Reproductive Hormone Secretion Research Articles

RF34 | PMON222 Reproductive Hormone Secretion is Increased by Intranasal Kisspeptin in Humans

Abstract Background Kisspeptin is a critical activator of hypothalamic gonadotrophin releasing hormone (GnRH) neurons and has significant potential to treat common reproductive disorders. To date, kisspeptin has solely been administered to humans via the intravenous or subcutaneous routes, however intranasal administration could offer a novel non-invasive delivery route, which is preferred by patients. We therefore sought to determine the effects of intranasal kisspeptin on reproductive hormone release in humans for the first time. Methods Randomised, double-blinded, placebo-controlled, cross-over study in 12 healthy men (mean±SEM age 28.3±1.7 yrs; BMI 24.5±0.7 kg/m2). After monitored self-administration of intranasal kisspeptin-54 (3.2, 6.4, 12.8 and 25.6 nmol/kg) or 0.9% saline, serum reproductive hormone levels were measured every 15 minutes for four hours. Subsequently, four women (mean age 29.8±3.7 yrs; BMI 21.2±1.1 kg/m2) with hypothalamic amenorrhoea (HA) attended for the same protocol comparing intranasal kisspeptin-54 (12.8 nmol/kg) and 0.9% saline. Mean ±SEM was presented unless otherwise stated. Time profiles of hormone levels during the four-hour study were compared using two-way ANOVA with Bonferroni's multiple comparison test. Multiple means were compared using one-way ANOVA with Bonferroni's multiple comparison test. Results In healthy men, intranasal kisspeptin dose-dependently increased mean luteinising hormone (LH) levels at doses between 3.2-12.8 nmol/kg (p=0.008 and <0.0001 for 6.4 and 12.8 nmol/kg vs saline, respectively), with the maximal rises occurring at 30-45 minutes post-administration. Correspondingly, the area under the curve (AUC) for the LH change was significantly elevated following all doses of kisspeptin compared to saline (saline: -25.4±70.5 h.IU/L; 3.2 nmol/kg: 172.2±64.2 h.IU/L [p=0.03]; 6.4 nmol/kg: 300.2±79.2 h.IU/L [p=0.002]; 12.8 nmol/kg: 595.7±98.3 h.IU/L [p=0.001]; 25.6 nmol/kg: 549.0±108.6 h.IU/L [p<0.0001]). Follicle stimulating hormone (FSH) levels followed a similar trajectory to LH in response to intranasal kisspeptin. Moreover, kisspeptin at 12.8 nmol/kg increased serum testosterone from 120 minutes onwards (p=0.02), with a maximal change from baseline of 4.9±0.7 nmol/L (p=0.03). In women with HA, intranasal kisspeptin increased mean LH (p=0.002 vs saline), with the peak levels occurring at 30-45 minutes post-administration. The AUC for the LH change was 508.4±77.5 h.IU/L (p=0.02 vs saline AUC for LH). The maximal LH change from baseline was 4.1±0.9 IU/L compared to 0.2±0.4 IU/L for saline (p=0.03). Intranasal kisspeptin increased mean FSH (p=0.01 vs saline). No significant changes in downstream serum oestradiol or progesterone were observed during the acute four-hour study. Conclusion We report the first investigation of the effects of intranasal kisspeptin delivery on reproductive hormone release in humans. Our results demonstrate that intranasal kisspeptin robustly and dose-dependently stimulates reproductive hormone release in healthy men and crucially in a patient-group of women with hypogonadism. Given the ongoing development of kisspeptin therapeutics, intranasal kisspeptin therefore offers a novel, safe, effective and non-invasive route of administration for the management of reproductive disorders. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 12:36 p.m. - 12:41 p.m.

Invited review: Translating kisspeptin and neurokinin B biology into new therapies for reproductive health.

