A Role for Kisspeptins in the Regulation of Gonadotropin Secretion in the Mouse
TL;DR: Kisspeptins are products of the KiSS-1 gene, which bind to a G protein-coupled receptor known as GPR54, and it is concluded that kisspeptin-GPR54 signaling may be part of the hypothalamus circuitry that governs the hypothalamic secretion of GnRH.
Abstract: Kisspeptins are products of the KiSS-1 gene, which bind to a G protein-coupled receptor known as GPR54. Mutations or targeted disruptions in the GPR54 gene cause hypogonadotropic hypogonadism in humans and mice, suggesting that kisspeptin signaling may be important for the regulation of gonadotropin secretion. To examine the effects of kisspeptin-54 (metastin) and kisspeptin-10 (the biologically active C-terminal decapeptide) on gonadotropin secretion in the mouse, we administered the kisspeptins directly into the lateral cerebral ventricle of the brain and demonstrated that both peptides stimulate LH secretion. Further characterization of kisspeptin-54 demonstrated that it stimulated both LH and FSH secretion, at doses as low as 1 fmol; moreover, this effect was shown to be blocked by pretreatment with acyline, a potent GnRH antagonist. To learn more about the functional anatomy of kisspeptins, we mapped the distribution of KiSS-1 mRNA in the hypothalamus. We observed that KiSS-1 mRNA is expressed in areas of the hypothalamus implicated in the neuroendocrine regulation of gonadotropin secretion, including the anteroventral periventricular nucleus, the periventricular nucleus, and the arcuate nucleus. We conclude that kisspeptin-GPR54 signaling may be part of the hypothalamic circuitry that governs the hypothalamic secretion of GnRH.
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TL;DR: GPR54 is defined as a major control point in the reproductive axis and kisspeptin is suggested to be a neurohormonal effector, demonstrating that a key action ofkisspeptin on the hypothalamo-pituitary-gonadal axis occurs directly at the level of GnRH release.
Abstract: We have recently described a molecular gatekeeper of the hypothalamic-pituitary-gonadal axis with the observation that G protein-coupled receptor 54 (GPR54) is required in mice and men for the pubertal onset of pulsatile luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion to occur. In the present study, we investigate the possible central mode of action of GPR54 and kisspeptin ligand. First, we show that GPR54 transcripts are colocalized with gonadotropin-releasing hormone (GnRH) neurons in the mouse hypothalamus, suggesting that kisspeptin, the GPR54 ligand, may act directly on these neurons. Next, we show that GnRH neurons seem anatomically normal in gpr54–/– mice, and that they show projections to the median eminence, which demonstrates that the hypogonadism in gpr54–/– mice is not due to an abnormal migration of GnRH neurons (as occurs with KAL1 mutations), but that it is more likely due to a lack of GnRH release or absence of GnRH neuron stimulation. We also show that levels of kisspeptin injected i.p., which stimulate robust LH and FSH release in wild-type mice, have no effect in gpr54–/– mice, and therefore that kisspeptin acts directly and uniquely by means of GPR54 signaling for this function. Finally, we demonstrate by direct measurement, that the central administration of kisspeptin intracerebroventricularly in sheep produces a dramatic release of GnRH into the cerebrospinal fluid, with a parallel rise in serum LH, demonstrating that a key action of kisspeptin on the hypothalamo-pituitary-gonadal axis occurs directly at the level of GnRH release. The localization and GnRH release effects of kisspeptin thus define GPR54 as a major control point in the reproductive axis and suggest kisspeptin to be a neurohormonal effector.
1,129 citations
TL;DR: In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.
Abstract: Heterotrimeric G proteins are key players in transmembrane signaling by coupling a huge variety of receptors to channel proteins, enzymes, and other effector molecules. Multiple subforms of G proteins together with receptors, effectors, and various regulatory proteins represent the components of a highly versatile signal transduction system. G protein-mediated signaling is employed by virtually all cells in the mammalian organism and is centrally involved in diverse physiological functions such as perception of sensory information, modulation of synaptic transmission, hormone release and actions, regulation of cell contraction and migration, or cell growth and differentiation. In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.
1,074 citations
Cites background from "A Role for Kisspeptins in the Regul..."
