Administration Of 17β-estradiol Research Articles

Female sex hormones inversely regulate acute kidney disease susceptibility throughout life.

While epidemiological and experimental studies have demonstrated kidney-protective effects of estrogen and female sex in adulthood, some epidemiological data showed deterioration of kidney function during puberty when estrogen production increases. However, molecular mechanisms explaining these conflicting phenomena remain unknown. Here, we showed that the pubertal sex hormone surge in female mice increases susceptibility to kidney ischemia reperfusion injury partly via downregulation of insulin-like growth factor 1 receptor (IGF-1R) expression in proximal tubules. Adult mice ovariectomized pre-pubertally (at postnatal day 21) showed strong tolerance to kidney ischemia, which was partly reversed by the administration of 17β-estradiol, while adult mice ovariectomized post-pubertally (at 8 weeks of age) were vulnerable to kidney ischemia. Kidney tubular IGF-1R protein expression decreased during postnatal growth but was highly expressed in adult mice ovariectomized pre-pubertally and in infant mice, which might be partly explained by different expression of an E3 ligase (MDM2) of IGF-1R. Mice deficient of Igf-1r in proximal tubules (iIGF-1RKO mice) during postnatal kidney growth showed increased susceptibility to ischemic injury. RNA-seq and western blotting analysis using proximal tubular cells from pre-pubertally ovariectomized iIGF-1RKO and control mice revealed altered expression of cell cycle-associated molecules such as cyclin D1. These results suggest that Igf-1r deletion during postnatal growth renders proximal tubular cells susceptible to ischemia possibly via altered cell cycle regulation. Thus, our findings provide evidence that exposure to pubertal sex hormones leads to increased susceptibility to kidney ischemia, which is partly mediated by modulation of IGF-1R signaling.

Comparison of pain modulatory effect of the LPGi estragon receptor on inflammatory pain between pro-estrus and estrus phases and OVX rats.

The present study has investigated whether circulating estrogen level variations in the pro-estrus and estrus phases of the intact rats and estrogen depletion in the ovariectomized animals (OVX) adjust the formalin-induced nociceptive behaviors. During the pro-estrus and estrus phases of rats' estrus cycle and in the OVX rats, 17β-estradiol and ICI 182,780 (estrogen receptor antagonist) were administered into the right paragigantocellularis lateralis (LPGi) nucleus. Then, the formalin-induced flexing and licking responses were recorded for 60min. The findings of this study revealed that intra-LPGi administration of 17β-estradiol (0.8μmol) reduced the formalin-induced flexing and licking duration in pro-estrus and estrus rats (P < 0.001), suggesting an analgesic effect. 17β-Estradiol injection into the LPGi nucleus of OVX rats increased the flexing duration (P < 0.05) while decreasing the licking duration (P < 0.05) of the formalin test. The pain modulatory effect of 17β-estradiol on the flexing response was reversed by ICI 182,780 (15nmol) in the pro-estrus (P < 0.001) and estrus rats (P < 0.001) but not in the OVX rats. Also, pretreatment of LPGi nucleus with ICI 182,780 reversed the analgesic effect of 17β-estradiol on the licking response in the pro-estrus (P < 0.05), estrus (P < 0.001), and OVX rats (P < 0.001). These results suggest that the pain threshold in intact female rats is modulated independently of the estrus state. Still, the basal level of plasma estrogen and the activation of its receptors are necessary for pain modulation.

Sex Differences of Neutrophil Extracellular Traps on Lipopolysaccharide-Stimulated Human Neutrophils.

Objective: Sex differences exist in sepsis, but the commitment of neutrophils to these differences remains unclear. Neutrophil extracellular traps (NETs) function to remove pathogens, yet excessive NETs release can contribute to organ damage. This study explores effects of the gender hormones on endotoxin-induced NETs using neutrophils from both male and female sources. Methods: Blood samples were collected from healthy volunteers. Isolated neutrophils were seeded in collagen-coated cell culture plates, and NETs were induced by lipopolysaccharide (LPS) treatment. After 15 minutes of LPS treatment, 17β-estradiol (0.03-272.4 ng/mL), testosterone enanthate (0.01-10 ng/mL), dimethyl sulfoxide, or ethanol (vehicle control) was added to the plates. These were incubated for three hours at 37°C with 5% CO2. Neutrophil extracellular traps formation was assessed using immunofluorescence staining. Results: Lipopolysaccharide-induced NETs formation was significantly greater in females than in males. In male-derived neutrophils, 17β-estradiol at above the blood concentrations significantly suppressed LPS-induced NETs. No effect was seen while using testosterone enanthate to NETs at any concentration. In female-derived neutrophils, 17β-estradiol, which was near to the highest concentration of non-pregnant women's blood, tended to increase NETs. Testosterone enanthate, which was near to female blood concentration, significantly promoted NETs. Conclusions: Sex differences existed in LPS-induced NETs of human neutrophil. In males, high concentrations of 17β-estradiol administration may have a suppressive effect on excessive NETs during infection. In females, endogenous gender hormones may promote NETs during infection. Sex differences in neutrophils may need to be considered in organ damage owing to NETs excess such as sepsis.

