Role of 17β-estradiol and testosterone in apoptosis

The Role of Sex Steroid Hormones in the Association Between Manganese Exposure and Bone Mineral Density: National Health and Nutrition Examination Survey 2013-2018

This study investigates the association between blood Mn and bone mineral density (BMD), focusing on the mediating role of sex steroids, using data from 8617 participants in the National Health and Nutrition Examination Survey (NHANES) 2013-2018. Weighted multiple linear regression models were used to examine the association of blood Mn and total BMD, and mediation analyses were used to explored the roles of total testosterone (TT), estradiol (E2), and sex hormone-binding globulin (SHBG) in the Mn-BMD relationship, stratified by sex and menopausal status. Blood Mn was negatively associated with BMD in both sexes, with a pronounced effect in postmenopausal women. SHBG mediated 37.16% of the Mn-BMD association in men, whereas no mediating effects were found in women. E2 exhibited a significant indirect effect, suggesting that reduced E2 levels may amplify Mn's effect on BMD. These findings indicate that Mn exposure is associated with decreased BMD, potentially through alterations in sex steroids, highlighting the importance of considering hormone status when evaluating the impact of Mn exposure on BMD.

The impact of neonicotinoid pesticides on reproductive health

Neonicotinoids are some of the most widely used insecticides in the world because they broadly target chewing and sucking insects. Neonicotinoids are used in commercial agricultural systems, sold for use in home gardens, and found in veterinary pharmaceuticals in the form of flea and tick preventatives for companion animals. They are also used as crop seed treatments and spread throughout crops as they mature. As a result, humans, wildlife, livestock, and pets are routinely exposed to neonicotinoids through the consumption of contaminated food and water as well as through the use of some veterinary pharmaceuticals. Although several studies indicate that neonicotinoid exposure causes genotoxicity, neurotoxicity, hepatotoxicity, and immunotoxicity in some non-target species, the impact of neonicotinoid pesticides on the male and female reproductive systems in mammals is largely understudied. This review summarizes current insights on the impact of common neonicotinoid pesticides such as acetamiprid, clothianidin, imidacloprid, and thiacloprid on male and female reproductive health in mammals. The review also summarizes the impacts of exposure to mixtures of neonicotinoids on reproductive endpoints. In addition, this review highlights where gaps in research on neonicotinoid pesticides and reproductive health exist so that future studies can be designed to fill current gaps in knowledge.

Reduced 17β-estradiol following ovariectomy induces mitochondrial dysfunction and degradation of synaptic proteins in the entorhinal cortex

Reductions in circulating estrogens can contribute to cognitive decline, in part by impairing mitochondrial function within the hippocampal region. The entorhinal cortex provides the hippocampus with its main cortical inputs. To assess the impact of estrogen deficiency on mitochondrial respiration and synaptic proteins in the entorhinal cortex, female wildtype rats received either sham surgery, bilateral ovariectomy, or ovariectomy with implantation of a subdermal capsule to maintain low levels of circulating 17β-estradiol (E2). Mitochondrial respiration in the entorhinal cortex was not significantly affected two weeks following ovariectomy, but there was a reduction in oxygen consumption four weeks after ovariectomy that was prevented by E2 supplementation. The expression of mitochondrial membrane integrity element voltage-dependent anion channel protein (VDAC1) was also reduced four weeks after ovariectomy, suggesting that respiration was reduced due to a decline in mitochondrial density. Ovariectomy also increased mitochondrial and cytoplasmic cytochrome c and upregulated superoxide dismutase 2 (SOD2) both two and four weeks after ovariectomy, reflecting mitochondrial electron leakage and oxidative redox imbalance. Further, the ovariectomy-induced changes in mitochondrial proteins were associated with reductions in postsynaptic density protein 95 (PSD95) and the presynaptic protein synaptophysin. There were no changes in mitochondrial or synaptic proteins in ovariectomized animals that received E2 supplementation. Our findings indicate that reductions in circulating 17β-estradiol induced by ovariectomy disrupt mitochondrial functions in the entorhinal cortex, and suggest that a resulting increase in oxidative stress contributes to the degradation in synaptic proteins that may affect cognitive functions mediated by the hippocampal region.

In vitro endocrine and cardiometabolic toxicity associated with artificial turf materials

Artificial turf, a consumer product growing in usage in the United States, contains diverse chemicals, some of which are endocrine disruptive. Endocrine effects from turf material extracts have been primarily limited to one component, crumb rubber, of these multi-material products. We present in vitro bioactivities from non-weathered and weathered turf sample extracts, including multiple turf components. All weathered samples were collected from real-world turf fields. Non-weathered versus weathered differentially affected the androgen (AR), estrogen (ER), glucocorticoid (GR), and thyroid receptors (TR) in reporter bioassays. While weathered extracts more efficaciously activated peroxisome proliferator activated receptor γ (PPARγ), this did not translate to greater in vitro adipogenic potential. All turf extracts activated the aryl hydrocarbon receptor (AhR). High AhR-efficacy extracts induced modest rat cardiomyoblast toxicity in an AhR-dependent manner. Our data demonstrate potential endocrine and cardiometabolic effects from artificial turf material extracts, warranting further investigation into potential exposures and human health effects.

mTOR and SGLT-2 Inhibitors: Their Synergistic Effect on Age-Related Processes

The aging process contributes significantly to the onset of chronic diseases, which are the primary causes of global mortality, morbidity, and healthcare costs. Numerous studies have shown that the removal of senescent cells from tissues extends lifespan and reduces the occurrence of age-related diseases. Consequently, there is growing momentum in the development of drugs targeting these cells. Among them, mTOR and SGLT-2 inhibitors have garnered attention due to their diverse effects: mTOR inhibitors regulate cellular growth, metabolism, and immune responses, while SGLT-2 inhibitors regulate glucose reabsorption in the kidneys, resulting in various beneficial metabolic effects. Importantly, these drugs may act synergistically by influencing senescence processes and pathways. Although direct studies on the combined effects of mTOR inhibition and SGLT-2 inhibition on age-related processes are limited, this review aims to highlight the potential synergistic benefits of these drugs in targeting senescence.

Testosterone, β-estradiol, and hepatocellular carcinoma: stimulation or inhibition? A comparative effect analysis on cell cycle, apoptosis, and Wnt signaling of HepG2 cells

Unlike breast and prostate cancers, which are specifically affected by estrogens or androgens, hepatocellular carcinoma has been reported to be influenced by both sex hormones. Given the coincidental differences of hepatocellular carcinoma in men and women, we investigated the effects of β-estradiol and testosterone on the cell cycle, apoptosis, and Wnt signaling in a model of hepatocellular carcinoma to understand the sex hormone-related etiology. To determine the effective concentration of both hormones, an MTT assay was performed. The effects of β-estradiol and testosterone on cell proliferation and death were evaluated by specific staining and flow cytometry. In addition, gene expression levels of estimated factors involved in GPC3-Wnt survival signaling were analyzed using quantitative real-time polymerase chain reaction. Both hormones inhibited hepatic cell proliferation through arresting the cell cycle at S/G2 and increased the apoptosis rate in HepG2 cells. Both hormones dose-dependently decreased GPC3, Wnt, and DVL expression levels as activators of the Wnt-signaling pathway. In the case of Wnt-signaling inhibitors, the effects of both hormones on WIF were negligible, but they increased DKK1 levels in a dose-dependent manner. In each of the effects mentioned above, β-estradiol was notably more potent than testosterone. In contrast to the primary hypothesis of the project, in which testosterone was considered a stimulating carcinogenic factor in HCC pathogenesis, testosterone inhibited the occurrence of HCC similarly to β-estradiol. However, this inhibitory effect was weaker than that of β-estradiol and requires further study.

