kiss1-protein--human and Body-Weight

Kisspeptin (encoded by the Kiss1 gene) and its receptor, KISS1R (encoded by the Kiss1r gene), have well-established roles in stimulating reproduction via central actions on reproductive neural circuits, but recent evidence suggests that kisspeptin signaling also influences metabolism and energy balance. Indeed, both Kiss1 and Kiss1r are expressed in many metabolically-relevant peripheral tissues, including both white and brown adipose tissue, the liver, and the pancreas, suggesting possible actions on these tissues or involvement in their physiology. In addition, there may be central actions of kisspeptin signaling, or factors co-released from kisspeptin neurons, that modulate metabolic, feeding, or thermoregulatory processes. Accumulating data from animal models suggests that kisspeptin signaling regulates a wide variety of metabolic parameters, including body weight and energy expenditure, adiposity and adipose tissue function, food intake, glucose metabolism, respiratory rates, locomotor activity, and thermoregulation. Herein, the current evidence for the involvement of kisspeptin signaling in each of these physiological parameters is reviewed, gaps in knowledge identified, and future avenues of important research highlighted. Collectively, the discussed findings highlight emerging non-reproductive actions of kisspeptin signaling in metabolism and energy balance, in addition to previously documented roles in reproductive control, but also emphasize the need for more research to resolve current controversies and uncover underlying molecular and physiological mechanisms.

Topics: Animals; Body Weight; Energy Metabolism; Humans; Kisspeptins; Mice; Mice, Knockout; Receptors, Kisspeptin-1

Calorie restriction and overtraining are increasingly seen in young men who suffer from increasing societal pressure to attain a perceived ideal male body image. The resulting energy deficit can lead to multiple endocrine consequences, including suppression of the male gonadal axis.. We reviewed the literature, including two unpublished cases.. Hypogonadotropic hypogonadism can occur in the context of energy deprivation in young otherwise healthy men and may be underrecognized. The evidence suggests that gonadal axis suppression and associated hormonal abnormalities represent an adaptive response to increased physiological stress and total body energy deficit. The pathophysiology likely involves hypothalamic suppression due to dysregulation of leptin, ghrelin and pro-inflammatory cytokines. The gonadal axis suppression is functional, because it can be reversible with weight gain. Treatment should focus on reversing the existing energy deficit to achieve a healthy body weight, including psychiatric input where required.

Topics: Adolescent; Adult; Anorexia; Body Weight; Exercise; Ghrelin; Humans; Hypogonadism; Insulin-Like Growth Factor I; Kisspeptins; Male; Testosterone; Weight Loss; Young Adult

Although the close link between body weight and fertility has been known for eons, only recently have the peripheral signals and neuroendocrine networks responsible for such a phenomenon begun to be identified. A key event in this field was the cloning of the adipocyte-derived hormone leptin, which has been demonstrated as a pivotal regulator for the integration of energy homeostasis and reproduction. In addition, other metabolic hormones, such as insulin, contribute to this physiological integration. Moreover, compelling experimental evidence implicates hormonal products of the gastrointestinal tract as adjuncts in the complex coordination and regulation of body weight and reproduction. Here, we review recent studies evaluating the reproductive effects and sites of action of ghrelin and PYY3-36, two hormonal signals of gastrointestinal origin involved in the control food intake and energy balance. In addition, we summarize the potential contribution of kisspeptin, the recently characterized gatekeeper of the GnRH system encoded by Kiss1 gene, to integrating reproductive function and energy status. Evidence suggests that besides having direct gonadal effects, ghrelin may participate in the regulation of gonadotropin secretion and it may influence the timing of puberty. Likewise, PYY3-36 modulates GnRH and gonadotropin release. In addition, the hypothalamic KiSS-1 system is sensitive to nutritional status, and its diminished expression during states of negative energy balance might contribute to the suppression of reproductive function in such conditions. We propose that the peripheral hormones, ghrelin and PYY3-36, and the central neuropeptide, kisspeptin, are 'novel' players in the neuroendocrine networks that integrate energy balance and reproduction.

Topics: Animals; Appetite Regulation; Body Weight; Energy Metabolism; Gastric Mucosa; Ghrelin; Gonadotropin-Releasing Hormone; Gonadotropins; Humans; Kisspeptins; Models, Biological; Peptide Fragments; Peptide Hormones; Peptide YY; Puberty; Reproduction; Signal Transduction; Tumor Suppressor Proteins

Kisspeptin is a critical regulator of normal reproductive function. A single injection of kisspeptin in healthy human volunteers potently stimulates gonadotropin release. However, the effects of kisspeptin on gonadotropin release in women with hypothalamic amenorrhea (HA) and the effects of repeated administration of kisspeptin to humans are unknown.. The aim of this study was to determine the effects of acute and chronic kisspeptin administration on gonadotropin release in women with HA.. We performed a prospective, randomized, double-blinded, parallel design study. Women with HA received twice-daily sc injections of kisspeptin (6.4 nmol/kg) or 0.9% saline (n = 5 per group) for 2 wk. Changes in serum gonadotropin and estradiol levels, LH pulsatility, and ultrasound measurements of reproductive activity were assessed.. On the first injection day, potent increases in serum LH and FSH were observed after sc kisspeptin injection in women with HA (mean maximal increment from baseline within 4 h after injection: LH, 24.0 +/- 3.5 IU/liter; FSH, 9.1 +/- 2.5 IU/liter). These responses were significantly reduced on the 14th injection day (mean maximal increment from baseline within 4 h postinjection: LH, 2.5 +/- 2.2 IU/liter, P < 0.05; FSH, 0.5 +/- 0.5 IU/liter, P < 0.05). Subjects remained responsive to GnRH after kisspeptin treatment. No significant changes in LH pulsatility or ultrasound measurements of reproductive activity were observed.. Acute administration of kisspeptin to women with infertility due to HA potently stimulates gonadotropin release, but chronic administration of kisspeptin results in desensitization to its effects on gonadotropin release. These data have important implications for the development of kisspeptin as a novel therapy for reproductive disorders in humans.

Topics: Adult; Amenorrhea; Body Mass Index; Body Weight; Female; Follicle Stimulating Hormone; Gonadotropins; Humans; Hypothalamus; Kisspeptins; Luteinizing Hormone; Spectrometry, Mass, Electrospray Ionization; Tachyphylaxis; Tumor Suppressor Proteins; Weight Gain; Young Adult

Central precocious puberty (CPP) is a widespread developmental abnormality. The application of gonadotrophin-releasing hormone agonist (GnRHa) is widely useful for the medical therapy of CPP. This study aimed to investigate the combination effect and mechanism of indirubin-3'-oxime (I3O), an active ingredient analogue of traditional Chinese medicine, and GnRHa treatment on the progression of CPP. First, female C57BL/6 mice were fed with a high-fat diet (HFD) for the induction of precocious puberty and treated with GnRHa and I3O alone or in combination. Development of sexual maturation, bone growth and obesity were determined by vaginal opening detection, H&E staining and ELISA. The protein and mRNA expression levels of related genes were evaluated via western blotting, immunohistochemical method and RT-qPCR. Subsequently, tBHQ, an inhibitor of ERK, was applied to verify whether the mechanism of I3O was associated with this signaling. The results showed that the treatment of I3O alone or in combination with GnRHa could alleviate the HFD-induced earlier vaginal opening and serum levels of the gonadal hormone in mice. And, I3O could significantly eliminate the role of growth deceleration of GnRHa in bone development and reversed the side effect of GnRHa on body weight. More importantly, we found that I3O decreased the expression of KISS-1 and GPR54 by suppressing the phosphorylation of ERK1/2 and Sp1 in the hypothalamus in mice. In summary, these data indicated that I3O could promote the efficacy of GnRHa in HFD-induced precocious puberty, and maintain bone growth and body weight in mice via the ERK-Sp1-KISS-1/GPR54 axis.

Topics: Animals; Body Weight; Bone Development; Female; Kisspeptins; Mice; Mice, Inbred C57BL; Obesity; Oximes

This study was conducted to determine the possible effects of long-term exogenous kisspeptin and its antagonist P234 on serum, liver and adipose tissue fatty acids (FA) profiles, as well as body weight, in female rats. Kisspeptin (50 pmol) and P234 (1 nmol) were administrated to the weaned Sprague-Dawley female rats by an intracerebroventricular injection from the 26th postnatal day to the 60th postnatal day. Percentages of the serum total saturated FA (∑SFA) and total monounsaturated FA (∑MUFA) were lower in the kisspeptin group. In the adipose tissue, ∑SFA was lower and total unsaturated FA higher in the P234 group. Moreover, long-term central kisspeptin injection caused a decrease in the body weight. When compared to the kisspeptin group, the final body weights were higher in the P234 and kisspeptin + P234 groups. According to our results, we suggest that kisspeptin has a regulatory role in FA metabolism and regulation of body weight.

Topics: Adipose Tissue; Animals; Body Weight; Fatty Acids; Female; Kisspeptins; Liver; Rats; Rats, Sprague-Dawley

Undernutrition limits reproduction through inhibition of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) secretion. Because KNDy neurons coexpress neuropeptides that play stimulatory (kisspeptin and neurokinin B [NKB]) and inhibitory (dynorphin) roles in pulsatile GnRH/LH release, we hypothesized that undernutrition would inhibit kisspeptin and NKB expression at the same time as increasing dynorphin expression. Fifteen ovariectomized lambs were either fed to maintain pre-study body weight (controls) or feed-restricted to lose 20% of pre-study body weight (FR) over 13 weeks. Blood samples were collected and plasma from weeks 0 and 13 were assessed for LH by radioimmunoassay. At week 13, animals were killed, and brain tissue was processed for assessment of KNDy peptide mRNA or protein expression. Mean LH and LH pulse amplitude were lower in FR lambs compared to controls. We observed lower mRNA abundance for kisspeptin within KNDy neurons of FR lambs compared to controls with no significant change in mRNA for NKB or dynorphin. We also observed that FR lambs had fewer numbers of arcuate nucleus kisspeptin and NKB perikarya compared to controls. These findings support the idea that KNDy neurons are important for regulating reproduction during undernutrition in female sheep.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dynorphins; Female; Gonadotropin-Releasing Hormone; Kisspeptins; Malnutrition; Neurokinin B; Neurons; RNA, Messenger; Sheep

Many cytokines have been proposed to regulate reproduction due to their actions on hypothalamic kisspeptin cells, the main modulators of gonadotropin-releasing hormone (GnRH) neurons. Hormones such as leptin, prolactin and growth hormone are good examples of cytokines that lead to Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway activation, consequently exerting effects in kisspeptin neurons. Different studies have investigated how specific components of the JAK/STAT signaling pathway affect the functions of kisspeptin cells, but the role of the suppressor of cytokine signaling 3 (SOCS3) in mediating cytokine actions in kisspeptin cells remains unknown. Cre-Loxp technology was used in the present study to ablate Socs3 expression in kisspeptin cells (Kiss1/Socs3-KO). Then, male and female control and Kiss1/Socs3-KO mice were evaluated for sexual maturation, energy homeostasis features, and fertility. It was found that hypothalamic Kiss1 mRNA expression is significantly downregulated in Kiss1/Socs3-KO mice. Despite reduced hypothalamic Kiss1 mRNA content, these mice did not present any sexual maturation or fertility impairments. Additionally, body weight gain, leptin sensitivity and glucose homeostasis were similar to control mice. Interestingly, Kiss1/Socs3-KO mice were partially protected against lipopolysaccharide (LPS)-induced body weight loss. Our results suggest that Socs3 ablation in kisspeptin cells partially prevents the sickness behavior induced by LPS, suggesting that kisspeptin cells can modulate energy metabolism in mice in certain situations.

Topics: Animals; Body Weight; Cytokines; Female; Kisspeptins; Leptin; Lipopolysaccharides; Male; Mice; RNA, Messenger; Suppressor of Cytokine Signaling 3 Protein; Weight Loss

Kisspeptin, a neuropeptide hormone, has been firmly established as a key regulator of the hypothalamic-pituitary-gonadal axis and mammalian reproductive behaviour. In recent years, a growing body of evidence has emerged suggesting a role for kisspeptin in regulating metabolic processes. This data suggest that kisspeptin exerts its metabolic effects indirectly via gonadal hormones and/or directly via the kisspeptin receptor in the brain, pancreas and brown adipose tissue. Kisspeptin receptor knockout studies indicate that kisspeptin may play sexually dimorphic roles in the physiological regulation of energy expenditure, food intake and body weight. Some, but not all, in vitro work demonstrates positive effects on glucose-stimulated insulin secretion, which is more marked at higher kisspeptin concentrations. Acute and chronic in vivo rodent, non-human primate and human studies reveal enhancement of glucose-stimulated insulin secretion in response to pharmacological doses of kisspeptin. Although significant progress has been made in elucidating the metabolic effects of kisspeptin, further mechanistic work and translational studies are required to address unanswered questions and establish the metabolic effects of kisspeptin in diverse human populations (including women, people with obesity and people with diabetes).

