Serum Levels Of Gonadotropin-releasing Hormone Research Articles

Impact of polyamine supplementation on GnRH expression, folliculogenesis, and puberty onset in young mice

BackgroundThe hypothalamic-pituitary-gonadal (HPG) axis is pivotal in regulating reproductive functions, with gonadotropin-releasing hormone (GnRH) acting as a central regulator. Recently, polyamines have been shown to regulate the HPG axis, including GnRH expression and ovarian biology in old and adult rodents. The present study firstly highlights the age-specific variation in the polyamine and their corresponding biosynthetic enzymes in the ovary during aging, and further, the study focuses on the effect of polyamines, putrescine, and agmatine, in young female mice. Method and resultImmunofluorescence analysis revealed age-related differences in the expression of ornithine decarboxylase 1 (ODC1), spermine (SPM), and spermidine (SPD) in the ovaries, with adult mice exhibiting significantly higher expression levels compared to young and old mice. Likewise, qPCR analysis showed the mRNA levels of Odc1, Spermidine synthase (Srm), and Spermine synthase (Sms) show a significant increase in adult ovaries, which is then followed by a significant decline in old age. Histological examination demonstrated morphological alterations in the ovaries with age, including decreased follicle numbers and increased stromal cells in old mice. Furthermore, treatment with putrescine, a polyamine, in young mice resulted in larger ovaries and increased follicle numbers compared to controls. Additionally, serum levels of gonadotropin-releasing hormone (GnRH) and progesterone (P4) were measured, showing elevated levels in polyamine-treated mice. GnRH mRNA expression also increased significantly. Gene expression analysis revealed upregulation of genes associated with folliculogenesis such as Fshr, Bmp15, Gdf9, Amh, Star, Hsdb3, and Plaur in the ovaries and onset of puberty such as Tac2, and Kiss1, and a decrease in Mkrn3 in the hypothalamus of polyamine-treated mice. ConclusionThis study investigates the effect of polyamines in young immature female mice, shedding light on their role in upregulating GnRH, and enhancing folliculogenesis. Overall, these findings suggest that polyamines play a crucial role in ovarian aging and HPG axis regulation, offering potential therapeutics to reinstate fertility in reproductively challenged individuals.

The effect of aqueous extract of orchid root on the structure of ovary and hypothalamic-pituitary-gonadal hormones in polycystic ovary syndrome rat model: An experimental study.

Some medical conditions, including polycystic ovarian syndrome (PCOs), may lead to infertility. In PCOs, hormonal imbalance is significant. Antioxidants such as natural antioxidants have many health benefits, including positive effects on hormone production. Since herbal medicines are more acceptable to people, the present study was designed to evaluate the effect of an aqueous extract of orchid (SA), with antioxidative effects, on the structure of the ovary and the hypothalamic-pituitary-gonadal axis hormones and free testosterone in PCOs rats. In this experimental study, 64 healthy female Wistar rats (180-200 gr) were randomly divided into 60 and 89 day control groups, PCOs, and 4 PCOs + SA groups that received 40, 80, 160, and 320 mg/kg of SA. Serum levels of gonadotropin-releasing hormone, estrogen, progesterone, testosterone, follicle-stimulating hormone, and luteinizing hormone were measured. In addition, the ovaries were extracted and examined histologically. The amount of primordial, primary, secondary, and Graafian follicles and serum levels of follicle-stimulating hormone and progesterone hormones decreased in PCOs groups, while atretic follicles and the serum levels of gonadotropin-releasing hormone, luteinizing hormone, estrogen, and free testosterone were increased. SA at different doses regulated hormonal and histological imbalances caused by PCOs, and 320 mg/kg was the most effective. The aqueous extract of orchids root can have a positive effect on the improvement of polycystic ovary syndrome. This effect can be achieved by regulating the level of sex hormones and correcting follicular abnormalities in the ovarian tissue.

