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Nakamura S, Sasaki T, Uenoyama Y, Inoue N, Nakanishi M, Yamada K, Morishima A, Suzumura R, Kitagawa Y, Morita Y, Ohkura S, Tsukamura H. Raphe glucose-sensing serotonergic neurons stimulate KNDy neurons to enhance LH pulses via 5HT2CR: rat and goat studies. Sci Rep 2024; 14:10190. [PMID: 38702366 PMCID: PMC11068885 DOI: 10.1038/s41598-024-58470-4] [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: 11/02/2023] [Accepted: 03/29/2024] [Indexed: 05/06/2024] Open
Abstract
Dysfunction of central serotonergic neurons is known to cause depressive disorders in humans, who often show reproductive and/or glucose metabolism disorders. This study examined whether dorsal raphe (DR) serotonergic neurons sense high glucose availability to upregulate reproductive function via activating hypothalamic arcuate (ARC) kisspeptin neurons (= KNDy neurons), a dominant stimulator of gonadotropin-releasing hormone (GnRH)/gonadotropin pulses, using female rats and goats. RNA-seq and histological analysis revealed that stimulatory serotonin-2C receptor (5HT2CR) was mainly expressed in the KNDy neurons in female rats. The serotonergic reuptake inhibitor administration into the mediobasal hypothalamus (MBH), including the ARC, significantly blocked glucoprivic suppression of luteinizing hormone (LH) pulses and hyperglycemia induced by intravenous 2-deoxy-D-glucose (2DG) administration in female rats. A local infusion of glucose into the DR significantly increased in vivo serotonin release in the MBH and partly restored LH pulses and hyperglycemia in the 2DG-treated female rats. Furthermore, central administration of serotonin or a 5HT2CR agonist immediately evoked GnRH pulse generator activity, and central 5HT2CR antagonism blocked the serotonin-induced facilitation of GnRH pulse generator activity in ovariectomized goats. These results suggest that DR serotonergic neurons sense high glucose availability to reduce gluconeogenesis and upregulate reproductive function by activating GnRH/LH pulse generator activity in mammals.
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Affiliation(s)
- Sho Nakamura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Takuya Sasaki
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Marina Nakanishi
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Koki Yamada
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan
| | - Ai Morishima
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Reika Suzumura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Yuri Kitagawa
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Yasuhiro Morita
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Togo-cho, Aichi, 470-0151, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.
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Nolan PM, Banks G, Bourbia N, Wilcox AG, Bentley L, Moir L, Kent L, Hillier R, Wilson D, Barrett P, Dumbell R. A missense mutation in zinc finger homeobox-3 (ZFHX3) impedes growth and alters metabolism and hypothalamic gene expression in mice. FASEB J 2023; 37:e23189. [PMID: 37713040 PMCID: PMC7615594 DOI: 10.1096/fj.202201829r] [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: 11/07/2022] [Revised: 08/07/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023]
Abstract
A protein altering variant in the gene encoding zinc finger homeobox-3 (ZFHX3) has recently been associated with lower BMI in a human genome-wide association study. We investigated metabolic parameters in mice harboring a missense mutation in Zfhx3 (Zfhx3Sci/+ ) and looked for altered in situ expression of transcripts that are associated with energy balance in the hypothalamus to understand how ZFHX3 may influence growth and metabolic effects. One-year-old male and female Zfhx3Sci/+ mice weighed less, had shorter body length, lower fat mass, smaller mesenteric fat depots, and lower circulating insulin, leptin, and insulin-like growth factor-1 (IGF1) concentrations than Zfhx3+/+ littermates. In a second cohort of 9-20-week-old males and females, Zfhx3Sci/+ mice ate less than wildtype controls, in proportion to body weight. In a third cohort of female-only Zfhx3Sci/+ and Zfhx3+/+ mice that underwent metabolic phenotyping from 6 to 14 weeks old, Zfhx3Sci/+ mice weighed less and had lower lean mass and energy expenditure, but fat mass did not differ. We detected increased expression of somatostatin and decreased expression of growth hormone-releasing hormone and growth hormone-receptor mRNAs in the arcuate nucleus (ARC). Similarly, ARC expression of orexigenic neuropeptide Y was decreased and ventricular ependymal expression of orphan G protein-coupled receptor Gpr50 was decreased. We demonstrate for the first time an energy balance effect of the Zfhx3Sci mutation, likely by altering expression of key ARC neuropeptides to alter growth, food intake, and energy expenditure.
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Affiliation(s)
- Patrick M Nolan
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Gareth Banks
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
- Nottingham Trent University, School of Science and Technology, Nottingham, UK
| | - Nora Bourbia
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Ashleigh G Wilcox
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Liz Bentley
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Lee Moir
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Lee Kent
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Rosie Hillier
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
| | - Dana Wilson
- The Rowett Institute, University of Aberdeen, Aberdeen, UK
| | - Perry Barrett
- The Rowett Institute, University of Aberdeen, Aberdeen, UK
| | - Rebecca Dumbell
- MRC Harwell Institute, Mammalian Genetics Unit and Mary Lyon Centre, Oxfordshire, UK
- Nottingham Trent University, School of Science and Technology, Nottingham, UK
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3
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Dumbell R. An appetite for growth: The role of the hypothalamic - pituitary - growth hormone axis in energy balance. J Neuroendocrinol 2022; 34:e13133. [PMID: 35474620 PMCID: PMC9285760 DOI: 10.1111/jne.13133] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 03/05/2022] [Accepted: 03/22/2022] [Indexed: 11/30/2022]
Abstract
Links between the regulation of growth and energy balance are clear; to fuel growth, there must be consumption of energy. Therefore, it is perhaps intuitive that interactions between the hypothalamic - pituitary - growth hormone axis (growth axis) and pathways that drive metabolic processes exist. Overproduction of growth hormone has been associated with diabetes and metabolic disease for decades and the opposing effects of growth hormone and insulin have been studied since early experiments almost a century ago. The relationship between neuroendocrine axes can be complex and the growth axis is no exception, interacting with energy balance in several organ systems, both in the periphery and centrally in hypothalamic nuclei. Much is known about peripheral interactions between growth axis hormones and processes such as glucose homeostasis and adipogenesis. More is still being learned about the molecular actions of growth axis hormones in adipose and other metabolically active tissues, and recent findings are discussed in this perspective. However, less is known about interactions with central energy balance pathways in the hypothalamus. This perspective aims to summarise what is known about these interactions, taking lessons from human studies and animal genetic and seasonal models, and discusses what this may mean in an evolving landscape of personalised medicine.
