N-acetylcysteine supplementation improves endocrine-metabolism profiles and ovulation induction efficacy in polycystic ovary syndrome.

BACKGROUND: Polycystic ovary syndrome (PCOS) affects 6-20% of women worldwide, with insulin resistance and hyperinsulinemia occurring in 50-70% of patients. Hyperinsulinemia exacerbates oxidative stress, contributing to PCOS pathogenesis. N-acetylcysteine (NAC) is an antioxidant and insulin sensitizer that shows promise as a therapeutic for PCOS. Our current study aimed to investigate the effects of NAC supplementation on endocrine-metabolic parameters in PCOS mice and its effect on ovulation induction (OI) efficacy in women with PCOS. METHODS: Female C57BL/6 mice were orally administered letrozole (LE) to induce PCOS and then randomly divided into groups receiving daily oral administration of 160 mg/kg NAC (PCOS + NAC group), 200 mg/kg metformin (PCOS + Met group), or 0.5% carboxymethyl cellulose (drug solvent) (pure PCOS group) for 12 days. Healthy female mice served as pure controls. Estrous cycles were monitored during the intervention. Metabolic and hormone levels, ovarian phenotypes, antioxidant activity in ovarian tissues, and oxidative stress levels in oocytes were assessed post-intervention. Furthermore, a pragmatic, randomized, controlled clinical study was conducted with 230 PCOS women, randomly assigned to the NAC group (1.8 g/day oral NAC, n = 115) or the control group (n = 115). Patients in both groups underwent ≤ 3 cycles of OI with sequential LE and urinary follicle-stimulating hormone (uFSH). Cycle characteristics and pregnancy outcomes were compared between groups. RESULTS: Similar to metformin, NAC supplementation significantly improved the estrous cycles and ovarian phenotypes of PCOS mice; reduced the LH concentration, LH/FSH ratio, and T level; and increased glucose clearance and insulin sensitivity. Notably, NAC significantly reduced oocyte ROS levels and increased the mitochondrial membrane potential in PCOS mice. Additionally, NAC significantly enhanced enzymatic and nonenzymatic antioxidant activities in PCOS mouse ovaries, whereas metformin had no such effect. In the clinical trial, compared to women in the control group, women receiving NAC had significantly lower average uFSH dosage and duration (p < 0.005) and significantly greater clinical pregnancy rates per OI cycle and cumulative clinical pregnancy rates per patient (p < 0.005). CONCLUSION: NAC supplementation improved endocrine-metabolic parameters in PCOS mice and significantly enhanced OI efficacy with sequential LE and uFSH in women with PCOS. Therefore, NAC could be a valuable adjuvant in OI for women with PCOS.

Neoadjuvant letrozole and palbociclib in patients with HR-positive/HER2-negative early breast cancer and Oncotype DX Recurrence Score ≥18: DxCARTES study.

BACKGROUND: The effect of the addition of cyclin-dependent kinases 4 and 6 inhibitors to endocrine therapy in terms of molecular downstaging remains undetermined. Switching from a high-risk to a low risk Recurrence Score (RS) group could provide useful information to identify patients who might not require chemotherapy. The purpose of this study was to assess the biological and clinical activity of letrozole plus palbociclib as neoadjuvant treatment for patients with hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative early breast cancer with an initial Oncotype DX RS ≥18. PATIENTS AND METHODS: Participants were women aged ≥18 years with HR-positive/HER2-negative, Ki67 ≥ 20%, stage II-IIIB early breast cancer with a baseline RS ≥18. Eligible patients with a pretreatment RS 18-25 (cohort A) and 26-100 (cohort B) received six 28-day cycles of letrozole (2.5 mg per day; plus goserelin if pre- or perimenopausal) plus palbociclib (125 mg per day; 3/1 schedule) before surgery. The primary endpoint for both cohorts was the proportion of patients who achieved an RS ≤25 at surgery or a pathological complete response (pCR). RESULTS: A total of 67 patients were enrolled, among which 65 were assessable for the primary endpoint (32 patients in cohort A and 33 in cohort B). At surgery, 22 (68.8%) patients in cohort A and 18 (54.5%) patients in cohort B had an RS ≤25 or a pCR [only 1 (3.0%) patient in cohort B], meeting the primary endpoint in cohort B (P < 0.01), but not in cohort A (P = 0.98). No new safety signals were identified. CONCLUSIONS: The efficacy of neoadjuvant treatment with letrozole plus palbociclib does not seem to depend on pretreatment RS for patients with RS ≥18. However, around half of patients with HR-positive/HER2-negative early breast cancer with an RS 26-100 at baseline achieved molecular downstaging with this regimen.

Increasing membrane polyunsaturated fatty acids sensitizes non-small cell lung cancer to anti-PD-1/PD-L1 immunotherapy.

