Does the activation of sea bass GnIH receptor modulate GnRH receptor signaling?

Previous studies have revealed the stimulatory and inhibitory actions of gonadotropin-releasing hormone (GnRH) and gonadotropin-inhibitory hormone (GnIH) on the control of reproduction in European sea bass (Dicentrarchus labrax) and other vertebrates, respectively. However, information on the possible interactions between GnRH and GnIH on cell signaling is sparse in vertebrates. In the current study, we investigated if activation of sea bass GnIH receptor (GnIHR) can interfere with GnRH receptor II-1a (GnRHR-II-1a) involving the PKA pathway. Our results showed that GnIH and GnRH functioned via their cognate receptors, respectively. However, it appears that neither GnIH1 nor GnIH2 can block GnRH/GnRHR-II-1a-induced PKA signaling in sea bass. This is the first study to examine the potential interactions of GnIH with GnRH receptor signaling in teleosts. Further research seems necessary to shed light on unknown interactions in other signaling pathways and other GnIH/GnRH receptors involved in the physiological functions of these two relevant neuropeptides, not only in sea bass but also in other species.

Unraveling Hypothalamus-Pituitary dysregulation: Hypergonadotropism in F1 progeny due to prenatal exposure to hexavalent chromium.

The endocrine disruptor hexavalent chromium [Cr(VI)] is a proven reproductive toxicant. We recently demonstrated that prenatal Cr(VI) exposure causes testicular resistance to gonadotropins, resulting in hypergonadotropic hypoandrogenism in F1 rats. However, the mechanism driving hypergonadotropism in F1 rats exposed to Cr(VI) prenatally remains an enigma. Therefore, we hypothesized that 'Prenatal Cr(VI) exposure may disrupt steroid hormones-mediated negative feedback regulation of the hypothalamic GnRH, and its receptor in the pituitary of F1 rats, leading to hypergonadotropism.' We administered potassium dichromate (50, 100, or 200 mg/L) to pregnant rats through drinking water between days 9 and 14, and their male F1 offspring were euthanized at 60 days of age. Prenatal Cr(VI) exposure in F1 rats resulted in the accumulation of Cr in the hypothalamus and pituitary. Western blot detected decreased hypothalamic GnRH, Kisspeptin1, and its receptor GPR54, along with diminished ERα, AR, aromatase, and 5α reductase, and GnRH regulatory transcription factors Pit-1 and GATA-4 proteins. Immunohistochemical studies revealed increased immunopositivity of GnRH receptor, AR, 5α reductase, ERα, ERß, and aromatase proteins in the pituitary, whereas decreased Kisspeptin1, GPR54, and inhibin ß. Our findings imply that Cr(VI) exposure during the prenatal period disrupts the hypothalamic Kisspeptin-GPR54-Pit-1/GATA4-GnRH network, boosting the pituitary GnRH receptor. We conclude that prenatal exposure to Cr(VI) alters GnRH expression in the hypothalamus and its receptor in the pituitary of F1 progeny through interfering with the negative feedback effect of androgens and estrogens.

The clinical trial of alternative relugolix administration for uterine leiomyoma prior to surgically treatment: a study protocol for Non-Adverse Relugolix Administration (NARA) trial.

BACKGROUND: Uterine leiomyomas are common for reproductive-aged women and affect women's quality of life due to heavy menstrual bleeding or dysmenorrhea. Leiomyomas grow according to estradiol exposure and decrease after post-menopause. In case serious symptoms are caused by leiomyomas, pharmacotherapy or surgical treatment is proposed. Prior to surgical treatment, pharmacotherapies aimed at the reduction of leiomyoma and uterine volume or improvement of anemia are introduced to conduct minimum invasive surgery (i.e., to reduce blood loss or surgical duration). Recently, relugolix (40 mg orally once daily) as a gonadotropin-releasing hormone (GnRH) receptor antagonist has proved its sufficient efficacy in suppressing estradiol levels without the transient estradiol flare-up compared with GnRH agonist. However, long-term administration should not be permitted liable to for climacteric disorder or osteoporosis, and evidence is lacking on the actual efficacy and extent of adverse effects of the every-other-day dosing regimen. This trial aimed to prove non-inferiority in volume reduction effect on leiomyoma and safety (i.e., reduction of adverse effects) by every-other-day administration after 2 months of everyday administration compared to daily administration throughout the duration. METHODS: A minimization adaptive randomized control trial (RCT) will be conducted. Patients (over 20 years old) harboring leiomyoma who will be undergoing surgical treatment will be invited to participate. Patients who are enrolled in the intervention group will receive every-other-day administration for 16 weeks after 8 weeks of daily administration. Patients who are enrolled in the control group will receive daily throughout the 24 weeks. The primary outcome is the leiomyoma volume reduction, and the secondary endpoints are the reduction of uterine volume, the occurrence of the climacteric disorder, genital bleeding days, change rate of serum hormone or bone turnover markers, and bone mineral density after 24 weeks compared to before administration. DISCUSSION: This study aims to prove both the non-inferiority in leiomyoma volume reduction and superiority in adverse effects occurrence reduction, which will provide a novel method to escape adverse effects while maintaining the effect of leiomyoma reduction. TRIAL REGISTRATION: Japan Registry of Clinical Trials jRCTs051230078. Registered on 26 July 2023.