Characterization of MicroRNA expression profiles in the ovarian tissue of goats during the sexual maturity period

BackgroundThe ovary is an important reproductive organ in mammals, and its development directly affects the sexual maturity and reproductive capacity of individuals. MicroRNAs (miRNAs) are recognized as regulators of reproductive physiological processes in various animals and have been shown to regulate ovarian development through typical targeting and translational repression. However, little is known about the regulatory role of miRNAs in ovarian tissue development during sexual maturity in goats. To comprehensively profile the different physiological stages of sexual maturation in goats, we performed small-RNA sequencing of ovarian tissue samples collected at four specific time points (1 day after birth (D1), 2 months old (M2), 4 months old (M4), and 6 months old (M6)). In addition, we used ELISAs to measure serum levels of reproductive hormones to study their temporal changes.ResultsThe results showed that serum levels of gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, oestradiol, progesterone, oxytocin, and prolactin were lower in goats at the D1 stage than at the other three developmental stages (P < 0.05). The secretion patterns of these seven hormones show a similar trend, with hormone levels reaching their peaks at 4 months of age. A total of 667 miRNAs were detected in 20 libraries, and 254 differentially expressed miRNAs and 3 groups of miRNA clusters that had unique expression patterns were identified (|log2-fold change|> 1, FDR < 0.05) in the 6 comparison groups. RT‒qPCR was employed to confirm that the expression pattern of the 15 selected miRNAs was consistent with the Illumina sequencing results. Gene ontology analyses revealed significant enrichment of GO terms such as cell proliferation regulation, epithelial cell development, and amino acid transport, as well as important signaling pathways including the MAPK signaling pathway, the PI3K-Akt signaling pathway, and the oestrogen signaling pathway. Further miRNA‒mRNA regulation network analysis revealed that 8 differentially expressed miRNAs (chi-miR-1343, chi-miR-328-3p, chi-miR-877-3p, chi-miR-296-3p, chi-miR-128-5p, chi-miR-331-3p, chi-miR-342-5p and chi-miR-34a) have important regulatory roles in ovarian cell proliferation, hormone secretion and metabolism-related biological processes.ConclusionsOverall, our study investigated the changes in serum hormone and miRNA levels in the ovaries. These data provide a valuable resource for understanding the molecular regulatory mechanisms of miRNAs in ovarian tissue during the sexual maturity period in goats.

Postnatal feeding with high-fat combined with high-glucose diet induces precocious puberty in Sprague‒Dawley rat pups

With economic development and overnutrition, including high-fat diets (HFD) and high-glucose diets (HGD), the incidence of obesity in children is increasing, and thus, the incidence of precocious puberty is increasing. Therefore, it is of great importance to construct a suitable animal model of overnutrition-induced precocious puberty for further in-depth study. Here, we fed a HFD, HGD, or HFD combined with a HGD to pups after P-21 weaning, while weaned pups fed a normal diet served as the control group. The results showed that HFD combined with a HGD increased the body weight (BW) of weaned rat pups. In addition, a HFD, HGD, and HFD combined with a HGD lowered the age at which vaginal opening occurred and accelerated the vaginal cell cycle. Furthermore, a HFD combined with a HGD increased the weight of the uterus and ovaries of weaned rat pups. Additionally, a HFD combined with a HGD promoted the development of reproductive organs in weaned female rat pups. Ultimately, a HFD combined with a HGD was found to elevate the serum levels of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), follicle stimulating hormone (FSH), leptin, adiponectin, and oestradiol (E2) and increase hypothalamic GnRH, Kiss-1, and GPR54 expression levels in weaned female rat pups. The current study found that overnutrition, such as that through a HFD combined with HGD, could induce precocious puberty in weaned female rat pups. In addition, a rat model of overnutrition-induced precocious puberty was established.

Synergistic Action of Virgin Coconut Oil and Clomiphene in Reversing Endocrine Dysregulation in Letrozole-Model of Polycystic Ovarian Syndrome in Rats: Role of Nrf2/HMOX-1 Pathway.

Polycystic ovarian syndrome (PCOS) is an endocrine disorder in women's reproductive age. Currently, the pathophysiology of PCOS is unclear, and the limited treatment options are unsatisfactory. Virgin coconut oil (VCO) is functional food oil associated with pharmacological effects in reproductive disorders. Therefore, we aimed to evaluate whether VCO could enhance clomiphene (CLO) therapy against PCOS in female rats. Rats were randomly divided: (1) Control, (2) PCOS model, (3) PCOS + CLO, (4) PCOS + VCO, and (5) PCOS + CLO + VCO. The PCOS was induced via daily letrozole (1 mg/kg, orally) administration for 21 days. After the PCOS induction, CLO, VCO, and CLO + VCO were administered from days 22 to 36. Serum levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, estrogen, progesterone, and prolactin were estimated. Polymerase chain reaction gene expression for nuclear factor-erythroid-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), catalase (CAT), glutathione reductase (GSR), LH receptor (LHr), androgen receptor (AR), tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and caspase-3 were analyzed. The letrozole-induced PCOS caused considerable increases in GnRH, LH, prolactin, estrogen, and testosterone, whereas FSH decreased significantly compared to the control. The gene expression of Nrf2, HO-1, CAT, and GSR were markedly diminished, while IL-1β, TNF-α, caspase-3, AR, and LHr prominently increased compared to control. Interestingly, the CLO and VCO separately exerted anti-inflammatory and endocrine balance effects. However, VCO-enhanced CLO effect in LH, prolactin and testosterone, Nrf2, HO-1, CAT, GSR, and AR. VCO may synergize with CLO to depress hyperandrogenism and oxidative inflammation in PCOS.