The reproductive neuropeptide kisspeptin has emerged as the master regulator of mammalian reproduction due to its key roles in the initiation of puberty and the control of fertility. Alongside the tachykinin neurokinin B and the endogenous opioid dynorphin, these peptides are central to the hormonal control of reproduction. Building on the expanding body of experimental animal models, interest has flourished with human studies revealing that kisspeptin administration stimulates physiological reproductive hormone secretion in both healthy men and women, as well as patients with common reproductive disorders. In addition, emerging therapeutic roles based on neurokinin B for the management of menopausal flushing, endometriosis and uterine fibroids are increasingly recognised. In this review, we focus on kisspeptin and neurokinin B and their potential application as novel clinical strategies for the management of reproductive disorders.

HSP90AA1 promotes viability and lactate production but inhibits hormone secretion of porcine immature Sertoli cells

Heat shock protein 90 (HSP90), as a molecular chaperone, regulates hundreds of protein clients under both physiological and stress conditions in eukaryotic cells. However, the functional role of HSP90 in mammalian male reproduction remains largely unknown. Here, we aimed to investigate the function and effect of HSP90AA1 on the basic and reproductive function of pig immature Sertoli cells (iSCs). We first confirmed that the transfection of pBI-CMV3-HSP90AA1 vector into porcine iSCs for 24 h significantly increased mRNA and protein levels of HSP90AA. Moreover, HSP90AA1 over-expression significantly increased cell viability and the PLK2 mRNA abundance, promoted lactate production via elevating the LDHA activity, and inhibited the secretion of anti-Mullerian hormone and estradiol. In comparison, HSP90AA inhibition by allylamino-17-demethoxygeldanamycin (17-AAG) (2 μM) treatment of pig iSCs for 36 h had a totally contrasting effect, i.e. significantly reduced cell viability, promoted cell apoptosis via modulating expression of genes related to cell cycle and apoptosis (CCNB1, CCN1, PLK2, PTMA, YBX3 and CASP3), suppressed lactate production via dropping LDHA activity, but increased the secretion of anti-Mullerian hormone and estradiol. Taken together, our findings demonstrated that HSP90AA1 could regulate positively cell viability and lactate production, but negatively the secretion of reproductive hormones (anti-Mullerian hormone and estradiol). However, the detailed molecular mechanism of HSP90AA1 remains to be investigated.

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

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

A Simulation Analysis and Screening of Deleterious Nonsynonymous Single Nucleotide Polymorphisms (nsSNPs) in Sheep LEP Gene

Leptin is a polypeptide hormone produced in the adipose tissue and governs many processes in the body. Recently, polymorphisms in the LEP gene revealed a significant change in body weight regulation, energy balance, food intake, and reproductive hormone secretion. This study considers its crucial role in the regulation of the economically important traits of sheep. Several computational tools, including SIFT, Predict SNP2, SNAP2, and PROVEAN, have been used to screen out the deleterious nsSNPs. Following the screening of 11 nsSNPs in the sheep genome, 5 nsSNPs, T86M (C → T), D98N (G → A), N136T (A → C), R142Q (G → A), and P157Q (C → A), were predicted to have a significant deleterious effect on the LEP protein function, leading to phenotypic difference. The analysis of proteins' stability change due to amino acid substitution using the I-stable, SDM, and DynaMut consistently confirmed that three nsSNPs (T86M (C → T), D98N (G → A), and P157Q (C → A)) increased protein stability. It is suggested that these three nsSNPs may enhance the evolvability of LEP protein, which is vital for the evolutionary adaptation of sheep. Our findings demonstrate that the five nsSNPs reported in this study might be responsible for sheep's structural and functional modifications of LEP protein. This is the first comprehensive report on the sheep LEP gene. It narrow downs the candidate nsSNPs for in vitro experiments to facilitate the development of reliable molecular markers for associated traits.

