Hepatic Estrogen Receptor Research Articles

Hepatic estrogen receptor alpha drives masculinization in post-menopausal women with metabolic dysfunction-associated steatotic liver disease

Background & AimsThe loss of ovarian functions defining menopause leads to profound metabolic changes and heightens the risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD). Although estrogens primarily act on the female liver through the estrogen receptor alpha (ERα), the specific contribution of impaired ERα signaling in triggering MASLD after menopause remains unclear. MethodsTo fulfill this gap of knowledge, we compared the liver transcriptomes of sham-operated (SHAM) and ovariectomized (OVX) control and liver ERα knockout (LERKO) female mice by performing RNA-Seq analysis. ResultsOVX led to 1426 differentially expressed genes (DEGs) in the liver of control mice compared to 245 DEGs in LERKO mice. Gene ontology analysis revealed a distinct OVX-induced modulation of the liver transcriptome in LERKO compared to controls, indicating that hepatic ERα is functional and necessary for the complete reprogramming of liver metabolism in response to estrogen depletion. Additionally, we observed an OVX-dependent induction of male-biased genes, especially in the liver of control females, pointing to hepatic ERα involvement in the masculinization of the liver after estrogen loss. To investigate the translational relevance of such findings, we enquired liver samples from a cohort of 60 severely obese individuals (51 women; 9 men). Notably, a shift of the liver transcriptome toward a male-like profile was also observed only in obese women with MASLD (n = 43), especially in ≥51 years old women (15/15), suggesting that masculinization of female liver contributes to MASLD development in obese women. ConclusionsThese results highlight the role of hepatic ERα in driving masculinization of the liver transcriptome following menopause, pointing to this receptor as a potential pharmacological target for preventing MASLD in post-menopausal women. Impact and implicationsDespite the increased risk of developing MASLD after menopause, the specific contribution of impaired hepatic estrogen signaling in driving MASLD in females has been very few investigated, preventing, so far, the development of tailored strategies that address the specific mechanisms underlying MASLD in post-menopausal women.This study reveals the functional role of hepatic estrogen receptor alpha (ERα) in mediating liver metabolic changes in response to estrogens loss, leading to a shift in the liver transcriptome towards a male-like profile. In obese women, this shift is associated with the development of MASLD.These findings underscore the potential of targeting hepatic ERα as a promising approach for developing effective, sex-specific treatments to preserve liver health and prevent or limit the development and progression of MASLD in post-menopausal women.

FRI-543 Relevance of hepatic estrogen receptor alpha in liver metabolic adaptation during pregnancy

FRI-543 Relevance of hepatic estrogen receptor alpha in liver metabolic adaptation during pregnancy

Fluctuating and Stable High Temperatures Differentially Affect Reproductive Endocrinology of Female Pupfish.

For many fishes, reproductive function is thermally constrained such that exposure to temperatures above some upper threshold has detrimental effects on gametic development and maturation, spawning frequency, and mating behavior. Such impairment of reproductive performance at elevated temperatures involves changes to hypothalamic-pituitary-gonadal (HPG) axis signaling and diminished gonadal steroidogenesis. However, how HPG pathways respond to consistently high versus temporally elevated temperatures is not clear. Here, sexually mature Amargosa River Pupfish (Cyprinodon nevadensis amargosae) were maintained under thermal regimes of either stable ∼25°C (low temperature), diurnal cycling temperatures between ∼27 and 35°C (fluctuating temperature), or stable ∼35°C (high temperature) conditions for 50 days to examine effects of these conditions on HPG endocrine signaling components in the pituitary gland and gonad, ovarian and testicular gametogenesis status, and liver gene expression relating to oogenesis. Female pupfish maintained under stable high and fluctuating temperature treatments showed reduced gonadosomatic index values as well as a lower proportion of oocytes in the lipid droplet and vitellogenic stages. Females in both fluctuating and stable 35°C conditions exhibited reduced ovarian mRNAs for steroid acute regulatory protein (star), cholesterol side chain-cleavage enzyme, P450scc (cyp11a1), and 3β-hydroxysteroid dehydrogenase (3bhsd), while ovarian transcripts encoding 11β-hydroxysteroid dehydrogenase (11bhsd) and sex hormone-binding globulin (shbg) were elevated in females at constant 35°C only. Ovarian aromatase (cyp19a1a) mRNA levels were unaffected, but circulating 17β-estradiol (E2) was lower in females at 35°C compared to the fluctuating temperature condition. In the liver, mRNA levels for choriogenins and vitellogenin were downregulated in both the fluctuating and 35°C conditions, while hepatic estrogen receptor 2a (esr2a) and shbg mRNAs were elevated in 35°C females. Taken together, these results demonstrate the potential for elevated temperatures to impair ovarian steroidogenesis and reduce egg envelope and vitellogenin protein production in female C. n. amargosae pupfish, while also shedding light on how thermal regimes that only intermittently reach the upper thermal range for reproduction have differential impacts on reproductive endocrine pathways than constantly warm conditions.

