GnRH Expression Research Articles

GnRH protective effects against amyloid β-induced cognitive decline: A potential role of the 17β-estradiol

IntroductionThe 17β-estradiol (E2) enhances hippocampal dendritic spine synapses, facilitates learning processes, and exerts neuroprotection. Brain estrogen decline has been reported in Alzheimer's disease. The role of GnRH in modulating steroid biosynthesis convinced us to examine whether hippocampal GnRH administration could enhance the local E2 levels and overcome the development of cognition decline in amyloid β (Aβ) neurotoxicity. To explore if GnRH acts through regulating E2 synthesis, letrozole, an aromatase inhibitor, has been applied in combination with GnRH. MethodsFemale rats received an intracerebroventricular injection of Aβ. The GnRH and, or letrozole were injected into the CA1 for 14 consecutive days. Working memory, novel object recognition memory, and anxiety-like behavior were evaluated. Serum and hippocampal E2 levels were measured. Hippocampal mRNA expression of GnRH (GnRH-R) and E2 (ERα and ERβ) receptors was assessed. GnRH effect on the excitability of pyramidal cells was studied by in vivo single-unit recording. ResultsGnRH increased hippocampal E2 levels, evoked an increase in the spontaneous firing of pyramidal neurons, and caused mRNA overexpression of hippocampal GnRH receptors. GnRH prevented the adverse effects of Aβ on working memory, NOR index, and anxiogenic behavior. Letrozole did not reverse GnRH modulatory effects on hippocampal E2 levels and neuroprotection. ConclusionGnRH prevented the Aβ-induced memory deficit, which may be mediated through hippocampal E2 levels enhancement. The electrophysiological analysis revealed the enhanced neuronal excitability in the CA1 region. All these data suggest that GnRH might be a promising candidate that reduces anxiety and improves memory indices in the context of Aβ neurotoxicity.

Mitochondrial dysfunction in GnRH neurons impaired GnRH production

The onset establishment and maintenance of gonadotropin-releasing hormone (GnRH) secretion is an important phenomenon regulating pubertal development and reproduction. GnRH neurons as well as other neurons in the hypothalamus have high-energy demands and require a constant energy supply from their mitochondria machinery to maintain active functioning. However, the involvement of mitochondrial function in GnRH neurons is still unclear. In this study, we examined the role of NADH Dehydrogenase (Ubiquinone) Fe–S protein 4 (Ndufs4), a member of the mitochondrial complex 1, on GnRH neurons using Ndufs4-KO mice and Ndufs4-KO GT1-7 cells. Ndufs4 was highly expressed in GnRH neurons in the medial preoptic area (MPOA) and NPY/AgRP and POMC neurons in the arcuate (ARC) nucleus in WT mice. Conversely, there was a significant decrease in GnRH expression in MPOA and median eminence of Ndufs4-KO mice, followed by impaired peripheral endocrine system. In Ndufs4-KO GT1-7 cells, Gnrh1 expression was significantly decreased with or without stimulation with either kisspeptin or NGF, whereas, stimulation significantly increased Gnrh1 expression in control cells. In contrast, there was no difference in cell signaling activity including ERK and CREB as well as the expression of GPR54, TrkA and p75NTR, suggesting that Ndufs4 is involved in the transcriptional regulation system for GnRH production. These findings may be useful in understanding the mitochondrial function in GnRH neuron.