17β-Estradiol reduces inhibitory synaptic currents in entorhinal cortex neurons through G protein-coupled estrogen receptor-1 activation of extracellular signal-regulated kinase.

Estrogens are believed to modulate cognitive functions in part through the modulation of synaptic transmission in the cortex and hippocampus. Administration of 17β-estradiol (E2) can rapidly enhance excitatory synaptic transmission in the hippocampus and facilitate excitatory synaptic transmission in rat lateral entorhinal cortex via activation of the G protein-coupled estrogen receptor-1 (GPER1). To assess the mechanisms through which GPER1 activation facilitates synaptic transmission, we assessed the effects of acute 10 nM E2 administration on pharmacologically isolated evoked excitatory and inhibitory synaptic currents in layer II/III entorhinal neurons. Female Long-Evans rats were ovariectomized between postnatal day (PD) 63 and 74 and implanted with a subdermal E2 capsule to maintain continuous low levels of E2. Electrophysiological recordings were obtained between 7 and 20 days after ovariectomy. Application of E2 for 20 min did not significantly affect AMPA or NMDA receptor-mediated excitatory synaptic currents. However, GABA receptor-mediated inhibitory synaptic currents (IPSCs) were markedly reduced by E2 and returned towards baseline levels during the 20-min washout period. The inhibition of GABA-mediated IPSCs was blocked in the presence of the GPER1 receptor antagonist G15. GPER1 can modulate protein kinase A (PKA), but blocking PKA with intracellular KT5720 did not prevent the E2-induced reduction in IPSCs. GPER1 can also stimulate extracellular signal-regulated kinase (ERK), a negative modulator of GABAA receptors, and blocking activation of ERK with PD90859 prevented the E2-induced reduction of IPSCs. E2 can therefore result in a rapid GPER1 and ERK signaling-mediated reduction in GABA-mediated IPSCs. This provides a novel mechanism through which E2 can rapidly modulate synaptic excitability in entorhinal layer II/III neurons and may also contribute to E2 and ERK-dependent alterations in synaptic transmission in other brain areas.

Impact of 17β-estradiol administration at the moment of timed-AI in Nelore cows with small dominant follicle or not showing estrus

We aimed to evaluate the effects of administering estradiol (E−17β) at the moment of timed-AI (TAI) on uterine gene expression, estrous expression rate (EER), and pregnancy rate (P/TAI) in Nelore cows with a small dominant follicle (DF) or not showing estrus at TAI. In Experiments 1 and 2 (Exp1, Exp2) cows were submitted to a P4/E−17β-based protocol (day 0) for synchronization of ovulation. On day 7, devices were removed, cows received 1 mg E−17β cypionate and 12.5 mg dinoprost. On day 9, cows with DF < 11.5 mm in diameter were split into different groups. In Exp1 (n = 16/group): Control (no treatment), E−2 (2 mg E−17β) and E−4 (4 mg E−17β). In Exp2: Control (n = 12); E−2 (n = 14); GnRH (0.1 mg gonadorelin acetate, n = 13); and E−2+GnRH (association of GnRH and E−17β, n = 13). Between days 9 and 11, endometrial thickness (ET), time of ovulation detection, and EER were recorded. In Exp1, a uterine cytological sample was collected 4 h after treatment to evaluate the transcript expression of receptors for E−17β (ESR1 and ESR2), oxytocin (OXTR), and P4 (PGR). In Experiment 3 (Exp3), 3829 suckled cows were submitted to a P4/E−17β-based protocol for TAI. On day 9, devices were removed and cows received 1 mg E−17β cypionate and 0.4 mg sodium cloprostenol. On day 11, TAI was performed and cows that did not demonstrate estrus received 0.1 mg gonadorelin acetate, and were allocated into two groups: GnRH (n = 368) and E−2+GnRH (2 mg E−17β; n = 363). In Exp1, plasma E−17β concentrations increased at 4 h after treatment in a dose-dependent manner but reduced at 12 h. The E−17β-treated cows had greater transcript abundance for OXTR and lesser for ESR1 and ESR2, and the ET was reduced 12 h after treatment (P < 0.05). No significant difference (P > 0.1) was observed between the E−17β doses in estrus or ovulation rate. In Exp2, the interval from treatment to ovulation was longer (P < 0.05) in the E−17β group. GnRH-treated cows showed higher ovulation rates (89 vs. 35 %) compared to cows not treated with GnRH, as E−17β-treated cows (P < 0.01) had a lower ovulation rate compared to those not receiving E−17β (44 vs. 78 %). In Exp3, P/TAI was 55 % for cows in estrus. For those not showing estrus, no difference (P > 0.1) in P/TAI was observed between GnRH (34 %) and E−2+GnRH (31 %) groups. Cows with a DF ≥ 11 mm (n = 192) had a greater (P < 0.05) P/TAI (49 %) than those with DF < 11 mm (n = 377; 29 %). In conclusion, E−17β administration in the moment of TAI modulates the mRNA expression of uterine receptors in cows with a small DF but does not impact the P/TAI compared with GnRH treatment in suckled Nelore not showing estrus previous to TAI.