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Affiliation(s)
- Rebecca Dumbell
- School of Science and Technology, Department of BiosciencesNottingham Trent UniversityNottinghamUK
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Sheep as a model for neuroendocrinology research. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 189:1-34. [PMID: 35595346 DOI: 10.1016/bs.pmbts.2022.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Animal models remain essential to understand the fundamental mechanisms of physiology and pathology. Particularly, the complex and dynamic nature of neuroendocrine cells of the hypothalamus make them difficult to study. The neuroendocrine systems of the hypothalamus are critical for survival and reproduction, and are highly conserved throughout vertebrate evolution. Their roles in controlling body metabolism, growth and body composition, stress, electrolyte balance, and reproduction, have been intensively studied, and have yielded groundbreaking discoveries. Many of these discoveries would not have been feasible without the use of the domestic sheep (Ovis aries). The sheep has been used for decades to study the neuroendocrine systems of the hypothalamus and has become a model for human neuroendocrinology. The aim of this chapter is to review some of the profound biomedical discoveries made possible by the use of sheep. The advantages and limitations of sheep as a neuroendocrine model will be discussed. While no animal model can perfectly recapitulate a human disease or condition, sheep are invaluable for enabling manipulations not possible in human subjects and isolating physiologic variables to garner insight into neuroendocrinology and associated pathologies.
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Merkley CM, Shuping SL, Nestor CC. Neuronal networks that regulate gonadotropin-releasing hormone/luteinizing hormone secretion during undernutrition: evidence from sheep. Domest Anim Endocrinol 2020; 73:106469. [PMID: 32247618 DOI: 10.1016/j.domaniend.2020.106469] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/26/2020] [Accepted: 02/28/2020] [Indexed: 01/19/2023]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons are the final common conduit from the central nervous system in the reproductive axis, controlling luteinizing hormone (LH) secretion from the gonadotropes of the anterior pituitary. Although it is generally accepted that undernutrition inhibits GnRH/LH secretion, the central mechanisms that underlie the link between energy balance and reproduction remain to be fully elucidated. Sheep have been a longstanding and invaluable animal model for examination of the nutritional regulation of GnRH/LH secretion, given their ability to serve a biomedical and agricultural purpose. In this review, we summarize work that has used the ovine model to examine the central mechanisms whereby undernutrition regulates GnRH/LH secretion. Specifically, we focus our attention to the arcuate nucleus of the hypothalamus and on neurons that express kisspeptin, neurokinin B, dynorphin, proopiomelanocortin, and neuropeptide y/agouti-related peptide (NPY/AgRP). We examine their roles in mediating the effects of leptin and insulin and their effects on LH during undernutrition, as well as their regulation under conditions of undernutrition. This review will also highlight the interactions between the aforementioned neuronal networks themselves, which may be important for our understanding of the roles each play in relaying information regarding energy status during times of undernutrition to ultimately regulate GnRH/LH secretion.
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Affiliation(s)
- C M Merkley
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA
| | - S L Shuping
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA
| | - C C Nestor
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA.
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Coutinho EA, Prescott M, Hessler S, Marshall CJ, Herbison AE, Campbell RE. Activation of a Classic Hunger Circuit Slows Luteinizing Hormone Pulsatility. Neuroendocrinology 2020; 110:671-687. [PMID: 31630145 DOI: 10.1159/000504225] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 10/11/2019] [Indexed: 11/19/2022]
Abstract
INTRODUCTION The central regulation of fertility is carefully coordinated with energy homeostasis, and infertility is frequently the outcome of energy imbalance. Neurons in the hypothalamus expressing neuropeptide Y and agouti-related peptide (NPY/AgRP neurons) are strongly implicated in linking metabolic cues with fertility regulation. OBJECTIVE We aimed here to determine the impact of selectively activating NPY/AgRP neurons, critical regulators of metabolism, on the activity of luteinizing hormone (LH) pulse generation. METHODS We employed a suite of in vivo optogenetic and chemogenetic approaches with serial measurements of LH to determine the impact of selectively activating NPY/AgRP neurons on dynamic LH secretion. In addition, electrophysiological studies in ex vivo brain slices were employed to ascertain the functional impact of activating NPY/AgRP neurons on gonadotropin-releasing hormone (GnRH) neurons. RESULTS Selective activation of NPY/AgRP neurons significantly decreased post-castration LH secretion. This was observed in males and females, as well as in prenatally androgenized females that recapitulate the persistently elevated LH pulse frequency characteristic of polycystic ovary syndrome (PCOS). Reduced LH pulse frequency was also observed when optogenetic stimulation was restricted to NPY/AgRP fiber projections surrounding GnRH neuron cell bodies in the rostral preoptic area. However, electrophysiological studies in ex vivo brain slices indicated these effects were likely to be indirect. CONCLUSIONS These data demonstrate the ability of NPY/AgRP neuronal signaling to modulate and, specifically, reduce GnRH/LH pulse generation. The findings suggest a mechanism by which increased activity of this hunger circuit, in response to negative energy balance, mediates impaired fertility in otherwise reproductively fit states, and highlight a potential mechanism to slow LH pulsatility in female infertility disorders, such as PCOS, that are associated with hyperactive LH secretion.
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Affiliation(s)
- Eulalia A Coutinho
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Melanie Prescott
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Sabine Hessler
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Christopher J Marshall
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Allan E Herbison
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Rebecca E Campbell
- Department of Physiology and Centre for Neuroendocrinology, Otago School of Biomedical Sciences, University of Otago, Dunedin, New Zealand,
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Foradori CD, Whitlock BK, Daniel JA, Zimmerman AD, Jones MA, Read CC, Steele BP, Smith JT, Clarke IJ, Elsasser TH, Keisler DH, Sartin JL. Kisspeptin Stimulates Growth Hormone Release by Utilizing Neuropeptide Y Pathways and Is Dependent on the Presence of Ghrelin in the Ewe. Endocrinology 2017; 158:3526-3539. [PMID: 28977590 DOI: 10.1210/en.2017-00303] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 07/13/2017] [Indexed: 12/31/2022]
Abstract
Although kisspeptin is the primary stimulator of gonadotropin-releasing hormone secretion and therefore the hypothalamic-pituitary-gonadal axis, recent findings suggest kisspeptin can also regulate additional neuroendocrine processes including release of growth hormone (GH). Here we show that central delivery of kisspeptin causes a robust rise in plasma GH in fasted but not fed sheep. Kisspeptin-induced GH secretion was similar in animals fasted for 24 hours and those fasted for 72 hours, suggesting that the factors involved in kisspeptin-induced GH secretion are responsive to loss of food availability and not the result of severe negative energy balance. Pretreatment with the neuropeptide Y (NPY) Y1 receptor antagonist, BIBO 3304, blocked the effects of kisspeptin-induced GH release, implicating NPY as an intermediary. Kisspeptin treatment induced c-Fos in NPY and GH-releasing hormone (GHRH) cells of the arcuate nucleus. The same kisspeptin treatment resulted in a reduction in c-Fos in somatostatin (SS) cells in the periventricular nucleus. Finally, blockade of systemic ghrelin release or antagonism of the ghrelin receptor eliminated or reduced the ability of kisspeptin to induce GH release, suggesting the presence of ghrelin is required for kisspeptin-induced GH release in fasted animals. Our findings support the hypothesis that during short-term fasting, systemic ghrelin concentrations and NPY expression in the arcuate nucleus rise. This permits kisspeptin activation of NPY cells. In turn, NPY stimulates GHRH cells and inhibits SS cells, resulting in GH release. We propose a mechanism by which kisspeptin conveys reproductive and hormone status onto the somatotropic axis, resulting in alterations in GH release.
