Regulation of estrogen receptor alpha and beta expression by testosterone in the rat prostate gland

Morin hydrate ameliorates heat-induced testicular impairment in a mouse model

BACKGROUND

Heat stress is known to adversely affect testicular activity and manifest the pathogenesis of spermatogenesis. Morin hydrate is a plant-derived compound, which contains a wide range of biological activities. Thus, it is hypothesized that morin hydrate might have an ameliorative effect on heat-induced testicular impairment. There has not been any research on the impact of morin hydrate on heat-induced testicular damage.

METHODS

The experimental mice were divided into four groups, groups1 as the normal control group (CN), and the second which underwent heat stress (HS) by immersing the lower body for 15 min in a thermostatically controlled water bath kept at 43 °C (HS), and third and fourth heat-stressed followed by two different dosages of morin hydrate 10 mg/kg (HSM10) and 100 mg/kg (HSM100) for 14 days.

RESULTS

Morin hydrate treatment at 10 mg/kg improved, circulating testosterone levels (increases 3βHSD), and oxidative stress along with improvement in the testis and caput and corpus epididymis histoarchitecture, however, both doses of morin hydrate improved sperm parameters. Morin hydrate treatment significantly increases germ cell proliferation, (GCNA, BrdU staining), expression of Bcl2 and decreases expression of active caspase 3. Heat stress also decreased the expression of AR, ER- α, and ER-β, and Morin hydrate treatment increased the expression of these markers in the 10 mg/kg treatment group.

CONCLUSION

Morin hydrate ameliorates heat-induced testicular impairment modulating testosterone synthesis, germ cell proliferation, and oxidative stress. These effects could be manifested by regulating androgen and estrogen receptors. However, the two doses showed differential effects of some parameters, which requires further investigations.

The effect of nonylphenol exposure on the stimulation of melanomacrophage centers, estrogen and testosterone level, and ERα gene expression in goldfish

The present study tried to measure the formation of melanomacrophage centers (MMCs) in various organs of male and female goldfish exposed to nonylphenol (NP) and aimed to assess its relationship with the main sexual hormones, estrogen receptor expression, and the pigment content of the MMCs. Immature goldfish were exposed to 10^-6 and 10^-7 M NP for 25 days. After obtaining blood for measuring testosterone and estrogen (E2) levels, tissue samples were collected from various organs for histological studies, quantifying pigments using ImageJ software and chemical analysis, and measuring ERα gene expression. Results showed that the order of forming MMCs in various organs exposed to NP was liver > spleen > kidney, and the order of ERα gene expression was liver > testes > spleen > kidney in the male, and liver > spleen > kidney > ovaries in the female. Among the three pigments present in MMCs after exposure to the two doses of NP, melanin was more obvious (especially in the liver) and increased mostly in a dose-dependent manner in both sexes (especially in the male). Chemical analyses confirmed these results. Measurement of testosterone and E2 level in male and female goldfish showed that NP had more effect on the concentration of these hormones in male fish, indicating more endocrine-disrupting potential of NP against the male fish. Generally, the increase of melanin content of melanomacrophage centers coincided with the increase of ERα gene expression and decrease of testosterone level in goldfish after exposure to NP.

Prolactin promotes a partial recovery from the atrophy of both male and female gerbil prostates caused by castration

BACKGROUND

The male and female prostates are controlled by steroid hormones, suffering important morphological and physiological changes after castration. Prolactin is involved in the regulation of the male prostate, having already been identified in the tissue, acting through its receptor PRLR. In the Mongolian gerbil, in addition to the male prostate, the female prostate is also well developed and active in its secretion processes. The aim of the present study was to evaluate the effects of exposure to exogenous prolactin in the prostate of both intact and castrated male and female gerbils in order to establish if prolactin administration can sustain prostate cell activity in conditions of sexual hormone deprivation.

METHODS

The morphological analyses were performed by biometric analysis, lesion histological analysis and morphometric-stereological aspects. In addition, immune-cytochemical tests were performed for prolactin and its receptor, as well as for the receptors of androgen and oestrogen and serum prolactin dosage. All data were submitted to ANOVA or Kruskal-Wallis tests for comparison between groups. P < 0.05 was considered to be statistically significant.

RESULTS

The results showed a strong influence of prolactin on the morphology of the prostate, with the development of important epithelial alterations, after only 3 days of administration, and an expressive epithelial cell discard process after 30 days of administration. Prolactin acts in synergy with testosterone in males and mainly with oestrogens in females, establishing different steroid hormonal receptor immunoreactivity according to sex. It was also demonstrated that prolactin can assist in the recovery from some atrophic effects caused in the gland after castration, without causing additional tissue damage.

CONCLUSIONS

The prolactin and its receptor are involved in the maintenance of the homeostasis of male and female gerbils, and also cause distinct histological alterations after exogenous exposure for 3 and 30 days. The effects of prolactin are related to its joint action on androgens and oestrogens and it can also assist in the recovery from the atrophic effects of castration.