Proteomic changes induced by ascorbic acid treatment on porcine immature Sertoli cells

Somatic Sertoli cells constitute the microenvironment and produce essential substances, to support male germ cell development and maturation in testis. We previously found that ascorbic acid treatment of porcine immature Sertoli cells enhances its proliferation and secretion of reproductive hormones and metabolites, and reprograms the global transcriptome. Proteomics is a powerful tool to systematically profile the underlying protein changes. Here, by employing the TMT-based quantitative proteomics method, we identified 96 and 64 significantly up- and down-regulated proteins in porcine immature Sertoli cells treated by ascorbic acid, respectively. Gene enrichment (GO and KEGG) and protein-protein interaction analyses revealed important molecular pathways (dioxygenase activity, sterol biosynthetic process, PI3K-Akt, negative regulation of peptide hormone secretion, extracellular matrix etc.). Further validation of three proteins, HMGCS1 (cholesterol synthesis), P4HA1 (glycolysis) and KDM5A (demethylation of histone 3 at lysine 4), confirmed their significant differential abundance, respectively. Taken together, our findings show that ascorbic acid can alter multiple important protein molecules and related signaling pathways, which could explain partially phenotypic changes (proliferation, apoptosis, nucleic acid methylation, lactate and reproductive hormone secretion) of porcine immature Sertoli cells as induced by ascorbic acid.

Effect of Sodium Fluoride on Reproductive Function Through Regulating Reproductive Hormone Level and Circulating SIRT1 in Female Rats.

Fluorosis causes female reproductive dysfunction with reduced fertility without established pathogenesis. To clarify the mechanism, Sprague-Dawley female rats were selected with drinking water containing 0, 50 (low), 100 (moderate), and 150mg/L (high) sodium fluoride (NaF) for a short (2months), medium (4months), and long term (6months). The water consumption and body weight of female rats were recorded daily. The effect of NaF on the estrous cycle was examined by vaginal smears and recorded in different term treatments. Female and male rats were mated in a 2:1 ratio for 1week at 2-, 4-, and 6-month treatment time for mating performance and fertility rate. Selected female rats were executed for tissue and blood collection at different treatment terms. Twenty-four-hour urine sample from each female rat was collected using the metabolic cage. The levels of steroid hormones and silent information regulator 2 homolog 1 (SIRT1) in serum were measured by appropriate ELISA kits. Body weight of the high NaF group was significantly less during short-term treatment than that of other treatment groups or control group. Urinary fluoride concentration was increased linearly with treatment time. Treatment of NaF significantly decreased steroid hormone level while increased SIRT1 level in the serum. In addition, NaF treatment significantly decreased pregnancy rate. It is concluded that NaF inhibits the secretion of hormone and estradiol (E2) release from the ovary, thereby reducing the rate of pregnant. SIRT1 may be involved in this NaF-induced reproductive dysfunction in female rats through regulating reproductive hormone, FSH, and LH secretion.

Intranasal kisspeptin administration stimulates reproductive hormone secretion in healthy volunteers and patients with hypogonadism

Intranasal kisspeptin administration stimulates reproductive hormone secretion in healthy volunteers and patients with hypogonadism

The effect of saffron and its constituent, crocin, on anterior pituitary-gonadal axis during pregnancy in the rat: A time-course study

Saffron is traditionally used in some developing countries for abortion. This study was aimed to investigate the effects of saffron aqueous extract and crocin, as one of its constituents, on the secretion of reproductive hormones in pregnant rats. The alteration of reproductive hormones was assayed in the early, middle, and late stages of pregnancy following the administration of different doses of saffron aqueous extract and crocin. Compared to the control group of each stage of pregnancy, the administration of an aqueous extract of saffron reduced estradiol levels in the early and late stages of pregnancy. A high dose of saffron extract in the middle and late stages of pregnancy and crocin in the late stages of pregnancy increased FSH serum levels. Saffron extract in the early stages and crocin in the late stages of pregnancy increase LH levels in a dose-dependent manner. The saffron extract reduces serum progesterone in all three stages of pregnancy. The current study indicated that the abortion effect of saffron is commonly exerted in the early and late stages of pregnancy. In addition, crocin has fewer effects on pregnancy than saffron and can only affect pregnant rats at high doses in the late stages of pregnancy.

A New Perspective on Thyroid Hormones: Crosstalk with Reproductive Hormones in Females.