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Affiliation(s)
- Chad D Foradori
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
| | - Brian K Whitlock
- Department of Large Animal Clinical Sciences, University of Tennessee, Knoxville, Tennessee 37996
| | - Jay A Daniel
- Department of Animal Science, Berry College, Mt. Berry, Georgia 30149
| | - Arthur D Zimmerman
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
| | - Melaney A Jones
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
| | - Casey C Read
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
| | - Barbara P Steele
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
| | - Jeremy T Smith
- School of Anatomy, Physiology and Human Biology, University of Western Australia, Perth, Crawley, Washington 6009, Australia
| | - Iain J Clarke
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria 3800, Australia
| | - Theodore H Elsasser
- Animal Genomics and Improvement Laboratory, US Department of Agriculture, Agricultural Research Service, Beltsville, Maryland 20705
| | - Duane H Keisler
- Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211
| | - James L Sartin
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, Alabama 36849
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Nguyen LT, Reverter A, Cánovas A, Venus B, Islas-Trejo A, Porto-Neto LR, Lehnert SA, Medrano JF, Moore SS, Fortes MRS. Global differential gene expression in the pituitary gland and the ovaries of pre- and postpubertal Brahman heifers. J Anim Sci 2017; 95:599-615. [PMID: 28380590 DOI: 10.2527/jas.2016.0921] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
To understand genes, pathways, and networks related to puberty, we characterized the transcriptome of two tissues: the pituitary gland and ovaries. Samples were harvested from pre- and postpubertal Brahman heifers (same age group). Brahman heifers () are older at puberty compared with , a productivity issue. With RNA sequencing, we identified differentially expressed (DEx) genes and important transcription factors (TF) and predicted coexpression networks. The number of DEx genes detected in the pituitary gland was 284 ( < 0.05), and was the most DEx gene (fold change = 4.12, = 0.01). The gene promotes bone mineralization through transforming growth factor-β (TGFβ) signaling. Further studies of the link between bone mineralization and puberty could target . In ovaries, 3,871 genes were DEx ( < 0.05). Four highly DEx genes were noteworthy for their function: (a γ-aminobutyric acid [GABA] transporter), (), and () and its receptor . These genes had higher ovarian expression in postpubertal heifers. The GABA and its receptors and transporters were expressed in the ovaries of many mammals, suggesting a role for this pathway beyond the brain. The pathway has been known to influence the timing of puberty in rats, via modulation of GnRH. The effects of at the hypothalamus, pituitary gland, and ovaries have been documented. and its receptors are known factors in the release of GnRH, similar to and GABA, although their roles in ovarian tissue are less clear. Pathways previously related to puberty such as TGFβ signaling ( = 6.71 × 10), Wnt signaling ( = 4.1 × 10), and peroxisome proliferator-activated receptor (PPAR) signaling ( = 4.84 × 10) were enriched in our data set. Seven genes were identified as key TF in both tissues: , , , , , , and a novel gene. An ovarian subnetwork created with TF and significant ovarian DEx genes revealed five zinc fingers as regulators: , , , , and . Recent work of hypothalamic gene expression also pointed to zinc fingers as TF for bovine puberty. Although some zinc fingers may be ubiquitously expressed, the identification of DEx genes in common across tissues points to key regulators of puberty. The hypothalamus and pituitary gland had eight DEx genes in common. The hypothalamus and ovaries had 89 DEx genes in common. The pituitary gland and ovaries had 48 DEx genes in common. Our study confirmed the complexity of puberty and suggested further investigation on genes that code zinc fingers.
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Cardoso RC, Alves BRC, Prezotto LD, Thorson JF, Tedeschi LO, Keisler DH, Amstalden M, Williams GL. Reciprocal changes in leptin and NPY during nutritional acceleration of puberty in heifers. J Endocrinol 2014; 223:289-98. [PMID: 25326602 DOI: 10.1530/joe-14-0504] [Citation(s) in RCA: 15] [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] [Indexed: 12/16/2022]
Abstract
Feeding a high-concentrate diet to heifers during the juvenile period, resulting in increased body weight (BW) gain and adiposity, leads to early-onset puberty. In this study, we tested the hypothesis that the increase in GnRH/LH release during nutritional acceleration of puberty is accompanied by reciprocal changes in circulating leptin and central release of neuropeptide Y (NPY). The heifers were weaned at 3.5 months of age and fed to gain either 0.5 (Low-gain; LG) or 1.0 kg/day (High-gain; HG) for 30 weeks. A subgroup of heifers was fitted surgically with third ventricle guide cannulas and was subjected to intensive cerebrospinal fluid (CSF) and blood sampling at 8 and 9 months of age. Mean BW was greater in HG than in LG heifers at week 6 of the experiment and remained greater thereafter. Starting at 9 months of age, the percentage of pubertal HG heifers was greater than that of LG heifers, although a replicate effect was observed. During the 6-h period in which CSF and blood were collected simultaneously, all LH pulses coincided with or shortly followed a GnRH pulse. At 8 months of age, the frequency of LH pulses was greater in the HG than in the LG group. Beginning at 6 months of age, concentrations of leptin were greater in HG than in LG heifers. At 9 months of age, concentrations of NPY in the CSF were lesser in HG heifers. These observations indicate that increased BW gain during juvenile development accelerates puberty in heifers, coincident with reciprocal changes in circulating concentrations of leptin and hypothalamic NPY release.