Editorial introductions

Editorial introductions

The sex-specific patterns of changes in hypothalamic-pituitary-gonadal axis during experimental autoimmune encephalomyelitis

Multiple sclerosis develops during reproductive years in a sex-specific manner. Various neuroendocrine changes have been described in this inflammatory, demyelinating, and debilitating disease. We here aimed to determine the extent and sex specificity of alterations in the hypothalamic-pituitary-gonadal axis in the rat model of multiple sclerosis named experimental autoimmune encephalomyelitis. During the disease course, the hypothalamic tissue showed transient upregulation of inflammatory marker genes Gfap, Cd68, Ccl2, and Il1b in both sexes, but accompanied by sex-specific downregulation of Kiss1 (in females only) and Gnrh1 (in males only) expression. In females, the expression of gonadotrope-specific genes Lhb, Cga, and Gnrhr was also inhibited, accompanied by decreased basal but not stimulated serum luteinizing hormone levels and a transient arrest of the estrous cycle. In contrast, Fshb expression and serum progesterone levels were transiently elevated, findings consistent with the maintenance of the corpora lutea, and elevated immunohistochemical labeling of ovarian StAR, a rate limiting protein in steroidogenic pathway. In males, downregulation of Gnrhr expression and basal and stimulated serum luteinizing hormone and testosterone levels were accompanied by inhibited testicular StAR protein expression. We propose that inflammation of hypothalamic tissue downregulates Kiss1 and Gnrh1 expression in females and males, respectively, leading to sex-specific changes downstream the axis.

Effects of leptin on HPG axis and reproductive function in male rat in simulated altitude of 5500 m hypoxia environment

High altitude hypobaric hypoxia environment impairs male’s reproductive function. Leptin is an adipose tissue-derived hormone which regulates body weight homeostasis. Its receptor (LepR) has been found in all levels of male reproductive axis, indicating that it can affect male reproductive system in a direct or (and) indirect way. However, the role of leptin signaling in hypobaric hypoxia induced male reproductive dysfunction remains to be elucidated. In this study, we investigated the changes of leptin levels in male SD rats in stimulated altitude of 5500 m hypobaric hypoxia environment and their effects on the hypothalamus-pituitary-gonad axis (HPG axis). A hypoxia animal model was established using a hypobaric hypoxia chamber. Rats were divided randomly into 1, 7, 14, 28-day hypoxia group, recovery group (14 days hypoxia+14 days normoxia) and their control groups. Hypoxia groups displayed obvious changes of testicular and epididymis index compared to control groups. The total number of sperm and sperm motility rate decreased dramatically, while sperm deformity rate increased in hypoxia groups. The flow cytometry analysis showed that the percentage of haploid in 1-day, 7-day and 28-day hypoxia groups increased while the proportion of diploid decreased in 14-day and 28-day hypoxia group. TUNEL staining showed that the testis cells apoptosis index (AI) of hypoxia groups increased significantly, and the apoptosis of cells mainly focus on spermatogonia and spermatocytes. The expression of GnRH in hypothalamus decreased dramatically under hypoxia condition, accompanied with the reduction of serum testosterone (T) level in 1-day and 28-day hypoxia groups and free-testosterone level (FT) in 1-day and 14-day hypoxia groups. Importantly, ELISA analysis showed that serum leptin level decreased in 7-day hypoxia groups and acylated-ghrelin, gastrin also changed, accompanying with reduction of LepR in hypothalamus in hypoxia groups. Immunohistochemical staining exhibited increased leptin and LepR in testis under hypobaric hypoxia conditions. Our results suggested that simulated high altitude hypobaric hypoxia environment decreased male reproductive function, depressed HPG axis activity and altered the serum concentration of hormones related to food intake in adult male rats. Additionally, hypobaric hypoxia induced the leptin-LepR expression in adult male rats’ testis, suggesting leptin-LepR signaling may mediate hypoxia-induced impairment in male rats’ reproductive system.