Topics: Animals; Body Weight; Energy Metabolism; Female; Glucose; Humans; Kisspeptins; Mammals; Mice; Mice, Knockout; Receptors, Kisspeptin-1

Central kisspeptin action is well known in reproductive regulation; however, its peripheral action is not well understood. This study aimed to 1) compare serum or cerebrospinal fluid (CSF) kisspeptin levels between different body mass index (BMI) groups 2) compare the levels of kisspeptin between serum and CSF, and 3) determine correlations between serum or CSF kisspeptin levels with clinical, metabolic, and reproductive parameters. There were 40 male subjects undergoing operations with lumbar puncture anesthesia. Subgroup analysis was performed to compare between the normal (n = 12), overweight (n = 10), and obese groups (n = 17). One lean subject was recruited for correlation analysis. Serum kisspeptin levels were significantly higher in the obese group when compared to the normal weight and overweight groups even after adjusting for age or diastolic blood pressure (DBP) (p < 0.05 all). Serum leptin levels were significantly higher in the obese group when compared to the normal weight and overweight groups (p < 0.05 all). CSF kisspeptin levels were below the minimum detectable concentration for the assay (<0.06 ng/mL). Serum kisspeptin was positively correlated with body weight, BMI, plasma insulin, the homeostatic model assessment for insulin resistance (HOMA-IR), and serum leptin but was negatively correlated with plasma LH (p < 0.05 all). In conclusion, serum kisspeptin was related to obesity, leptin, insulin, and insulin resistance, while CSF kisspeptin was below the limits of detection. Thus, peripheral kisspeptin might have a role in metabolic regulation.

Topics: Adult; Anesthesia; Body Mass Index; Body Weight; Female; Humans; Insulin Resistance; Kisspeptins; Leptin; Male; Obesity; Overweight; Reproduction; Spinal Puncture

Eucommia ulmoides Oliv. leaves are the dry leaves of Eucommia ulmoides Oliv. Modern studies have shown that Eucommia ulmoides Oliv. leaves and its extracts have many pharmacological effects, such as regulating hypothalamus pituitary ovary (HPO) axis function, estrogen like effects, correcting insulin resistance (IR), regulating lipids, and reducing weight, which are consistent with the clinical manifestations in polycystic ovary syndrome (PCOS) patients. PCOS patients often have HPO axis disorder, low estrogen, high androgen, high IR complication rate, and obesity. Previous preclinical studies have shown that total flavonoids from Eucommia ulmoides Oliv. leaves (TFEL) can improve the imbalance in sex hormone secretion in perimenopausal animal models by regulating the function of the HPO axis. Thus, it is important to understand if flavonoids are the active parts of Eucommia ulmoides Oliv. leaves that interfere with polycystic ovary syndrome with insulin resistance (PCOS-IR), and determine the regulatory role they play in sex hormones and IR?. Investigate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway in the ovary and kisspeptin/insulin like growth factor/leptin receptor1/androgen receptor (Kiss1/IGF-1/LEPR/AR) in the HPO axis to determine the mechanism of TFEL intervention in a rat model of PCOS-IR model rats.. A rat model of PCOS-IR was established using a high-fat diet (49 d) combined with letrozole (1 mg/kg·d, for 28 d). Then, metformin (300 mg/kg·d) and TFEL (220 mg/kg·d, 110 mg/kg·d, and 55 mg/kg·d) were administered continuously for 21 days. At the end of the experiment, samples were taken and the related indexes were measured.. TFEL reduced the body weight, Lee's index, ovarian index, ovarian area and ovarian volume, increased serum E. TFEL can inhibit ovarian hyperplasia, regulate disorders of glucose and lipid metabolism and improve the secretion of sex hormones, by regulating the expression of PI3K/AKT signaling pathway-related proteins in the ovary and Kiss1/IGF-1/LEPR/AR in the HPO axis.

Topics: Animals; Body Weight; Diet, High-Fat; Disease Models, Animal; Eucommiaceae; Female; Flavonoids; Gonadal Steroid Hormones; Hypothalamus; Insulin Resistance; Insulin-Like Growth Factor I; Kisspeptins; Letrozole; Metformin; Ovary; Pancreas; Phosphatidylinositol 3-Kinases; Pituitary Gland; Plant Extracts; Plant Leaves; Polycystic Ovary Syndrome; Proto-Oncogene Proteins c-akt; Rats, Sprague-Dawley; Receptors, Androgen; Receptors, Leptin

While undernutrition is known to impair reproduction at the level of the brain, the components responsible for this in the brain remain to be fully understood. Using male sheep we examined the effect of undernutrition on two stimulatory molecules in the brain critical for reproduction: kisspeptin and neurokinin B. Feed restriction for several weeks resulted in decreased luteinizing hormone in the blood indicating reproductive function was suppressed. In addition, undernutrition also reduced both kisspeptin and neurokinin B levels within a region of the brain involved in reproduction, the hypothalamus. Given that they have stimulatory roles in reproduction, we believe that undernutrition acts in the brain to reduce kisspeptin and neurokinin B levels leading to the reduction in luteinizing hormone secretion. In summary, long-term undernutrition inhibits reproductive function in sheep through suppression of kisspeptin and neurokinin B within the brain.

Topics: Animals; Body Weight; Gonadotropin-Releasing Hormone; Kisspeptins; Luteinizing Hormone; Male; Malnutrition; Neurokinin B; Receptors, Neurokinin-3; RNA, Messenger; Sheep

Bisphenol A (BPA) is a compound used in the polymerization of plastic polycarbonates. It is an endocrine disruptor and it has been postulated to be an obesogen. Our objective was to determine the influence of perinatal exposure to BPA on body weight, hormone levels, metabolic parameters and hypothalamic signals that regulate food intake and kisspeptin system in adult male rats. Male rats were exposed to 50 μg/kg/day of BPA or vehicle from day 9 of gestation to weaning in the drinking water. Since weaning, they were fed with control or high fat diet for 20 weeks. Perinatal exposure to BPA impaired glucose homeostasis, induced obesity and increased food intake in adult male rats altering hypothalamic signals, partially mimicking and/or producing an exacerbation of the effects of feeding fat diet. We also observed an increase in kisspeptin expression by BPA exposure. Evidences shown in this work support the metabolic disruptor hypothesis for BPA.

Topics: Animals; Benzhydryl Compounds; Body Weight; Diet, High-Fat; Disease Models, Animal; Endocrine Disruptors; Female; Glucose; Kisspeptins; Male; Obesity; Phenols; Pregnancy; Prenatal Exposure Delayed Effects; Rats

Although anorexia nervosa is classified as a psychiatric disorder associated with socio-environmental and psychological factors, a deeper insight into the dominant neurobiological basis is needed to develop a more effective approach of treatment. Given the high contribution of genetic predisposition and the underlying pathophysiology of neurohormonal circuits, it seems that pharmacological targeting of these mechanisms may provide us with better therapeutic outcomes.. Kisspeptin reinforced food consumption in an activity-based rodent model of anorexia changing a pattern of weight loss.. We suspect that kisspeptin through modulation of hypothalamic GABAergic signaling increases food intake, and thus positively alters brain metabolism.

Topics: Animals; Anorexia; Body Weight; Brain Stem; Feeding Behavior; Female; Hypothalamus; Kisspeptins; Metabolome; Proton Magnetic Resonance Spectroscopy; Rats, Wistar

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are widespread and persistent chemicals in the environment, and limited data about their effects on puberty development are available. In order to explore the effects of neonatal and juvenile PFOA/PFOS exposure on puberty maturation, female rats were injected with PFOA or PFOS at 0.1, 1 and 10 mg/kg/day during postnatal day (PND) 1-5 or 26-30. The day of vaginal opening (VO) and first estrus were significantly advanced in 10 mg/kg PFOA, 1 and 10 mg/kg PFOS groups after neonatal and juvenile exposure. Besides, neonatal PFOA/PFOS exposure increased body weight and anogenital distance (AGD) in a non-dose-dependent manner. Estradiol and luteinizing hormone levels were also increased with more frequent occurrences of irregular estrous cycles in 0.1 and 1 mg/kg PFOA/PFOS exposure groups. Although no altered ovarian morphology was observed, follicles numbers were reduced in neonatal groups. Kiss1, Kiss1r and ERα mRNA expressions were downregulated after two periods' exposure in the hypothalamic anteroventral periventricular (AVPV) and arcuate (ARC) nuclei. PFOA/PFOS exposure also suppressed kisspeptin fiber intensities, especially at the high dose. In conclusion, neonatal and juvenile are critical exposure periods, during which puberty maturation may be vulnerable to environmental exposure of PFOA/PFOS, and kisspeptin system plays a key role during these processes.

Topics: Alkanesulfonic Acids; Animals; Body Weight; Caprylates; Down-Regulation; Estradiol; Estrogen Receptor alpha; Estrous Cycle; Female; Fluorocarbons; Hypothalamus; Kisspeptins; Luteinizing Hormone; Ovarian Follicle; Rats; Receptors, Kisspeptin-1; RNA, Messenger; Sexual Maturation

Many animals exhibit remarkable metabolic and reproductive adaptations to seasonal changes in their environment. When day length shortens, Djungarian hamsters (Phodopus sungorus) reduce their body weight and inhibit their reproductive activity, whereas the opposite occurs in springtime. These physiological adaptations are considered to depend on photoperiodic changes in hypothalamic genes encoding the peptides kisspeptin (Kp) and RFamide-related peptide 3 (RFRP3) for the control of reproduction, as well as pro-opiomelanocortin and somatostatin for metabolic regulation. The present study investigates the effect of Kp and RFRP3 on long-term body weight regulation, aiming to establish whether metabolic and reproductive hypothalamic networks may interact during adaptation to seasonal physiology. We found that chronic central administration of both Kp and RFRP3 in short photoperiod-adapted male Djungarian hamsters increased body weight, although via different pathways. The effect of Kp was dependent on testicular activity because castration prevented the body weight increase and was associated with an increase in pro-opiomelanocortin and neuropeptide Y expression. On the other hand, the orexigenic effect of RFRP3 was associated with an increase in circulating insulin and leptin levels, although it had no effect on any of the hypothalamic metabolic genes investigated, and did not change circulating levels of sex steroids. Notably, neither Kp, nor RFRP3 altered female hamster metabolic parameters. Thus, using a rodent model exhibiting seasonal changes in reproduction and metabolism, the present study demonstrates that, in addition to its role in the central control of reproduction, Kp also participates in body weight control in a sex-dependent manner via an anabolic action of testosterone. Conversely, RFRP3 affects body weight control in males mostly by acting on adiposity, with no overt effect on the reproductive system in both sexes.

Topics: Animals; Body Weight; Eating; Female; Gene Expression; Insulin; Kisspeptins; Leptin; Male; Neuropeptide Y; Neuropeptides; Neurosecretory Systems; Phodopus; Photoperiod; Pro-Opiomelanocortin; Reproduction; Seasons; Sex Factors; Testis

Kisspeptins, encoded by Kiss1, have emerged as essential regulators of puberty and reproduction by primarily acting on GnRH neurons, via their canonical receptor, Gpr54. Mounting, as yet fragmentary, evidence strongly suggests that kisspeptin signaling may also participate in the control of key aspects of body energy and metabolic homeostasis. However, characterization of such metabolic dimension of kisspeptins remains uncomplete, without an unambiguous discrimination between the primary metabolic actions of kisspeptins vs. those derived from their ability to stimulate the secretion of gonadal hormones, which have distinct metabolic actions on their own. In this work, we aimed to tease apart primary vs. secondary effects of kisspeptins in the control of key aspects of metabolic homeostasis using genetic models of impaired kisspeptin signaling and/or gonadal hormone status.. Body weight (BW) gain and composition, food intake and key metabolic parameters, including glucose tolerance, were comparatively analyzed, in lean and obesogenic conditions, in mice lacking kisspeptin signaling due to global inactivation of Gpr54 (displaying profound hypogonadism; Gpr54. In male mice, global elimination of kisspeptin signaling resulted in decreased BW, feeding suppression and increased adiposity, without overt changes in glucose tolerance, whereas Gpr54. Our data support a global role of kisspeptin signaling in the control of body weight and metabolic homeostasis, with a dominant contribution of gonadal hormone-dependent actions. However, our results document also discernible primary effects of kisspeptin signaling in the regulation of body weight gain, feeding and responses to obesogenic insults, which occur in a sexually-dimorphic manner.. Kisspeptins, master regulators of reproduction, may also participate in the control of key aspects of body energy and metabolic homeostasis; yet, the nature of such metabolic actions remains debatable, due in part to the fact that kisspeptins modulate gonadal hormones, which have metabolic actions on their own. By comparing the metabolic profiles of two mouse models with genetic inactivation of kisspeptin signaling but different gonadal status (hypogonadal vs. preserved gonadal function), we provide herein a systematic dissection of gonadal-dependent vs. -independent metabolic actions of kisspeptins. Our data support a global role of kisspeptin signaling in the control of body weight and metabolic homeostasis, with a dominant contribution of gonadal hormone-dependent actions. However, our results document also discernible primary effects of kisspeptin signaling in the regulation of body weight gain, feeding and responses to obesogenic insults, which occur in a sexually-dimorphic manner. These data pave the way for future analyses addressing the eventual contribution of altered kisspeptin signaling in the development of metabolic alterations, especially in conditions linked to reproductive dysfunction.