Delineating the regulation of estrogen and androgen receptor expression by sex steroids during rat spermatogenesis

Estrogen receptors (ERα and β) and androgen receptor (AR) regulate various critical processes during spermatogenesis. Since spermatogenesis is very sensitive to hormonal stimuli and perturbations, it is important to understand the regulation of expression of these receptors by sex steroid hormones. Although many studies have reported deregulation of steroid receptors on endocrine disruption, there is no consensus on the regulation of their expression by steroid hormones during spermatogenesis, and a lack of clear understanding of the mechanism of regulation. Here, we evaluated the receptor expressions in a well-established exogenous estradiol administration model. We then investigated the mechanisms by which the individual receptors regulate their expression by binding to the respective hormone response elements upstream of these receptor genes. By further employing in vitro and in vivo models of ER and AR stimulation or antagonism, we delineated their regulation in a receptor subtype-specific manner. Our results indicate that ERα positively regulates expression of both the ERs; whereas, ERβ and AR negatively regulate expression of both ERβ and AR by direct binding to upstream regulatory regions. The perturbations in the levels of steroid receptors could be an important factor contributing to spermatogenic defects and male sub-fertility after estradiol and ER agonist treatment. Our study delineates the direct contribution of the individual steroid receptors in the regulation of their own expression.

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Modifications of Western-type diet regarding protein, fat and sucrose levels as modulators of steroid metabolism and activity in liver

The aim of the study was to evaluate whether the modification of the Western-type diet (high-fat, high-sucrose diet rich in saturated fatty acids) considering macronutrients content would influence hepatic metabolism and activity of steroids. For 3 weeks Wistar rat were fed the Western-type diet (21% fat, 35% sucrose, 19% protein, lard) and its modifications regarding dietary protein (10 and 19%), fat (5 and 21%) and sucrose (0 and 35%) levels. The steroid 5α-reductase type 1 (Srd5a1) and androgen receptor (Ar) gene expression as well as testosterone (T) conversion towards 5α-reduced derivatives in liver were positively correlated with body weight gain. The Western-type diets with decreased protein content regardless of the sucrose level exerted the most negative effect on the antioxidant system decreasing catalase (Cat), sodium dismutase (Sod1) and glutathione peroxidase (Gpx1) gene expression as well as Cat and Gpx activity and total antioxidant status, simultaneously intensifying lipid peroxidation. The impaired antioxidant system was accompanied by decreased level of hepatic T metabolism towards estrogens: 17β-estradiol (E2) and estriol, and increased estrogen receptor type 1 (Esr1) gene expression. Liver Esr1 mRNA level was differently correlated with T (positively) and E2 (negatively) plasma levels. Whereas the fat reduction in Western-type diet restored the plasma proportion between T and E2. In conclusion it could be stated that Western-type diet modification relating to protein, sucrose and fat content can influence hepatic steroid metabolism and activity; however the estrogens and androgens metabolism in liver would be connected with impairment of liver function or catabolic activity, respectively.

Testosterone may increase rat anterior cruciate ligament strength

BACKGROUND

Women are more likely than men to injure the anterior cruciate ligament (ACL). Human and animal trials have linked circulating estradiol to injury rate and ligament strength. Fewer studies have examined the role of testosterone. The purpose of this study was to determine if male rats with normal testosterone levels would have stronger ACLs than castrated rats.

METHODS

Eight castrated (group C) and eight normal (group N) 12-week-old, male Sprague-Dawley rats were used for the study. Mean testosterone levels were 0.14ng/mL (95% CI: 0.10 to 0.17) in group C and 3.54ng/mL (95% CI: 1.32 to 5.76) in group N. After euthanasia, ACL cross-sectional area was calculated, and a servohydraulic material testing unit was used to measure ligament properties.

RESULTS

Specimens from both groups had similar cross-sectional area, but N specimens showed greater mean load-to-failure (34.5N [95% CI: 31.6 to 37.4] vs 29.2N [95% CI: 27.9 to 30.6]) and ultimate stress (38.7MPa [95% CI: 34.1 to 43.3] vs 31.8MPa [95% CI: 29.8 to 33.8]). Mean energy was 27.7mJ (95% CI: 23.1 to 32.2) in the N group and 23.4mJ (95% CI: 18.2 to 28.6) in the C group.

CONCLUSIONS

Rats with normal circulating testosterone had higher ACL load-to-failure and ultimate stress, indicating that testosterone may influence ACL strength and the injury rate of the ligament.

Increase in prostate stem cell antigen expression in prostatic hyperplasia induced by testosterone and 17β-estradiol in C57BL mice

Estradiol (E2) is known to act synergistically with testosterone (T) for the development of prostatic hyperplasia in rats and dogs, but murine prostate is less responsive to hormonal stimulation. However, a recent study revealed that the combined administration of E2 and T induced prostatic hyperplasia with bladder outlet obstruction in C57BL mice. To understand the mechanisms underlying the hormonal induction of prostatic hyperplasia, the expression of growth factors and their receptors, androgen receptor, estrogen receptor (ER), and prostatic secretory proteins was investigated. Ten-week-old male C57BL mice were treated with T (30mg) or T+E2 (0.5mg) for 10 weeks, and prostatic lobes were dissected and subjected to quantitative RT-PCR and immunoblotting analysis. T administration appeared to induce glandular prostatic growth, while with T+E2 administration this growth was greater and accompanied by extreme bladder enlargement. The expression of prostate stem cell antigen (PSCA) mRNA and protein was increased in prostate tissue in the T group. The combined administration of E2 with T prominently enhanced PSCA expression, along with increased insulin growth factor 1 mRNA levels and decreased estrogen receptor β mRNA expression. The synergistic effect of E2 on the expression of PSCA suggests that this protein may play an important role in the hormone-induced development of prostatic hyperplasia.