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Affiliation(s)
- Rodolfo C Cardoso
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Bruna R C Alves
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Ligia D Prezotto
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Jennifer F Thorson
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Luis O Tedeschi
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Duane H Keisler
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Marcel Amstalden
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
| | - Gary L Williams
- Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA Animal Reproduction LaboratoryTexas A&M AgriLife Research Station, 3507 Highway 59E, Beeville, Texas 78102, USADepartment of Animal ScienceKleberg Center, Texas A&M University, College Station, Texas 77843, USADivision of Animal SciencesAnimal Science Research Center, University of Missouri, Columbia, Missouri 65211, USA
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10
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Cardoso RC, Alves BRC, Prezotto LD, Thorson JF, Tedeschi LO, Keisler DH, Park CS, Amstalden M, Williams GL. Use of a stair-step compensatory gain nutritional regimen to program the onset of puberty in beef heifers. J Anim Sci 2014; 92:2942-9. [PMID: 24879767 DOI: 10.2527/jas.2014-7713] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
It was hypothesized that metabolic programming of processes underlying puberty can be shifted temporally through the use of a stair-step compensatory growth model such that puberty is optimally timed to occur at 11 to 12 mo of age. Forty crossbred beef heifers were weaned at approximately 3.5 mo of age and, after a 2-wk acclimation period, were assigned randomly to 1 of 4 nutritional groups: 1) low control (LC), restricted feed intake of a forage-based diet to promote BW gain of 0.5 kg/d until 14 mo of age, 2) high control (HC), controlled feed intake of a high-concentrate diet to promote BW gain of 1 kg/d until 14 mo of age, 3) stair-step 1 (SS-1), ad libitum feed intake of a high-concentrate diet until 6.5 mo of age followed by restricted access to a high-forage diet to promote BW gain of 0.35 kg/d until 9 mo of age, ad libitum feed intake of a high-concentrate diet until 11.5 mo of age, and restricted intake of a high-forage diet to promote BW gain of 0.35 kg/d until 14 mo of age, and 4) stair-step 2 (SS-2), reverse sequence of SS-1, beginning with restricted access to a high-forage diet. Body weight (every 2 wk) and circulating concentrations of leptin (monthly) were determined throughout the experiment. Concentrations of progesterone in blood samples collected twice weekly beginning at 8 mo of age were used to determine pubertal status. Body weight gain followed a pattern similar to that proposed in our experimental design. Circulating concentrations of leptin increased following distinct elevations in BW but decreased abruptly after feed intake restriction. Survival analysis indicated that the percentage of pubertal heifers in the LC group was lower (P < 0.05) than all other groups throughout the experiment. Although heifers in SS-1 were nutritionally restricted between 6.5 and 9 mo of age, the proportion pubertal by 12 mo of age did not differ (P = 0.36) from that of the HC group, with 80% and 70% pubertal in SS-1 and HC, respectively. In contrast, the proportion of heifers pubertal by 12 mo of age in the SS-2 group (40%) was lower (P < 0.05) than both HC and SS-1. However, by 14 mo of age, 90% of heifers in the SS-2 group had also attained puberty compared to only 40% of the LC group. In summary, these data provide evidence that changes in the nutritional and metabolic status during the early juvenile period can program the onset of puberty that occurs months later, allowing optimal timing of sexual maturation in replacement beef heifers.
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Affiliation(s)
- R C Cardoso
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843
| | - B R C Alves
- Department of Animal Science, Texas A&M University, College Station 77843
| | - L D Prezotto
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843
| | - J F Thorson
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843
| | - L O Tedeschi
- Department of Animal Science, Texas A&M University, College Station 77843
| | - D H Keisler
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - C S Park
- Department of Animal Sciences, North Dakota State University, Fargo 58108
| | - M Amstalden
- Department of Animal Science, Texas A&M University, College Station 77843
| | - G L Williams
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville 78102 Department of Animal Science, Texas A&M University, College Station 77843
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11
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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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12
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Abstract
Appetite control is a major issue in normal growth and in suboptimal growth performance settings. A number of hormones, in particular leptin, activate or inhibit orexigenic or anorexigenic neurotransmitters within the arcuate nucleus of the hypothalamus, where feed intake regulation is integrated. Examples of appetite regulatory neurotransmitters are the stimulatory neurotransmitters neuropeptide Y (NPY), agouti-related protein (AgRP), orexin and melanin-concentrating hormone and the inhibitory neurotransmitter, melanocyte-stimulating hormone (MSH). Examination of messenger RNA (using in situ hybridization and real-time PCR) and proteins (using immunohistochemistry) for these neurotransmitters in ruminants has indicated that physiological regulation occurs in response to fasting for several of these critical genes and proteins, especially AgRP and NPY. Moreover, intracerebroventricular injection of each of the four stimulatory neurotransmitters can increase feed intake in sheep and may also regulate either growth hormone, luteinizing hormone, cortisol or other hormones. In contrast, both leptin and MSH are inhibitory to feed intake in ruminants. Interestingly, the natural melanocortin-4 receptor (MC4R) antagonist, AgRP, as well as NPY can prevent the inhibition of feed intake after injection of endotoxin (to model disease suppression of appetite). Thus, knowledge of the mechanisms regulating feed intake in the hypothalamus may lead to mechanisms to increase feed intake in normal growing animals and prevent the wasting effects of severe disease in animals.
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13
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Allen CC, Alves BRC, Li X, Tedeschi LO, Zhou H, Paschal JC, Riggs PK, Braga-Neto UM, Keisler DH, Williams GL, Amstalden M. Gene expression in the arcuate nucleus of heifers is affected by controlled intake of high- and low-concentrate diets1. J Anim Sci 2012; 90:2222-32. [DOI: 10.2527/jas.2011-4684] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- C. C. Allen
- Animal Reproduction Laboratory, Texas AgriLife Research, Beeville 78102
- Departments of Animal Science, Texas A&M University, College Station 77843
| | - B. R. C. Alves
- Departments of Animal Science, Texas A&M University, College Station 77843
| | - X. Li
- Poultry Science, and Texas A&M University, College Station 77843
| | - L. O. Tedeschi
- Departments of Animal Science, Texas A&M University, College Station 77843
| | - H. Zhou
- Poultry Science, and Texas A&M University, College Station 77843
| | - J. C. Paschal
- Texas AgriLife Extension, Texas AgriLife Research and Extension Center, Corpus Christi 78406
| | - P. K. Riggs
- Departments of Animal Science, Texas A&M University, College Station 77843
| | - U. M. Braga-Neto
- Electrical and Computer Engineering, Texas A&M University, College Station 77843
| | - D. H. Keisler
- Division of Animal Sciences, University of Missouri, Columbia 65211
| | - G. L. Williams
- Animal Reproduction Laboratory, Texas AgriLife Research, Beeville 78102
- Departments of Animal Science, Texas A&M University, College Station 77843
| | - M. Amstalden
- Departments of Animal Science, Texas A&M University, College Station 77843
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14
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Hausman GJ, Barb CR, Lents CA. Leptin and reproductive function. Biochimie 2012; 94:2075-81. [PMID: 22980196 DOI: 10.1016/j.biochi.2012.02.022] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 02/17/2012] [Indexed: 12/15/2022]
Abstract
Adipose tissue plays a dynamic role in whole-body energy homeostasis by acting as an endocrine organ. Collective evidence indicates a strong link between neural influences and adipocyte expression and secretion of leptin. Developmental changes in these relationships are considered important for pubertal transition in reproductive function. Leptin augments secretion of gonadotropin hormones, which are essential for initiation and maintenance of normal reproductive function, by acting centrally at the hypothalamus to regulate gonadotropin-releasing hormone (GnRH) neuronal activity and secretion. The effects of leptin on GnRH are mediated through interneuronal pathways involving neuropeptide-Y, proopiomelanocortin and kisspeptin. Increased infertility associated with diet induced obesity or central leptin resistance are likely mediated through the kisspeptin-GnRH pathway. Furthermore, Leptin regulates reproductive function by altering the sensitivity of the pituitary gland to GnRH and acting at the ovary to regulate follicular and luteal steroidogenesis. Thus leptin serves as a putative signal that links metabolic status with the reproductive axis. The intent of this review is to examine the biological role of leptin with energy metabolism, and reproduction.