Perinatal exposure to low doses of cypermethrin induce the puberty-related hormones and decrease the time to puberty in the female offspring.

Pyrethroid insecticides are ubiquitously detected in environmental media, food, and urine samples. Our previous epidemiological study reported a correlation between increased pyrethroid exposure and delayed pubertal development in Chinese girls. In this study, we further investigated the effects of perinatal exposure to low doses of cypermethrin (CP) on pubertal onset and hypothalamic-pituitary-ovarian axis in the female mice offspring. The treatment of CP with 60μg/kg/day from gestation day 6 (GD6) to postnatal day 21 (PND21) significantly decreased the time to puberty in the female offspring. Exposure of CP increased the serum levels of gonadotropin-releasing hormone (GnRH) and the expression of GnRH genes in a dose-dependent manner in the female offspring. CP also induced the serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as well as the expression of gonadotropin subunit genes [LHβ, FSHβ, and chorionic gonadotropin α (Cgα)]. Furthermore, CP induced serum estradiol (E2) levels and the expression of steroidogenesis-related genes [steroidogenic acute regulatory (StAR) and Cytochrome p 450, family 11, subfamily A, polypeptide 1 (CYP11A1)] in the ovary. In accordance with the in vivo tests, administration of CP (6.7, 20, and 60μg/L) stimulated a dose-dependent increase in the synthesis and secretion of the puberty-related hormones in the explants of hypothalamus, pituitary, and ovary. The interference with calcium channels in the ovary may be responsible for CP-induced pubertal onset. Our study provided evidence that perinatal exposure to low doses of CP induced puberty-related hormones and decreased the time to puberty in the female offspring.

Direct effect of RFRP‑3 microinjection into the lateral ventricle on the hypothalamic kisspeptin neurons in ovariectomized estrogen‑primed rats

RFamide-related peptide-3 (RFRP-3) may be involved in the inhibition of kisspeptin, but there is no direct evidence that RFRP-3 can directly act on kisspeptin neurons. The present study aimed to investigate the role and mechanism of RFRP-3 and kisspeptin in the hypothalamic-pituitary reproductive axis. In order to detect the expression and localization of RFRP-3 and kisspeptin in dorsomedial hypothalamic nucleus, double immunofluorescence method combined with confocal microscopy were performed. RFRP-3 was injected into the lateral ventricle of ovariectomized estrogen primed rats. Blood and brain tissues were collected at 60-, 120-, 240- and 360-min. Serum levels of gonadotropin-releasing hormone, luteinizing hormone and follicle-stimulating hormone were detected by ELISA. Kisspeptin expression in hypothalamus was detected by western blotting. Finally, surface plasmon resonance was used to verify whether RFRP-3 can directly interact with kisspeptin. Confocal images indicated that RFRP-3 and kisspeptin were co-expressed in the same neurons in the hypothalamus of ovariectomized estrogen-primed rats. Serum concentrations of gonadotropin-releasing hormone, luteinizing hormone and follicle-stimulating hormone were demonstrated to be significantly reduced following microinjection of RFRP-3 into the lateral ventricle for 60, 120, 240 and 360 min compared with the corresponding saline groups. The expression levels of kisspeptin in hypothalamus were gradually decreased following microinjection of RFRP-3 into the lateral ventricle. In addition, the affinity constant (KD) of RFRP-3 binding to kisspeptin was 6.005x10-5 M, indicating that RFRP-3 bound directly to kisspeptin in the range of protein-protein binding strength (KD, 10-3-10-6 M). In conclusion, RFRP-3 may regulate the hypothalamic-pituitary reproductive axis by inhibiting the expression of hypothalamic kisspeptin and direct binding.

Effects of Thyroid Dysfunction on Reproductive Hormones in Female Rats.