Sex Hormones and Tendon

The risk of overuse and traumatic tendon and ligament injuries differ between women and men. Part of this gender difference in injury risk is probably explained by sex hormonal differences which are specifically distinct during the sexual maturation in the teenage years and during young adulthood. The effects of the separate sex hormones are not fully elucidated. However, in women, the presence of estrogen in contrast to very low estrogen levels may be beneficial during regular loading of the tissue or during recovering after an injury, as estrogen can enhance tendon collagen synthesis rate. Yet, in active young female athletes, physiological high concentration of estrogen may enhance the risk of injuries due to reduced fibrillar crosslinking and enhanced joint laxity. In men, testosterone can enhance tendon stiffness due to an enhanced tendon collagen turnover and collagen content, but testosterone has also been linked to a reduced responsiveness to relaxin. The present chapter will focus on sex difference in tendon injury risk, tendon morphology and tendon collagen turnover, but also on the specific effects of estrogen and androgens.

The influence of sex hormones on anterior cruciate ligament rupture: female study

PURPOSE

The purpose of this study was to determine the difference in the concentrations of testosterone, 17-β estradiol and progesterone between female patients with and without ACL rupture and the possible effect of these hormones on generalised joint laxity.

METHODS

Female subjects with non-contact knee joint injury were included in this study. They were divided into two groups: the examined group, consisting of female subjects with ACL rupture, and the control group, consisting of female patients without ACL rupture. In the next step, the patients from these two groups were paired off on the basis of three factors: the level of professional sports involvement (including the type of sports activity), the side of the body where the injury had occurred (left or right) and the age of the subjects. In the end, there were 12 pairs (24 subjects). The concentrations of sex hormones were established from saliva specimens with the aid of the Salimetrics enzyme immunoassay. Generalised joint laxity was tested with the aid of the "laxity score" according to Beighton, Solomon and Soskolne.

RESULTS

Female subjects with ACL rupture had significantly lower concentrations of testosterone (p < 0.01), significantly lower concentrations of 17-β estradiol (p < 0.05) and significantly lower concentrations of progesterone (p < 0.01) than female subjects with intact ACL.

CONCLUSIONS

Decreased concentrations of testosterone, 17-β estradiol or progesterone may be a risk factor leading to ACL rupture. The concentrations of these hormones do not affect generalised joint laxity. Additional research on a larger group of patients is necessary to further determine the effects of these hormones on generalised joint laxity and ACL ruptures. Young female athletes with lower concentrations of sex hormones are more prone to anterior cruciate ligament rupture which is why they need to reduce their sports activities during the pre-ovulatory phase of the menstrual cycle, when these concentrations are additionally reduced.

Testosterone reduces knee passive range of motion and expression of relaxin receptor isoforms via 5α-dihydrotestosterone and androgen receptor binding

Ovarian steroids such as estrogen and progesterone have been reported to influence knee laxity. The effect of testosterone, however, remains unknown. This study investigated the effect of testosterone on the knee range of motion (ROM) and the molecular mechanisms that might involve changes in the expression of relaxin receptor isoforms, Rxfp1 and Rxfp2 in the patella tendon and lateral collateral ligament of the female rat knee. Ovariectomized adult female Wistar rats received three days treatment with peanut oil (control), testosterone (125 and 250 μg/kg) and testosterone (125 and 250 μg/kg) plus flutamide, an androgen receptor blocker or finasteride, a 5α-reductase inhibitor. Duplicate groups received similar treatment however in the presence of relaxin (25 ng/kg). A day after the last drug injection, knee passive ROM was measured by using a digital miniature goniometer. Both tendon and ligament were harvested and then analysed for protein and mRNA expression for Rxfp1 and Rxfp2 respectively. Knee passive ROM, Rxfp1 and Rxfp2 expression were significantly reduced following treatment with testosterone. Flutamide or finasteride administration antagonized the testosterone effect. Concomitant administration of testosterone and relaxin did not result in a significant change in knee ROM as compared to testosterone only treatment; however this was significantly increased following flutamide or finasteride addition. Testosterone effect on knee passive ROM is likely mediated via dihydro-testosterone (DHT), and involves downregulation of Rxfp1 and Rxfp2 expression, which may provide the mechanism underlying testosterone-induced decrease in female knee laxity.

Lack of anti-androgenic effects of equol on reproductive neuroendocrine function in the adult male rat

Equol (EQ), a metabolite of the soy isoflavone daidzein, has well known estrogenic properties. Data from animal studies suggested that EQ may act also as an anti-androgen. However, data regarding how EQ may affect brain functions like the regulation of neuroendocrine activity and reproductive outcomes in adult male rats are still lacking. We therefore investigated the effects of EQ on sex-steroid regulated gene expression in the brain [medial preoptic area/anterior hypothalamus (MPOA/AH) and medial basal hypothalamus/median eminence (MBH/ME)], pituitary, and prostate as a reference androgen-dependent organ. Furthermore reproductive outcomes were evaluated. The anti-androgen flutamide (FLUT) served as reference compound. Male rats (n=12 per group) were treated by gavage for 5 days with either EQ (100 or 250 mg/kgBW/day), or FLUT 100 mg/kgBW/day. All vehicle- and EQ-treated males showed successful reproductive outcomes, whereas FLUT-exposed males had severe reproductive impairments resulted in infertility. FLUT decreased relative weights of prostate, seminal vesicles and epididymides, and increased serum levels of luteinizing hormone, follicle-stimulating hormone, testosterone and 5α-dihydrotestosterone without altering prolactin levels, whereas EQ exerted opposite effects. Both EQ and FLUT decreased gonadotropin releasing hormone (GnRH) expression in the MPOA/AH. Only FLUT upregulated levels of GnRH receptor expression both in the MBH/ME and pituitary. While EQ downregulated the hypothalamic ERα and ERβ expressions, but FLUT did not. In the prostate, only FLUT upregulated both ERα and AR mRNA expression levels. Taken together, our findings are the first data that EQ did not induce anti-androgenic effects on brain, prostate and male reproductive parameters, however, estrogenic neuroendocrine and reproductive effects of EQ were observed.

