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Almasi N, Zengin HY, Koç N, Uçakturk SA, İskender Mazman D, Heidarzadeh Rad N, Fisunoglu M. Leptin, ghrelin, nesfatin-1, and orexin-A plasma levels in girls with premature thelarche. J Endocrinol Invest 2022; 45:2097-2103. [PMID: 35764868 DOI: 10.1007/s40618-022-01841-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/10/2022] [Indexed: 11/27/2022]
Abstract
PURPOSE Reducing the mean age of puberty onset in recent years has crucial public health, clinical, and social implications. This study aimed to evaluate the serum levels of appetite-related peptides (leptin, ghrelin, nesfatin-1, and orexin-A) and anthropometric data in girls with premature thelarche (PT). METHODS We enrolled 44 girls aged 4-8 years diagnosed with PT and 33 age-matched healthy girls as controls. The demographic data of the girls were obtained using a questionnaire. Anthropometric data were measured and fasting blood samples were collected. RESULTS Body weight, height, body mass index (BMI), body fat mass, and basal metabolic rate (BMR) were higher in the PT group than in the control group (p < 0.05). Serum leptin (p < 0.001), nesfatin-1 (p = 0.001), and orxein-A (p < 0.001) levels were significantly higher in the PT group than in healthy controls. However, there were no significant differences in the serum ghrelin levels between the groups (p > 0.05). The results of multivariate logistic regression revealed that serum leptin level (OR (95% CI): 42.0 (10.91, 173.06), p < 0.001), orexin-A (OR (95% CI): 1.14 (1.04, 1.24), p = 0.006), and BMI for age z-score (OR (95% CI): 6.97 (1.47, 33.4), p = 0.014) elevated the risk of incidence of PT at 4-8 girls. CONCLUSION These results suggest that in addition to serum leptin levels, serum orexin-A and nesaftin-1 can take part in the initiation of PT. Few studies have investigated the relationship between nesfatin-1 and orexin-A levels and age at onset of puberty; hence, it should be a subject for future studies.
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Affiliation(s)
- N Almasi
- Department of Nutrition and Dietetics, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - H Y Zengin
- Department of Biostatistics, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - N Koç
- Department of Child Endocrinology, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - S A Uçakturk
- Department of Child Endocrinology, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - D İskender Mazman
- Department of Child Pediatric, Ministry of Health Ankara City Hospital, Ankara, Turkey
| | - N Heidarzadeh Rad
- Department of Nutrition and Dietetics, Hacettepe University Faculty of Health Sciences, Ankara, Turkey
| | - M Fisunoglu
- Department of Nutrition and Dietetics, Hacettepe University Faculty of Health Sciences, Ankara, Turkey.
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Abdelmissih S. A Bitter Experience That Enlightens the Future: COVID-19 Neurological Affection and Perspectives on the Orexigenic System. Cureus 2022; 14:e30788. [DOI: 10.7759/cureus.30788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
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3
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Mlyczyńska E, Kieżun M, Kurowska P, Dawid M, Pich K, Respekta N, Daudon M, Rytelewska E, Dobrzyń K, Kamińska B, Kamiński T, Smolińska N, Dupont J, Rak A. New Aspects of Corpus Luteum Regulation in Physiological and Pathological Conditions: Involvement of Adipokines and Neuropeptides. Cells 2022; 11:957. [PMID: 35326408 PMCID: PMC8946127 DOI: 10.3390/cells11060957] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 11/17/2022] Open
Abstract
The corpus luteum is a small gland of great importance because its proper functioning determines not only the appropriate course of the estrous/menstrual cycle and embryo implantation, but also the subsequent maintenance of pregnancy. Among the well-known regulators of luteal tissue functions, increasing attention is focused on the role of neuropeptides and adipose tissue hormones-adipokines. Growing evidence points to the expression of these factors in the corpus luteum of women and different animal species, and their involvement in corpus luteum formation, endocrine function, angiogenesis, cells proliferation, apoptosis, and finally, regression. In the present review, we summarize the current knowledge about the expression and role of adipokines, such as adiponectin, leptin, apelin, vaspin, visfatin, chemerin, and neuropeptides like ghrelin, orexins, kisspeptin, and phoenixin in the physiological regulation of the corpus luteum function, as well as their potential involvement in pathologies affecting the luteal cells that disrupt the estrous cycle.
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Affiliation(s)
- Ewa Mlyczyńska
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
| | - Marta Kieżun
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland; (M.K.); (E.R.); (B.K.); (T.K.); (N.S.)
| | - Patrycja Kurowska
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
| | - Monika Dawid
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
| | - Karolina Pich
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
| | - Natalia Respekta
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
| | - Mathilde Daudon
- Unité Physiologie de la Reproduction et des Comportements, French National Institute for Agriculture, Food, and Environment, 37380 Nouzilly, France; (M.D.); (J.D.)
| | - Edyta Rytelewska
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland; (M.K.); (E.R.); (B.K.); (T.K.); (N.S.)
| | - Kamil Dobrzyń
- Department of Zoology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland;
| | - Barbara Kamińska
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland; (M.K.); (E.R.); (B.K.); (T.K.); (N.S.)
| | - Tadeusz Kamiński
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland; (M.K.); (E.R.); (B.K.); (T.K.); (N.S.)
| | - Nina Smolińska
- Department of Animal Anatomy and Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, 10-719 Olsztyn, Poland; (M.K.); (E.R.); (B.K.); (T.K.); (N.S.)
| | - Joelle Dupont
- Unité Physiologie de la Reproduction et des Comportements, French National Institute for Agriculture, Food, and Environment, 37380 Nouzilly, France; (M.D.); (J.D.)
| | - Agnieszka Rak
- Laboratory of Physiology and Toxicology of Reproduction, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, 30-387 Krakow, Poland; (E.M.); (P.K.); (M.D.); (K.P.); (N.R.)
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4
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Azeez IA, Igado OO, Olopade JO. An overview of the orexinergic system in different animal species. Metab Brain Dis 2021; 36:1419-1444. [PMID: 34224065 DOI: 10.1007/s11011-021-00761-0] [Citation(s) in RCA: 10] [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: 10/14/2020] [Accepted: 06/06/2021] [Indexed: 01/13/2023]
Abstract
Orexin (hypocretin), is a neuropeptide produced by a subset of neurons in the lateral hypothalamus. From the lateral hypothalamus, the orexin-containing neurons project their fibres extensively to other brain structures, and the spinal cord constituting the central orexinergic system. Generally, the term ''orexinergic system'' usually refers to the orexin peptides and their receptors, as well as to the orexin neurons and their projections to different parts of the central nervous system. The extensive networks of orexin axonal fibres and their terminals allow these neuropeptidergic neurons to exert great influence on their target regions. The hypothalamic neurons containing the orexin neuropeptides have been implicated in diverse functions, especially related to the control of a variety of homeostatic functions including feeding behaviour, arousal, wakefulness stability and energy expenditure. The broad range of functions regulated by the orexinergic system has led to its description as ''physiological integrator''. In the last two decades, the orexinergic system has been a topic of great interest to the scientific community with many reports in the public domain. From the documentations, variations exist in the neuroanatomical profile of the orexinergic neuron soma, fibres and their receptors from animal to animal. Hence, this review highlights the distinct variabilities in the morphophysiological aspects of the orexinergic system in the vertebrate animals, mammals and non-mammals, its presence in other brain-related structures, including its involvement in ageing and neurodegenerative diseases. The presence of the neuropeptide in the cerebrospinal fluid and peripheral tissues, as well as its alteration in different animal models and conditions are also reviewed.
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Affiliation(s)
- Idris A Azeez
- Department of Veterinary Anatomy, University of Jos, Jos, Nigeria
| | - Olumayowa O Igado
- Department of Veterinary Anatomy, University of Ibadan, Ibadan, Nigeria
| | - James O Olopade
- Department of Veterinary Anatomy, University of Ibadan, Ibadan, Nigeria.
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5
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Williams VM, Bhagwandin A, Swiegers J, Bertelsen MF, Hård T, Thannickal TC, Siegel JM, Sherwood CC, Manger PR. Nuclear organization of orexinergic neurons in the hypothalamus of a lar gibbon and a chimpanzee. Anat Rec (Hoboken) 2021; 305:1459-1475. [PMID: 34535040 DOI: 10.1002/ar.24775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 07/06/2021] [Accepted: 08/17/2021] [Indexed: 11/06/2022]
Abstract
Employing orexin-A immunohistochemical staining we describe the nuclear parcellation of orexinergic neurons in the hypothalami of a lar gibbon and a chimpanzee. The clustering of orexinergic neurons within the hypothalamus and the terminal networks follow the patterns generally observed in other mammals, including laboratory rodents, strepsirrhine primates and humans. The orexinergic neurons were found within three distinct clusters in the ape hypothalamus, which include the main cluster, zona incerta cluster and optic tract cluster. In addition, the orexinergic neurons of the optic tract cluster appear to extend to a more rostral and medial location than observed in other species, being observed in the tuberal region in the anterior ventromedial aspect of the hypothalamus. While orexinergic terminal networks were observed throughout the brain, high density terminal networks were observed within the hypothalamus, medial and intralaminar nuclei of the dorsal thalamus, and within the serotonergic and noradrenergic regions of the midbrain and pons, which is typical for mammals. The expanded distribution of orexinergic neurons into the tuberal region of the ape hypothalamus, is a feature that needs to be investigated in other primate species, but appears to correlate with orexin gene expression in the same region of the human hypothalamus, but these neurons are not revealed with immunohistochemical staining in humans. Thus, it appears that apes have a broader distribution of orexinergic neurons compared to other primate species, but that the neurons within this extension of the optic tract cluster in humans, while expressing the orexin gene, do not produce the neuropeptide.
