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Villa PA, Ruggiero-Ruff RE, Jamieson BB, Campbell RE, Coss D. Obesity Alters POMC and Kisspeptin Neuron Cross Talk Leading to Reduced Luteinizing Hormone in Male Mice. J Neurosci 2024; 44:e0222242024. [PMID: 38744532 PMCID: PMC11236585 DOI: 10.1523/jneurosci.0222-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/19/2024] [Accepted: 05/07/2024] [Indexed: 05/16/2024] Open
Abstract
Obesity is associated with hypogonadism in males, characterized by low testosterone and sperm number. Previous studies determined that these stem from dysregulation of hypothalamic circuitry that regulates reproduction, by unknown mechanisms. Herein, we used mice fed chronic high-fat diet, which mimics human obesity, to determine mechanisms of impairment at the level of the hypothalamus, in particular gonadotropin-releasing hormone (GnRH) neurons that regulate luteinizing hormone (LH), which then regulates testosterone. Consistent with obese humans, we demonstrated lower LH, and lower pulse frequency of LH secretion, but unchanged pituitary responsiveness to GnRH. LH pulse frequency is regulated by pulsatile GnRH secretion, which is controlled by kisspeptin. Peripheral and central kisspeptin injections, and DREADD-mediated activation of kisspeptin neurons, demonstrated that kisspeptin neurons were suppressed in obese mice. Thus, we investigated regulators of kisspeptin secretion. We determined that the LH response to NMDA was lower in obese mice, corresponding to fewer glutamate receptors in kisspeptin neurons, which may be critical for kisspeptin synchronization. Given that kisspeptin neurons also interact with anorexigenic POMC neurons, which are affected by obesity, we examined their cross talk, and determined that the LH response to either DREADD-mediated activation of POMC neurons or central injection of αMSH, a product of POMC, is abolished in obese mice. This was accompanied by diminished levels of αMSH receptor, MC4R, in kisspeptin neurons. Together, our studies determined that obesity leads to the downregulation of receptors that regulate kisspeptin neurons, which is associated with lower LH pulse frequency, leading to lower LH and hypogonadism.
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Affiliation(s)
- Pedro A Villa
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California 92521
| | - Rebecca E Ruggiero-Ruff
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California 92521
| | - Bradley B Jamieson
- Centre for Neuroendocrinology, and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology, and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Djurdjica Coss
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California 92521
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Nestor CC, Merkley CM, Lehman MN, Hileman SM, Goodman RL. KNDy neurons as the GnRH pulse generator: Recent studies in ruminants. Peptides 2023; 164:171005. [PMID: 36990389 PMCID: PMC10164117 DOI: 10.1016/j.peptides.2023.171005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/10/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023]
Abstract
This review considers three aspects of recent work on the role of KNDy neurons in GnRH pulse generation in ruminants. First, work on basic mechanisms of pulse generation includes several tests of this hypothesis, all of which support it, and evidence that Kiss1r-containing neurons form a positive feedback circuit with the KNDy neural network that strengthen the activity of this network. The second section on pathways mediating external inputs focuses on the influence of nutrition and photoperiod, and describes the evidence supporting roles for proopiomelanocortin (POMC) and agouti-related peptide (AgRP) afferents to KNDy cells in each of these. Finally, we review studies exploring the potential applications of manipulating signaling by kisspeptin, and the other KNDy peptides, to control reproductive function in domestic animals and conclude that, although these approaches show some promise, they do not have major advantages over current practices at this time.
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Affiliation(s)
- Casey C Nestor
- Department of Animal Science, North Carolina State University, Raleigh, NC, USA
| | | | - Michael N Lehman
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Stanley M Hileman
- Department of Physiology, Pharmacology, and Toxicology, West Virginia University, Morgantown, WV, USA
| | - Robert L Goodman
- Department of Physiology, Pharmacology, and Toxicology, West Virginia University, Morgantown, WV, USA.
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Ma Y, Awe O, Radovick S, Yang X, Divall S, Wolfe A, Wu S. Lower FSH With Normal Fertility in Male Mice Lacking Gonadotroph Kisspeptin Receptor. Front Physiol 2022; 13:868593. [PMID: 35557961 PMCID: PMC9089166 DOI: 10.3389/fphys.2022.868593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/31/2022] [Indexed: 12/03/2022] Open
Abstract
The kisspeptin receptor, crucial for hypothalamic control of puberty and reproduction, is also present in the pituitary gland. Its role in the pituitary gland is not defined. Kisspeptin signaling via the Kiss1r could potentially regulate reproductive function at the level of pituitary gonadotrope. Using Cre/Lox technology, we deleted the Kiss1r gene in pituitary gonadotropes (PKiRKO). PKiRKO males have normal genital development (anogenital distance WT: 19.1 ± 0.4 vs. PKiRKO: 18.5 ± 0.4 mm), puberty onset, testes cell structure on gross histology, normal testes size, and fertility. PKiRKO males showed significantly decreased serum FSH levels compared to WT males (5.6 ± 1.9 vs. 10.2 ± 1.8 ng/ml) with comparable LH (1.1 ± 0.2 vs. 1.8 ± 0.4 ng/ml) and testosterone levels (351.8 ± 213.0 vs. 342.2 ± 183.0 ng/dl). PKiRKO females have normal puberty onset, cyclicity, LH and FSH levels and fertility. Overall, these findings indicate that absence of pituitary Kiss1r reduces FSH levels in male mice without affecting testis function. PKiRKO mice have normal reproductive function in both males and females.
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Affiliation(s)
- Yaping Ma
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Pediatrics, Affiliated Hospital of Jiangnan University, Wuxi, China
| | - Olubusayo Awe
- Department of Cellular and Molecular Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sally Radovick
- Department of Pediatrics, Rutgers University Medical School, New Brunswick, NJ, United States
| | - Xiaofeng Yang
- Department of Cardiovascular Sciences, Center for Metabolic Disease Research, Temple University School of Medicine, Philadelphia, PA, United States
| | - Sara Divall
- Department of Pediatrics, University of Washington, Seattle's Children's Hospital, Seattle, United States
| | - Andrew Wolfe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Sheng Wu
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Cellular and Molecular Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Cardiovascular Sciences, Center for Metabolic Disease Research, Temple University School of Medicine, Philadelphia, PA, United States
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4
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Kavanagh GS, Tadi J, Balkenhol SM, Kauffman AS, Maloney SK, Smith JT. Kisspeptin impacts on circadian and ultradian rhythms of core body temperature: Evidence in kisspeptin receptor knockout and kisspeptin knockdown mice. Mol Cell Endocrinol 2022; 542:111530. [PMID: 34896241 PMCID: PMC9907773 DOI: 10.1016/j.mce.2021.111530] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 01/26/2023]
Abstract
Kisspeptin is vital for the regulation of both fertility and metabolism. Kisspeptin receptor (Kiss1r) knockout (KO) mice exhibit increased adiposity and reduced energy expenditure in adulthood. Kiss1r mRNA is expressed in brown adipose tissue (BAT) and Kiss1r KO mice exhibit reduced Ucp1 mRNA in BAT and impaired thermogenesis. We hypothesised that mice with diminished kisspeptin signalling would exhibit reduced core body temperature (Tc) and altered dynamics of circadian and ultradian rhythms of Tc. Tc was recorded every 15-min over 14-days in gonadectomised wild-type (WT), Kiss1r KO, and also Kiss1-Cre (95% reduction in Kiss1 transcription) mice. Female Kiss1r KOs had higher adiposity and lower Ucp1 mRNA in BAT than WTs. No change was detected in Kiss1-Cre mice. Mean Tc during the dark phase was lower in female Kiss1r KOs versus WTs, but not Kiss1-Cre mice. Female Kiss1r KOs had a lower mesor and amplitude of the circadian rhythm of Tc than did WTs. In WT mice, there were more episodic ultradian events (EUEs) of Tc during the dark phase than the light phase, but this measure was similar between dark and light phases in Kiss1r KO and Kiss1-Cre mice. The amplitude of EUEs was higher in the dark phase in female Kiss1r KO and male Kiss1-Cre mice. Given the lack of clear metabolic phenotype in Kiss1-Cre mice, 5% of Kiss1 transcription may be sufficient for proper metabolic control, as was shown for fertility. Moreover, the observed alterations in Tc suggest that kisspeptin has a role in circadian and ultradian rhythm-driven pathways.
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Affiliation(s)
- Georgia S Kavanagh
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Jason Tadi
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Sydney M Balkenhol
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Alexander S Kauffman
- Department of OBGYN and Reproductive Sciences, University of California, San Diego, La Jolla, CA, USA
| | - Shane K Maloney
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Jeremy T Smith
- School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia.
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Effect of Electroacupuncture on Reproductive Disorders and Insulin Resistance in a Murine Polycystic Ovary Syndrome Model. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2021; 2021:9968463. [PMID: 34987599 PMCID: PMC8720607 DOI: 10.1155/2021/9968463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 09/02/2021] [Accepted: 09/15/2021] [Indexed: 12/19/2022]
Abstract
Polycystic ovarian syndrome (PCOS) is a common, complex, and heterogeneous endocrine and metabolic disorder. There is no standardized treatment, and it therefore requires individualized therapies according to the symptoms and pathogenesis of each patient. The present study aimed to determine the effect of electroacupuncture at the acupoints Zusanli (ST36), Sanyinjiao (SP6), and Neiguan (PC6) on reproductive disorders and insulin resistance in a murine model of PCOS induced by dehydroepiandrosterone (DHEA). Vaginal smear analysis was used to determine mice estrous cycle; intraperitoneal glucose and insulin tolerance tests were adopted to analyze metabolic characteristics; enzyme-linked immunosorbent assay was used to measure hormone levels; gene expression was quantified with real-time PCR; hematoxylin and eosin staining was used to observe ovarian morphology. We observed disordered estrous cycle, polycystic ovarian morphology, and higher levels of homeostasis model assessment-insulin resistance (HOMA-IR) and testosterone (T), indicating successful modeling of PCOS. DHEA increased levels of estrogen (E2), progesterone (P), testosterone (T), luteinizing hormone (LH), and follicle-stimulating hormone (FSH), and EA treatment restored them to levels seen in the control group. EA reduced the days in estrus caused by DHEA, improved the abnormal sex hormone receptor genes, and attenuated the DHEA-induced histomorphological changes in mouse ovaries. The average expressions of the androgen receptor (AR), estrogen receptor (ER), luteinizing hormone receptor (LHR), and follicle-stimulating hormone receptor (FSHR) genes in the ovary greatly increased after DHEA treatment and significantly decreased in the DHEA + EA group. After EA treatment, the cystic follicle (CF) number was reduced and corpora lutea (CL) increased in the DHEA + EA group compared to the DHEA group. EA improved glucose intolerance and insulin intolerance. Statistical analysis of intraperitoneal glucose tolerance test-area under curve (IPGTT-AUC) glucose levels revealed a significant decrease in DHEA group mice compared to the control and DHEA + EA groups. EA was found to restore fasting blood glucose, fasting serum insulin, and HOMA-IR. In summary, our study suggests that EA has a remarkable effect in the DHEA-induced murine PCOS model. Management of EA could improve estrous cycle, hormonal disorders, abnormal sex hormone receptors in ovaries, ovary morphology, and insulin resistance in PCOS mice.