Cannabidiol Alleviates Chronic Prostatitis and Chronic Pelvic Pain Syndrome via CB2 Receptor Activation and TRPV1 Desensitization.

This study elucidates the mechanism of the physiological effect of cannabidiol (CBD) by assessing its impact on lipopolysaccharide (LPS)-induced inflammation in RWPE-1 cells and prostatitis-induced by 17β-estradiol and dihydrotestosterone in a rat model, focusing on its therapeutic potential for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). RWPE-1 cells were stratified in vitro into three groups: (1) controls, (2) cells with LPS-induced inflammation, and (3) cells with LPS-induced inflammation and treated with CBD. Enzyme-linked immunosorbent assays and western blots were performed on cellular components and supernatants after administration of CBD. Five groups of six Sprague-Dawley male rats were assigned: (1) control, (2) CP/CPPS, (3) CP/CPPS and treated with 50 mg/kg CBD, (4) CP/CPPS and treated with 100 mg/kg CBD, and (5) CP/CPPS and treated with 150 mg/kg CBD. Prostatitis was induced through administration of 17β-estradiol and dihydrotestosterone. After four weeks of CBD treatment, a pain index was evaluated, and prostate tissue was collected for subsequent histologic examination and western blot analysis. CBD demonstrated efficacy in vivo for CP/CPPS and in vitro for inflammation. It inhibited the toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway by activating the CB2 receptor, reducing expression of interleukin-6, tumor necrosis factor-alpha, and cyclooxygenase-2 (COX2) (p<0.01). CBD exhibited analgesic effects by activating and desensitizing the TRPV1 receptor. CBD inhibits the TLR4/NF-κB pathway by activating the CB2 receptor, desensitizes the TRPV1 receptor, and decreases the release of COX2. This results in relief of inflammation and pain in patients with CP/CPPS, indicating CBD as a potential treatment for CP/CPPS.

The G-protein-coupled estrogen receptor, a gene co-expressed with ERα in breast tumors, is regulated by estrogen-ERα signalling in ERα positive breast cancer cells

GPER is a seven transmembrane G-protein-coupled estrogen receptor that mediates rapid estrogen actions. Large volumes of data have revealed its association with clinicopathological variables in breast tumors, role in epidermal growth factor (EGF)-like effects of estrogen, potential as a therapeutic target or a prognostic marker, and involvement in endocrine resistance in the face of tamoxifen agonism. GPER cross-talks with estrogen receptor alpha (ERα) in cell culture models implicating its role in the physiology of normal or transformed mammary epithelial cells. However, discrepancies in the literature have obfuscated the nature of their relationship, its significance, and the underlying mechanism. The purpose of this study was to assess the relationship between GPER, and ERα in breast tumors, to understand the mechanistic basis, and to gauge its clinical significance. We mined The Cancer Genome Atlas (TCGA)-BRCA data to examine the relationship between GPER and ERα expression. GPER mRNA, and protein expression were analyzed in ERα-positive or -negative breast tumors from two independent cohorts using immunohistochemistry, western blotting, or RT-qPCR. The Kaplan-Meier Plotter (KM) was employed for survival analysis. The influence of estrogen in vivo was studied by examining GPER expression levels in estrus or diestrus mouse mammary tissues, and the impact of 17β-estradiol (E2) administration in juvenile or adult mice. The effect of E2, or propylpyrazoletriol (PPT, an ERα agonist) stimulation on GPER expression was studied in MCF-7 and T47D cells, with or without tamoxifen or ERα knockdown. ERα-binding to the GPER locus was explored by analysing ChIP-seq data (ERP000380), in silico prediction of estrogen response elements, and chromatin immunoprecipitation (ChIP) assay. Clinical data revealed significant positive association between GPER and ERα expression in breast tumors. The median GPER expression in ERα-positive tumors was significantly higher than ERα-negative tumors. High GPER expression was significantly associated with longer overall survival (OS) of patients with ERα-positive tumors. In vivo experiments showed a positive effect of E2 on GPER expression. E2 induced GPER expression in MCF-7 and T47D cells; an effect mimicked by PPT. Tamoxifen or ERα-knockdown blocked the induction of GPER. Estrogen-mediated induction was associated with increased ERα occupancy in the upstream region of GPER. Furthermore, treatment with 17β-estradiol or PPT significantly reduced the IC50 of the GPER agonist (G1)-mediated loss of MCF-7 or T47D cell viability. In conclusion, GPER is positively associated with ERα in breast tumors, and induced by estrogen-ERα signalling axis. Estrogen-mediated induction of GPER makes the cells more responsive to GPER ligands. More in-depth studies are warranted to establish the significance of GPER-ERα co-expression, and their interplay in breast tumor development, progression, and treatment.