...Kisspeptins for example, a family of peptides derived from the metastasis suppressor gene Kiss-1, were shown to enhance hypothalamic gonadotropin-releasing hormone secretion via the GPR54 receptor (137, 220, 472), and genetic inactivation of GPR54 in mice or mutation in humans causes hypogonadotropic hypogonadism (137, 196, 220, 575)....
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TL;DR: Kiss1 gene encodes a family of neuropeptides called kisspeptins, which activate the receptor G protein-coupled receptor-54 and play a role in the neuroendocrine regulation of GnRH secretion and whether estradiol regulates KiSS-1 in the forebrain of the female mouse is examined.
Abstract: The Kiss1 gene encodes a family of neuropeptides called kisspeptins, which activate the receptor G protein-coupled receptor-54 and play a role in the neuroendocrine regulation of GnRH secretion. We examined whether estradiol (E2) regulates KiSS-1 in the forebrain of the female mouse by comparing KiSS-1 mRNA expression among groups of ovary-intact (diestrus), ovariectomized (OVX), and OVX plus E2-treated mice. In the arcuate nucleus (Arc), KiSS-1 expression increased after ovariectomy and decreased with E2 treatment. Conversely, in the anteroventral periventricular nucleus (AVPV), KiSS-1 expression was reduced after ovariectomy and increased with E2 treatment. To determine whether the effects of E2 on KiSS-1 are mediated through estrogen receptor (ER)alpha or ERbeta, we evaluated the effects of E2 in OVX mice that lacked functional ERalpha or ERbeta. In OVX mice that lacked functional ERalpha, KiSS-1 mRNA did not respond to E2 in either the Arc or AVPV, suggesting that ERalpha is essential for mediating the inhibitory and stimulatory effects of E2. In contrast, KiSS-1 mRNA in OVX mice that lacked functional ERbeta responded to E2 exactly as wild-type animals. Double-label in situ hybridization revealed that virtually all KiSS-1-expressing neurons in the Arc and AVPV coexpress ERalpha, suggesting that the effects of E2 are mediated directly through KiSS-1 neurons. We conclude that KiSS-1 neurons in the Arc, which are inhibited by E2, may play a role in the negative feedback regulation of GnRH secretion, whereas KiSS-1 neurons in the AVPV, which are stimulated by E2, may participate in the positive feedback regulation of GnRH secretion.
984 citations
TL;DR: It is demonstrated that kisspeptin exerts a potent depolarizing effect on the excitability of almost all adult GnRH neurons and that the responsiveness of Gn RH neurons tokisspeptin increases over postnatal development.
Abstract: We examined the role of kisspeptin and its receptor, the G-protein-coupled receptor GPR54, in governing the onset of puberty in the mouse. In the adult male and female mouse, kisspeptin (10-100 nM) evoked a remarkably potent, long-lasting depolarization of >90% of gonadotropin-releasing hormone (GnRH)-green fluorescent protein neurons in situ. In contrast, in juvenile [postnatal day 8 (P8) to P19] and prepubertal (P26-P33) male mice, kisspeptin activated only 27 and 44% of GnRH neurons, respectively. This developmental recruitment of GnRH neurons into a kisspeptin-responsive pool was paralleled by an increase in the ability of centrally administered kisspeptin to evoke luteinizing hormone secretion in vivo. To learn more about the mechanisms through which kisspeptin-GPR54 signaling at the GnRH neuron may change over postnatal development, we performed quantitative in situ hybridization for kisspeptin and GPR54 transcripts. Approximately 90% of GnRH neurons were found to express GPR54 mRNA in both juvenile and adult mice, without a detectable difference in the mRNA content between the age groups. In contrast, the expression of KiSS-1 mRNA increased dramatically across the transition from juvenile to adult life in the anteroventral periventricular nucleus (AVPV; p < 0.001). These results demonstrate that kisspeptin exerts a potent depolarizing effect on the excitability of almost all adult GnRH neurons and that the responsiveness of GnRH neurons to kisspeptin increases over postnatal development. Together, these observations suggest that activation of GnRH neurons by kisspeptin at puberty reflects a dual process involving an increase in kisspeptin input from the AVPV and a post-transcriptional change in GPR54 signaling within the GnRH neuron.
940 citations
Cites background or methods from "A Role for Kisspeptins in the Regul..."