5 mC modification of steroid hormone biosynthesis-related genes orchestrates feminization of channel catfish induced by high-temperature

To elucidate the mechanism behind channel catfish feminization induced by high temperature, gonad samples were collected from XY pseudo-females and wild-type females and subjected to high-throughput sequencing for Whole-Genome-Bisulfite-Seq (WGBS) and transcriptome sequencing (RNA-Seq). The analysis revealed 50 differentially methylated genes between wild-type females and XY pseudo-females, identified through the analysis of KEGG pathways and GO enrichment in the promoter of the genome and differentially methylated regions (DMRs). Among these genes, multiple differential methylation sites observed within the srd5a2 gene. Repeatability tests confirmed 7 differential methylation sites in the srd5a2 gene in XY pseudo-females compared to normal males, with 1 specific differential methylation site (16608174) distinguishing XY pseudo-females from normal females. Interestingly, the expression of these genes in the transcriptome showed no difference between wild-type females and XY pseudo-females. Our study concluded that methylation of the srd5a2 gene sequence leads to decreased expression, which inhibits testosterone synthesis while promoting the synthesis of 17β-estradiol from testosterone. This underscores the significance of the srd5a2 gene in the sexual differentiation of channel catfish, as indicated by the ipu00140 KEGG pathway analysis.

Effect of estrogens on apoptosis in the pituitary of viscachas (Lagostomus maximus maximus)

Estrogens, acting through their receptors (ERα and ERβ), regulate cell turnover in the pituitary gland, influencing cell proliferation and apoptosis across various species. However, their role in pituitary processes in seasonally reproducing animals remains poorly understood. This study aims to investigate the influence of estrogens, through the expression of their specific receptors, on the apoptosis of PD cells in relation to sexual maturity, the reproductive cycle, and pregnancy in a seasonal reproductive rodent (Lagostomus maximus maximus). ERα and caspase-3-cleaved (CASP3c) immunoreactive (-ir) cells were identified through immunohistochemistry. Apoptotic cells were detected using the TUNEL technique, with quantitative analysis facilitated by image analysis software, alongside measurement of serum estradiol levels using radioimmunoassay The immunostaining pattern for ERα included nuclear (ERαn) and cytoplasmic (ERαc) staining. In male viscachas, ERα expression significantly increases from immature to adult animals, correlating with the rise in serum estradiol levels and a decrease in the percentage of apoptotic cells. During the gonadal regression period in adult males, a decrease in the number of ER-ir cells and serum levels of estradiol corresponds with an increase in the number of apoptotic cells. In females, serum levels of estradiol peaked during mid-pregnancy, coinciding with a significant decrease in the number of apoptotic cells in the PD. Simultaneously, the percentage of ERαn-ir cells reaches its maximum value during late pregnancy, indicating the need to maintain the protective action of this gonadal hormone throughout the extensive pregnancy in these rodents. Regional ERα receptor expression and apoptotic cells appear to be associated with distinct PD cell populations and their hormonal responses. Finally, elevated estradiol levels coincide with diminished apoptotic cells in the male reproductive cycle and during pregnancy, suggesting an antiapoptotic role of estradiol in this species.

The nongenomic neuroprotective effects of estrogen, E2-BSA, and G1 following traumatic brain injury: PI3K/Akt and histopathological study

OBJECTIVES

Studies suggest that both genomic and nongenomic pathways are involved in mediating the salutary effects of steroids following traumatic brain injury (TBI). This study investigated the nongenomic effects of 17β-estradiol (E2) mediated by the PI3K/p-Akt pathway after TBI.

METHODS

Ovariectomized rats were apportioned to E2, E2-BSA (E2 conjugated to bovine serum albumin), G1 [G-protein-coupled estrogen receptor agonist (GPER)] or their vehicle was injected following TBI, whereas ICI (classical estrogen receptor antagonist), G15 (GPER antagonist), ICI + G15, and their vehicles were injected before the induction of TBI and injection of drugs. Diffuse TBI was induced by the Marmarou model. Evans blue (EBC, 5 h), brain water contents (BWC), histopathological changes, and brain PI3K and p-Akt protein expressions were measured 24 h after TBI. The veterinary comma scale (VCS) was assessed before and at different times after TBI.

RESULTS

The results showed a reduction in BWC and EBC and increased VCS in the E2, E2-BSA, and G1 groups. Also, E2, E2-BSA, and G1 reduced brain edema, inflammation, and apoptosis. The ICI and G15 inhibited the beneficial effects of E2, E2-BSA, and G1 on these parameters. All drugs, following TBI, prevented the reduction of brain PI3K/p-Akt expression. The individual or combined use of ICI and G15 eliminated the beneficial effects of E2, E2-BSA, and G1 on PI3K/p-Akt expressions.

CONCLUSIONS

These findings indicated that PI3K/p-Akt pathway plays a critical role in mediating the salutary effects of estradiol on histopathological changes and neurological outcomes following TBI, suggesting that GPER and classic ERs are involved in regulating the expression of PI3K/p-Akt.

Antineoplastic drugs in environmentally relevant concentrations cause endocrine disruption and testicular dysfunction in experimental conditions

5-fluorouracil (5-FU) and methotrexate (MTX) are among the most widely consumed antineoplastic drugs worldwide. These drugs are known as emerging pollutants, once after consumption are excreted by feces and/or urine in a mixture of compounds and metabolites, entering the aquatic environment due to low efficiency in drug removal by effluent treatment plants. Considering that these substances may interact with the DNA, causing metabolic and morphological changes, leading to cell death, the present study aimed to investigate the potential impact of a long-term exposure to these antineoplastic drugs in environmentally relevant concentrations, on testicular morphophysiology of rats. Male Wistar rats (70 days old) were distributed into 4 groups (n = 10 / group): control, received only vehicle; MTX, received methotrexate at 10ngL-1 in drinking water; 5-FU received 5-fluorouracil at 10ngL-1 in drinking water; and MTX+ 5FU, received the combination of MTX and 5-FU at 10ngL-1 each. The treatment period was from postnatal day (PND)70 to PND160, when the animals were euthanized for evaluation of testicular toxicity and changes in endocrine signaling. In these experimental conditions, both drugs acted as endocrine disruptors causing cytotoxic effects in the testes of exposed rats, altering the structural pattern of seminiferous tubules and leading to oxidative stress even at environmental concentrations.

Therapeutic potential of testosterone on sperm parameters and chromatin status in fresh and thawed normo and asthenozoospermic samples

BACKGROUND

Hormonal changes alter the physiological level of ROS and cause oxidative stress in the cell. As estimated, hormonal deficiencies, environmental and ideological factors make up about 25% of male infertility. Pathogenic reactive oxygen species (ROS) is a chief cause of unexplained infertility. Limited studies exist on the effects of testosterone on human sperm culture. Therefore, in the current study, the effect of different doses of testosterone on sperm parameters and chromatin quality was investigated.

MATERIALS AND METHODS

Semen samples from 15 normospermic and 15 asthenospermic patients were prepared by swim up method, and then were divided into four groups by exposing to different concentrations of testosterone (1, 10, and 100nM) for 45min. Samples without any intervention were considered as control group. All samples were washed twice. Sperm parameters and chromatin protamination were assessed in each group and the remains were frozen. After two weeks, all tests were repeated for sperm thawed. Also, the MSOM technique was used to determine the sperm morphology of class 1.