Estrogens as immunotoxicants: 17α-ethinylestradiol exposure retards thymus development in zebrafish (Danio rerio).

Estrogenic endocrine disrupting compounds (EEDCs) can cause alterations in sexual development and reproductive function of fish. Growing evidence suggests that EEDCs can also interfere with development and function of innate immunity of fish. The present study examined a potential disruptive effect of EEDCs at field-relevant concentrations on the development of adaptive immunity, more specifically the thymus. Zebrafish (Danio rerio) were exposed from fertilization until 64 days post-fertilization (dpf) to environmentally relevant (3 and 10ng/L) concentrations of the synthetic estrogen 17α-ethinylestradiol (EE2). The exposure duration covered the period of initial thymus differentiation to maximum growth. Thymus development was assessed by histological and morphometric (thymus area) analysis, thymocyte number, and transcript levels of thymocyte marker genes. Additionally, transcript levels of the estrogen receptors (esr1 and esr2a) were determined. The EE2 exposure altered sexual development (gonad differentiation, transcript levels of hepatic vitellogenin and estrogen receptors) of zebrafish, as expected. At the same time, the EE2 treatment reduced the thymus growth (thymus area, thymocyte number) and transcript levels of thymus marker genes. The expression of the thymic estrogen receptors responded to the EE2 exposure but in a different pattern than the hepatic estrogen receptors. After the 64-day-exposure period, the juvenile fish were transferred into clean water for another 95 days to assess the reversibility of EE2-induced effects. The thymic alterations were found to be reversible in female zebrafish but persisted in males. The present study provides the first evidence that the development of the fish adaptive immune system is sensitive to EEDCs, and that this takes place at concentrations similar to those that disrupt sexual development.

An In Silico and In Vitro Study for Investigating Estrogenic Endocrine Effects of Emerging Persistent Pollutants Using Primary Hepatocytes from Grey Mullet (Mugil cephalus)

There is growing concern about the environmentally relevant concentrations of new emerging persistent organic pollutants, such as perfluorinated compounds and pharmaceuticals, which are found to bioaccumulate in aquatic organisms at concentrations suspected to cause reproductive toxicity due to the activation of estrogen receptor (ER) α and β subtypes. Here, we use a combined in silico and in vitro approach to evaluate the impact of perfluorononanoic acid (PFNA) and Enalapril (ENA) on grey mullet (Mugil cephalus) hepatic estrogen signaling pathway. ENA had weak agonist activity on ERα while PFNA showed moderate to high agonist binding to both ERs. According to these effects, hepatocytes incubation for 48 h to PFNA resulted in a concentration-dependent upregulation of ER and vitellogenin gene expression profiles, whereas only a small increase was observed in ERα mRNA levels for the highest ENA concentration. These data suggest a structure–activity relationship between hepatic ERs and these emerging pollutants.

Sex Difference in the Tolerance of Hepatic Ischemia-reperfusion Injury and Hepatic Estrogen Receptor Expression According to Age and Macrosteatosis in Healthy Living Liver Donors.