The influence of 17β-estradiol plus norethisterone acetate treatment on markers of glucose and insulin metabolism in women: a systematic review and meta-analysis of randomized controlled trials.

Despite the fact that some evidence suggests that the administration of 17β-estradiol plus norethisterone acetate influences glucose and insulin metabolism in women, these findings are still contradictory. Thus, we aimed to examine the impact of the co-administration of 17β-estradiol and norethisterone acetate on glycated haemoglobin (HbA1c), fasting glucose, insulin and C-peptide concentrations in females by means of a systematic review and meta-analysis of randomized controlled trials (RCTs). We searched four databases (PubMed/MEDLINE, Scopus, Embase, and Web of Science) using specific keywords and word combinations. The random-effects model (DerSimonian and Laird model) was employed to compute the weighted mean difference (WMD) and 95% confidence intervals (CIs) for the variations from baseline of HbA1c, fasting glucose, insulin, and C-peptide concentrations. In total, 14 RCTs were entered into the quantitative synthesis. The combined administration of 17β-estradiol and norethisterone acetate decreased HbA1c (WMD: -0.65%, 95% CI: -1.15 to -0.15; P=0.011), fasting glucose (WMD: -11.05 mg/dL, 95% CI: -16.6 to -5.5; P<0.001) and insulin (WMD: -1.35 mIU/L, 95% CI: -2.20 to -0.50; P=0.001) levels. C-peptide concentrations' declined only in females diagnosed with overweight/obesity or diabetes. Evidence to date points out that the administration of 17β-estradiol and norethisterone acetate has a positive impact on glucose metabolism in women by reducing fasting glucose, HbA1c, and insulin values. Future studies need to confirm the potential benefits of this drug combination in the prevention and/or management of cardiometabolic disorders.

Characterization of Early Gonadal Differentiation and Induction of Sex Reversal in the Rock Bream Oplegnathus fasciatus.

Rock bream (Oplegnathus fasciatus) is a typical fish that has a unique multiple sex chromosome system (♀X1X1X2X2/♂X1X2Y). We examined the early gonadal development in rock bream via continuous histological observations of the gonads at 40-120days post hatching (dph). The fish was identified as a typical gonochorist, and female gonads were found to differentiate earlier than male gonads. The ovarian cavity of the female was initially observed at 80 dph, whereas the efferent duct of the male was not observed until 100 dph. Immunofluorescence with the vasa-antibody revealed that germ cells were predominantly distributed around the ovarian cavity in females and on the edge of the gonad in males during the early stages of sex differentiation. Sex reversal was induced via the oral administration of letrozole (LTZ), 17α-methyltestosterone (MT), and 17β-estradiol (E2), respectively, during the labile period of gonadal development. LTZ and MT induced 100% masculinization of genotype-females, whereas E2 induced only 50-60% feminization of genotype-males. Such findings suggest that the fish retained high sexual plasticity despite the existence of the neo-Y chromosome. MT and E2 had negative effect on fish growth, whereas LTZ did not exert such side effect. LTZ and MT could accelerate gonadal development in sex-reversed genotype-males, whereas E2 inhibited gonadal development in genotype-females of rock bream. These findings provide a basis for further research on the mechanisms of sex determination and differentiation in fishes with X1X2Y sex chromosome system and provide a sex reversal protocol for rock bream.