Topics: Animals; Body Weight; Diet; Eating; Female; Glucose Intolerance; Gonadal Hormones; Homeostasis; Kisspeptins; Male; Mice; Mice, Knockout; Obesity; Ovariectomy; Receptors, Kisspeptin-1; Signal Transduction; Weight Gain

To clarify the direct effects of androgens, the changes in the hypothalamic levels of reproductive and appetite regulatory factors induced by chronic dihydrotestosterone (DHT) administration were evaluated in female rats. DHT treatment increased the BW and food intake of the ovariectomized rats, but not the estradiol (E2)-treated rats. DHT administration suppressed the expression of a hypothalamic anorexigenic factor. Although the kisspeptin (Kiss1) mRNA levels of the anterior hypothalamic block (the anteroventral periventricular nucleus, AVPV) were increased in the E2-treated rats, DHT administration did not affect the Kiss1 mRNA levels of the AVPV in the ovariectomized or E2-treated rats. Conversely, DHT administration reduced the Kiss1 mRNA levels of the posterior hypothalamic block (the arcuate nucleus, ARC) in the ovariectomized rats. Although the Kiss1 mRNA levels of the posterior hypothalamic block (ARC) were decreased in the E2-treated rats, DHT administration did not affect the Kiss1 mRNA levels of the ARC in these rats. Serum luteinizing hormone levels of these groups exhibited similar patterns to the Kiss1 mRNA levels of the ARC. These results showed that DHT affects the production of hypothalamic reproductive and appetite regulatory factors, and that these effects of DHT differ according to the estrogen milieu.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dihydrotestosterone; Eating; Estradiol; Female; Hypothalamus; Kisspeptins; Ovariectomy; Rats; Rats, Wistar; Reproduction; RNA, Messenger

Obesity may lead to male hypogonadism, the underlying mechanism of which remains unclear. In the present study, we established a murine model of male hypogonadism caused by high-fat diet-induced obesity to verify the following hypotheses: 1) an increased leptin level may be related to decreased secretion of GnRH in obese males, and 2) repression of kisspeptin/GPR54 in the hypothalamus, which is associated with increased leptin levels, may account for the decreased secretion of GnRH and be involved in secondary hypogonadism (SH) in obese males.. Male mice were fed high-fat diet for 19 weeks and divided by body weight gain into diet-induced obesity (DIO) and diet-induced obesity resistant (DIO-R) group. The effect of obesity on the reproductive organs in male mice was observed by measuring sperm count and spermatozoid motility, relative to testis and epididymis weight, testosterone levels, and pathologic changes. Leptin, testosterone, estrogen, and LH in serum were detected by ELISA method. Leptin receptor (Ob-R), Kiss1, GPR54, and GnRH mRNA were measured by real-time PCR in the hypothalamus. Expression of kisspeptin and Ob-R protein was determined by Western blotting. Expression of GnRH and GPR54 protein was determined by immunohistochemical analysis.. We found that diet-induced obesity decreased spermatozoid motility, testis and epididymis relative coefficients, and plasma testosterone and luteinizing hormone levels. An increased number and volume of lipid droplets in Leydig cells were observed in the DIO group compared to the control group. Significantly, higher serum leptin levels were found in the DIO and DIO-R groups. The DIO and DIO-R groups showed significant downregulation of the GnRH, Kiss1, GPR54, and Ob-R genes. We also found decreased levels of GnRH, kisspeptin, GPR54, and Ob-R protein in the DIO and DIO-R groups.. These lines of evidence suggest that downregulation of Ob-R and kisspeptin/GPR54 in the murine hypothalamus may contribute to male hypogonadism caused by high-fat diet-induced obesity.

Topics: Animals; Body Weight; Diet, High-Fat; Disease Models, Animal; Down-Regulation; Gonadotropin-Releasing Hormone; Hypogonadism; Hypothalamus; Kisspeptins; Leptin; Male; Mice; Obesity; Receptors, Kisspeptin-1; Receptors, Leptin; Sperm Motility; Testis

Prenatal undernutrition affects various physiological functions, such as metabolic and reproductive functions, after birth, and such changes are associated with the pathogeneses of certain diseases. It has been hypothesized that these changes are predictive adaptive responses that help individuals to endure similar conditions in the postnatal period. Thus, we evaluated the effects of prenatal undernutrition on the responses of the body weight (BW) regulation system and reproductive functions to fasting in the pre-pubertal period in male rats. Prenatally normally nourished and undernourished rats exhibited similar reductions in BW and visceral fat after 48 h fasting in the pre-pubertal period. Furthermore, these two groups displayed similar fasting-induced patterns of change in their hypothalamic levels of appetite regulatory factors; i.e., neuropeptide Y and pro-opiomelanocortin. These results indicate that prenatal undernutrition had no marked effects on BW regulation in male rats. On the other hand, serum luteinizing hormone and testosterone levels were decreased by 48 h fasting in the prenatally normally nourished rats, whereas the levels of these hormones did not change in the prenatally undernourished rats. However, the hypothalamic mRNA level of kisspeptin 1 (Kiss1), which is a positive regulator of gonadotropin-releasing hormone/gonadotropins, was reduced by fasting in both groups. These results indicate that prenatal undernutrition might attenuate fasting-induced reproductive dysfunction in the postnatal period; however, these changes might not be induced by alterations in the hypothalamic Kiss1 system. Further studies are needed to clarify the mechanisms involved in these changes in reproductive function.

Topics: Animals; Animals, Newborn; Body Weight; Disorders of Sex Development; Fasting; Female; Gene Expression Regulation, Developmental; Kisspeptins; Leptin; Luteinizing Hormone; Male; Malnutrition; Neuropeptide Y; Organ Size; Pregnancy; Pregnancy Complications; Pro-Opiomelanocortin; Rats; Rats, Wistar; Receptors, Leptin; Testis; Testosterone

Hyperandrogenism, disturbance of the hypothalamus-pituitary-ovary axis followed by elevated serum luteinizing hormone (LH) levels, and insulin resistance are involved in the complicated pathophysiology of polycystic ovary syndrome (PCOS). Kisspeptin is coexpressed with neurokinin B (NKB) in the arcuate nucleus (ARC), the center of the gonadotropin-releasing hormone pulse generator that is responsible for pulsatile LH secretion. We compared 2 androgenized rat models of PCOS to evaluate the estrous cycle, hormonal profiles, and expression of kisspeptin and NKB in the ARC. Rats in our postnatal dihydrotestosterone (DHT)-treatment model exhibited weight gain and persistent diestrus with normal LH levels. In contrast, irregular cycles, with elevated LH serum levels and normal body weight, were found in the prenatally DHT-treated rats. We also found increased signals of kisspeptin and NKB in the ARC of the prenatally DHT-treated rats, and not in the postnatally DHT-treated rats. Our results suggest that prenatal exposure to androgens may result in higher kisspeptin and NKB levels in the ARC, which could be associated with 1 phenotype of PCOS that is characterized by normal body weight and higher LH secretion, whereas in postnatally DHT-treated rats, characteristics such as weight gain and normal LH levels are seen in the obese PCOS phenotype.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dihydrotestosterone; Disease Models, Animal; Estrous Cycle; Female; Gonadal Steroid Hormones; Gonadotropins; Hypothalamo-Hypophyseal System; Hypothalamus, Anterior; Kisspeptins; Ovary; Phenotype; Polycystic Ovary Syndrome; Rats, Wistar

In the human infundibular (arcuate) nucleus, a subpopulation of neurons coexpress kisspeptin and neurokinin B (NKB), 2 peptides required for normal reproductive function. A homologous group of neurons exists in the arcuate nucleus of rodents, termed KNDy neurons based on the coexpression of kisspeptin, NKB, and dynorphin. To study their function, we recently developed a method to selectively ablate KNDy neurons using NK3-SAP, a neurokinin 3 receptor agonist conjugated to saporin (SAP). Here, we ablated KNDy neurons in female rats to determine whether these neurons are required for estrous cyclicity and the steroid induced LH surge. NK3-SAP or Blank-SAP (control) was microinjected into the arcuate nucleus using stereotaxic surgery. After monitoring vaginal smears for 3-4 weeks, rats were ovariectomized and given 17β-estradiol and progesterone in a regimen that induced an afternoon LH surge. Rats were killed at the time of peak LH levels, and brains were harvested for NKB and dual labeled GnRH/Fos immunohistochemistry. In ovary-intact rats, ablation of KNDy neurons resulted in hypogonadotropic hypogonadism, characterized by low levels of serum LH, constant diestrus, ovarian atrophy with increased follicular atresia, and uterine atrophy. Surprisingly, the 17β-estradiol and progesterone-induced LH surge was 3 times higher in KNDy-ablated rats. Despite the marked increase in the magnitude of the LH surge, the number of GnRH or anterior ventral periventricular nucleus neurons expressing Fos was not significantly different between groups. Our studies show that KNDy neurons are essential for tonic levels of serum LH and estrous cyclicity and may play a role in limiting the magnitude of the LH surge.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dynorphins; Estradiol; Estrous Cycle; Female; Hypogonadism; Kisspeptins; Luteinizing Hormone; Neurokinin B; Neurons; Progesterone; Rats; Rats, Sprague-Dawley

Jerboa (Jaculus orientalis) is a semi-desert rodent displaying strong seasonal variations in biological functions in order to survive harsh conditions. When environmental conditions become unfavorable in early autumn, it shuts down its reproductive axis, increases its body weight, and finally hibernates. In spring, the jerboa displays opposite regulations, with a reactivation of reproduction and reduction in body weight. This study investigated how genes coding for different hypothalamic peptides involved in the central control of reproduction (Rfrp and Kiss1) and energy homeostasis (Pomc, Npy, and Somatostatin) are regulated according to seasons in male jerboas captured in the wild in spring or autumn. Remarkably, a coordinated increase in the mRNA level of Rfrp in the dorso/ventromedial hypothalamus and Kiss1, Pomc, and Somatostatin in the arcuate nucleus was observed in jerboas captured in spring as compared to autumn animals. Only Npy gene expression in the arcuate nucleus displayed no significant variations between the two seasons. These variations appear in line with the jerboa's seasonal physiology, since the spring increase in Rfrp and Kiss1 expression might be related to sexual reactivation, while the spring increase in genes encoding anorexigenic peptides, POMC, and somatostatin may account for the reduced body weight reported at this time of the year. J. Comp. Neurol. 524:3717-3728, 2016. © 2016 Wiley Periodicals, Inc.

Topics: Animals; Biological Clocks; Body Weight; Gene Expression Regulation; Hypothalamus; In Situ Hybridization; Kisspeptins; Male; Neurons; Neuropeptide Y; Neuropeptides; Organ Size; Pro-Opiomelanocortin; Reproduction; RNA, Messenger; Rodentia; Seasons; Somatostatin; Testis

Selective estrogen receptor modulators (SERMs) are a class of therapeutic chemicals which present tissue-specific estrogen receptor modulating activity. Neonatal exposure to SERMs has been reported to adversely affect central nervous system development, however, mechanism and involvement of hypothalamic kisspeptin neurone in this impairment remains undetermined. To clarify this uncertainty, neonates from female Donryu rats were subcutaneously injected with raloxifene (RLX) at 0.1, 1, and 10mg/kg or tamoxifen (TMX) at 10mg/kg on postnatal day 0, and then hypothalamic KiSS1 mRNA expression and gonadotropin levels were investigated during young adulthood and estrous cycling was monitored until middle age. Treatment with RLX or TMX at 10mg/kg significantly depressed luteinizing hormone surge levels and KiSS1 mRNA expression in the anteroventral periventricular nucleus (AVPV), the control center of estrous cyclicity. The 10mg/kg TMX group also showed decreased levels of follicle-stimulating hormone and KiSS1 mRNA expression in the arcuate nucleus (ARC). Early cessation of normal estrous cycling was observed in the 10mg/kg RLX group, while the estrous cycle in the 10mg/kg TMX group had ceased by the start of the analysis. The same dose of tamoxifen or raloxifene had either weak-estrogenic or anti-estrogenic activity on the uterus, respectively; however, treatment in adulthood with both SERMs did not affect KiSS1 mRNA expression in either the AVPV or ARC in the present study. These results indicate that neonatal exposure to SERMs could disrupt neuroendocrine development and postnatal reproductive function through the alteration of kisspeptin neurons.