RESULTS

Although sperm parameters were not show any significant differences in normospermic and asthenospermic samples exposed to different concentrations of testosterone before and after freezing, chromatin protamination was significantly decreased in the normospermic samples exposed to 10nM of testosterone before freezing (p<0.006), as well as 1 and 10nM of testosterone after freezing compared to control samples (p=0.001 and p=0.0009, respectively). Similarly, chromatin protamination in the asthenospermic samples was significantly decreased at concentration of 1nM of testosterone before and after freezing (p=0.0014 and p=0.0004, respectively), and at concentration of 10nM of testosterone before and after freezing (p=0.0009, p=0.0007) compared to control samples.

CONCLUSION

Using a low dose of testosterone in the sperm culture medium, has positive effects on chromatin quality.

An integrated study of hormone-related sarcopenia for modeling and comparative transcriptome in rats

Sarcopenia is a senile disease with high morbidity, serious complications and limited clinical treatments. Menopause increases the risk of sarcopenia in females, while the exact pathogenesis remains unclear. To systematically investigate the development of hormone-related sarcopenia, we established a model of sarcopenia by ovariectomy and recorded successive characteristic changes. Furthermore, we performed the transcriptome RNA sequencing and bioinformatics analysis on this model to explore the underlying mechanism. In our study, we identified an integrated model combining obesity, osteoporosis and sarcopenia. Functional enrichment analyses showed that most of the significantly enriched pathways were down-regulated and closely correlated with endocrine and metabolism, muscle dysfunction, cognitive impairment and multiple important signaling pathways. We finally selected eight candidate genes to verify their expression levels. These findings confirmed the importance of estrogen in the maintenance of skeletal muscle function and homeostasis, and provided potential targets for further study on hormone-related sarcopenia.

Ameliorative effect of avocado oil against lufenuron induced testicular damage and infertility in male rats

Lufenuron is a benzoylurea pesticide that causes significant histological and histochemical damage in mammals. Avocado is a common food in the human diet that contains antioxidant and antitumor properties. In male rats, avocado oil's protection against lufenuron-induced reproductive deterioration, oxidative stress, and DNA damages was investigated. Twenty-eight mature male rats were selected and distributed into four groups: Group 1, control group were administered distilled water orally; Group 2 received 4 ml/kg avocado; Group 3 was given lufenuron (1.6 mg/kg), and Group 4 was given avocado oil/lufenuron. The findings show that lufenuron treatment reduces reproductive hormone levels, sperm count, motility, viability and causes negative histopathological changes in testicular tissue, such as decreased epithelial height and increased luminal diameter degenerated spermatogenesis. Furthermore, lufenuron reduced the content of antioxidant enzymes while increasing the level of malondialdehyde, nitric oxide and corresponding DNA damage. Results showed that lufenuron is associated with testicular function impairment, which leads to infertility. Treatment with avocado oil improved reproductive hormone secretions, enzymatic activity, histological and DNA damage parameters in testis tissues, reducing the negative effects of lufenuron, proving that it may have a therapeutic role against lufenuron-mediated testicular toxicity.

Testosterone propionate improves motor alterations and dopaminergic damage in the reserpine-induced progressive model of Parkinson's disease

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder with a higher susceptibility to occur in men. Studies suggest that this susceptibility is related to the hormonal differences observed between men and women, being a risk factor for PD. In addition, testosterone supplementation has shown controversial results in animal models of PD and parkinsonian patients. This study evaluated the effect of chronic administration of testosterone propionate (TP) on motor behavior and neurochemical parameters in the reserpine-induced rat model of parkinsonism. Male Wistar rats received 15 injections of reserpine (RES - 0.1 mg/kg) every other day and were concomitantly treated with different doses (0.1, 1.0, or 5.0 mg/kg) of daily TP for 30 days. The rats were euthanized 48 h after the 15th injection of RES or vehicle. Brains were removed and subjected to Tyrosine hydroxylase (TH) immunohistochemistry. TP at 1.0 mg/kg reduced the damages caused by reserpine in the vacuous chewing and tong protrusion behaviors and prevented dopaminergic damage in the SNpc, VTA, and Striatum. TP at 5.0 mg/kg reduced the damages caused by reserpine in the catalepsy and tong protrusion behaviors, prevented the weight loss, and prevented dopaminergic damage in the VTA. Our results suggest that chronic administration of TP has a protective effect in a rat model of parkinsonism, improving motor alterations and dopamine depletion induced by RES.

Role of exercise in estrogen deficiency-induced sarcopenia

A decline in estrogen levels during menopause is associated with the loss of muscle mass and function, and it can accelerate sarcopenia. However, with the growing number of postmenopausal women due to the increase in life expectancy, the effects of estrogen on skeletal muscle are not completely understood. This article reviews the relationship between estrogen deficiency and skeletal muscle, its potential mechanisms, including those involving mitochondria, and the effects of exercise on estrogen deficiency-induced skeletal muscle impairment. In particular, mitochondrial dysfunction induced by estrogen deficiency accelerates sarcopenia via mitochondrial dynamics, mitophagy, and mitochondrial-mediated apoptosis. It is well known that exercise training is essential for health, including for the improvement of sarcopenia. This review highlights the importance of exercise training (aerobic and resistance exercise) as a therapeutic intervention against estrogen deficiency-induced sarcopenia.

Genetic, Molecular, and Cellular Determinants of Sex-Specific Cardiovascular Traits

Despite the well-known sex dimorphism in cardiovascular disease traits, the exact genetic, molecular, and cellular underpinnings of these differences are not well understood. A growing body of evidence currently points at the links between cardiovascular disease traits and the genome, epigenome, transcriptome, and metabolome. However, the sex-specific differences in these links remain largely unstudied due to challenges in bioinformatic methods, inadequate statistical power, analytic costs, and paucity of valid experimental models. This review article provides an overview of the literature on sex differences in genetic architecture, heritability, epigenetic changes, transcriptomic signatures, and metabolomic profiles in relation to cardiovascular disease traits. We also review the literature on the associations between sex hormones and cardiovascular disease traits and discuss the potential mechanisms underlying these associations, focusing on human studies.

The effect of testosterone and antioxidants nanoliposomes on gene expressions and sperm parameters in asthenospermic individuals

BACKGROUND

antioxidants that used for the infertility treatment cannot have their complete effectiveness, because of their instability in the culture medium.

SIGNIFICANCE

one of the most advances, in the drug delivery systems, is nanoliposomes-loaded, as biodegradable and bioavailable carriers. Hormonal and antioxidant agents encapsulating inside the nanoliposomes were used, to increase the effectiveness of antioxidants in the sperm culture medium.

MATERIALS

Semen sample from 15 asthenospermia were divided into 10 equal parts. After preparation, the sperms were incubated with free form of drugs and nanocarriers contained resveratrol, catalase, resveratrol-catalase and testosterone for 45 min. All sperm parameters, sperm DNA and gene expressions were evaluated before and after freezing.

RESULTS

Before freezing, all nanocarriers and free testosterone showed higher sperm motility compared to free drugs (P=.000). Free Testosterone and free resveratrol-catalase had higher DNA damage compared to nanocarriers (P=.000). Before freezing, the blank nanoliposome and testosterone nanoliposomes had the lowest HSP70 gene expression respectively (P = 0.005) (P = 0.001). After freezing, a significant reduction in sperm motility was observed in the free resveratrol-catalase group (P=.003). Also, a significant increase in sperm viability was observed in the free testosterone and nanoliposomes of blank and testosterone (P > 0.05). The least DNA damage was related to catalase nanoliposomes (P=.000). All nanoliposomes, especially catalase, had the highest percentage of class I morphology compared to the control group (P=.000).