Hepatic estrogen signaling, which is important in liver injury/recovery, is determined by the level of systemic estrogen and hepatic estrogen receptor. We aimed to evaluate whether females' advantage in the tolerance of hepatic ischemia-reperfusion injury decreases according to the age of 40 y (systemic estrogen decrease) and macrosteatosis (hepatic estrogen receptor decrease). We included 358 living liver donors (128 female and 230 male individuals). The tolerance of hepatic ischemia-reperfusion injury was determined by the slope of the linear regression line modeling the relationship between the duration of intraoperative hepatic ischemia and the peak postoperative transaminase level. Estrogen receptor content was measured in the biopsied liver samples using immunohistochemistry. In the whole cohort, the regression slope for aspartate transaminase was comparable between female and male individuals (P = 0.940). Within the subgroup of donors aged ≤40 y, the regression slope was significantly smaller in female individuals (P = 0.031), whereas it was comparable within donors aged >40 y (P = 0.867). Within the subgroup of nonmacrosteatotic donors aged ≤40 y, the regression slope was significantly smaller in female individuals in univariable (P = 0.002) and multivariable analysis (P = 0.006), whereas the sex difference was not found within macrosteatotic donors aged ≤40 y (P = 0.685). Estrogen receptor content was significantly greater in female individuals within nonmacrosteatotic donors aged ≤40 y (P = 0.021), whereas it was not different in others of age >40 y or with macrosteatosis (P = 0.450). The tolerance of hepatic ischemia-reperfusion injury was greater in female individuals than in male individuals only when they were <40 y and without macrosteatosis. The results were in agreement with the hepatic estrogen receptor immunohistochemistry study.

Estetrol prevents Western diet–induced obesity and atheroma independently of hepatic estrogen receptor α

Estetrol (E4), a natural estrogen synthesized by the human fetal liver, is currently evaluated in phase III clinical studies as a new menopause hormone therapy. Indeed, E4 significantly improves vasomotor and genito-urinary menopausal symptoms and prevents bone demineralization. Compared with other estrogens, E4 was found to have limited effects on coagulation factors in the liver of women allowing to expect less thrombotic events. To fully delineate its clinical potential, the aim of this study was to assess the effect of E4 on metabolic disorders. Here, we studied the pathophysiological consequences of a Western diet (42% kcal fat, 0.2% cholesterol) in ovariectomized female mice under chronic E4 treatment. We showed that E4 reduces body weight gain and improves glucose tolerance in both C57Bl/6 and LDLR-/- mice. To evaluate the role of hepatic estrogen receptor (ER) α in the preventive effect of E4 against obesity and associated disorders such as atherosclerosis and steatosis, mice harboring a hepatocyte-specific ERα deletion (LERKO) were crossed with LDLR-/- mice. Our results demonstrated that, whereas liver ERα is dispensable for the E4 beneficial actions on obesity and atheroma, it is necessary to prevent steatosis in mice. Overall, these findings suggest that E4 could prevent metabolic, hepatic, and vascular disorders occurring at menopause, extending the potential medical interest of this natural estrogen as a new hormonal treatment.NEW & NOTEWORTHY Estetrol prevents obesity, steatosis, and atherosclerosis in mice fed a Western diet. Hepatic ERα is necessary for the prevention of steatosis, but not of obesity and atherosclerosis.

Predictors of Survival after Yttrium-90 Radioembolization of Chemotherapy-Refractory Hepatic Metastases from Breast Cancer

PurposeTo determine predictors of survival after transarterial radioembolization of hepatic metastases from breast cancer. Materials and MethodsTwenty-four patients with chemotherapy-refractory hepatic metastases from breast cancer who underwent radioembolization from 2013 to 2018 were evaluated based on various demographic and clinical factors before and after treatment. Overall survival (OS) was estimated by Kaplan–Meier method. Log-rank analysis was performed to determine predictors of prolonged OS from the time of first radioembolization and first hepatic metastasis diagnosis. ResultsMedian OS times were 35.4 and 48.6 months from first radioembolization and time of hepatic metastasis diagnosis, respectively. Radioembolization within 6 months of hepatic metastasis diagnosis was a positive predictor of survival from first radioembolization, with median OS of 38.9 months vs 22.1 months for others (P = .033). Estrogen receptor (ER)–positive status predicted prolonged survival (38.6 months for ER+ vs 5.4 months for ER−; P = .005). The presence of abdominal pain predicted poor median OS: 12.8 months vs 38.6 months for others (P < .001). The presence of ascites was also a negative predictor of OS (1.7 months vs 35.4 months for others; P = .037), as was treatment-related grade ≥ 2 toxicity at 3 months (5.4 months vs 38.6 months for others; P = .017). ConclusionsIn patients with metastatic breast cancer, radioembolization within 6 months of hepatic metastasis diagnosis and ER+ status appear to be positive predictors of prolonged survival. Conversely, baseline abdominal pain, baseline ascites, and treatment-related grade ≥ 2 toxicity at 3 months after treatment appear to be negative predictors of OS.