Topics: Age Factors; Animals; Animals, Newborn; Body Weight; Developmental Disabilities; Disease Models, Animal; Endocrine System Diseases; Estradiol; Estrous Cycle; Female; Hormones; Hypothalamus; Kisspeptins; Neurons; Ovariectomy; Pregnancy; Progesterone; Raloxifene Hydrochloride; Rats; Selective Estrogen Receptor Modulators; Tamoxifen

Arcuate neurons that coexpress kisspeptin (Kiss1), neurokinin B (Tac2), and dynorphin (Pdyn) mediate negative feedback of 17β-estradiol (E2) on the HPG axis. Previous studies report that fasting and caloric restriction reduce arcuate Kiss1 expression. The objective of this study was to determine the interactions of E2 with fasting, caloric restriction, and diet-induced obesity on KNDy gene and receptor expression. Ovariectomized female mice were separated into control and estradiol benzoate (E2B)-treated groups. E2B decreased Kiss1 and the tachykinin 2 receptor, Tac3r, in ARC tissue and Tac2 in Tac2 neurons. Diet-induced obesity decreased Kiss1 in oil-treated animals and the kisspeptin receptor, Kiss1r and Tac3r in the ARC of E2B-treated animals. Chronic caloric (30%) restriction reduced all three neuropeptides in oil-treated females and Kiss1r by E2B in CR animals. Taken together, our experiments suggest that steroidal environment and energy state negatively regulate KNDy gene expression in both ARC and Tac2 neurons.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Composition; Body Weight; Caloric Restriction; Diet; Diet, High-Fat; Dynorphins; Estradiol; Fasting; Female; Gene Expression Profiling; Gene Expression Regulation; Ghrelin; Kisspeptins; Mice, Inbred C57BL; Models, Biological; Neurokinin B; Neurons; Neuropeptides; Obesity; Organ Size; Signal Transduction

A temporary and reversible inhibition of the hypothalamo-pituitary-gonadal axis is adaptive when energy reserves are diminished, allowing individual survival and energy accumulation for eventual reproduction. The AMP-activated protein kinase (AMPK) works as a cellular sensor of the AMP to ATP ratio and ultimately of energy availability. Activation of AMPK suppresses ATP-consuming processes and stimulates ATP-producing pathways. The AMPK α2 catalytic subunit is expressed in multiple hypothalamic nuclei including those associated with reproductive control, ie, the anteroventral periventricular nucleus and the arcuate nucleus. Subsets of kisspeptin neurons in the anteroventral periventricular nucleus (20% in females) and arcuate nucleus (45% in males and 65% in females) coexpress AMPKα2 mRNA. Using the Cre-loxP approach, we assessed whether AMPKα2 in Kiss1 cells is required for body weight and reproductive function. The AMPKα2-deleted mice show no difference in body weight and time for sexual maturation compared with controls. Males and females are fertile and have normal litter size. The AMPKα2-deleted and control females have similar estradiol feedback responses and show no difference in Kiss1 mRNA expression after ovariectomy or ovariectomy plus estradiol replacement. In males, acute fasting decreased Kiss1 mRNA expression in both groups, but no effect was observed in females. However, after an acute fasting, control mice displayed prolonged diestrous phase, but AMPKα2-deleted females showed no disruption of estrous cycles. Our findings demonstrate that the AMPKα2 catalytic subunit in Kiss1 cells is dispensable for body weight and reproductive function in mice but is necessary for the reproductive adaptations to conditions of acute metabolic distress.

Topics: AMP-Activated Protein Kinases; Animals; Body Weight; Estrous Cycle; Fasting; Female; Hypothalamus; Kisspeptins; Male; Mice; Mice, Knockout; Neurons; Sexual Maturation

Puberty is governed by the secretion of gonadotropin releasing hormone (GnRH), but the roles and identities of upstream neuropeptides that control and time puberty remain poorly understood. Indeed, how various reproductive neural gene systems change before and during puberty, and in relation to one another, is not well-characterized. We detailed the daily pubertal profile (from postnatal day [PND] 15 to PND 30) of neural Kiss1 (encoding kisspeptin), Kiss1r (kisspeptin receptor), Tac2 (neurokinin B), and Rfrp (RFRP-3, mammalian GnIH) gene expression and day-to-day c-fos induction in each of these cell types in developing female mice. Kiss1 expression in the AVPV/PeN increased substantially over the pubertal transition, reaching adult levels around vaginal opening (PND 27.5), a pubertal marker. However, AVPV/PeN Kiss1 neurons were not highly activated, as measured by c-fos co-expression, at any pubertal age. In the ARC, Kiss1 and Tac2 cell numbers showed moderate increases across the pubertal period, and neuronal activation of Tac2/Kiss1 cells was moderately elevated at all pubertal ages. Additionally, Kiss1r expression specifically in GnRH neurons was already maximal by PND 15 and did not change with puberty. Conversely, both Rfrp expression and Rfrp/c-fos co-expression in the DMN decreased markedly in the early pre-pubertal stage. This robust decrease of the inhibitory RFRP-3 population may diminish inhibition of GnRH neurons during early puberty. Collectively, our data identify the precise timing of important developmental changes - and in some cases, lack thereof - in gene expression and neuronal activation of key reproductive neuropeptides during puberty, with several changes occurring well before vaginal opening.

Topics: Animals; Body Weight; Brain; Female; Gene Expression Regulation, Developmental; Gonadotropin-Releasing Hormone; Kisspeptins; Mice; Mice, Inbred C57BL; Neurons; Neuropeptides; Protein Precursors; Proto-Oncogene Proteins c-fos; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Sexual Maturation; Tachykinins

The aim of this study was to determine the modulatory effects of peptide 234 (p234) (an antagonist of GPR54 receptors) on kisspeptin and RF9 (an RFamide-related peptide antagonist)-induced changes in reproductive functions and energy balance in female rats. Female Sprague-Dawley rats were weaned on postnatal day (pnd) 21. The animals were intracerebroventricularly cannulated under general anesthesia on pnd 23. Groups of female rats were injected with kisspeptin, RF9, p234, kisspeptin plus p234, or RF9 plus p234, daily. The experiments were ended on the day of first diestrus following pnd 60. Kisspeptin or RF9 alone advanced vaginal opening (VO), which was delayed by administration of kisspeptin antagonist alone. In the rats given kisspeptin plus p234 or RF9 plus p234, VO was not different from control rats. Kisspeptin and RF9 elicited significant elevations in circulating LH levels. Coadministrations of kisspeptin or RF9 with p234 decreased LH levels significantly. The use of p234 alone did not cause any significant change in LH secretion. Kisspeptin decreased both food intake and body weight while RF9 decreased only food intake without affecting body weight. The effects of kisspeptin on energy balance were also reversed by central administration of p234. In conclusion, kisspeptin antagonist, p234, modulates the effects of kisspeptin on reproductive functions and energy balance, whereas RF9 seems to exert only its effects on reproductive functions by means of GPR54 signaling in female rats.

Topics: Animals; Body Weight; Energy Metabolism; Female; Kisspeptins; Luteinizing Hormone; Neuropeptides; Peptides; Rats; Rats, Sprague-Dawley; Reproduction; Sexual Maturation

Prenatal undernutrition and postnatal overnutrition increase the risk of some metabolic disorders in adulthood, and hypothalamic leptin resistance makes an important contribution to these effects. Leptin plays important roles in the maintenance of reproductive function, and its actions might be partially mediated by kisspeptin, which is a potent positive regulator of gonadotropin-releasing hormone. In this study, the effects of prenatal undernutrition and postnatal overnutrition on reproductive parameters and sexual maturation during the peripubertal period were evaluated. Rats subjected to prenatal undernutrition (IUGR) and fed a postnatal high-fat diet (HFD) (n = 7) exhibited 40% higher serum leptin levels and 30% lower hypothalamic Kiss1 (the gene encoding kisspeptin) mRNA levels than those subjected to prenatal undernutrition (IUGR) and fed a normal diet (n = 7). No such HFD-induced postnatal alterations were observed in the rats fed a normal diet during the prenatal period (control) (n = 7 per group). Although the consumption of the HFD did not affect the serum luteinizing hormone levels or body weight of the IUGR or control rats, it did promote vaginal opening in both groups (evaluated in 14 rats per group). These findings indicate that hypothalamic leptin resistance might occur in IUGR-HFD rats, but these changes do not influence downstream effectors of the reproductive endocrinological system. They also suggest that the relationships between nutritional conditions, body weight, reproductive factors, and sexual maturation are complex.

Topics: Animals; Animals, Newborn; Body Weight; Female; Gonadotropin-Releasing Hormone; Hypothalamus; Kisspeptins; Leptin; Male; Malnutrition; Neuropeptides; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Receptors, Neuropeptide; RNA, Messenger

The timing of puberty and subsequent fertility in female mammals are dependent on the integration of metabolic signals by the hypothalamus. Pro-opiomelanocortin (POMC) neurones in the arcuate nucleus (ARC) comprise a critical metabolic-sensing pathway controlling the reproductive neuroendocrine axis. α-Melanocyte-stimulating hormone (αMSH), a product of the POMC gene, has excitatory effects on gonadotrophin-releasing hormone (GnRH) neurones and fibres containing αMSH project to GnRH and kisspeptin neurones. Because kisspeptin is a potent stimulator of GnRH release, αMSH may also stimulate GnRH secretion indirectly via kisspeptin neurones. In the present work, we report studies conducted in young female cattle (heifers) aiming to determine whether increased nutrient intake during the juvenile period (4-8 months of age), a strategy previously shown to advance puberty, alters POMC and KISS1 mRNA expression, as well as αMSH close contacts on GnRH and kisspeptin neurones. In Experiment 1, POMC mRNA expression, detected by in situ hybridisation, was greater (P < 0.05) in the ARC in heifers that gained 1 kg/day of body weight (high-gain, HG; n = 6) compared to heifers that gained 0.5 kg/day (low-gain, LG; n = 5). The number of KISS1-expressing cells in the middle ARC was reduced (P < 0.05) in HG compared to LG heifers. In Experiment 2, double-immunofluorescence showed limited αMSH-positive close contacts on GnRH neurones, and the magnitude of these inputs was not influenced by nutritional status. Conversely, a large number of kisspeptin-immunoreactive cells in the ARC were observed in close proximity to αMSH-containing varicosities. Furthermore, HG heifers (n = 5) exhibited a greater (P < 0.05) percentage of kisspeptin neurones in direct apposition to αMSH fibres and an increased (P < 0.05) number of αMSH close contacts per kisspeptin cell compared to LG heifers (n = 6). These results indicate that the POMC-kisspeptin pathway may be important in mediating the nutritional acceleration of puberty in heifers.

Topics: alpha-MSH; Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Cattle; Cell Count; Female; Gonadotropin-Releasing Hormone; Hypothalamus; Kisspeptins; Molecular Sequence Data; Neurons; Nutritional Status; Preoptic Area; Pro-Opiomelanocortin; Sexual Maturation

Neonatal exposure to estrogens is known to cause delayed effects, a late-occurring adverse effect on adult female reproductive functions, such as early onset of age-matched abnormal estrous cycling. However, the critical period in which neonates are sensitive to delayed effects inducible by exogenous estrogen exposure has not been clearly identified. To clarify this window, we examined the intensity and timing of delayed effects using rats exposed to ethynylestradiol (EE) at various postnatal ages. After subcutaneous administration of a single dose of EE (20 μg/kg, which induces delayed effects) on Postnatal Day (PND) 0, 5, 10, or 14 in Wistar rats, hypothalamic and hormonal alterations in young adults and long-term estrous cycling status were investigated as indicators of delayed effects. In young adults, peak luteinizing hormone concentrations at the time of the luteinizing hormone surge showed a decreasing trend, and KiSS1 mRNA expression of the anterior hypothalamus and number of KiSS1-positive cells in the anteroventral periventricular nucleus were significantly decreased in the PND 0, 5, and 10 groups. The reduction in KiSS1 mRNA and KiSS1-postive cells was inversely correlated with age at time of exposure. These groups also exhibited early onset of abnormal estrous cycling, starting from 17 wk of age in the PND0 group and 19 wk of age in the PND5 and 10 groups. These indicators were not apparent in the PND14 group. Our results suggest that PND0-PND10 is the critical window of susceptibility for delayed effects, and PND14 is presumed to be the provisional endpoint of the window.