Induction of paclitaxel resistance by ERα mediated prohibitin mitochondrial-nuclear shuttling

Paclitaxel is a drug within one of the most promising classes of anticancer agents. Unfortunately, clinical success of this drug has been limited by the insurgence of cellular resistance. To address this, Paclitaxel resistance was modeled in an in vitro system using estrogen treated prostate cancer cells. This study demonstrates that emerging resistance to clinically relevant doses of Paclitaxel is associated with 17-β-estradiol (E2) treatment in PC-3 cells, but not in LNCaP cells. We found that small interfering RNA mediated knockdown of ERα lead to a decrease in E2 induced Paclitaxel resistance in androgen-independent cells. We also showed that ERα mediated the effects of estrogen, thereby suppressing androgen-independent cell proliferation and mediating Paclitaxel resistance. Furthermore, E2 promoted Prohibitin (PHB) mitochondrial-nucleus translocation via directly mediation of ERα, leading to an inhibition of cellular proliferation by PHB. Additionally, restoration of Paclitaxel sensitivity by ERα knockdown could be overcome by PHB overexpression and, conversely, PHB knockdown decreased E2 induced Paclitaxel resistance. These findings demonstrate that PHB lies downstream of ERα and mediates estrogen-dependent Paclitaxel resistance signaling cascades.

Effects of exposure to estradiol and estradiol plus testosterone on the Mongolian gerbil (Meriones unguiculatus) female prostate

The female prostate is a differentiated organ found in several mammal species, including humans and rodents. This gland has been related to important functions on female reproductive biology. Although the factors, which regulate prostate's development and activity are not well known, its functionality has been related to steroid hormones. It is well established that cyclic changes of estradiol and progesterone levels promote histophysiological adaptations of the whole female body. In contrast, only a few is found about those adaptations in female prostate. Thus, this study aimed to evaluate the effect of estradiol and estradiol + testosterone association on gerbil female prostate in order to verify, which hormonal associations are necessary to its homeostasis. For this, adult females had the ovaries surgically removed. After recovering, they received estradiol and estradiol + testosterone doses through 30 days, each 48 h. The prostatic tissue underwent morphological and morphometric-estereological analysis. Hormonal restriction caused great gland involution and decreased secretory activity, aspects that were reverted by exposure to estradiol and estradiol + testosterone. However, these hormones were not able to re-establish the normal prostate histoarchitecture. The immunoreaction of steroid receptors (ER-α, ER-β, and AR) responded differently among the experimental and control groups, and PCNA assay showed a decrease in epithelial cell proliferation within groups that had hormone privation. Therefore, we conclude that estradiol and testosterone are able to influence prostate morphophysiology and the maintenance of gland homeostasis depends on a balance among these and other hormones.

The mouse as a model to investigate sex steroid metabolism in the normal and pathological prostate

Metabolism of sex steroids within the prostate is an important factor affecting its growth and pathology. Mouse models with genetic gain- and especially loss-of-function have characterised different steroid metabolic pathways and their contribution to prostate pathology. With reference to the human prostate, this review aims to summarize the steroidogenic pathways in the mouse prostate as the basis for using the mouse as a model for intraprostatic steroid signalling. In this review we summarize the current information for three main components of the steroid signalling pathway in the mouse prostate: circulating steroids, steroid receptors and steroidogenic enzymes with regard to signalling via androgen, estrogen, progesterone and glucocorticoid pathways. This review reveals many opportunities for characterisation steroid metabolism in various mouse models. The knowledge of steroid metabolism within prostate tissue and in a lobe (rodent)/region (human) specific manner, will give valuable information for future, novel hypotheses of intraprostatic control of steroid actions. This review summarizes knowledge of steroid metabolism in the mouse prostate and its relevance to the human.

Anterior prostate epithelial AR inactivation modifies estrogen receptor expression and increases estrogen sensitivity

Androgens influence prostate growth and development, so androgen withdrawal can control progression of prostate diseases. Although estrogen treatment was originally used to induce androgen withdrawal, more recently direct estrogen effects on the prostate have been recognized, but the nature of androgen-estrogen interactions within the prostate remain poorly understood. To characterize androgen effects on estrogen sensitivity in the mouse prostate, we contrasted models of castration-induced androgen withdrawal in the prostate stromal and epithelial compartments with a prostate epithelial androgen receptor (AR) knockout (PEARKO) mouse model of selective epithelial AR inactivation. Castration markedly increased prostate epithelial estrogen receptor (ER)α immunoreactivity compared with very low ERα expression in intact males. Similarly, strong basal and luminal ERα expression was detected in PEARKO prostate of intact males, suggesting that epithelial AR activity regulated epithelial ERα expression. ERβ was strongly expressed in intact, castrated, and PEARKO prostate. However, strong clusters of epithelial ERβ positivity coincided with epithelial stratification in PEARKO prostate. In vivo estrogen sensitivity was increased in PEARKO males, with greater estradiol-induced prostate growth and epithelial proliferation leading to squamous metaplasia, featuring markedly increased epithelial proliferation, thickening, and keratinization compared with littermate controls. Our results suggest that ERα expression in the prostate epithelial cells is regulated by local, epithelia-specific, androgen-dependent mechanisms, and this imbalance in the AR- and ER-mediated signaling sensitizes the mature prostate to exogenous estrogens.