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Affiliation(s)
- Victoria M Williams
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa.,Division of Clinical Anatomy and Biological Anthropology, Department of Human Biology, University of Cape Town, Cape Town, South Africa
| | - Jordan Swiegers
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
| | - Mads F Bertelsen
- Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark
| | | | - Thomas C Thannickal
- Department of Psychiatry, School of Medicine, and Brain Research Institute, University of California, Los Angeles, Los Angeles, California, USA.,Brain Research Institute, Neurobiology Research, Sepulveda VA Medical Center, Los Angeles, California, USA
| | - Jerome M Siegel
- Department of Psychiatry, School of Medicine, and Brain Research Institute, University of California, Los Angeles, Los Angeles, California, USA.,Brain Research Institute, Neurobiology Research, Sepulveda VA Medical Center, Los Angeles, California, USA
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, District of Columbia, USA
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa
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6
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Malungo IB, Gravett N, Bhagwandin A, Davimes JG, Manger PR. A Preliminary Description of the Sleep-Related Neural Systems in the Brain of the Blue Wildebeest, Connochaetes taurinus. Anat Rec (Hoboken) 2019; 303:1977-1997. [PMID: 31513360 DOI: 10.1002/ar.24265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 06/12/2019] [Accepted: 07/16/2019] [Indexed: 12/18/2022]
Abstract
The current study provides a detailed qualitative description of the organization of the cholinergic, catecholaminergic, serotonergic, orexinergic, and GABAergic sleep-related systems in the brain of the blue wildebeest (Connocheates taurinus), along with a quantitative analysis of the pontine cholinergic and noradrenergic neurons, and the hypothalamic orexinergic neurons. The aim of this study was to compare the nuclear organization of these systems to other mammalian species and specifically that reported for other Cetartiodactyla. In the brain of the blue wildebeest, from the basal forebrain to the pons, the nuclear organization of the cholinergic, catecholaminergic, serotonergic, and orexinergic systems, for the most part, showed a corresponding nuclear organization to that reported in other mammals and more specifically the Cetartiodactyla. Furthermore, the description and distribution of the GABAergic system, which was examined through immunostaining for the calcium binding proteins calbindin, calretinin, and parvalbumin, was also similar to that seen in other mammals. These findings indicate that sleep in the blue wildebeest is likely to show typically mammalian features in terms of the global brain activity of the generally recognized sleep states of mammals, but Cetartiodactyl-specific features of the orexinergic system may act to lower overall daily total sleep time in relation to similar sized non-Cetartiodactyl mammals. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1977-1997, 2020. © 2019 American Association for Anatomy.
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Affiliation(s)
- Illke B Malungo
- School of Anatomical Sciences, Faulty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nadine Gravett
- School of Anatomical Sciences, Faulty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faulty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Joshua G Davimes
- School of Anatomical Sciences, Faulty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Paul R Manger
- School of Anatomical Sciences, Faulty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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7
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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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8
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Targeting the orexinergic system: Mainly but not only for sleep-wakefulness therapies. ALEXANDRIA JOURNAL OF MEDICINE 2019. [DOI: 10.1016/j.ajme.2014.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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9
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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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10
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Grafe LA, Bhatnagar S. The contribution of orexins to sex differences in the stress response. Brain Res 2018; 1731:145893. [PMID: 30081036 DOI: 10.1016/j.brainres.2018.07.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/22/2018] [Accepted: 07/12/2018] [Indexed: 02/07/2023]
Abstract
Women are twice as likely as men to suffer from stress-related psychiatric disorders, such as post-traumatic stress disorder (PTSD) and Major Depressive Disorder (MDD), however, the biological basis of these sex differences is not fully understood. Interestingly, orexins are known to be dysregulated in these disorders. This review first discusses the important role of orexins regulating the response to stress. Next, we review the evidence for sex differences in the orexin system, in which the majority of both preclinical and clinical studies have reported higher orexin system expression in females. Finally, we discuss the functional consequences of these sex differences in orexin expression. Most importantly, the preclinical literature reveals that higher orexin system activity in females contributes to exaggerated neuroendocrine and behavioral responses to stress. In sum, the available data suggests that orexins may be important in the etiology of stress-related psychiatric disorders that present differently in men and women. Thus, targeting orexins could potentially ameliorate many phenotypes of stress-related illness in a sex-specific way.
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Affiliation(s)
- Laura A Grafe
- Department of Anesthesiology and Critical Care, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Seema Bhatnagar
- Department of Anesthesiology and Critical Care, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; The University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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11
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Affiliation(s)
- Olaf Jöhren
- Center of Brain, Behavior and Metabolism (CBBM), University of Lübeck, Ratzeburger Allee 160, 23562, Lübeck, Germany.
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12
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Kirsz K, Szczęsna M, Borsuk A, Zięba DA. Cross-talk between leptin, ghrelin and orexins in the central nervous system of seasonal animals – a review. ANNALS OF ANIMAL SCIENCE 2017. [DOI: 10.1515/aoas-2016-0070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The maintenance of energy homeostasis is achieved with ‘detectors’ that receive signals from the external and internal environment and with multidirectional ‘communication routes’ including neuronal networks and body fluids, such as blood and cerebrospinal fluid. Changes in the energy demands of organisms are caused by current physiological status and environmental conditions, including season and food availability. Little is known about the interactions between the metabolic indicators involved in the maintenance of energy homeostasis, e.g., leptin, orexins and ghrelin. Sheep and other seasonal animals are highly adaptable to their environments because of the plasticity of their neural and endocrine systems. Sheep exhibit leptin resistance and are thus an extremely interesting model for research on the relationship between hormonal indicators of energy metabolism. The paper is focused mainly on the anatomical and functional communication between leptin, ghrelin and orexins, which play principal roles in the adaptation of energetic demands to environmental fluctuations.
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Affiliation(s)
- Katarzyna Kirsz
- Department of Animal Biotechnology, Laboratory of Biotechnology and Genomics, Agricultural University of Krakow, Rędzina 1B, 30-248 Kraków, Poland
| | - Małgorzata Szczęsna
- Department of Animal Biotechnology, Laboratory of Biotechnology and Genomics, Agricultural University of Krakow, Rędzina 1B, 30-248 Kraków, Poland
| | - Anna Borsuk
- Department of Animal Biotechnology, Laboratory of Biotechnology and Genomics, Agricultural University of Krakow, Rędzina 1B, 30-248 Kraków, Poland
| | - Dorota A. Zięba
- Department of Animal Biotechnology, Laboratory of Biotechnology and Genomics, Agricultural University of Krakow, Rędzina 1B, 30-248 Kraków, Poland
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Davimes JG, Alagaili AN, Bennett NC, Mohammed OB, Bhagwandin A, Manger PR, Gravett N. Neurochemical organization and morphology of the sleep related nuclei in the brain of the Arabian oryx, Oryx leucoryx. J Chem Neuroanat 2017; 81:53-70. [PMID: 28163217 DOI: 10.1016/j.jchemneu.2017.02.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/30/2017] [Accepted: 02/01/2017] [Indexed: 12/01/2022]
Abstract
The Arabian oryx, Oryx leucoryx, is a member of the superorder Cetartiodactyla and is native to the Arabian Desert. The desert environment can be considered extreme in which to sleep, as the ranges of temperatures experienced are beyond what most mammals encounter. The current study describes the nuclear organization and neuronal morphology of the systems that have been implicated in sleep control in other mammals for the Arabian oryx. The nuclei delineated include those revealed immunohistochemically as belonging to the cholinergic, catecholaminergic, serotonergic and orexinergic systems within the basal forebrain, hypothalamus, midbrain and pons. In addition, we examined the GABAergic neurons and their terminal networks surrounding or within these nuclei. The majority of the neuronal systems examined followed the typical mammalian organizational plan, but some differences were observed: (1) the neuronal morphology of the cholinergic laterodorsal tegmental (LDT) and pedunculopontine tegmental (PPT) nuclei, as well as the parvocellular subdivision of the orexinergic main cluster, exhibited Cetartiodactyl-specific features; (2) the dorsal division of the catecholaminergic anterior hypothalamic group (A15d), which has not been reported in any member of the Artiodactyla studied to date, was present in the brain of the Arabian oryx; and (3) the catecholaminergic tuberal cell group (A12) was notably more expansive than previously seen in any other mammal. The A12 nucleus has been associated functionally to osmoregulation in other mammals, and thus its expansion could potentially be a species specific feature of the Arabian oryx given their native desert environment and the need for extreme water conservation.