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Affiliation(s)
- Gary J Hausman
- USDA, ARS, Richard B. Russell Research Center, RRC, 950 College Station Rd, Athens, GA 30605, USA.
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15
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Functional characterisation of the bovine neuropeptide Y gene promoter and evaluation of the transcriptional activities of promoter haplotypes. Mol Biol Rep 2011; 39:919-28. [PMID: 21562764 DOI: 10.1007/s11033-011-0817-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 05/03/2011] [Indexed: 12/11/2022]
Abstract
Neuropeptide Y (NPY) is a potent orexigenic agent. The molecular mechanisms underlying the regulation of bovine NPY gene expression by its promoter region is currently unknown. The objectives of this research were to: (i) identify the SNPs in the promoter region of the bovine NPY gene, (ii) investigate the effects of these SNPs by measuring promoter transcriptional activities of different bovine NPY promoter haplotypes and; (iii) identify the minimal promoter region (MPR) required for basal activity of the NPY gene in vitro. Seventeen SNPs were identified in the promoter region. Of these, 14 affected putative transcription factors binding motifs including a TATA binding protein factor at -20, GC-Box factors SP1 at -170 and GATA binding motifs at -120 and -347. The SNPs were assigned to five major haplotypes (BtNPY_H1-5), of which BtNPY_H5 had maximum transcriptional activity. The region extending to -134 nt was identified as the MPR. This MPR was confirmed by the identification of a putative TATA box (-29 nt) and two SP1/GC binding sites (-94 and -118 nt), within this region. However, promoter expression was significantly enhanced when the construct contained the -614 to -1019 nt region. In conclusion, a number of SNPs characterised in the bovine NPY promoter especially those affecting the transcription factor binding sites, enhancer and repressor regions have the potential to affect NPY gene expression. Natural variation exists in the promoter region of the bovine NPY gene, which should be further explored for selection of energetic efficiency in cattle.
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16
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Miller DW, Bennett EJ, Harrison JL, Findlay PA, Adam CL. Adiposity and plane of nutrition influence reproductive neuroendocrine and appetite responses to intracerebroventricular insulin and neuropeptide-Y in sheep. Reprod Fertil Dev 2011; 23:329-38. [PMID: 21211466 DOI: 10.1071/rd10150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 07/28/2010] [Indexed: 01/18/2023] Open
Abstract
Long-term nutritional background is thought to influence hypothalamic appetite and reproductive neuroendocrine responses to short-term nutritional feedback. In order to investigate this phenomenon, the effects of intracerebroventricular administration of insulin or neuropeptide-Y (NPY) on LH secretion and voluntary food intake (VFI) were examined in sheep that were initially thin and kept on an increasing nutritional plane (INP), or initially fat and kept on a decreasing nutritional plane (DNP), for 10 weeks. Intracerebroventricular insulin stimulated LH secretion and suppressed VFI in INP sheep when initially thin, but not when they became fat, and had no effect on LH in DNP sheep when initially fat, and stimulated LH secretion when they became thin. Intracerebroventricular NPY had no effect on LH or VFI in INP sheep when initially thin, decreased LH secretion and increased VFI when they became fat, and decreased LH secretion in DNP sheep when initially fat but had no effect when they became thin. Therefore, sensitivity to insulin increases with low or decreasing nutritional status and decreases with high or increasing nutritional status, whereas sensitivity to NPY increases with high or increasing nutritional status and decreases with low or decreasing nutritional status. In conclusion, reproductive neuroendocrine and appetite responses to acute changes in nutritional feedback signals depend on the individual's longer-term nutritional background.
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Affiliation(s)
- D W Miller
- School of Veterinary and Biomedical Sciences, Murdoch University, South Street, Murdoch, WA 6150, Australia.
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17
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Amstalden M, Alves BRC, Liu S, Cardoso RC, Williams GL. Neuroendocrine pathways mediating nutritional acceleration of puberty: insights from ruminant models. Front Endocrinol (Lausanne) 2011; 2:109. [PMID: 22654842 PMCID: PMC3356117 DOI: 10.3389/fendo.2011.00109] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Accepted: 12/09/2011] [Indexed: 01/15/2023] Open
Abstract
The pubertal process is characterized by an activation of physiological events within the hypothalamic-adenohypophyseal-gonadal axis which culminate in reproductive competence. Excessive weight gain and adiposity during the juvenile period is associated with accelerated onset of puberty in females. The mechanisms and pathways by which excess energy balance advances puberty are unclear, but appear to involve an early escape from estradiol negative feedback and early initiation of high-frequency episodic gonadotropin-releasing hormone (GnRH) secretion. Hypothalamic neurons, particularly neuropeptide Y and proopiomelanocortin neurons are likely important components of the pathway sensing and transmitting metabolic information to the control of GnRH secretion. Kisspeptin neurons may also have a role as effector neurons integrating metabolic and gonadal steroid feedback effects on GnRH secretion at the time of puberty. Recent studies indicate that leptin-responsive neurons within the ventral premammillary nucleus play a critical role in pubertal progression and challenge the relevance of kisspeptin neurons in this process. Nevertheless, the nutritional control of puberty is likely to involve an integration of major sensor and effector pathways that interact with modulatory circuitries for a fine control of GnRH neuron function. In this review, observations made in ruminant species are emphasized for a comparative perspective.