Central injection of neuropeptide Y modulates sexual behavior in male rats: interaction with GnRH and kisspeptin/neurokinin B/dynorphin

Aims A number of studies have shown that neuropeptide Y (NPY) is considered to be one of the key regulators of hypothalamic-pituitary-gonadal (HPG) axis in the mammals. In addition, kisspeptin (encode by Kiss1 gene), neurokinin B (encode by Tac3 gene) and dynorphin (encode by Pdyn gene) (commonly known as KNDy secreting neurons) are a powerful upstream regulators of GnRH neuron in hypothalamus. Materials and Methods The present study aims to investigate the effects of the intracerebroventricular (icv) injection of NPY and BIBP3226 (NPY receptor antagonist (NPYRA)) on the male sexual behavioral. Additionally, in order to see whether NPY signals can be relayed through the pathway of kisspeptin/neurokinin B/dynorphin, the gene expression of these peptides along with Gnrh1 gene in the hypothalamus were measured. Results The icv injection of NPY decreased the latencies and increase the frequencies of sexual parameters of the male rats in a significant way. In this line, NPYRA antagonized the stimulative effects of NPY. Moreover, data from real-time quantitative PCR indicated that injection of NPY significantly increased the gene expression of Gnrh1, Kiss1 and Tac3 and decrease the Pdyn while treatment with NPYRA controlled the modulative effects of NPY on these gene expression. Conclusions In conclusion based on the results of this study, NPY can exert its impacts on the sexual behavior of male rats via modulation of the KNDy secreting neurons as an interneural pathway to GnRH neurons.

Maternal Exposure to T-2 Toxin Affects Puberty Genes and Delays Estrus Cycle in Mice Offspring.

Simple SummaryThe experiment was designed to investigate the effect of gestational and lactational exposure to the T-2 toxin and its effects on the puberty of female mice offspring. T-2 toxin contaminates feed participates in the maternal diet. It directly interferes with the normal physiological function of offspring because the maternal diet is the most important during pregnancy and lactation. Female mice are more sensitive to the maternal diet during the lactation stage. Thus, their maturity stage is very complex and regulated by the hypothalamus, which controls Gonadotropin-releasing hormone (GnRH), and it also secretes reproductive hormones. Current findings report that T-2 toxins during late gestation and lactation period directly affect offspring, disturb the vaginal environment, delayed normal estrus cycle, and puberty age induces oxidative stress-caused ovarian damage. Based on findings, we think it is necessary to raise people’s attention to T-2 toxin-contaminated feed offered to animals. Current results reveal information about the health risks associated with a maternal diet, which affects the next generation.Among foodborne toxicities, the T-2 toxin is the most toxic member of trichothecenes mycotoxins, which has been shown to impair the development and reproductive efficiency of animals. Pups are particularly more quickly prone to programming the effects of the maternal diet during the gestational and lactation periods. Few studies have reported the maternal toxic effect on the next generation. Dams were served the T-2 toxin at a dose of 0.005 and 0.05 mg/kg body weight/day and control group 0 mg/kg from gestation day 14 to lactation day 21. Female mice offspring were selected at the weaning age. Our observations indicate that age during the vaginal opening and di-estrus stage increased and the length of the estrus cycle, first di-estrus, and regular estrus cycling were delayed with prolonged di-estrus in the 0.05 mg/kg group compared to the 0.005 mg/kg and control group. Transcription level analysis showed that mice at a dose of 0.05 mg/kg exhibited a decrease in hypothalamic mRNA expression of Gnrh and Gnrhr, Lhb, and Fshb in the pituitary gland, with a significant decrease of Fshr and Lhr in the ovaries. Present findings report that postnatal exposure to the T-2 toxin delayed puberty age in female mice and induced oxidative stress, ovarian damage, and reduced vaginal epithelium wall majorly in the 0.05 mg/kg group, and showed fewer effects in the 0.005 mg/kg group.

Annual patterns of ocular melatonin level in the female grass puffer, Takifugu alboplumbeus: possible involvement in seasonal reproductive response.