Accumulating evidence has shown that thyroid hormones (THs) are vital for female reproductive system homeostasis. THs regulate the reproductive functions through thyroid hormone receptors (THRs)-mediated genomic- and integrin-receptor-associated nongenomic mechanisms, depending on TH ligand status and DNA level, as well as transcription and extra-nuclear signaling transduction activities. These processes involve the binding of THs to intracellular THRs and steroid hormone receptors or membrane receptors and the recruitment of hormone-response elements. In addition, THs and other reproductive hormones can activate common signaling pathways due to their structural similarity and shared DNA consensus sequences among thyroid, peptide, and protein hormones and their receptors, thus constituting a complex and reciprocal interaction network. Moreover, THs not only indirectly affect the synthesis, secretion, and action of reproductive hormones, but are also regulated by these hormones at the same time. This crosstalk may be one of the pivotal factors regulating female reproductive behavior and hormone-related diseases, including tumors. Elucidating the interaction mechanism among the aforementioned hormones will contribute to apprehending the etiology of female reproductive diseases, shedding new light on the treatment of gynecological disorders.

Comprehensive analysis of differences in N6-methyladenosine RNA methylomes in the ratadenohypophysis after GnRH treatment.

N6-methyladenosine is considered to be the most common and abundant internal chemical modification among the more than 150 identified chemical RNA modifications. It is involved in most biological processes and actively participates in the regulation of animal reproduction. However, the potential function of m6 A in the pituitaries of mammals is not yet clear. It is also unknown whether m6 A is involved in the secretion and regulation of FSH by GnRH, which in turn affects mammalian reproduction. In this study, rats were treated with gonadorelin to simulate physiological GnRH-mediated regulation of FSH synthesis and secretion, and m6 A-seq was used to analyze the differential m6 A modification of the rat pituitary after gonadorelin treatment. A whole-transcriptome map of m6 A in the rat pituitary gland before and after gonadorelin treatment was successfully created. A total of 6413 differential peaks were identified, of which 3764m6 A peaks were upregulated and 2649m6 A peaks were downregulated. Among the 709 differentially expressed genes, 250genes were discovered with differential methylation modifications. Intriguingly, the altered m6 A peaks within mRNAs were enriched in steroid biosynthetic processes and responses to cAMP. The results of the study will lay a foundation for further exploration of the potential role of m6 A modification in the regulation of reproductive hormone secretion and provide a theoretical basis for the application of GnRH analogs in mammalian artificial reproduction.

Targeting GNAQ in hypothalamic nerve cells to regulate seasonal estrus in sheep

Kazakh sheep are typical seasonal estrus animals. Their reproductive system regulation mainly involves the complex regulation of the hypothalamic–pituitary–gonadal axis (HPGA), which is also closely related to reproductive hormone secretion. Gonadotropin-releasing hormone (GnRH), synthesized and secreted by the hypothalamus, is the key to controlling sheep reproductive activity. We studied how GNAQ (G protein subunit alpha q) regulates estrus in sheep by controlling GnRH expression and secretion. We used hypothalamic nerve cells as the research model. GNAQ overexpression and RNA interference vectors were constructed and transfected into the hypothalamic nerve cells of fetal Kazakh sheep. qPCR, western blotting, and enzyme-linked immunosorbent assay were used to detect GNAQ gene expression in Kazakh ewe tissues and analyze its regulatory effect on GnRH expression in the hypothalamic nerve cells. The fetal sheep hypothalamic nerve cells were successfully isolated and cultured. qPCR and cell immunofluorescence showed that the purity of positive cells was >95%. The tissue expression profile showed that there were different degrees of GNAQ gene expression in the Kazakh ewe tissue. Expression levels were relatively higher in the hypothalamus, pituitary, brain, and uterine tissues. When GNAQ expression was downregulated in the hypothalamic nerve cells, the upstream genes KISS1 (kisspeptin), GPR54 (KISS1 receptor), and ER (estrogen receptor) were all upregulated, as were the downstream genes PLCB1 (phospholipase C beta 1), PRKCB (protein kinase C beta), and GNRH. At the same time, GnRH secretion levels were also upregulated. GNAQ regulated its downstream gene PLCB1 in the hypothalamic nerve cells, and directly regulated GnRH expression and secretion through the calcium and PRKC signaling pathways. GNAQ also regulated kisspeptin expression, subsequently regulating GnRH expression and secretion indirectly through the kisspeptin–GPR54 signaling pathway. Our results are of great importance for improving the reproductive performance of seasonal-estrus sheep.