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Kumbar J, Ganesh CB. The effect of α-MSH treatment on the hypothalamic-pituitary-gonad axis in the cichlid fish Oreochromis mossambicus. FISH PHYSIOLOGY AND BIOCHEMISTRY 2021; 47:1659-1668. [PMID: 34460040 DOI: 10.1007/s10695-021-01005-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/14/2021] [Indexed: 06/13/2023]
Abstract
In this investigation, we examined the influence of alpha-melanocyte stimulating hormone (α-MSH), a proopiomelanocortin-derived peptide, along the hypothalamic-pituitary-gonad axis in a cichlid fish Oreochromis mossambicus. Administration of α-MSH (40 µg/0.1 ml saline) for 22 days did not affect the number of stage I (previtellogenic) follicles but caused significant reduction in the mean numbers of previtellogenic (stages II and III), vitellogenic (stage IV) and preovulatory (stage V) follicles compared to those of controls. While the gonadosomatic index was significantly lower, the rate of follicular atresia in stages II, III and IV remained significantly higher in α-MSH-treated fish compared to the controls. Furthermore, the mean percent area of gonadotropin-releasing hormone-immunoreactive (GnRH-ir) fibres and luteinizing hormone-immunoreactive (LH-ir) cells were significantly reduced in the proximal pars distalis of the pituitary gland in α-MSH-treated fish compared with the controls. Together, our findings suggest for the first time that the treatment of α-MSH blocks the follicular developmental process during the ovarian cycle, possibly through the inhibition of GnRH-LH pathway in teleosts.
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Affiliation(s)
- Jyoti Kumbar
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad, 580 003, India
| | - C B Ganesh
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad, 580 003, India.
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Murillo-Rodríguez E, Millán-Aldaco D, Arankowsky-Sandoval G, Yamamoto T, Pertwee RG, Parker L, Mechoulam R. Assessing the treatment of cannabidiolic acid methyl ester: a stable synthetic analogue of cannabidiolic acid on c-Fos and NeuN expression in the hypothalamus of rats. J Cannabis Res 2021; 3:31. [PMID: 34253253 PMCID: PMC8276432 DOI: 10.1186/s42238-021-00081-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 06/14/2021] [Indexed: 04/03/2024] Open
Abstract
BACKGROUND Cannabidiol (CBD), the non-psychotropic compound from Cannabis sativa, shows positive results on controlling several health disturbances; however, comparable data regarding additional chemical from C. sativa, such as cannabidiolic acid (CBDA), is scarce due to its instability. To address this limitation, a stable CBDA analogue, CBDA methyl ester (HU-580), was synthetized and showed CBDA-like effects. Recently, we described that HU-580 increased wakefulness and wake-related neurochemicals. OBJECTIVE To extend the comprehension of HU-580´s properties on waking, the c-Fos and NeuN expression in a wake-linked brain area, the hypothalamus was evaluated. METHODS c-Fos and NeuN expression in hypothalamic sections were analyzed after the injections of HU-580 (0.1 or 100 μg/kg, i.p.). RESULTS Systemic administrations of HU-580 increased c-Fos and neuronal nuclei (NeuN) expression in hypothalamic nuclei, including the dorsomedial hypothalamic nucleus dorsal part, dorsomedial hypothalamic nucleus compact part, and dorsomedial hypothalamic nucleus ventral part. CONCLUSION HU-580 increased c-Fos and NeuN immunoreactivity in hypothalamus nuclei suggesting that this drug might modulate the sleep-wake cycle by engaging the hypothalamus.
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Affiliation(s)
- Eric Murillo-Rodríguez
- Laboratorio de Neurociencias Moleculares e Integrativas Escuela de Medicina, División Ciencias de la Salud, Universidad Anáhuac Mayab Mérida, Km. 15.5 Carretera Mérida-Progreso, Int. Km. 2 Carretera a Chablekal, Yucatán, C.P. 97,308, Mérida, México.
- Intercontinental Neuroscience Research Group, Mérida, Yucatán, México.
| | - Diana Millán-Aldaco
- Depto. de Neurociencia Cognitiva. División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Gloria Arankowsky-Sandoval
- Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, Yucatán, México
| | - Tetsuya Yamamoto
- Intercontinental Neuroscience Research Group, Mérida, Yucatán, México
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima, Japan
| | - Roger G Pertwee
- School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Linda Parker
- Department of Psychology and Neuroscience Graduate Program, University of Guelph, Guelph, Ontario, Canada
| | - Raphael Mechoulam
- Institute for Drug Research, Medical Faculty, Hebrew University, Jerusalem, Israel
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Stincic TL, Rønnekleiv OK, Kelly MJ. Membrane and nuclear initiated estrogenic regulation of homeostasis. Steroids 2021; 168:108428. [PMID: 31229508 PMCID: PMC6923613 DOI: 10.1016/j.steroids.2019.108428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 06/08/2019] [Accepted: 06/18/2019] [Indexed: 11/23/2022]
Abstract
Reproduction and energy balance are inextricably linked in order to optimize the evolutionary fitness of an organism. With insufficient or excessive energy stores a female is liable to suffer complications during pregnancy and produce unhealthy or obesity-prone offspring. The quintessential function of the hypothalamus is to act as a bridge between the endocrine and nervous systems, coordinating fertility and autonomic functions. Across the female reproductive cycle various motivations wax and wane, following levels of ovarian hormones. Estrogens, more specifically 17β-estradiol (E2), coordinate a triumvirate of hypothalamic neurons within the arcuate nucleus (ARH) that govern the physiological underpinnings of these behavioral dynamics. Arising from a common progenitor pool of cells, this triumvirate is composed of the kisspeptin (Kiss1ARH), proopiomelanocortin (POMC), and neuropeptide Y/agouti-related peptide (AgRP) neurons. Although the excitability of these neuronal subpopulations is subject to genomic and rapid estrogenic regulation, kisspeptin neurons are the most sensitive, reflecting their integral function in female fertility. Based on the premise that E2 coordinates autonomic functions around reproduction, we will review the recent findings on the synaptic interactions between Kiss1, AgRP and POMC neurons and how the rapid membrane-initiated and intracellular signaling cascades activated by E2 in these neurons are critical for control of homeostatic functions supporting reproduction.
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Affiliation(s)
- Todd L Stincic
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, United States
| | - Oline K Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, United States; Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, United States
| | - Martin J Kelly
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, United States; Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, United States.
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Merkley CM, Shuping SL, Sommer JR, Nestor CC. Evidence That Agouti-Related Peptide May Directly Regulate Kisspeptin Neurons in Male Sheep. Metabolites 2021; 11:138. [PMID: 33652696 PMCID: PMC7996775 DOI: 10.3390/metabo11030138] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 12/21/2022] Open
Abstract
Agouti-related peptide (AgRP) neurons, which relay information from peripheral metabolic signals, may constitute a key central regulator of reproduction. Given that AgRP inhibits luteinizing hormone (LH) secretion and that nutritional suppression of LH elicits an increase in AgRP while suppressing kisspeptin expression in the arcuate nucleus (ARC) of the hypothalamus, we sought to examine the degree to which AgRP could directly regulate ARC kisspeptin neurons. Hypothalamic tissue was collected from four castrated male sheep (10 months of age) and processed for the detection of protein (AgRP input to kisspeptin neurons) using immunohistochemistry and mRNA for melanocortin 3 and 4 receptors (MC3R; MC4R) in kisspeptin neurons using RNAscope. Immunohistochemical analysis revealed that the majority of ARC kisspeptin neurons are contacted by presumptive AgRP terminals. RNAscope analysis revealed that nearly two thirds of the ARC kisspeptin neurons express mRNA for MC3R, while a small percentage (<10%) colocalize MC4R. Taken together, this data provides neuroanatomical evidence for a direct link between orexigenic AgRP neurons and reproductively critical kisspeptin neurons in the sheep, and builds upon our current understanding of the central link between energy balance and reproduction.
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Affiliation(s)
| | | | | | - Casey C Nestor
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA; (C.M.M.); (S.L.S.); (J.R.S.)
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Patel R, Smith JT. Novel actions of kisspeptin signaling outside of GnRH-mediated fertility: a potential role in energy balance. Domest Anim Endocrinol 2020; 73:106467. [PMID: 32278499 DOI: 10.1016/j.domaniend.2020.106467] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 01/08/2023]
Abstract
Kisspeptin, encoded by Kiss1 gene expressing neurons in the hypothalamus, is a requisite for fertility and now appears critical in the regulation of energy balance. Kisspeptin neurons, particularly those in the arcuate nucleus (ARC), receive information directly and indirectly from a diverse array of brain regions including the bed nucleus of the stria terminalis, amygdala, interpeduncular nucleus, hippocampus, and cortex. On the other hand, kisspeptin neuron projections clearly extend to GnRH neuron cell bodies in rodents, sheep, and primates and beyond to other-non-GnRH-brain areas. Kiss1r, the kisspeptin receptor, is expressed on GnRH neurons and also in additional brain areas and peripheral tissues, indicating a nonreproductive role. Kisspeptin neurons clearly receive signals pertinent to deviations in energy balance but are now recognized as a novel neuroendocrine player in the fine balance of energy intake and expenditure. Mice that have a dysfunctional gene for Kiss1r develop an obese and diabetic phenotype. The mechanism behind this altered metabolic state is still mostly unknown; however, Kiss1r expression in the pancreas and brown adipose tissue is clearly functional and required for normal glucose tolerance and energy expenditure, respectively. Kisspeptin neurons in the ARC also participate in the generation of circadian rhythms, specifically those concerning food intake and metabolism, offering a potential explanation for the obesity in Kiss1r knockout mice. Overall, the discoveries of new mechanistic roles for kisspeptin in both normal and pathophysiologic states of energy balance may lead to further understating of obesity prevalence and novel therapeutic targets and interventions.
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Affiliation(s)
- R Patel
- School of Human Sciences, M309, The University of Western Australia, 35 Stirling Highway Crawley, Perth, Western Australia, Australia 6009
| | - J T Smith
- School of Human Sciences, M309, The University of Western Australia, 35 Stirling Highway Crawley, Perth, Western Australia, Australia 6009.
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Lents CA, Lindo AN, Hileman SM, Nonneman DJ. Physiological and genomic insight into neuroendocrine regulation of puberty in gilts. Domest Anim Endocrinol 2020; 73:106446. [PMID: 32199704 DOI: 10.1016/j.domaniend.2020.106446] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 12/20/2022]
Abstract
The timing of pubertal attainment in gilts is a critical factor for pork production and is an early indicator of future reproductive potential. Puberty, defined as age at first standing estrus in the presence of a boar, is brought about by an escape from estrogen inhibition of the GnRH pulse generator, which allows for increasing LH pulses leading to the onset of cyclicity. The biological mechanisms that control the timing of these events is related to decreasing inhibitory signals with a concomitant increase in stimulatory signals within the hypothalamus. The roles of gamma-aminobutyric acid, endogenous opioid peptides, and gonadotropin-inhibitory hormone in negatively regulating gonadotropin secretion in gilts is explored. Developmental changes in stimulatory mechanisms of glutamatergic and kisspeptin neurons are important for increased LH pulsatility required for the occurrence of puberty in pigs. Age at first estrus of gilts is metabolically gated, and numerous metabolites, metabolic hormones, and appetite-regulating neurotransmitters have been implicated in the nutritional regulation of gonadotropin secretion. Leptin is an important metabolic signal linking body energy reserves with age at puberty in gilts. Leptin acting through neuropeptide Y and proopiomelanocortin neurons in the hypothalamus has important impacts on the function of the reproductive neurosecretory axis of gilts. Age at puberty in swine is heritable, and genomic analyses reveal it to be a polygenic trait. Genome-wide association studies for pubertal age in gilts have revealed several genomic regions in common with those identified for age at menarche in humans. Candidate genes have been identified that have important functions in growth and adiposity. Numerous genes regulating hypothalamic neuronal function, gonadotropes in the adenohypophysis, and ovarian follicular development have been identified and illustrate the complex maturational changes occurring in the hypothalamic-pituitary-ovarian axis during puberty in gilts.