The aim of this study was to investigate the expression patterns of ocular melatonin in the annual reproductive cycle of the female grass puffer. Spawning season of the female grass puffer is from June to July in Jeju, South Korea. Time-resolved fluoroimmunoassay revealed that levels of ocular melatonin, which show an annual change, peaked in May (spawning season). Additionally, expression of reproductive-related genes also showed annual patterns: GnRH1 peaked in August, GnRH2 peaked in February, GnRH3, Kiss2, and LPXRFa peaked in November. These results suggest that ocular melatonin may be related to the annual reproductive cycle in the grass puffer. To better understand the photic regulation of AANAT1a mRNA in the retina, we observed the nocturnal pattern of ocular melatonin levels daily, which shows a nocturnal pattern in both short photoperiod (SD) and long photoperiod (LD) conditions. In the brain, AANAT2 mRNA also shows a nocturnal pattern in both SD and LD; however, the time of peak expression of AANAT2 mRNA was unchanged in both conditions. Following intraperitoneal injection of melatonin for 2weeks, expression of GnRH2 and LPXRFa mRNA in the brain significantly increased, while that of Kiss2 mRNA was decreased, suggesting that melatonin has a reproduction-related effect. Furthermore, under SD and LD conditions for 14weeks, the gonadosomatic index more increased and the maturity of the ovary progressed under LD compared with those under SD, suggesting that the SD photoperiodic signal inactivated ovarian development. These results indicate that the ocular melatonin may have a possible role in the reproductive endocrinology of the grass puffer.

Neonatal exposure to bisphenol A advances pubertal development in female rats

Neonatal exposure to bisphenol A (BPA) is hypothesized to advance pubertal development. However, the effects of neonatal BPA exposure on pubertal development has not been described. In this study, female Sprague-Dawley rats were exposed to 0.05, 0.5, 5, or 10 mg·kg-1 ·day-1 BPA, or corn oil vehicle alone from postnatal day 1 (PND1) to PND10 via subcutaneous injection. We evaluated day of vaginal opening (DVO), ovarian morphology, serum hormone concentrations, and hypothalamic expression of Gnrh1 and Kiss1 in female rats at PND35. DVO was significantly advanced in rats exposed to 5 and 10 mg·kg-1 ·day-1 BPA. Serum hormone concentrations increased as BPA dose increased. Additionally, hypothalamic Gnrh1 and Kiss1 expression were increased with BPA exposure; rats exposed to 10 mg·kg-1 ·day-1 BPA had significantly upregulated hypothalamic Gnrh1 and Kiss1 expressions in terms of both messenger RNA and protein levels. Our results suggest that exposure to a 10 mg·kg-1 ·day-1 dose of BPA might advance pubertal development significantly. In addition, within the range of 0 to 10 mg·kg-1 ·day-1 , neonatal exposure to BPA may affect pubertal development in a dose-dependent manner.

Estradiol Potentiates But Is Not Essential for Prolactin-Induced Suppression of Luteinizing Hormone Pulses in Female Rats.

Hyperprolactinemia causes infertility by suppressing gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion. Because effects of prolactin (PRL) on the hypothalamus usually require estradiol (E2), we investigated the role of E2 in PRL-induced suppression of LH pulses. Ovariectomized (OVX) rats treated with oil or E2 (OVX + E2) received a subcutaneous injection of ovine PRL (oPRL) 30 minutes before serial measurement of LH in the tail blood by enzyme-linked immunosorbent assay. E2 reduced pulsatile LH secretion. oPRL at 1.5 mg/kg further reduced LH pulse frequency in OVX + E2 but had no effect in OVX rats. The higher dose of 6-mg/kg oPRL decreased LH pulse frequency in both OVX and OVX + E2 rats, whereas pulse amplitude and mean LH levels were lowered only in OVX + E2 rats. Kisspeptin immunoreactivity and Kiss1 messenger ribonucleic acid (mRNA) levels were decreased in the arcuate nucleus (ARC) of OVX + E2 rats. oPRL decreased both kisspeptin peptide and gene expression in the ARC of OVX rats but did not alter the already low levels in OVX + E2 rats. In the anteroventral periventricular nucleus, oPRL did not change kisspeptin immunoreactivity and, paradoxically, increased Kiss1 mRNA only in OVX + E2 rats. Moreover, oPRL effectively reduced Gnrh expression regardless of E2 treatment. In this study we used tail-tip blood sampling to determine the acute effect of PRL on LH pulsatility in female rats. Our findings characterize the role of E2 in the PRL modulation of hypothalamic components of the gonadal axis and LH release, demonstrating that E2 potentiates but is not essential for the suppression of pulsatile LH secretion caused by hyperprolactinemia.

