with the findings of nonpathological human ovarian cortex. P450 arom and ER were not detected in these grafts, however, and these follicles did not possess any specific feature of a dominant follicle. These findings suggest that the expression of steroidogenic enzymes in human follicles following xenogenic transplantation into NOD-SCID mice is similar to that of nonpathological human ovaries. However, these follicles do not possess any features of dominant follicles, which are known to develop into the corpus luteum.

Correlation of androgen receptors, aromatase, and 5-alpha reductase in the human vagina with menopausal status

OBJECTIVE

To determine whether aromatase and 5alpha-reductase mRNAs are expressed in human vagina and to evaluate the presence of androgen receptors in human vaginal tissue based on age and menopausal status.

DESIGN

Prospective study.

SETTING

Specimens obtained from clinical renal urology practice.

PATIENT(S)

Premenopausal and postmenopausal women undergoing surgery for prolapse or incontinence.

MAIN OUTCOME MEASURE(S)

Expression of aromatase and 5alpha-reductase type 1 and 2 mRNAs was evidenced by reverse transcriptase-polymerase chain reaction (RT-PCR), and the density of androgen receptors was measured by semiquantitative immunohistochemistry.

RESULT(S)

The mRNAs for aromatase and 5alpha-reductase isotypes 1 and 2 were detected in vaginal specimens. Androgen receptors were present in vaginal mucosa, submucosa, stroma, smooth muscle, and vascular endothelium. Expression was significantly greater in vaginal submucosa. A negative correlation existed between age and androgen receptor density.

CONCLUSION(S)

Expression of genes encoding for enzymes involved in testosterone metabolism in the human vagina, as well as androgen receptor location, density, and changes with menopausal status, suggests that androgens may play a role in regulating vaginal smooth muscle and vaginal blood flow.

Androgens and the development of the vagina

Today it is generally held that the vagina develops from sinovaginal bulbs and that the lower third of the definitive vagina is derived from the urogenital sinus. Here we show that the entire vagina arises by downward growth of Wolffian and Müllerian ducts, that the sinovaginal bulbs are in fact the caudal ends of the Wolffian ducts, and that vaginal development is under negative control of androgens. We designed a genetic experiment in which the androgen receptor defect in the Tfm mouse was used to examine the effects of androgens. Vaginal development was studied by 3D reconstruction in androgen-treated female embryos and in complete androgen-insensitive littermates. In androgen-treated females, descent of the genital ducts was inhibited, and a vagina formed in androgen-insensitive Tfm embryos as it does in normal females. By immmunohistochemical localization of the androgen receptor in normal mouse embryos, we demonstrated that the androgen receptor was expressed in Wolffian duct and urogenital sinus-derived structures, and was entirely absent in the Müllerian duct derivatives. We conclude that the Wolffian ducts are instrumental in conveying the negative control by androgens on vaginal development. The results are discussed under evolutionary aspects at the transition from marsupial to eutherian mammals.

Androgen receptors in gonadotrophs in pituitary cultures from adult male monkeys and rats

There is substantial evidence demonstrating that the principal feedback action of androgens to decrease LH secretion in male primates, including man, is to slow the GnRH pulse generator, whereas in male rats androgens not only decrease GnRH but also suppress LH synthesis and secretion through a direct pituitary effect. Previous experiments in our laboratory revealed that testosterone (T) suppresses LH secretion and decreases alpha-subunit mRNA levels in male rat pituitary cell cultures perifused with pulses of GnRH but not in pituitary cells from adult male monkeys. In the present study, we sought to determine whether the lack of responsiveness of gonadotrophs to androgens in the primate is androgen receptor (AR) related. Primary cultures were prepared from the anterior pituitary glands of adult male monkeys and rats. Cells were identified as gonadotrophs if they were immunoreactive for LH-beta or FSH-beta. Of these cells in the monkey, 80% contained both gonadotropins, 17% contained only LH-beta, and 3% contained only FSH-beta. AR immunoreactivity (IR) was nuclear in 22% and 15%, respectively, of monkey and rat FSH-beta-positive cells in the absence of T. Following T treatment, nuclear AR IR was identified in 79% of monkey and 81% of rat gonadotrophs. T treatment similarly intensified AR IR in mouse gonadotroph alphaT3-1 and LbetaT2 cells and in monkey and rat fibroblasts. Single-cell RT-PCR confirmed coexpression of LH-beta and AR mRNA as well as LH-beta and GH mRNA in monkey gonadotrophs. Our data reveal that most monkey, as well as rat, gonadotrophs are AR-positive with nuclear localization in the presence of T. GH expression is not required for AR expression in gonadotrophs. We conclude that the failure of T to inhibit LH secretion and decrease alpha-subunit mRNA expression in the male primate is not due a disturbance in AR nuclear shuttling.