Immune checkpoints inhibitors (ICIs) as anti-PD-1/anti-PD-L1 have been approved as first-line treatment in patients with non-small cell lung cancer (NSCLC), but only 25 % of patients achieve durable response. We previously unveiled that estrogen receptor α transcriptionally up-regulates PD-L1 and aromatase inhibitors such as letrozole increase the efficacy of pembrolizumab. Here we investigated if letrozole may have additional immune-sensitizing mechanisms. We found that higher the level of PD-L1 in NSCLC, higher the activation of SREBP1c that transcriptionally increases fatty acid synthase and stearoyl-CoA desaturase enzymes, increasing the amount of polyunsaturated fatty acids (PUFAs). Letrozole further up-regulated SREBP1c-mediated transcription of lipogenic genes, and increased the amount of PUFAs, thereby leading to greater membrane fluidity and reduced binding between PD-L1 and PD-1. The same effects were observed upon supplementation with ω3-PUFA docosahexaenoic acid (DHA) that enhanced the efficacy of pembrolizumab in humanized NSCLC immune-xenografts. We suggest that PUFA enrichment in membrane phospholipids improves the efficacy of ICIs. We propose to repurpose letrozole or DHA as new immune-sensitizing agents in NSCLC.

Acetate attenuates hypothalamic pyroptosis in experimentally induced polycystic ovarian syndrome.

This study hypothesized that SCFA, acetate impacts positively on hypothalamic pyroptosis and its related abnormalities in experimentally induced PCOS rat model, possibly through NrF2/HIF1-α modulation. Eight-week-old female Wister rats were divided into groups (n = 5), namely control, PCOS, acetate and PCOS + acetate groups. Induction of PCOS was performed by administering 1 mg/kg body weight of letrozole for 21 days. After PCOS confirmation, the animals were treated with 200 mg/kg of acetate for 6 weeks. Rats with PCOS were characterized with insulin resistance, leptin resistance, increased plasma testosterone as well as degenerated ovarian follicles. There was also a significant increase in hypothalamic triglyceride level, triglyceride-glucose index, inflammatory biomarkers (SDF-1 and NF-kB) and caspase-6 as well as plasma LH and triglyceride. A decrease was observed in plasma adiponectin, GnRH, FSH, and hypothalamic GABA with severe inflammasome expression in PCOS rats. These were accompanied by decreased level of NrF2/HIF1-α, and the alterations were reversed when treated with acetate. Collectively, the present results suggest the therapeutic impact of acetate on hypothalamic pyroptosis and its related comorbidity in PCOS, a beneficial effect that is accompanied by modulation of NrF2/HIF1-α.

Brown adipose tissue-derived exosomes improve polycystic ovary syndrome in mice via STAT3/GPX4 signaling pathway.

Polycystic ovary syndrome (PCOS) is associated with impaired adipose tissue physiology. Elevated brown adipose tissue (BAT) mass or activity has shown potential in the treatment of PCOS. In this study, we aimed to investigate whether BAT-derived exosomes (BAT-Exos), as potential biomarkers of BAT activity, exert similar benefits as BAT in the treatment of PCOS. PCOS was induced in female C57BL/6J mice orally administered 1 mg/kg of letrozole for 21 days. Subsequently, the animals underwent transplantation with BAT or administered BAT-Exos (200 µg) isolated from young healthy mice via the tail vein; healthy female mice were used as controls. The results indicate that BAT-Exos treatment significantly reduced body weight and improved insulin resistance in PCOS mice. In addition, BAT-Exos improved ovulation function by reversing the acyclicity of the estrous cycle, decreasing circulating luteinizing hormone and testosterone, recovering ovarian performance, and improving oocyte quality, leading to a higher pregnancy rate and litter size. Furthermore, western blotting revealed reduced expression of signal transducer and activator of transcription 3 (STAT3) and increased expression of glutathione peroxidase 4 (GPX4) in the ovaries of mice in the BAT-Exos group. To further explore the role of the STAT3/GPX4 signaling pathway in PCOS mice, we treated the mice with an intraperitoneal injection of 5 mg/kg stattic, a STAT3 inhibitor. Consistent with BAT-Exos treatment, the administration of stattic rescued letrozole-induced PCOS phenotypes. These findings suggest that BAT-Exos treatment might be a potential therapeutic strategy for PCOS and that the STAT3/GPX4 signaling pathway is a critical therapeutic target for PCOS.

Effects of short-term oral letrozole on fresh semen parameters, endocrine balance, and prostate gland dimensions in domestic dogs.