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

IntroductionGonadotropin 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. MethodsGnRH 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. ResultsThe 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. ConclusionAl[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 knowledgeOur studies developed the automated radiosynthesis of a new 18F-labelled GnRH tracer and preclinical evaluation for future clinical application. Implications for patient careQuantitative and noninvasive imaging of GnRH expression would provide information for diagnosis and treatment of cancer patients.

The mRNA expression patterns of kisspeptins, GnRHs, and gonadotropins in the brain and pituitary gland of a tropical damselfish, Chrysiptera cyanea, during the reproductive cycle.

The sapphire devil (Chrysiptera cyanea) is a tropical damselfish that undergoes active reproduction under long-day conditions. To elucidate the physiological regulation of the brain-pituitary-gonadal axis in female sapphire devil, we cloned and characterized the genes of two kisspeptins (kiss1 and kiss2), three gonadotropin-releasing hormones (gnrh1, gnrh2, gnrh3), and the β-subunit of two gonadotropins (fshβ and lhβ) and investigated the gene expression changes during ovarian development. Quantitative polymerase chain reaction analyses in various brain parts revealed high expression levels of kiss1, kiss2, and gnrh2 in the diencephalon; gnrh2 and gnrh3 in the telencephalon; and fshβ and lhβ in the pituitary. In situ hybridization (ISH) analyses revealed positive signals of kiss1 in the dorsal and ventral habenular nucleus and of kiss2 in the dorsal and ventral parts of the nucleus of the lateral recess. This analysis showed gnrh1 expression in the preoptic area (POA), suggesting that GnRH1 plays a stimulating role in the secretion of gonadotropins from the pituitary of the sapphire devil. High transcription levels of kiss1, kiss2, gnrh1, gnrh2, fshβ, and lhβ were observed in the brain during the late vitellogenic stage, suggesting their involvement in the physiological processes of vitellogenesis. Immersion of fish in estradiol-17β (E2)-containing seawater resulted in increased expression of kiss2 and gnrh1 in their brains. This study showed that kiss-expressing neurons in the diencephalon are influenced by E2, leading to upregulation of gnrh1 in the POA and of fshβ and lhβ in the pituitary during vitellogenesis.

Expression of the kisspeptin/gonadotropin-releasing hormone (GnRH) system in the brain of female Chinese sucker (Myxocyprinus asiaticus) at the onset of puberty.

The kisspeptin-kisspeptin receptor (kissr)-gonadotropin-releasing hormone (GnRH) system plays a key role in regulating the onset of puberty in mammals. However, the role of this system in fish is still unclear. We examined the relative gene expression patterns for kiss1, kiss2, kissr2, sGnRH, and pjGnRH in all parts of the brains of Chinese sucker (Myxocyprinus asiaticus) females at the prepubertal and pubertal stages by using real-time PCR. We also analyzed the expression of kiss1 and GnRH1 via immunofluorescence. Two variants of kisspeptin; a variant of kissr (kissr2); and two variants of GnRH, pjGnRH (GnRH1), and sGnRH (GnRH3), were expressed in all parts of the brain. The mRNA expression of kiss1 was higher in the telencephalon, mesencephalon, and diencephalon at the pubertal stage than at the prepubertal stage, and the expression of kiss2 was higher in only the telencephalon. The expression of kissr2 was higher in all parts of the brain, except the medulla, at the pubertal stage than at the prepubertal stage. pjGnRH was highly expressed in all parts of the brain at the pubertal stage, whereas sGnRH expression showed no distinct changes, except in the epencephalon. Strong kiss1 and weak GnRH-1 immunoreactivity was observed in the pineal gland, lateral tuberal nucleus (NLT), and ventral part of the NLT in the diencephalon of the Chinese sucker females at the pubertal stage. Our results suggest that the kiss1-kissr2-pjGnRH system was expressed highly at the onset of pubertal female Chinese sucker.