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Affiliation(s)
- C A Lents
- USDA, ARS, U.S. Meat Animal Research Center, Reproduction Research Unit, Clay Center, NE 68966-0166, USA.
| | - A N Lindo
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506-9600, USA
| | - S M Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506-9600, USA
| | - D J Nonneman
- USDA, ARS, U.S. Meat Animal Research Center, Reproduction Research Unit, Clay Center, NE 68966-0166, USA
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Cardoso RC, West SM, Maia TS, Alves BRC, Williams GL. Nutritional control of puberty in the bovine female: prenatal and early postnatal regulation of the neuroendocrine system. Domest Anim Endocrinol 2020; 73:106434. [PMID: 32115309 DOI: 10.1016/j.domaniend.2020.106434] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 01/25/2023]
Abstract
Puberty is a complex biological event that requires maturation of the reproductive neuroendocrine axis and subsequent initiation of high-frequency, episodic release of GnRH and LH. Nutrition is a critical factor affecting the neuroendocrine control of puberty. Although nutrient restriction during juvenile development delays puberty, elevated rates of body weight gain during this period facilitate pubertal maturation by programming hypothalamic centers that underlie the pubertal process. Recent findings suggest that maternal nutrition during gestation can also modulate the development of the fetal neuroendocrine axis, thus influencing puberty and subsequent reproductive function. Among the several metabolic signals, leptin plays a critical role in conveying metabolic information to the brain and, consequently, controlling puberty. The effects of leptin on GnRH secretion are mediated via an upstream neuronal network because GnRH neurons do not express the leptin receptor. Two neuronal populations located in the arcuate nucleus that express the orexigenic peptide neuropeptide Y (NPY), and the anorexigenic peptide alpha melanocyte-stimulating hormone (αMSH), are key components of the neurocircuitry that conveys inhibitory (NPY) and excitatory (αMSH) inputs to GnRH neurons. In addition, neurons in the arcuate nucleus that coexpress kisspeptin, neurokinin B, and dynorphin (termed KNDy neurons) are also involved in the metabolic control of puberty. Our studies in the bovine female demonstrate that increased planes of nutrition during juvenile development lead to organizational and functional changes in hypothalamic pathways comprising NPY, proopiomelanocortin (POMC, the precursor of αMSH), and kisspeptin neurons. Changes include alterations in the abundance of NPY, POMC, and Kiss1 mRNA and in plasticity of the neuronal projections to GnRH neurons. Our studies also indicate that epigenetic mechanisms, such as modifications in the DNA methylation pattern, are involved in this process. Finally, our most recent data demonstrate that maternal nutrition during gestation can also induce morphological and functional changes in the hypothalamic NPY system in the heifer offspring that are likely to persist long after birth. These organizational changes occurring during fetal development have the potential to not only impact puberty but also influence reproductive performance throughout adulthood in the bovine female.
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Affiliation(s)
- R C Cardoso
- Department of Animal Science, Texas A&M University, College Station, TX, USA.
| | - S M West
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - T S Maia
- Department of Animal Science, Texas A&M University, College Station, TX, USA; Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, TX, USA
| | - B R C Alves
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - G L Williams
- Department of Animal Science, Texas A&M University, College Station, TX, USA; Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, TX, USA
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13
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Parker CG, Cheung E. Metabolic control of teleost reproduction by leptin and its complements: Understanding current insights from mammals. Gen Comp Endocrinol 2020; 292:113467. [PMID: 32201232 DOI: 10.1016/j.ygcen.2020.113467] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/05/2020] [Accepted: 03/18/2020] [Indexed: 12/15/2022]
Abstract
Reproduction is expensive. Hence, reproductive physiology is sensitive to an array of endogenous signals that provide information on metabolic and nutritional sufficiency. Although metabolic gating of reproductive function in mammals, as evidenced by studies demonstrating delayed puberty and perturbed fertility, has long been understood to be a function of energy sufficiency, an understanding of the endocrine regulators of this relationship have emerged only within recent decades. Peripheral signals including leptin and cortisol have long been implicated in the physiological integration of metabolism and reproduction. Recent studies have begun to explore possible roles for these two hormones in the regulation of reproduction in teleost fishes, as well as a role for leptin as a catabolic stress hormone. In this review, we briefly explore the reproductive actions of leptin and cortisol in mammals and teleost fishes and possible role of both hormones as putative modulators of the reproductive axis during stress events.
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Affiliation(s)
- Coltan G Parker
- Neuroscience Program, Beckman Institute of Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 N Mathews Ave, Urbana, IL, USA
| | - Eugene Cheung
- Department of Biological Sciences, David Clark Labs, 100 Brooks Avenue, North Carolina State University, Raleigh, NC, USA.
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14
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Li SB, de Lecea L. The hypocretin (orexin) system: from a neural circuitry perspective. Neuropharmacology 2020; 167:107993. [PMID: 32135427 DOI: 10.1016/j.neuropharm.2020.107993] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/23/2020] [Accepted: 02/05/2020] [Indexed: 12/11/2022]
Abstract
Hypocretin/orexin neurons are distributed restrictively in the hypothalamus, a brain region known to orchestrate diverse functions including sleep, reward processing, food intake, thermogenesis, and mood. Since the hypocretins/orexins were discovered more than two decades ago, extensive studies have accumulated concrete evidence showing the pivotal role of hypocretin/orexin in diverse neural modulation. New method of viral-mediated tracing system offers the possibility to map the monosynaptic inputs and detailed anatomical connectivity of Hcrt neurons. With the development of powerful research techniques including optogenetics, fiber-photometry, cell-type/pathway specific manipulation and neuronal activity monitoring, as well as single-cell RNA sequencing, the details of how hypocretinergic system execute functional modulation of various behaviors are coming to light. In this review, we focus on the function of neural pathways from hypocretin neurons to target brain regions. Anatomical and functional inputs to hypocretin neurons are also discussed. We further briefly summarize the development of pharmaceutical compounds targeting hypocretin signaling. This article is part of the special issue on Neuropeptides.
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Affiliation(s)
- Shi-Bin Li
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA, 94305, USA.
| | - Luis de Lecea
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA, 94305, USA.
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15
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Farr OM, Mantzoros CS. Old and new tools to study human brain physiology: Current state, future directions and implications for metabolic regulation. Metabolism 2019; 99:iii-viii. [PMID: 31400385 DOI: 10.1016/j.metabol.2019.153957] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 08/05/2019] [Indexed: 12/31/2022]
Affiliation(s)
- Olivia M Farr
- Division of Endocrinology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA 02215, United States of America.
| | - Christos S Mantzoros
- Division of Endocrinology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA 02215, United States of America; Section of Endocrinology, Boston VA Healthcare System/Harvard Medical School, Boston, MA 02130, United States of America
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16
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Liu K, Cao H, Dong X, Liu H, Wen Y, Mao H, Lu L, Yin Z. Polymorphisms of pro-opiomelanocortin gene and the association with reproduction traits in chickens. Anim Reprod Sci 2019; 210:106196. [PMID: 31635770 DOI: 10.1016/j.anireprosci.2019.106196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 09/17/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022]
Abstract
Pro-opiomelanocortin (POMC) is a member of prohormone family and has important functions in stress response, skin pigmentation, thermoregulation and reproduction. In this study, the single nucleotide polymorphisms (SNPs) of POMC gene exons were detected by direct sequencing in 317 Zhenning yellow chickens. The sequencing results indicated there were seven mutation sites (g.1140C > T, g.1185 T > C, g.2085 T > C, g.3566A > C, g.3572 G > A, g.3594 G > A and g.3628 G > A) and all of these were synonymous. Furthermore, seven haplotypes were formed and sixteen diplotypes were obtained. The associations between the POMC gene polymorphisms or diplotypes and reproduction traits were also analyzed. The association analysis results indicated that the SNP of g.1140C > T was associated with egg production at 300 d of age (E300), fertilization rate (FR), hatching rate of hatching eggs (HEHR) and hatching rate of fertilized eggs (FEHR; P < 0.05). The SNP of g.3566A>C was associated with FR (P < 0.05), SNP of g.3594G>A was associated with egg weight at 300d of age (EW300; P < 0.05), and SNP of g.3628G>A was associated with HEHR and FEHR (P < 0.01), respectively. Furthermore, chickens with H2H3 diplotype had greater EW300 and FR than those with H1H7 and H3H4 diplotypes (P < 0.05). These results indicate the expression of the POMC gene had significant genotype effects on the reproduction traits of Zhenning yellow chickens, and that the H2H3 diplotype could be used as a potential genetic marker to improve the reproduction traits in chicken breeding.
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Affiliation(s)
- Ke Liu
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Haiyue Cao
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Xinyang Dong
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Honghua Liu
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Yaya Wen
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Haiguang Mao
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
| | - Lei Lu
- Ningbo Zhenning Animal Husbandry Co. Ltd, Ningbo 315000, China
| | - Zhaozheng Yin
- College of Animal Sciences, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
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Kirsz K, Szczęsna M, Bocheńska A, Pietsch-Fulbiszewska A, Sowińska N, Kabała N, Zięba DA. Effects of central orexin A on gonadotropins and progesterone secretion in ewes during the luteal phase of the estrous cycle and during anestrus. Small Rumin Res 2019. [DOI: 10.1016/j.smallrumres.2019.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Morelli A, Filippi S, Comeglio P, Sarchielli E, Cellai I, Pallecchi M, Bartolucci G, Danza G, Rastrelli G, Corno C, Guarnieri G, Fuochi E, Vignozzi L, Maggi M. Physical activity counteracts metabolic syndrome-induced hypogonadotropic hypogonadism and erectile dysfunction in the rabbit. Am J Physiol Endocrinol Metab 2019; 316:E519-E535. [PMID: 30645174 DOI: 10.1152/ajpendo.00377.2018] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Metabolic syndrome (MetS) clusters cardiovascular and metabolic risk factors along with hypogonadism and erectile dysfunction. Lifestyle modifications including physical exercise (PhyEx) are well-known treatments for this condition. In this study, we analyzed the effect of PhyEx on hypothalamic-pituitary-testis axis and erectile function by use of an animal MetS model, previously established in rabbits fed a high-fat diet (HFD). Rabbits fed a regular diet (RD) were used as controls. A subset of both groups was trained on a treadmill. HFD rabbits showed typical MetS features, including HG (reduced T and LH) and impairment of erectile function. PhyEx in HFD rabbits completely restored plasma T and LH and the penile alterations. At testicular and hypothalamic levels, an HFD-induced inflammatory status was accompanied by reduced T synthesis and gonadotropin-releasing hormone (GnRH) immunopositivity, respectively. In the testis, PhyEx normalized HFD-related macrophage infiltration and increased the expression of steroidogenic enzymes and T synthesis. In the hypothalamus, PhyEx normalized HFD-induced gene expression changes related to inflammation and glucose metabolism, restored GnRH expression, particularly doubling mRNA levels, and regulated expression of molecules related to GnRH release (kisspeptin, dynorphin). Concerning MetS components, PhyEx significantly reduced circulating cholesterol and visceral fat. In multivariate analyses, cholesterol levels resulted as the main factor associated with MetS-related alterations in penile, testicular, and hypothalamic districts. In conclusion, our results show that PhyEx may rescue erectile function, exert anti-inflammatory effects on hypothalamus and testis, and increase LH levels and T production, thus supporting a primary role for lifestyle modification to combat MetS-associated hypogonadism and erectile dysfunction.