...…central administration of kisspeptin into the brain produces an extraordinarily potent inductive effect on GnRH release and, consequently, luteinizing hormone (LH) and follicle-stimulating hormone secretion (Gottsch et al., 2004; Irwig et al., 2004; Messager et al., 2005; Navarro et al., 2005a,b)....
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...Kisspeptin-10, which comprises the 10 amino acids at the C terminus of the full-length kisspeptin peptide, has the same potency as kisspeptin-52, the secreted peptide, in stimulating the GPR54 receptor in vitro (Muir et al., 2001) and in evoking LH secretion in vivo (Gottsch et al., 2004)....
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...Single-label (KiSS-1 mRNA) and double-label (GPR54 mRNA/GnRH mRNA) in situ hybridization was performed as described previously (Gottsch et al., 2004; Irwig et al., 2004)....
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...This corroborates the extraordinarily potent effects of nanomolar to femtomolar doses of kisspeptin on gonadotropin secretion in vivo (Gottsch et al., 2004; Thompson et al., 2004; Navarro et al., 2005a)....
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...Freehand intracerebroventricular injections in the lateral cerebral ventricle were performed as described previously (Gottsch et al., 2004)....
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TL;DR: These results demonstrate that GnRH neurons are direct targets for regulation by kisspeptins and that KiSS-1 mRNA is regulated by gonadal hormones, suggesting that Ki SS-1 neurons play an important role in the feedback regulation of gonadotropin secretion.
Abstract: The KiSS-1 gene codes for a family of neuropeptides called kisspeptins which bind to the G-protein-coupled receptor GPR54. To assess the possible effects of kisspeptins on gonadotropin secretion, we injected kisspeptin-52 into the lateral cerebral ventricles of adult male rats and found that kisspeptin-52 increased the serum levels of luteinizing hormone (p < 0.05). To determine whether the kisspeptin-52-induced stimulation of luteinizing hormone secretion was mediated by gonadotropin-releasing hormone (GnRH), we pretreated adult male rats with a GnRH antagonist (acyline), then challenged the animals with intracerebroventricularly administered kisspeptin-52. The GnRH antagonist blocked the kisspeptin-52-induced increase in luteinizing hormone. To examine whether kisspeptins stimulate transcriptional activity in GnRH neurons, we administered kisspeptin-52 intracerebroventricularly and found by immunocytochemistry that 86% of the GnRH neurons coexpressed Fos 2 h after the kisspeptin-52 challenge, whereas fewer than 1% of the GnRH neurons expressed Fos following injection of the vehicle alone (p < 0.001). To assess whether kisspeptins can directly act on GnRH neurons, we used double-label in situ hybridization and found that 77% of the GnRH neurons coexpress GPR54 mRNA. Finally, to determine whether KiSS-1 gene expression is regulated by gonadal hormones, we measured KiSS-1 mRNA levels by single-label in situ hybridization in intact and castrated males and found significantly higher levels in the arcuate nucleus of castrates. These results demonstrate that GnRH neurons are direct targets for regulation by kisspeptins and that KiSS-1 mRNA is regulated by gonadal hormones, suggesting that KiSS-1 neurons play an important role in the feedback regulation of gonadotropin secretion.
873 citations
Cites methods from "A Role for Kisspeptins in the Regul..."
...Signal-to-background ratios (SBRs) for individual cells were calculated; an individual cell was considered to be double-labeled if it had an SBR of 3 or more. For each animal, the amount of double-labeling was calculated as a percentage of the total number of GnRH-mRNA-expressing cells and then averaged across animals to produce mean ± SEM. Experiment 4: Steroid Regulation of KiSS-1 mRNA Expression Animal and Tissue Preparation. Rats (n = 3 per group) were either left intact or castrated under ketamine (100 mg/ml)/xylazine (20 mg/ml) anesthesia (5.0:1.6 ratio). Seven days later, the animals were euthanized with CO 2 , quickly decapitated, and brains were removed and frozen on dry ice. Sections in the coronal plane (20 μm) from the rostral-caudal extent of the arcuate nucleus were cut on a cryostat, thaw-mounted onto SuperFrost Plus slides, and stored at –80°C. Radiolabeled KiSS-1 cRNA Riboprobe. Antisense and sense mouse KiSS-1 probes were generated as previously described [...