Amh regulate female folliculogenesis and fertility in a dose-dependent manner through Amhr2 in Nile tilapia

In the present study, Amh was found to be abundantly expressed in the granulosa cells of the primary growth follicles, and Amhr2 in the granulosa cells, oogonia and phase I oocytes in tilapia by immunohistochemistry. In addition, Amh and Amhr2 were also found to be expressed in the brain and pituitary. Heterozygous mutation of either amh or amhr2 resulted in increased primary growth follicles and decreased fertility, and homozygous mutation resulted in hypertrophic ovaries with significantly increased primary follicles and failed transition from primary to vitellogenic follicles. Expression of gnrh3 in the brain, fsh and lh in the pituitary and serum E2 concentration were significantly decreased in both mutants. Significantly increased apoptosis of follicle cells was observed in both mutants. However, administration of E2 failed to rescue the folliculogenesis defects of the mutants. Our results suggested that Amh acts in a dose-dependent manner by binding Amhr2 in tilapia.

Changes in expression of reproduction-related hormones in the brain and pituitary during early ovarian differentiation and development in the red spotted grouper Epinephelus akaara, with emphasis on FSHβ and LHβ

The brain-pituitary-gonadal (BPG) axis, an important endocrine system, is closely related to gonadal development in teleosts. This study aimed to investigate the regulation of reproduction-related hormones in the BPG axis during early ovarian differentiation and development from 30 to 160 days post hatching (dph) in the red spotted grouper. The immune signals of FSHβ and LHβ were detected by immunohistochemistry. kiss1, kiss2, gpr54, gnrh1, fshβ, and lhβ gene expression was analyzed using qRT-PCR. 17β-estradiol (E2) levels were analyzed by ELISA. The immune signals of FSHβ and LHβ were detected in the central, ventral, or marginal part of the proximal pars distalis area at 55, 80, 100, 120, and 160 dph, along with a few signals detected in the external border of the pars intermedia area at 55, 120, and 160 dph. As a result of histological observation, we determined that ovarian differentiation began at 80 dph and finished at 120 dph. At 30 dph before ovarian differentiation, only the FSHβ signal was detected but with weak reaction, suggesting the earlier appearance of FSHβ than LHβ after hatching. Comparison of the signal intensity and gene expression of FSHβ and LHβ indicated that LH had stronger signals and higher transcript levels at 80 dph while E2 levels also increased, suggesting that LH may play a more active role in the onset of ovarian differentiation. gnrh1 and the kisspeptin genes showed no clear changes, but gpr54 (kisspeptin receptor) significantly increased during the ovarian differentiation phase. These results suggest that the kisspeptin receptor GPR54 may be involved in ovarian differentiation in the red spotted grouper.

MiR-29 family regulates the puberty onset mediated by a novel Gnrh1 transcription factor TBX21.

Gonadotropin-releasing hormone (GnRH) is the ultimate signal by which the neuroendocrine system controls the puberty onset and fertility in mammals. The pulsatile release of GnRH is regulated by numerous extracellular and intracellular factors, including miRNAs. Here, we report a novel regulation mechanism mediated by miR-29 family. We found that the absence of miR-29s resulted in elevated expression of Gnrh1 in GT1-7 cells. Through in silico and wet analysis, we identified Tbx21, a target gene of miR-29, as the main effector. As a transcription activator, TBX21 stimulates the expression of Gnrh1 directly by binding to its promoter region, and indirectly by activating the expression of Dlx1, another transcription activator of Gnrh1. Stereotactic brain infusion of miR-29 inhibitor into the hypothalamus caused earlier puberty onset in prepubertal female mice than that of intact controls. The female mice with ectopic expression of Tbx21 in the hypothalamus were affected in both puberty onset and fertility, as they had higher level of serum LH and FSH, larger litter size but steeper decline of fertility compared with those of controls. Our results revealed that miR-29-3p and its target Tbx21 played a role in regulating the mammalian puberty onset and reproduction by modulating the Gnrh1 expression.