Gonadotropin-releasing hormone-like receptor 2 inversely regulates somatic proteostasis and reproduction in Caenorhabditis elegans.

The quality control machinery regulates the cellular proteome to ensure proper protein homeostasis (proteostasis). In Caenorhabditis elegans, quality control networks are downregulated cell-nonautonomously by the gonadal longevity pathway or metabolic signaling at the onset of reproduction. However, how signals are mediated between the gonad and the somatic tissues is not known. Gonadotropin-releasing hormone (GnRH)-like signaling functions in the interplay between development and reproduction and have conserved roles in regulating reproduction, metabolism, and stress. We, therefore, asked whether GnRH-like signaling is involved in proteostasis collapse at the onset of reproduction. Here, we examine whether C. elegans orthologues of GnRH receptors modulate heat shock survival. We find that gnrr-2 is required for proteostasis remodeling in different somatic tissues during the transition to adulthood. We show that gnrr-2 likely functions in neurons downstream of the gonad in the gonadal-longevity pathway and modulate the somatic regulation of transcription factors HSF-1, DAF-16, and PQM-1. In parallel, gnrr-2 modulates egg-laying rates, vitellogenin production, and thus reproductive capacity. Taken together, our data suggest that gnrr-2 plays a GnRH-associated role, mediating the cross-talk between the reproduction system and the soma in the decision to commit to reproduction.

Determination of Half-lives of Circulating FSH and LH Glycoforms in Women During GnRH Receptor Blockade.

CONTEXT: Both FSH and LH circulate as 2 glycoforms, differing in number of glycans: low-N-glycosylated glycoforms, FSHtri and LHdi, and fully N-glycosylated glycoforms, FSHtetra and LHtri. OBJECTIVES: To determine the half-lives of endogenous circulating gonadotropin glycoforms in women during GnRH receptor blockade. DESIGN/PARTICIPANTS: Serum samples were collected in 8 healthy women before and up to 20 hours after administration of the NAL-GLU GnRH antagonist. Three women were in early follicular phase, 2 at mid-cycle phase, and 3 were postmenopausal. MAIN OUTCOME MEASURES: The half-life of each glycoform was estimated by monoexponential decay for FSH (n = 8) and LH (n = 5). Data were analyzed using paired t tests. RESULTS: Half-lives in the circulation of low-N-glycosylated glycoforms of both FSH and LH were shorter than those of the fully N-glycosylated glycoforms (mean; range, FSHtri 343; 116-686 minutes vs FSHtetra 757; 436-1038, minutes, P = 0.0003; LHdi 125, 84-198 minutes vs LHtri 164, 107-235 minutes, P = 0.004). The half-lives of low-and fully N-glycosylated forms of LH were shorter than the corresponding half-lives of FSH glycoforms, P = 0.0008. CONCLUSIONS: For both FSH and LH, low-N-glycosylated glycoforms disappeared from the circulation faster than the fully N-glycosylated. The half-lives of low and fully N-glycosylated forms of LH were shorter than the corresponding half-lives of FSH. The estimated values for half-life in the circulation of total FSH and total LH will depend on the relative amounts of the 2 glycoforms of each hormone and their individual disappearance rates in circulation.

The roles of GnRH in the human central nervous system.