Oxidative stress and female reproductive disorder: A review

Oxidative stress arises from an imbalance between the body’s pro-oxidants and antioxidants. Recently, oxidative stress has been proven a contributing factor to many female reproductive disorders including infertility, preeclampsia, endometriosis and polycystic ovarian syndrome. Herein, we review the mechanistic role of oxidative stress in inducing the most common female reproductive disorders. The current review has also highlighted the protective role of vitamin C, necessary for certain female reproductive hormone secretion by the antral follicle and corpus luteum and also essential for collagen production in ovarian tissue remodeling after ovulation, in alleviating oxidative stress and thus improving female reproductive outcomes.

Spermatogenic and Leydig Cells Induced Hyperlipidemia: A Review

Lipids are macromolecules that are very important in cell metabolism. Dietary changes and tendency to consume foods high in fat causes hyperlipidemia that increase the risk of various blood vessel abnormalities to the reproductive system. In men, normal reproductive function is closely related to the presence of the testes with the cells in them and the normal secretion of the hormone testosterone. There have been many studies on male experimental animals using high fat induction which prove that there is high fat in the circulatory system which results in metabolic and physiological disorders in the body, especially enzymes related to reproductive function, decreased secretion of reproductive hormones and abnormal structure of spermatozoa cells and degeneration of Leydig cells. Therefore, this review provides a review of the effect of high fat diets on reproductive cells, especially spermatogenic cells and Leydig cells.

Effects of Environmental and Pathological Hypoxia on Male Fertility.

Male infertility is a widespread health problem affecting approximately 6%–8% of the male population, and hypoxia may be a causative factor. In mammals, two types of hypoxia are known, including environmental and pathological hypoxia. Studies looking at the effects of hypoxia on male infertility have linked both types of hypoxia to poor sperm quality and pregnancy outcomes. Hypoxia damages testicular seminiferous tubule directly, leading to the disorder of seminiferous epithelium and shedding of spermatogenic cells. Hypoxia can also disrupt the balance between oxidative phosphorylation and glycolysis of spermatogenic cells, resulting in impaired self-renewal and differentiation of spermatogonia, and failure of meiosis. In addition, hypoxia disrupts the secretion of reproductive hormones, causing spermatogenic arrest and erectile dysfunction. The possible mechanisms involved in hypoxia on male reproductive toxicity mainly include excessive ROS mediated oxidative stress, HIF-1α mediated germ cell apoptosis and proliferation inhibition, systematic inflammation and epigenetic changes. In this review, we discuss the correlations between hypoxia and male infertility based on epidemiological, clinical and animal studies and enumerate the hypoxic factors causing male infertility in detail. Demonstration of the causal association between hypoxia and male infertility will provide more options for the treatment of male infertility

Identification of Circular RNAs in the Anterior Pituitary in Rats Treated with GnRH.

Simple SummaryThe pituitary gland, an important endocrine organ, can secrete a variety of reproductive hormones under the action of hypothalamus-secreted gonadotropin-releasing hormone. Circular RNAs are a class of RNA molecules with stable covalently closed circular structures. In this study, we performed RNA sequencing of GnRH-treated rats to identify differentially expressed circRNAs in the anterior pituitary. The results revealed 1433 related circRNAs, 14 of which were differentially expressed. We predicted targeted relationships between the differentially expressed circRNAs and FSHb-LHb-associated miRNAs. In all, a total of 14 circRNAs were identified that may act on the secretion and regulation of reproductive hormones in GnRH-treated rats.The pituitary gland, an important endocrine organ, can secrete a variety of reproductive hormones under the action of hypothalamus-secreted gonadotropin-releasing hormone (GnRH) and plays important roles in animal reproduction. Circular RNAs (circRNAs) are a class of RNA molecules with stable covalently closed circular structures. CircRNAs are equipped with miRNA response elements (MREs), which can regulate the expression of target genes by competitively binding miRNAs. However, whether the expression levels of circRNAs in the pituitary gland change under the action of GnRH and whether such changes can further affect the secretion of reproductive hormones are still unclear. In this study, we performed RNA sequencing (RNA-Seq) of GnRH-treated rats to identify differentially expressed circRNAs. The results revealed 1433 related circRNAs, 14 of which were differentially expressed. In addition, we randomly selected five differentially expressed circRNAs and tested their relative expression levels by RT-qPCR, the results of which were consistent with the RNA sequencing results. Finally, we predicted targeted relationships between the differentially expressed circRNAs and FSHb-LHb-associated miRNAs. In all, a total of 14 circRNAs were identified that may act on the secretion and regulation of reproductive hormones in GnRH-treated rats. Our expression profiles of circRNAs in the anterior pituitaries of rats treated with GnRH can provide insights into the roles of circRNAs in mammalian development and reproduction.