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Affiliation(s)
- Annamaria Morelli
- Department of Experimental and Clinical Medicine, University of Florence , Florence , Italy
| | - Sandra Filippi
- Interdepartmental Laboratory of Functional and Cellular Pharmacology of Reproduction, Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence , Florence , Italy
| | - Paolo Comeglio
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Erica Sarchielli
- Department of Experimental and Clinical Medicine, University of Florence , Florence , Italy
| | - Ilaria Cellai
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Marco Pallecchi
- Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Gianluca Bartolucci
- Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Giovanna Danza
- Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Giulia Rastrelli
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Chiara Corno
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Giulia Guarnieri
- Department of Experimental and Clinical Medicine, University of Florence , Florence , Italy
| | - Elisa Fuochi
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
| | - Linda Vignozzi
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
- Istituto Nazionale Biostrutture e Biosistemi , Rome , Italy
| | - Mario Maggi
- Sexual Medicine and Andrology Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence , Florence , Italy
- Istituto Nazionale Biostrutture e Biosistemi , Rome , Italy
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19
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Hill JW, Elias CF. Neuroanatomical Framework of the Metabolic Control of Reproduction. Physiol Rev 2019; 98:2349-2380. [PMID: 30109817 DOI: 10.1152/physrev.00033.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A minimum amount of energy is required for basic physiological processes, such as protein biosynthesis, thermoregulation, locomotion, cardiovascular function, and digestion. However, for reproductive function and survival of the species, extra energy stores are necessary. Production of sex hormones and gametes, pubertal development, pregnancy, lactation, and parental care all require energy reserves. Thus the physiological systems that control energy homeostasis and reproductive function coevolved in mammals to support both individual health and species subsistence. In this review, we aim to gather scientific knowledge produced by laboratories around the world on the role of the brain in integrating metabolism and reproduction. We describe essential neuronal networks, highlighting key nodes and potential downstream targets. Novel animal models and genetic tools have produced substantial advances, but critical gaps remain. In times of soaring worldwide obesity and metabolic dysfunction, understanding the mechanisms by which metabolic stress alters reproductive physiology has become crucial for human health.
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Affiliation(s)
- Jennifer W Hill
- Center for Diabetes and Endocrine Research, Departments of Physiology and Pharmacology and of Obstetrics and Gynecology, University of Toledo College of Medicine , Toledo, Ohio ; and Departments of Molecular and Integrative Physiology and of Obstetrics and Gynecology, University of Michigan , Ann Arbor, Michigan
| | - Carol F Elias
- Center for Diabetes and Endocrine Research, Departments of Physiology and Pharmacology and of Obstetrics and Gynecology, University of Toledo College of Medicine , Toledo, Ohio ; and Departments of Molecular and Integrative Physiology and of Obstetrics and Gynecology, University of Michigan , Ann Arbor, Michigan
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20
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21
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Scott CJ, Rose JL, Gunn AJ, McGrath BM. Kisspeptin and the regulation of the reproductive axis in domestic animals. J Endocrinol 2018; 240:JOE-18-0485.R1. [PMID: 30400056 DOI: 10.1530/joe-18-0485] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/09/2018] [Indexed: 11/08/2022]
Abstract
The control of reproductive processes involves the integration of a number of factors from the internal and external environment, with the final output signal of these processes being the pulsatile secretion of gonadotrophin releasing hormone (GnRH) from the hypothalamus. These factors include the feedback actions of sex steroids, feed intake and nutritional status, season/photoperiod, pheromones, age and stress. Understanding these factors and how they influence GnRH secretion and hence reproduction is important for the management of farm animals. There is evidence that the RF-amide neuropeptide, kisspeptin, may be involved in relaying the effects of these factors to the GnRH neurons. This paper will review the evidence from the common domestic animals (sheep, goats, cattle, horses and pigs), that kisspeptin neurons are i) regulated by the factors listed above, ii) contact GnRH neurons, and iii) involved in the regulation of GnRH/gonadotrophin secretion.
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Affiliation(s)
- Christopher J Scott
- C Scott, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Jessica L Rose
- J Rose, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Allan J Gunn
- A Gunn, School of Animal and Veterinary Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Briony M McGrath
- B McGrath, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
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22
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Zhai L, Zhao J, Zhu Y, Liu Q, Niu W, Liu C, Wang Y. Downregulation of leptin receptor and kisspeptin/GPR54 in the murine hypothalamus contributes to male hypogonadism caused by high-fat diet-induced obesity. Endocrine 2018; 62:195-206. [PMID: 29948931 DOI: 10.1007/s12020-018-1646-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 06/03/2018] [Indexed: 12/15/2022]
Abstract
PURPOSE 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.
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Affiliation(s)
- Lingling Zhai
- Department of Maternal and Child Health, School of Public Health, China Medical University, Shenyang, Liaoning, China
| | - Jian Zhao
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, Liaoning, China
| | - Yiming Zhu
- Seven-Year-program Clinical Medicine Students (100K71B), China Medical University, Shenyang, Liaoning, China
| | - Qiannan Liu
- Department of Maternal and Child Health, School of Public Health, China Medical University, Shenyang, Liaoning, China
| | - Wenhua Niu
- Department of Maternal and Child Health, School of Public Health, China Medical University, Shenyang, Liaoning, China
| | - Chengyin Liu
- Department of Maternal and Child Health, School of Public Health, China Medical University, Shenyang, Liaoning, China
| | - Yi Wang
- Environment and Non-communicable Disease Research Center, School of Public Health, China Medical University, Shenyang, Liaoning, China.
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23
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Nestor CC, Bedenbaugh MN, Hileman SM, Coolen LM, Lehman MN, Goodman RL. Regulation of GnRH pulsatility in ewes. Reproduction 2018; 156:R83-R99. [PMID: 29880718 DOI: 10.1530/rep-18-0127] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 06/07/2018] [Indexed: 01/21/2023]
Abstract
Early work in ewes provided a wealth of information on the physiological regulation of pulsatile gonadotropin-releasing hormone (GnRH) secretion by internal and external inputs. Identification of the neural systems involved, however, was limited by the lack of information on neural mechanisms underlying generation of GnRH pulses. Over the last decade, considerable evidence supported the hypothesis that a group of neurons in the arcuate nucleus that contain kisspeptin, neurokinin B and dynorphin (KNDy neurons) are responsible for synchronizing secretion of GnRH during each pulse in ewes. In this review, we describe our current understanding of the neural systems mediating the actions of ovarian steroids and three external inputs on GnRH pulsatility in light of the hypothesis that KNDy neurons play a key role in GnRH pulse generation. In breeding season adults, estradiol (E2) and progesterone decrease GnRH pulse amplitude and frequency, respectively, by actions on KNDy neurons, with E2 decreasing kisspeptin and progesterone increasing dynorphin release onto GnRH neurons. In pre-pubertal lambs, E2 inhibits GnRH pulse frequency by decreasing kisspeptin and increasing dynorphin release, actions that wane as the lamb matures to allow increased pulsatile GnRH secretion at puberty. Less is known about mediators of undernutrition and stress, although some evidence implicates kisspeptin and dynorphin, respectively, in the inhibition of GnRH pulse frequency by these factors. During the anoestrus, inhibitory photoperiod acting via melatonin activates A15 dopaminergic neurons that innervate KNDy neurons; E2 increases dopamine release from these neurons to inhibit KNDy neurons and suppress the frequency of kisspeptin and GnRH release.
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Affiliation(s)
- Casey C Nestor
- Department of Animal Science, North Carolina State University, Raleigh, North Carolina, USA
| | - Michelle N Bedenbaugh
- Department of Physiology, Pharmacology and Neuroscience, West Virginia University, Morgantown, West Virginia, USA
| | - Stanley M Hileman
- Department of Physiology, Pharmacology and Neuroscience, West Virginia University, Morgantown, West Virginia, USA
| | - Lique M Coolen
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Michael N Lehman
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, USA
| | - Robert L Goodman
- Department of Physiology, Pharmacology and Neuroscience, West Virginia University, Morgantown, West Virginia, USA
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Manfredi-Lozano M, Roa J, Tena-Sempere M. Connecting metabolism and gonadal function: Novel central neuropeptide pathways involved in the metabolic control of puberty and fertility. Front Neuroendocrinol 2018; 48:37-49. [PMID: 28754629 DOI: 10.1016/j.yfrne.2017.07.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/20/2017] [Accepted: 07/23/2017] [Indexed: 02/08/2023]
Abstract
Albeit essential for perpetuation of species, reproduction is an energy-demanding function that can be adjusted to body metabolic status. Reproductive maturation and function can be suppressed in conditions of energy deficit, but can be altered also in situations of persistent energy excess, e.g., morbid obesity. This metabolic-reproductive integration, of considerable pathophysiological relevance to explain different forms of perturbed puberty and sub/infertility, is implemented by the concerted action of numerous central and peripheral regulators, which impinge at different levels of the hypothalamic-pituitary-gonadal (HPG) axis, permitting a tight fit between nutritional/energy status and gonadal function. We summarize here the major physiological mechanisms whereby nutritional and metabolic cues modulate the maturation and function of the HPG axis. We will focus on recent progress on the major central neuropeptide pathways, including kisspeptins, neurokinin B and the products of POMC and NPY neurons, which convey metabolic information to GnRH neurons, as major hierarchical hub of our reproductive brain.
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Affiliation(s)
- M Manfredi-Lozano
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain; Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, INSERM, U1172, Lille, France
| | - J Roa
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain.
| | - M Tena-Sempere
- Instituto Maimónides de Investigación Biomédica de Cordoba (IMIBIC), Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, Spain; Hospital Universitario Reina Sofia, 14004 Cordoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Cordoba, Spain; FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.