Thyroid hormones (THs) play a critical role in the development of ovarian cells. Although the effects of THs on female reproduction are of great interest, the mechanism remains unclear. We investigated the effects of TH dysregulation on reproductive hormones in rats. Propylthiouracil (PTU) and L-thyroxine were administered to rats to induce hypo- and hyperthyroidism, respectively, and the reproductive hormone profiles were analyzed by radioimmunoassay (RIA). Ovarian histology was evaluated with hematoxylin and eosin (H&E) staining, and gene protein level or mRNA content was analyzed by western blotting or reverse transcription polymerase chain reaction (RT-PCR). The serum levels of gonadotropin releasing hormone (GnRH) and follicle stimulating hormone (FSH) in both rat models were significantly decreased on day 21, although there were no significant changes at earlier time points. There were no significant differences in luteinizing hormone (LH) or progesterone (P4) levels between the treatment and the control groups. Both PTU and L-thyroxine treatments downregulated estradiol (E2) concentrations; however, the serum testosterone (T) level was increased only in hypothyroid rats at day 21. In addition, the expression levels of FSH receptor, cholesterol side-chain cleavage enzyme (P450scc), and steroidogenic acute regulatory protein (StAR) were decreased in both rat models. Moreover, the onset of puberty was significantly delayed in the hypothyroid group. These results provide evidence that TH dysregulation alters reproductive hormone profiles, and that the initiation of the estrous cycle is postponed in hypothyroidism.

Microcystin-LR causes sexual hormone disturbance in male rat by targeting gonadotropin-releasing hormone neurons

Microcystin-LR (MC-LR), which generates strong reproductive toxicity, reduces serum testosterone level without directly damaging Leydig cells. The purpose of this study was to identify the target cells of MC-LR in the rat hypothalamic-pituitary axis and to investigate the underlying mechanisms. We found that the gonadotropin-releasing hormone (GnRH) neurons were the direct target of MC-LR. In vivo results showed that upon exposure to rats, cells around the third ventricle of hypothalamus underwent apoptosis. Gnrh1 expression was steadily decreased. The serum levels of GnRH, luteinizing hormone, follicle-stimulating hormone and testosterone showed a similar pattern of early-stage increase and late-stage decline. After treatment with MC-LR in immortalized hypothalamic (GT1-7) neurons, increase in cellular Ca2+ and ATP resulted in downregulation of the transcriptional activators Oct-1, Otx-2, Pbx1a and Dlx2, and upregulation of the transcriptional repressor c-Jun, which may mechanistically account for the downregulation of GnRH synthesis. Ca2+ and ATP could also stimulate the release of GnRH, contributing to its unique serum release pattern.

Effects of Morinda officinalis Polysaccharide on Experimental Varicocele Rats.

Morinda officinalis is a traditional Chinese herbal medicine, which has been used to tonify the kidney and strengthen yang for a long time in China. In this study, the effects of M. officinalis Polysaccharide (MOP) on experimental varicocele adolescent rats were investigated. The result showed that varicocele destroyed the structure of the seminiferous epithelium and decreased the TJ protein expression (Occludin, Claudin-11, and ZO-1), testosterone (T) concentration in the left testicular tissue and serum, and serum levels of inhibin B (INHB), while increasing the levels of cytokines (TGF-β3 and TNF-α) in the left testicular tissue, as well as serum levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and antisperm antibody (AsAb). MOP repaired the damaged seminiferous epithelium and TJ and reduced the levels of cytokines (TGF-β3 and TNF-α) as well as serum levels of GnRH, FSH, LH, and AsAb, while upregulating TJ protein expression, T level in the left testicular tissue and serum, and serum INHB levels. In summary, we conclude that MOP promotes spermatogenesis and counteracts the varicocele-induced damage to the seminiferous epithelium and TJ, probably via decreasing cytokines (TGF-β3 and TNF-α) levels and regulating the abnormal sex hormones levels in experimental varicocele rats.

Effects of subcutaneous administration of daidzein on blastocyst implantation in rats

The study was conducted to investigate the effects of phytoestrogen daidzein on blastocyst implantation in rats. Following successful mating, female rats were given daidzein by subcutaneous administration at the dose of 0 (vehicle control, n = 15), 50 mg/kg body weight ( n = 15) and 150 mg/kg body weight ( n = 15) daily on day 1–7 of pregnancy and were sacrificed on day 8 of gestation. The results revealed that high-dose treatment (150 mg/kg body weight) significantly diminished the rate of blastocyst implantation and serum levels of gonadotropin-releasing hormone (GnRH), progesterone, and gonadotropins (FSH and LH), meanwhile the serum level of beta endorphin increased significantly. These effects were not observed in the low-dose treatment group (50 mg/kg body weight). The results of this study suggested that the anti-implantation effects of daidzein are probably caused by the interference of the hypothalamus-pituitary-gonadal axis which is involved in the implantation process.