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Affiliation(s)
- Joshua G Davimes
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa
| | - Abdulaziz N Alagaili
- KSU Mammals Research Chair, Department of Zoology, King Saud University, Riyadh 11451, Saudi Arabia
| | - Nigel C Bennett
- SARChI Chair for Mammalian Behavioural Ecology and Physiology, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Osama B Mohammed
- KSU Mammals Research Chair, Department of Zoology, King Saud University, Riyadh 11451, Saudi Arabia
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa
| | - Nadine Gravett
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, Johannesburg, South Africa.
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14
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Zhao Y, Singh C, Prober DA, Wayne NL. Morphological and Physiological Interactions Between GnRH3 and Hypocretin/Orexin Neuronal Systems in Zebrafish (Danio rerio). Endocrinology 2016; 157:4012-4020. [PMID: 27533887 PMCID: PMC5045510 DOI: 10.1210/en.2016-1381] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/11/2016] [Indexed: 01/11/2023]
Abstract
GnRH neurons integrate internal and external cues to control sexual maturation and fertility. Homeostasis of energy balance and food intake correlates strongly with the status of reproduction. Neuropeptides secreted by the hypothalamus involved in modulating energy balance and feeding may play additional roles in the regulation of reproduction. Hypocretin (Hcrt) (also known as orexin) is one such peptide, primarily controlling sleep/wakefulness, food intake, and reward processing. There is a growing body of evidence indicating that Hcrt/orexin (Hcrt) modulates reproduction through interacting with the hypothalamo-pituitary-gonadal axis in mammals. To explore potential morphological and functional interactions between the GnRH and Hcrt neuronal systems, we employed a variety of experimental approaches including confocal imaging, immunohistochemistry, and electrophysiology in transgenic zebrafish, in which fluorescent proteins are genetically expressed in GnRH3 and Hcrt neurons. Our imaging data revealed close apposition and direct connection between GnRH3 and Hcrt neuronal systems in the hypothalamus during larval development through adulthood. Furthermore, the Hcrt receptor (HcrtR) is expressed in GnRH3 neurons. Electrophysiological data revealed a reversible inhibitory effect of Hcrt on GnRH3 neuron electrical activity, which was blocked by the HcrtR antagonist almorexant. In addition, Hcrt had no effect on the electrical activity of GnRH3 neurons in the HcrtR null mutant zebrafish (HcrtR-/-). Our findings demonstrate a close anatomical and functional relationship between Hcrt and GnRH neuronal systems in zebrafish. It is the first demonstration of a link between neuronal circuits controlling sleeping/arousal/feeding and reproduction in zebrafish, an important animal model for investigating the molecular genetics of development.
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Affiliation(s)
- Yali Zhao
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - Chanpreet Singh
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - David A Prober
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - Nancy L Wayne
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
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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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Dell LA, Spocter MA, Patzke N, Karlson KÆ, Alagaili AN, Bennett NC, Muhammed OB, Bertelsen MF, Siegel JM, Manger PR. Orexinergic bouton density is lower in the cerebral cortex of cetaceans compared to artiodactyls. J Chem Neuroanat 2015; 68:61-76. [DOI: 10.1016/j.jchemneu.2015.07.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 06/29/2015] [Accepted: 07/22/2015] [Indexed: 12/25/2022]
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Skrapits K, Kanti V, Savanyú Z, Maurnyi C, Szenci O, Horváth A, Borsay BÁ, Herczeg L, Liposits Z, Hrabovszky E. Lateral hypothalamic orexin and melanin-concentrating hormone neurons provide direct input to gonadotropin-releasing hormone neurons in the human. Front Cell Neurosci 2015; 9:348. [PMID: 26388735 PMCID: PMC4559643 DOI: 10.3389/fncel.2015.00348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 08/20/2015] [Indexed: 12/03/2022] Open
Abstract
Hypophysiotropic projections of gonadotropin-releasing hormone (GnRH)-synthesizing neurons form the final common output way of the hypothalamus in the neuroendocrine control of reproduction. Several peptidergic neuronal systems of the medial hypothalamus innervate human GnRH cells and mediate crucially important hormonal and metabolic signals to the reproductive axis, whereas much less is known about the contribution of the lateral hypothalamic area to the afferent control of human GnRH neurons. Orexin (ORX)- and melanin-concentrating hormone (MCH)-synthesizing neurons of this region have been implicated in diverse behavioral and autonomic processes, including sleep and wakefulness, feeding and other functions. In the present immunohistochemical study, we addressed the anatomical connectivity of these neurons to human GnRH cells in post-mortem hypothalamic samples obtained from autopsies. We found that 38.9 ± 10.3% and 17.7 ± 3.3% of GnRH-immunoreactive (IR) perikarya in the infundibular nucleus of human male subjects received ORX-IR and MCH-IR contacts, respectively. On average, each 1 mm segment of GnRH dendrites received 7.3 ± 1.1 ORX-IR and 3.7 ± 0.5 MCH-IR axo-dendritic appositions. Overall, the axo-dendritic contacts dominated over the axo-somatic contacts and represented 80.5 ± 6.4% of ORX-IR and 76.7 ± 4.6% of MCH-IR inputs to GnRH cells. Based on functional evidence from studies of laboratory animals, the direct axo-somatic and axo-dendritic input from ORX and MCH neurons to the human GnRH neuronal system may convey critical metabolic and other homeostatic signals to the reproducive axis. In this study, we also report the generation and characterization of new antibodies for immunohistochemical detection of GnRH neurons in histological sections.
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Affiliation(s)
- Katalin Skrapits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Vivien Kanti
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Zsófia Savanyú
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Csilla Maurnyi
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Ottó Szenci
- Department and Clinic for Production Animals, Faculty of Veterinary Science, Szent István University Üllő, Hungary ; MTA-SZIE Large Animal Clinical Research Group, Dóra major Üllő, Hungary
| | - András Horváth
- Department and Clinic for Production Animals, Faculty of Veterinary Science, Szent István University Üllő, Hungary
| | - Beáta Á Borsay
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen Debrecen, Hungary
| | - László Herczeg
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen Debrecen, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary ; Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
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Clarke IJ. Interface between metabolic balance and reproduction in ruminants: focus on the hypothalamus and pituitary. Horm Behav 2014; 66:15-40. [PMID: 24568750 DOI: 10.1016/j.yhbeh.2014.02.005] [Citation(s) in RCA: 38] [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] [Received: 10/02/2013] [Revised: 02/13/2014] [Accepted: 02/15/2014] [Indexed: 01/24/2023]
Abstract
This article is part of a Special Issue "Energy Balance". The interface between metabolic regulators and the reproductive system is reviewed with special reference to the sheep. Even though sheep are ruminants with particular metabolic characteristics, there is a broad consensus across species in the way that the reproductive system is influenced by metabolic state. An update on the neuroendocrinology of reproduction indicates the need to account for the way that kisspeptin provides major drive to gonadotropin releasing hormone (GnRH) neurons and also mediates the feedback effects of gonadal steroids. The way that kisspeptin function is influenced by appetite regulating peptides (ARP) is considered. Another newly recognised factor is gonadotropin inhibitory hormone (GnIH), which has a dual function in that it suppresses reproductive function whilst also acting as an orexigen. Our understanding of the regulation of food intake and energy expenditure has expanded exponentially in the last 3 decades and historical perspective is provided. The function of the regulatory factors and the hypothalamic cellular systems involved is reviewed with special reference to the sheep. Less is known of these systems in the cow, especially the dairy cow, in which a major fertility issue has emerged in parallel with selection for increased milk production. Other endocrine systems--the hypothalamo-pituitary-adrenal axis, the growth hormone (GH) axis and the thyroid hormones--are influenced by metabolic state and are relevant to the interface between metabolic function and reproduction. Special consideration is given to issues such as season and lactation, where the relationship between metabolic hormones and reproductive function is altered.
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Affiliation(s)
- Iain J Clarke
- Monash University, Department of Physiology, Wellington Road, Clayton 3168, Australia.