BACKGROUND: Aromatase inhibitors improve male fertility by modifying the hormonal control of spermatogenesis. The present study aimed to investigate the effects of oral administration of letrozole on testosterone and estradiol concentrations and their ratios in blood serum, seminal plasma, prostatic fluid, sperm quality in fresh semen, and prostate gland dimensions. Seven adult male intact mixed-breed dogs were selected. The animals received letrozole (72 µg/kg, PO) daily for four weeks. Blood samplings and semen collections were carried out on days 0 (control), 14 (treatment), 28 (treatment), and 42 (post-treatment). RESULTS: Our results showed that letrozole administration resulted in a 4.3 fold significant increase in serum, seminal plasma, and prostatic fluid testosterone levels after 14 days. This remained high until the end of the study. Serum and prostatic fluid estradiol levels did not change significantly over the study period. However, the seminal plasma estradiol level showed a significant increase on day 14. The estradiol: testosterone ratio was significantly reduced on day 14 in serum, seminal plasma, and prostatic fluid samples. Letrozole significantly improved the ejaculated spermatozoa viability and concentration after 28 days of oral administration. However, the sperm plasma membrane functional integrity and kinematic parameters were not significantly affected by the treatment. Transabdominal ultrasound examination revealed a significant increase in the height, width, and volume of the prostate gland after 28 days of treatment. CONCLUSIONS: According to the present research, oral administration of letrozole for 28 days affects local and systemic sex hormone balance leading to an improvement of the ejaculated canine spermatozoa viability and concentration concurrent with an increase in the prostate gland dimensions.

Granulosa cell insight: unraveling the potential of menstrual blood-derived stem cells and their exosomes on mitochondrial mechanisms in polycystic ovary syndrome (PCOS).

BACKGROUND: Polycystic ovary syndrome (PCOS) presents a significant challenge in women's reproductive health, characterized by disrupted folliculogenesis and ovulatory dysfunction. Central to PCOS pathogenesis are granulosa cells, whose dysfunction contributes to aberrant steroid hormone production and oxidative stress. Mitochondrial dysfunction emerges as a key player, influencing cellular energetics, oxidative stress, and steroidogenesis. This study investigates the therapeutic potential of menstrual blood-derived stem cells (MenSCs) and their exosomes in mitigating mitochondrial dysfunction and oxidative stress in PCOS granulosa cells. METHODS: Using a rat model of PCOS induced by letrozole, granulosa cells were harvested and cultured. MenSCs and their exosomes were employed to assess their effects on mitochondrial biogenesis, oxidative stress, and estrogen production in PCOS granulosa cells. RESULTS: Results showed diminished mitochondrial biogenesis and increased oxidative stress in PCOS granulosa cells, alongside reduced estrogen production. Treatment with MenSCs and their exosomes demonstrated significant improvements in mitochondrial biogenesis, oxidative stress levels, and estrogen production in PCOS granulosa cells. Further analysis showed MenSCs' superior efficacy over exosomes, attributed to their sustained secretion of bioactive factors. Mechanistically, MenSCs and exosomes activated pathways related to mitochondrial biogenesis and antioxidative defense, highlighting their therapeutic potential for PCOS. CONCLUSIONS: This study offers insights into granulosa cells mitochondria's role in PCOS pathogenesis and proposes MenSCs and exosomes as a potential strategy for mitigating mitochondrial dysfunction and oxidative stress in PCOS. Further research is needed to understand underlying mechanisms and validate clinical efficacy, presenting promising avenues for addressing PCOS complexity.

Targeted inhibition of kisspeptin neurons reverses hyperandrogenemia and abnormal hyperactive LH secretion in a preclinical mouse model of polycystic ovary syndrome.