Topics: Aging; Animals; Animals, Newborn; Body Weight; Estrous Cycle; Ethinyl Estradiol; Female; Follicle Stimulating Hormone; Hypothalamus; Hypothalamus, Anterior; Kisspeptins; Luteinizing Hormone; Pregnancy; Prenatal Exposure Delayed Effects; Rats; Rats, Wistar; RNA, Messenger; Sex Differentiation; Vagina; Vaginal Diseases

Reproduction is sensitive to insufficient body energy reserves, especially in females. Metabolic regulation of the male reproductive axis is less obvious, and the impact of conditions of persistent energy excess has received moderate attention. Yet, the escalating prevalence of obesity and the clinical evidence of its deleterious effects on male fertility have raised considerable concerns. We report here phenotypic and mechanistic studies of the reproductive impact of postnatal nutritional manipulations (mainly overnutrition) coupled to a high-fat diet (HFD) after weaning. Metabolic and hormonal analyses in young (4 months old) and middle-aged (10 months old) animals revealed that HFD caused profound metabolic perturbations, including glucose intolerance, which were worsened by precedent postnatal overfeeding; these were detectable already in young males but aggravated in 10-month-old rats. Impairment of reproductive parameters took place progressively, and HFD alone was sufficient to explain most of these alterations, regardless of postnatal under- or overnutrition. In young males, testosterone (T) levels and steroidogenic enzyme expression were suppressed by HFD, without compensatory increases of LH levels, which were in fact partially inhibited in heavier males. In addition, obese males displayed suppressed hypothalamic Kiss1 expression despite low T, and HFD inhibited LH responses to kisspeptin. Overweight anticipated some of the neuroendocrine effects of aging, such as the suppression of hypothalamic Kiss1 expression and the decline in serum T and LH levels. Nonetheless, HFD per se caused a detectable worsening of key reproductive indices in middle-aged males, such as basal LH and FSH levels as well as LH responses to kisspeptin. Our study demonstrates that nutritional stress, especially HFD, has a profound deleterious impact on metabolic and gonadotropic function as well as on the Kiss1 system and precipitates neuroendocrine reproductive senescence in the male.

Topics: Animals; Body Weight; Diet, High-Fat; Gene Expression Regulation; Glucose Tolerance Test; Hypogonadism; Hypothalamus; In Situ Hybridization; Kisspeptins; Luteinizing Hormone; Male; Neurosecretory Systems; Obesity; Phenotype; Rats; Rats, Wistar; Reproduction; Sex Factors; Testosterone; Time Factors

The neuropeptide kisspeptin regulates reproduction by stimulating gonadotropin-releasing hormone (GnRH) neurons via the kisspeptin receptor KISS1R. In addition to GnRH neurons, KISS1R is expressed in other brain areas and peripheral tissues, which suggests that kisspeptin has additional functions beyond reproduction. Here, we studied the energetic and metabolic phenotype in mice lacking kisspeptin signaling (Kiss1r KO mice). Compared with WT littermates, adult Kiss1r KO females displayed dramatically higher BW, leptin levels, and adiposity, along with strikingly impaired glucose tolerance. Conversely, male Kiss1r KO mice had normal BW and glucose regulation. Surprisingly, despite their obesity, Kiss1r KO females ate less than WT females; however, Kiss1r KO females displayed markedly reduced locomotor activity, respiratory rate, and energy expenditure, which were not due to impaired thyroid hormone secretion. The BW and metabolic phenotype in Kiss1r KO females was not solely reflective of absent gonadal estrogen, as chronically ovariectomized Kiss1r KO females developed obesity, hyperleptinemia, reduced metabolism, and glucose intolerance compared with ovariectomized WT females. Our findings demonstrate that in addition to reproduction, kisspeptin signaling influences BW, energy expenditure, and glucose homeostasis in a sexually dimorphic and partially sex steroid-independent manner; therefore, alterations in kisspeptin signaling might contribute, directly or indirectly, to some facets of human obesity, diabetes, or metabolic dysfunction.

Topics: Animals; Body Weight; Energy Metabolism; Female; Glucose Intolerance; Humans; Kisspeptins; Male; Mice; Mice, 129 Strain; Mice, Inbred C57BL; Mice, Knockout; Motor Activity; Obesity; Ovariectomy; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Signal Transduction

Animals living in temperate zones anticipate seasonal environmental changes to adapt their biological functions, especially reproduction and metabolism. Two main physiological mechanisms have evolved for this adaptation: intrinsic long-term timing mechanisms with an oscillating period of approximately 1 year, driven by a circannual clock [1], and synchronization of biological rhythms to the sidereal year using day length (photoperiod) [2]. In mammals, the pineal hormone melatonin relays photoperiodic information to the hypothalamus to control seasonal physiology through well-defined mechanisms [3-6]. In contrast, little is known about how the circannual clock drives endogenous changes in seasonal functions. The aim of this study was to determine whether genes involved in photoperiodic time measurement (TSHβ and Dio2) and central control of reproduction (Rfrp and Kiss1) display circannual rhythms in expression under constant conditions. Male European hamsters, deprived of seasonal time cues by pinealectomy and maintenance in constant photoperiod, were selected when expressing a subjective summer or subjective winter state in their circannual cycle of body weight, temperature, and testicular size. TSHβ expression in the pars tuberalis (PT) displayed a robust circannual variation with highest level in the subjective summer state, which was positively correlated with hypothalamic Dio2 and Rfrp expression. The negative sex steroid feedback was found to act specifically on arcuate Kiss1 expression. Our findings reveal TSH as a circannual output of the PT, which in turn regulates hypothalamic neurons controlling reproductive activity. Therefore, both the circannual and the melatonin signals converge on PT TSHβ expression to synchronize seasonal biological activity.

Topics: Adaptation, Biological; Animals; Biological Clocks; Body Temperature; Body Weight; Cricetinae; Gene Expression Regulation; Kisspeptins; Male; Organ Size; Photoperiod; Pituitary Gland, Anterior; Reproduction; Seasons; Testis; Thyrotropin, beta Subunit

Female reproductive health is noticeably compromised by obesity. The underlying mechanisms remain to be elucidated. Accumulating evidence indicates that the expression level of ovarian Kiss1 peaks in the afternoon during prooestrus, suggesting local regulatory roles for Kiss1 in the ovulatory process. We used a diet-induced model of obesity to evaluate whether the ovarian Kiss1 system is affected by obesity, and, to investigate the association of the Kiss1 system with ovulatory disorders in female rats.. Post-weaning, female, Sprague-Dawley rats were randomly fed either a high-fat diet (HFD) or a normal chow diet (NCD) until they reached postnatal day 30 (PND 30), PND 42, or PND 70. The timing of vaginal opening was recorded, and oestrous cyclicity was monitored for 2 consecutive weeks immediately post puberty and again at 8-9 weeks of age. Tissues from the left ovary were collected for determination of the levels of Kiss1 and G protein-coupled receptor 54 (GPR54) mRNA, and tissues from the right ovary were collected for assessment of the immunoreactivity (IR) of the corresponding protein products, kisspeptin and GPR54.. The high-fat diet resulted in a significantly higher body weight and an earlier puberty onset. Oestrous cyclicity was disrupted by the HFD with significant reductions in the expression of ovulation-related genes. A marked suppression of ovarian Kiss1 mRNA levels was observed during prooestrus and oestrus at PND 42, and, during prooestrus, oestrus, and metoestrus at PND 70 in the HFD rats compared with the NCD controls. In the HFD group, the immunoreactivity of kisspeptin was significantly lower in theca cells from antral follicles during prooestrus and oestrus at PND 42, and, during prooestrus, oestrus at PND 70. At the prooestrus stage, in the HFD group the immunoreactivity of kisspeptin was also lower in the theca cells of preovulatory follicles at both PND 42 and PND 70.. Exposure of female rats to an post-weaning, high-fat diet has long-term deleterious effects on ovulation, that may involve down-regulation of ovarian Kiss1 mRNA and kisspeptin.

Topics: Animals; Body Weight; Diet, High-Fat; Estrous Cycle; Female; Gene Expression; Immunohistochemistry; Kisspeptins; Ovarian Follicle; Ovary; Ovulation; Random Allocation; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Receptors, Kisspeptin-1; Reverse Transcriptase Polymerase Chain Reaction; Sexual Maturation; Theca Cells; Time Factors; Weaning

In naked mole-rat (NMR) colonies, breeding is monopolized by the queen and her consorts. Subordinates experience gonadal development if separated from the queen. To elucidate the neuroendocrine factors underlying reproductive suppression/development in NMRs, we quantified plasma gonadal steroids and GnRH-1- and kisspeptin-immunoreactive (ir) neurons in subordinate adults and in those allowed to develop into breeders, with or without subsequent gonadectomy. In males and females, respectively, plasma testosterone and progesterone are higher in breeders than in subordinates. No such distinction occurs for plasma estradiol; its presence after gonadectomy and its positive correlation with adrenal estradiol suggest an adrenal source. Numbers of GnRH-1-ir cell bodies do not differ between gonad-intact breeders and subordinates within or between the sexes. As in phylogenetically related guinea pigs, kisspeptin-ir processes pervade the internal and external zones of the median eminence. Their distribution is consistent with actions on GnRH-1 neurons at perikaryal and/or terminal levels. In previously investigated species, numbers of kisspeptin-ir cell bodies vary from substantial to negligible according to sex and/or reproductive state. NMRs are exceptional: irrespective of sex, reproductive state, or presence of gonads, substantial numbers of kisspeptin-ir cell bodies are detected in the rostral periventricular region of the third ventricle (RP3V) and in the anterior periventricular (PVa), arcuate, and dorsomedial hypothalamic nuclei. Nevertheless, the greater number in the RP3V/PVa of female breeders compared with female subordinates or male breeders suggests that emergence from a hypogonadotrophic state in females may involve kisspeptin-related mechanisms similar to those underlying puberty or seasonal breeding in other species.

Topics: Animals; Body Weight; Brain; Castration; Cell Count; Cooperative Behavior; Estradiol; Female; Kisspeptins; Male; Mole Rats; Neurons; Progesterone; Radioimmunoassay; Receptors, LHRH; Sexual Behavior, Animal; Testosterone

In mammals, melatonin is the pivotal messenger synchronizing biological functions, notably reproductive activity, with annual daylength changes. Recently, two major findings clarified melatonin's mode of action. First, melatonin controls the production of thyroid stimulating hormone (TSH) by the pars tuberalis of the adenohypophysis. This TSH regulates local thyroid hormone availability in the mediobasal hypothalamus. Second, the RF-amides kisspeptin and RFRP-3, recently discovered regulators of the gonadotropic axis, are involved in the melatonin control of reproduction. This study aims to establish a mechanistic link between the melatonin-driven TSH and the RF-amide control of reproduction. We treated short-day-adapted male Djungarian and Syrian hamsters with a chronic central infusion of TSH. In both hamster species, the central administration of 5 mIU/d TSH for 4 to 6 wk restored the summer phenotype of both testicular activity and kisspeptin and RFRP expression. Vehicle treated hamsters remain sexually inactive. Furthermore, the TSH treatment increased the body weight of lean short-day-adapted Djungarian hamsters and reduced hypothalamic somatostatin expression to the summer phenotype. In summary, our study demonstrates the pivotal role of melatonin-driven TSH for the seasonal regulation of reproduction and body weight, and uncovers the neuropeptides relaying this signal within the hypothalamus.

Topics: Animals; Body Weight; Cricetinae; Female; Gene Expression; Hypothalamus; Immunohistochemistry; In Situ Hybridization; Infusions, Intraventricular; Iodide Peroxidase; Kisspeptins; Male; Melatonin; Mesocricetus; Neuropeptides; Phodopus; Photoperiod; Receptors, Thyrotropin; Seasons; Somatostatin; Species Specificity; Testis; Thyrotropin; Time Factors

Siberian hamsters (Phodopus sungorus) exhibit robust seasonal rhythms of reproduction driven by changes in day length. Day length is encoded endogenously by the duration of nocturnal melatonin (Mel) secretion from the pineal gland. Short duration Mel signals stimulate whereas long duration Mel signals inhibit reproduction. The mechanism by which Mel regulates the reproductive axis has not been fully characterized. In Siberian hamsters, the thyroid hormone triiodothyronine (T₃) is thought to be part of the photoperiodic mechanism. The availability of T₃ is decreased in hamsters housed in short day lengths, and injections of exogenous T₃ stimulate testicular growth in short-day (SD) Siberian hamsters. Thus, T₃ acts as a neuroendocrine intermediate between the Mel rhythm and the reproductive axis. The RFamides kisspeptin (Kiss1) and gonadotropin-inhibitory hormone (GnIH) also act as a link between the Mel rhythm and the reproductive axis. Expression of both of these neuropeptides is regulated by photoperiod and Mel. Kiss1 stimulates, and GnIH inhibits, the reproductive axis in long-day housed hamsters. It remains unknown whether T₃ acts through changes in RFamide expression in the regulation of reproduction or whether these molecules act independently of one another. We tested the hypothesis that exogenous T₃ administered to SD hamsters, a treatment that stimulates testicular growth, would also result in alterations in the patterns of Kiss1- and GnIH-immunoreactivity. Administration of T₃ to SD hamsters resulted in significant testicular growth as well as a long day-like pattern of RFamide peptide expression. Thus, exogenous T₃ elicited increased numbers of Kiss1-positive cells in the hypothalamic anteroventral periventricular nucleus, decreased numbers of Kiss1-positive cells in the arcuate nucleus, and a greater number of GnIH-positive cells in the dorsomedial hypothalamus compared with SD controls. The results are consistent with the hypothesis that T₃ elicits alterations in the reproductive axis through alterations in RFamide peptide expression.