Premature Death of Sleep Fragmented Males is Associated With An Accumulation of Reactive Oxygen Species In The Gut

Abstract 70 million Americans report insufficient sleep due to work or lifestyle choices. Decreased duration and poor sleep quality are associated with high rates of CVD and is strongly associated with increased risk of all-cause mortality. The effects of gender have been studied in CVD, but the impact of sexual dimorphism in Sleep Fragmented (SF)-associated atherogenesis is not known. Recently, we found that high fat diet (HFD) fed male Apoe −/−mice on SF experienced premature death. 80% of males did not survive past week 2 of SF, while 80% of females survived past week 8 under same conditions. We sought to identify a cause of premature death in HFD fed male Apoe −/−mice following sleep fragmentation. Interestingly, HFD fed male Ldlr −/−mouse did not experience premature death when SF, suggesting that ApoE absence, not hyperlipidemia, plays an essential function in the induction of death. Furthermore, oral 17β-Estradiol was able to rescue HFD fed male Apoe −/−mice from SF induced premature death. Compared to controls, SF, HFD fed male Apoe −/−mice had decreased body weight and increased circulating LPS, ROS and cell-free dsDNA at death. Finally, the small intestines SF, HFD fed male Apoe −/−mice had increased ROS and decreased tight junction protein (Tjp1) expression, suggesting compromised intestinal barrier function. Our data suggests that a combination of known risk factors for CVD (male sex, ApoE genotype, and HFD) results in premature death when combined with inadequate sleep. Furthermore, our data suggests that this specific combination of co-factors might result in premature death due to a systemic increase in oxidative stress, possibly caused by leakage of LPS from the gut, which may be alleviated through the administration of 17β-Estradiol. Supported by project–initiation funds from the Center for Integrative Neuroscience and Inflammatory Diseases and AHA Predoctoral (20PRE35180156)

Modified Estrogen-Progesterone Induction Method of Mammary Gland Hyperplasia in Rats.

In female Wistar rats, mammary gland hyperplasia (MGH) was modeled according to a modified protocol involving estrogen-progesterone induction and taking into account the duration of the estrous cycle of this animal species. MGH was induced over four 7-day cycles; each cycle included subcutaneous administration of 17β-estradiol (0.5 mg/kg) for 4 days, injection of progesterone (5 mg/kg) on day 5, then 2 days without injections. In females with MGH, a significant increase in the height and diameter of the nipples of the mammary glands was recorded, two types of changes were observed in the gland tissue: tubuloalveolar and lobuloalveolar hyperplasia. The study confirmed the development of MGH in rats by a modified method.

Differential expression of desmin in the uterine myometrium and cervix as a possible mechanism for successful parturition in rats.

Expression of desmin, an intermediate filament, in the myometrium and cervix were investigated in peripartum rats (full term day 22 of pregnancy (DP22)). Des mRNA was expressed in lesser amounts in the cervix at peripartum (DP17 and 21, and day of birth 1 (DB1)), compared to those in the cervixes of ovariectomized rats. Immunohistochemical analysis revealed that desmin protein was diffusely present in the myometrium, and locally in the epithelium of the cervix. Western blot analysis showed that desmin protein levels in the myometrium increased 4- to 6-fold at DP17, 21 and DB1, and decreased rapidly at DB2 to the basal level observed in ovariectomized or non-pregnant rats. In contrast, cervical desmin protein levels increased approximately 10-fold at DP21 compared to those in ovariectomized rats, but decreased rapidly at DB1, indicating its decrease at parturition and an inconsistency between mRNA and protein expression. The administration of 17β-estradiol to ovariectomized rats increased desmin protein levels in the myometrium and cervix after 24h. S-nitrosylated desmin protein was detected in the myometrium and cervix at DP21. The mRNA expression of inducible nitric oxide synthase was consistent with the expression of desmin protein. Thus, desmin, which is regulated by estradiol, is differentially expressed in the myometrium and cervix at peripartum possibly for successful pregnancy and parturition. In the cervix, desmin protein expression seems to be regulated by estradiol at the translational level. S-nitrosylation of desmin may have a potential role in the peripartum uterus.

Evaluation of pharmacokinetics and safety of a long-term estradiol-releasing stent in rat uterine.