Levels of urinary inter-alpha-trypsin inhibitor trimer as a function of age and sex-hormone status in males and females not forming stones

OBJECTIVES

To determine if levels of inter-alpha-trypsin inhibitor (I alpha TI)-trimer differ in normal individuals based on age, gender or hormonal status, as the regulation of calcium oxalate (CaOx) crystallization inhibitors, e.g. by sex steroids, could be a mechanism contributing to the differences in CaOx urolithiasis between the sexes.

SUBJECTS AND METHODS

Voided urine samples were collected from normal males and females. In Experiment 1 samples were grouped by gender and age, i.e. paediatric (PED) < or = 10 years, male (M) 21, female (F) 14; young adult (YGAD) 20-30 years, M 23, F 18; adults (AD), 35-50 year, M 25, F 13; adults aged > or = 60 years (> 60), M 24, F 16 (totals, M 93, F 61). In Experiment 2 samples were grouped by gender, age and hormonal status, i.e. PED, M 24, F 17; AD, M 24, F 22; > 60 and not on hormonal therapy, M 23, F 30; M > 60 and on androgen deprivation therapy (ANDEP) 18; and F > 60 on oestrogen supplementation, F+EST, 18 (total M 89, F 85). Levels of urinary I alpha TI-trimer were determined by immunoblotting and enhanced chemiluminescence, and relative densities of the bands determined.

RESULTS

In both experiments the relative levels of I alpha TI-trimer were 2-7 times higher in M-PED than in all other groups of males (P < or = 0.007). Among adult males, I alpha TI-trimer levels were similar in all groups, including ANDEP (P > or = 0.9). There were no differences in the relative levels of I alpha TI-trimer among any of the groups of females, regardless of age or hormonal status (P > or = 0.7).

CONCLUSIONS

In males a decrease in I alpha TI-trimer was associated with the onset of adulthood and entry into the 'stone-forming years'. Females did not show this decrease, and neither sex showed an increase in I alpha TI-trimer in the > 60 group, when the incidence of CaOx urolithiasis is supposedly declining. While changes in urinary I alpha TI-trimer levels in males may reflect maturational changes in the kidney, overall these data do not support the hypothesis that the age-related changes in the incidence of urolithiasis are paralleled by changes in the expression I alpha TI-trimer. Additionally, the sex steroids do not appear to acutely regulate the expression of I alpha TI-trimer in adults, making differences in I alpha TI-trimer levels unlikely to be the reason for the disparity in the incidence of CaOx urolithiasis between the sexes.

Apoptosis-related proteins and steroid hormone receptors in normal, hyperplastic, and neoplastic endometrium

The purpose of this study was to evaluate the distribution and frequency of apoptosis-related proteins and their correlation with estrogen, progesterone, and androgen receptors in endometrial tissues. Immunohistochemical analyses of bcl-2, bax, bcl-x, and steroid receptors were performed in 22 endometrial carcinomas, 26 endometrial hyperplasias, and 19 cases of normal cyclical endometrium. Bcl-2 was expressed in 45.4% of carcinomas and 92.3% of hyperplasias. Bax immunostaining was found in 90.9% of carcinomas and 76.9% of hyperplasias. Bcl-x positivity was similar in carcinomas (68.1%) and endometrial hyperplasias (76.9%). In normal cyclical endometria, bcl-2 staining was intense and diffuse in the proliferative phase, but decreased dramatically in the early and mid-secretory phase to reappear in the late secretory phase. Bax was expressed throughout the menstrual cycle but more strongly in the secretory phase. Bcl-x displayed a similar degree of expression in proliferative and secretory endometria. Nineteen carcinomas (86.3%), 25 hyperplasias (96.1%), and 18 normal cyclical endometria (94.7%) were positive for estrogen receptor (ER). Progesterone receptor (PR) was observed in 20 carcinomas (90.9%), all hyperplasias (100%), and 18 normal cyclical endometria (94.7%). Androgen receptor (AR) positivity was seen in 7 carcinomas (31.8%), 6 hyperplasias (23.0%), and 3 normal cyclical endometria (15.7%). There was a statistically positive correlation between bcl-x and ER and a tendency toward significant correlation between bcl-x and PR and between ER and PR in carcinomas. In hyperplasias, there was a significant positive correlation between bcl-2 and PR and between bcl-2 and bax and a negative correlation between ER and bax. There was a statistically significant difference for bcl-2 (p = 0.001) and bax (p = 0.001) between the hyperplasia and carcinoma groups. There was increased expression of bax, decreased expression of bcl-2, and persistence of bcl-x protein in advanced endometrial carcinomas. Our findings show that ovarian hormones have a regulatory role on bcl-2 protein and that there is a correlation between other members of the bcl-2 family (bcl-x and bax) and steroid hormone receptors. Bax/bcl-x may be the major control mechanisms of apoptosis in advanced carcinomas; other members of the bcl-2 family may also be under hormonal control.