CONCLUSIONS

Nanoliposomes could improve the sperm parameters and DNA integrity before and after freezing, by increasing the effectiveness of antioxidants. So, it can be recommended in the ART lab.

Oxidative Stress and Gender Disparity in Cancer

Oxidative stress is caused by homeostasis disrupted by excessively increased reactive oxygen species (ROS) due to intrinsic or extrinsic causes. Among diseases caused by the abnormal induction of ROS, cancer is a representative disease that shows gender specificity in the development and malignancy. Females have the advantage of longer life expectancy than males because of the genetic advantages derived from X chromosomes, the antioxidant protective function by estrogen, and the decrease in exposure to extrinsic risk factors such as alcohol and smoking. This study first examines the ordinary biological responses to oxidative stress and the effects of ROS on the cancer progression and describes the differences in cancer incidence and mortality by gender and the differences in oxidative stress affected by sex hormones. This paper summarized how several important transcription factors regulate ROS-induced stress and in vivo responses, and how their expression is changed by sex hormones. Estrogen is associated with disease resistance and greater mitochondrial function, and reduces mitochondrial damage and ROS production in females than in males. In addition, estrogen affects the activation of nuclear factor-erythroid 2 p45-related factor (NRF) 2 and the regulation of other antioxidant-related transcription factors through NRF2, leading to benefits in females. Because ROS have a variety of molecular targets in cells, the effective cancer treatment requires understanding the potential of ROS and focusing on the characteristics of the research target such as patient's gender. Therefore, this review intends to emphasize the necessity of discussing gender specificity as a new therapeutic approach for efficient regulation of ROS considering individual specificity.

Modification of the toxic effects of methylmercury and thimerosal by testosterone and estradiol in SH-SY5Y neuroblastoma cell line

Short-chained alkyl mercury compounds accumulate in particularly in the brain. Exposure to these compounds is associated with various neurotoxic effects. Gender-based differences are observed in neurodevelopmental disorders, and testosterone and estradiol may alter the toxic effect of the compounds. The present study aimed to investigate the toxic effects of methylmercury and thimerosal on SH-SY5Y cells in high testosterone/low estradiol and high estradiol/low testosterone containing cellular environment and estimate whether male and female brains react differently to the toxic effects of methylmercury and thimerosal. Study groups (n = 3) were designed as control: growth medium, thimerosal (T): 1.15-μM thimerosal, methylmercury (M): 2.93-μM methylmercury, high testosterone/low estradiol + thimerosal (TT): 1-μM testosterone + 0.75-μM estradiol + 1.15-μM thimerosal, high estradiol/low testosterone + thimerosal (ET): 0.1-μM testosterone + 7.5-μM estradiol + 1.15-μM thimerosal, high testosterone/low estradiol + methylmercury (TM): 1-μM testosterone + 0.75-μM estradiol + 2.93-μM methylmercury and high estradiol/low testosterone + methylmercury (EM): 0.1-μM testosterone + 7.5-μM estradiol + 2.93-μM methylmercury. While a significant decrease in glutathione levels was observed in M group, it was not seen in EM group. A significant increase in the protein carbonyl levels was detected in T group. A similar increase was observed in the TM and TT groups in which testosterone was dominant. It was determined that methylmercury, but not thimerosal, caused significant DNA damage and in TT group. The results showed that both thimerosal and methylmercury are toxic on SH-SY5Y cells and toxic effects of methylmercury are more severe than thimerosal. It has been determined that testosterone and estradiol alter the toxic effects of thimerosal and methylmercury.

Hyperandrogenemia alters mitochondrial structure and function in the oocytes of obese mouse with polycystic ovary syndrome

Capsule

Hyperandrogenemia in an obese PCOS mouse model results in altered glucose/insulin metabolism and mitochondrial structure and function in the oocytes, in part explaining adverse outcomes and inheritance patterns seen in PCOS.

Objective

To study the oocyte quality by means of mitochondrial structure and function in a well-established classic PCOS mouse model.

Design

Animal study using an obese PCOS mouse model compared with control.

Setting

Animal research facility in a tertiary care university hospital setting.

Animals

C57/B6J mice.

Intervention

Three week old mice had subdermal implants of DHT controlled release pellet or placebo for 90 days.

Main Outcome Measures

The mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were subsequently isolated and were used to investigate mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance, histology and electron microscopy.

Results

Results showed glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of the oocytes demonstrated impaired inner mitochondrial membrane function, increased ATP production and mtDNA copy number, altered RNA transcript abundance and aberrant ovarian histology. Electron microscopy of the oocytes showed severely impaired mitochondrial ultrastructure.

Conclusion

The obese PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial function.

Energy Metabolism Focused Analysis of Sexual Dimorphism in Biological Aging and Hypothesized Sex-specificity in Sirtuin Dependency

The process of biological aging or senescence refers to the gradual loss of homeostasis and subsequent loss of function - leading to higher chances of mortality. Many mechanisms and driving forces have been suggested to facilitate the evolution of a molecular circuit acting as a trade-off between survival and proliferation, resulting in senescence. A major observation on biological aging and longevity in humans and model organisms is the prevalence of significant sexual divergence in the onset, mechanisms and effects of aging associated processes. In the current account, we describe possible mechanisms by which aging, sex and reproduction are evolutionarily intertwined in order to maintain systemic energy homeostasis. We also interrogate existing literature on the sexual dimorphism of genetic, cellular, metabolic, endocrine and epigenetic processes driving cellular and systemic aging. Subsequently, based on available evidence, we propose a hypothetic model of sex-limited decoupling of female longevity from sirtuins, a major family of regulator proteins of the survival-proliferation trade-off. We also provide necessary considerations to be made in order to test the hypothesis and explore the physiological and therapeutic implications of this decoupling event in male and female longevity after reaching reproductive maturity. HYPOTHESIS STATEMENT: Sirtuins provide survival benefits in a sex-nonspecific manner but the dependency on sirtuins in driving metabolic networks after reaching reproductive maturity is evolutionarily decoupled from female longevity.

Androgen/Androgen Receptor Signaling in Ovarian Cancer: Molecular Regulation and Therapeutic Potentials

Ovarian cancer (OVCA) arises from three cellular origins, namely surface epithelial cells, germ cells, and stromal cells. More than 85% of OVCAs are EOCs (epithelial ovarian carcinomas), which are the most lethal gynecological malignancies. Cancer stem/progenitor cells (CSPCs) are considered to be cancer promoters due to their capacity for unlimited self-renewal and drug resistance. Androgen receptor (AR) belongs to the nuclear receptor superfamily and can be activated through binding to its ligand androgens. Studies have reported an association between AR expression and EOC carcinogenesis, and AR is suggested to be involved in proliferation, migration/invasion, and stemness. In addition, alternative AR activating signals, including both ligand-dependent and ligand-independent, are involved in OVCA progression. Although some clinical trials have previously been conducted to evaluate the effects of anti-androgens in EOC, no significant results have been reported. In contrast, experimental studies evaluating the effects of anti-androgen or anti-AR reagents in AR-expressing EOC models have demonstrated positive results for suppressing disease progression. Since AR is involved in complex signaling pathways and may be expressed at various levels in OVCA, the aim of this article was to provide an overview of current studies and perspectives regarding the relevance of androgen/AR roles in OVCA.