It is widely known that GnRH plays a role in facilitating reproductive function via the HPG axis, and this was once believed to be its only function. However, over the last several decades important neuromodulatory roles of GnRH in multiple brain functions have been elucidated. Multiple GnRH isoforms and receptors have been detected outside the HPG-axis across different species. In this review, we focus on the human CNS where GnRH I and II isoforms and a functional GnRH I receptor have been isolated. We first describe the traditional understanding of GnRH within the hypothalamus and the pituitary and current clinical use of GnRH analogues. We then review the location and function of GnRH-producing neurons and receptors located outside the HPG axis. We next review the GnRH I and II neuron location and quantity and GnRH I receptor gene expression throughout the human brain, using the Allen Brain Map Atlas. This analysis demonstrates a wide expression of GnRH throughout the brain, including prominent expression in the basal forebrain and cerebellum. Lastly, we examine the potential role of GnRH in aging and inflammation and its therapeutic potential for neurodegenerative disease and spinal cord lesions.

Deletion of Gαq/11 or Gαs Proteins in Gonadotropes Differentially Affects Gonadotropin Production and Secretion in Mice.

Gonadotropin-releasing hormone (GnRH) regulates gonadal function via its stimulatory effects on gonadotropin production by pituitary gonadotrope cells. GnRH is released from the hypothalamus in pulses and GnRH pulse frequency differentially regulates follicle-stimulating hormone (FSH) and luteinizing hormone (LH) synthesis and secretion. The GnRH receptor (GnRHR) is a G protein-coupled receptor that canonically activates Gα q/11-dependent signaling on ligand binding. However, the receptor can also couple to Gα s and in vitro data suggest that toggling between different G proteins may contribute to GnRH pulse frequency decoding. For example, as we show here, knockdown of Gα s impairs GnRH-stimulated FSH synthesis at low- but not high-pulse frequency in a model gonadotrope-derived cell line. We next used a Cre-lox conditional knockout approach to interrogate the relative roles of Gα q/11 and Gα s proteins in gonadotrope function in mice. Gonadotrope-specific Gα q/11 knockouts exhibit hypogonadotropic hypogonadism and infertility, akin to the phenotypes seen in GnRH- or GnRHR-deficient mice. In contrast, under standard conditions, gonadotrope-specific Gα s knockouts produce gonadotropins at normal levels and are fertile. However, the LH surge amplitude is blunted in Gα s knockout females and postgonadectomy increases in FSH and LH are reduced both in males and females. These data suggest that GnRH may signal principally via Gα q/11 to stimulate gonadotropin production, but that Gα s plays important roles in gonadotrope function in vivo when GnRH secretion is enhanced.

GnRH receptor-activating autoantibodies in polycystic ovary syndrome: identification of functional epitopes and development of epitope mimetic inhibitors.

PURPOSE: We have recently demonstrated that gonadotrophin-releasing hormone receptor-activating autoantibodies (GnRHR-AAb) are associated with polycystic ovary syndrome (PCOS). The aim of this study was to map the antigenic epitopes of GnRHR-AAb from PCOS patients, and develop retro-inverso peptide inhibitors that specifically target GnRHR-AAb. METHODS: Serum samples from ten GnRHR-AAb-positive PCOS patients and ten GnRHR-AAb-negative healthy controls were tested. Epitope mapping for GnRHR-AAb was performed using a set of 11 overlapping octapeptides spanning the second extracellular loop of GnRHR. Antibody-blocking effect of the designed retro-inverso peptide inhibitors was evaluated in a cell-based bioassay. RESULTS: Two peptide sequences, FSQCVTHC and HCSFSQWW, were found to react with all PCOS sera, but not with control sera. Two retro-inverso peptides that mimic the identified epitopes, d-CHTVCQSF and d-WWQSFSCH, significantly inhibited PCOS serum IgG-induced GnRHR activation. One of these two peptide inhibitors, d-CHTVCQSF, largely suppressed autoantibody-induced GnRHR activation, suggesting that the epitope sequence FSQCVTHC may be a major functional target of GnRHR-AAb. CONCLUSION: We have identified a dominant functional epitope for GnRHR-AAb associated with PCOS, and demonstrated effective blocking of GnRHR-AAb activity with epitope-mimicking retro-inverso peptide inhibitors. These proteolytically stable decoy peptides may have important therapeutic implications in subjects who harbor these autoantibodies.

Gonadotrophin-releasing hormone and kisspeptin: It takes two to tango.