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References
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Book•
15 Jan 1994
TL;DR: The gametes, fertilization and early embryogenesis the reproductive systems - the female, the male the pituitary and the hypothalmus, and the reproductive processes and their control.
Abstract: Volume 1: The gametes, fertilization and early embryogenesis the reproductive systems - the female, the male the pituitary and the hypothalmus. Volume 2: Reproductive behaviour and its control reproductive processes and their control.
7,667 citations
TL;DR: Puberty is initiated when gonadotropin-releasing hormone begins to be secreted by the hypothalamus, and complementary genetic approaches in humans and mice identified genetic factors that determine the onset of puberty.
Abstract: Background Puberty, a complex biologic process involving sexual development, accelerated linear growth, and adrenal maturation, is initiated when gonadotropin-releasing hormone begins to be secreted by the hypothalamus. We conducted studies in humans and mice to identify the genetic factors that determine the onset of puberty. Methods We used complementary genetic approaches in humans and in mice. A consanguineous family with members who lacked pubertal development (idiopathic hypogonadotropic hypogonadism) was examined for mutations in a candidate gene, GPR54, which encodes a G protein–coupled receptor. Functional differences between wild-type and mutant GPR54 were examined in vitro. In parallel, a Gpr54-deficient mouse model was created and phenotyped. Responsiveness to exogenous gonadotropin-releasing hormone was assessed in both the humans and the mice. Results Affected patients in the index pedigree were homozygous for an L148S mutation in GPR54, and an unrelated proband with idiopathic hypogonadotro...
2,253 citations
"A Role for Kisspeptins in the Regul..." refers background in this paper
...Together, these observations argue that the hypogonadism in humans and mice with dysfunctional or deletional mutations in GPR54 is attributable to a central defect (7)....
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TL;DR: Comparing the distribution of the classical and novel forms of ER mRNA‐expressing neurons in the central nervous system (CNS) of the rat with in situ hybridization histochemistry provides evidence that the region‐specific expression of ER‐α, ER‐β, or both may be important in determining the physiological responses of neuronal populations to estrogen action.
Abstract: Estrogen plays a profound role in regulating the structure and function of many neuronal systems in the adult rat brain. The actions of estrogen were thought to be mediated by a single nuclear estrogen receptor (ER) until the recent cloning of a novel ER (ER-beta). To ascertain which ER is involved in the regulation of different brain regions, the present study compared the distribution of the classical (ER-alpha) and novel (ER-beta) forms of ER mRNA-expressing neurons in the central nervous system (CNS) of the rat with in situ hybridization histochemistry. Female rat brain, spinal cord, and eyes were frozen, and cryostat sections were collected on slides, hybridized with [35S]-labeled antisense riboprobes complimentary to ER-alpha or ER-beta mRNA, stringently washed, and opposed to emulsion. The results of these studies revealed the presence of ER-alpha and ER-beta mRNA throughout the rostral-caudal extent of the brain and spinal cord. Neurons of the olfactory bulb, supraoptic, paraventricular, suprachiasmatic, and tuberal hypothalamic nuclei, zona incerta, ventral tegmental area, cerebellum (Purkinje cells), laminae III-V, VIII, and IX of the spinal cord, and pineal gland contained exclusively ER-beta mRNA. In contrast, only ER-alpha hybridization signal was seen in the ventromedial hypothalamic nucleus and subfornical organ. Perikarya in other brain regions, including the bed nucleus of the stria terminalis, medial and cortical amygdaloid nuclei, preoptic area, lateral habenula, periaqueductal gray, parabrachial nucleus, locus ceruleus, nucleus of the solitary tract, spinal trigeminal nucleus and superficial laminae of the spinal cord, contained both forms of ER mRNA. Although the cerebral cortex and hippocampus contained both ER mRNAs, the hybridization signal for ER-alpha mRNA was very weak compared with ER-beta mRNA. The results of these in situ hybridization studies provide detailed information about the distribution of ER-alpha and ER-beta mRNAs in the rat CNS. In addition, this comparative study provides evidence that the region-specific expression of ER-alpha, ER-beta, or both may be important in determining the physiological responses of neuronal populations to estrogen action.
2,247 citations
TL;DR: The present study shows that loss of function of GPR54 is a cause of IHH, and it identifies GPR 54 and possibly KiSS1 protein-derived peptide as playing a major and previously unsuspected role in the physiology of the gonadotropic axis.