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Orexin A and B in vitro modify orexins receptors expression and gonadotropins secretion of anterior pituitary cells of proestrous rats. ACTA ACUST UNITED AC 2013; 188:25-30. [PMID: 24333629 DOI: 10.1016/j.regpep.2013.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 11/27/2013] [Accepted: 12/04/2013] [Indexed: 11/22/2022]
Abstract
AIM Orexin A and orexin B (hypocretins) are neuropeptides synthesized mainly by neurons located in the lateral hypothalamus and projections throughout the brain. They are agonists at both the orexin 1 and orexin 2G protein-coupled receptors. They have been related to arousal, sleep and feeding, autonomic and neuroendocrine functions. Their role in the brain control of gonadotropins secretion was postulated in rodents and humans. Previously, we demonstrated the participation of the orexinergic system in attaining successful reproduction in in vivo studies. METHODS We studied in vitro the effects of both neuropeptides, in the presence or absence of selective antagonists, on the mRNA expression of orexin 1 and orexin 2 receptors in anterior pituitary cells of proestrous rats, as well as the direct effects on FSH and LH secretion. RESULTS Both orexin A and orexin B increased FSH and LH secretion; these effects were suppressed by the orexin 1 receptor blocking agent SB-334867 and the orexin 2 receptor antagonists JNJ-10397049. Orexin A and orexin B decreased OX1 receptor mRNA expression and this effect was modified only when both blocking agents were present. Neither orexin A nor the blocking drugs by themselves modified OX2 receptor mRNA expression. Orexin B treatment increased the mRNA expression of OX2 receptor. The effect was abolished only by the OX2 receptor antagonist. CONCLUSION In an in vitro model, we demonstrated a direct effect of orexins on gonadotropins release and orexins receptors expression, underlining the hypothesis that orexins participate in the brain control of pituitary functions.
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Cellular location and major terminal networks of the orexinergic system in the brain of two megachiropterans. J Chem Neuroanat 2013; 53:64-71. [DOI: 10.1016/j.jchemneu.2013.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/05/2013] [Accepted: 09/05/2013] [Indexed: 11/19/2022]
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Hrabovszky E, Liposits Z. Afferent neuronal control of type-I gonadotropin releasing hormone neurons in the human. Front Endocrinol (Lausanne) 2013; 4:130. [PMID: 24062728 PMCID: PMC3778916 DOI: 10.3389/fendo.2013.00130] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/03/2013] [Indexed: 12/30/2022] Open
Abstract
Understanding the regulation of the human menstrual cycle represents an important ultimate challenge of reproductive neuroendocrine research. However, direct translation of information from laboratory animal experiments to the human is often complicated by strikingly different and unique reproductive strategies and central regulatory mechanisms that can be present in even closely related animal species. In all mammals studied so far, type-I gonadotropin releasing hormone (GnRH) synthesizing neurons form the final common output way from the hypothalamus in the neuroendocrine control of the adenohypophysis. Under various physiological and pathological conditions, hormonal and metabolic signals either regulate GnRH neurons directly or act on upstream neuronal circuitries to influence the pattern of pulsatile GnRH secretion into the hypophysial portal circulation. Neuronal afferents to GnRH cells convey important metabolic-, stress-, sex steroid-, lactational-, and circadian signals to the reproductive axis, among other effects. This article gives an overview of the available neuroanatomical literature that described the afferent regulation of human GnRH neurons by peptidergic, monoaminergic, and amino acidergic neuronal systems. Recent studies of human genetics provided evidence that central peptidergic signaling by kisspeptins and neurokinin B (NKB) play particularly important roles in puberty onset and later, in the sex steroid-dependent feedback regulation of GnRH neurons. This review article places special emphasis on the topographic distribution, sexual dimorphism, aging-dependent neuroanatomical changes, and plastic connectivity to GnRH neurons of the critically important human hypothalamic kisspeptin and NKB systems.
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Affiliation(s)
- Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 43 Szigony Street, Budapest 1083, Hungary e-mail:
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
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22
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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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23
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Clarke IJ, Caraty A. Kisspeptin and seasonality of reproduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 784:411-30. [PMID: 23550017 DOI: 10.1007/978-1-4614-6199-9_19] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Wild and domesticated species display seasonality in reproductive function, controlled predominantly by photoperiod. Seasonal alterations in breeding status are caused by changes in the secretion of gonadotropin-releasing hormone (GnRH) that are mediated by upstream neuronal afferents that regulate the GnRH cells. In particular, kisspeptin appears to play a major role in seasonality of reproduction, transducing the feedback effect of gonadal steroids as well as having an independent (nonsteroid dependent) circannual rhythm. A substantial body of data on this issue has been obtained from studies in sheep and hamsters and this is reviewed here in detail. Kisspeptin function is upregulated during the breeding season in sheep, stimulating reproductive function, but contradictory data are found in Siberian and Syrian hamsters. The relative quiescence of kisspeptin cells in the nonbreeding season can be counteracted by administration of the peptide, leading to activation of reproductive function. Although there is a major role for melatonin in the transduction of photoperiod to the reproductive system, kisspeptin cells do not appear to express the melatonin receptor, so the means by which seasonality changes the level of kisspeptin activity remains unknown.
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Affiliation(s)
- Iain J Clarke
- Department of Physiology, Monash University, Australia.
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24
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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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25
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Garcia-Garcia RM. Integrative control of energy balance and reproduction in females. ISRN VETERINARY SCIENCE 2012; 2012:121389. [PMID: 23762577 PMCID: PMC3671732 DOI: 10.5402/2012/121389] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 09/04/2012] [Indexed: 11/23/2022]
Abstract
There is a strong association between nutrition and reproduction. Chronic dietary energy deficits as well as energy surpluses can impair reproductive capacity. Metabolic status impacts reproductive function at systemic level, modulating the hypothalamic GnRH neuronal network and/or the pituitary gonadotropin secretion through several hormones and neuropeptides, and at the ovarian level, acting through the regulation of follicle growth and steroidogenesis by means of the growth hormone-IGF-insulin system and local ovarian mediators. In the past years, several hormones and neuropeptides have been emerging as important mediators between energy balance and reproduction. The present review goes over the main sites implicated in the control of energy balance linked to reproductive success and summarizes the most important metabolic and neuroendocrine signals that participate in reproductive events with special emphasis on the role of recently discovered neuroendocrine peptides. Also, a little overview about the effects of maternal nutrition, affecting offspring reproduction, has been presented.
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Affiliation(s)
- R M Garcia-Garcia
- Physiology Department (Animal Physiology), Complutense University, Avenida Puerta de Hierro S/N, 28040 Madrid, Spain
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26
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Dell LA, Patzke N, Bhagwandin A, Bux F, Fuxe K, Barber G, Siegel JM, Manger PR. Organization and number of orexinergic neurons in the hypothalamus of two species of Cetartiodactyla: a comparison of giraffe (Giraffa camelopardalis) and harbour porpoise (Phocoena phocoena). J Chem Neuroanat 2012; 44:98-109. [PMID: 22683547 PMCID: PMC3551539 DOI: 10.1016/j.jchemneu.2012.06.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 06/01/2012] [Accepted: 06/01/2012] [Indexed: 11/18/2022]
Abstract
The present study describes the organization of the orexinergic (hypocretinergic) neurons in the hypothalamus of the giraffe and harbour porpoise--two members of the mammalian Order Cetartiodactyla which is comprised of the even-toed ungulates and the cetaceans as they share a monophyletic ancestry. Diencephalons from two sub-adult male giraffes and two adult male harbour porpoises were coronally sectioned and immunohistochemically stained for orexin-A. The staining revealed that the orexinergic neurons could be readily divided into two distinct neuronal types based on somal volume, area and length, these being the parvocellular and magnocellular orexin-A immunopositive (OxA+) groups. The magnocellular group could be further subdivided, on topological grounds, into three distinct clusters--a main cluster in the perifornical and lateral hypothalamus, a cluster associated with the zona incerta and a cluster associated with the optic tract. The parvocellular neurons were found in the medial hypothalamus, but could not be subdivided, rather they form a topologically amorphous cluster. The parvocellular cluster appears to be unique to the Cetartiodactyla as these neurons have not been described in other mammals to date, while the magnocellular nuclei appear to be homologous to similar nuclei described in other mammals. The overall size of both the parvocellular and magnocellular neurons (based on somal volume, area and length) were larger in the giraffe than the harbour porpoise, but the harbour porpoise had a higher number of both parvocellular and magnocellular orexinergic neurons than the giraffe despite both having a similar brain mass. The higher number of both parvocellular and magnocellular orexinergic neurons in the harbour porpoise may relate to the unusual sleep mechanisms in the cetaceans.