Kisspeptin (Kp), a family of peptides comprising products of the Kiss1 gene, was discovered 20 years ago; it is recognised as the major factor controlling the activity of the gonadotrophin-releasing hormone (GnRH) neurones and thus the activation of the reproductive axis in mammals. It has been widely documented that the effects of Kp on reproduction through its action on GnRH neurones are mediated by the GPR54 receptor. Kp controls the activation of the reproductive axis at puberty, maintains reproductive axis activity in adults and is involved in triggering ovulation in some species. Although there is ample evidence coming from both conditional knockout models and conditional-induced Kp neurone death implicating the Kp/GPR54 pathway in the control of reproduction, the mechanism(s) underlying this process may be more complex than a sole direct control of GnRH neuronal activity by Kp. In this review, we provide an overview of the recent advances made in elucidating the interplay between Kp- and GnRH- neuronal networks with respect to regulating the reproductive axis. We highlight the existence of a possible mutual regulation between GnRH and Kp neurones, as well as the implication of Kp-dependent volume transmission in this process. We also discuss the capacity of heterodimerisation between GPR54 and GnRH receptor (GnRH-R) and its consequences on signalling. Finally, we illustrate the role of mathematical modelling that accounts for the synergy between GnRH-R and GPR54 in explaining the role of these two receptors when defining GnRH neuronal activity and GnRH pulsatile release.

Membrane translocation and activation of GnRH receptor sensitize prostate cancer cells to radiation.

BACKGROUND: GnRH analogs are widely used as neoadjuvant agents for radiotherapy in prostate cancer (PCa) patients, with well-documented effects in reducing tumor bulk and increasing progression-free survival. GnRH analogs act locally in the prostate by triggering apoptosis of PCa cells via activation of the GnRH receptor (GnRHR). During PCa progression, the distribution of GnRHR within the cell is altered, with reduced expression in the cell membrane and remaining sequestered in the endoplasmic reticulum. Pharmacoperone IN3 is able to relocalize GnRHR to the cell membrane. The aim of this study was to evaluate the effect of radiation on PCa cells pretreated with leuprolide, alone or in combination with IN3, as radiosensitizers. MATERIAL AND METHODS: PC3 and human PCa primary cell cultures were treated with IN3 for 24 h, followed by different doses of leuprolide for 48 h and, finally, single doses of radiation (3, 6, and 9 Gy). After radiation, cell survival, apoptosis, cell cycle distribution, and colony growth were evaluated. RESULTS: Radiation reduced cell survival and increased apoptosis in a dose-dependent manner. This effect was also directly related to leuprolide concentration. Pretreatment with IN3 enhanced apoptosis and decreased cell survival, also observing a higher proportion of cells arrested in G2. CONCLUSION: Neoadjuvant leuprolide increases radiation-mediated apoptosis of PCa cells. This effect was enhanced by pretreatment with pharmacoperone IN3. Clinical use of IN3 as a radiosensitizer combined with androgen deprivation therapy to improve survival of patients with PCa remains to be evaluated.

Neurobiology of puberty and its disorders.

Puberty, which in humans is considered to include both gonadarche and adrenarche, is the period of becoming capable of reproducing sexually and is recognized by maturation of the gonads and development of secondary sex characteristics. Gonadarche referring to growth and maturation of the gonads is fundamental to puberty since it encompasses increased gonadal steroid secretion and initiation of gametogenesis resulting from enhanced pituitary gonadotropin secretion, triggered in turn by robust pulsatile GnRH release from the hypothalamus. This chapter reviews the development of GnRH pulsatility from before birth until the onset of puberty. In humans, GnRH pulse generation is restrained during childhood and juvenile development. This prepubertal hiatus in hypothalamic activity is considered to result from a neurobiological brake imposed upon the GnRH pulse generator resident in the infundibular nucleus. Reactivation of the GnRH pulse generator initiates pubertal development. Current understanding of the genetics and physiology of the brake will be discussed, as will hypotheses proposed to account for timing the resurgence in pulsatile GnRH and initiation of puberty. The chapter ends with a discussion of disorders associated with precocious or delayed puberty with a focus on those with etiologies attributed to aberrant GnRH neuron anatomy or function. A pediatric approach to patients with pubertal disorders is provided and contemporary treatments for both precocious and delayed puberty outlined.

Association between GnRH Receptor Polymorphisms and Luteinizing Hormone Levels for Low Ovarian Reserve Infertile Women.

