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Fukunaga K, Takeuchi Y, Yamauchi C, Takemura A. Induction of spawning under artificial moonlight in the honeycomb grouper Epinephelus merra, a lunar-synchronized spawner. BIOL RHYTHM RES 2022. [DOI: 10.1080/09291016.2022.2046416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Kodai Fukunaga
- Center for Strategic Research Project, University of the Ryukyus, Nishihara, Japan
| | - Yuki Takeuchi
- Okinawa Institute of Science and Technology Graduate School, Okinawa, Japan
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2
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Oishi A, Gbahou F, Jockers R. Melatonin receptors, brain functions, and therapies. HANDBOOK OF CLINICAL NEUROLOGY 2021; 179:345-356. [PMID: 34225974 DOI: 10.1016/b978-0-12-819975-6.00022-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In mammals, including humans, the neurohormone melatonin is mainly secreted from the pineal gland at night and acts on two high-affinity G protein-coupled receptors, the melatonin MT1 and MT2 receptors. Major functions of melatonin receptors in the brain are the regulation of circadian rhythms and sleep. Correspondingly, the main indications of the currently available drugs for these receptors indicate this as targets. Yet these drugs may not only improve circadian rhythm- and sleep-related disorders but may also be beneficial for complex diseases like major depression, Alzheimer's disease, autism, and attention-deficit/hyperactivity disorders. Here, we will focus on the hypothalamic functions of melatonin receptors by updating our knowledge on their hypothalamic expression pattern at normal, aged, and disease states, by discussing their capacity to regulate circadian rhythms and sleep and by presenting the clinical applications of the melatonin receptor-targeting drugs ramelteon, tasimelteon, and agomelatine or of prolonged-release melatonin formulations. Finally, we speculate about future trends in the field of melatonin receptor drugs.
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Affiliation(s)
- Atsuro Oishi
- Institut Cochin, Université de Paris, Paris, France
| | | | - Ralf Jockers
- Institut Cochin, Université de Paris, Paris, France.
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3
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Frare C, Williams CT, Drew KL. Thermoregulation in hibernating mammals: The role of the "thyroid hormones system". Mol Cell Endocrinol 2021; 519:111054. [PMID: 33035626 PMCID: PMC8091518 DOI: 10.1016/j.mce.2020.111054] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/15/2020] [Accepted: 10/04/2020] [Indexed: 12/19/2022]
Abstract
Hibernation is a unique evolutionary adaptation to conserve energy. During the pre-hibernation (i.e. fall) season, a progressive decline in core body temperature and further decrease in metabolism underlie a seasonal modulation in thermoregulation. The onset of hibernation requires marked changes in thermoregulatory attributes including adjustment in body temperature and tissue specific increases in thermogenic capacity. The hibernation season is characterized by a regulated suppression in thermogenesis allowing the onset of torpor interrupted by periodic activation of thermogenesis to sustain interbout arousals. Thyroid hormones are known to regulate both body temperature and metabolism, and for this reason, the hypothalamic-pituitary-thyroid axis and thyroid hormones have been investigated as modulators of thermogenesis in the phenomenon of hibernation, but the mechanisms remain poorly understood. In this review, we present an overview of what is known about the thermogenic roles of thyroid hormones in hibernating species across seasons and within the hibernating season (torpor-interbout arousal cycle). Overall, the hypothalamic-pituitary-thyroid axis and thyroid hormones play a role in the pre-hibernation season to enhance thermogenic capacity. During hibernation, thermogenesis is attenuated at the level of sympathetic premotor neurons within the raphe pallidus and by deiodinase expression in the hypothalamus. Further, as recent work highlights the direct effect of thyroid hormones within the central nervous system in activating thermogenesis, we speculate how similar mechanisms may occur in hibernating species to modulate thermogenesis across seasons and to sustain interbout arousals. However, further experiments are needed to elucidate the role of thyroid hormones in hibernation, moving towards the understanding that thyroid hormones metabolism, transport and availability within tissues may be the most telling indicator of thyroid status.
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Affiliation(s)
- C Frare
- Department of Chemistry and Biochemistry University of Alaska Fairbanks, Fairbanks, AK, 99775, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA
| | - Cory T Williams
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA; Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Kelly L Drew
- Department of Chemistry and Biochemistry University of Alaska Fairbanks, Fairbanks, AK, 99775, USA; Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks 2140 Koyukuk Drive, Fairbanks, AK, 99775, USA.