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Affiliation(s)
- Marcel Amstalden
- Department of Animal Science, Texas A&M UniversityCollege Station, TX, USA
- *Correspondence: Marcel Amstalden, Department of Animal Science, Texas A&M University, 2471 TAMU, College Station, TX 77845-2471, USA. e-mail:
| | - Bruna R. C. Alves
- Department of Animal Science, Texas A&M UniversityCollege Station, TX, USA
| | - Songrui Liu
- Department of Animal Science, Texas A&M UniversityCollege Station, TX, USA
| | - Rodolfo C. Cardoso
- Department of Animal Science, Texas A&M UniversityCollege Station, TX, USA
- Animal Reproduction Laboratory, Texas AgriLife ResearchBeeville, TX, USA
| | - Gary L. Williams
- Department of Animal Science, Texas A&M UniversityCollege Station, TX, USA
- Animal Reproduction Laboratory, Texas AgriLife ResearchBeeville, TX, USA
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18
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Tillet Y, Picard S, Bruneau G, Ciofi P, Wańkowska M, Wójcik-Gładysz A, Polkowska J. Hypothalamic arcuate neuropeptide Y-neurons decrease periventricular somatostatin-neuronal activity before puberty in the female lamb: Morphological arguments. J Chem Neuroanat 2010; 40:265-71. [DOI: 10.1016/j.jchemneu.2010.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 07/08/2010] [Accepted: 07/08/2010] [Indexed: 11/26/2022]
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19
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Gahete MD, Durán-Prado M, Luque RM, Martínez-Fuentes AJ, Quintero A, Gutiérrez-Pascual E, Córdoba-Chacón J, Malagón MM, Gracia-Navarro F, Castaño JP. Understanding the multifactorial control of growth hormone release by somatotropes: lessons from comparative endocrinology. Ann N Y Acad Sci 2009; 1163:137-53. [PMID: 19456335 DOI: 10.1111/j.1749-6632.2008.03660.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Control of postnatal growth is the main, but not the only, role for growth hormone (GH) as this hormone also contributes to regulating metabolism, reproduction, immunity, development, and osmoregulation in different species. Likely owing to this variety of group-specific functions, GH production is differentially regulated across vertebrates, with an apparent evolutionary trend to simplification, especially in the number of stimulatory factors governing substantially GH release. Thus, teleosts exhibit a multifactorial regulation of GH secretion, with a number of factors, from the newly discovered fish GH-releasing hormone (GHRH) to pituitary adenylate cyclase-activating peptide (PACAP) but also gonadotropin-releasing hormone, dopamine, corticotropin-releasing hormone, and somatostatin(s) directly controlling somatotropes. In amphibians and reptiles, GH secretion is primarily stimulated by the major hypothalamic peptides GHRH and PACAP and inhibited by somatostatin(s), while other factors (ghrelin, thyrotropin-releasing hormone) also influence GH release. Finally, in birds and mammals, primary control of GH secretion is exerted by a dual interplay between GHRH and somatostatin. In addition, somatotrope function is modulated by additional hypothalamic and peripheral factors (e.g., ghrelin, leptin, insulin-like growth factor-I), which together enable a balanced integration of feedback signals related to processes in which GH plays a relevant regulatory role, such as metabolic and energy status, reproductive, and immune function. Interestingly, in contrast to the high number of stimulatory factors impinging upon somatotropes, somatostatin(s) stand(s) as the main primary inhibitory regulator(s) for this cell type.
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Affiliation(s)
- Manuel D Gahete
- Department of Cell Biology, Physiology and Immunology, University of Córdoba, Cordoba, Spain
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20
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Leptin signaling in brain: A link between nutrition and cognition? Biochim Biophys Acta Mol Basis Dis 2008; 1792:401-8. [PMID: 19130879 DOI: 10.1016/j.bbadis.2008.12.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Revised: 12/05/2008] [Accepted: 12/07/2008] [Indexed: 12/22/2022]
Abstract
Leptin is a protein hormone that acts within the hypothalamus to suppress food intake and decrease body adiposity, but it is increasingly clear that the hypothalamus is not the only site of leptin action, nor food intake the only biological effect of leptin. Instead, leptin is a pleiotropic hormone that impinges on many brain areas, and in doing so alters food intake, motivation, learning, memory, cognitive function, neuroprotection, reproduction, growth, metabolism, energy expenditure, and more. This diversity of function also means that a dysregulation of leptin secretion and signaling can have far reaching effects. To date research on leptin signaling has focused primarily on the hypothalamus, and the result is a relative lack of information regarding the impact of leptin signaling and leptin resistance in non-hypothalamic areas, despite a growing literature implicating leptin in the regulation of neuronal structure and function in the hippocampus, cortex and other brain areas associated with cognition.
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21
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Ogasawara H, Aso H, Nagai Y, Matsumoto K, Okamura H, Tanaka S, Watanabe K, Ohwada S, Yamaguchi T. Presence of neuropeptide Y in somatotrophs of cattle. Domest Anim Endocrinol 2008; 35:274-80. [PMID: 18678462 DOI: 10.1016/j.domaniend.2008.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Revised: 06/10/2008] [Accepted: 06/11/2008] [Indexed: 10/21/2022]
Abstract
Neuropeptide Y (NPY), a 36-amino acid member of the pancreatic polypeptide family, was found to be present by immunohistochemistry in the bovine adenohypophysis. NPY mRNA expression was confirmed in the adenohypophysis by RT-PCR. NPY immunoreactivity was present in about 38% of adenohypophyseal cells in the pars distalis. However, NPY immunoreactive cells (NPY-ir cells) were scarce in the zona tuberalis. Immunohistochemistry of NPY and specific hormones using mirror sections revealed that NPY was colocalized in GH immunoreactive cells. Over 90% of somatotrophs corresponded to NPY-ir cells. These results indicate that endogenous NPY is present in the bovine somatotroph and may act as an endocrine intercellular mediator in the adenohypophysis.
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Affiliation(s)
- Hideki Ogasawara
- Laboratory of Functional Morphology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan
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22
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Gasser CL, Bridges GA, Mussard ML, Grum DE, Kinder JE, Day ML. Induction of precocious puberty in heifers III: Hastened reduction of estradiol negative feedback on secretion of luteinizing hormone1. J Anim Sci 2006; 84:2050-6. [PMID: 16864864 DOI: 10.2527/jas.2005-638] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Precocious puberty (<300 d of age) can be induced in beef heifers by early weaning and feeding a high-concentrate diet. The objective of this experiment was to determine whether precocious puberty occurs as a result of a hastened reduction of estradiol negative feedback on secretion of LH. Thirty crossbred Angus and Simmental heifers were weaned at 83 +/- 2 d of age and 114 +/- 3 kg of BW, blocked by BW, and randomly assigned to receive a high-concentrate (60% corn; H) or control (30% corn; C) diet and to receive ovariectomy (OVX), OVX plus an estradiol implant (OVXE), or to remain intact (INT). Residual ovarian tissue after OVX necessitated withdrawal of 6 heifers during the course of the experiment, resulting in the following treatment groups: OVX-C, n = 3; OVX-H, n = 5; OVXE-C, n = 4; OVXE-H, n = 2; INT-C, n = 5; INT-H, n = 5. To determine concentrations of progesterone and estradiol, blood samples were collected weekly beginning at a mean age of 160 d. To characterize LH concentrations, serial blood samples were collected at 12-min intervals for 12 h at mean ages of 119, 149, 188, 217, 246, 281, 323, 365, 407, and 449 d. By a mean age of 202 d, heifers fed the H diet were heavier (P < 0.05) than those fed the C diet. Heifers in the INT-H treatment attained puberty earlier (P < 0.05) than in the INT-C treatment (275 +/- 30 vs. 385 +/- 14 d of age, respectively). Overall mean concentrations of estradiol did not differ between OVXE-H and OVXE-C, between INT-H and INT-C, or between OVXE and INT treatments. The OVX treatments exhibited greater LH pulse frequency than the OVXE and INT treatments by the first serial blood collection (treatment x age, P < 0.05). The frequency of LH pulses was greater (P < 0.05) in the INT-H than the INT-C treatment by a mean age of 246 d and was greater (P < 0.05) in the OVXE-H than the OVXE-C treatment by a mean age of 281 d. In the OVXE-H treatment, LH secretion increased and subsequently "escaped" from estradiol negative feedback (detection of > or = 1 LH pulse/h) earlier (P < 0.05) than in the OVXE-C treatment (307 +/- 30 and 420 +/- 21 d of age, respectively). It is concluded that advancing the reduction of estradiol negative feedback on secretion of LH is the mechanism by which early weaning and feeding a high-concentrate diet results in precocious puberty in heifers.