PurposeIntrauterine adhesion (IUA), often leading to gynecological complications including amenorrhea, abdominal pain and infertility, is frequently induced by injuries to the endometrium. Hence it would be of great benefit to take efforts to prevent adhesion after intrauterine operations. Orally administration of 17β-estradiol (E2) is commonly used to promote endometrium regeneration, but is limited by low concentrations at the injured sites. We aim at preparing an E2-releasing uterine stent, which could improve the efficiency of E2 therapy and be utilized for IUA prevention.MethodsWe designed a silicone rubber stent, which could be implanted in the uterine cavity and continuously release E2 in long term. Stents were placed in rodent uterine, and removed at different time points. Remaining E2 in stent was measured by high performance liquid chromatography (HPLC), and organ E2 concentrations were detected by enzyme-linked immuno sorbent assay (ELISA). Endometrium morphology was examined by histological staining of paraffin sections.ResultsOur stent showed a controlled release of E2 in rodent uterine for over 60 days, and significantly increased E2 concentration in serum and in situ uterine. After the stent was removed from uterine, E2 rapidly reverted to a normal level. Also, the stent did not induce pathological changes in endometrium.ConclusionsThe uterine stent provided abundant local E2 in uterine cavity with satisfactory safety. The silicone rubber based E2-releasing uterine stent could be further advanced by adjusting its shape and E2 load for its clinical application, and might promisingly help lowering the incidence of IUA.

Effect of chronic administration of 17β-estradiol on the vasopressor responses induced by the sympathetic nervous system in insulin resistance rats

Several studies have demonstrated that the underlying mechanism of insulin resistance (IR) is linked with developing diseases like diabetes mellitus, hypertension, metabolic syndrome, and polycystic ovary syndrome. In turn, the dysfunction of female gonadal hormones (especially 17β-estradiol) may be related to the development of IR complications since different studies have shown that 17β-estradiol has a cardioprotector and vasorelaxant effect. This study aimed was to determine the effect of the 17β-estradiol administration in insulin-resistant rats and its effects on cardiovascular responses in pithed rats. Thus, the vasopressor responses are induced by sympathetic stimulation or i.v. bolus injections of noradrenaline (α1/2), methoxamine (α1), and UK 14,304 (α2) adrenergic agonist were determined in female pithed rats with fructose-induced insulin resistance or control rats treated with: 1) 17β-estradiol or 2) its vehicle (oil) for 5 weeks. Thus, 17β-estradiol decreased heart rate, prevented the increase of blood pressure induced by ovariectomy, but with the opposite effect on sham-operated rats; and decreased vasopressor responses induced by i.v. bolus injections of noradrenaline on sham-operated (control and fructose group) and ovariectomized (control) rats, and those induced by i.v. bolus injections of methoxamine (α1 adrenergic agonist). Overall, these results suggest 17β-estradiol has a cardioprotective effect, and its effect on vasopressor responses could be mediated mainly by the α1 adrenergic receptor. In contrast, IR with ovariectomy 17β-estradiol decreases or loses its cardioprotector effect, this could suggest a possible link between the adrenergic receptors and the insulin pathway.

The effect of 17β-estradiol plus norethisterone acetate treatment on the lipid profile in women: a dose-response meta-analysis of randomized controlled trials.

The impact of 17β-estradiol plus norethisterone acetate administration on serum lipids in women is controversial as previously published studies have produced conflicting results. Thus, we conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to investigate the effects of 17β-estradiol plus norethisterone acetate therapy on total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) in females. We searched the PubMed/MEDLINE, Scopus, Embase, and Web of Science databases for relevant trials published in English until 15 July 2021. The weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated using a random-effects model (the DerSimonian and Laird methods). A total of 32 RCTs were included in the final analysis. Treatment with 17β-estradiol plus norethisterone acetate significantly decreased LDL-C (WMD: -13.49 mg/dL, 95% CI: -16.46 to -10.52; P < 0.001), HDL-C (WMD: -3.57 mg/dL, 95% CI: -5.56 to -1.58; P < 0.001), TC (WMD: -19.33 mg/dL, 95% CI: -24.14 to -14.52; P < 0.001), and TG (WMD: -10.86 mg/dL, 95% CI: -16.06 to -5.13; P < 0.001) levels in females. The non-linear dose-response meta-analysis revealed a negative correlation between HDL-C levels and increased treatment periods (P ˂ 0.001). Evidence to date suggests that the administration of 17β-estradiol plus norethisterone acetate in females reduces LDL-C, HDL-C, TC, and TG concentrations. Future investigations should clarify whether the reduction in HDL-C following the administration of 17β-estradiol plus norethisterone acetate is clinically significant and poses any risks to the subjects who receive this treatment.