Testosterone administration to adult rats differentially modulates androgen and oestrogen receptor-α expression in reproductive organs and pituitary

Regulation of androgen receptor (AR) and oestrogen receptor α (ERα) expression has direct bearing on the physiology of male reproductive organs. With the help of three independent tools of immunohistochemistry, western blotting and RT-PCR, AR and ER α receptor expression was examined in the testis, epididymis, prostate, seminal vesicle and pituitary of adult rats following testosterone enanthate (TE, 3 mg/100 μl of olive oil/rat per week) intervention for 15 and 30 days. TE administration reduced AR immunoexpression which coincided well with the decline in the receptor protein and transcript levels. In contrast, ERα was found overexpressed in all the organs. While weights of testis and epididymis decreased significantly, those of prostate, seminal vesicle and pituitary demonstrated an upward trend. Spermatogenesis was adversely affected with decline in number of germ cells per tubule and increased prevalence of germ cell apoptosis. Increase in serum and decrease in intra-testicular levels of testosterone were found significant (P < 0.001) in both 15 and 30 days treatment groups. Serum follicle stimulating hormone declined significantly (P < 0.001) at the end of 30 days treatment. Taken together, the above findings indicate that the testosterone intervention differentially modulates, AR ERα expression, which is associated with hypospermatogenesis and increased germ cell apoptosis.

Estrogen-regulated development and differentiation of the prostate

Both androgens and estrogens play a significant role in the prostate and are critical for normal prostate growth and development, as well as the maintenance of adult prostatic homeostasis throughout life. It is the balance of these two hormones, rather than each individually, that is important for prostatic development and differentiation. Estrogen action is mediated by the estrogen receptors, ERalpha and ERbeta. ERalpha is expressed throughout the prostatic tissue during fetal and early neonatal life, and if activated inappropriately, produces late-life disease, including inflammation and emergence of pre-malignant pathologies. In contrast, ERbeta expression is initiated after ERalpha, is localized primarily to the epithelium, and appears to be important during later periods of development such as puberty and adulthood, acting to regulate cellular proliferation and differentiation in the adult tissue. Therefore, there is also a spatial and temporal balance between ERalpha and ERbeta that is critical for development. Together with the shifting balance between androgens and estrogens themselves, the subtle, yet critical, balance between the activity of ERalpha and ERbeta is what ultimately determines the response of the prostate to estrogen, and is crucial for prostate health.

The role of estrogens and estrogen receptors in normal prostate growth and disease

Estrogens have significant direct and indirect effects on prostate gland development and homeostasis and have been long suspected in playing a role in the etiology of prostatic diseases. Direct effects are mediated through prostatic estrogen receptors alpha (ERalpha) and beta (ERbeta) with expression levels changing over time and with disease progression. The present review examines the evidence for a role of estrogens and specific estrogen receptors in prostate growth, differentiation and disease states including prostatitis, benign prostatic hyperplasia (BPH) and cancer and discusses potential therapeutic strategies for growth regulation via these pathways.

Sex steroid receptor expression profile in brown adipose tissue. Effects of hormonal status

Recent investigations suggest that sex hormones play an important role in the brown adipose tissue (BAT) thermogenic program by acting on several steps of the lipolytic signal cascade and on the UCP1 transcription control. However, the number of studies focusing on steroid receptor status in brown adipose tissue is negligible. In the present study, we analyze steroid receptor mRNA levels in brown adipose tissue in male and female rats and in pregnant and lactating females, all of them models with a different hormonal background. The direct effect of sex hormones on the expression of their receptors was studied in vitro in primary culture of brown adipocytes. Oestrogen receptor (ERalpha) and androgen receptor (AR) densities were higher in male than in female BAT. PR A+B mRNA expression was downregulated in lactation, suggesting a role of progesterone signalling in thermogenesis impairment at this stage. In vitro studies showed that progesterone decreased PR A+B mRNA and that testosterone downregulated ERalpha mRNA. The results highlighted in this study demonstrate the presence of steroid receptor mRNA in BAT and in brown cell cultured adipocytes, supporting the idea that changes in steroid receptor expression would be important for the understanding of sex hormone effects on BAT physiology.

5alpha-Androstane-3beta,17beta-diol (3beta-diol), an estrogenic metabolite of 5alpha-dihydrotestosterone, is a potent modulator of estrogen receptor ERbeta expression in the ventral prostrate of adult rats

Prostate is one of the major targets for dihydrotestosterone (DHT), however this gland is also recognized as a nonclassical target for estrogen as it expresses both types of estrogen receptors (ER), especially ERbeta. Nevertheless, the concentrations of aromatase and estradiol in the prostate are low, indicating that estradiol may not be the only estrogenic molecule to play a role in the prostate. It is known that DHT can be metabolized to 5alpha-androstane-3beta,17beta-diol (3beta-diol), a hormone that binds to ERbeta but not to AR. The concentration of 3beta-diol in prostate is much higher than that of estradiol. Based on the high concentration of 3beta-diol and since this metabolite is a physiological ERbeta ligand, we hypothesized that 3beta-diol would be involved in the regulation of ERbeta expression. To test this hypothesis, adult male rats were submitted to castration followed by estradiol, DHT or 3beta-diol replacement. ERbeta and AR protein levels in the prostate were investigated by immunohistochemistry and Western blotting assays. The results showed that after castration, the structure of the prostate was dramatically changed and ERbeta and AR protein levels were decreased. Estradiol had just minor effects on the parameters analyzed. DHT-induced partial recovery of ERbeta while it was the most effective inductor of AR expression. Replacement with 3beta-diol-induced the highest levels of ERbeta, but was comparatively less effective in recovering the AR expression and the gland structure. These results offer evidence that one functional role of 3beta-diol in the prostate may be autoregulation of its natural receptor, ERbeta.