The Hepatoprotective mechanisms of 17β-estradiol after traumatic brain injury in male rats: Classical and non-classical estrogen receptors

Protective effects of estrogen (E2) on traumatic brain injury (TBI) have been determined. In this study, the hepatoprotective effects of E2 after TBI through its receptors and oxidative stress regulation have been evaluated. Diffuse TBI induced by the Marmarou method in male rats. G15, PHTPP, MPP, and ICI182-780 as selective antagonists of E2 were injected before TBI. The results indicated that TBI induces a significant increase in liver enzymes [Alkaline phosphatase (ALP), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Glutamyl transferase (GGT)], and oxidants levels [Malondialdehyde (MDA), Nitric oxide (NO)] and decreases in antioxidant biomarkers [Glutathione peroxidase (GPx) and Superoxide dismutase (SOD)] in the brain and liver, and plasma. We also found that E2 significantly preserved levels of these biomarkers and enzymatic activity. All antagonists inhibited the effects of E2 on increasing SOD and GPx. Also, the effects of E2 on brain MDA levels were inhibited by all antagonists, but in the liver, only ICI + G15 + E2 + TBI group was affected. The impacts of E2 on brain and liver and plasma NO levels were inhibited by all antagonists. The current findings demonstrated that E2 probably improved liver injury after TBI by modulating oxidative stress. Also, both classic (ERβ, ERα) and non-classic [G protein-coupled estrogen receptor (GPER)] receptors are affected in the protective effects of E2.

Direct and Indirect Effects of Sex Steroids on Gonadotrope Cell Plasticity in the Teleost Fish Pituitary

The pituitary gland controls many important physiological processes in vertebrates, including growth, homeostasis, and reproduction. As in mammals, the teleost pituitary exhibits a high degree of plasticity. This plasticity permits changes in hormone production and secretion necessary to meet the fluctuating demands over the life of an animal. Pituitary plasticity is achieved at both cellular and population levels. At the cellular level, hormone synthesis and release can be regulated via changes in cell composition to modulate both sensitivity and response to different signals. At the cell population level, the number of cells producing a given hormone can change due to proliferation, differentiation of progenitor cells, or transdifferentiation of specific cell types. Gonadotropes, which play an important role in the control of reproduction, have been intensively investigated during the last decades and found to display plasticity. To ensure appropriate endocrine function, gonadotropes rely on external and internal signals integrated at the brain level or by the gonadotropes themselves. One important group of internal signals is the sex steroids, produced mainly by the gonadal steroidogenic cells. Sex steroids have been shown to exert complex effects on the teleost pituitary, with differential effects depending on the species investigated, physiological status or sex of the animal, and dose or method of administration. This review summarizes current knowledge of the effects of sex steroids (androgens and estrogens) on gonadotrope cell plasticity in teleost anterior pituitary, discriminating direct from indirect effects.

Reproductive effects of subchronic exposure to acetamiprid in male rats

Acetamiprid, a selective agonist of nicotinic acetylcholine recetors, is one of the most widely used neonicotinoids. There is limited data about toxicity of acetamiprid on male reproductive system. Therefore, the study aimed to investigate the reproductive toxic potential of acetamiprid in male rats orally treated with acetamiprid with low (12.5 mg/kg) medium (25 mg/kg) or high dose (35 mg/kg) for 90 days. According to our results, sperm concentration and plasma testosterone levels decreased in dose dependent manner. Gonadotropin-releasing hormone (GnRH), follicle-stimulating hormeone (FSH), luteinizing hormone (LH) levels increased at low and medium dose groups and acetamiprid caused lipid peroxidation and glutathione (GSH) depletion in the testes. Histologic examinations revealed that acetamiprid induced apoptosis in medium and high dose groups and proliferation index dramatically decreased in high dose group. In conclusion, acetamiprid caused toxicity on male reproductive system in the high dose. The mechanism of the toxic effect may be associated with oxidative stress, hormonal disruptions and apoptosis.

Sex differences in the response to oxidative and proteolytic stress

Sex differences in diseases involving oxidative and proteolytic stress are common, including greater ischemic heart disease, Parkinson disease and stroke in men, and greater Alzheimer disease in women. Sex differences are also observed in stress response of cells and tissues, where female cells are generally more resistant to heat and oxidative stress-induced cell death. Studies implicate beneficial effects of estrogen, as well as cell-autonomous effects including superior mitochondrial function and increased expression of stress response genes in female cells relative to male cells. The p53 and forkhead box (FOX)-family genes, heat shock proteins (HSPs), and the apoptosis and autophagy pathways appear particularly important in mediating sex differences in stress response.

Prenatal androgen induced lean PCOS impairs mitochondria and mRNA profiles in oocytes

Polycystic ovary syndrome (PCOS) is the most common ovulatory defect in women. Although most PCOS patients are obese, a subset of PCOS women are lean but show similar risks for adverse fertility outcomes. A lean PCOS mouse model was created using prenatal androgen administration. This developmentally programmed mouse model was used for this study. Our objective was to investigate if mitochondrial structure and functions were compromised in oocytes obtained from lean PCOS mouse. The lean PCOS mouse model was validated by performing glucose tolerance test, HbA1c levels, body weight and estrous cycle analyses. Oocytes were isolated and were used to investigate inner mitochondrial membrane potential, oxidative stress, lipid peroxidation, ATP production, mtDNA copy number, transcript abundance, histology and electron microscopy. Our results demonstrate that lean PCOS mice has similar weight to that of the controls but exhibited glucose intolerance and hyperinsulinemia along with dysregulated estrus cycle. Analysis of their oocytes show impaired inner mitochondrial membrane function, elevated reactive oxygen species (ROS), increased RNA transcript abundance and aberrant ovarian histology. Electron microscopy of the oocytes showed impaired mitochondrial ultrastructure. In conclusion, the lean PCOS mouse model shows a decreased oocyte quality related to impaired mitochondrial ultrastructure and function.

Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)

Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E₂) in males of this species shows seasonal variations but, since testes of R. arenarum do not express aromatase, the source of plasma E₂ remained unknown for several years. However, the Bidder's organ (BO), a structure located at one pole of each testis, is proposed to be the main source of E₂ in male's toads since it expresses several steroidogenic enzymes and is able to produce E₂ from endogenous substrates throughout the year. In addition, there were significant correlations between plasma E₂ and total activity of BO aromatase, and between plasma E₂ and the amount of hormone produced by the BO in vitro. In the toad, apoptosis induced by in vitro treatment with E₂ was mostly detected in spermatocytes during the breeding and in spermatids during the post-reproductive season, suggesting that this steroid has an important role in controlling spermatogenesis. However, in vitro treatment with E₂ had no effect on proliferation. This evidence suggests that the mechanism of action of E₂ on amphibian spermatogenesis is complex and more studies are necessary to fully understand the role of estrogens regulating the balance between cellular proliferation and apoptosis. In addition, in R. arenarum in vitro studies suggested that E₂ has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) activity during the post reproductive season. As well, E₂ regulates FSHβ mRNA expression all over the year suggesting a down regulation process carried out by this steroid. The effect on LHβ mRNA is dual, since during the reproductive season estradiol increases the expression of LHβ mRNA while in the non-reproductive season it has no effect. In conclusion, the effect of E₂ on gonadotropins and testicular function is complex, not clearly understood and probably varies depending on the species. The aim of the current article is to review evidence on reproductive endocrinology and on the role of estradiol regulating reproduction in amphibians, with emphasis on the South American species Rhinella arenarum.