STUDY QUESTION: Do hyperactive kisspeptin neurons contribute to abnormally high LH secretion and downstream hyperandrogenemia in polycystic ovary syndrome (PCOS)-like conditions and can inhibition of kisspeptin neurons rescue such endocrine impairments? SUMMARY ANSWER: Targeted inhibition of endogenous kisspeptin neuron activity in a mouse model of PCOS reduced the abnormally hyperactive LH pulse secretion and hyperandrogenemia to healthy control levels. WHAT IS KNOWN ALREADY: PCOS is a reproductive disorder characterized by hyperandrogenemia, anovulation, and/or polycystic ovaries, along with a hallmark feature of abnormal LH hyper-pulsatility, but the mechanisms underlying the endocrine impairments remain unclear. A chronic letrozole (LET; aromatase inhibitor) mouse model recapitulates PCOS phenotypes, including polycystic ovaries, anovulation, high testosterone, and hyperactive LH pulses. LET PCOS-like females also have increased hypothalamic kisspeptin neuronal activation which may drive their hyperactive LH secretion and hyperandrogenemia, but this has not been tested. STUDY DESIGN, SIZE, DURATION: Transgenic KissCRE+/hM4Di female mice or littermates Cre- controls were treated with placebo, or chronic LET (50 µg/day) to induce a PCOS-like phenotype, followed by acute (once) or chronic (2 weeks) clozapine-N-oxide (CNO) exposure to chemogenetically inhibit kisspeptin cells (n = 6 to 10 mice/group). PARTICIPANTS/MATERIALS, SETTING, METHODS: Key endocrine measures, including in vivo LH pulse secretion patterns and circulating testosterone levels, were assessed before and after selective kisspeptin neuron inhibition and compared between PCOS groups and healthy controls. Alterations in body weights were measured and pituitary and ovarian gene expression was determined by qRT-PCR. MAIN RESULTS AND THE ROLE OF CHANCE: Acute targeted inhibition of kisspeptin neurons in PCOS mice successfully lowered the abnormally hyperactive LH pulse secretion (P < 0.05). Likewise, chronic selective suppression of kisspeptin neuron activity reversed the previously high LH and testosterone levels (P < 0.05) down to healthy control levels and rescued reproductive gene expression (P < 0. 05). LARGE SCALE DATA: N/A. LIMITATIONS, REASONS FOR CAUTION: Ovarian morphology was not assessed in this study. Additionally, mouse models can offer mechanistic insights into neuroendocrine processes in PCOS-like conditions but may not perfectly mirror PCOS in women. WIDER IMPLICATIONS OF THE FINDINGS: These data support the hypothesis that overactive kisspeptin neurons can drive neuroendocrine PCOS-like impairments, and this may occur in PCOS women. Our findings complement recent clinical investigations using NKB receptor antagonists to lower LH in PCOS women and suggest that pharmacological dose-dependent modulation of kisspeptin neuron activity may be a valuable future therapeutic target to clinically treat hyperandrogenism and lower elevated LH in PCOS women. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by NIH grants R01 HD111650, R01 HD090161, R01 HD100580, P50 HD012303, R01 AG078185, and NIH R24 HD102061, and a pilot project award from the British Society for Neuroendocrinology. There are no competing interests.

Ameliorating effects of adropin on letrozole-induced polycystic ovary syndrome via regulating steroidogenesis and the microbiota inflammatory axis in rats.

Growing evidence supports the role of gut microbiota in chronic inflammation, insulin resistance (IR) and sex hormone production in polycystic ovary syndrome (PCOS). Adropin plays a pivotal role in the regulation of glucose and lipid metabolism and is negatively correlated with IR, which affects intestinal microbiota and sex hormones. However, the effect of adropin administration in PCOS has yet to be investigated. The present study aimed to assess the effects of adropin on letrozole (LTZ)-induced PCOS in rats and the potential underlying mechanisms. The experimental groups were normal, adropin, letrozole and LTZ + adropin. At the end of the experiment, adropin significantly ameliorated PCOS, as evidenced by restoring the normal ovarian structure, decreasing the theca cell thickness in antral follicles, as well as serum testosterone and luteinizing hormone levels and luteinizing hormone/follicle-stimulating hormone ratios, at the same time as increasing granulosa cell thickness in antral follicles, oestradiol and follicle-stimulating hormone levels. The ameliorating effect could be attributed to its effect on sex hormone-binding globulin, key steroidogenic genes STAR and CYP11A1, IR, lipid profile, gut microbiota metabolites-brain-ovary axis components (short chain fatty acids, free fatty acid receptor 3 and peptide YY), intestinal permeability marker (zonulin and tight junction protein claudin-1), lipopolysaccharides/Toll-like receptor 4/nuclear factor kappa B inflammatory pathway and oxidative stress makers (malondialdehyde and total antioxidant capacity). In conclusion, adropin has a promising therapeutic effect on PCOS by regulating steroidogenesis, IR, lipid profile, the gut microbiota inflammatory axis and redox homeostasis. KEY POINTS: Adropin treatment reversed endocrine and ovarian morphology disorders in polycystic ovary syndrome (PCOS). Adropin regulated the ovarian steroidogenesis and sex hormone-binding globulin in PCOS. Adropin improved lipid profile and decreased insulin resistance in PCOS. Adropin modulated the components of the gut-brain-ovary axis (short chain fatty acids, free fatty acid receptor 3 and peptide YY) in PCOS. Adropin improved intestinal barrier integrity, suppressed of lipopolysaccharides/Toll-like receptor 4/nuclear factor kappa B signalling pathway and oxidative stress in PCOS.

Cytoarchitectural differences in reproductive organs of some polycystic ovary-like induced animal models.

Polycystic ovary syndrome (PCOS) is the most common gynaecological, endocrine disorder that occurs during reproductive age and is a significant cause of anovulatory infertility. Letrozole is an aromatase inhibitor which negates the action of the aromatase enzyme, which results in the buildup of male hormones (testosterone) in the females, causing hyperandrogenism, which is a hallmark of Polycystic Ovarian Syndrome. Mifepristone (RU486) is a progestin antagonist that acts to arrest the actions of the progesterone hormone, resulting in follicular atresia and anovulation. DHEA is an androgen which was also administered in a bid to cause hyperandrogenism in the rats.This study aimed to evaluate the effects of these hormones on the cytoarchitecture of the ovaries and uterus to assess their various PCOS-like histological features.Animals were grouped mainly into three: Letrozole, Mifepristone and DHEA groups, which were further divided into two subgroups each, administered low and high doses of letrozole orally, Mifepristone and Dehydroepiandosterone (DHEA) subcutaneously. Each of the subgroups also had a comparison control group. Following the completion of administration, the Wistar rats were euthanized, and their ovaries and uterus were collected for histological analysis.Increased proliferation of ovarian follicles was noted in the treated groups compared to control, as well as thickening of the endometrial layer.