Estrogen sensitivity of target genes and expression of nuclear receptor co-regulators in rat prostate after pre- and postnatal exposure to the ultraviolet filter 4-methylbenzylidene camphor

BACKGROUND AND OBJECTIVES

In previous studies, we found that the ultraviolet filter 4-methyl-benzylidene camphor (4-MBC) exhibits estrogenic activity, is a preferential estrogen receptor (ER)-beta ligand, and interferes with development of female reproductive organs and brain of both sexes in rats. Here, we report effects on male development.

METHODS

4-MBC (0.7, 7, 24, 47 mg/kg/day) was administered in chow to the parent generation before mating, during gestation and lactation, and to offspring until adulthood. mRNA was determined in prostate lobes by real-time reverse transcription-polymerase chain reaction and protein was determined by Western blot analysis.

RESULTS

4-MBC delayed male puberty, decreased adult prostate weight, and slightly increased testis weight. Androgen receptor (AR), insulin-like growth factor-1 (IGF-1), ER-alpha, and ER-beta expression in prostate were altered at mRNA and protein levels, with stronger effects in dorsolateral than ventral prostate. To assess sensitivity of target genes to estrogens, offspring were castrated on postnatal day 70, injected with 17beta-estradiol (E(2); 10 or 50 microg/kg, sc) or vehicle on postnatal day 84, and sacrificed 6 hr later. Acute repression of AR and IGF-1 mRNAs by E(2), studied in ventral prostate, was reduced by 4-MBC exposure. This was accompanied by reduced co-repressor N-CoR (nuclear receptor co-repressor) protein in ventral and dorsolateral prostate, whereas steroid receptor coactivator-1 (SRC-1) protein levels were unaffected.

CONCLUSIONS

Our data indicate that 4-MBC affects development of male reproductive functions and organs, with a lowest observed adverse effect level of 0.7 mg/kg. Nuclear receptor coregulators were revealed as targets for endocrine disruptors, as shown for N-CoR in prostate and SRC-1 in uterus. This may have widespread effects on gene regulation.

Reduced endogenous estrogen delays epididymal development but has no effect on efferent duct morphology in boars

The study presented herein was designed to test the hypothesis that reduced endogenous estrogen in the boar alters efferent duct morphology, epididymal morphology, and steroid receptor expression. Twenty-eight littermate pairs of boars were treated with Letrozole, an aromatase inhibitor, or with vehicle from 1 week of age until castration at 2 through 8 months. Efferent ducts and epididymides were examined for morphological development and steroid receptor expression. Efferent duct morphology was not different between control and Letrozole-treated animals at any examined age. Androgen receptor (AR), estrogen receptor α (ERα), and β (ERβ) were expressed in the epithelial cells of the efferent ducts at all ages; expression was similar in control and treated animals. Morphological development of the caput and corpus was delayed in Letrozole-treated animals, but this delay was transient since morphology was similar between control and treated animals at 8 months. The cauda did not show a delay in development, but was more developed in treated animals at 2 months. AR, ERα, and ERβ were expressed in all three epididymal regions; no difference was observed between control and treated animals. In summary, estrogen appears to be important for development of the epididymis; however, the cauda may be regulated differently than the caput and corpus. Results for the efferent ducts suggest that the normally high endogenous estrogens are not required for regulation of fluid reabsorption in the boar. It also suggests that any ER activation required for maintenance of efferent duct morphology and function is normal in Letrozole-treated boars.

Photoperiod affects estrogen receptor alpha, estrogen receptor beta and aggressive behavior

Estrogens have important effects on male and female social behavior. Despite growing knowledge of the anatomy and behavioral effects of the two predominant estrogen receptor subtypes in mammals (ERalpha and ERbeta), relatively little is known about how these receptors respond to salient environmental stimuli. Many seasonally breeding species respond to changing photoperiods that predict seasonal changes in resource availability. We characterized the effects of photoperiod on aggressive behavior in two species of Peromyscus that exhibit gonadal regression in short days. P. polionotus (old field mice) were more aggressive than P. maniculatus (deer mice) and both species were more aggressive in short days. We used immunocytochemistry and real-time polymerase chain reaction to characterize the effects of photoperiod on ERalpha and ERbeta expression. In both species ERalpha-immunoreactive staining in the posterior bed nucleus of the stria terminalis (BNST) was increased in short vs. long days. Both species had reduced ERbeta-immunoreactive expression in the posterior BNST in short days. In the medial amygdala ERbeta immunoreactivity was increased in long days for both species. Using real-time polymerase chain reaction on punch samples that included the BNST, we observed that ERalpha mRNA was increased and ERbeta mRNA was decreased in short days. These data suggest that the effects of photoperiod on ERalpha and ERbeta expression may thus have important behavioral consequences.