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25
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Wahab F, Atika B, Ullah F, Shahab M, Behr R. Metabolic Impact on the Hypothalamic Kisspeptin-Kiss1r Signaling Pathway. Front Endocrinol (Lausanne) 2018; 9:123. [PMID: 29643834 PMCID: PMC5882778 DOI: 10.3389/fendo.2018.00123] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/12/2018] [Indexed: 12/12/2022] Open
Abstract
A large body of data has established the hypothalamic kisspeptin (KP) and its receptor, KISS1R, as major players in the activation of the neuroendocrine reproductive axis at the time of puberty and maintenance of reproductive capacity in the adult. Due to its strategic location, this ligand-receptor pair acts as an integrator of cues from gonadal steroids as well as of circadian and seasonal variation-related information on the reproductive axis. Besides these cues, the activity of the hypothalamic KP signaling is very sensitive to the current metabolic status of the body. In conditions of energy imbalance, either positive or negative, a number of alterations in the hypothalamic KP signaling pathway have been documented in different mammalian models including nonhuman primates and human. Deficiency of metabolic fuels during fasting causes a marked reduction of Kiss1 gene transcript levels in the hypothalamus and, hence, decreases the output of KP-containing neurons. Food intake or exogenous supply of metabolic cues, such as leptin, reverses metabolic insufficiency-related changes in the hypothalamic KP signaling. Likewise, alterations in Kiss1 expression have also been reported in other situations of energy imbalance like diabetes and obesity. Information related to the body's current metabolic status reaches to KP neurons both directly as well as indirectly via a complex network of other neurons. In this review article, we have provided an updated summary of the available literature on the regulation of the hypothalamic KP-Kiss1r signaling by metabolic cues. In particular, the potential mechanisms of metabolic impact on the hypothalamic KP-Kiss1r signaling, in light of available evidence, are discussed.
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Affiliation(s)
- Fazal Wahab
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
- *Correspondence: Fazal Wahab,
| | - Bibi Atika
- Department of Developmental Biology, Faculty of Biology, University of Göttingen, Göttingen, Germany
| | - Farhad Ullah
- Department of Zoology, Islamia College University, Peshawar, Pakistan
| | - Muhammad Shahab
- Laboratory of Reproductive Neuroendocrinology, Department of Animal Sciences, Faculty of Biological Sciences, Quiad-i-Azam University, Islamabad, Pakistan
| | - Rüdiger Behr
- Platform Degenerative Diseases, German Primate Center, Leibniz Institute for Primate Research, Göttingen, Germany
- DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
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True C, Takahashi D, Kirigiti M, Lindsley SR, Moctezuma C, Arik A, Smith MS, Kievit P, Grove KL. Arcuate nucleus neuropeptide coexpression and connections to gonadotrophin-releasing hormone neurones in the female rhesus macaque. J Neuroendocrinol 2017; 29:10.1111/jne.12491. [PMID: 28561903 PMCID: PMC5523807 DOI: 10.1111/jne.12491] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 12/11/2022]
Abstract
The underlying hypothalamic neurocircuitry by which metabolism and feeding regulates reproductive function has been well-studied in the rodent; however, recent data have demonstrated significant neuroanatomical differences in the human brain. The present study had three objectives, centred on arcuate nucleus neuropeptides regulating feeding and reproduction: (i) to characterise coexpression patterns in the female nonhuman primate; (ii) to establish whether these neuronal populations make potential contacts with gonadotophin-releasing hormone (GnRH) neurones; and (iii) to determine whether these contacts differ between the low and high GnRH-releasing states of pre-puberty and adulthood, respectively. Female nonhuman primates have several coexpression patterns of hypothalamic neuropeptides that differ from those reported in rodents. Cocaine- and amphetamine-regulated transcript (CART) is not coexpressed with pro-opiomelanocortin but instead with neuropeptide Y (NPY). CART is also expressed in a subpopulation of kisspeptin cells in the nonhuman primate, similar to observations in humans but diverging from findings in rodents. Very few GnRH-expressing neurones received close appositions from double-labelled kisspeptin/CART fibres; however, both single-labelled kisspeptin and CART fibres were in frequent apposition with GnRH neurones, with no differences between prepubertal and adult animals. NPY/agouti-related peptide (AgRP) coexpressing fibres contacted significantly more GnRH neurones in prepubertal animals than adults, consistent with increased NPY and AgRP mRNA observed in prepubertal animals. The findings of the present study detail significant differences in arcuate nucleus neuropeptide coexpression in the monkey compared to the rodent and are consistent with the hypothesis that arcuate nucleus NPY/AgRP neurones play an inhibitory role in controlling GnRH neuronal regulation in the prepubertal primate.
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Affiliation(s)
- C True
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - D Takahashi
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - M Kirigiti
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - S R Lindsley
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - C Moctezuma
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - A Arik
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - M S Smith
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - P Kievit
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - K L Grove
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
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Xu P, Zhu L, Saito K, Yang Y, Wang C, He Y, Yan X, Hyseni I, Tong Q, Xu Y. Melanocortin 4 receptor is not required for estrogenic regulations on energy homeostasis and reproduction. Metabolism 2017; 70:152-159. [PMID: 28403939 PMCID: PMC5407306 DOI: 10.1016/j.metabol.2016.12.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 12/31/2022]
Abstract
BACKGROUND Brain estrogen receptor-α (ERα) is essential for estrogenic regulation of energy homeostasis and reproduction. We previously showed that ERα expressed by pro-opiomelanocortin (POMC) neurons mediates estrogen's effects on food intake, body weight, negative regulation of hypothalamic-pituitary-gonadal axis (HPG axis) and fertility. RESULTS AND CONCLUSIONS We report here that global deletion of a key downstream receptor for POMC peptide, the melanocortin 4 receptor (MC4R), did not affect normal negative feedback regulation of estrogen on the HPG axis, estrous cyclicity and female fertility. Furthermore, loss of the MC4R did not influence estrogenic regulation on food intake and body weight. These results indicate that the MC4R is not required for estrogen's effects on metabolic and reproductive functions.
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Affiliation(s)
- Pingwen Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030.
| | - Liangru Zhu
- Department of Gastroenterology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, People's Republic of China
| | - Kenji Saito
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Yongjie Yang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Chunmei Wang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Yanlin He
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Xiaofeng Yan
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Ilirjana Hyseni
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030; Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030.
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Evans MC, Anderson GM. Neuroendocrine integration of nutritional signals on reproduction. J Mol Endocrinol 2017; 58:R107-R128. [PMID: 28057770 DOI: 10.1530/jme-16-0212] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 01/05/2017] [Indexed: 12/28/2022]
Abstract
Reproductive function in mammals is energetically costly and therefore tightly regulated by nutritional status. To enable this integration of metabolic and reproductive function, information regarding peripheral nutritional status must be relayed centrally to the gonadotropin-releasing hormone (GNRH) neurons that drive reproductive function. The metabolically relevant hormones leptin, insulin and ghrelin have been identified as key mediators of this 'metabolic control of fertility'. However, the neural circuitry through which they act to exert their control over GNRH drive remains incompletely understood. With the advent of Cre-LoxP technology, it has become possible to perform targeted gene-deletion and gene-rescue experiments and thus test the functional requirement and sufficiency, respectively, of discrete hormone-neuron signaling pathways in the metabolic control of reproductive function. This review discusses the findings from these investigations, and attempts to put them in context with what is known from clinical situations and wild-type animal models. What emerges from this discussion is clear evidence that the integration of nutritional signals on reproduction is complex and highly redundant, and therefore, surprisingly difficult to perturb. Consequently, the deletion of individual hormone-neuron signaling pathways often fails to cause reproductive phenotypes, despite strong evidence that the targeted pathway plays a role under normal physiological conditions. Although transgenic studies rarely reveal a critical role for discrete signaling pathways, they nevertheless prove to be a good strategy for identifying whether a targeted pathway is absolutely required, critically involved, sufficient or dispensable in the metabolic control of fertility.
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Affiliation(s)
- Maggie C Evans
- Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Greg M Anderson
- Centre for Neuroendocrinology and Department of AnatomyUniversity of Otago School of Medical Sciences, Dunedin, New Zealand
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Abstract
Kisspeptins are a group of peptide fragments encoded by the KISS1 gene in humans. They bind to kisspeptin receptors with equal efficacy. Kisspeptins and their receptors are expressed by neurons in the arcuate and anteroventral periventricular nuclei of the hypothalamus. Oestrogen mediates negative feedback of gonadotrophin-releasing hormone secretion via the arcuate nucleus. Conversely, it exerts positive feedback via the anteroventral periventricular nucleus. The sexual dimorphism of these nuclei accounts for the differential behaviour of the hypothalamic-pituitary-gonadal axis between genders. Kisspeptins are essential for reproductive function. Puberty is regulated by the maturation of kisspeptin neurons and by interactions between kisspeptins and leptin. Hence, kisspeptins have potential diagnostic and therapeutic applications. Kisspeptin agonists may be used to localise lesions in cases of hypothalamic-pituitary-gonadal axis dysfunction and evaluate the gonadotrophic potential of subfertile individuals. Kisspeptin antagonists may be useful as contraceptives in women, through the prevention of premature luteinisation during in vitro fertilisation, and in the treatment of sex steroid-dependent diseases and metastatic cancers.
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Affiliation(s)
- Eng Loon Tng
- Associate Consultant, Department of Medicine, Ng Teng Fong General Hospital, 1 Jurong East Street 21, Singapore 609606
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Sukhbaatar U, Kanasaki H, Mijiddorj T, Oride A, Hara T, Yamada T, Kyo S. Expression of GnRH and Kisspeptin in Primary Cultures of Fetal Rat Brain. Reprod Sci 2016; 24:227-233. [PMID: 27313117 DOI: 10.1177/1933719116653679] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Genetic studies in humans or in vivo studies using animals have shown that kisspeptin released from the hypothalamus controls secretion of gonadotropin-releasing hormone (GnRH) from GnRH neurons, and subsequently GnRH induces gonadotropin secretion from the anterior pituitary. Kisspeptin did not stimulate GnRH expression in the GnRH-producing cell line GT1-7. Thus, we cultured GnRH and kisspeptin neurons from whole fetal rat brain and examined the regulation of GnRH and kisspeptin. Expression of GnRH messenger RNA (mRNA) was unchanged by estradiol (E2) treatment in these primary cultures. In contrast, kisspeptin mRNA expression was increased 2.00 ± 0.23-fold by E2 treatment. When these cultures were stimulated by kisspeptin-10, GnRH mRNA was significantly increased up to 1.51 ± 0.35-fold. Expression of GnRH mRNA was also stimulated 1.84 ± 0.33-fold by GnRH itself. Interestingly, kisspeptin mRNA was significantly increased up to 2.43 ± 0.40-fold by kisspeptin alone. In addition, kisspeptin mRNA expression was significantly increased by stimulation with GnRH (1.46 ± 0.21-fold). Our observations demonstrated that kisspeptin, but not GnRH, was upregulated by E2 and that kisspeptin stimulates GnRH mRNA expression in primary cultures of whole fetal rat brain. Furthermore, GnRH and kisspeptin stimulate their own neurons to produce GnRH or kisspeptin, respectively.