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Affiliation(s)
- C L Gasser
- Department of Animal Sciences, The Ohio State University, Columbus 43210, USA
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23
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Barb CR, Kraeling RR, Rampacek GB, Hausman GJ. The role of neuropeptide Y and interaction with leptin in regulating feed intake and luteinizing hormone and growth hormone secretion in the pig. Reproduction 2006; 131:1127-35. [PMID: 16735552 DOI: 10.1530/rep.1.01108] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two experiments (EXP) were conducted in ovariectomized prepubertal gilts to test the hypothesis that neuropeptide Y (NPY) stimulates appetite and modulates LH and GH secretion, and that leptin modifies such acute effects of NPY on feeding behavior and LH and GH secretion. In EXP I, gilts received intracerebroventricular (ICV) injections of 0.9% saline (saline; n=6), or 10 μg (n=7), 50 μg (n=5) or 100 μg (n=7) NPY in saline and blood samples were collected. In EXP II, gilts received ICV injections of S (n=4), or 50 μg leptin (n=4), or 100 μg NPY (n=4) or 100 μg NPY +50 μg leptin (n=4) in saline, and feed intake was measured at 4, 20 and 44 h after feed presentation and blood samples collected. In EXP I, NPY suppressed LH secretion and the 100 μg dose stimulated GH secretion. In EXP II, NPY reversed the inhibitory effect of leptin on feed intake and suppressed LH secretion, but serum GH concentrations were unaffected. These results support the hypothesis that NPY modulates feed intake, and LH and GH secretion and may serve as a neural link between metabolic state and the reproductive and growth axis in the pig.
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Affiliation(s)
- C Richard Barb
- USDA/ARS, Animal Physiology Research Unit, Russell Research Center, Athens, GA 30604-5677, USA
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24
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Iqbal J, Manley TR, Ciofi P, Clarke IJ. Reduction in adiposity affects the extent of afferent projections to growth hormone-releasing hormone and somatostatin neurons and the degree of colocalization of neuropeptides in growth hormone-releasing hormone and somatostatin cells of the ovine hypothalamus. Endocrinology 2005; 146:4776-85. [PMID: 16081637 DOI: 10.1210/en.2005-0622] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Various neuropeptides and neurotransmitters affect GH secretion by acting on GHRH and somatostatin (SRIF) cells. GH secretion is also affected by alteration in adiposity, which could be via modulation of GHRH and SRIF cells. We quantified colocalization of neuropeptides in GHRH and SRIF cells and afferent projections to these cells in lean (food restricted) and normally fed sheep (n=4/group). The number of GHRH-immunoreactive (IR) cells in the arcuate nucleus was higher in lean animals, but the number of SRIF-IR cells in the periventricular nucleus was similar in the two groups. A subpopulation of GHRH-IR cells colocalized neuropeptide Y in lean animals, but this was not seen in normally fed animals. GHRH/galanin (GAL) colocalization was higher in lean animals with no difference in numbers of GHRH/tyrosine hydroxylase or GHRH/GAL-like peptide cells. SRIF/enkephalin colocalization was lower in lean animals. The percentage of GHRH neurons receiving SRIF input was similar in lean and normally fed animals, but more GHRH cells received input from enkephalin afferents in normally fed animals. The percentage of SRIF cells receiving GHRH, neuropeptide Y, GAL, and orexin afferents was higher in lean animals. These findings provide an anatomical evidence of central mechanism(s) by which appetite-regulating peptides and dopamine could regulate GH secretion. Increased input to SRIF cells in lean animals may be inhibitory and permissive of increased GH. The appearance of NPY in GHRH cells of lean animals may be a mechanism for regulation of increasing GH secretion with reduced adiposity.
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Affiliation(s)
- Javed Iqbal
- Prince Henry's Institute of Medical Research, Victoria, Australia
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25
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Zieba DA, Amstalden M, Williams GL. Regulatory roles of leptin in reproduction and metabolism: a comparative review. Domest Anim Endocrinol 2005; 29:166-85. [PMID: 15927772 DOI: 10.1016/j.domaniend.2005.02.019] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 02/10/2005] [Accepted: 02/19/2005] [Indexed: 11/30/2022]
Abstract
Leptin plays an important role in signaling nutritional status to the central reproductive axis of mammals and appears to be at least a permissive factor in the initiation of puberty. The expression and secretion of leptin are correlated with body fat mass and are acutely affected by changes in feed intake. Moreover, circulating leptin increases during pubertal development in rodents, human females and heifers. Effects of leptin are mediated mainly via receptor activation of the JAK-STAT pathway; however, activation of alternative pathways, such as MAP kinase, has also been reported. Although the leptin receptor (LR) has not been found on GnRH neurons, leptin stimulates the release of GnRH from rat and porcine hypothalamic explants. Moreover, leptin increases the release of LH in rats and from adenohypophyseal explants and/or cells from full-fed rats and pigs. In contrast, stimulation of the hypothalamic-gonadotropic axis by leptin in cattle and sheep is observed predominantly in animals and tissues pre-exposed to profound negative energy balance. For example, leptin prevents fasting-mediated reductions in the frequency of LH pulses in peripubertal heifers, augments the magnitude of LH and GnRH pulses in fasted cows, and enhances basal secretion of LH in vivo and from adenohypophyseal explants of fasted cows. However, leptin is incapable of accelerating the frequency of LH pulses in prepubertal heifers, regardless of nutrient status, and has no effect on the secretion of GnRH and LH in full-fed cattle or hypothalamic/hypophyseal explants derived thereof. Similar to results obtained with LH, basal secretion of GH from anterior pituitary explants of fasted, but not normal-fed cows, was potentiated acutely by low, but not high, doses of leptin. Mechanisms through which undernutrition hypersensitize the hypothalamic-gonadotropic axis to leptin may involve up-regulation of the LR. However, an increase in LR mRNA expression is not a requisite feature of heightened adenohypophyseal responses in fasted cattle. To date, leptin has not been successful for inducing puberty in ruminants. Future therapeutic uses for recombinant leptin that exploit states of nutritional hypersensitization, and identification of genetic markers for genotypic variation in leptin resistance, are currently under investigation.