Quantitative determination of lobe specificity of mRNA expression of androgen-dependent genes in the rat prostate gland

The rodent prostate has a complex structure, consisting of a ventral prostate (VP), lateral prostate (LP), dorsal prostate (DP) and anterior prostate (AP), and most studies so far have focused on the VP. Androgen-responsive prostatic secretory proteins, such as prostatein and kallikreins, are mainly produced in the VP, but others are abundant in the LP and DP, though little is known about differences of androgen regulation among the different lobes. Here, the mRNA expression levels of some representative androgen-responsive genes, including those encoding prostatic secreted proteins, were quantitatively determined in each of the prostatic lobes of intact rats and castrated rats treated with testosterone alone or plus flutamide. The results show that the transcriptional regulation of prostatic secretory proteins differs greatly among lobes, generally being more tightly regulated in the VP. A number of growth factor mRNAs were differentially expressed in separate lobes and were regulated by testosterone in a lobe-specific manner. Lobe-specific regulation by androgen was also found for other genes, including the DAD-1 and calreticulin genes. Thus, hormone-dependent transcriptional regulation of prostate genes differs among lobes, and there is also interlobar diversity of basal mRNA expression levels.

Nongenomic responses to 17beta-estradiol in male rat mesenteric arteries abolish intrinsic gender differences in vascular responses

The aim of the present study was to investigate the gender differences in the acute effects of 17beta-estradiol on the rat superior mesenteric artery. Isometric tension was measured in rings of mesenteric arteries from both male and female Sprague-Dawley rats. Relaxation to acetylcholine was not significantly different between arteries (with endothelium) from male and female rats in the absence or presence of 17beta-estradiol. After blockade of endothelium-dependent hyperpolarizations with apamin (0.3 microM) plus charybdotoxin (0.1 microM), acute exposure to 17beta-estradiol (1 nM) for 30 min resulted in enhancement of relaxation to acetylcholine in arteries from male but not female rats. After acute exposure to 17beta-estradiol, mesenteric arteries from male rats were more sensitive to sodium nitroprusside than arteries from female rats. Contractions of mesenteric arteries to phenylephrine and 9,11-dideoxy-11alpha,9alpha-epoxymethanoprostaglandin F(2alpha) (U46619) were greater in arteries from male rats than female rats. This difference was not detected after acute exposure to 17beta-estradiol. In preparations without endothelium, the enhancement of relaxation and reduction in contraction in arteries from male rats were preserved. These results suggest that there exists a gender difference in the response to the acute nongenomic modulatory effect of 17beta-estradiol in rat mesenteric arteries. Arteries from male rats seem to be more sensitive to the modulatory effects of 17beta-estradiol than arteries from female rats. The effect appears to be mainly at the level of the vascular smooth muscles.

Hormone profiles after intramuscular injection of testosterone enanthate in patients with hypogonadism

To examine hormone levels after androgen replacement therapy (ART) in Japanese male patients with hypogonadism, nine Japanese male patients with hypogonadism (serum total testosterone (tT) or free testosterone (fT) levels of < or = 2.7 ng/mL or < or = 10 pg/mL, respectively; average age, 59 years) were enrolled. They were treated with 125 mg of testosterone enanthate by single intramuscular injection. Blood samples were collected on the morning of the day of treatment, pre-ART, as well as on days 1 to 7 and day 14 after administration. Serum levels of tT, fT, estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and sex hormone-binding globulin (SHBG) were determined. On day 1 after administration, the mean serum levels of tT and fT were 7.62 ng/mL and 23.22 pg/mL, respectively. Serum levels of tT and fT on day 14 after administration were lower than their pre-ART values. One patient exhibited abnormally high serum tT and fT levels of 19.6 ng/mL and 44.4 pg/mL, respectively. Serum levels of LH and FSH began to decrease gradually on day 5 after administration. Serum levels of SHBG did not change throughout the observation period. Serum levels of E2 increased 1.7 times on day 1 after administration but returned to its pre-ART value by day 14 after administration. The dose of testosterone enanthate for male patients with hypogonadism requiring ART should be determined carefully because some patients exhibited high serum levels of androgen beyond the physiological range and gonadotropin was suppressed in all treated patients.

Metastases of prostate cancer express estrogen receptor-beta

OBJECTIVES

To examine estrogen receptor-beta (ERbeta) expression in prostate cancer (CaP) metastases, thereby providing a basis for conducting estrogen therapy studies in patients with metastatic CaP. Advanced androgen-independent CaP is a serious health problem with no effective treatment at present. Estrogens have been reported to inhibit the growth of CaP cells in androgen-free environments. Recent reports have shown that the prostatic epithelium and primary CaP cells express ERbeta, with decreased expression of ERbeta accompanying CaP progression. It has been proposed that ERbeta may play a role in the growth regulation of prostate cells. The targeting of ERs by selective ER modulators might be an effective method of treating advanced CaP.

METHODS

The anti-ERbeta antibody GC17 was used in immunohistochemistry to characterize the expression of ERbeta in CaP metastasis specimens (n = 60) obtained from 20 patients who had died of CaP. Statistical analyses were performed to evaluate the association of ERbeta expression with clinical parameters, including prostate-specific antigen levels, radiotherapy, and estrogen exposure.

RESULTS

Nuclear ERbeta staining was detected in all bone CaP metastases (33 of 33) and nonosseous CaP metastases (27 of 27). However, a large variability in the percentage of immunoreactive cells (5% to 100%) was found among patients, as well as among individual patient samples. A statistically significant negative association between nuclear ERbeta staining and estrogen exposure (P = 0.05) was detected.

CONCLUSIONS

Our data have shown that ERbeta is expressed in CaP metastases, validating the initiation of studies to evaluate selective ER modulators for treatment of advanced CaP.