Estrogens, Estrogen Receptors Effects on Cardiac and Skeletal Muscle Mitochondria

Mitochondria are unique organelles present in almost all cell types. They are involved not only in the supply of energy to the host cell, but also in multiple biochemical and biological processes like calcium homeostasis, production, and regulation of reactive oxygen species (ROS), pH control, or cell death. The importance of mitochondria in cell biology and pathology is increasingly recognized. Being maternally inherited, mitochondria exhibit a tissue-specificity, because most of the mitochondrial proteins are encoded by the nuclear genome. This renders them exquisitely well-adapted to the physiology of the host cell. It is thus not surprising that mitochondria show a sexual dimorphism and that they are also prone to the influence of sex chromosomes and sex hormones. Estrogens affect mitochondria through multiple processes involving membrane and nuclear estrogen receptors (ERs) as well as more direct effects. Moreover, estrogen receptors have been identified within mitochondria. The effects of estrogens on mitochondria comprise protein content and specific activity of mitochondrial proteins, phospholipid content of membranes, oxidant and anti-oxidant capacities, oxidative phosphorylation, and calcium retention capacities. Herein we will briefly review the life cycle and functions of mitochondria, the importance of estrogen receptors and the effects of estrogens on heart and skeletal muscle mitochondria.

Influences of Sex and Estrogen in Arterial and Valvular Calcification

Vascular and cardiac valvular calcification was once considered to be a degenerative and end stage product in aging cardiovascular tissues. Over the past two decades, however, a critical mass of data has shown that cardiovascular calcification can be an active and highly regulated process. While the incidence of calcification in the coronary arteries and cardiac valves is higher in men than in age-matched women, a high index of calcification associates with increased morbidity, and mortality in both sexes. Despite the ubiquitous portending of poor outcomes in both sexes, our understanding of mechanisms of calcification under the dramatically different biological contexts of sex and hormonal milieu remains rudimentary. Understanding how the critical context of these variables inform our understanding of mechanisms of calcification-as well as innovative strategies to target it therapeutically-is essential to advancing the fields of both cardiovascular disease and fundamental mechanisms of aging. This review will explore potential sex and sex-steroid differences in the basic biological pathways associated with vascular and cardiac valvular tissue calcification, and potential strategies of pharmacological therapy to reduce or slow these processes.

Estrogen Regulation of T-Cell Function and Its Impact on the Tumor Microenvironment

Epidemiologic studies demonstrate significant gender-specific differences in immune system function. Males are more prone to infection and malignancies, while females are more vulnerable to autoimmune diseases. These differences are thought to be due to the action of gonadal hormones: Estrogen increases the inflammatory response and testosterone dampens it. More specifically, estrogen stimulation induces inflammatory cytokine production including interferon γ, interleukin (IL) 6, and tumor necrosis factor α, while testosterone induces IL-10, IL-4, and transforming growth factor β. More recent studies demonstrate threshold effects of estrogen stimulation on immune cell function: physiologic doses of estrogen (approximately 0.5 nmol/L) stimulate inflammatory cytokine production, but superphysiologic dosages (above 50 nmol/L) can result in decreased inflammatory cytokine production. This review reports findings concerning the impact of estrogen on CD8+ cytotoxic T cells and the overall immune response in the tumor microenvironment. Variables examined include dosage of hormone, the diversity of immune cells involved, and the nature of the immune response in cancer. Collective review of these points may assist in future hypotheses and studies to determine sex-specific differences in immune responses that may be used as targets in disease prevention and treatment.

Estradiol Attenuates the Severity of Primary Toxoplasma gondii Infection-Induced Adverse Pregnancy Outcomes Through the Regulation of Tregs in a Dose-Dependent Manner

Estradiol (E2) plays a crucial and intricate role during pregnancy to mediate several aspects of the pregnancy process. A perplexing phenomenon in congenital toxoplasmosis is that the severity of Toxoplasma gondii (T. gondii)-mediated adverse pregnancy outcome is closely related with time of primary maternal infection during pregnancy. In this study, the results showed that T. gondii infection in early pregnancy was more likely to induce miscarriage in mice than in late pregnancy, which may be related to inflammation of the maternal–fetal interface. Meanwhile, the T. gondii infection-induced-apoptotic rate of Tregs was higher and the expression of programmed death-1 (PD-1) on Tregs was lower in early pregnancy than in late pregnancy. As the level of E2 in mouse serum gradually increased with the development of pregnancy, we proposed that E2 may contribute to the discrepancy of Tregs at different stages of pregnancy. Thus, we investigated in vitro and in vivo effects of E2 in regulating Tregs. We found that E2 in vitro could protect Tregs against apoptosis and upregulate the expression of PD-1 on Tregs in a dose-dependent manner through ERα. Likewise, the simulated mid-pregnancy level of E2 in nonpregnant mice also alleviated the T. gondii infection-induced apoptosis of Tregs and potentiated the PD-1 expression on Tregs. Therefore, in the pathogenesis of T. gondii-induced abnormal pregnancy, E2 helped maintain the immune balance and improve the pregnancy outcome through regulating Tregs. This finding illustrates the intricate working of hormone–immune system interaction in infection-induced abnormal pregnancy.

Developmental effects of androgens in the human brain

Neuroendocrine theories of brain development posit that androgens play a crucial role in sex-specific cortical growth, although little is known about the differential effects of testosterone and dehydroepiandrosterone (DHEA) on cortico-limbic development and cognition during adolescence. In this context, the National Institutes of Health Study of Normal Brain Development, a longitudinal study of typically developing children and adolescents aged 4-24 years (n=433), offers a unique opportunity to examine the developmental effects of androgens on cortico-limbic maturation and cognition. Using data from this sample, our group found that higher testosterone levels were associated with left-sided decreases in cortical thickness (CTh) in post-pubertal boys, particularly in the prefrontal cortex, compared to right-sided increases in CTh in somatosensory areas in pre-pubertal girls. Prefrontal-amygdala and prefrontal-hippocampal structural covariance (considered to reflect structural connectivity) also varied according to testosterone levels, with the testosterone-related brain phenotype predicting higher aggression levels and lower executive function, particularly in boys. By contrast, DHEA was associated with a pre-pubertal increase in CTh of several regions involved in cognitive control in both boys and girls. Covariance within several cortico-amygdalar structural networks also varied as a function of DHEA levels, with the DHEA-related brain phenotype predicting improvements in visual attention in both boys and girls. DHEA-related cortico-hippocampal structural covariance, on the other hand, predicted higher scores on a test of working memory. Interestingly, there were significant interactions between testosterone and DHEA, such that DHEA tended to mitigate the anti-proliferative effects of testosterone on brain structure. In sum, testosterone-related effects on the developing brain may lead to detrimental effects on cortical functions (ie, higher aggression and lower executive function), whereas DHEA-related effects may optimise cortical functions (ie, better attention and working memory), perhaps by decreasing the influence of amygdalar and hippocampal afferents on cortical functions.

Brain structural connectivity during adrenarche: Associations between hormone levels and white matter microstructure

Levels of the adrenal hormones dehydroepiandrosterone (DHEA), its sulfate (DHEAS), and testosterone, have all been linked to behavior and mental health during adrenarche, and preclinical studies suggest that these hormones influence brain development. However, little is known about how variation in these hormones is associated with white matter structure during this period of life. The current study aimed to examine associations between DHEA, DHEAS, and testosterone, and white matter microstructure during adrenarche. To avoid the confounding effect of age on hormone levels, we tested these associations in 87 children within a narrow age range (mean age 9.56 years, SD=0.34) but varying in hormone levels. All children provided saliva samples directly after waking and completed a diffusion-weighted MRI scan. Higher levels of DHEA were associated with higher mean diffusivity (MD) in a widespread cluster of white matter tracts, which was partially explained by higher radial diffusivity (RD) and partially by higher axial diffusivity (AD). In addition, there was an interaction between DHEA and testosterone, with higher levels of testosterone being associated with higher fractional anisotropy (FA) and lower MD and RD when DHEA levels were relatively high, but with lower FA and higher MD and RD when DHEA levels were low. These findings suggest that relatively early exposure to DHEA, as well as an imbalance between the adrenal hormones, may be associated with alterations in white matter microstructure. These findings highlight the potential relevance of adrenarcheal hormones for structural brain development.