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Affiliation(s)
- Unurjargal Sukhbaatar
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Haruhiko Kanasaki
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Tselmeg Mijiddorj
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Aki Oride
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Tomomi Hara
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
| | - Takaya Yamada
- 2 Department of Experimental Animals, Interdisciplinary Center for Science Research, Organization for Research, Shimane University, Izumo, Shimane, Japan
| | - Satoru Kyo
- 1 Department of Obstetrics and Gynecology, Faculty of Medicine, Shimane University School of Medicine, Izumo, Shimane, Japan
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Manfredi-Lozano M, Roa J, Ruiz-Pino F, Piet R, Garcia-Galiano D, Pineda R, Zamora A, Leon S, Sanchez-Garrido MA, Romero-Ruiz A, Dieguez C, Vazquez MJ, Herbison AE, Pinilla L, Tena-Sempere M. Defining a novel leptin-melanocortin-kisspeptin pathway involved in the metabolic control of puberty. Mol Metab 2016; 5:844-857. [PMID: 27688998 PMCID: PMC5034608 DOI: 10.1016/j.molmet.2016.08.003] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/02/2016] [Accepted: 08/05/2016] [Indexed: 11/24/2022] Open
Abstract
Objective Puberty is a key developmental phenomenon highly sensitive to metabolic modulation. Worrying trends of changes in the timing of puberty have been reported in humans. These might be linked to the escalating prevalence of childhood obesity and could have deleterious impacts on later (cardio-metabolic) health, but their underlying mechanisms remain unsolved. The neuropeptide α-MSH, made by POMC neurons, plays a key role in energy homeostasis by mediating the actions of leptin and likely participates in the control of reproduction. However, its role in the metabolic regulation of puberty and interplay with kisspeptin, an essential puberty-regulating neuropeptide encoded by Kiss1, remain largely unknown. We aim here to unveil the potential contribution of central α-MSH signaling in the metabolic control of puberty by addressing its role in mediating the pubertal effects of leptin and its potential interaction with kisspeptin. Methods Using wild type and genetically modified rodent models, we implemented pharmacological studies, expression analyses, electrophysiological recordings, and virogenetic approaches involving DREADD technology to selectively inhibit Kiss1 neurons, in order to interrogate the physiological role of a putative leptin→α-MSH→kisspeptin pathway in the metabolic control of puberty. Results Stimulation of central α-MSH signaling robustly activated the reproductive axis in pubertal rats, whereas chronic inhibition of melanocortin receptors MC3/4R, delayed puberty, and prevented the permissive effect of leptin on puberty onset. Central blockade of MC3/4R or genetic elimination of kisspeptin receptors from POMC neurons did not affect kisspeptin effects. Conversely, congenital ablation of kisspeptin receptors or inducible, DREADD-mediated inhibition of arcuate nucleus (ARC) Kiss1 neurons resulted in markedly attenuated gonadotropic responses to MC3/4R activation. Furthermore, close appositions were observed between POMC fibers and ARC Kiss1 neurons while blockade of α-MSH signaling suppressed Kiss1 expression in the ARC of pubertal rats. Conclusions Our physiological, virogenetic, and functional genomic studies document a novel α-MSH→kisspeptin→GnRH neuronal signaling pathway involved in transmitting the permissive effects of leptin on pubertal maturation, which is relevant for the metabolic (and, eventually, pharmacological) regulation of puberty onset. Puberty is highly sensitive to metabolic modulation and disturbed by child obesity. Altered puberty is linked to adverse metabolic health outcomes via unclear mechanisms. The POMC product, α-MSH, transmit leptin-mediated metabolic regulation of puberty. A novel α-MSH→kisspeptin→GnRH signaling pathway is involved in the control of puberty This pathway is important for the metabolic (and pharmacologic) control of puberty.
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Affiliation(s)
- Maria Manfredi-Lozano
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain
| | - Juan Roa
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain.
| | - Francisco Ruiz-Pino
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain
| | - Richard Piet
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - David Garcia-Galiano
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain
| | - Rafael Pineda
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain
| | - Aurora Zamora
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain
| | - Silvia Leon
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain
| | - Miguel A Sanchez-Garrido
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain
| | - Antonio Romero-Ruiz
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain
| | - Carlos Dieguez
- Department of Physiology, CIMUS, University of Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Maria Jesus Vazquez
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Leonor Pinilla
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain
| | - Manuel Tena-Sempere
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), 14004 Córdoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, 14004 Córdoba, Spain; Hospital Universitario Reina Sofia (HURS), 14004 Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Córdoba, Spain.
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Gastric Bypass Surgery but not Caloric Restriction Improves Reproductive Function in Obese Mice. Obes Surg 2016; 26:467-73. [PMID: 26667161 DOI: 10.1007/s11695-015-2009-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In women, obesity is associated with decrements in reproductive health that are improved with weight loss. Due to the difficulty of maintaining weight loss through lifestyle interventions, surgical interventions have become popular treatments for obesity. We examined how weight loss induced by Roux-en Y gastric bypass surgery (RYGB) or calorie restriction impacted expression of hypothalamic genes related to energy intake and reproduction. RYGB and calorie restriction induced equivalent weight loss; however, expression of the anorexigenic melanocortin pathway decreased only in calorie restricted mice. Serum estradiol concentrations were lower in calorie restricted mice relative to RYGB during proestrous, suggesting that RYGB maintained normal estrous cycling. Thus, the effects of RYGB for female mice, and possibly humans, extend beyond weight loss to include enhanced reproductive health.
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Clarke IJ, Arbabi L. New concepts of the central control of reproduction, integrating influence of stress, metabolic state, and season. Domest Anim Endocrinol 2016; 56 Suppl:S165-79. [PMID: 27345314 DOI: 10.1016/j.domaniend.2016.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 03/02/2016] [Accepted: 03/02/2016] [Indexed: 10/21/2022]
Abstract
Gonadotropin releasing hormone is the primary driver of reproductive function and pulsatile GnRH secretion from the brain causes the synthesis and secretion of LH and FSH from the pituitary gland. Recent work has revealed that the secretion of GnRH is controlled at the level of the GnRH secretory terminals in the median eminence. At this level, projections of kisspeptin cells from the arcuate nucleus of the hypothalamus are seen to be closely associated with fibers and terminals of GnRH cells. Direct application of kisspeptin into the median eminence causes release of GnRH. The kisspeptin cells are activated at the time of a natural "pulse" secretion of GnRH, as reflected in the secretion of LH. This appears to be due to input to the kisspeptin cells from glutamatergic cells in the basal hypothalamus, indicating that more than 1 neural element is involved in the secretion of GnRH. Because the GnRH secretory terminals are outside the blood-brain barrier, factors such as kisspeptin may be administered systemically to cause GnRH secretion; this offers opportunities for manipulation of the reproductive axis using factors that do not cross the blood-brain barrier. In particular, kisspeptin or analogs of the same may be used to activate reproduction in the nonbreeding season of domestic animals. Another brain peptide that influences reproductive function is gonadotropin inhibitory hormone (GnIH). Work in sheep shows that this peptide acts on GnRH neuronal perikarya, but projections to the median eminence also allow secretion into the hypophysial portal blood and action of GnIH on pituitary gonadotropes. GnIH cells are upregulated in anestrus, and infusion of GnIH can block the ovulatory surge in GnRH and/or LH secretion. Metabolic status may also affect the secretion of reproduction, and this could involve action of gut peptides and leptin. Neuropeptide Y and Y-receptor ligands have a negative impact on reproduction, and Neuropeptide Y production is markedly increased in negative energy balance; this may be the cause of lowered GnRH and gonadotropin secretion in this state. There is a complex interaction between appetite-regulating peptide neurons and kisspeptin neurons that enables the former to regulate the latter both positively and negatively. In terms of how GnRH secretion is reduced during stress, recent data indicate that GnIH cells are integrally involved, with increased input to the GnRH cells. The secretion of GnIH into the portal blood is not increased during stress, so the negative effect is most likely effected at the level of GnRH neuronal cell bodies.
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Affiliation(s)
- I J Clarke
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.
| | - L Arbabi
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia
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Perry GA. Factors affecting puberty in replacement beef heifers. Theriogenology 2016; 86:373-8. [PMID: 27160450 DOI: 10.1016/j.theriogenology.2016.04.051] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/25/2016] [Accepted: 03/14/2016] [Indexed: 01/04/2023]
Abstract
Puberty is defined as when ovulation is accompanied by visual signs of estrus and subsequent normal luteal function. Age at puberty is an important trait in relation to reproductive success, productive life span, and profitability in beef operations. Although puberty and initiation of normal estrous cycles are complex events that require maturation of the hypothalamic-pituitary-ovarian axis, it has been well documented that nutrition, age, and genetics are regulators of age at puberty. However, their role is mainly as regulators of the endocrine maturation that must occur for sustained ovarian cyclicity to be initiated. Increased growth rate between 4 and 7 months of age is apparently sufficient to induce early puberty, and this increased growth rate decreased the negative feedback of estradiol on LH secretion during the prepubertal period. As puberty approaches, a progressive decrease in the negative feedback of estradiol on GnRH secretion allows increased pulse frequency of LH, thus stimulating follicular growth and increased estradiol production. In addition, expression of estrogen receptors in the anterior hypothalamus and ventromedial nucleus is negatively correlated with LH pulse frequency. Although a significant number of genes and pathways are involved in neuromaturation for the initiation of normal estrous cycles, the inhibitory effects of neuropeptide Y on GnRH/LH release appear to decrease, and the stimulatory effect of melanocyte-stimulating hormone alpha on GnRH appears to increase as puberty approaches. Thus, a thorough understanding of the metabolic and neuroendocrine changes that occur to initiate normal estrous cycles is needed to facilitate management of the important reproductive event.
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Affiliation(s)
- G A Perry
- South Dakota State University, Department of Animal Science, Brookings, USA.
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Abstract
The endocrine hypothalamus constitutes those cells which project to the median eminence and secrete neurohormones into the hypophysial portal blood to act on cells of the anterior pituitary gland. The entire endocrine system is controlled by these peptides. In turn, the hypothalamic neuroendocrine cells are regulated by feedback signals from the endocrine glands and other circulating factors. The neuroendocrine cells are found in specific regions of the hypothalamus and are regulated by afferents from higher brain centers. Integrated function is clearly complex and the networks between and amongst the neuroendocrine cells allows fine control to achieve homeostasis. The entry of hormones and other factors into the brain, either via the cerebrospinal fluid or through fenestrated capillaries (in the basal hypothalamus) is important because it influences the extent to which feedback regulation may be imposed. Recent evidence of the passage of factors from the pars tuberalis and the median eminence casts a new layer in our understanding of neuroendocrine regulation. The function of neuroendocrine cells and the means by which pulsatile secretion is achieved is best understood for the close relationship between gonadotropin releasing hormone and luteinizing hormone, which is reviewed in detail. The secretion of other neurohormones is less rigid, so the relationship between hypothalamic secretion and the relevant pituitary hormones is more complex.
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Affiliation(s)
- I J Clarke
- Monash University, Department of Physiology, Clayton, Australia
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Cardoso RC, Alves BRC, Sharpton SM, Williams GL, Amstalden M. Nutritional Programming of Accelerated Puberty in Heifers: Involvement of Pro-Opiomelanocortin Neurones in the Arcuate Nucleus. J Neuroendocrinol 2015; 27:647-57. [PMID: 25944025 DOI: 10.1111/jne.12291] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 11/27/2022]
Abstract
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.