Aromatase Inhibitors Induce Painful-like Musculoskeletal Symptoms in Mice: Behavioral, Molecular and Cellular Characterization

Breast cancer is the second most common cancer among women in the U.S. Most tumors are hormone-receptor positive, and patients receive adjuvant endocrine treatment with aromatase inhibitors (AI) to prolong disease-free survival and time-to-recurrence. Unfortunately, AI-associated musculoskeletal symptoms (AIMSS) such as joint pain and muscle stiffness/achiness is a common side-effect of AIs and approximately one-fourth of patients discontinue their therapy because of these side effects. The precise mechanisms of AIMSS are unknown and no clearly recognized therapies exist for prevention or treatment. We therefore characterized a mouse model of AI-induced AIMSS. C57BL/6J adult ovariectomized female mice received oral letrozole (0.5 mg/kg once/day for 15 days). Mice were then evaluated for multiple evoked and spontaneous nociceptive and pain-like behaviors. We also determined if supplementation of 17β-estradiol will reverse AIMSS behaviors. The effects of ketoprofen and duloxetine were tested in this model also. Female mice treated with letrozole show significant mechanical hypersensitivity, disruption of nesting behaviors and reduction of voluntary wheel running as well as rearing and burrowing behaviors. In addition, letrozole-treated DRG neurons showed enhanced excitability compared to vehicle-treated mice. Finally, a significant increase in expression levels of pro-inflammatory cytokines IL-1β, TNFα and IL-6 were observed in the DRGs of mice treated with letrozole. Administration of 17β-estradiol partially reversed these behavioral signs. Furthermore, contrary to ketoprofen, duloxetine showed effectiveness in the model and showed significant preference in the CPP test in letrozole-treated mice but not vehicle group. Our results suggest the AI letrozole induces painful AIMSS symptoms in mice that are partially mediated by estrogens. In addition, our results suggest peripheral neuronal hyperexcitability driven by proinflammatory cytokines at the DRG levels. These results enhance our understanding of AIMSS and facilitate development of novel therapies to treat AIMSS, thereby reducing discontinuation of this breast cancer therapy. Funds from VCU School of Medicine and Massey Cancer Center.

Estrogen upregulates the firing activity of hypothalamic gonadotropin-releasing hormone (GnRH1) neurons in the evening in female medaka.

The reproductive function of vertebrates is regulated by the hypothalamic-pituitary-gonadal axis. In sexually mature females, gonadotropin-releasing hormone (GnRH) neurons in the preoptic area (POA) are assumed to be responsible for a cyclic large increase in GnRH release, the GnRH surge, triggering a luteinizing hormone (LH) surge, which leads to ovulation. Precise temporal regulation of the preovulatory GnRH/LH surge is important for successful reproduction because ovulation should occur after follicular development. The time course of the circulating level of estrogen is correlated with the ovulatory cycle throughout vertebrates. However, the neural mechanisms underlying estrogen-induced preovulatory GnRH surge after folliculogenesis still remain unclear, especially in non-mammals. Here, we used a versatile non-mammalian model medaka for the analysis of the involvement of estrogen in the regulation of POA-GnRH (GnRH1) neurons. Electrophysiological analysis using a whole brain-pituitary in vitro preparation, which maintains the hypophysiotropic function of GnRH1 neurons intact, revealed that 17β-estradiol (E2 ) administration recovers the ovariectomy-induced lowered GnRH1 neuronal activity in the evening, indicating the importance of E2 for upregulation of GnRH1 neuronal activity. The importance of E2 was also confirmed by the fact that GnRH1 neuronal activity was low in short-day photoperiod-conditioned females (low E2 model). However, E2 failed to upregulate the firing activity of GnRH1 neurons in the morning, suggesting the involvement of additional time-of-day signal(s) for triggering GnRH/LH surges at an appropriate timing. We also provide morphological evidence for the localization of estrogen receptor subtypes in GnRH1 neurons. In conclusion, we propose a working hypothesis in which both estrogenic and time-of-day signals act in concert to timely upregulate the firing activity of GnRH1 neurons that trigger the GnRH surge at an appropriate timing in a female-specific manner. This neuroendocrinological mechanism is suggested to be responsible for the generation of ovulatory cycles in female teleosts in general.

Estrogen signaling modulates behavioral selection toward pups and amygdalohippocampal area in the rhomboid nucleus of the bed nucleus of the stria terminalis circuit

Gonadal steroid hormone influences behavioral choice of adult animals toward pups, parental or aggressive. We previously reported that long-term administration of 17β-estradiol (E2) to male mice during sexual maturation induces aggressive behavior toward conspecific pups, which is called “infanticide,” and significantly enhanced excitatory synaptic transmission in the rhomboid nucleus of bed nucleus of the stria terminalis (BSTrh), which is an important brain region for infanticide. However, it is unclear how estrogen receptor–dependent signaling after sexual maturity regulates neural circuits including the BSTrh. Here we revealed that E2 administration to gonadectomized mice in adulthood elicited infanticidal behavior and enhanced excitatory synaptic transmission in the BSTrh by increasing the probability of glutamate release from the presynaptic terminalis. Next, we performed whole-brain mapping of E2-sensitive brain regions projecting to the BSTrh and found that amygdalohippocampal area (AHi) neurons that project to the BSTrh densely express estrogen receptor 1 (Esr1). Moreover, E2 treatment enhanced synaptic connectivity in the AHi-BSTrh pathway. Together, these results suggest that reinforcement of excitatory inputs from AHi neurons into the BSTrh by estrogen receptor–dependent signaling may contribute to the expression of infanticide.