Sexual Dimorphism and Aging Differentially Regulate Adaptive Homeostasis

External and internal stimuli cause modifications to gene and biochemical pathways. In turn, demonstrating that biological systems continuously make short-term adaptations both to set-points, and to the range of "normal" capacity, due to mild conditional changes, or to subtoxic, nondamaging levels of chemical agents. This is termed as "Adaptive Homeostasis," defined with the following: "The transient expansion or contraction of the homeostatic range in response to exposure to sub-toxic, nondamaging, signaling molecules or events, or the removal or cessation of such molecules or events." Research from several laboratories, including our own, found that adaptive homeostasis declines with age in organisms as diverse as worms, flies, and mammals, and decreases with senescence in mammalian cell cultures. We suggest that diminishing adaptive homeostasis may play a causal role as a factor responsible for the aging phenotype. Furthermore, although studies of humans, animals, and model organisms are often limited to a single sex, and cell culture studies may even be conducted with lines whose donor's sex was unknown, studies reveal distinct sexual dimorphism in adaptive homeostasis. Interestingly, although young males and females may exhibit dramatic differences in adaptive capacities and/or preferences, these distinctions are lost with age as adaptive homeostasis patterns converge.

Estrogenic terpenes and terpenoids: Pathways, functions and applications

Terpenes are made of the isoprene unit (C₅), and along with their derivatives, terpenoids, they are widely distributed in plants as active ingredients involved in anti-inflammation, anti-carcinogenesis and neuroprotection. Estrogenic terpenes and terpenoids are an important category of phytoestrogens and have been used as traditional medicines. The comprehensive list of estrogenic terpenes and terpenoids includes hemi-, mono-, sesqui-, di-, tri-, tetra- and polyterpenes, their derivatives, and meroterpenes, along with the signaling pathways and cellular functions on which their estrogenicity is exerted. Signaling pathways are further classified as bidirectional or unidirectional, the latter being further divided into two types depending upon the presence of both ligands, or the absence of one or both ligands. Although estrogenic activity of terpenes and terpenoids was evaluated by ligand-binding assays, yeast two-hybrid assays, reporter-gene assays, transcription assays, protein assays, cell assays and animal testing, the mechanism of estrogenic activity is still not fully understood. Applications of estrogenic terpenes and terpenoids are categorized into cancer treatment and prevention, cardioprotection, endocrine toxicity/reproductive dysfunction, food/supplement/traditional medicine, immunology/inflammation, menopausal syndromes and neuroprotection, where their benefits are discussed based on their availability, stability and variations.

Effect of neonatal hypothyroidism on prepubertal mouse testis in relation to thyroid hormone receptor alpha 1 (THRα1)

Thyroid hormones (THs) are important for growth and development of many tissues, and altered thyroid status affects various organs and systems. Testis also is considered as a thyroid hormone responsive organ. Though THs play an important role in regulation of testicular steroidogenesis and spermatogenesis, the exact mechanism of this regulation remains poorly understood. The present study, therefore, is designed to examine the effect of neonatal hypothyroidism on prepubertal Parkes (P) strain mice testis in relation to thyroid hormone receptor alpha 1 (THRα1). Hypothyroidism was induced by administration of 6-propyl-2-thiouracil (PTU) in mother's drinking water from birth to day 28; on postnatal day (PND) 21 only pups, and on PND 28, both pups and lactating dams were euthanized. Serum T₃ and T₄ were markedly reduced in pups at PND 28 and in lactating mothers, while serum and intra-testicular testosterone levels were considerably decreased in pups of both age groups. Further, serum and intra-testicular levels of estrogen were significantly increased in hypothyroid mice at PND 28 with concomitant increase in CYP19 expression. Histologically, marked changes were noticed in testes of PTU-treated mice; immunohistochemical and western blot analyses of testes in treated mice also revealed marked decrease in the expression of THRα1 at both age groups. Semiquantitative RT-PCR and western blot analyses also showed reductions in both testicular mRNA and protein levels of SF-1, StAR, CYP11A1 and 3β-HSD in these mice. In conclusion, our results suggest that neonatal hypothyroidism alters localization and expression of THRα1 and impairs testicular steroidogenesis by down-regulating the expression SF-1, thereby affecting spermatogenesis in prepubertal mice.

Pathophysiology of Aortic Valve Stenosis: Is It Both Fibrocalcific and Sex Specific?

Our understanding of the fundamental biology and identification of efficacious therapeutic targets in aortic valve stenosis has lagged far behind the fields of atherosclerosis and heart failure. In this review, we highlight the most clinically relevant problems facing men and women with fibrocalcific aortic valve stenosis, discuss the fundamental biology underlying valve calcification and fibrosis, and identify key molecular points of intersection with sex hormone signaling.

Sex Differences in Muscle Wasting

With aging and other muscle wasting diseases, men and women undergo similar pathological changes in skeletal muscle: increased inflammation, enhanced oxidative stress, mitochondrial dysfunction, satellite cell senescence, elevated apoptosis and proteasome activity, and suppressed protein synthesis and myocyte regeneration. Decreased food intake and physical activity also indirectly contribute to muscle wasting. Sex hormones also play important roles in maintaining skeletal muscle homeostasis. Testosterone is a potent anabolic factor promoting muscle protein synthesis and muscular regeneration. Estrogens have a protective effect on skeletal muscle by attenuating inflammation; however, the mechanisms of estrogen action in skeletal muscle are less well characterized than those of testosterone. Age- and/or disease-induced alterations in sex hormones are major contributors to muscle wasting. Hence, men and women may respond differently to catabolic conditions because of their hormonal profiles. Here we review the similarities and differences between men and women with common wasting conditions including sarcopenia and cachexia due to cancer, end-stage renal disease/chronic kidney disease, liver disease, chronic heart failure, and chronic obstructive pulmonary disease based on the literature in clinical studies. In addition, the responses in men and women to the commonly used therapeutic agents and their efficacy to improve muscle mass and function are also reviewed.

Extent of Vascular Remodeling Is Dependent on the Balance Between Estrogen Receptor α and G-Protein–Coupled Estrogen Receptor

Estrogens are important regulators of cardiovascular function. Some of estrogen’s cardiovascular effects are mediated by a G-protein–coupled receptor mechanism, namely, G-protein–coupled estrogen receptor (GPER). Estradiol-mediated regulation of vascular cell programmed cell death reflects the balance of the opposing actions of GPER versus estrogen receptor α (ERα). However, the significance of these opposing actions on the regulation of vascular smooth muscle cell proliferation or migration in vitro is unclear, and the significance in vivo is unknown. To determine the effects of GPER activation in vitro, we studied rat aortic vascular smooth muscle cells maintained in primary culture. GPER was reintroduced using adenoviral gene transfer. Both estradiol and G1, a GPER agonist, inhibited both proliferation and cell migration effects that were blocked by the GPER antagonist, G15. To determine the importance of the GPER-ERα balance in regulating vascular remodeling in a rat model of carotid ligation, we studied the effects of upregulation of GPER expression versus downregulation of ERα. Reintroduction of GPER significantly attenuated the extent of medial hypertrophy and attenuated the extent of CD45 labeling. Downregulation of ERα expression comparably attenuated the extent of medial hypertrophy and inflammation after carotid ligation. These studies demonstrate that the balance between GPER and ERα regulates vascular remodeling. Receptor-specific modulation of estrogen’s effects may be an important new approach in modifying vascular remodeling in both acute settings like vascular injury and perhaps in longer term regulation like in hypertension.