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Affiliation(s)
- D A Zieba
- Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, 3507 Hwy 59E, Beeville, TX 78102, USA
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Abstract
The recently discovered protein, leptin, which is secreted by fat cells, has been implicated in regulation of feed intake or energy balance and the neuroendocrine axis in rodents, humans and large domestic animals. Leptin was first identified as the gene product found to be deficient in the obese (ob/ob) mouse. Administration of leptin to ob/ob mice restored reproduction as well as reducing feed intake and causing weight loss. The leptin receptor (LR) which has been cloned and is a member of the class 1 cytokine family of receptors, is found in the brain and pituitary of all species studied to date. Neuropeptide Y has been proposed as the primary mediator of leptin action in the hypothalamus to regulate luteinizing hormone (LH) and growth hormone (GH) secretion. In vitro studies using both hypothalamic explants and pituitary cell culture provided evidence that supports a direct action of leptin at the level of brain and pituitary gland in the pig, but only the pituitary in cattle. Central administration of leptin increased LH secretion in the fasted cow and ewe, but not in control fed animals, indicating that metabolic state is an important factor in modulating the hypothalamic-pituitary response to leptin. Changing serum leptin concentrations and leptin mRNA expression were associated with onset of puberty in heifers and gilts. Thus, leptin appears to be an important link between metabolic status and the neuroendocrine axis.
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Affiliation(s)
- C R Barb
- USDA-ARS, Animal Physiology Research Unit, Russell Research Center, P.O. Box 5677, Athens, GA 30604-5677, USA.
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Garcia MR, Amstalden M, Keisler DH, Raver N, Gertler A, Williams GL. Leptin attenuates the acute effects of centrally administered neuropeptide Y on somatotropin but not gonadotropin secretion in ovariectomized cows. Domest Anim Endocrinol 2004; 26:189-200. [PMID: 15036374 DOI: 10.1016/j.domaniend.2003.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2003] [Accepted: 10/01/2003] [Indexed: 11/27/2022]
Abstract
We tested the hypothesis that recombinant ovine leptin would attenuate the acute effects of neuropeptide Y (NPY) on secretion of GH and gonadotropins (LH and FSH) in cows. Ovariectomized cows (n=6) fitted with third ventricle guide cannulas were assigned randomly to each of three groups in a Latin square arrangement: (1) control; saline treatment only, (2) NPY; saline followed by NPY, and (3) L-NPY; leptin pretreatment followed by NPY. Treatments were: s.c. injection of saline or leptin (30 microg/kg BW) at time 0, i.v. injection of saline or leptin (30 microg/kg BW) at 70 min, and intracerebroventricular (i.c.v.) injection of saline or NPY (500 microg) at 90 min. Plasma leptin was elevated (P<0.01) at least four-fold throughout the experiment in the L-NPY group. Mean plasma concentrations of LH declined within 1 h and were lower (P<0.03) than controls in both the NPY and L-NPY groups beginning 2 h after NPY injection. An acute increase in plasma concentrations of GH was observed within 1 h after NPY in the NPY group and mean values were greater (P<0.01) than controls. However, in the L-NPY group, leptin pretreatment attenuated the NPY effect on GH. Treatments had no effect on FSH secretion. Results confirm suppressive and stimulatory effects of NPY on LH and GH secretion, respectively, and indicate that leptin can attenuate the acute effects of NPY on GH secretion in cattle.
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Affiliation(s)
- M R Garcia
- Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Hwy 59E, Beeville, TX 78102-9410, USA
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Dobbins A, Lubbers LS, Jackson GL, Kuehl DE, Hileman SM. Neuropeptide Y gene expression in male sheep: influence of photoperiod and testosterone. Neuroendocrinology 2004; 79:82-9. [PMID: 15004430 DOI: 10.1159/000076631] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Accepted: 12/15/2003] [Indexed: 11/19/2022]
Abstract
The frequency of pulsatile release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) is high in the breeding season and low in the nonbreeding season. These alterations in the patterns of GnRH and LH release are due to an interaction of daylength and gonadal steroid negative feedback. A vast amount of data indicates that steroid-responsive neural systems may play a role in regulating seasonal changes in GnRH release. One candidate system is neuropeptide Y (NPY). To determine the independent and interactive influences of photoperiod and steroid exposure on NPY mRNA levels, we used hypothalamic tissue from four groups (n = 4 per group) of castrated male sheep that were simultaneously housed in photochambers and exposed to: (1) a 16L:8D photoperiod (LD); (2) LD and implanted with testosterone (LD + T); (3) a 10L:14D photoperiod (SD), and (4) SD + T. Circulating levels of T averaged 2.8 +/- 0.2 ng/ml in implanted animals, but were undetectable in nonimplanted males. Mean LH levels were significantly reduced (p < 0.01) in the LD + T group as compared with the other groups which did not differ from each other. The silver grain area per NPY neuron in the arcuate nucleus, as assessed by in situ hybridization, was inversely related to mean LH values, with the grain area per cell being significantly greater (p < 0.05) for LD + T males than for all other groups which did not differ from each other. NPY cell numbers were not significantly different (p > 0.10) among the treatment groups. These results show that NPY mRNA expression is increased in male sheep during a LD photoperiod in a T-dependent manner. Our data are consistent with the idea that NPY is involved in the seasonal regulation of GnRH and LH release in the male sheep.
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Affiliation(s)
- Adam Dobbins
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
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Henry BA. Links between the appetite regulating systems and the neuroendocrine hypothalamus: lessons from the sheep. J Neuroendocrinol 2003; 15:697-709. [PMID: 12787054 DOI: 10.1046/j.1365-2826.2003.01049.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The hypothalamus is integral to the regulation of energy homeostasis and the secretion of hormones from the pituitary gland. Consequently, hypothalamic systems may have a dual purpose in regulating both neuroendocrine function and appetite. To date, most studies investigating the interface between appetite and hormone secretion have been performed in rats or mice that have been acutely fasted or baring a genetic abnormality causing either obesity or aphagia. By contrast, various physiological models, including chronic food-restriction or photoperiodically driven changes in voluntary food intake, add further perspective to the issue. In this regard, sheep provide an innovative model whereby long-term changes in body weight or extended feeding rhythms can be investigated. This review compares and contrasts data obtained in different species with regard to the neuroendocrinology of appetite, and discusses the benefits and knowledge gained from using various nonrodent models with a particular emphasis on a ruminant species.
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Affiliation(s)
- B A Henry
- University Research Centre for Neuroendocrinology, University of Bristol, Bristol, UK.
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