The choice of ovarian stimulation protocols in assisted reproduction technology (ART) cycles for low ovarian reserve patients is challenging. Our previous report indicated that the gonadotrophin-releasing (GnRH) agonist (GnRHa) protocol is better than the GnRH antagonist (GnRHant) protocol for young age poor responders. Here, we recruited 269 patients with anti-Müllerian hormone (AMH) < 1.2 ng/mL undergoing their first ART cycles for this nested case-control study. We investigated the genetic variants of the relevant genes, including follicular stimulating hormone receptor (FSHR; rs6166), AMH (rs10407022), GnRH (rs6185), and GnRH receptor (GnRHR; rs3756159) in patients <35 years (n = 86) and patients ≥35 years of age (n = 183). Only the genotype of GnRHR (rs3756159) is distributed differently in young (CC 39.5%, CT/TT 60.5%) versus advanced (CC 24.0%, CT/TT 76.0%) age groups (recessive model, p = 0.0091). Furthermore, the baseline luteinizing hormone (LH) levels (3.60 (2.45 to 5.40) vs. 4.40 (2.91 to 6.48)) are different between CC and CT/TT genotype of GnRHR (rs3756159). In conclusion, the genetic variants of GnRHR (rs3756159) could modulate the release of LH in the pituitary gland and might then affect the outcome of ovarian stimulation by GnRHant or GnRHa protocols for patients with low AMH levels.

Increased testosterone and proinflammatory cytokines in patients with polycystic ovary syndrome correlate with elevated GnRH receptor autoantibody activity assessed by a fluorescence resonance energy transfer-based bioassay.

PURPOSE: The recently identified agonistic autoantibodies (AAb) to the gonadotropin-releasing hormone receptor (GnRHR) are a novel investigative and therapeutic target for polycystic ovary syndrome (PCOS). In this study, we used a new cell-based fluorescence resonance energy transfer (FRET) bioassay to analyze serum GnRHR-AAb activity and examine its relationship with testosterone and proinflammatory cytokines in patients with PCOS. METHODS: Serum samples from 33 PCOS patients, 39 non-PCOS ovulatory infertile controls and 30 normal controls were tested for GnRHR-AAb activity and proinflammatory cytokines in a FRET-based bioassay and multiplex bead-based immunoassay, respectively. Correlation was analyzed using the Spearman's correlation test. RESULTS: Serum GnRHR-AAb activity was significantly higher in the PCOS patients than for the ovulatory infertile (p < 0.05) and normal (p < 0.01) controls. GnRHR-AAb were positive in 39% of PCOS patients, 10% of ovulatory infertile controls, and 0% of normal controls. PCOS IgG-induced GnRHR activation was specifically blocked by the GnRHR antagonist cetrorelix. Serum levels of proinflammatory cytokines interleukin-2, interleukin-6, interferon-γ, and tumor necrosis factor-α were significantly increased in PCOS patients compared with ovulatory infertile and normal controls (p < 0.01). Correlation analysis demonstrated positive correlations of GnRHR-AAb activity with testosterone and proinflammatory cytokine levels in the PCOS group. CONCLUSIONS: Elevated GnRHR-AAb activity, as assessed by a new FRET assay, is associated with increased testosterone and proinflammatory cytokines in PCOS, suggesting autoimmune activation of GnRHR may contribute to the pathogenesis of this common disorder.

Androgen receptor positively regulates gonadotropin-releasing hormone receptor in pituitary gonadotropes.

Within pituitary gonadotropes, the gonadotropin-releasing hormone receptor (GnRHR) receives hypothalamic input from GnRH neurons that is critical for reproduction. Previous studies have suggested that androgens may regulate GnRHR, although the mechanisms remain unknown. In this study, we demonstrated that androgens positively regulate Gnrhr mRNA in mice. We then investigated the effects of androgens and androgen receptor (AR) on Gnrhr promoter activity in immortalized mouse LßT2 cells, which represent mature gonadotropes. We found that AR positively regulates the Gnrhr proximal promoter, and that this effect requires a hormone response element (HRE) half site at -159/-153 relative to the transcription start site. We also identified nonconsensus, full-length HREs at -499/-484 and -159/-144, which are both positively regulated by androgens on a heterologous promoter. Furthermore, AR associates with the Gnrhr promoter in ChIP. Altogether, we report that GnRHR is positively regulated by androgens through recruitment of AR to the Gnrhr proximal promoter.

Transient suppression of ovulatory ovarian function in pony mares after treatment with slow-release deslorelin implants.