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Affiliation(s)
- Leigh-Anne Dell
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa
| | - Nina Patzke
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa
- Department of Psychiatry, University of California, Los Angeles, Neurobiology Research 151A3, Sepulveda VAMC, 16111 Plummer St, North Hills, CA 91343, USA
| | - Faiza Bux
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa
| | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet, Retzius väg 8, S-171 77 Stockholm, Sweden
| | - Grace Barber
- Department of Psychiatry, University of California, Los Angeles, Neurobiology Research 151A3, Sepulveda VAMC, 16111 Plummer St, North Hills, CA 91343, USA
| | - Jerome M. Siegel
- Department of Psychiatry, University of California, Los Angeles, Neurobiology Research 151A3, Sepulveda VAMC, 16111 Plummer St, North Hills, CA 91343, USA
| | - Paul R. Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown 2193, Johannesburg, South Africa
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27
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Abstract
The orexin peptides and their two receptors are involved in multiple physiological processes, including energy homeostasis, arousal, stress and reward. Higher signaling of the orexin peptides at the orexin receptors (OXR) protects against obesity, but it is less clear how their activation in different brain regions contributes to this behavioral output. This review summarizes the evidence available for a role of central OXR in energy homeostasis and their contribution to obesity. A detailed analysis of anatomical, cellular and behavioral evidence shows that modulation of energy homeostasis by the OXR is largely dependent upon anatomical and cellular context. It also shows that obesity resistance provided by activation of the OXR is distributed across multiple brain sites with site-specific actions. We suggest that understanding the role of the OXR in the development of obesity requires considering both specific mechanisms within brain regions and interactions of orexinergic input between multiple sites.
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28
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Nishiguchi R, Azuma M, Yokobori E, Uchiyama M, Matsuda K. Gonadotropin-releasing hormone 2 suppresses food intake in the zebrafish, Danio rerio. Front Endocrinol (Lausanne) 2012; 3:122. [PMID: 23087673 PMCID: PMC3473230 DOI: 10.3389/fendo.2012.00122] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 09/30/2012] [Indexed: 12/14/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is an evolutionarily conserved neuropeptide with 10 amino acid residues, of which several structural variants exist. A molecular form known as GnRH2 ([His(5) Trp(7) Tyr(8)]GnRH, also known as chicken GnRH II) is widely distributed in vertebrates except for rodents, and has recently been implicated in the regulation of feeding behavior in goldfish. However, the influence of GnRH2 on feeding behavior in other fish has not yet been studied. In the present study, therefore, we investigated the role of GnRH2 in the regulation of feeding behavior in a zebrafish model, and examined its involvement in food intake after intracerebroventricular (ICV) administration. ICV injection of GnRH2 at 0.1 and 1 pmol/g body weight (BW) induced a marked decrease of food consumption in a dose-dependent manner during 30 min after feeding. Cumulative food intake was significantly decreased by ICV injection of GnRH2 at 1 pmol/g BW during the 30-min post-treatment observation period. The anorexigenic action of GnRH2 was completely blocked by treatment with the GnRH type I receptor antagonist Antide at 25 pmol/g BW. We also examined the effect of feeding condition on the expression level of the GnRH2 transcript in the hypothalamus. Levels of GnRH2 mRNA obtained from fish that had been provided excess food for 7 days were higher than those in fish that had been fed normally. These results suggest that, in zebrafish, GnRH2 acts as an anorexigenic factor, as is the case in goldfish.
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Affiliation(s)
- Ryo Nishiguchi
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of ToyamaToyama, Japan
| | - Morio Azuma
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of ToyamaToyama, Japan
| | - Eri Yokobori
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of ToyamaToyama, Japan
| | - Minoru Uchiyama
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of ToyamaToyama, Japan
| | - Kouhei Matsuda
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of ToyamaToyama, Japan
- Laboratory of Regulatory Biology, Graduate School of Innovative Life Science, University of ToyamaToyama, Japan
- *Correspondence: Kouhei Matsuda, Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan. e-mail:
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Nixon JP, Kotz CM, Novak CM, Billington CJ, Teske JA. Neuropeptides controlling energy balance: orexins and neuromedins. Handb Exp Pharmacol 2012:77-109. [PMID: 22249811 DOI: 10.1007/978-3-642-24716-3_4] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In this chapter, we review the feeding and energy expenditure effects of orexin (also known as hypocretin) and neuromedin. Orexins are multifunctional neuropeptides that affect energy balance by participating in regulation of appetite, arousal, and spontaneous physical activity. Central orexin signaling for all functions originates in the lateral hypothalamus-perifornical area and is likely functionally differentiated based on site of action and on interacting neural influences. The effect of orexin on feeding is likely related to arousal in some ways but is nonetheless a separate neural process that depends on interactions with other feeding-related neuropeptides. In a pattern distinct from other neuropeptides, orexin stimulates both feeding and energy expenditure. Orexin increases in energy expenditure are mainly by increasing spontaneous physical activity, and this energy expenditure effect is more potent than the effect on feeding. Global orexin manipulations, such as in transgenic models, produce energy balance changes consistent with a dominant energy expenditure effect of orexin. Neuromedins are gut-brain peptides that reduce appetite. There are gut sources of neuromedin, but likely the key appetite-related neuromedin-producing neurons are in the hypothalamus and parallel other key anorectic neuropeptide expression in the arcuate to paraventricular hypothalamic projection. As with other hypothalamic feeding-related peptides, hindbrain sites are likely also important sources and targets of neuromedin anorectic action. Neuromedin increases physical activity in addition to reducing appetite, thus producing a consistent negative energy balance effect. Together with the other various neuropeptides, neurotransmitters, neuromodulators, and neurohormones, neuromedin and orexin act in the appetite network to produce changes in food intake and energy expenditure, which ultimately influences the regulation of body weight.
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Affiliation(s)
- Joshua P Nixon
- Veterans Affairs Medical Center, Research Service (151), Minneapolis, MN, USA
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Orexinergic innervation of the extended amygdala and basal ganglia in the rat. Brain Struct Funct 2011; 217:233-56. [DOI: 10.1007/s00429-011-0343-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 08/16/2011] [Indexed: 10/17/2022]
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31
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Control of GnRH secretion: one step back. Front Neuroendocrinol 2011; 32:367-75. [PMID: 21216259 DOI: 10.1016/j.yfrne.2011.01.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 11/17/2010] [Accepted: 01/03/2011] [Indexed: 01/09/2023]
Abstract
The reproductive system is controlled by gonadotropin releasing hormone (GnRH) secretion from the brain, which is finely modulated by a number of factors including gonadal sex steroids. GnRH cells do not express estrogen receptor α, but feedback is transmitted by neurons that are at least 'one step back' from the GnRH cells. Modulation by season, stress and nutrition are effected by neuronal pathways that converge on the GnRH cells. Kisspeptin and gonadotropin inhibitory hormone (GnIH) neurons are regulators of GnRH secretion, the former being a major conduit for transmission of sex steroid feedback. GnIH cells project to GnRH cells and may play a role in the seasonal changes in reproductive activity in sheep. GnIH also modulates the action of GnRH at the level of the pituitary gonadotrope. This review focuses on the role that kisspeptin and GnIH neurons play, as modulators that are 'one step back' from GnRH neurons.
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Wong KKY, Ng SYL, Lee LTO, Ng HKH, Chow BKC. Orexins and their receptors from fish to mammals: a comparative approach. Gen Comp Endocrinol 2011; 171:124-30. [PMID: 21216246 DOI: 10.1016/j.ygcen.2011.01.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 12/28/2010] [Accepted: 01/01/2011] [Indexed: 12/12/2022]
Abstract
Although recently discovered, orexins have been rapidly established as important neuropeptides in regulating physiological processes including food intake, sleep/wake cycles and reproduction through binding to two class B G protein-coupled receptors (OX1R and OX2R). To date, a handful of sequences for orexins and their receptors ranging from fish to mammalian species have been identified, allowing a glimpse into their evolution. Structurally, the genetic and molecular organization of the peptides and receptors amongst vertebrates are highly similar, underlining the strong evolutionary pressure that has been exerted to preserve structure and ultimately function. Furthermore, the absence of invertebrate orexin-like sequences suggests early vertebrates as the origin from which orexins evolved. With respect to the receptors, OX2R is probably evolutionary more ancient whilst OX1R is specific to mammalian species and evolved only during this later lineage. In common to all vertebrates studied, the hypothalamus remains to be the key brain region in which orexinergic neurons and fibers are localized in, establishing orexin to be an important player in regulating physiological processes especially those related to food intake and energy metabolism. To allow better understanding of the evolution of orexins and their receptors, this review will provide a comparative approach to their structures and functions in vertebrates.