Estrogen synthesis in gastric parietal cells and secretion into portal vein.

Aromatase is the enzyme responsible for conversion of C19 androgenic steroids to the corresponding estrogens: a reaction known as aromatization. In systemic circulation, the main source of 17β-estradiol, an estrogen, is the ovary. However, some reports describe that the gastric parietal cells synthesize large amounts of estrogens into the portal vein in both male and female rats. Although the author found many estrogen-producing cells in the stomach of younger and older groups of men and women, details of gastric estrogens have remained unclear. The author therefore investigated the fundamental kinetics of gastric 17β-estradiol using rats, obtaining important findings. In postnatal development, the gastric aromatase increases gradually from 20days after birth. Gastric 17β-estradiol might contribute to liver growth. The regulation of gastric 17β-estradiol differs from that of other gastric endocrine systems and gastric acid secretion. Although ovarian estrogen fluctuates, gastric 17β-estradiol synthesis remains stable during the estrus cycle. The synthesis of gastric 17β-estradiol is independent of the regulatory system of the ovary. The circadian rhythm of the arterial 17β-estradiol level depends on the hepatic estrogen receptor α expression, and also on the concentration of gastric 17β-estradiol in the portal vein because portal venous 17β-estradiol level is synchronized with arterial concentration throughout the day. Liver dysfunction associated with experimental and pathological causes such as portal vein ligation, partial hepatectomy, and bile duct ligation evoke an influx of gastric estrogen into systemic circulation. These findings provide new insights into the gastro-hepatic axis and elucidate stomach and liver functions.

Early-life exposure to 17β-estradiol and 4-nonylphenol impacts the growth hormone/insulin-like growth-factor system and estrogen receptors in Mozambique tilapia, Oreochromis mossambicus

It is widely recognized that endocrine disrupting chemicals (EDCs) released into the environment through anthropogenic activities can have short-term impacts on physiological and behavioral processes and/or sustained or delayed long-term developmental effects on aquatic organisms. While numerous studies have characterized the effects of EDCs on temperate fishes, less is known on the effects of EDCs on the growth and reproductive physiology of tropical species. To determine the long-term effects of early-life exposure to common estrogenic chemicals, we exposed Mozambique tilapia (Oreochromis mossambicus) yolk-sac fry to 17β-estradiol (E2) and nonylphenol (NP) and subsequently characterized the expression of genes involved in growth and reproduction in adults. Fry were exposed to waterborne E2 (0.1 and 1 μg/L) and NP (10 and 100 μg/L) for 21 days. After the exposure period, juveniles were reared for an additional 112 days until males were sampled. Gonadosomatic index was elevated in fish exposed to E2 (0.1 μg/L) while hepatosomatic index was decreased by exposure to NP (100 μg/L). Exposure to E2 (0.1 μg/L) induced hepatic growth hormone receptor (ghr) mRNA expression. The high concentration of E2 (1 μg/L), and both concentrations of NP, increased hepatic insulin-like growth-factor 1 (igf1) expression; E2 and NP did not affect hepatic igf2 and pituitary growth hormone (gh) levels. Both E2 (1 μg/L) and NP (10 μg/L) induced hepatic igf binding protein 1b (igfbp1b) levels while only NP (100 μg/L) induced hepatic igfbp2b levels. By contrast, hepatic igfbp6b was reduced in fish exposed to E2 (1 μg/L). There were no effects of E2 or NP on hepatic igfbp4 and igfbp5a expression. Although the expression of three vitellogenin transcripts was not affected, E2 and NP stimulated hepatic estrogen receptor (erα and erβ) mRNA expression. We conclude that tilapia exposed to E2 and NP as yolk-sac fry exhibit subsequent changes in the endocrine systems that control growth and reproduction during later life stages.