Characteristics of the Vasa Gene in Silurus asotus and Its Expression Response to Letrozole Treatment.

The identification and expression of germ cells are important for studying sex-related mechanisms in fish. The vasa gene, encoding an ATP-dependent RNA helicase, is recognized as a molecular marker of germ cells and plays a crucial role in germ cell development. Silurus asotus, an important freshwater economic fish species in China, shows significant sex dimorphism with the female growing faster than the male. However, the molecular mechanisms underlying these sex differences especially involving in the vasa gene in this fish remain poorly understood. In this work, the vasa gene sequence of S. asotus (named as Savasa) was obtained through RT-PCR and rapid amplification of cDNA end (RACE), and its expression in embryos and tissues was analyzed using qRT-PCR and an in situ hybridization method. Letrozole (LT) treatment on the larvae fish was also conducted to investigate its influence on the gene. The results revealed that the open reading frame (ORF) of Savasa was 1989 bp, encoding 662 amino acids. The SaVasa protein contains 10 conserved domains unique to the DEAD-box protein family, showing the highest sequence identity of 95.92% with that of Silurus meridionalis. In embryos, Savasa is highly expressed from the two-cell stage to the blastula stage in early embryos, with a gradually decreasing trend from the gastrula stage to the heart-beating stage. Furthermore, Savasa was initially detected at the end of the cleavage furrow during the two-cell stage, later condensing into four symmetrical cell clusters with embryonic development. At the gastrula stage, Savasa-positive cells increased and began to migrate towards the dorsal side of the embryo. In tissues, Savasa is predominantly expressed in the ovaries, with almost no or lower expression in other detected tissues. Moreover, Savasa was expressed in phase I-V oocytes in the ovaries, as well as in spermatogonia and spermatocytes in the testis, implying a specific expression pattern of germ cells. In addition, LT significantly upregulated the expression of Savasa in a concentration-dependent manner during the key gonadal differentiation period of the fish. Notably, at 120 dph after LT treatment, Savasa expression was the lowest in the testis and ovary of the high concentration group. Collectively, findings from gene structure, protein sequence, phylogenetic analysis, RNA expression patterns, and response to LT suggest that Savasa is maternally inherited with conserved features, serving as a potential marker gene for germ cells in S.asotus, and might participate in LT-induced early embryonic development and gonadal development processes of the fish. This would provide a basis for further research on the application of germ cell markers and the molecular mechanisms of sex differences in S. asotus.

Lasofoxifene as a potential treatment for aromatase inhibitor-resistant ER-positive breast cancer.

BACKGROUND: Breast cancers treated with aromatase inhibitors (AIs) can develop AI resistance, which is often driven by estrogen receptor-alpha (ERα/ESR1) activating mutations, as well as by ER-independent signaling pathways. The breast ER antagonist lasofoxifene, alone or combined with palbociclib, elicited antitumor activities in a xenograft model of ER + metastatic breast cancer (mBC) harboring ESR1 mutations. The current study investigated the activity of LAS in a letrozole-resistant breast tumor model that does not have ESR1 mutations. METHODS: Letrozole-resistant, MCF7 LTLT cells tagged with luciferase-GFP were injected into the mammary duct inguinal glands of NSG mice (MIND model; 6 mice/group). Mice were randomized to vehicle, lasofoxifene ± palbociclib, fulvestrant ± palbociclib, or palbociclib alone 2-3 weeks after cell injections. Tumor growth and metastases were monitored with in vivo and ex vivo luminescence imaging, terminal tumor weight measurements, and histological analysis. The experiment was repeated with the same design and 8-9 mice in each treatment group. RESULTS: Western blot analysis showed that the MCF7 LTLT cells had lower ERα and higher HER2 expressions compared with normal MCF7 cells. Lasofoxifene ± palbociclib, but not fulvestrant, significantly reduced primary tumor growth versus vehicle as assessed by in vivo imaging of tumors at study ends. Percent tumor area in excised mammary glands was significantly lower for lasofoxifene plus palbociclib versus vehicle. Ki67 staining showed decreased overall tumor cell proliferation with lasofoxifene ± palbociclib. The lasofoxifene + palbociclib combination was also associated with significantly fewer bone metastases compared with vehicle. Similar results were observed in the repeat experiment. CONCLUSIONS: In a mouse model of letrozole-resistant breast cancer with no ESR1 mutations, reduced levels of ERα, and overexpression of HER2, lasofoxifene alone or combined with palbociclib inhibited primary tumor growth more effectively than fulvestrant. Lasofoxifene plus palbociclib also reduced bone metastases. These results suggest that lasofoxifene alone or combined with a CDK4/6 inhibitor may offer benefits to patients who have ER-low and HER2-positive, AI-resistant breast cancer, independent of ESR1 mutations.