17β-Estradiol Abrogates Oxidative Stress and Neuroinflammation after Cortical Stab Wound Injury.

Disruptions in brain energy metabolism, oxidative damage, and neuroinflammation are commonly seen in traumatic brain injury (TBI). Microglial activation is the hallmark of neuroinflammation. After brain injury, microglia also act as a double-edged sword with distinctive phenotypic changes. Therefore, therapeutic applications to potentiate microglia towards pro-inflammatory response following brain injury have become the focus of attention in recent years. Here, in the current study, we investigated the hypothesis that 17β-estradiol could rescue the mouse brain against apoptotic cell death and neurodegeneration by suppressing deleterious proinflammatory response probably by abrogating metabolic stress and oxidative damage after brain injury. Male C57BL/6N mice were used to establish a cortical stab wound injury (SWI) model. Immediately after brain injury, the mice were treated with 17β-estradiol (10 mg/kg, once every day via i.p. injection) for one week. Immunoblotting and immunohistochemical analysis was performed to examine the cortical and hippocampal brain regions. For the evaluation of reactive oxygen species (ROS), reduced glutathione (GSH), and oxidized glutathione (GSSG), we used specific kits. Our findings revealed that 17β-estradiol treatment significantly alleviated SWI-induced energy dyshomeostasis and oxidative stress by increasing the activity of phospho-AMPK (Thr172) and by regulating the expression of an antioxidant gene (Nrf2) and cytoprotective enzymes (HO-1 and GSH) to mitigate ROS. Importantly, 17β-estradiol treatment downregulated gliosis and proinflammatory markers (iNOS and CD64) while significantly augmenting an anti-inflammatory response as evidenced by the robust expression of TGF-β and IGF-1 after brain injury. The treatment with 17β-estradiol also reduced inflammatory mediators (Tnf-α, IL-1β, and COX-2) in the injured mouse. Moreover, 17β-estradiol administration rescued p53-associated apoptotic cell death in the SWI model by regulating the expression of Bcl-2 family proteins (Bax and Bcl-2) and caspase-3 activation. Finally, SWI + 17β-estradiol-treated mice illustrated reduced brain lesion volume and enhanced neurotrophic effect and the expression of synaptic proteins. These findings suggest that 17β-estradiol is an effective therapy against the brain secondary injury-induced pathological cascade following trauma, although further studies may be conducted to explore the exact mechanisms.

Protein synthesis and actin polymerization in the rapid effects of 17β-estradiol on short-term social memory and dendritic spine dynamics in female mice

Estrogens rapidly facilitate learning and memory, including social recognition – the ability of an animal to recognize another. In ovariectomized female mice, systemic or dorsal hippocampal administration of 17β-estradiol (E2) facilitates short-term social recognition memory within 40 min. Within the same timeframe, E2 increases dendritic spine density in CA1 dorsal hippocampal neurons of behavioural task-naïve mice and in hippocampal sections. Mechanisms underlying these effects remain unclear. Estrogens rapidly modulate actin cytoskeletal dynamics through actin polymerization and the translation of key synaptic proteins. We first determined doses of actin polymerization inhibitor latrunculin A (LAT) and protein synthesis inhibitor anisomycin (ANI) that would block short-term social recognition memory when infused into the dorsal hippocampus of ovariectomized female mice 15 min prior to testing. The highest doses that did not block social recognition prevented the facilitating effects of E2, whereas DNA transcription inhibitor, actinomycin D, could not block social recognition. As task performance may interfere with E2-facilitated increases in dendritic spine density, dendritic spine density and length were examined in task-performing and task-naïve mice. E2 increased dendritic spine density 15 but not 40 min following treatment, regardless of whether the animal had performed the social recognition task. This effect was blocked by LAT, but not ANI. Thus, both actin polymerization and protein synthesis are necessary for E2 to rapidly facilitate social recognition, whereas actin polymerization, but not protein synthesis, is required for the rapid increase in dendritic spine density brought on by E2.