Differential alteration in reproductive toxicity of medaka fish on exposure to nanoscale zerovalent iron and its oxidation products

Nanoscale zerovalent iron (nZVI) is a redox-active nanomaterial commonly used in remediation of soil and groundwater pollution and wastewater treatment processes. A large quantity of nZVI (e.g., >100 mg/L) accidentally released from in situ sites to nearby oxygenized aquifers could be rapidly oxidized to iron oxides (e.g., Fe3O4 or Fe2O3) and ions (e.g., Fe2+), for acute hypoxia effects to aquatic life. However, we do not know the ecotoxicological fate of nZVI and its oxidation products at lower, environmentally concentrations in surface water receiving waterborne transportation or effluent discharge in terms of exposure to aquatic vertebrate species. This study assessed the causal effect on reproductive toxicity in medaka adults (Oryzias latipes) of carboxymethyl cellulose-stabilized nZVI (CMC-nZVI), Fe2+ and iron oxide nanoparticles (nFe3O4) with 21-day aqueous exposure at 5 and 20 mg/L (Fe-equivalent). Such concentrations did not significantly change the dissolved oxygen, oxidation-reduction potential or pH values in the 3 iron solutions during the fish exposure period. Neither CMC-nZVI nor Fe2+ treated adults showed altered daily egg production (fecundity) and oxidative stress responses in observed tissues, as compared to controls. However, the fecundity in nFe3O4 (20 mg/L)-treated pairs was significantly decreased, with increased incidence of abnormal immature oocytes in the ovary. As well, nFe3O4 treatment suppressed activities of the antioxidants superoxide dismutase and expression of glutathione peroxidase (gpx) in the brain and ovary. Although nFe3O4 or Fe2+ treatments inhibited mRNA expression of hepatic estrogen receptor (er-α) in females, plasma levels of sex hormones and (Na, K)-ATPase activity in gills of treated fish did not differ from controls for both sexes. Hence, oxidation products (e.g., nFe3O4) from nZVI at lower milligram-per-liter levels may be potent in inducing nanoparticle-specific reproductive toxicity in medaka fish by inducing oxidative stress in female gonads. Main findingnZVI oxidation product nFe3O4 at lower mg/L induces nanoparticle-specific reproductive toxicity in medaka fish.

Effects of Adrenosterone, Testosterone, and 17β‐Estradiol on the Gene Expression of Insulin‐Like Growth‐Factor Binding Proteins (igfbps) in Atlantic Salmon Smolts

The growth hormone (Gh)/insulin‐like growth‐factor (Igf) system is a key regulator of growth in teleost fishes, including salmonids. Igfs interact with a suite of binding proteins, termed Igf binding proteins (Igfbps), which modify their biological activities. Atlantic salmon (Salmo salar) express an expanded array of igfbp gene transcripts in liver, the primary site of Igfbp production. While gonadal steroids are known to impact the growth of fishes, there is little information on how androgens and estrogens affect the expression of various igfbps. In the current study, we characterized how 14‐day implants of adrenosterone (OA), testosterone (T) or 17β‐estradiol (E2) affected the Gh/Igf/Igfbp network in Atlantic salmon smolts. OA did not affect any of the parameters studied. There were no effects of T or E2 on body mass, plasma levels of Igf1, or hepatic igf1, igf2 or gh receptor mRNA levels. E2 stimulated hepatic estrogen receptor α mRNA levels by 17‐fold, while E2 and T stimulated hepatic vitellogenin mRNA levels by 140‐ and 19‐fold, respectively. Hepatic igfbp1b1 and igfbp4 mRNA levels were diminished by E2 but not T, whereas igfbp2a was diminished by T, but not E2. Alternatively, both T and E2 stimulated igfbp5a. igfbp2b2, igfbp5b2 and igfbp6b were not impacted by any of the tested steroids. Our findings suggest that steroid‐specific effects on the gene expression of various igfbps provide a means for gonadal steroids to modulate the Gh/Igf system.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of metformin and flutamide on insulin, lipogenic and androgen-estrogen signaling, and cardiometabolic risk in a PCOS-prone metabolic syndrome rodent model.