The capability of L-carnitine-mediated antioxidant on cock during aging: evidence for the improved semen quality and enhanced testicular expressions of GnRH1, GnRHR, and melatonin receptors MT 1/2.

Precise natural anti-oxidative compounds have facilitated the research of infertile gametes and the development of novel bio-therapeutics, especially the molecules that are based on the reduction of oxidative stress, such as L-carnitine (LC). In addition to, the defect in the functioning of sperm mitochondrial and the decreasing seminal antioxidant ability due to aging, its essential role in permitting the mitochondrial import and oxidation of long chain fatty acids is worthy. Therefore, current study was designed to investigate the effects of dietary LC on semen quality, seminal antioxidant activity, and their implications for the fertility in aged cocks for 12 wk. Supplementation of the feed with two different doses of LC (50 and 150mg/kg body weight/day) for 12 wk showed significantly increased in the reproductive activity of cock, in comparison to the control group. Seminal analysis showed that supplementation of LC significantly increased (P < 0.05) the sperm motility, concentration, livability, semen quality factor, seminal malondialdehyde concentration, catalase, and glutathione peroxidase activities. In addition, addition of LC significantly increased (P < 0.05) the plasma concentration of testosterone and prostaglandin E2 but posed no significant effect on the concentration of follicle-stimulating hormone. Furthermore, the findings of artificial insemination showed significant increased (P < 0.05) in the percentage of fertility in LC groups, while the percentage hatchability and mortality remained unchanged. Immunohistochemistry analysis revealed that LC significantly increased (P < 0.05) the testicular immunopositivity of MT1 and MT2. Moreover, the administration of LC to the aged cocks enhanced (P < 0.05) GnRH1 and GnRHR mRNA levels when compared with untreated cocks. The results of the present study suggest that LC treatment of aged cocks increases the seminal antioxidant enzymes and sexual hormones levels, which may improve the semen quality by increasing the expression of GnRH1 and melatonin receptors (MT1 and MT2) activities. Collectively, LC could be a suitable feed supplementation to increase reproductive activities through enhancing semen quality in aging cocks.

Genome-wide Analysis of Common Copy Number Variation and Epithelial Ovarian Cancer Risk.

Germline DNA copy number variation (CNV) is a ubiquitous source of genetic variation and remains largely unexplored in association with epithelial ovarian cancer (EOC) risk. CNV was quantified in the DNA of approximately 3,500 cases and controls genotyped with the Illumina 610k and HumanOmni2.5M arrays. We performed a genome-wide association study of common (>1%) CNV regions (CNVRs) with EOC and high-grade serous (HGSOC) risk and, using The Cancer Genome Atlas (TCGA), performed in silico analyses of tumor-gene expression. Three CNVRs were associated (P < 0.01) with EOC risk: two large (∼100 kb) regions within the 610k set and one small (<5 kb) region with the higher resolution 2.5M data. Large CNVRs included a duplication at LILRA6 (OR = 2.57; P = 0.001) and a deletion at CYP2A7 (OR = 1.90; P = 0.007) that were strongly associated with HGSOC risk (OR = 3.02; P = 8.98 × 10-5). Somatic CYP2A7 alterations correlated with EGLN2 expression in tumors (P = 2.94 × 10-47). An intronic ERBB4/HER4 deletion was associated with reduced EOC risk (OR = 0.33; P = 9.5 × 10-2), and somatic deletions correlated with ERBB4 downregulation (P = 7.05 × 10-5). Five CNVRs were associated with HGSOC, including two reduced-risk deletions: one at 1p36.33 (OR = 0.28; P = 0.001) that correlated with lower CDKIIA expression in TCGA tumors (P = 2.7 × 10-7), and another at 8p21.2 (OR = 0.52; P = 0.002) that was present somatically where it correlated with lower GNRH1 expression (P = 5.9 × 10-5). Though CNV appears to not contribute largely to EOC susceptibility, a number of low-to-common frequency variants may influence the risk of EOC and tumor-gene expression. Further research on CNV and EOC susceptibility is warranted, particularly with CNVs estimated from high-density arrays.