Topics: Analysis of Variance; Animals; Body Weight; Brain Chemistry; Circadian Rhythm; Cricetinae; Glycoproteins; Immunohistochemistry; Kisspeptins; Male; Organ Size; Phodopus; Reproduction; Testis; Triiodothyronine

The perinatal nutritional environment can permanently influence body weight, potentially leading to changes in puberty onset and reproductive function. We hypothesized that perinatal under- or overfeeding would alter puberty onset and influence concentrations of a neuropeptide crucial for successful puberty, kisspeptin. We manipulated Wistar rat litter sizes to derive small (SL), control (CL), and large (LL) litters containing 4, 12, and 20 rat pups respectively. This manipulation results in an overweight phenotype in SL rats and a lean phenotype in LL that persists throughout life. To investigate whether successful puberty onset is affected by neonatal under- or overfeeding, we examined indices of growth and development, including the onset of puberty, as well as the central expression of Kiss1 mRNA in these pups. Male LL rats reached puberty later than those from CL. These males also had reduced plasma testosterone and elevated 17beta-estradiol concentrations at puberty. The age at puberty onset was not affected in SL males despite accelerated growth. In females, puberty onset was not significantly delayed by having a lean phenotype, and steroid hormones were not affected. The age at onset was, however, younger in the SL females. Kiss1 mRNA in the hypothalamus was not affected by neonatal nutrition either at puberty or 7 days later. Our findings show early life underfeeding in males and overfeeding in females significantly affects puberty onset, altering steroid hormone concentrations in males, but this is not related to changes in hypothalamic kisspeptin.

Topics: Animals; Body Weight; Estradiol; Female; Hypothalamus; Kisspeptins; Male; Malnutrition; Overnutrition; Rats; Rats, Wistar; Sexual Maturation; Testosterone; Weaning

Estrogen withdrawal increases gonadotropin secretion and body weight, but the critical cell populations mediating these effects are not well understood. Recent studies have focused on a subpopulation of hypothalamic arcuate neurons that coexpress estrogen receptor α, neurokinin 3 receptor (NK(3)R), kisspeptin, neurokinin B, and dynorphin for the regulation of reproduction. To investigate the function of kisspeptin/neurokinin B/dynorphin (KNDy) neurons, a novel method was developed to ablate these cells using a selective NK(3)R agonist conjugated to the ribosome-inactivating toxin, saporin (NK(3)-SAP). Stereotaxic injections of NK(3)-SAP in the arcuate nucleus ablated KNDy neurons, as demonstrated by the near-complete loss of NK(3)R, NKB, and kisspeptin-immunoreactive (ir) neurons and depletion of the majority of arcuate dynorphin-ir neurons. Selectivity was demonstrated by the preservation of proopiomelanocortin, neuropeptide Y, and GnRH-ir elements in the arcuate nucleus and median eminence. In control rats, ovariectomy (OVX) markedly increased serum LH, FSH, and body weight, and these parameters were subsequently decreased by treatment with 17β-estradiol. KNDy neuron ablation prevented the rise in serum LH after OVX and attenuated the rise in serum FSH. KNDy neuron ablation did not completely block the suppressive effects of E(2) on gonadotropin secretion, a finding consistent with redundant pathways for estrogen negative feedback. However, regardless of estrogen status, KNDy-ablated rats had lower levels of serum gonadotropins compared with controls. Surprisingly, KNDy neuron ablation prevented the dramatic effects of OVX and 17β-estradiol (E(2)) replacement on body weight and abdominal girth. These data provide evidence that arcuate KNDy neurons are essential for tonic gonadotropin secretion, the rise in LH after removal of E(2), and the E(2) modulation of body weight.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dynorphins; Estradiol; Estrogens; Female; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Gonadotropins; Immunohistochemistry; Immunotoxins; Kisspeptins; Luteinizing Hormone; Neurokinin B; Neurons; Neuropeptide Y; Ovariectomy; Pro-Opiomelanocortin; Rats; Rats, Sprague-Dawley; Ribosome Inactivating Proteins, Type 1; Saporins

Hypothalamic neurons, which produce the kisspeptin family of peptide hormones (Kp), are critical for initiating puberty and maintaining estrous cyclicity by stimulating gonadotropin-releasing hormone (GnRH) release. Conversely, RFamide-related peptide-3 (RFRP3) neurons inhibit GnRH activity. It has previously been shown that neonatal exposure to bisphenol A (BPA) can alter the timing of female pubertal onset and induce irregular estrous cycles or premature anestrus. Here we tested the hypothesis that disrupted ontogeny of RFamide signaling pathways may be a mechanism underlying advanced puberty. To test this, we used a transgenic strain of Wistar rats whose GnRH neurons express enhanced green fluorescent protein. Pups were exposed by daily subcutaneous injection to vehicle, 17beta-estradiol (E2), 50 μg/kg BPA, or 50 mg/kg BPA, from Postnatal Day (PND) 0 through PND 3, and then cohorts were euthanized on PNDs 17, 21, 24, 28, and 33 (5-8 animals per age per exposure; males were collected on PNDs 21 and 33). Vaginal opening was advanced by E2 and 50 μg/kg BPA. On PND 28, females exposed to E2 and 50 μg/kg BPA had decreased RFRP-3 fiber density and contacts on GnRH neurons. RFRP3 perikarya were also decreased in females exposed to 50 μg/kg BPA. Data suggest that BPA-induced premature puberty results from decreased inhibition of GnRH neurons.

Topics: Animals; Benzhydryl Compounds; Body Weight; Estrogens, Non-Steroidal; Female; Gonadotropin-Releasing Hormone; Hypothalamus; Kisspeptins; Male; Neuropeptides; Phenols; Puberty, Precocious; Rats; Rats, Transgenic; Rats, Wistar; Vagina

An intact hypothalamic kiss1/kisspeptin/kiss1r complex is a prerequisite for reproductive competence, and kisspeptin treatment could be a practical therapeutic approach to some problems of infertility. One such disorder is polycystic ovarian syndrome (PCOS), a common cause of infertility affecting more than 100 million women. A rodent model of PCOS is the prepubertal female rat treated for a prolonged period with dihydrotestosterone (DHT), which induces many of the metabolic characteristics of the syndrome. We hypothesized that hypothalamic kiss1 mRNA levels, and kisspeptin immunoreactivity (ir), would be abnormal in these rats. Prepubertal female rats were exposed to DHT for 60 days. Rats were killed in two groups: at 26 and 60 days of DHT exposure. Kiss1 mRNA was quantified in hypothalamus, pituitary, ovary and visceral adipose tissue. Separate groups of rats provided brain tissue for immunohistochemical analysis of kisspeptin-ir. At 26 days of DHT exposure, hypothalamic kiss1 mRNA was severely depleted. In contrast DHT had no effect on pituitary kiss1 expression but it significantly increased levels of kiss1 mRNA in fat (+9-fold; p<0.01) and in ovary (+3-fold; p<0.05). At 60days, kiss1 expression had reverted to normal in hypothalamus and ovary but remained elevated in fat (+4-fold; p<0.05). Immunohistochemical analysis revealed that after 26 days of exposure to DHT, kisspeptin-ir was almost completely absent in the arcuate nucleus and a large depletion in kisspeptin +ve fibers was also seen in the paraventricular nucleus, supraoptic nucleus and in the anteroventral periventricular area. At 60 days, despite restored normal levels of kiss1 mRNA, hypothalamic kisspeptin-ir remained depleted in the treated rats. In summary Kiss1 gene expression is differentially affected in various tissues by chronic exposure to dihydrotestosterone in a rat model of polycystic ovary syndrome. In hypothalamus, specifically, kiss1 mRNA, and levels of kisspeptin immunoreactivity, are significantly reduced. Since these rats exhibit many of the characteristics of polycystic ovary syndrome, we suggest that atypical kiss1 expression may contribute to the multiple tissue abnormalities observed in women with this disorder. However, and of some importance, our data do not appear to be consistent with the elevated levels of LH seen in women with PCOS; i.e. reduced levels of hypothalamic kiss1 mRNA and kisspeptin immunoreactivity observed in DHT-treated rats are unlikely to produce e

Topics: Adipose Tissue; Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dihydrotestosterone; Energy Metabolism; Female; Gonadal Steroid Hormones; Hypothalamus; Immunohistochemistry; Kisspeptins; Ovary; Pituitary Gland; Polycystic Ovary Syndrome; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; RNA, Messenger

It is increasingly accepted that alterations of the early life environment may have lasting impacts on physiological functions. In particular, epidemiological and animal studies have indicated that changes in growth and nutrition during childhood and adolescence can impair reproductive function. However, the precise biological mechanisms that underlie these programming effects of neonatal nutrition on reproduction are still poorly understood. Here, we used a mouse model of divergent litter size to investigate the effects of early postnatal overnutrition and undernutrition on the maturation of hypothalamic circuits involved in reproductive function. Neonatally undernourished females display attenuated postnatal growth associated with delayed puberty and defective development of axonal projections from the arcuate nucleus to the preoptic region. These alterations persist into adulthood and specifically affect the organization of neural projections containing kisspeptin, a key neuropeptide involved in pubertal activation and fertility. Neonatal overfeeding also perturbs the development of neural projections from the arcuate nucleus to the preoptic region, but it does not result in alterations in kisspeptin projections. These studies indicate that alterations in the early nutritional environment cause lasting and deleterious effects on the organization of neural circuits involved in the control of reproduction, and that these changes are associated with lifelong functional perturbations.

Topics: Age Factors; Animals; Animals, Newborn; Body Weight; Brain Mapping; Female; Gene Expression Regulation, Developmental; Gonadotropin-Releasing Hormone; Hypothalamus; Kisspeptins; Litter Size; Luteinizing Hormone; Male; Malnutrition; Mice; Nerve Fibers; Nerve Net; Neurokinin B; Neurons; Nutritional Status; Ovariectomy; Overnutrition; Reproduction; Sex Factors

Postnatal treatment with selective serotonin reuptake inhibitors (SSRIs) has been found to affect brain development and the regulation of reproduction in rodent models. The normal masculinization process in the brain requires a transient decrease in serotonin (5-HT) levels in the brain during the second postnatal week. Strict regulation of androgen receptor (AR) and gonadotropin-releasing hormone (GnRH) expression is important to control male reproductive activity. Therefore, this study was designed to examine the effects of a potent SSRI (citalopram) on male sexual behavior and expression levels of AR and GnRH in adult male mice receiving either vehicle or citalopram (10mg/kg) daily during postnatal days 8-21. The citalopram-treated male mice showed altered sexual behavior, specifically a significant reduction in the number of intromissions preceding ejaculation compared with the vehicle-treated mice. The citalopram-treated male mice displayed elevated anxiety-like behavior in an open field test and lower locomotor activity in their home cage during the subjective night. Although there was no change in GnRH and AR mRNA levels in the preoptic area (POA), quantified by real-time polymerase chain reaction, immunostained AR cell numbers in the medial POA were decreased in the citalopram-treated male mice. These results suggest that the early-life inhibition of 5-HT transporters alters the regulation of AR expression in the medial POA, likely causing decreased sexual behavior and altered home cage activity in the subjective night.

Topics: Animals; Animals, Newborn; Antidepressive Agents, Second-Generation; Body Weight; Citalopram; Disorders of Sex Development; Exploratory Behavior; Female; Gene Expression Regulation, Developmental; Gonadotropin-Releasing Hormone; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Motor Activity; Preoptic Area; Receptors, Androgen; Receptors, Serotonin; RNA, Messenger; Serotonin; Serotonin Plasma Membrane Transport Proteins; Sexual Behavior, Animal; Tryptophan Hydroxylase

Secretion of glucocorticoids is widely known as a key endocrine response to stresses. Prenatal dexamethasone administration induces intrauterine growth retardation and delayed onset of puberty in female rats independent of the hypothalamic Kiss1-gonadotropin-releasing hormone (GnRH) system. The aim of this study was to evaluate the influence of chronic intracerebroventricular (central, CD) or subcutaneous (peripheral, PD) dexamethasone administration to prepubertal female rats on the onset of puberty and body weight change. Rats administered dexamethasone from day 25 to day 34 (CD and PD) showed significantly reduced body weight gain throughout the experimental period and delayed onset of vaginal opening compared with rats administered saline centrally (CS) or peripherally (PS). At 34 days old, hypothalamic Kiss1r mRNA levels were significantly lower with CD than with CS. No significant differences were seen between rats administered saline and rats administered dexamethasone with regard to hypothalamic Kiss1, GnRH and NPY mRNA levels or serum LH levels. Serum leptin concentrations were higher in CD and PD than in the controls (CS and PS). These results suggest that the delayed onset of puberty induced by prepubertal dexamethasone administration occurs independent of the hypothalamic Kiss1-GnRH system.