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4
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Yoo S, Cha D, Kim S, Jiang L, Cooke P, Adebesin M, Wolfe A, Riddle R, Aja S, Blackshaw S. Tanycyte ablation in the arcuate nucleus and median eminence increases obesity susceptibility by increasing body fat content in male mice. Glia 2020; 68:1987-2000. [PMID: 32173924 PMCID: PMC7423758 DOI: 10.1002/glia.23817] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/28/2020] [Accepted: 02/28/2020] [Indexed: 12/11/2022]
Abstract
Tanycytes are radial glial cells located in the mediobasal hypothalamus. Recent studies have proposed that tanycytes play an important role in hypothalamic control of energy homeostasis, although this has not been directly tested. Here, we report the phenotype of mice in which tanycytes of the arcuate nucleus and median eminence were conditionally ablated in adult mice. Although the cerebrospinal fluid-hypothalamic barrier was rendered more permeable following tanycyte ablation, neither the blood-hypothalamic barrier nor leptin-induced pSTAT3 activation in hypothalamic parenchyma were affected. We observed a significant increase in visceral fat distribution accompanying insulin insensitivity in male mice, without significant effect on either body weight or food intake. A high-fat diet tended to accelerate overall body weight gain in tanycyte-ablated mice, but the development of visceral adiposity and insulin insensitivity was comparable to wildtype. Thermoneutral housing exacerbated fat accumulation and produced a shift away from fat oxidation in tanycyte-ablated mice. These results clarify the extent to which tanycytes regulate energy balance, and demonstrate a role for tanycytes in regulating fat metabolism.
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Affiliation(s)
- Sooyeon Yoo
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David Cha
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Soohyun Kim
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Lizhi Jiang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Patrick Cooke
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Mobolanie Adebesin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Andrew Wolfe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ryan Riddle
- Department of Orthopedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Baltimore Veterans Administration Medical Center, Baltimore, Maryland
| | - Susan Aja
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Center for Human Systems Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
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5
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Bizzarri M. Advances in Characterizing Recently-Identified Molecular Actions of Melatonin: Clinical Implications. APPROACHING COMPLEX DISEASES 2020. [PMCID: PMC7164543 DOI: 10.1007/978-3-030-32857-3_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Melatonin, N-acetyl-5-methoxy-tryptamine, was discovered to be a product of serotonin metabolism in the mammalian pineal gland where its synthesis is under control of the light:dark cycle. Besides its regulatory pathway involving ganglion cells in the retina, the neural connections between the eyes and the pineal gland include the master circadian clock, the suprachiasmatic nuclei, and the central and peripheral nervous systems. Since pineal melatonin is released into the blood and into the cerebrospinal fluid, it has access to every cell in an organism and it mediates system-wide effects. Subsequently, melatonin was found in several extrapineal organs and, more recently, perhaps in every cell of every organ. In contrast to the pinealocytes, non-pineal cells do not discharge melatonin into the blood; rather it is used locally in an intracrine, autocrine, or paracrine manner. Melatonin levels in non-pineal cells do not exhibit a circadian rhythm and do not depend on circulating melatonin concentrations although when animals are treated with exogenous melatonin it is taken up by presumably all cells. Mitochondria are the presumed site of melatonin synthesis in all cells; the enzymatic machinery for melatonin synthesis has been identified in mitochondria. The association of melatonin with mitochondria, because of its ability to inhibit oxidative stress, is very fortuitous since these organelles are a major site of damaging reactive oxygen species generation. In this review, some of the actions of non-pineal-derived melatonin are discussed in terms of cellular and subcellular physiology.