Effect of Giving Different Doses of Vitamin E in Feed to the Level of Gonad Maturity of Tilapia (Oreochromis niloticus)

One of the nutrients that can be given to brood feed fish to improve reproductive performance and egg quality is vitamin E. Vitamin E has a very important role in increasing fish reproduction because vitamin E functions as an antioxidant that can maintain the presence of fatty acids and prevent fat oxidation in the fish cell membrane and can accelerate the secretion of reproductive hormones. This study aims to determine the effect of vitamin E in feed at different doses on the level of gonad maturity of tilapia. The research was conducted at the Fisheries Laboratory of the Faculty of Marine and Fisheries, Udayana University from July to August 2020. The samples of fish tested were tilapia (Oreochromis niloticus) obtained from the Teratai fishing pond, Sanur Bali. Vitamin E used was Ovagrow Vit E with a vitamin E content of 50%. The CRD method (completely randomized design) was used with four treatments and three replications. The doses of vitamin E that were mixed into the feed were 0, 100, 300, and 500 mg/kg of feed. The results showed that the administration of vitamin E mixed in the feed at different doses had a significant effect on the achievement of gonad maturity level, gonad somatic index (GSI), and Fecundity (P <0.05). Provision of vitamin E at a dose of 300 mg/kg of feed was the best dose for ripening tilapia gonads. The gonad maturity level developed up to maturity stage IV, the GSI value was (3.56 ± 0.46) and the fecundity value was (1379 ± 289).

Intracerebroventricular salusin-β infusion to rats increases hypothalamus-pituitary-testicular axis hormones

Salusin-β (Sal-β), which originates from preprosalusin, is a multifunctional hormone with a peptide structure. Sal-β exists in the hypothalamus and can stimulate the pituitary gland. The present study was conducted to determine the effects of Sal-β on hormones that play roles in the male reproductive system. Forty male Wistar Albino rats were used in the study. No infusions were performed on the control group, and infusions were applied to the infusion groups (artificial cerebrospinal fluid to the sham group, 2 and 20 nM Sal-β to the experimental group) through intracerebroventricular infusion for 7 days at 10 μl/hour rate. The animals were decapitated after 7 days of infusion; and the hypothalamus, testicles, and blood tissue samples were collected. The gonadotropin-releasing hormone (GnRH) mRNA levels were determined from the hypothalamus tissues by using the Real Time-PCR Method, and the serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone levels were determined using the ELISA method. Also, Hematoxylin-Eosin Staining Method was used for histopathological evaluations in the testicle tissues. As a result, Sal-β infusion increased GnRH mRNA levels in hypothalamus tissues (p < 0.05) besides, serum LH, FSH, and testosterone levels of the rats were higher at significant levels following Sal-β infusion compared to the control and sham group (p < 0.05). In the histological examination of the testicle tissues, Sal-β application was found to decrease the seminiferous tubule diameter and germinal epithelial thickness (p < 0.05). This evidence is the first, indicating that Sal-β, which is administered to male rats with central infusion, stimulates hypothalamus and pituitary tissues, and causes increased secretion of male reproductive hormones.

Estrogen Regulation of the Molecular Phenotype and Active Translatome of AVPV Kisspeptin Neurons.