Topics: Animals; Body Weight; Brain; Female; Glucocorticoids; Gonadotropin-Releasing Hormone; Growth; Hormones; Hypothalamus; Infusion Pumps; Kisspeptins; Organ Size; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; RNA, Messenger; Sexual Maturation; Vagina

A number of factors involved in the control of energy balance and metabolism act as modulators of gonadal axis. Ghrelin, a peptide secreted from the stomach and hypothalamus, has emerged as an orexigenic food intake controlling signal acting upon hypothalamus. Recently, the potential reproductive role of ghrelin has received great attention. This study was designed to investigate the influence of food restriction and consequent metabolic hormone (ghrelin) on the level and gene expression of female reproductive hormones in adult rats.. To study the effect of chronic food restriction on ghrelin level in adult female rats and its relation to female reproductive hormones, 32 adult female Sprague Dawley rats divided into 4 groups: Group I (control group) comprised 8 rats fed ad libitum for 30 days, Group II, III and IV (food-restricted groups for 10, 20 and 30 days respectively) each consisted of 8 rats fed 50% of ad libitum intake determined by the amount of food consumed by the control group.. Mean body weight of food restricted rats was observed to decrease during the period of the experiment. Food restriction produced significant increase of serum ghrelin with significant decrease of both gastric and hypothalamic ghrelin accompanied with significant increase in its gene expression in stomach and hypothalamus. Estradiol (E2), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels showed significant decrease correlated with down-regulation of gonadotropins, cyclin-dependent kinase (cdc2), cyclin B and kisspeptin (Kiss1) genes in food restricted rats compared with control group.. Ghrelin could be one of the hormones responsible for the suppression of female reproductive axis in case of negative energy balance. Thus, ghrelin may operate as an autocrine/paracrine regulator of ovarian function. Overall, ghrelin may represent an additional link between body weight homeostasis and reproductive function.

Topics: Animals; Body Weight; CDC2 Protein Kinase; Cyclin B; Estradiol; Female; Follicle Stimulating Hormone; Food Deprivation; Gastric Mucosa; Gene Expression Regulation; Ghrelin; Gonadotropins; Hypothalamus; Kisspeptins; Luteinizing Hormone; Ovary; Pituitary Gland; Rats; Rats, Sprague-Dawley; Serum

The hormone leptin modulates a diverse range of biological functions, including energy homeostasis and reproduction. Leptin promotes GnRH function via an indirect action on forebrain neurons. We tested whether leptin deficiency or leptin resistance due to a high-fat diet (HFD) can regulate the potent reproductive neuropeptide kisspeptin. In mice with normalized levels of estradiol, leptin deficiency markedly reduced kisspeptin gene expression, particularly in the arcuate nucleus (ARC), and kisspeptin immunoreactive cell numbers in the rostral periventricular region of the third ventricle (RP3V). The HFD model was used to determine the effects of diet-induced obesity and central leptin resistance on kisspeptin cell number and gene expression. DBA/2J mice, which are prone to HFD-induced infertility, showed a marked decrease in kisspeptin expression in both the RP3V and ARC and cell numbers in the RP3V after HFD. This is the first evidence that kisspeptin can be regulated by HFD and/or increased body weight. Next we demonstrated that leptin does not signal (via signal transducer and activator of transcription 3 or 5, or mammalian target of rapamycin) directly on kisspeptin-expressing neurons in the RP3V. Lastly, in leptin receptor-deficient mice, neither GnRH nor kisspeptin neurons were activated during a preovulatory-like GnRH/LH surge induction regime, indicating that leptin's actions on GnRH may be upstream of kisspeptin neurons. These data provide evidence that leptin's effects on reproductive function are regulated by kisspeptin neurons in both the ARC and RP3V, although in the latter site the effects are likely to be indirect.

Topics: Animals; Body Weight; Dietary Fats; Enzyme-Linked Immunosorbent Assay; Estradiol; Female; Gonadotropin-Releasing Hormone; Hypothalamus; Immunohistochemistry; Kisspeptins; Leptin; Male; Mice; Mice, Inbred C57BL; Neurons; Obesity; Proteins; Radioimmunoassay; Reverse Transcriptase Polymerase Chain Reaction; Tumor Suppressor Proteins

Based on the importance of early-life events in breast cancer risk, we have investigated the effects of high-fat diets on maturation, mammary gland development, and its susceptibility to transformation. Female Sprague-Dawley rats were fed a lowfat (LF), high corn oil (HCO), or high extra-virgin olive oil (HOO) diet from weaning and gavaged with 7,12-dimethylbenz[a]anthracene. Body weight and mass increased in the HCO group compared to the LF group. The vaginal opening was advanced in both high-fat groups, especially in the HCO group. This HCO group also had increased body weight around puberty, more corpora lutea at post-puberty, and tended to have higher kisspeptin levels in the hypothalamus. Both high-fat diets induced subtle modifications in the morphology of the mammary gland, with no changes on β-casein or hormone receptors expression in the gland. The HCO diet had a clearly stimulating effect of carcinogenesis, inducing the earliest appearance of tumors and the highest tumor incidence and yield, whereas the HOO diet seemed to have a weak enhancing effect, increasing tumor yield. Our data suggest a strong influence of the HCO diet in sexual maturation and mammary cancer risk, while rats fed the HOO diet were more similar to the controls.

Topics: 9,10-Dimethyl-1,2-benzanthracene; Amino Acid Sequence; Analysis of Variance; Animals; Body Weight; Breast; Caseins; Cell Transformation, Neoplastic; Corn Oil; Dietary Fats; Estrogen Receptor alpha; Female; Gene Expression Regulation, Neoplastic; Kisspeptins; Mammary Neoplasms, Experimental; Molecular Sequence Data; Olive Oil; Ovary; Plant Oils; Proteins; Rats; Rats, Sprague-Dawley; RNA, Messenger; Sexual Maturation

Kiss1 neurons have recently emerged as a putative conduit for the metabolic gating of reproduction, with leptin being a regulator of hypothalamic Kiss1 expression. Early perturbations of the nutritional status are known to predispose to different metabolic disorders later in life and to alter the timing of puberty; however, the potential underlying mechanisms remain poorly defined. Here we report how changes in the pattern of postnatal feeding affect the onset of puberty and evaluate key hormonal and neuropeptide [Kiss1/kisspeptin (Kp)] alterations linked to these early nutritional manipulations. Female rats were raised in litters of different sizes: small (four pups per dam: overfeeding), normal (12 pups per dam), and large litters (20 pups per litter: underfeeding). Postnatal overfeeding resulted in persistently increased body weight and earlier age of vaginal opening, as an external sign of puberty, together with higher levels of leptin and hypothalamic Kiss1 mRNA. Conversely, postnatal underfeeding caused a persistent reduction in body weight, lower ovarian and uterus weights, and delayed vaginal opening, changes that were paralleled by a decrease in leptin and Kiss1 mRNA levels. Kisspeptin-52 immunoreactivity (Kp-IR) in the hypothalamus displayed similar patterns, with lower numbers of Kp-IR neurons in the arcuate nucleus of postnatally underfed animals, and a trend for increased Kp-positive fibers in the periventricular area of early overfed rats. Yet, gonadotropin responses to Kp at puberty were similar in all groups, except for enhanced responsiveness to low doses of Kp-10 in postnatally underfed rats. In conclusion, our data document that the timing of puberty is sensitive to both overfeeding and subnutrition during early (postnatal) periods and suggest that alterations in hypothalamic expression of Kiss1/kisspeptin may underlie at least part of such programming phenomenon.

Topics: Animals; Animals, Newborn; Body Weight; Female; Hypothalamus; Kisspeptins; Leptin; Luteinizing Hormone; Maternal Behavior; Neurons; Proteins; Rats; Rats, Wistar; Sexual Maturation

Gestational exposure to the estrogenic endocrine disruptor methoxychlor (MXC) disrupts the female reproductive system at the molecular, physiological, and behavioral levels in adulthood. The current study addressed whether perinatal exposure to endocrine disruptors re-programs expression of a suite of genes expressed in the hypothalamus that control reproductive function and related these molecular changes to premature reproductive aging. Fischer rats were exposed daily for 12 consecutive days to vehicle (dimethylsulfoxide), estradiol benzoate (EB) (1 mg/kg), and MXC (low dose, 20 μg/kg or high dose, 100 mg/kg), beginning on embryonic d 19 through postnatal d 7. The perinatally exposed females were aged to 16-17 months and monitored for reproductive senescence. After euthanasia, hypothalamic regions [preoptic area (POA) and medial basal hypothalamus] were dissected for real-time PCR of gene expression or pyrosequencing to assess DNA methylation of the Esr1 gene. Using a 48-gene PCR platform, two genes (Kiss1 and Esr1) were significantly different in the POA of endocrine-disrupting chemical-exposed rats compared with vehicle-exposed rats after Bonferroni correction. Fifteen POA genes were up-regulated by at least 50% in EB or high-dose MXC compared with vehicle. To understand the epigenetic basis of the increased Esr1 gene expression, we performed bisulfite conversion and pyrosequencing of the Esr1 promoter. EB-treated rats had significantly higher percentage of methylation at three CpG sites in the Esr1 promoter compared with control rats. Together with these molecular effects, perinatal MXC and EB altered estrous cyclicity and advanced reproductive senescence. Thus, early life exposure to endocrine disruptors has lifelong effects on neuroendocrine gene expression and DNA methylation, together with causing the advancement of reproductive senescence.

Topics: Animals; Animals, Newborn; Base Sequence; Body Weight; CpG Islands; DNA Methylation; Endocrine Disruptors; Estradiol; Estrogen Receptor alpha; Estrous Cycle; Female; Gene Expression Profiling; Gene Expression Regulation; Kisspeptins; Maternal-Fetal Exchange; Menopause, Premature; Methoxychlor; Molecular Sequence Data; Pregnancy; Preoptic Area; Progesterone; Promoter Regions, Genetic; Rats; Rats, Inbred F344; Regulatory Sequences, Nucleic Acid; Up-Regulation

Topics: Body Mass Index; Body Weight; Female; Humans; Kisspeptins; Puberty, Precocious; Tumor Suppressor Proteins

Kisspeptins (Kp) have recently emerged as master regulators of the reproductive axis and among the most potent elicitors of GnRH-gonadotropin secretion. Despite their paramount importance in reproductive physiology and their potential therapeutic implications, development of Kp antagonists has remained elusive, and only recently has the first compound with the ability to block Kp actions in vitro and in vivo, namely p234, been reported. However, previous in vivo studies all used acute central injections, whereas characterization of the effects of the antagonist after continuous or systemic administration, which poses pharmacological challenges, is still pending. We report herein a comprehensive series of analyses on the impact of continuous intracerebroventricular infusion of p234 on puberty onset and the preovulatory surge of gonadotropins in the female rat. In addition, the effects of systemic (ip) administration of a tagged p234-penetratin, with a predicted higher permeability at the blood-brain barrier, on Kp-10 induced gonadotropin secretion were evaluated. Central infusion of p234 to pubertal females delayed vaginal opening and decreased uterine and ovarian weights at the expected time of puberty, without affecting body weight. Likewise, chronic intracerebroventricular administration of p234 for 4 d prevented the preovulatory surges of LH and FSH. In addition, systemic (ip) administration of p234-penetratin significantly attenuated acute LH and FSH responses to Kp-10, either after intracerebroventricular or ip injection of Kp. Our data document the validity of p234 for antagonizing Kp actions in vivo and provide direct experimental evidence for the important role of Kp signaling in the key events of female reproduction, such as puberty onset and the preovulatory surge of gonadotropins.