Ameliorative potential of rosmarinic acid in a rat model of polycystic ovary syndrome: Targeting MCP-1 and VEGF: A histological, immunohistochemical, and biochemical study.

Polycystic ovary syndrome (PCOS) is a multidisciplinary endocrinopathy that affects women of reproductive age. It is characterized by menstrual complications, hyperandrogenism, insulin resistance, and cardiovascular issues. The current research investigated the efficacy of rosmarinic acid in letrozole-induced PCOS in adult female rats as well as the potential underlying molecular mechanisms. Forty female rats were divided into the control group, the rosmarinic acid group (50 mg/kg per orally, po) for 21 days, PCOS group; PCOS was induced by administration of letrozole (1 mg/kg po) for 21 days, and rosmarinic acid-PCOS group, received rosmarinic acid after PCOS induction. PCOS resulted in a marked elevation in both serum luteinizing hormone (LH) and testosterone levels and LH/follicle-stimulating hormone ratio with a marked reduction in serum estradiol and progesterone levels. A marked rise in tumor necrosis factor-α (TNF-α), interleukin-1ß, monocyte chemotactic protein-1, and vascular endothelial growth factor (messenger RNA) in the ovarian tissue was reported. The histological analysis displayed multiple cystic follicles in the ovarian cortex with markedly thin granulosa cell layer, vacuolated granulosa and theca cell layers, and desquamated granulosa cells. Upregulation in the immune expression of TNF-α and caspase-3 was demonstrated in the ovarian cortex. Interestingly, rosmarinic acid ameliorated the biochemical and histopathological changes. In conclusion, rosmarinic acid ameliorates letrozole-induced PCOS through its anti-inflammatory and antiangiogenesis effects.

Hyperglycemia Inhibits Hepatic SHBG Synthesis Through the NGBR-AMPK-HNF4 Pathway in Rats with Polycystic Ovary Syndrome Induced by Letrozole in Combination with a High-Fat Diet.

SCOPE: Polycystic ovary syndrome (PCOS) is closely related to non-alcoholic fatty liver disease (NAFLD), and sex hormone-binding globulin (SHBG) is a glycoprotein produced by the liver. Hepatic lipogenesis inhibits hepatic SHBG synthesis, which leads to hyperandrogenemia and ovarian dysfunction in PCOS. Therefore, this study aims to characterize the mechanism whereby liver lipogenesis inhibits SHBG synthesis. METHODS AND RESULTS: This study establishes a rat model of PCOS complicated by NAFLD using a high-fat diet in combination with letrozole and performs transcriptomic analysis of the liver. Transcriptomic analysis of the liver shows that the expression of neurite growth inhibitor-B receptor (NgBR), hepatocyte nuclear factor 4α (HNF4α), and SHBG is low. Meantime, HepG2 cells are treated with palmitic acid (PA) to model NAFLD in vitro, which causes decreases in the expression of NgBR, HNF4α, and SHBG. However, the expression of HNF4α and SHBG is restored by treatment with the AMP-activated protein kinase (AMPK) agonist AICAR. CONCLUSIONS: NgBR regulates the expression of HNF4α by activating the AMPK signaling pathway, thereby affecting the synthesis of SHBG in the liver. Further mechanistic studies regarding the effect of liver fat on NGBR expression are warranted.

The role of neuroestrogens in the estrogen-induced gonadotropin surge in male monkeys.

Neuroestrogens locally synthesized in the brain are known to play a role in sexual behaviors. However, the question of whether neuroestrogens are involved in the regulation of the gonadotropin-releasing hormone (GnRH) release is just emerging. Because previous studies in this lab indicate that neuroestradiol is also important for the pulsatile release as well as the surge release of GnRH in female rhesus monkeys, in the present study, we examined whether neuroestradiol plays a role in the estrogen-induced LH surge in orchidectomized (ORX) male rhesus monkeys. Unlike in rodents, it is known that a high dose of estrogen treatment can result in the LH surge in ORX male rhesus monkeys. Results that the administration of the aromatase inhibitor, letrozole, failed to attenuate the estrogen-induced LH surge, suggest that unlike in ovariectomized females, neuroestrogens do not play a role in the LH surge experimentally induced by the exogenous estrogen treatment in ORX male monkeys.