Characterization of androgen receptor and nuclear receptor co-regulator expression in human breast cancer cell lines exhibiting differential regulation of kallikreins 2 and 3

Accumulating evidence indicates that androgens and the androgen receptor modulate the development and progression of breast adenocarcinoma; however, the precise role and actions remain poorly defined. We examined previously the steroid hormone regulation of 2 known androgen-regulated kallikreins, KLK3 (encoding PSA) and KLK2 (encoding human kallikrein 2 or hK2) in BT-474, T-47D, ZR75-1, MCF-7, MFM-223 and BT-20 human breast cancer cells and found that they were differentially regulated, with the cells showing variable responses to androgen. To determine if this variable response was reflected by differences in androgen receptor, we characterized the expression of androgen receptor in these cells by Western blot analysis and saturation binding analysis. In addition, we sequenced androgen receptor cDNA from each of these cell lines to check whether any androgen receptor mutations were present. The expression of 11 nuclear receptor co-regulatory factors (SRC-1, AIB1, ARA24, ARA54, ARA55, ARA70, ARA160, FHL2, PDEF, NCoR1, SMRT) was compared in these cell lines by semi-quantitative RT-PCR to determine if the pattern of receptor co-activators or -repressors expressed in these cells might explain the differential regulation of KLK2 and KLK3. The levels of androgen receptor varied among the cell lines, but did not correlate with hK2 and PSA secretion determined previously. No mutations within the coding regions of the receptor were detected. With the exception of receptor expressed by MCF-7 cells, the polymorphic CAG repeat length was in the normal range. Every breast cancer cell line exhibited a distinct expression pattern of the nuclear receptor co-regulators examined raising the possibility that the relative levels of these co-activators/-repressors might differentially modulate androgen receptor transcriptional activity within the promoter/enhancer region of KLK2 and KLK3 of these cells.

Immunohistochemical detection of androgen receptors in the canine uterus throughout the estrus cycle

Serum androgen levels in the bitch increase during proestrus and remain elevated until metestrus. To find out whether androgens can have a direct impact on the canine uterus, androgen receptors (AR) were identified immunohistochemically in uterine tissue. Androgen receptor distribution in the uterine horns, body and cervix was described during different cycle stages, during pregnancy and in the postpartum period. Nuclear staining for AR was observed in cells of the surface epithelium, glandular ducts, basal glands and stroma of the endometrium, and in myometrial smooth muscle cells. In addition, cytoplasmic staining was observed in epithelial cells from proestrus to early metestrus, when the cells were secretory active, and in stroma cells during pregnancy, suggesting a role for androgens in decidualization. During pregnancy and in the postpartum period nuclear staining for AR was nearly absent. During the estrus cycle stroma cells stained with higher intensities for AR than epithelial cells, supporting the idea that stroma cells mediate some effects of steroid hormones on epithelial cells in the genital tract. In contrast with earlier findings on estrogen receptor-alpha and progesterone receptors, no significant changes in androgen receptor expression were observed during the estrus cycle. Few correlations were found between the staining for AR and serum levels of the sex steroids. The present findings suggest that there is a basal expression of AR in the canine uterus throughout the estrus cycle that may not be influenced by sex steroid hormones.