In females, ovarian estradiol (E2) exerts both negative and positive feedback regulation on the neural circuits governing reproductive hormone secretion, but the cellular and molecular mechanisms underlying this remain poorly understood. In rodents, estrogen receptor α-expressing kisspeptin neurons in the hypothalamic anteroventral periventricular region (AVPV) are prime candidates to mediate E2 positive feedback induction of preovulatory gonadotropin-releasing hormone and luteinizing hormone (LH) surges. E2 stimulates AVPV Kiss1 expression, but the full extent of estrogen effects in these neurons is unknown; whether E2 stimulates or inhibits other genes in AVPV Kiss1 cells has not been determined. Indeed, understanding of the function(s) of AVPV kisspeptin cells is limited, in part, by minimal knowledge of their overall molecular phenotype, as only a few genes are currently known to be co-expressed in AVPV Kiss1 cells. To provide a more detailed profiling of co-expressed genes in AVPV Kiss1 cells, including receptors and other signaling factors, and test how these genes respond to E2, we selectively isolated actively translated mRNAs from AVPV Kiss1 cells of female mice and performed RNA sequencing (RNA-seq). This identified >13 000 mRNAs co-expressed in AVPV Kiss1 cells, including multiple receptor and ligand transcripts positively or negatively regulated by E2. We also performed RNAscope to validate co-expression of several transcripts identified by RNA-seq, including Pdyn (prodynorphin), Penk (proenkephalin), Vgf (VGF), and Cartpt (CART), in female AVPV Kiss1 cells. Given the important role of AVPV kisspeptin cells in positive feedback, E2 effects on identified genes may relate to the LH surge mechanism and/or other physiological processes involving these cells.

Beneficial effects of a decreased meal frequency on nutrient utilization, secretion of luteinizing hormones and ovarian follicular development in gilts

BackgroundReplacement gilts are typically fed ad libitum, whereas emerging evidence from human and rodent studies has revealed that time-restricted access to food has health benefits. The objective of this study was to investigate the effect of meal frequency on the metabolic status and ovarian follicular development in gilts.MethodsA total of 36 gilts (Landrace × Yorkshire) with an age of 150±3 d and a body weight of 77.6±3.8 kg were randomly allocated into one of three groups (n = 12 in each group), and based on the group allocation, the gilts were fed at a frequency of one meal (T1), two meals (T2), or six meals per day (T6) for 14 consecutive weeks. The effects of the meal frequency on growth preference, nutrient utilization, short-chain fatty acid production by gut microbial, the post-meal dynamics in the metabolic status, reproductive hormone secretions, and ovarian follicular development in the gilts were measured.ResultsThe gilts in the T1 group presented a higher average daily gain (+ 48 g/d, P < 0.05) and a higher body weight (+ 4.9 kg, P < 0.05) than those in the T6 group. The meal frequency had no effect on the apparent digestibility of dry matter, crude protein, ether extract, ash, and gross energy, with the exception that the T1 gilts exhibited a greater NDF digestibility than the T6 gilts (P < 0.05). The nitrogen balance analysis revealed that the T1 gilts presented decreased urine excretion of nitrogen (− 8.17 g/d, P < 0.05) and higher nitrogen retention (+ 9.81 g/d, P < 0.05), and thus exhibited higher nitrogen utilization than the T6 gilts. The time-course dynamics of glucose, α-amino nitrogen, urea, lactate, and insulin levels in serum revealed that the T1 group exhibited higher utilization of nutrients after a meal than the T2 or T6 gilts. The T1 gilts also had a higher acetate content and SCFAs in feces than the T6 gilts (P < 0.05). The age, body weight and backfat thickness of the gilts at first estrous expression were not affected by the meal frequency, but the gilts in the T1 group had higher levels of serum luteinizing hormone on the 18th day of the 3rd estrus cycle and 17β-estradiol, a larger number of growing follicles and corpora lutea, and higher mRNA expression levels of genes related to follicular development on the 19th day of the 3rd estrus cycle.ConclusionsThe current findings revealed the benefits of a lower meal frequency equal feed intake on nutrient utilization and reproductive function in replacement gilts, and thus provide new insights into the nutritional strategy for replacement gilts, and the dietary pattern for other mammals, such as humans.