Abstract: Hypogonadotropic hypogonadism is defined as a deficiency of the pituitary secretion of follicle-stimulating hormone and luteinizing hormone, which results in the impairment of pubertal maturation and of reproductive function. In the absence of pituitary or hypothalamic anatomical lesions and of anosmia (Kallmann syndrome), hypogonadotropic hypogonadism is referred to as isolated hypogonadotropic hypogonadism (IHH). A limited number of IHH cases are due to loss-of-function mutations of the gonadotropin-releasing hormone receptor. To identify additional gene defects leading to IHH, a large consanguineous family with five affected siblings and with a normal gonadotropin-releasing hormone receptor coding sequence was studied. Homozygosity whole-genome mapping allowed the localization of a new locus within the short arm of chromosome 19 (19p13). Sequencing of several genes localized within this region showed that all affected siblings of the family carried a homozygous deletion of 155 nucleotides in the GPR54 gene. This deletion encompassed the splicing acceptor site of intron 4-exon 5 junction and part of exon 5. The deletion was absent or present on only one allele in unaffected family members. GPR54 has been initially identified as an orphan G protein-coupled receptor with 40% homology to galanin receptors. Recently, a 54-aa peptide derived from the KiSS1 protein was identified as a ligand of GPR54. The present study shows that loss of function of GPR54 is a cause of IHH, and it identifies GPR54 and possibly KiSS1 protein-derived peptide as playing a major and previously unsuspected role in the physiology of the gonadotropic axis.
2,147 citations
TL;DR: AR and ER may modulate nonolfactory sensory information as well since labeled cells were found in regions involved in the central relay of somatosensory information, including the mesencephalic nucleus of the trigeminal nerve, the ventral thalamic nuclear group, and the dorsal horn of the spinal cord.
Abstract: The distribution of cells that express mRNA encoding the androgen (AR) and estrogen (ER) receptors was examined in adult male and female rats by using in situ hybridization. Specific labeling appeared to be largely, if not entirely, localized to neurons. AR and ER mRNA-containing neurons were widely distributed in the rat brain, with the greatest densities of cells in the hypothalamus, and in regions of the telencephalon that provide strong inputs in the medial preoptic and ventromedial nuclei, each of which is thought to play a key role in mediating the hormonal control of copulatory behavior, as well as in the lateral septal nucleus, the medial and cortical nuclei of the amygdala, the amygdalohippocampal area, and the bed nucleus of the stria terminalis. Heavily labeled ER mRNA-containing cells were found in regions known to be involved in the neural control of gonadotropin release, such as the anteroventral periventricular and the arcuate nuclei, but only a moderate density of labeling for AR mRNA was found over these nuclei. In addition, clearly labeled cells were found in regions with widespread connections throughout the brain, including the lateral hypothalamus, intralaminar thalamic nuclei, and deep layers of the cerebral cortex, suggesting that AR and ER may modulate a wide variety of neural functions. Each part of Ammon's horn contained AR mRNA-containing cells, as did both parts of the subiculum, but ER mRNA appeared to be less abundant in the hippocampal formation. Moreover, AR and ER mRNA-containing cells were also found in olfactory regions of the cortex and in both the main and accessory olfactory bulbs. AR and ER may modulate nonolfactory sensory information as well since labeled cells were found in regions involved in the central relay of somatosensory information, including the mesencephalic nucleus of the trigeminal nerve, the ventral thalamic nuclear group, and the dorsal horn of the spinal cord. Furthermore, heavily labeled AR mRNA-containing cells were found in the vestibular nuclei, the cochlear nuclei, the medial geniculate nucleus, and the nucleus of the lateral lemniscus, which suggests that androgens may alter the central relay of vestibular and auditory information as well. However, of all the regions involved in sensory processing, the heaviest labeling for AR and ER mRNA was found in areas that relay visceral sensory information such as the nucleus of the solitary tract, the area postrema, and the subfornical organ. We did not detect ER mRNA in brainstem somatic motoneurons, but clearly labeled AR mRNA-containing cells were found in motor nuclei associated with the fifth, seventh, tenth, and twelfth cranial nerves. Similarly, spinal motoneurons contained AR but not ER mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)
2,058 citations