Androgen receptor (AR) coregulators: an overview

The biological action of androgens is mediated through the androgen receptor (AR). Androgen-bound AR functions as a transcription factor to regulate genes involved in an array of physiological processes, most notably male sexual differentiation and maturation, and the maintenance of spermatogenesis. The transcriptional activity of AR is affected by coregulators that influence a number of functional properties of AR, including ligand selectivity and DNA binding capacity. As the promoter of target genes, coregulators participate in DNA modification, either directly through modification of histones or indirectly by the recruitment of chromatin-modifying complexes, as well as functioning in the recruitment of the basal transcriptional machinery. Aberrant coregulator activity due to mutation or altered expression levels may be a contributing factor in the progression of diseases related to AR activity, such as prostate cancer. AR demonstrates distinct differences in its interaction with coregulators from other steroid receptors due to differences in the functional interaction between AR domains, possibly resulting in alterations in the dynamic interactions between coregulator complexes.

Post-natal development of the rat testis: steroid hormone receptor distribution and extracellular matrix deposition

The control of testicular development and differentiation depends on hormones and a variety of cell-cell interactions mediated mainly by paracrine factors. In the second and third weeks of post-natal development important changes take place in the rat testis, e.g. the tubular lumen starts to open on post-natal day 10, the blood-testis barrier starts to form on day 15, and Sertoli cell proliferation ceases on day 15. In the present study the expression in different testicular compartments of the androgen receptor (AR), progesterone receptor (PR), and extracellular matrix proteins such as laminin, entactin-1 (nidogen-1) and fibronectin, during post-natal development was examined using immunohistochemistry and semiquantitative image analysis. An intratubular AR peak on days 14-17, an increase in intratubular PR expression on days 14-16, and an increase in peritubular entactin-1 expression during the second and third weeks post-partum are demonstrated. These results suggest that a variety of changes occur at the cellular level during this period when certain milestones of testicular development occur, substantiating the hypothesis of a particular role for paracrine interactions during the development of the rat testis.

Androgen receptor (AR), estrogen receptor-alpha (ER-alpha) and estrogen receptor-beta (ER-beta) expression in the testis of the newt, Triturus marmoratus marmoratus during the annual cycle

Expression of androgen receptor (AR), estrogen receptor alpha (ER-alpha) and estrogen receptor beta (ER-beta) in the testis of the marbled newt (Triturus marmoratus marmoratus) was investigated, with special attention to changes during the annual testicular cycle, using light microscopy immunohistochemistry and Western blot analysis. Primordial germ cells, primary and secondary spermatogonia and spermatocytes showed a positive reaction to the 3 receptor antibodies during the annual reproductive cycle. Follicular cells were positive to AR, ER-alpha and ER-beta during the spermiogenesis and quiescence periods in the glandular tissue. Interstitial cells showed reactivity to AR, ER-alpha and ER-beta in the spermiogenesis and the quiescence periods, and presented no labelling to these receptors in the proliferative period. These findings suggest that, as in mammals, there is an androgen-estrogen regulation of the function and development of the newt testis.

Preventing estrogen receptor action with dimer-interface peptides

The human estrogen receptor-alpha (hER) is a ligand-activated transcription factor that functions as a homodimer. We sought to further understand the molecular processes involved in dimerization, and to develop a reagent that may function as an antiestrogen independent of the ligand binding site. To this end, we designed a 16-residue 'dimer-interface' oligopeptide derived from the helical region of the hER which is directly involved in dimerization. This peptide, termed the I-box peptide, has a high helical propensity in aqueous solution. The I-box peptide blocks hER action by causing aggregation and precipitation of both the ligand-bound and apo-hER. This effect is dependent on the helical nature of the peptide. A single Ile to Pro mutation in the helical region of the I-box peptide significantly reduces the helical content and abolishes the precipitation activity. Furthermore, the peptide activity appears to be specific for the hER. The I-box peptide does not significantly affect other proteins or steroid receptors tested. A homologous peptide derived from the nuclear receptor RXRalpha dimer interface, and a LXXLL-containing peptide from the coactivator TIF2 have no detectable in vitro effect on hER function or solubility. Our data suggest that rationally designed molecules capable of affecting steroid receptor quaternary structures may be potential avenues for the development of specific inhibitors of this class of proteins.