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Affiliation(s)
- R C Cardoso
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, TX, USA
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - B R C Alves
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - S M Sharpton
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - G L Williams
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, TX, USA
- Department of Animal Science, Texas A&M University, College Station, TX, USA
| | - M Amstalden
- Department of Animal Science, Texas A&M University, College Station, TX, USA
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López M, Tena-Sempere M. Estrogens and the control of energy homeostasis: a brain perspective. Trends Endocrinol Metab 2015; 26:411-21. [PMID: 26126705 DOI: 10.1016/j.tem.2015.06.003] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/29/2015] [Accepted: 06/01/2015] [Indexed: 01/09/2023]
Abstract
Despite their prominent roles in the control of reproduction, estrogens pervade many other bodily functions. Key metabolic pathways display marked sexual differences, and estrogens are potent modulators of energy balance, as evidenced in extreme conditions of estrogen deficiency characterized by hyperphagia and decreased energy expenditure, and leading to obesity. Compelling evidence has recently demonstrated that, in addition to their peripheral effects, the actions of estrogens on energy homeostasis are exerted at central levels, to regulate almost every key aspect of metabolic homeostasis, from feeding to energy expenditure, to glucose and lipid metabolism. We review herein the state-of-the-art of the role of estrogens in the regulation of energy balance, with a focus on their central effects and modes of action.
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Affiliation(s)
- Miguel López
- Department of Physiology, Faculty of Medicine and CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Cordoba, Spain.
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, 14004 Cordoba, Spain; Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Reina Sofía, 14004 Córdoba, Spain; FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.
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Merkley CM, Coolen LM, Goodman RL, Lehman MN. Evidence for Changes in Numbers of Synaptic Inputs onto KNDy and GnRH Neurones during the Preovulatory LH Surge in the Ewe. J Neuroendocrinol 2015; 27:624-35. [PMID: 25976424 PMCID: PMC4809364 DOI: 10.1111/jne.12293] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/19/2015] [Accepted: 05/10/2015] [Indexed: 11/28/2022]
Abstract
Kisspeptin neurones located in the arcuate nucleus (ARC) and preoptic area (POA) are critical mediators of gonadal steroid feedback onto gonadotrophin-releasing hormone (GnRH) neurones. ARC kisspeptin cells that co-localise neurokinin B (NKB) and dynorphin (Dyn), are collectively referred to as KNDy (Kisspeptin/NKB/Dyn) neurones, and have been shown in mice to also co-express the vesicular glutamate transporter, vGlut2, an established glutamatergic marker. The ARC in rodents has long been known as a site of hormone-induced neuroplasticity, and changes in synaptic inputs to ARC neurones in rodents occur over the oestrous cycle. Based on this evidence, the the present study aimed to examine possible changes across the ovine oestrous cycle in synaptic inputs onto kisspeptin cells in the ARC (KNDy) and POA, and inputs onto GnRH neurones. Gonadal-intact breeding season ewes were perfused using 4% paraformaldehyde during either the luteal or follicular phase of the oestrous cycle, with the latter group killed at the time of the luteinising hormone (LH) surge. Hypothalamic sections were processed for triple-label immunodetection of kisspeptin/vGlut2/synaptophysin or kisspeptin/vGlut2/GnRH. The total numbers of synaptophysin- and vGlut2-positive inputs to ARC KNDy neurones were significantly increased at the time of the LH surge compared to the luteal phase; because these did not contain kisspeptin, they do not arise from KNDy neurones. By contrast to the ARC, the total number of synaptophysin-positive inputs onto POA kisspeptin neurones did not differ between luteal phase and surge animals. The total number of kisspeptin and vGlut2 inputs onto GnRH neurones in the mediobasal hypothalamus (MBH) was also increased during the LH surge, and could be attributed to an increase in the number of KNDy (double-labelled kisspeptin + vGlut2) inputs. Taken together, these results provide novel evidence of synaptic plasticity at the level of inputs onto KNDy and GnRH neurones during the ovine oestrous cycle. Such changes may contribute to the generation of the preovulatory GnRH/LH surge.
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Affiliation(s)
- Christina M. Merkley
- Neuroscience Graduate Program, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Lique M. Coolen
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Robert L. Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia, 26506, USA
| | - Michael N. Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
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Clarke H, Dhillo WS, Jayasena CN. Comprehensive Review on Kisspeptin and Its Role in Reproductive Disorders. Endocrinol Metab (Seoul) 2015; 30:124-41. [PMID: 26194072 PMCID: PMC4508256 DOI: 10.3803/enm.2015.30.2.124] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/05/2015] [Accepted: 01/12/2015] [Indexed: 02/05/2023] Open
Abstract
Kisspeptin has recently emerged as a key regulator of the mammalian reproductive axis. It is known that kisspeptin, acting centrally via the kisspeptin receptor, stimulates secretion of gonadotrophin releasing hormone (GnRH). Loss of kisspeptin signaling causes hypogonadotrophic hypogonadism in humans and other mammals. Kisspeptin interacts with other neuropeptides such as neurokinin B and dynorphin, to regulate GnRH pulse generation. In addition, a growing body of evidence suggests that kisspeptin signaling be regulated by nutritional status and stress. Kisspeptin may also represent a novel potential therapeutic target in the treatment of fertility disorders. Early human studies suggest that peripheral exogenous kisspeptin administration stimulates gonadotrophin release in healthy adults and in patients with certain forms of infertility. This review aims to concisely summarize what is known about kisspeptin as a regulator of reproductive function, and provide an update on recent advances within this field.
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Affiliation(s)
- Holly Clarke
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - Waljit S Dhillo
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, UK
| | - Channa N Jayasena
- Department of Investigative Medicine, Hammersmith Hospital, Imperial College London, London, UK.
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Wahab F, Shahab M, Behr R. The involvement of gonadotropin inhibitory hormone and kisspeptin in the metabolic regulation of reproduction. J Endocrinol 2015; 225:R49-66. [PMID: 25957191 DOI: 10.1530/joe-14-0688] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recently, kisspeptin (KP) and gonadotropin inhibitory hormone (GnIH), two counteracting neuropeptides, have been acknowledged as significant regulators of reproductive function. KP stimulates reproduction while GnIH inhibits it. These two neuropeptides seem to be pivotal for the modulation of reproductive activity in response to internal and external cues. It is well-documented that the current metabolic status of the body is closely linked to its reproductive output. However, how reproductive function is regulated by the body's energy status is less clear. Recent studies have suggested an active participation of hypothalamic KP and GnIH in the modulation of reproductive function according to available metabolic cues. Expression of KISS1, the KP encoding gene, is decreased while expression of RFRP (NPVF), the gene encoding GnIH, is increased in metabolic deficiency conditions. The lower levels of KP, as suggested by a decrease in KISS1 gene mRNA expression, during metabolic deficiency can be corrected by administration of exogenous KP, which leads to an increase in reproductive hormone levels. Likewise, administration of RF9, a GnIH receptor antagonist, can reverse the inhibitory effect of fasting on testosterone in monkeys. Together, it is likely that the integrated function of both these hypothalamic neuropeptides works as a reproductive output regulator in response to a change in metabolic status. In this review, we have summarized literature from nonprimate and primate studies that demonstrate the involvement of KP and GnIH in the metabolic regulation of reproduction.
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Affiliation(s)
- F Wahab
- Stem Cell Biology Unit Leibniz Institute for Primate Research, German Primate Center, Kellnerweg 4, D-37077 Göttingen, Germany Laboratory of Reproductive Neuroendocrinology Department of Animal Sciences, Faculty of Biological Sciences, Quiad-i-Azam University, Islamabad, Pakistan
| | - M Shahab
- Stem Cell Biology Unit Leibniz Institute for Primate Research, German Primate Center, Kellnerweg 4, D-37077 Göttingen, Germany Laboratory of Reproductive Neuroendocrinology Department of Animal Sciences, Faculty of Biological Sciences, Quiad-i-Azam University, Islamabad, Pakistan
| | - R Behr
- Stem Cell Biology Unit Leibniz Institute for Primate Research, German Primate Center, Kellnerweg 4, D-37077 Göttingen, Germany Laboratory of Reproductive Neuroendocrinology Department of Animal Sciences, Faculty of Biological Sciences, Quiad-i-Azam University, Islamabad, Pakistan
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Ezzat A, Pereira A, Clarke IJ. Kisspeptin is a component of the pulse generator for GnRH secretion in female sheep but not the pulse generator. Endocrinology 2015; 156:1828-37. [PMID: 25710282 DOI: 10.1210/en.2014-1756] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We tested the hypothesis that kisspeptin cells constitute the "pulse generator" for GnRH secretion. In ewes, we determined whether iv administered kisspeptin elicits a secretory pulse of LH in anaesthetized, sex-steroid suppressed ovariectomized ewes. A response was seen in both anaesthetized and conscious animals, which was not associated with induction of c-Fos labeling in GnRH cells, supporting the notion that kisspeptin acts on the neurosecretory GnRH terminals. Response was lower in the anaesthetized animals, suggesting that some nonkisspeptin elements may be involved in GnRH responses. Microinjection of kisspeptin (100 nmol) into the median eminence of conscious ewes elicited a pulse of LH, indicating that kisspeptin acts at this level to cause GnRH secretion. To determine which cells are activated at the time of GnRH secretion, we blood sampled 18 ewes during the luteal phase of the estrous cycle and harvested brains after 3 hours. Three of these ewes displayed a pulse of LH within 30 minutes of euthanasia. An increase in c-Fos labeling was seen in kisspeptin and glutamate cells of the arcuate nucleus but not in GnRH neurons, preoptic kisspeptin neurons, or preoptic glutamate neurons. Immunohistochemistry in 4 hypothalami showed that 72% of arcuate kisspeptin cells receive glutamatergic input. These data support the concept that the kisspeptin cells of the arcuate nucleus drive pulsatile secretion of GnRH at the level of the median eminence, but this may involve "upstream" input from glutamate cells. We conclude that the pulse generator for GnRH secretion involves more than 1 element.
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Affiliation(s)
- Ahmed Ezzat
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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Affiliation(s)
- Laurence Dufourny
- UMR7247, Physiologie de la Reproduction et des comportements, INRA-CNRS-Université de Tours-IFCE, 37380 Nouzilly, France
| | - Massimiliano Beltramo
- UMR7247, Physiologie de la Reproduction et des comportements, INRA-CNRS-Université de Tours-IFCE, 37380 Nouzilly, France
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Ratra DV, Elias CF. Chemical identity of hypothalamic neurons engaged by leptin in reproductive control. J Chem Neuroanat 2014; 61-62:233-8. [PMID: 24915437 DOI: 10.1016/j.jchemneu.2014.05.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 05/29/2014] [Accepted: 05/31/2014] [Indexed: 01/31/2023]
Abstract
The adipocyte-derived hormone leptin plays a critical role as a metabolic cue for the reproductive system. Conditions of low leptin levels observed in negative energy balance and loss-of-function mutations of leptin or leptin receptor genes are characterized by decreased fertility. In recent years, advances have been made for identifying possible hypothalamic neurons relaying leptin's neuroendocrine control of reproductive function. Studies from different laboratories have demonstrated that leptin action in the hypothalamo-pituitary-gonadal (HPG) axis is exerted via hypothalamic interneurons regulating gonadotropin-releasing hormone (GnRH) cells, oppose to direct action on GnRH neurons. Following this observation, studies focused on identifying leptin responsive interneurons. Using a Cre-loxP system to re-express or delete the leptin receptor long form (LepRb) from kisspeptin neurons, our laboratory found that leptin's action on kiss1 cells is neither required nor sufficient for leptin's role in reproductive function. Endogenous re-expression of LepRb however, in glutamatergic neurons of the ventral premammilary nucleus (PMV) or ablation of agouti-related protein (AgRP) neurons from leptin signaling-deficient mice are both sufficient to induce puberty and improve fertility. Recent studies have also shown that leptin action in first order GABAergic neurons is required for fertility. Together, these studies begin to delineate key neuronal populations involved in leptin's action in reproduction. In this review, we discuss recent advances made in the field and highlight the questions yet to be answered.