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Affiliation(s)
- Kari K Y Wong
- School of Biological Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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Papargiris MM, Rivalland ETA, Clarke IJ, Smith JT, Pereira A, Tilbrook AJ. Evidence that RF-amide related peptide-3 is not a mediator of the inhibitory effects of psychosocial stress on gonadotrophin secretion in ovariectomised ewes. J Neuroendocrinol 2011; 23:208-15. [PMID: 21073555 DOI: 10.1111/j.1365-2826.2010.02094.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
It is well known that stress inhibits normal reproductive function, including gonadotrophin secretion; however, the mechanisms and mediators involved are largely unknown. Stress impairs the secretion of luteinising hormone (LH), and it has been suggested that the RF-amide gonadotrophin-inhibitory hormone (GnIH), known as RF-amide related peptide-3 (RFRP-3) in mammalian species, may mediate this inhibitory effect of stress. If this is the case, the GnIH/RFRP system would likely be up-regulated during stress. We tested this hypothesis in ovariectomised ewes using a psychosocial stressor: isolation/restraint. Ewes were randomly allocated to control or stress (n=5 per group). Isolation/restraint stress was imposed for 90 min after control sampling for 4 h, whereas control ewes were sampled continuously for 5.5 h. All ewes were then euthanased and brains were collected. As expected, plasma concentrations of cortisol were increased significantly (P<0.05) by stress and plasma concentrations of LH were significantly (P<0.05) reduced. Immunohistochemistry and in situ hybridisation were conducted for RFRP-3 peptide and RFRP mRNA expression, respectively, in the paraventricular nucleus/dorsal medial hypothalamus region of the hypothalamus. There was no significant effect of stress on RFRP-3 peptide or mRNA levels, with no differences between control or stress ewes. Furthermore, there was no difference in the number of RFRP-3 cells double-labelled for Fos between control and stress ewes and there was no difference in the cellular expression of RFRP mRNA between groups. These results indicate that the GnIH/RFRP system is not activated by psychosocial stress in ewes, suggesting that it is an unlikely mediator of the effects of stress on LH secretion.
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Affiliation(s)
- M M Papargiris
- Department of Physiology, Monash University, Victoria, Australia.
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Bhagwandin A, Fuxe K, Bennett NC, Manger PR. Distribution of orexinergic neurons and their terminal networks in the brains of two species of African mole rats. J Chem Neuroanat 2011; 41:32-42. [DOI: 10.1016/j.jchemneu.2010.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 11/01/2010] [Accepted: 11/03/2010] [Indexed: 10/18/2022]
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True C, Grove KL, Smith MS. Beyond Leptin: Emerging Candidates for the Integration of Metabolic and Reproductive Function during Negative Energy Balance. Front Endocrinol (Lausanne) 2011; 2:53. [PMID: 22645510 PMCID: PMC3355832 DOI: 10.3389/fendo.2011.00053] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 09/29/2011] [Indexed: 12/19/2022] Open
Abstract
Reproductive status is tightly coupled to metabolic state in females, and ovarian cycling in mammals is halted when energy output exceeds energy input, a metabolic condition known as negative energy balance. This inhibition of reproductive function during negative energy balance occurs due to suppression of gonadotropin-releasing hormone (GnRH) release in the hypothalamus. The GnRH secretagogue kisspeptin is also inhibited during negative energy balance, indicating that inhibition of reproductive neuroendocrine circuits may occur upstream of GnRH itself. Understanding the metabolic signals responsible for the inhibition of reproductive pathways has been a compelling research focus for many years. A predominant theory in the field is that the status of energy balance is conveyed to reproductive neuroendocrine circuits via the adipocyte hormone leptin. Leptin is stimulatory for GnRH release and lower levels of leptin during negative energy balance are believed to result in decreased stimulatory drive for GnRH cells. However, recent evidence found that restoring leptin to physiological levels did not restore GnRH function in three different models of negative energy balance. This suggests that although leptin may be an important permissive signal for reproductive function as indicated by many years of research, factors other than leptin must critically contribute to negative energy balance-induced reproductive inhibition. This review will focus on emerging candidates for the integration of metabolic status and reproductive function during negative energy balance.
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Affiliation(s)
- Cadence True
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science UniversityBeaverton, OR, USA
| | - Kevin L. Grove
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science UniversityBeaverton, OR, USA
| | - M. Susan Smith
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science UniversityBeaverton, OR, USA
- *Correspondence: M. Susan Smith, Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, 505 NW 185th Avenue, Beaverton, OR 97006, USA. e-mail:
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Sartin JL, Whitlock BK, Daniel JA. Triennial Growth Symposium: neural regulation of feed intake: modification by hormones, fasting, and disease. J Anim Sci 2010; 89:1991-2003. [PMID: 21148776 DOI: 10.2527/jas.2010-3399] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Appetite is a complex process that results from the integration of multiple signals at the hypothalamus. The hypothalamus receives neural signals; hormonal signals such as leptin, cholecystokinin, and ghrelin; and nutrient signals such as glucose, FFA, AA, and VFA. This effect is processed by a specific sequence of neurotransmitters beginning with the arcuate nucleus and orexigenic cells containing neuropeptide Y or agouti-related protein and anorexigenic cells containing proopiomelanocortin (yielding the neurotransmitter α-melanocyte-stimulating hormone) or cells expressing cocaine amphetamine-related transcript. These so-called first-order neurons act on second-order orexigenic neurons (containing either melanin-concentrating hormone or orexin) or act on anorexigenic neurons (e.g., expressing corticotropin-releasing hormone) to alter feed intake. In addition, satiety signals from the liver and gastrointestinal tract signal through the vagus nerve to the nucleus tractus solitarius to cause meal termination, and in combination with the hypothalamus, integrate the various signals to determine the feeding response. The activities of these neuronal pathways are also influenced by numerous factors such as nutrients, fasting, and disease to modify appetite and hence affect growth and reproduction. This review will begin with the central nervous system pathways and then discuss the ways in which hormones and metabolites may alter the process to affect feed intake with emphasis on farm animals.
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Affiliation(s)
- J L Sartin
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
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Distribution of orexin-A immunoreactive neurons and their terminal networks in the brain of the rock hyrax, Procavia capensis. J Chem Neuroanat 2010; 41:86-96. [PMID: 21126575 DOI: 10.1016/j.jchemneu.2010.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 11/21/2010] [Accepted: 11/21/2010] [Indexed: 11/21/2022]
Abstract
The present study describes the distribution of orexin-A immunoreactive neurons and terminal networks in relation to the previously described catecholaminergic, cholinergic and serotonergic systems within the brain of the rock hyrax, Procavia capensis. Adult female rock hyrax brains were sectioned and immunohistochemically stained with an antibody to orexin-A. The staining revealed that the neurons were mainly located within the hypothalamus as with other mammals. The orexinergic terminal network distribution also resembled the typical mammalian plan. High-density orexinergic terminal networks were located within regions of the diencephalon (e.g. paraventricular nuclei), midbrain (e.g. serotonergic nuclei) and pons (locus coeruleus), while medium density orexinergic terminal networks were evident in the telencephalic (e.g. basal forebrain), diencephalic (e.g. hypothalamus), midbrain (e.g. periaqueductal gray matter), pontine (e.g. serotonergic nuclei) and medullary regions (e.g. serotonergic and catecholaminergic nuclei). Although the distribution of the orexinergic terminal networks was typically mammalian, the rock hyrax did show one atypical feature, the presence of a high-density orexinergic terminal network within the anterodorsal nucleus of the dorsal thalamus (AD). The dense orexinergic innervation of the AD nucleus has only been reported previously in the Nile grass rat, Arvicanthis niloticus and Syrian hamster, Mesocricetus auratus, both diurnal mammals. It is possible that orexinergic innervation of the AD nucleus might be a unique feature associated with diurnal mammals. It was also noted that the dense orexinergic innervation of the AD nucleus coincided with previously identified cholinergic neurons and terminal networks in this particular nucleus of the rock hyrax brain. It is possible that this dense orexinergic innervation of the AD nucleus in the brain of the rock hyrax may act in concert with the cholinergic neurons and/or the cholinergic axonal terminals, which in turn may influence arousal states and motivational processing.
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Kruger JL, Dell LA, Pettigrew JD, Manger PR. Cellular location and major terminal networks of the orexinergic system in the brains of five microchiropteran species. J Chem Neuroanat 2010; 40:256-62. [DOI: 10.1016/j.jchemneu.2010.07.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 07/09/2010] [Accepted: 07/12/2010] [Indexed: 11/24/2022]
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The neuroendocrine basis of lactation-induced suppression of GnRH: role of kisspeptin and leptin. Brain Res 2010; 1364:139-52. [PMID: 20727862 DOI: 10.1016/j.brainres.2010.08.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/11/2010] [Accepted: 08/12/2010] [Indexed: 11/22/2022]
Abstract
Lactation is an important physiological model of the integration of energy balance and reproduction, as it involves activation of potent appetitive neuropeptide systems coupled to a profound inhibition of pulsatile GnRH/LH secretion. There are multiple systems that contribute to the chronic hyperphagia of lactation: 1) suppression of the metabolic hormones, leptin and insulin, 2) activation of hypothalamic orexigenic neuropeptide systems NPY, AGRP, orexin (OX) and melanin concentrating hormone (MCH), 3) special induction of NPY expression in the dorsomedial hypothalamus, and 4) suppression of anorexigenic systems POMC and CART. These changes ensure adequate energy intake to meet the metabolic needs of milk production. There is significant overlap in all of the systems that regulate food intake with the regulation of GnRH, suggesting there could be several redundant factors acting to suppress GnRH/LH during lactation. In addition to an overall increase in inhibitory tone acting directly on GnRH cell bodies that is brought about by increases in orexigenic systems, there are also effects at the ARH to disrupt Kiss1/neurokinin B/dynorphin neuronal function through inhibition of Kiss1 and NKB. These changes could lead to an increase in inhibitory auto-regulation of the Kiss1 neurons and a possible disruption of pulsatile GnRH release. While the low levels of leptin and insulin contribute to the changes in ARH appetitive systems, they do not appear to contribute to the suppression of ARH Kiss1 or NKB. The inhibition of Kiss1 may be the key factor in the suppression of GnRH during lactation, although the mechanisms responsible for its inhibition are unknown.