Fisetin mitigates letrozole-induced polycystic ovarian syndrome in rats: crosstalk of AMPK/PI3K/AKT-mediated-Nrf2 antioxidant defense mechanism and the inflammasome NLRP3/NF-κB P65/IL-1ß signaling pathways.

Polycystic ovarian syndrome (PCOS) is a highly prevalent condition affecting reproductive-aged women, causing insulin resistance, hyperandrogenism, weight gain, and menstrual problems. The present study intended to investigate the potential role of fisetin (FT) in letrozole (LZ)-induced PCOS in adult female rats and the possible mechanism underlying its action. PCOS was induced by oral administration of LZ (1 mg/kg) for 21 days. Treated rats received FT (1.25 or 2.5 mg/kg) orally once daily for 14 consecutive days. Following the experimental duration, blood samples and ovary tissues were isolated and preserved for biochemical and histopathological examinations. The results revealed that LZ-induced PCOS led to significant abnormalities in sex hormones and metabolic parameters. Additionally, it initiated an inflammatory cascade, evidenced by activation of the NF-κB p65/IL-1ß and AMPK/PI3K/AKT pathways, alongside downregulation of Nrf2 ovarian gene expression and NLRP3 inflammasome activity, which enhanced the production of proinflammatory cytokines. FT demonstrated its beneficial impacts by restoring hormonal disturbance and reversing the imbalanced metabolic parameters. Moreover, FT increased the mRNA of ovarian Nrf2 levels and suppressed the up-regulated inflammatory IL-1ß/NF-κB p65 signaling pathway, consequently alleviating the elevated levels of ovarian NLRP3. The histopathological examination also confirmed that FT has a beneficial effect in ameliorating PCOS, consistent with the aforementioned parameters. Finally, the present results demonstrated that FT ameliorates LZ-induced PCOS through the intricate interplay between the AMPK/PI3K/AKT-mediated Nrf2 antioxidant defense mechanism and the regulation of the inflammasome NLRP3/NF-κB p65/IL-1ß signaling pathways.

Apelin receptor modulation mitigates letrozole-induced polycystic ovarian pathogenesis in mice.

AIMS: Polycystic ovarian syndrome (PCOS) is one of the most common (about 5-20%) reproductive disorders in women of reproductive age; it is characterized by polycystic ovaries, hyperandrogenism, and oligo/ anovulation. The levels and expression of ovarian adipokines are deregulated in the PCOS. Apelin is an adipokine that acts through its receptor (APJ) and is known to express in the various tissues including the ovary. It has also been suggested that apelin and APJ could be targeted as therapeutic adjuncts for the management of PCOS. However, no study has been conducted on the management of PCOS by targeting the apelin system. Thus, we aimed to evaluate its impact on combating PCOS-associated ovarian pathogenesis. METHODS: The current work employed a letrozole-induced-hyperandrogenism PCOS-like mice model to investigate the effects of apelin13 and APJ, antagonist ML221. The PCOS model was induced by oral administration of letrozole (1 mg/kg) for 21 days. A total of four experimental groups were made, control, PCOS control, PCOS + aplein13, and PCOS + ML221. The treatment of apelin13 and ML221 was given from day 22 for two weeks. KEY FINDINGS: The letrozole-induced PCOS-like features such as hyperandrogenism, cystic follicle, decreased corpus luteum, elevated levels of LH/FSH ratio, and up-regulation of ovarian AR expression were ameliorated by apelin13 and ML221 treatment. However, the PCOS-augmented oxidative stress and apoptosis were suppressed by apelin 13 treatments only. ML221 treatment still showed elevated oxidative stress and stimulated apoptosis as reflected by decreased antioxidant enzymes and increased active caspase3 and Bax expression. The expression of ERs was elevated in all groups except control. Furthermore, the PCOS model showed elevated expression of APJ and apelin13 treatment down-regulated its own receptor. Overall, observing the ovarian histology, corpus luteum formation, and decreased androgen levels by both apelin13 and ML221 showed ameliorative effects on the cystic ovary. SIGNIFICANCE: Despite the similar morphological observation of ovarian histology, apelin13 and ML221 exhibited opposite effects on oxidative stress and apoptosis. Therefore, apelin13 (which down-regulates APJ) and ML221 (an APJ antagonist) may have suppressed APJ signalling, which would account for our findings on the mitigation of polycystic ovarian syndrome. In conclusion, both apelin13 and ML221 mediated mitigation have different mechanisms, which need further investigation.

Estrogen stimulates fetal vascular endothelial growth factor expression and microvascularization.