Polycystic ovary syndrome (PCOS) is highly associated with cardiometabolic risk and the metabolic syndrome (MetS), predisposing women to increased risk of developing type 2 diabetes and cardiovascular disease. Metformin is commonly used to treat insulin resistance-glucose intolerance, and flutamide, an androgen receptor (AR) antagonist, is used to target hyperandrogenemia and dyslipidemia. Currently, the physiological mechanism of action of these treatments on androgen, lipidogenic, and insulin signaling pathways remains unclear in PCOS. The aim of this study was to investigate the effects and mechanisms of action of metformin and flutamide on plasma lipid-apolipoprotein (Apo)B-lipoprotein and insulin-glucose metabolism, and endocrine-reproductive indices in a PCOS-prone MetS rodent model. PCOS-prone rodents were treated with metformin (300 mg/kg body wt), flutamide (30 mg/kg body wt), or metformin + flutamide combination treatment for 6 wk. Metformin was shown to improve fasting insulin and HOMA-IR, whereas flutamide and combination treatment were shown to reduce plasma triglycerides, ApoB48, and ApoB100, and this was associated with decreased intestinal secretion of ApoB48/triglyceride. Flutamide and metformin were shown to reduce plasma androgen indices and to improve ovarian primary and preovulatory follicle frequency. Metformin treatment increased hepatic estrogen receptor (ER)α, and metformin-flutamide decreased intestinal AR and increased ERα mRNA expression. Metformin-flutamide treatment upregulated hepatic and intestinal insulin signaling, including insulin receptor, MAPK1, and AKT2. In conclusion, cardiometabolic risk factors, in particular ApoB-hypertriglyceridemia, are independently modulated via the AR, and understanding the contribution of AR and insulin-signaling pathways further may facilitate the development of targeted interventions in high-risk women with PCOS and MetS.

In vivo effects of 17α-ethinylestradiol, 17β-estradiol and 4-nonylphenol on insulin-like growth-factor binding proteins (igfbps) in Atlantic salmon

Feminizing endocrine disrupting compounds (EDCs) affect the growth and development of teleost fishes. The major regulator of growth performance, the growth hormone (Gh)/insulin-like growth-factor (Igf) system, is sensitive to estrogenic compounds and mediates certain physiological and potentially behavioral consequences of EDC exposure. Igf binding proteins (Igfbps) are key modulators of Igf activity, but their alteration by EDCs has not been examined. We investigated two life-stages (fry and smolts) of Atlantic salmon (Salmo salar), and characterized how the Gh/Igf/Igfbp system responded to waterborne 17α-ethinylestradiol (EE2), 17β-estradiol (E2) and 4-nonylphenol (NP). Fry exposed to EE2 and NP for 21 days had increased hepatic vitellogenin (vtg) mRNA levels while hepatic estrogen receptor α (erα), gh receptor (ghr), igf1 and igf2 mRNA levels were decreased. NP-exposed fry had reduced body mass and total length compared to controls. EE2 and NP reduced hepatic igfbp1b1, -2a, -2b1, -4, -5b2 and -6b1, and stimulated igfbp5a. In smolts, hepatic vtg mRNA levels were induced following 4-day exposures to all three EDCs, while erα only responded to EE2 and E2. EDC exposures did not affect body mass or fork length; however, EE2 diminished plasma Gh and Igf1 levels in parallel with reductions in hepatic ghr and igf1. In smolts, EE2 and E2 diminished hepatic igfbp1b1, -4 and -6b1, and stimulated igfbp5a. There were no signs of compromised ionoregulation in smolts, as indicated by unchanged branchial ion pump/transporter mRNA levels. We conclude that hepatic igfbps respond (directly and/or indirectly) to environmental estrogens during two key life-stages of Atlantic salmon, and thus may modulate the growth and development of exposed individuals.