Effects of estradiol-17β, testosterone and a black cohosh preparation on bone and prostate in orchidectomized rats

Estradiol (E2) and testosterone (T) effectively prevent orchidectomy (orx) induced osteoporosis. T, however, stimulates prostate proliferation which may lead to malignancy. We showed that a Cimicifuga racemosa (CR) preparation had bone-sparing effects without exerting estrogenic effects in the uterus. We studied therefore whether a CR preparation has also antiosteoporotic effects in orx rats substituted with E2, T or CR via pelleted food over a period of 3 months. Average daily intake per animal was: T: 25 mg; E2: 0.325 mg, CR low dose: 33 mg; CR high dose: 133 mg. E2, T and CR at the high dose partially prevented development of osteoporosis as measured by quantitative computer tomography in the metaphysis of the tibia. E2, but not T or CR reduced serum osteocalcin and the metabolic products of collagen-1alpha1. Gene expression of collagen-1alpha1 and tartrate-resistant acid phosphatase was decreased by E2 and the higher dose of the CR extract but increased in the T-treated animals. In the prostate T inhibited androgen receptor, estrogen receptor alpha and insulin-like growth factor-1 gene expression but stimulated the expression of the ERbeta gene. These effects were not shared by E2 or both doses of the CR extract. It is concluded that E2, T and CR exert antiosteoporotic effects in the metaphysis of the tibia of orx rats. T has profound effects in the prostate which were not seen in the E2- and CR-treated animals. Therefore, the Cimicifuga racemosa extract BNO 1055 may be useful to prevent osteoporosis in aged male patients with reduced testosterone production.

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.

Estrogen receptor alpha and imprinting of the neonatal mouse ventral prostate by estrogen

Exposure to estrogen in the neonatal period affects prostatic growth and leads to an increased incidence of prostatic intraepithelial neoplasia in later life. The effects of neonatal estrogen are clearly dependent on estrogen receptor (ER) alpha because they do not occur in ERalpha-knockout mice. Because ERalpha is expressed in the stroma, but not in the epithelium, of the adult ventral prostate, the concept of indirect estrogen effects through stromal signaling has been proposed. Here, we show that during the first 4 weeks of life, there are profound and rapid changes in the ER profile in the mouse ventral prostate. ERalpha is abundant in the stroma during week 1, but by week 2 it is exclusively epithelial, and then by week 4, ERalpha is lost and ERbeta is dominant in the prostatic epithelium. The presence of ERalpha is associated with a high proliferation index, and ERbeta is associated with quiescence. Branching morphogenesis was altered in ERalpha-/-, but not in ERbeta-/-, mice. We conclude that imprinting and branching morphogenesis of the ventral prostate are mediated by estrogen acting directly on epithelial and stromal ERalpha during the first 2 weeks of life.

Estrogen enhancement of androgen-responsive gene expression in hormone-induced hyperplasia in the ventral prostate of F344 rats

It has been postulated that, in addition to the crucial role of androgens, estrogens may be involved in development of prostate hyperplasia and cancer. In rats, combined administration of estrogen and androgen synergistically increases ventral prostate weight, and continued treatment results in the development of glandular hyperplasia. Prostate adenocarcinoma can be induced by chemical carcinogens in rats, and estrogen given together with an androgen generally shortens the latent period or increases the incidence and/or multiplicity of carcinomas. However, the mechanisms responsible for these synergistic effects of estrogen and androgen are poorly understood. In the present study, we examined the combined effects of 17beta-estradiol (E2) and testosterone (T) on gene expression in an early stage of prostate hyperplasia in an F344 rat model. ERalpha expression, which has been suggested to contribute to development of prostatic hyperplasia, was increased by the combined treatment with T and E2, while it was suppressed by T alone. Expression levels of two androgen-responsive genes, probasin and kallikrein S3, were increased in the ventral prostate of rats treated with T plus E2 for 4 weeks in a dose-dependent manner, while short-term treatment did not alter the expression. These results suggested that enhancing effects of E2 on transcription of androgen-responsive genes, as well as an increased level of ERalpha may play roles in the synergistic effects of E2 on T-induced prostate hyperplasia.

Effects of vitamin supplementation on PCB (Aroclor 1254)-induced changes in ventral prostatic androgen and estrogen receptors

The objective of this study was to determine the impact of the polychlorinated biphenyl (PCB) Aroclor 1254 and vitamin C and E on ventral prostatic testosterone and estradiol receptor concentration. A group of 30 rats were treated with Aroclor 1254 [2 mg/kg body weight (bwt) /day/ip] for 30 days; 10 rats were treated as Aroclor 1254 control. The remaining 20 rats were subdivided into the following two subgroups of 10 animals each. One group was given vitamin C (500 mg/kg bwt/day/oral) for 10 days, whereas the other group was given vitamin E (50 mg/kg bwt/day/oral) for 10 days. Separate controls were also maintained. Ventral prostatic androgen and estrogen receptor concentration in all the groups were quantified. Serum hormonal profiles such as total T3, T4, TSH, testosterone, and estradiol were also estimated in all the groups. Ventral prostatic zinc content and serum zinc concentration were also determined in all the groups. Aroclor 1254 exposure decreased the concentration of both receptors. Decreased serum total T3, T4, testosterone, estradiol, and increased TSH were observed after Aroclor 1254 exposure. Serum and tissue zinc levels were also decreased. Administration of vitamin C or E restored both the receptor concentration and the serum hormone levels with the exception of estradiol. Administration of vitamin C or E restored zinc levels. Vitamin E was more sensitive on ventral prostatic androgen receptors and zinc levels, including serum, in PCB-exposed rats.