Topics: Animals; Body Weight; Estrus; Female; Injections, Intraventricular; Kisspeptins; Male; Oligopeptides; Ovary; Ovulation; Peptides; Rats; Rats, Wistar; Sexual Maturation; Uterus

Using long-term streptozotocin (STZ)-treated male rats, we recently proposed that defective function of hypothalamic KiSS-1 system is mechanistically relevant for central hypogonadotropism of uncontrolled diabetes. However, the temporal pattern of such defects and its potential contribution to disturbed gonadotropin secretion in the diabetic female remain so far unexplored. To cover these issues, expression analyses and hormonal tests were conducted in diabetic male (1 wk after STZ; short term) and female (4 wk after STZ; long term) rats. Short-term diabetic males had lower basal testosterone levels and decreased gonadotropin responses to orchidectomy (ORX), which associated with significantly attenuated post-ORX rises of hypothalamic KiSS-1 mRNA. Yet kisspeptin administration to diabetic males was able to acutely elicit supramaximal LH and testosterone responses and normalize post-ORX gonadotropin secretion. Long-term diabetic females showed persistent anestrus and significantly decreased basal gonadotropin levels as well as blunted LH responses to ovariectomy; changes that were linked to lowering of basal and postovariectomy expression of hypothalamic KiSS-1 mRNA. Moreover, despite prevailing gonadotropin suppression, LH responses to acute kisspeptin administration were fully preserved, and even enhanced after its repeated injection, in diabetic females. In sum, our present findings further define the temporal course and mechanistic relevance of altered hypothalamic KiSS-1 system in the hypogonadotropic state of uncontrolled diabetes. Furthermore, our data provide the basis for the potential therapeutic intervention of the KiSS-1 system as adjuvant in the management of disturbed gonadotropin secretion of type 1 diabetes in the female.

Topics: Animals; Blood Glucose; Body Weight; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Female; Hypothalamus; Kisspeptins; Luteinizing Hormone; Male; Orchiectomy; Ovariectomy; Proteins; Rats; Rats, Wistar; Signal Transduction; Streptozocin; Testosterone; Time Factors

Changes in metabolic state, such as those induced by fasting, have profound effects on reproduction. In rats, the time-course over which fasting inhibits luteinising hormone (LH) release is reduced to 48 h by the presence of oestradiol-17beta (E(2)). Hypothalamic kisspeptin plays a key role in mediating the actions of E(2) on gonadotrophin-releasing hormone (GnRH) neurones, and thereby promotes LH release. KiSS-1-expressing neurones are found in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (ARC). Extensive evidence implicates the AVPV in GnRH release and the ARC in energy balance. The latter nucleus also contains neurones that express neuropeptide Y (NPY), an orexigenic peptide implicated in GnRH control. To elucidate the involvement of kisspeptin and/or NPY in hypothalamic responses to fasting, their expression was quantified by in situ hybridisation histochemistry in ovariectomised rats, with or without E(2) replacement, before and after 48 h of fasting. In the presence of E(2), but not in its absence, the fasting suppressed plasma LH. In the AVPV, the low level of KiSS-1 expression found in the absence of E(2) was unaffected by fasting. By contrast, the elevated level found in the presence of E(2) was suppressed by fasting. Independent of E(2), fasting had no effect on KiSS-1 expression in the ARC, but increased NPY expression at that site. The present study has identified the AVPV as a site at which KiSS-1 expression can be influenced by fasting. The results suggest that inhibition of KiSS-1 expression in the AVPV may be a significant factor in restraining the gonadotrophic axis in response to negative energy balance in the presence of oestrogen. The extent to which the concurrent rise in NPY expression in the ARC may contribute to the suppression of LH release by influencing AVPV kisspeptin neurones, directly or indirectly, or by actions independent of kisspeptin, remains to be established.

Topics: Animals; Anterior Thalamic Nuclei; Arcuate Nucleus of Hypothalamus; Body Weight; Down-Regulation; Fasting; Female; Kisspeptins; Luteinizing Hormone; Neurons, Afferent; Neuropeptide Y; Proteins; Rats; Rats, Wistar; RNA, Messenger

In order to reproduce successfully, animals must integrate multiple environmental cues to synchronize breeding with favorable conditions. In temperate, seasonally breeding rodents, photoperiod acts as the primary seasonal cue. Long days are associated with reproductive development and maturation of the gonads whereas short days induce gonadal regression. The neuropeptide kisspeptin has potent stimulatory effects on reproductive development. Kisspeptin potently stimulates GnRH release and kisspeptin expression co-varies with photoperiod in seasonally breeding animals. Here we tested the hypothesis that reproductive involution in response to inhibitory day lengths results from reduced kisspeptin stimulation of the reproductive axis in seasonally breeding Siberian hamsters (Phodopus sungorus). If true, gonadal regrowth should be hastened by kisspeptin treatment in regressed hamsters and prevented in hamsters by treatment prior to and during regression. In Experiments 1 and 2 we tested the ability of kisspeptin to reverse gonadal regression. In Experiment 1, reproductively regressed hamsters received chronic kisspeptin via osmotic mini-pumps for 4 weeks. In Experiment 2, daily injections of kisspeptin were administered to regressed hamsters for 6 weeks. In Experiment 3, the ability of kisspeptin to block gonadal regression was tested; hamsters transferred to short days received daily injections of kisspeptin for 6 weeks. In all three studies, short-day animals receiving exogenous kisspeptin did not differ from short-day controls. Collectively, these results provide evidence that mechanisms in addition to those that converge on the kisspeptin system are likely critical for seasonal changes in the reproductive axis.

Topics: Animals; Body Weight; Cricetinae; Follicle Stimulating Hormone; Kisspeptins; Luteinizing Hormone; Male; Oligopeptides; Phodopus; Photoperiod; Reproduction; Sexual Behavior, Animal; Testis; Testosterone

Kisspeptins have emerged as potent elicitors of gonadotropin secretion and, therefore, putative targets for pharmacological intervention. In this context, desensitization of gonadotropin responses to continuous administration of kisspeptins has begun to be characterized, but information so far available is mostly restricted to LH responses in males, whereas the similar phenomenon in females, of obvious therapeutic interest, remains virtually unexplored. We report herein LH and FSH responses to continuous intracerebral administration of kisspeptin in female rats at different developmental and metabolic states. Infusion of kisspeptin-10 to adult female rats induced a transient elevation in serum LH concentrations, followed by a precipitous drop and normalization of LH levels thereafter. Elevation of LH after kisspeptin infusion was prolonged in underfed animals; a phenomenon mimicked by leptin administration. Conversely, FSH levels were persistently heightened along continuous kisspeptin infusion, but duration of this response was shortened by undernutrition. In pubertal females, LH and FSH levels remained elevated at the end of a 7-day infusion of kisspeptin; responses whose magnitude was augmented by subnutrition but not mimicked by leptin. In all settings, terminal gonadotropin-releasing hormone responses were fully preserved, suggesting that eventual desensitization must occur upstream from the pituitary. In summary, our current data document the pharmacological consequences of continuous administration of kisspeptin to female rats, with remarkable differences being detected between LH and FSH responses, in different developmental and metabolic states. These observations of potential pharmacological interest might help also to delineate the physiological roles of kisspeptins in the dynamic regulation of gonadotropin secretion in the female.

Topics: Age Factors; Animals; Body Weight; Eating; Female; Follicle Stimulating Hormone; Kisspeptins; Leptin; Luteinizing Hormone; Oligopeptides; Rats; Rats, Wistar; Sexual Maturation

Estradiol and progesterone induction of the LH surge in ovariectomized female rats requires concurrent activation of brain insulin-like growth factor 1 (IGF1) receptors. The present study determined whether brain IGF1 receptor signaling is required for estrous cyclicity in gonadally intact female rats. A selective IGF1 receptor antagonist (JB-1) or vehicle was continuously administered into the third ventricle by osmotic minipumps. Following surgical placement of the minipumps, all rats temporarily reduced food intake, lost weight, and suspended estrous cycles. Control rats resumed cycles within a few days and exhibited compensatory hyperphagia until they returned to presurgical body weight. Animals receiving JB-1 had severely delayed or absent estrous cycles, failed to show rebound feeding, and regained body weight more slowly. Vehicle-infused animals pair fed to JB-1-treated rats had even lower body weights but resumed estrous cycles sooner than those given drug alone. Chronic infusion of IGF1 alone had no effect on any of these parameters, but coinfusion of IGF1 with the antagonist completely reversed JB-1 effects on food intake and estrous cyclicity and partially reversed the effects on body weight. There were no significant differences in the expression of galanin-like peptide (Galp) or Kiss1 mRNA in the arcuate or periventricular hypothalamic area of control and JB-1-treated animals at a time point when food intake and estrous cycles were different between controls and JB-1-treated rats. These data suggest that brain IGF1 signaling is necessary for normal estrous cycles as well as compensatory hyperphagia and that IGF1 modulation of the reproductive axis is not secondary to reduced food intake.

Topics: Animals; Blood Glucose; Body Weight; Brain; Eating; Estrous Cycle; Female; Galanin-Like Peptide; Hyperphagia; In Situ Hybridization; Insulin; Kisspeptins; Leptin; Proteins; Rats; Rats, Sprague-Dawley; Receptor, IGF Type 1; RNA, Messenger; Signal Transduction

The effect of continuous administration of the C-terminal fragment of metastin, the ligand for the G protein-coupled receptor, GPR54, on GnRH-induced LH secretion was examined in three agonadal, juvenile male monkeys whose responsiveness to GnRH was heightened by pretreatment with a chronic pulsatile iv infusion of synthetic GnRH. After bolus injection of 10 microg human (hu) metastin 45-54 (equivalent to kisspeptin 112-121), the GPR54 agonist was infused continuously at a dose of 100 microg/h and elicited a brisk LH response for approximately 3 h. This rise was then followed by a precipitous drop in LH despite continuous exposure of GPR54 to metastin 45-54. On d 4, during the final 3 h of the infusion, single boluses of hu metastin 45-54 (10 microg), N-methyl-DL-aspartic acid (NMDA) (10 mg/kg) and GnRH (0.3 microg) were administered to interrogate each element of the metastin-GPR54-GnRH-GnRH receptor cascade. Although the NMDA and GnRH boluses were able to elicit LH pulses, that of hu metastin 45-54 was not, demonstrating functional integrity of GnRH neurons (NMDA) and GnRH receptors (NMDA and GnRH) but desensitization of GPR54. The desensitization of GPR54 by continuous hu metastin 45-54 administration has therapeutic implications for a variety of conditions currently being treated by GnRH and its analogs, including restoration of fertility in patients with abnormal GnRH secretion (i.e. idiopathic hypogonadotropic hypogonadism and hypothalamic amenorrhea) and selective, reversible suppression of the pituitary-gonadal axis to achieve suppression of gonadal steroids (i.e. precocious puberty, endometriosis, uterine fibroids, and prostate cancer).

Topics: Animals; Biological Assay; Body Weight; Humans; Infusions, Intravenous; Kisspeptins; Ligands; Luteinizing Hormone; Macaca mulatta; Male; Models, Biological; N-Methylaspartate; Pituitary Gland; Prostatic Neoplasms; Proteins; Receptors, G-Protein-Coupled; Receptors, Galanin; Receptors, Kisspeptin-1; Receptors, LHRH; Time Factors; Tumor Suppressor Proteins

Kisspeptins are products of the Kiss1 gene, which bind to GPR54, a G protein-coupled receptor. Kisspeptins and GPR54 have been implicated in the neuroendocrine regulation of GnRH secretion. To test the hypothesis that testosterone regulates Kiss1 gene expression, we compared the expression of KiSS-1 mRNA among groups of intact, castrated, and castrated/testosterone (T)-treated male mice. In the arcuate nucleus (Arc), castration resulted in a significant increase in KiSS-1 mRNA, which was completely reversed with T replacement, whereas in the anteroventral periventricular nucleus, the results were the opposite, i.e. castration decreased and T increased KiSS-1 mRNA expression. In the Arc, the effects of T on KiSS-1 mRNA were completely mimicked by estrogen but only partially mimicked by dihydrotestosterone, a nonaromatizable androgen, suggesting that both estrogen receptor (ER) and androgen receptor (AR) play a role in T-mediated regulation of KiSS-1. Studies of the effects of T on KiSS-1 expression in mice with either a deletion of the ERalpha or a hypomorphic allele to the AR revealed that the effects of T are mediated by both ERalpha and AR pathways, which was confirmed by the presence of either ERalpha or AR coexpression in most KiSS-1 neurons in the Arc. These observations suggest that KiSS-1 neurons in the Arc, whose transcriptional activity is inhibited by T, are targets for the negative feedback regulation of GnRH secretion, whereas KiSS-1 neurons in the anteroventral periventricular nucleus, whose activity is stimulated by T, may mediate other T-dependent processes.

Topics: Animals; Body Weight; Brain; Dihydrotestosterone; Estradiol; Estrogen Receptor alpha; Hormones; In Situ Hybridization; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Orchiectomy; Prosencephalon; Proteins; Receptors, Androgen; RNA, Messenger; Testosterone; Tissue Distribution

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.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Estrogen Receptor alpha; Estrogen Receptor beta; Estrogens; Female; Kisspeptins; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Ovariectomy; Paraventricular Hypothalamic Nucleus; Proteins; RNA, Messenger