Testosterone Protects Mitochondrial Function and Regulates Neuroglobin Expression in Astrocytic Cells Exposed to Glucose Deprivation

Testosterone is a hormone that has been shown to confer neuroprotection from different insults affecting the central nervous system (CNS). Testosterone induces this protection by different mechanisms that include the activation of anti-apoptotic pathways that are directly implicated in neuronal survival. However, little attention has been devoted to its actions on glial cells. In the present study, we have assessed whether testosterone exerts protection in a human astrocyte cell model, the T98G cells. Our results indicate that testosterone improves cell survival and mitochondrial membrane potential and reduces nuclear fragmentation and reactive oxygen species (ROS) generation. These effects were accompanied by a positive regulation of neuroglobin, an oxygen-binding and sensor protein, which may serve as a regulator of ROS and nitrogen reactive species (NOS), and these protective effects of testosterone may be at least in part mediated by estradiol and DHT. In conclusion, these findings suggest that astroglia may mediate some of the protective actions of testosterone in the brain upon pathological conditions.

Sex Differences in Renal Proximal Tubular Cell Homeostasis

Studies in human patients and animals have revealed sex-specific differences in susceptibility to renal diseases. Because actions of female sex hormones on normal renal tissue might protect against damage, we searched for potential influences of the female hormone cycle on basic renal functions by studying excretion of urinary marker proteins in healthy human probands. We collected second morning spot urine samples of unmedicated naturally ovulating women, postmenopausal women, and men daily and determined urinary excretion of the renal tubular enzymes fructose-1,6-bisphosphatase and glutathione-S-transferase-α Additionally, we quantified urinary excretion of blood plasma proteins α1-microglobulin, albumin, and IgG. Naturally cycling women showed prominent peaks in the temporal pattern of urinary fructose-1,6-bisphosphatase and glutathione-S-transferase-α release exclusively within 7 days after ovulation or onset of menses. In contrast, postmenopausal women and men showed consistently low levels of urinary fructose-1,6-bisphosphatase excretion over comparable periods. We did not detect changes in urinary α1-microglobulin, albumin, or IgG excretion. Results of this study indicate that proximal tubular tissue architecture, representing a nonreproductive organ-derived epithelium, undergoes periodical adaptations phased by the female reproductive hormone cycle. The temporally delimited higher rate of enzymuria in ovulating women might be a sign of recurring increases of tubular cell turnover that potentially provide enhanced repair capacity and thus, higher resistance to renal damage.

Estrogen-mediated regulation of mitochondrial gene expression

Estrogens, in particular 17β-estradiol, are well-known regulators of essential cellular functions; however, discrepancies remain over the mechanisms by which they act on mitochondria. Here we propose a novel mechanism for the direct regulation of mitochondrial gene expression by estrogen under metabolic stress. We show that in serum-depleted medium, estrogen stimulates a rapid relocation of estrogen receptor-α to mitochondria, in which it elicits a cellular response, resulting in an increase in mitochondrial RNA abundance. Mitochondrial RNA levels are regulated through the association of estrogen receptor-α with 17β-hydroxysteroid dehydrogenase 10, a multifunctional protein involved in steroid metabolism that is also a core subunit of the mitochondrial ribonuclease P complex responsible for the cleavage of mitochondrial polycistronic transcripts. Processing of mitochondrial transcripts affects mitochondrial gene expression by controlling the levels of mature RNAs available for translation. This work provides the first mechanism linking RNA processing and estrogen activation in mitochondrial gene expression and underscores the coordinated response between the nucleus and mitochondria in response to stress.

17β-Estradiol and testosterone in sarcopenia: Role of satellite cells

The loss of muscle mass and strength with aging, referred to as sarcopenia, is a prevalent condition among the elderly. Although the molecular mechanisms underlying sarcopenia are unclear, evidence suggests that an age-related acceleration of myocyte loss via apoptosis might be responsible for muscle perfomance decline. Interestingly, sarcopenia has been associated to a deficit of sex hormones which decrease upon aging. The skeletal muscle ability to repair and regenerate itself would not be possible without satellite cells, a subpopulation of cells that remain quiescent throughout life. They are activated in response to stress, enabling them to guide skeletal muscle regeneration. Thus, these cells could be a key factor to overcome sarcopenia. Of importance, satellite cells are 17β-estradiol (E2) and testosterone (T) targets. In this review, we summarize potential mechanisms through which these hormones regulate satellite cells activation during skeletal muscle regeneration in the elderly. The advance in its understanding will help to the development of potential therapeutic agents to alleviate and treat sarcopenia and other related myophaties.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

Programmed cell death in aging

Programmed cell death (PCD) pathways, including apoptosis and regulated necrosis, are required for normal cell turnover and tissue homeostasis. Mis-regulation of PCD is increasingly implicated in aging and aging-related disease. During aging the cell turnover rate declines for several highly-mitotic tissues. Aging-associated disruptions in systemic and inter-cell signaling combined with cell-autonomous damage and mitochondrial malfunction result in increased PCD in some cell types, and decreased PCD in other cell types. Increased PCD during aging is implicated in immune system decline, skeletal muscle wasting (sarcopenia), loss of cells in the heart, and neurodegenerative disease. In contrast, cancer cells and senescent cells are resistant to PCD, enabling them to increase in abundance during aging. PCD pathways limit life span in fungi, but whether PCD pathways normally limit adult metazoan life span is not yet clear. PCD is regulated by a balance of negative and positive factors, including the mitochondria, which are particularly subject to aging-associated malfunction.

Estrogen receptors in the central nervous system and their implication for dopamine-dependent cognition in females

This article is part of a Special Issue "Estradiol and cognition". Over the past 30 years, research has demonstrated that estrogens not only are important for female reproduction, but also play a role in a diverse array of cognitive functions. Originally, estrogens were thought to have only one receptor, localized exclusively to the cytoplasm and nucleus of cells. However, it is now known that there are at least three estrogen receptors (ERs): ERα, ERβ and G-protein coupled ER1 (GPER1). In addition to being localized to nuclei, ERα and ERβ are localized to the cell membrane, and GPER1 is also observed at the cell membrane. The mechanism through which ERs are associated with the membrane remains unclear, but palmitoylation of receptors and associations between ERs and caveolin are implicated in membrane association. ERα and ERβ are mostly observed in the nucleus using light microscopy unless they are particularly abundant. However, electron microscopy has revealed that ERs are also found at the membrane in complimentary distributions in multiple brain regions, many of which are innervated by dopamine inputs and were previously thought to contain few ERs. In particular, membrane-associated ERs are observed in the prefrontal cortex, dorsal striatum, nucleus accumbens, and hippocampus, all of which are involved in learning and memory. These findings provide a mechanism for the rapid effects of estrogens in these regions. The effects of estrogens on dopamine-dependent cognition likely result from binding at both nuclear and membrane-associated ERs, so elucidating the localization of membrane-associated ERs helps provide a more complete understanding of the cognitive effects of these hormones.