Behavior during the estrous cycle of mares can affect their performance and therefore inhibition of cyclical ovarian activity is indicated. We hypothesized that implants containing the GnRH analog deslorelin downregulate GnRH receptors and inhibit ovulation in mares. The estrous cycles of Shetland mares were synchronized with 2 injections of a PGF2α analog. One day after the second injection (day 0), mares received 9.4 (group D1, n = 6) and 4.7 mg deslorelin (D2, n = 5) as slow-release implants or 1.25 mg short-acting deslorelin as a control (C, n = 5). Ultrasonography of the reproductive tract and ovaries and observation of estrous behavior and collection of blood samples for analysis of progesterone and LH concentrations were performed every second day until day 10 and thereafter at 5-d intervals. Stimulation tests with the GnRH-agonist buserelin were performed on days 10 and 45. Until day 50, there were less spontaneous ovulations in group D1 (P < 0.01) and estrous behavior was reduced in groups D1 and D2 compared with group C (P < 0.05). The time until first ovulation (D1 62.0 ± 8.6, D2 44.2 ± 14.1, C 22.2 ± 3.1 d, P < 0.05) and the number of days with estrous behavior (P < 0.05) differed among groups. On day 10 after treatment, a GnRH stimulation test revealed interactions between group and time (P < 0.001) in plasma LH concentration that were no longer detectable on day 45 after treatment. In conclusion, long-acting deslorelin implants result in a transient downregulation of pituitary GnRH receptors that is associated with inhibition of ovulation and estrous behavior in Shetland mares.

A Clinician's Guide to the Treatment of Endometriosis with Elagolix.

Pain associated with endometriosis is a considerable burden for women, permeating all aspects of their lives, from their ability to perform daily activities to their quality of life. Although there are many options for endometriosis-associated pain management, they are often limited by insufficient efficacy, inconvenient routes of administration, and/or intolerable side effects. Elagolix, a nonpeptide, small-molecule gonadotropin-releasing hormone (GnRH) receptor antagonist, is the first new oral therapy to be approved for the treatment of endometriosis-associated pain in the United States in more than a decade. Modulation of estradiol with elagolix is dose dependent and ranges from partial to full suppression. Clinical evidence has shown that elagolix at both approved doses (150 mg once daily and 200 mg twice daily) is effective for reducing symptoms of pelvic pain (dysmenorrhea, nonmenstrual pelvic pain, and dyspareunia), improving quality of life, and decreasing use of rescue analgesics (nonsteroidal anti-inflammatory drugs and/or opioids). The availability of two dosing options allows for individualization of treatment based on baseline clinical factors and response to therapy. Elagolix is well tolerated, with less pronounced hypoestrogenic effects compared with GnRH agonists. This review provides an overview of elagolix, highlighting currently available treatment options and the application of this new treatment for women with endometriosis-associated pain.

The Role of GnRH Receptor Autoantibodies in Polycystic Ovary Syndrome.

OBJECTIVE: Is polycystic ovary syndrome (PCOS) associated with activating autoantibodies (AAb) to the second extracellular loop (ECL2) of gonadotropin-releasing hormone receptor (GnRHR)? DESIGN AND METHODS: We retrospectively screened sera from 40 patients with PCOS and 14 normal controls (NCs) with regular menses using enzyme-linked immunosorbent assay (ELISA) for the presence of GnRHR-ECL2-AAb. We obtained similar data from 40 non-PCOS ovulatory but infertile patients as a control group (OIC) of interest. We analyzed GnRHR-ECL2-AAb activity in purified immunoglobulin (Ig)G using a cell-based GnRHR bioassay. RESULTS: The mean ELISA value in the PCOS group was markedly higher than the NC (P = .000036) and the OIC (P = .0028) groups. IgG from a sample of 5 PCOS subjects, in contrast to a sample of 5 OIC subjects, demonstrated a dose-dependent increase in GnRHR-stimulating activity qualitatively similar to the acute action of the natural ligand GnRH and the synthetic agonist leuprolide. The GnRHR antagonist cetrorelix significantly suppressed (P < .01) the elevated GnRHR activity induced by IgG from 7 PCOS patients while the IgG activity level from 7 OIC subjects was unchanged. Five other OIC subjects had relatively high ELISA values at or above the 95% confidence limits. On further study, 3 had normal or low activity while 2 had elevated IgG-induced GnRHR activity. One suppressed with cetrorelix while the other did not. The copresence of PCOS IgG increased the responsiveness to GnRH and shifted the dosage response curve to the left (P < .01). CONCLUSIONS: GnRHR-ECL2-AAb are significantly elevated in patients with PCOS compared with NCs. Their presence raises important etiological, diagnostic, and therapeutic implications.