Photoperiod-dependent capability of androgen aromatization and the role of estrogens in the bank vole testis visualized by means of immunohistochemistry

Detection of steroid hormone receptors within a target tissue is important for an understanding of their crucial role in regulating of steroids' action. In the light of recent knowledge on the role of estrogens in male gonads the efforts were undertaken to clarify and discuss a role of androgen receptors, aromatase and estrogen receptors (ER) in mediating testosterone and/or estradiol action in testicular cells of bank voles that were kept under short or long light cycles. Immunohistochemistry was performed on paraplast embedded sections of the bank vole testes. First, androgen receptors were immunolocalized in testicular somatic cells while germ cell did not express any immunoreaction. Moreover, the ability to convert androgens to estrogens by various testicular cells was documented; aromatase immunoexpression was found in testis sections, not only in Leydig cells and Sertoli cells but also in germ cells. Finally, the expression of estrogen receptor-alpha (ERalpha) was observed in Leydig cells whereas the presence of estrogen receptor-beta (ERbeta) was detected in Sertoli and germ cells, namely spermatocytes and spermatids. The cellular distribution of androgen receptors appeared to be light -and age-dependent in adults; immunoexpression of aromatase and ERbeta was found to be both age -and photoperiod-dependent in germ cells.

Androgen receptor in pituitary adenomas of the gonadotroph cell complex

Although androgen receptors have been identified in normal gonadotroph and somatotroph cells of the pituitary, immunohistochemical studies have failed to reveal these receptors in pituitary adenomas so far. Using a monoclonal antibody to androgen receptor in our series of 60 adenomas of the gonadotroph cell complex (20 FSH/LH cell adenomas, 20 null cell adenomas, 20 oncocytic adenomas), only one null cell adenoma showed strong nuclear immunostaining. All the other antibodies were completely negative. The significance of this finding in correlation with clinical data is still unclear, although it may be associated with more rapid tumor growth. In paraadenomous tissue, some normal gonadotrophs expressed the androgen receptor.

Localization of androgen receptor and cytochrome P450 aromatase in the follicle and corpus luteum of the porcine ovary

The following study was undertaken to localize androgen receptors (AR) and aromatase cytochrome P450 (P450arom) in porcine ovarian tissue because ovarian androgens may act locally to modulate follicular and luteal function in various species. Androgen receptor was detected immunohistochemically in granulosa and theca cells of preantral as well as in growing antral follicles. The most intensive staining was observed in the antral granulosa layer. Luteinizing granulosa cells of preovulatory follicles, and luteal cells from the early and midluteal phases stained weakly for the androgen receptor. Fully regressed corpora lutea in the early follicular phase of the next cycle did not stain for androgen receptor. In contrast, granulosa cells were very weakly stained for aromatase in early stages of follicular development. The P450arom was maximally expressed with the same intensity in mural and antral layers in large ovulatory follicles. Corpora lutea from the early luteal phase showed positive staining, whereas those from midluteal phase did not stain for aromatase, some cells of regressed corpora lutea unexpectedly exhibited aromatase staining.

Controls of hair follicle cycling

Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.

Expression of proteins that inhibit calcium oxalate crystallization in vitro in the urine of normal and stone-forming individuals

The factors precipitating clinically active calcium oxalate (CaOx) urolithiasis are not known. This study examined the relationships between urinary proteins that inhibit CaOx crystallization in vitro and the incidence of CaOx urolithiasis. The first hypothesis is that levels of urinary CaOx crystallization inhibitors differ between clinically active stone formers (SFs) and normal individuals. The second hypothesis is that lower levels of urinary CaOx crystallization inhibitors contribute to the two- to threefold greater incidence of CaOx urolithiasis in males compared with females. These hypotheses were derived from previous observations on the expression of urinary inter-alpha-trypsin inhibitor trimer (IalphaTI-trimer) in normal and stone-forming individuals. The proteins of void urine samples from normal volunteers (24 males, 19 females) and CaOx-SFs (26 males, 16 females) were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunoreactive IalphaTI-trimer, osteopontin, and prothrombin were detected by immunoblot plus enhanced chemiluminescence; the relative densities of the bands were then determined. With the exception of IalphaTI-trimer (P: </= 0.026, approximately twofold), there was no difference in the relative densities of CaOx crystallization inhibitors in the urine of normal and CaOx stone-forming individuals. Thus, there does not appear to be a generalized increase or decrease in levels of CaOx crystallization inhibitory proteins between normal and CaOx stone-forming individuals. The relative density of IalphaTI-trimer was approximately threefold greater in females than in males (P: </= 0.001). Differences in the relative densities of the other CaOx crystallization inhibitors were small and of questionable physiological importance. These data do not support the hypothesis that males have a greater incidence of CaOx urolithiasis because of a generalized decrease in urinary CaOx crystallization inhibitory protein levels.