Deletion of the Homeodomain Protein Six6 From GnRH Neurons Decreases GnRH Gene Expression, Resulting in Infertility.

Hypothalamic GnRH (luteinizing hormone-releasing hormone) neurons are crucial for the hypothalamic-pituitary-gonadal (HPG) axis, which regulates mammalian fertility. Insufficient GnRH disrupts the HPG axis and is often associated with the genetic condition idiopathic hypogonadotropic hypogonadism (IHH). The homeodomain protein sine oculis-related homeobox 6 (Six6) is required for the development of GnRH neurons. Although it is known that Six6 is specifically expressed within a more mature GnRH neuronal cell line and that overexpression of Six6 induces GnRH transcription in these cells, the direct role of Six6 within the GnRH neuron in vivo is unknown. Here we find that global Six6 knockout (KO) embryos show apoptosis of GnRH neurons beginning at embryonic day 14.5 with 90% loss of GnRH neurons by postnatal day 1. We sought to determine whether the hypogonadism and infertility reported in the Six6KO mice are generated via actions within the GnRH neuron in vivo by creating a Six6-flox mouse and crossing it with the LHRHcre mouse. Loss of Six6 specifically within the GnRH neuron abolished GnRH expression in ∼0% of GnRH neurons. We further demonstrated that deletion of Six6 only within the GnRH neuron leads to infertility, hypogonadism, hypogonadotropism, and delayed puberty. We conclude that Six6 plays distinct roles in maintaining fertility in the GnRH neuron vs in the migratory environment of the GnRH neuron by maintaining expression of GnRH and survival of GnRH neurons, respectively. These results increase knowledge of the role of Six6 in the brain and may offer insight into the mechanism of IHH.

Irisin in the primate hypothalamus and its effect on GnRH in vitro.

Irisin, encoded by the FNDC5 gene, is a recently discovered endocrine factor mainly secreted as a myokine and adipokine. However, irisin/FNDC5 expression has also been reported in different other organs including components of the reproductive axis. Yet, there is the scarcity of data on FNDC5/irisin expression, regulation and its reproductive effects, particularly in primates. Here, we report the expression of FNDC5/irisin, along with PGC1A (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and ERRA (estrogen-related receptor alpha), in components of the reproductive axis of marmoset monkeys. Hypothalamic FNDC5 and ERRA transcript levels are developmentally regulated in both male and female. We further uncovered sex-specific differences in FNDC5, ERRA and PGC1A expression in muscle and the reproductive axis. Moreover, irisin and ERRα co-localize in the marmoset hypothalamus. Additionally, in the arcuate nucleus of rhesus monkeys, the number of irisin+ cells was significantly increased in short-term fasted monkeys as compared to ad libitum-fed monkeys. More importantly, we observed putative interaction of irisin-immunoreactive fibers and few GnRH-immunoreactive cell bodies in the mediobasal hypothalamus of the rhesus monkeys. Functionally, we noted a stimulatory effect of irisin on GnRH synthesis and release in mouse hypothalamic neuronal GT1-7 cells. In summary, our findings show that FNDC5 and irisin are developmentally, metabolic-status dependently and sex-specifically expressed in the primate hypothalamic-pituitary-gonadal axis and exert a stimulatory effect on GnRH expression and release in mouse hypothalamic cells. Further studies are required to confirm the reproductive effects of irisin in vivo and to illuminate the mechanisms of its regulation.