Dietary fish oil replacement by soybean oil: Effect on plasma vitellogenin, sex steroids and ovarian steroidogenesis in Chinese strip-necked turtles (Mauremys sinensis )

In order to investigate the effects of dietary fish oil replacement, the turtles (Mauremys sinensis) were fed four experimental diets for 10 months: FO (100% fish oil), FSO (70% fish oil and 30% soybean oil), SFO (30% fish oil and 70% soybean oil) and SO (100% soybean oil), sampled at pre-vitellogenesis, vitellogenesis and post-vitellogenesis. The results showed that plasma gonadotropin-releasing hormone (GnRH) levels were the highest at pre-vitellogenesis, which promoted the secretion of gonadotropin and sex steroids. Therefore, plasma luteinizing hormone (LH) and estrogen (E2) levels were significantly increased at post-vitellogenesis (p < 0.05), while follicle-stimulating hormone (FSH) levels increased at vitellogenesis (p < 0.05). The FO and FSO groups had significantly higher GnRH and E2 levels than the other two groups (p < 0.05). In addition, plasma vitellogenin (Vtg) levels significantly increased at vitellogenesis and post-vitellogenesis (p < 0.05), which were significantly higher in the groups of FO and FSO than SO (p < 0.05). Moreover, the expression levels of hepatic estrogen receptor α (Erα) mRNA were significantly increased at vitellogenesis and post-vitellogenesis while ovarian Cyp19α1α mRNA were significantly increased at post-vitellogenesis (p < 0.05), and both were the lowest in SO. Taken together, the replacement of fish oil with 66.7% soybean oil is feasible.

Hepatic Estrogen Receptor Expression Prevents Liver Fibrosis through Decreasing the Risk of Early Activation of Hepatic Stellate Cells

Hepatic Estrogen Receptor Expression Prevents Liver Fibrosis through Decreasing the Risk of Early Activation of Hepatic Stellate Cells

Short-Term Fasting Reveals Amino Acid Metabolism as a Major Sex-Discriminating Factor in the Liver

SummarySex impacts on liver physiology with severe consequences for energy metabolism and response to xenobiotic, hepatic, and extra-hepatic diseases. The comprehension of the biology subtending sex-related hepatic differences is therefore very relevant in the medical, pharmacological, and dietary perspective. The extensive application of metabolomics paired to transcriptomics here shows that, in the case of short-term fasting, the decision to maintain lipid synthesis using amino acids (aa) as a source of fuel is the key discriminant for the hepatic metabolism of male and female mice. Pharmacological and genetic interventions indicate that the hepatic estrogen receptor (ERα) has a key role in this sex-related strategy that is primed around birth by the aromatase-dependent conversion of testosterone into estradiol. This energy partition strategy, possibly the result of an evolutionary pressure enabling mammals to tailor their reproductive capacities to nutritional status, is most important to direct future sex-specific dietary and medical interventions.

Maternal lipopolysaccharide exposure results in glucose metabolism disorders and sex hormone imbalance in male offspring.

An adverse intrauterine environment may be an important factor contributing to the development of type 2 diabetes in later life. The present study investigated the longitudinal effects of maternal lipopolysaccharide (LPS) exposure during the third trimester on glucose metabolism and sex hormone balance in the offspring. Pregnant mice were intraperitoneally injected with LPS (50 μg/kg) daily from gestational day (GD) 15 to GD17. Glucose tolerance test (GTT) and insulin tolerance test (ITT) were assessed at postnatal day (PND) 60 and PND120. Sex hormones, their receptors, and metabolic enzymes (aromatase) were measured in male offspring at different phases of development (PND14: juvenile; PND35: adolescence; PND60: adulthood; and PND120: middle age). LPS-exposed male offspring exhibited glucose intolerance and insulin resistance by GTT and ITT at middle age, accompanied by an increase in fasting blood glucose and reductions in serum insulin levels and hepatic phosphorylated (p) -AKT/AKT ratio. However, glucose intolerance and insulin resistance were not observed in LPS-exposed female offspring. Maternal LPS exposure upregulated hepatic aromatase proteins and mRNA levels in male offspring at all time points. At adolescence, the testosterone/estradiol ratio (T/E2) was markedly reduced in LPS-exposed male offspring. Moreover, maternal LPS exposure significantly increased hepatic estrogen receptor (ER) α expressions and decreased hepatic androgen receptor (AR) expressions in male offspring. At adulthood, maternal LPS exposure increased serum estradiol levels, decreased serum testosterone levels and elevated hepatic ERβ expressions in male offspring. In conclusion, maternal LPS exposure upregulated aromatase expressions, followed by a reduction in the T/E2 ratio and an alteration in sex hormone receptor activity, which might be involved in the development of glucose metabolism disorders in middle-aged male offspring. This study provides a novel clue and direction to clarify the pathogenesis of maternal infection-related diabetes in male offspring.