Androgen receptor expression in sertoli cells as a function of seminiferous tubule maturation in the human cryptorchid testis

Androgen receptor (AR) immunohistochemistry was performed in an archival collection of adult human cryptorchid testes to determine whether AR cellular distribution and intensity of immunostaining were functions of the severity of cellular dysgenesis. The seminiferous tubule histology of cryptorchid testes collected from adults is marked by three specific patterns. 1) Seminiferous tubules are characterized as maintaining focal areas of germinal cell differentiation (albeit incomplete) that are interspersed with 2) tubules composed of Sertoli cells only, these latter cells being principally of the adult type, although dysgenetic and immature Sertoli cells may also be detected. 3) In contrast, there is a class of tubule that is characterized as being composed exclusively of Sertoli cells that are extremely dysgenetic in appearance. The majority of adult-type Sertoli cells found in the first types of tubules exhibited either robust or moderate AR staining intensity. Peritubular cells of these tubules also expressed a similar AR staining intensity. In contrast, in the more dysgenetic and immature type Sertoli cells found in the second type of tubules, the intensity of AR staining was significantly less, if not missing altogether. Finally, in the most dysgenetic tubules, Sertoli cell AR staining was never detected. To our knowledge, this is the first report in the literature that addresses the intensity of AR immunostaining in Sertoli cells of cryptorchid testes. The results presented herein are consistent with the interpretation that the intensity of AR staining in Sertoli cells diminishes as a function of the severity to which the cells are afflicted within a cryptorchid testis and that focal absence of AR expression in Sertoli cells correlates with a lack of local spermatogenesis in the tubules.

Microwave pretreatment of sections to improve the immunocytochemical detection of progesterone receptors in the guinea pig hypothalamus

The goal of this study was to evaluate the effects of microwave heat on immunocytochemical staining for progesterone receptors (PR) in frozen sections and in paraffin-embedded sections of guinea pig brain using an antibody previously shown to successfully stain only frozen sections of formalin-fixed materials. A simple, reliable and sensitive retrieval method has been adapted based on microwave irradiation of sections in citrate solution prior to incubation with the anti-PR antibody. Different pH values (3.0, 6.0 and 8.5) of the citrate buffer were tested and the pH at 6.0 was found to give the best results. PR-like immunoreactivity was markedly increased in frozen sections exposed to microwave heating compared with untreated tissue. The integrity of the tissue was not affected by this treatment and specific nuclear immunoreactivity for PR was detected in hypothalamic neurons. Staining of paraffin-embedded sections without microwave pretreatment yielded negative results while irradiation of sections enabled the labeling of hypothalamic regions known to contain progesterone binding sites. Immunocytochemical staining did not reveal any significant difference in the number of PR-immunoreactive neurons between frozen tissue compared with paraffin-embedded tissue. The results indicate that microwave irradiation can unveil PR antigenicity in sections of paraffin-embedded brain and enhances immunostaining in sections of frozen tissue.

Neuroendocrinology of the skin

The classical observations of the skin as a target for melanotropins have been complemented by the discovery of their actual production at the local level. In fact, all of the elements controlling the activity of the hypothalamus-pituitary-adrenal axis are expressed in the skin including CRH, urocortin, and POMC, with its products ACTH, alpha-MSH, and beta-endorphin. Demonstration of the corresponding receptors in the same cells suggests para- or autocrine mechanisms of action. These findings, together with the demonstration of cutaneous production of numerous other hormones including vitamin D3, PTH-related protein (PTHrP), catecholamines, and acetylcholine that share regulation by environmental stressors such as UV light, underlie a role for these agents in the skin response to stress. The endocrine mediators with their receptors are organized into dermal and epidermal units that allow precise control of their activity in a field-restricted manner. The skin neuroendocrine system communicates with itself and with the systemic level through humoral and neural pathways to induce vascular, immune, or pigmentary changes, to directly buffer noxious agents or neutralize the elicited local reactions. Therefore, we suggest that the skin neuroendocrine system acts by preserving and maintaining the skin structural and functional integrity and, by inference, systemic homeostasis.