Gonadotropin-releasing hormone (GnRH) receptor dynamics and gonadotrope responsiveness during and after continuous GnRH stimulation.

Gonadotrope responsiveness, serum and tissue levels of luteinizing hormone (LH), and tissue concentration of gonadotropin-releasing hormone (GnRH) receptors in ovariectomized rats were determined during and after continuous GnRH stimulation. Intraperitoneal placement of GnRH-containing osmotic minipumps for 96 h established a rate of GnRH delivery (1 microgram/h) that resulted in stable serum levels of GnRH (500-700 pg/ml). Secretion of LH increased 8-fold within 6 h; however, serum LH returned to pretreatment levels by 24 h, even with continued GnRH stimulation. Tissue concentration of LH was depressed within 48 h of initiation of treatment but levels were restored by 96 h. Tissue levels of GnRH receptor remained elevated during the first 6 h of treatment but were reduced by 60% within 24 h and remained depressed for the duration of treatment. Gonadotrope responsiveness 48 h and 96 h after initiation of treatment was reduced by 50% and 90%, respectively. Removal of the GnRH delivery vehicle resulted in rapid disappearance of GnRH from serum. Dramatic reduction (75%) in circulating levels of LH, and a 2-fold increase in tissue levels of LH and in GnRH receptor concentration were noted within 6 h of minipump removal. Although tissue concentration of GnRH receptor returned to pretreatment levels within 48 h of minipump removal, both basal LH secretion and gonadotrope responsiveness remained depressed even 96 h after cessation of continuous GnRH stimulation. These data indicate that GnRH can "down regulate" its receptor, gonadotrope responsiveness is not obligatorily linked to receptor concentration, and desensitization that follows hyperstimulation represents effects directed at post-receptor loci.

Serum levels of luteinizing hormone and gonadotropin-releasing hormone in cycling, castrated and anestrous ewes.

Blood samples were collected at 4-min intervals for 4 hr from 2 ewes on the day of estrus and 2 ewes castrated 90 and 120 days previously. Serum levels of luteinizing hormone (LH) and gonadotropin-releasing hormone (Gn-RH) were determined by double antibody radioimmunoassays. Samples were collected during a portion of the preovulatory LH surge in each ewe with LH levels ranging from <5 ng/ml to=300 ng/ml. Gn-RH levels ranged from 15 to 96 pg/ml and were not significantly elevated when LH levels were high. LH in castrated ewes ranged from 2.7 to 13.3 ng/ml while Gn-RH ranged from 119 to 368 pg/ml during the 4-hr sampling period. There was no apparent correlation between serum levels of LH and Gn-RH. Both cycling ewes and castrated ewes demonstrated rhythmic oscillations in serum levels of Gn-RH with peaks occurring at a frequency of 15.4 ± 4.0 min (SD). Four anestrousewes were given an intramuscular injection of 100μ g 17β-estradiol and blood samples were collected at 10-min intervals from 1 hr pre-injection until10 hr post-injection, at 5-min intervals from 10 to 16 hr and at 10-min intervals from 16 to 24 hr post-injection. LH, Gn-RH and follicle-stimulating hormone (FSH) were quantified in these samples. Peak levels of LH (mean = 184 ng/ml) occurred in 3 of the 4 ewes simultaneously with peak levels of FSH (mean = 621 ng/ml). Gn-RH levels did not change significantly throughout the sampling period in those ewes that responded to 17β-estradiol with elevated LH levels, nor in the ewe which did not respond. It was concluded that increased levels of Gn-RH in the peripheral circulation were not responsible for LH release during estrus in cycling ewes, in castrated ewes, or in anestrous ewes treated with 17β-estradiol. (Endocrinology94: 713, 1974)

Serum levels of gonadotropin-releasing hormone (Gn-RH) during the estrous cycle and in pentobarbital-treated rats.

4-day cycling rats were sacrificed by decapitationduring the estrous cycle from 08.00 through 18.00 h. Additional rats were given i.p. pentobarbital injections at 13.30 on proestrus and were then sacrificed between 14.00 and 18.00. Serum levels of LH and Gn-RH were quantitated by radioimmunoassay. A peak in serum Gn-RH levels was observed between 08.00 and 16.00 on each day of the estrous cycle. Pentobarbital treatment blocked the pre-ovulatory LH surge on proestrus and significantly reduced (p<0.05) serum Gn-RH levels between 14.00 and 16.00. However, the major portion of Gn-RH release had already occurred prior to pentobarbital administration.