Molecular Identification, Characterization, and Expression Analysis of a Gonadotropin-Releasing Hormone Receptor (GnRH-R) in Pacific Abalone, Haliotis discus hannai.

A full-length cDNA sequence encoding a GnRH receptor was cloned from the pleuropedal ganglion of the Pacific abalone, Haliotis discus hannai. The cloned sequence is 1499-bp in length encoding a protein of 460 amino acid residues, with a molecular mass of 52.22 kDa and an isoelectric point (pI) of 9.57. The architecture of HdhGnRH-R gene exhibited key features of G protein-coupled receptors (GPCRs), including seven membrane spanning domains, putative N-linked glycosylation motifs, and phosphorylation sites of serine and threonine residues. It shared 63%, 52%, and 30% sequence identities with Octopus vulgaris, Limulus polyphemus, and Mizuhopecten yessoensis GnRH-R II sequences, respectively. Phylogenetic analysis indicated that HdhGnRH-R gene was clustered with GnRH-R II of O. vulgaris and O. bimaculoides. qPCR assay demonstrated that the mRNA expression level of this receptor was significantly higher in the pleuropedal ganglion than that in any other examined tissue. Transcriptional activities of this gene in gonadal tissues were significantly higher in the ripening stage. The mRNA expression of this gene was significantly higher in pleuropedal ganglion, testis, and ovary at higher effective accumulative temperature (1000 °C). In situ hybridization revealed that HdhGnRH-R mRNA was expressed in neurosecretory cells of pleuropedal ganglion. Our results suggest that HdhGnRH-R gene synthesized in the neural ganglia might be involved in the control of gonadal maturation and gametogenesis of H. discus hannai. This is the first report of GnRH-R in H. discus hannai and the results may contribute to further studies of GPCRs evolution or may useful for the development of aquaculture method of this abalone species.

Automated radiosynthesis and preclinical evaluation of Al[18F]F-NOTA-P-GnRH for PET imaging of GnRH receptor-positive tumors.

INTRODUCTION: Gonadotropin releasing hormone (GnRH) receptor is overexpressed in many human tumors. Previously we developed a 18F-labelled GnRH peptide. Although the GnRH-targeted PET probe can be clearly visualized by microPET imaging in a PC-3 xenograft model, clinical applications of the probe have been limited by complex labeling procedures, poor radiochemical yield, and unwanted accumulation in GnRH receptor negative tissues. In this study, we have designed a new 18F-labelled GnRH peptide that is more amenable to clinical development. METHODS: GnRH peptide analogues NOTA-P-GnRH was synthesized and automated radiolabeled with 18F using a Al[18F]F complex on a modified PET-MF-2V-IT-I synthesis module. The GnRH receptor affinities of AlF-NOTA-P-GnRH and NOTA-P-GnRH were determined by in vitro competitive binding assay. For in vitro characterization determination of stability and partition coefficients were carried out, respectively. Dynamic microPET and biodistribution studies of Al[18F]F-NOTA-P-GnRH were evaluated in xenograft tumor mouse models. RESULTS: The total radiochemical synthesis and purification of Al[18F]F-NOTA-P-GnRH was completed within 35 min with a decay-corrected yield of 35 ± 10%. The logP value of Al[18F]F-NOTA-P-GnRH was -2.74 ± 0.04 and the tracer was stable in phosphate-buffered saline, and bovine and human serum. The IC50 values of AlF-NOTA-P-GnRH and NOTA-P-GnRH were 116 nM and 56.2 nM, respectively. Dynamic PET imaging together with ex vivo biodistribution analyses revealed that Al[18F]F-NOTA-P-GnRH was clearly delineated in both PC-3 and MDA-MB-231 xenografted tumors. CONCLUSION: Al[18F]F-NOTA-P-GnRH can be efficiently produced on a commercially available automated synthesis module and has potential for use in clinical diagnosis of GnRH receptor-positive tumors. ADVANCES IN KNOWLEDGE: Our studies developed the automated radiosynthesis of a new 18F-labelled GnRH tracer and preclinical evaluation for future clinical application. IMPLICATIONS FOR PATIENT CARE: Quantitative and noninvasive imaging of GnRH expression would provide information for diagnosis and treatment of cancer patients.