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López M, Tena-Sempere M, Diéguez C. Cross-talk between orexins (hypocretins) and the neuroendocrine axes (hypothalamic-pituitary axes). Front Neuroendocrinol 2010; 31:113-27. [PMID: 19654017 DOI: 10.1016/j.yfrne.2009.07.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 07/28/2009] [Accepted: 07/29/2009] [Indexed: 02/06/2023]
Abstract
Lesioning and electrical stimulation experiments carried out during the first half of the twentieth century showed that the lateral hypothalamic area (LHA) is involved in the neuroendocrine control of hormone secretion. However, the molecular basis of this phenomenon remained unclear until fifty years later when in 1998, two different laboratories discovered a new family of hypothalamic neuropeptides, the orexins or hypocretins (OX-A/Hcrt1 and OX-B/Hcrt2). Since then, remarkable evidence has revealed that orexins/hypocretins play a prominent role in regulating virtually all the neuroendocrine axes, acting as pivotal signals in the coordination of endocrine responses with regards to sleep, arousal and energy homeostasis. The clinical relevance of these actions is supported by human data showing impairment of virtually all the neuroendocrine axes in orexin/hypocretin-deficient narcoleptic patients. Here, we summarize more than ten years of knowledge about the orexins/hypocretins with particular focus on their role as neuroendocrine regulators. Understanding this aspect of orexin/hypocretin physiology could open new therapeutic possibilities in the treatment of sleep, energy homeostasis and endocrine pathologies.
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Affiliation(s)
- Miguel López
- Department of Physiology, School of Medicine, University of Santiago de Compostela - Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain.
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41
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Silveyra P, Cataldi NI, Lux-Lantos VA, Libertun C. Role of orexins in the hypothalamic-pituitary-ovarian relationships. Acta Physiol (Oxf) 2010; 198:355-60. [PMID: 19796256 DOI: 10.1111/j.1748-1716.2009.02049.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Appropriate nutritional and vigilance states are needed for reproduction. In previous works, we described the influence of the hormonal milieu of proestrus on the orexinergic system and we found that orexin receptor 1 expression in the hypothalamus, but not other neural areas, and the adenohypophysis was under the influence of oestradiol and the time of the day. Information from the sexual hormonal milieu of proestrous afternoon impacts on various components of the orexinergic system and alertness on this particular night of proestrus would be of importance for successful reproduction. In this review, we summarize the available experimental data supporting the participation of orexins in the hypothalamic-pituitary-ovarian relationships. All together, these results suggest a role of the orexinergic system as an integrative link among vital functions such as reproduction, food intake, alertness and the inner biological clock.
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Affiliation(s)
- P Silveyra
- Instituto de Biología y Medicina Experimental-CONICET, Buenos Aires, Argentina
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Backholer K, Smith J, Clarke IJ. Melanocortins may stimulate reproduction by activating orexin neurons in the dorsomedial hypothalamus and kisspeptin neurons in the preoptic area of the ewe. Endocrinology 2009; 150:5488-97. [PMID: 19819961 DOI: 10.1210/en.2009-0604] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To further test the hypothesis that melanocortins stimulate the reproductive axis, we treated ewes with melanocortin agonist (MTII) in the luteal phase of the estrous cycle and during seasonal anestrus. Lateral ventricular infusion of MTII (10 microg/h) during the luteal phase increased LH secretion. Retrograde neuronal tracing in the brain showed few proopiomelanocortin or kisspeptin cells in the arcuate nucleus, but more than 70% of kisspeptin cells in the dorsolateral preoptic area (POA), projecting to the ventromedial POA in which GnRH cells are located. MTII infusion (20 h) was repeated in luteal phase ewes and brains were harvested to measure gene expression of preproorexin and kisspeptin. Expression of orexin in the dorsomedial hypothalamus and kisspeptin in the POA was up-regulated by MTII treatment and Kiss1 in the arcuate nucleus was down-regulated. Seasonally anestrous ewes were progesterone primed and then treated (lateral ventricular) with MTII (10 microg/h) or vehicle for 30 h, and blood samples were collected every 2 h from 4 h before infusion until 6 h afterward to monitor acute response in terms of LH levels. A rise in basal LH levels was seen, but samples collected around the time of the predicted LH surge did not indicate that an ovulatory event occurred. We conclude that melanocortins are positive regulators of the reproductive neuroendocrine system, but treatment with melanocortins does not fully overcome seasonal acyclicity. The stimulatory effect of melanocortin in the luteal phase of the estrous cycle may be via the activation of kisspeptin cells in the POA and/or orexin cells in the dorsomedial hypothalamus.
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Affiliation(s)
- Kathryn Backholer
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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Clarke IJ, Sari IP, Qi Y, Smith JT, Parkington HC, Ubuka T, Iqbal J, Li Q, Tilbrook A, Morgan K, Pawson AJ, Tsutsui K, Millar RP, Bentley GE. Potent action of RFamide-related peptide-3 on pituitary gonadotropes indicative of a hypophysiotropic role in the negative regulation of gonadotropin secretion. Endocrinology 2008; 149:5811-21. [PMID: 18617613 DOI: 10.1210/en.2008-0575] [Citation(s) in RCA: 256] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We identified a gene in the ovine hypothalamus encoding for RFamide-related peptide-3 (RFRP-3), and tested the hypothesis that this system produces a hypophysiotropic hormone that inhibits the function of pituitary gonadotropes. The RFRP-3 gene encodes for a peptide that appears identical to human RFRP-3 homolog. Using an antiserum raised against RFRP-3, cells were localized to the dorsomedial hypothalamic nucleus/paraventricular nucleus of the ovine brain and shown to project to the neurosecretory zone of the ovine median eminence, predicating a role for this peptide in the regulation of anterior pituitary gland function. Ovine RFRP-3 peptide was tested for biological activity in vitro and in vivo, and was shown to reduce LH and FSH secretion in a specific manner. RFRP-3 potently inhibited GnRH-stimulated mobilization of intracellular calcium in gonadotropes. These data indicate that RFRP-3 is a specific and potent mammalian gonadotropin-inhibiting hormone, and that it acts upon pituitary gonadotropes to reduce GnRH-stimulated gonadotropin secretion.
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Affiliation(s)
- Iain J Clarke
- Department Physiology, Building 13F, Monash University, Clayton Victoria 3800, Australia.
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Hoskins LJ, Xu M, Volkoff H. Interactions between gonadotropin-releasing hormone (GnRH) and orexin in the regulation of feeding and reproduction in goldfish (Carassius auratus). Horm Behav 2008; 54:379-85. [PMID: 18544455 DOI: 10.1016/j.yhbeh.2008.04.011] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2008] [Revised: 04/23/2008] [Accepted: 04/28/2008] [Indexed: 11/25/2022]
Abstract
Links between energy homeostasis and reproduction have been demonstrated in vertebrates. As a general rule, abundant food resources favor reproduction whereas low food availability induces an inhibition of reproductive processes. In both mammals and fish, gonadotropin-releasing hormone (GnRH) and orexin (OX) are hypothalamic neuropeptides that play critical roles in the regulation of sexual behavior and appetite, respectively. In order to assess possible interactions between orexin and GnRH in the control of feeding and reproduction in goldfish, we examined the effects of chicken GnRH (cGnRH-II) intracerebroventricular (ICV) injection on feeding behavior and OX brain mRNA expression as well as the effects of orexin ICV injections on spawning behavior and cGnRH-II brain mRNA expression. Treatment with cGnRH-II at doses that stimulate spawning (0.5 ng/g or 1 ng/g) resulted in a decrease in both food intake and hypothalamic orexin mRNA expression. Treatment with orexin A at doses that stimulate feeding (10 ng/g) induced an inhibition of spawning behavior and a decrease in cGnRH-II expression in the hypothalamus and optic tectum-thalamus. Our results suggest that the anorexigenic actions of cGnRH-II in goldfish might be in part mediated by OX and that orexin inhibits reproductive behavior in part via the inhibition of the GnRH system. Our data suggest the existence of a coordinated control of feeding and reproduction by the orexin and GnRH systems in goldfish.