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Affiliation(s)
- Dhirender V Ratra
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Carol F Elias
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA; Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, MI 48109, USA.
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Amstalden M, Cardoso RC, Alves BRC, Williams GL. Reproduction Symposium: hypothalamic neuropeptides and the nutritional programming of puberty in heifers. J Anim Sci 2014; 92:3211-22. [PMID: 24894003 DOI: 10.2527/jas.2014-7808] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Nutrition during the juvenile period has a major impact on timing reproductive maturity in heifers. Restricted growth delays puberty, whereas elevated BW gain advances the onset of puberty. The initiation of high-frequency episodic release of GnRH and, consequently, LH during the peripubertal period is crucial for maturation of the reproductive axis and establishment of normal estrous cycles. Nutritional signals are perceived by metabolic-sensing cells in the hypothalamus, which interact with estradiol-receptive neurons to regulate the secretory activity of GnRH neurons. The orexigenic peptide, neuropeptide Y (NPY), and the anorexigenic peptide derived from the proopiomelanocortin (POMC) gene, melanocyte-stimulating hormone α (αMSH), are believed to be major afferent pathways that transmit inhibitory (NPY) and excitatory (αMSH) inputs to GnRH neurons. The neuropeptide kisspeptin is considered a major stimulator of GnRH secretion and has been shown to mediate estradiol's effect on GnRH neuronal activity. Kisspeptin may also integrate the neuronal pathways mediating the metabolic and gonadal steroid hormone control of gonadotropin secretion. Recent studies in our laboratories indicate that functional and structural changes in the pathways involving NPY, POMC, and kisspeptin neurons occur in response to high rates of BW gain during the juvenile period in heifers. Changes include regulation of expression in NPY, POMC, and KISS1 and plasticity in the neuronal projections to GnRH neurons and within the neuronal network comprising these cells. Moreover, an intricate pattern of differential gene expression in the arcuate nucleus of the hypothalamus occurs in response to feeding high concentrate diets that promote elevated BW gain. Genes involved include those controlling feeding intake and cell metabolism, neuronal growth and remodeling, and synaptic transmission. Characterizing the cellular pathways and molecular networks involved in the mechanisms that control the timing of pubertal onset will assist in improving existing strategies and facilitate the development of novel approaches to program puberty in heifers. These include the use of diets that elevate BW gain during strategic periods of prepubertal development.
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Affiliation(s)
- M Amstalden
- Department of Animal Science, Texas A&M University, College Station 77843
| | - R C Cardoso
- Department of Animal Science, Texas A&M University, College Station 77843 Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102
| | - B R C Alves
- Department of Animal Science, Texas A&M University, College Station 77843
| | - G L Williams
- Department of Animal Science, Texas A&M University, College Station 77843 Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102
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Abstract
Kisspeptin is vital for the neuroendocrine regulation of GNRH secretion. Kisspeptin neurons are now recognized as a central pathway responsible for conveying key homeostatic information to GNRH neurons. This pathway is likely to mediate the well-established link between energy balance and reproductive function. Thus, in states of severely altered energy balance (either negative or positive), fertility is compromised, as isKiss1expression in the arcuate nucleus. A number of metabolic modulators have been proposed as regulators of kisspeptin neurons including leptin, ghrelin, pro-opiomelanocortin (POMC), and neuropeptide Y (NPY). Whether these regulate kisspeptin neurons directly or indirectly will be discussed. Moreover, whether the stimulatory role of leptin on reproduction is mediated by kisspeptin directly will be questioned. Furthermore, in addition to being expressed in GNRH neurons, the kisspeptin receptor (Kiss1r) is also expressed in other areas of the brain, as well as in the periphery, suggesting alternative roles for kisspeptin signaling outside of reproduction. Interestingly, kisspeptin neurons are anatomically linked to, and can directly excite, anorexigenic POMC neurons and indirectly inhibit orexigenic NPY neurons. Thus, kisspeptin may have a direct role in regulating energy balance. Although data fromKiss1rknockout and WT mice found no differences in body weight, recent data indicate that kisspeptin may still play a role in food intake and glucose homeostasis. Thus, in addition to regulating reproduction, and mediating the effect of energy balance on reproductive function, kisspeptin signaling may also be a direct regulator of metabolism.
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Jacobi JS, Coleman HA, Enriori PJ, Parkington HC, Li Q, Pereira A, Cowley MA, Clarke IJ. Paradoxical effect of gonadotrophin-inhibiting hormone to negatively regulate neuropeptide Y neurones in mouse arcuate nucleus. J Neuroendocrinol 2013; 25:1308-1317. [PMID: 24118324 DOI: 10.1111/jne.12114] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 09/27/2013] [Accepted: 10/09/2013] [Indexed: 12/23/2022]
Abstract
Regulation of reproduction and energy homeostasis are linked, although our understanding of the central neural mechanisms subserving this connection is incomplete. Gonadotrophin-inhibiting hormone (GnIH) is a neuropeptide that negatively regulates reproduction and stimulates food intake. Neuropeptide Y (NPY) and products of the pro-opiomelanocortin (POMC) precursor (β-endorphin melanocortins) are appetite regulating peptides produced in the neurones of the arcuate nucleus; these peptides also regulate reproduction. In the present study, we determined the effects of GnIH on NPY and POMC neurones. Using brain slices from mice with transgenes for fluorescent tags in the two types of neurone and patch clamp electrophysiology, a predominant inhibitory effect of GnIH was observed. GnIH (100 nM) inhibited the firing rate in POMC cells, confirming the results of previous studies and consistent with the stimulatory effect of GnIH on food intake. Paradoxically (i.e. because both GnIH and NPY stimulate food intake), GnIH also had a predominantly inhibitory effect on action potential activity in NPY cells. GnIH also inhibited the secretion of NPY and α-melanocyte-stimulating hormone secretion in incubated hypothalamic blocks. GnIH (100 ng) injected into the cerebral ventricles of mice did not increase the number of NPY cells that were positively immunostained for c-Fos. Finally, dual label immunocytochemistry showed that 20% of NPY neurones had close contacts from GnIH fibres/varicosities. In conclusion, we confirm a negative effect of GnIH on POMC cells and demonstrate a paradoxical reduction of electrophysiological and functional activity in NPY cells.
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Affiliation(s)
- J S Jacobi
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - H A Coleman
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - P J Enriori
- Department of Physiology, Monash University, Clayton, VIC, Australia
- Monash Obesity and Diabetes Institute, Monash University, Clayton, VIC, Australia
| | - H C Parkington
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - Q Li
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - A Pereira
- Department of Physiology, Monash University, Clayton, VIC, Australia
| | - M A Cowley
- Department of Physiology, Monash University, Clayton, VIC, Australia
- Monash Obesity and Diabetes Institute, Monash University, Clayton, VIC, Australia
| | - I J Clarke
- Department of Physiology, Monash University, Clayton, VIC, Australia
- Monash Obesity and Diabetes Institute, Monash University, Clayton, VIC, Australia
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48
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Comninos AN, Jayasena CN, Dhillo WS. The relationship between gut and adipose hormones, and reproduction. Hum Reprod Update 2013; 20:153-74. [PMID: 24173881 DOI: 10.1093/humupd/dmt033] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Reproductive function is tightly regulated by nutritional status. Indeed, it has been well described that undernutrition or obesity can lead to subfertility or infertility in humans. The common regulatory pathways which control energy homeostasis and reproductive function have, to date, been poorly understood due to limited studies or inconclusive data. However, gut hormones and adipose tissue hormones have recently emerged as potential regulators of both energy homeostasis and reproductive function. METHODS A PubMed search was performed using keywords related to gut and adipose hormones and associated with keywords related to reproduction. RESULTS Currently available evidence that gut (ghrelin, obestatin, insulin, peptide YY, glucagon-like peptide-1, glucose-dependent insulinotropic peptide, oxyntomodulin, cholecystokinin) and adipose hormones (leptin, adiponectin, resistin, omentin, chemerin) interact with the reproductive axis is presented. The extent, site and direction of their effects on the reproductive axis are variable and also vary depending on species, sex and pubertal stage. CONCLUSIONS Gut and adipose hormones interact with the reproductive axis as well as with each other. While leptin and insulin have stimulatory effects and ghrelin has inhibitory effects on hypothalamic GnRH secretion, there is increasing evidence for their roles in other sites of the reproductive axis as well as evidence for the roles of other gut and adipose hormones in the complex interplay between nutrition and reproduction. As our understanding improves, so will our ability to identify and design novel therapeutic options for reproductive disorders and accompanying metabolic disorders.
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Affiliation(s)
- Alexander N Comninos
- Department of Investigative Medicine, Imperial College London, 6th Floor Commonwealth Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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Tanaka T, Ohkura S, Wakabayashi Y, Kuroiwa T, Nagai K, Endo N, Tanaka A, Matsui H, Kusaka M, Okamura H. Differential effects of continuous exposure to the investigational metastin/kisspeptin analog TAK-683 on pulsatile and surge mode secretion of luteinizing hormone in ovariectomized goats. J Reprod Dev 2013; 59:563-8. [PMID: 24047956 PMCID: PMC3934154 DOI: 10.1262/jrd.2013-060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The aim of the present study was to determine if the estradiol-induced luteinizing
hormone (LH) surge is influenced by the constant exposure to TAK-683, an
investigational metastin/kisspeptin analog, that had been established to depress the
pulsatile gonadotropin-releasing hormone (GnRH) and LH secretion in goats.
Ovariectomized goats subcutaneously received TAK-683 (TAK-683 group, n=6) or vehicle
(control group, n=6) constantly via subcutaneous implantation of an osmotic pump.
Five days after the start of the treatment, estradiol was infused intravenously in
both groups to evaluate the effects on the LH surge. Blood samples were collected at
6-min intervals for 4 h prior to the initiation of either the TAK-683 treatment or
the estradiol infusion, to determine the profiles of pulsatile LH secretion. They
were also collected at 2-h intervals from –4 h to 32 h after the start of estradiol
infusion for analysis of LH surges. The frequency and mean concentrations of LH
pulses in the TAK-683 group were remarkably suppressed 5 days after the start of
TAK-683 treatment compared with those of the control group (P<0.05). On the other
hand, a clear LH surge was observed in all animals of both groups. There were no
significant differences in the LH concentrations for surge peak and the peak time of
the LH surge between the TAK-683 and control groups. These findings suggest that the
effects of continuous exposure to kisspeptin or its analog on the mechanism(s) that
regulates the pulsatile and surge mode secretion of GnRH/LH are different in
goats.
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Affiliation(s)
- Tomomi Tanaka
- Laboratory of Veterinary Reproduction, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
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Daniel JA, Foradori CD, Whitlock BK, Sartin JL. Hypothalamic Integration of Nutrient Status and Reproduction in the Sheep. Reprod Domest Anim 2013; 48 Suppl 1:44-52. [DOI: 10.1111/rda.12227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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