We recently showed that the ratio of capillaries to myofibers in skeletal muscle, which accounts for 80% of insulin-directed glucose uptake and metabolism, was reduced in baboon fetuses in which estrogen was suppressed by maternal letrozole administration. Since vascular endothelial growth factor (VEGF) promotes angiogenesis, the present study determined the impact of estrogen deprivation on fetal skeletal muscle VEGF expression, capillary development, and long-term vascular and metabolic function in 4- to 8-year-old adult offspring. Maternal baboons were untreated or treated with letrozole or letrozole plus estradiol on days 100-164 of gestation (term = 184 days). Skeletal muscle VEGF protein expression was suppressed by 45% (P < 0.05) and correlated (P = 0.01) with a 47% reduction (P < 0.05) in the number of capillaries per myofiber area in fetuses of baboons in which serum estradiol levels were suppressed 95% (P < 0.01) by letrozole administration. The reduction in fetal skeletal muscle microvascularization was associated with a 52% decline (P = 0.02) in acetylcholine-induced brachial artery dilation and a 23% increase (P = 0.01) in mean arterial blood pressure in adult progeny of letrozole-treated baboons, which was restored to normal by letrozole plus estradiol. The present study indicates that estrogen upregulates skeletal muscle VEGF expression and systemic microvessel development within the fetus as an essential programming event critical for ontogenesis of systemic vascular function and insulin sensitivity/glucose homeostasis after birth in primate offspring.

Sodium oligomannate's amelioration of reproductive and metabolic phenotypes in a letrozole-induced PCOS-like mouse model depends on the gut microbiome†.

It has been well established that there is a connection between polycystic ovary syndrome pathology and gut microbiome dysbiosis. A marine-derived oligosaccharide, GV-971, has been reported to alter gut microbiota and alleviate Aß amyloidosis. In this study, the effects of GV-971 on polycystic ovary syndrome-like mice were explored. Mice were randomly assigned into four groups: control, letrozole, letrozole + GV-971, and control + GV-971. Glucose metabolism in polycystic ovary syndrome-like mice was ameliorated by GV-971, while the reproductive endocrine disorder of polycystic ovary syndrome-like mice was partially reversed. The messenger ribonucleic acid levels of steroidogenic enzymes in ovaries of polycystic ovary syndrome-like mice were improved. GV-971 restored the fertility of polycystic ovary syndrome-like mice and significantly increase the number of litters. Furthermore, GV-971 treatment effectively mitigated abnormal bile acid metabolism. Notably, after GV-971 intervention, gut microbiota alpha-diversity was considerably raised and the relative abundance of Firmicutes was reduced. In conclusion, the hyperinsulinemia and hyperandrogenemia of polycystic ovary syndrome-like mice were alleviated by GV-971 intervention, which was associated with mitigating bile acid metabolism and modulating gut microbiota.

The effect of adipose-derived mesenchymal stem cell transplantation on ovarian mitochondrial dysfunction in letrozole-induced polycystic ovary syndrome in rats: the role of PI3K-AKT signaling pathway.

OBJECTIVE: The present study aimed to elucidate how mesenchymal stem cells (MSCs) application could efficiently attenuate pathological changes of letrozole-induced poly cystic ovary syndrome (PCOS) by modulating mitochondrial dynamic via PI3K-AKT pathway. METHODS: Thirty-two female rats were randomly divided into four experimental groups: Sham, PCOS, PCOS + MSCs, and PCOS + MSCs + LY294002. The Sham group received 0.5% w/v carboxymethyl cellulose (CMC); the PCOS group received letrozole (1 mg/kg, daily) in 0.5% CMC for 21 days. Animals in the PCOS + MSCs group received 1 × 106 MSCs/rat (i.p,) on the 22th day of the study. In the PCOS + MSCs + LY294002 group, rats received LY294002 (PI3K-AKT inhibitor) 40 min before MSC transplantation. Mitochondrial dynamic gene expression, mitochondrial membrane potential (MMP), citrate synthase (CS) activity, oxidative stress, inflammation, ovarian histological parameters, serum hormone levels, homeostatic model assessment for insulin resistance (HOMA-IR), insulin and glucose concentrations, p-PI3K and p-AKT protein levels were evaluated at the end of the experiment. RESULTS: PCOS rats showed a significant disruption of mitochondrial dynamics and histological changes, lower MMP, CS, ovary super oxide dismutase (SOD) and estrogen level. They also had a notable rise in insulin and glucose concentrations, HOMA-IR, testosterone level, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) levels, ovarian malondialdehyde (MDA) content as well as a notable decrease in p-PI3K and p-AKT protein levels compared to the Sham group. In the PCOS + MSCs group, the transplantation of MSCs could improve the above parameters. Administration of LY294002 (PI3K-AKT pathway inhibitor) deteriorated mitochondrial dynamic markers, oxidative stress status, inflammation markers, hormonal levels, glucose, and insulin levels and follicular development compared to the PCOS + MSCs group. CONCLUSIONS: This study demonstrated that the protective effects of MSC transplantation in regulating mitochondrial dynamics, promoting mitochondrial biogenesis, competing with redox status and inflammation response were mainly mediated through the PI3K-AKT pathway in the PCOS model.