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Affiliation(s)
- Leah J Hoskins
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada A1B 3X9
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Suzuki H, Kubo Y, Yamamoto T. Orexin-A immunoreactive cells and fibers in the central nervous system of the axolotl brain and their association with tyrosine hydroxylase and serotonin immunoreactive somata. J Chem Neuroanat 2008; 35:295-305. [DOI: 10.1016/j.jchemneu.2008.02.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 02/13/2008] [Accepted: 02/13/2008] [Indexed: 11/25/2022]
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46
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Matsuda K, Nakamura K, Shimakura SI, Miura T, Kageyama H, Uchiyama M, Shioda S, Ando H. Inhibitory effect of chicken gonadotropin-releasing hormone II on food intake in the goldfish, Carassius auratus. Horm Behav 2008; 54:83-9. [PMID: 18342861 DOI: 10.1016/j.yhbeh.2008.01.011] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2007] [Revised: 01/29/2008] [Accepted: 01/30/2008] [Indexed: 11/22/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) is an evolutionarily conserved neuropeptide with 10 amino acid residues, which possesses some structural variants. A molecular form known as chicken GnRH II ([His(5) Trp(7) Tyr(8)] GnRH, cGnRH II) is widely distributed in vertebrates, and has recently been implicated in the regulation of sexual behavior and food intake in an insectivore, the musk shrew. However, the influence of cGnRH II on feeding behavior has not yet been studied in model animals such as rodents and teleost fish. In this study, therefore, we investigated the role of cGnRH II in the regulation of feeding behavior in the goldfish, and examined its involvement in food intake after intracerebroventricular (ICV) administration. ICV-injected cGnRH II at graded doses, from 0.1 to 10 pmol/g body weight (BW), induced a decrease of food consumption in a dose-dependent manner during 60 min after treatment. Cumulative food intake was significantly decreased by ICV injection of cGnRH II at doses of 1 and 10 pmol/g BW during the 60-min post-treatment observation period. ICV injection of salmon GnRH ([Trp(7) Leu(8)] GnRH, sGnRH) at doses of 0.1-10 pmol/g BW did not affect food intake. The anorexigenic action of cGnRH II was completely blocked by treatment with the GnRH type I receptor antagonist, Antide. However, the anorexigenic action of cGnRH II was not inhibited by treatment with the corticotropin-releasing hormone (CRH) 1/2 receptor antagonist, *-helical CRH((9-41)), and the melanocortin 4 receptor antagonist, HS024. These results suggest that, in the goldfish, cGnRH II, but not sGnRH, acts as an anorexigenic factor, as is the case in the musk shrew, and that the anorexigenic action of cGnRH II is independent of CRH- and melanocortin-signaling pathways.
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Affiliation(s)
- Kouhei Matsuda
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan.
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Su J, Lei Z, Zhang W, Ning H, Ping J. Distribution of orexin B and its relationship with GnRH in the pig hypothalamus. Res Vet Sci 2008; 85:315-23. [PMID: 18255106 DOI: 10.1016/j.rvsc.2007.12.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 11/28/2007] [Accepted: 12/11/2007] [Indexed: 11/30/2022]
Abstract
Increasing evidence suggests that orexins--hypothalamic neuropeptides--act as neurotransmitters or neuromediators in the brain, regulating autonomic and neuroendocrine functions. Orexins are closely associated with gonadotropin-releasing hormone (GnRH) neurons in the preoptic area and alter luteinizing hormone (LH) release, suggesting that they regulate reproduction. Here, we investigated the distribution of orexin B (immunohistochemical technique) and the relationship between orexin B and GnRH containing fibres and neurons in the pig hypothalamus using double immunofluorescence and laser-scanning confocal microscopy. Orexin B immunoreactive neurons were mainly localized in the perifornical area (PeF), dorsomedial hypothalamic nucleus (DMH), zona incerta (ZI) and the posterior hypothalamic area (PH), with a sparser distribution in the preoptic and anterior hypothalamic area. Immunoreactive fibres were distributed throughout the central nervous system. Approximately 30% GnRH neurons were in close contact with orexin B immunoreactive fibres, among these approximately 6% of GnRH neurons co-localized with orexin B perikarya in the region between the caudal preoptic area and the anterior hypothalamic area. Orexin B may regulate reproduction by altering LH release in the hypothalamus.
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Affiliation(s)
- Juan Su
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China
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Silveyra P, Lux-Lantos V, Libertun C. Both orexin receptors are expressed in rat ovaries and fluctuate with the estrous cycle: effects of orexin receptor antagonists on gonadotropins and ovulation. Am J Physiol Endocrinol Metab 2007; 293:E977-85. [PMID: 17638707 DOI: 10.1152/ajpendo.00179.2007] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Orexins are peptides controlling feeding, sleep, and neuroendocrine functions. They are synthesized by the hypothalamus with projections throughout the brain. Orexins and their orexin 1 (OX(1)) and orexin 2 receptors (OX(2)) are present outside the central nervous system. Here the expression of preproorexin (PPO), OX(1), and OX(2) was studied in rat ovaries. PPO, OX(1), and OX(2) were determined by quantitative real-time RT-PCR in ovaries of cycling Sprague-Dawley rats on all days of the cycle. Serum hormones and food consumption were determined. Ovarian OX(1) and OX(2) expression was then studied after ovulation blockade with Cetrorelix or Nembutal. Finally, proestrous rats were treated at 1400 and 1900 with a selective OX(1) antagonist (SB-334867-A) and/or a selective OX(2) antagonist (JNJ-10397049), and hormone levels, ovulation, and ovarian histology were studied. Both receptors' expression increased in the ovary between 1700 and 2300 of proestrus exclusively, in coincidence with hormone peaks, but not with the dark-light cycle or food intake. PPO was not detected. Cetrorelix or Nembutal prevented the increases of OX(1) and OX(2) while blunting gonadotropin peaks. SB-334867-A and JNJ-10397049, alone or combined, decreased serum gonadotropins and reduced ova number the following morning; ovaries showed a bloody (hyperemic and/or hemorrhagic) reaction with more preovulatory follicles and less corpora lutea. Here we demonstrate for the first time an increased ovarian expression of both OX(1) and OX(2), only during proestrous afternoon, and its hormone dependence but not dependence on the dark-light cycle. Two new receptor antagonists reduced proestrous gonadotropins and/or ova number while producing ovarian structural changes.
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Affiliation(s)
- Patricia Silveyra
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Argentina
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Amiya N, Amano M, Oka Y, Iigo M, Takahashi A, Yamamori K. Immunohistochemical localization of orexin/hypocretin-like immunoreactive peptides and melanin-concentrating hormone in the brain and pituitary of medaka. Neurosci Lett 2007; 427:16-21. [DOI: 10.1016/j.neulet.2007.07.043] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 07/26/2007] [Accepted: 07/26/2007] [Indexed: 10/23/2022]
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Iwasa T, Matsuzaki T, Kiyokawa M, Shimizu F, Minakuchi M, Kuwahara A, Maegawa M, Yasui T, Irahara M. The type 2 corticotrophin-releasing hormone receptor mediates orexin A-induced luteinising hormone suppression in ovariectomised rats. J Neuroendocrinol 2007; 19:732-8. [PMID: 17680889 DOI: 10.1111/j.1365-2826.2007.01583.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Orexins are thought to be regulatory factors of the arousal and sleep patterns. They also affect immune, feeding, autonomic and neuroendocrine systems. We have previously shown that intracerebroventricular (i.c.v.) injection of orexin decreases pulsatile luteinising hormone (LH) secretion in ovariectomised (OVX) rats. However, the details of this mechanism have not been fully examined. Intracerebroventricular injection of orexin A also stimulates corticotrophin-releasing hormone (CRH) systems, which have been implicated in the stress-induced suppression of reproductive function. In the present study, we investigated the role of CRH systems in orexin-induced LH suppression. OVX rats were implanted with i.c.v. and intravenous (i.v.) cannulae. After i.c.v. injection of orexin and/or CRH receptor antagonists, blood samples were collected through the i.v. cannula at 6-min intervals for 120 min for LH measurement. Intracerebroventricular injection of orexin A or B (3 nmol/2.5 microl) suppressed pulsatile LH secretion. Coadministration of orexin A and alpha-helical corticotrophic-releasing factor (CRF), a nonselective CRH receptor antagonist (13 nmol/2.5 microl), or astressin(2)B, a selective type2 (CRH-R2) CRH receptor antagonist (28 nmol/2.5 microl), partly restored pulsatile LH secretion. Orexin B-induced LH suppression was not restored by alpha-helical CRF. In addition, i.c.v. injection of orexin A increased CRH and urocortin II (UcnII), but not Ucn mRNA levels, in the hypothalamus. These findings suggest that CRH-R2 mediates orexin A-induced LH suppression and it is possible that CRH and UcnII in the hypothalamus are involved in this pathway.
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Affiliation(s)
- T Iwasa
- Department of Obstetrics and Gynecology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima 770-8503, Japan.
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