Immune-Specific Expression and Estrogenic Regulation of the Four Estrogen Receptor Isoforms in Female Rainbow Trout (Oncorhynchus mykiss).

Genomic actions of estrogens in vertebrates are exerted via two intracellular estrogen receptor (ER) subtypes, ERα and ERβ, which show cell- and tissue-specific expression profiles. Mammalian immune cells express ERs and are responsive to estrogens. More recently, evidence became available that ERs are also present in the immune organs and cells of teleost fish, suggesting that the immunomodulatory function of estrogens has been conserved throughout vertebrate evolution. For a better understanding of the sensitivity and the responsiveness of the fish immune system to estrogens, more insight is needed on the abundance of ERs in the fish immune system, the cellular ratios of the ER subtypes, and their autoregulation by estrogens. Consequently, the aims of the present study were (i) to determine the absolute mRNA copy numbers of the four ER isoforms in the immune organs and cells of rainbow trout, Oncorhynchus mykiss, and to compare them to the hepatic ER numbers; (ii) to analyse the ER mRNA isoform ratios in the immune system; and, (iii) finally, to examine the alterations of immune ER mRNA expression levels in sexually immature trout exposed to 17β-estradiol (E2), as well as the alterations of immune ER mRNA expression levels in sexually mature trout during the reproductive cycle. All four ER isoforms were present in immune organs—head kidney, spleen-and immune cells from head kidney and blood of rainbow trout, but their mRNA levels were substantially lower than in the liver. The ER isoform ratios were tissue- and cell-specific, both within the immune system, but also between the immune system and the liver. Short-term administration of E2 to juvenile female trout altered the ER mRNA levels in the liver, but the ERs of the immune organs and cells were not responsive. Changes of ER gene transcript numbers in immune organs and cells occurred during the reproductive cycle of mature female trout, but the changes in the immune ER profiles differed from those in the liver and gonads. The correlation between ER gene transcript numbers and serum E2 concentrations was only moderate to low. In conclusion, the low mRNA numbers of nuclear ER in the trout immune system, together with their limited estrogen-responsiveness, suggest that the known estrogen actions on trout immunity may be not primarily mediated through genomic actions, but may involve other mechanisms, such as non-genomic pathways or indirect effects.

STAT6, PBX2, and PBRM1 Emerge as Predicted Regulators of 452 Differentially Expressed Genes Associated With Puberty in Brahman Heifers.

The liver plays a central role in metabolism and produces important hormones. Hepatic estrogen receptors and the release of insulin-like growth factor 1 (IGF1) are critical links between liver function and the reproductive system. However, the role of liver in pubertal development is not fully understood. To explore this question, we applied transcriptomic analyses to liver samples of pre- and post-pubertal Brahman heifers and identified differentially expressed (DE) genes and genes encoding transcription factors (TFs). Differential expression of genes suggests potential biological mechanisms and pathways linking liver function to puberty. The analyses identified 452 DE genes and 82 TF with significant contribution to differential gene expression by using a regulatory impact factor metric. Brain-derived neurotrophic factor was observed as the most down-regulated gene (P = 0.003) in post-pubertal heifers and we propose this gene influences pubertal development in Brahman heifers. Additionally, co-expression network analysis provided evidence for three TF as key regulators of liver function during pubertal development: the signal transducer and activator of transcription 6, PBX homeobox 2, and polybromo 1. Pathway enrichment analysis identified transforming growth factor-beta and Wnt signaling pathways as significant annotation terms for the list of DE genes and TF in the co-expression network. Molecular information regarding genes and pathways described in this work are important to further our understanding of puberty onset in Brahman heifers.