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Affiliation(s)
- Mariano Bizzarri
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
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Wang D, Li N, Tian L, Ren F, Li Z, Chen Y, Liu L, Hu X, Zhang X, Song Y, Hut RA, Liu XH. Dynamic expressions of hypothalamic genes regulate seasonal breeding in a natural rodent population. Mol Ecol 2019; 28:3508-3522. [PMID: 31233652 DOI: 10.1111/mec.15161] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 05/22/2019] [Accepted: 06/04/2019] [Indexed: 12/31/2022]
Abstract
Seasonal breeding is a universal reproductive strategy in many animals. Hypothalamic genes, especially type 2 and 3 iodothyronine deiodinases (Dio2/3), RFamide-related peptide 3 (Rfrp-3), kisspeptin (Kiss-1) and gonadotropin-releasing hormone (GnRH), are involved in a photoperiodic pathway that encodes seasonal signals from day length in many vertebrate species. However, the seasonal expression patterns of these genes in wild mammals are less studied. Here, we present a four-year field investigation to reveal seasonal rhythm and age-dependent reproductive activity in male Brandt's voles (Lasiopodomys brandtii) and to detect relationships among seasonal expression profiles of hypothalamic genes, testicular activity, age and annual day length. From breeding season (April) to nonbreeding season (October), adult male voles displayed a synchronous peak in gonadal activity with annual day length around summer solstice, which was jointly caused by age structure shifts and age-dependent gonadal development patterns. Overwintered males maintained reproductive activity until late in the breeding season, whereas most newborn males terminated gonadal development completely, except for a minority of males born early in spring. Consistently, the synchronous and opposite expression profiles of Dio2/3 suggest their central function to decode photoperiodic signals and to predict the onset of the nonbreeding season. Moreover, changes in Dio2/3 signals may guide the actions of Kiss-1 and Rfrp-3 to regulate the age-dependent divergence of reproductive strategy in wild Brandt's vole. Our results provide evidence on how hypothalamic photoperiod genes regulate seasonal breeding in a natural rodent population.
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Affiliation(s)
- Dawei Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ning Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lin Tian
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Fei Ren
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhengguang Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yan Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,College of Life Sciences, Sichuan University, Chengdu, China
| | - Lan Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.,College of Life Sciences, Sichuan University, Chengdu, China
| | - Xiangfa Hu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xuechang Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Ying Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Roelof A Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Xiao-Hui Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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Rodríguez E, Guerra M, Peruzzo B, Blázquez JL. Tanycytes: A rich morphological history to underpin future molecular and physiological investigations. J Neuroendocrinol 2019; 31:e12690. [PMID: 30697830 DOI: 10.1111/jne.12690] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 01/04/2023]
Abstract
Tanycytes are located at the base of the brain and retain characteristics from their developmental origins, such as radial glial cells, throughout their life span. With transport mechanisms and modulation of tight junction proteins, tanycytes form a bridge connecting the cerebrospinal fluid with the external limiting basement membrane. They also retain the powers of self-renewal and can differentiate to generate neurones and glia. Similar to radial glia, they are a heterogeneous family with distinct phenotypes. Although the four subtypes so far distinguished display distinct characteristics, further research is likely to reveal new subtypes. In this review, we have re-visited the work of the pioneers in the field, revealing forgotten work that is waiting to inspire new research with today's cutting-edge technologies. We have conducted a systematic ultrastructural study of α-tanycytes that resulted in a wealth of new information, generating numerous questions for future study. We also consider median eminence pituicytes, a closely-related cell type to tanycytes, and attempt to relate pituicyte fine morphology to molecular and functional mechanism. Our rationale was that future research should be guided by a better understanding of the early pioneering work in the field, which may currently be overlooked when interpreting newer data or designing new investigations.
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Affiliation(s)
- Esteban Rodríguez
- Facultad de Medicina, Instituto de Anatomía, Histología y Patología, Universidad Austral de Chile, Valdivia, Chile
| | - Montserrat Guerra
- Facultad de Medicina, Instituto de Anatomía, Histología y Patología, Universidad Austral de Chile, Valdivia, Chile
| | - Bruno Peruzzo
- Facultad de Medicina, Instituto de Anatomía, Histología y Patología, Universidad Austral de Chile, Valdivia, Chile
| | - Juan Luis Blázquez
- Departamento de Anatomía e Histología Humanas, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
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8
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Abstract
Organisms use changes in photoperiod for seasonal reproduction to maximize the survival of their offspring. Birds have sophisticated seasonal mechanisms and are therefore excellent models for studying these phenomena. Birds perceive light via deep-brain photoreceptors and long day–induced thyroid-stimulating hormone (TSH, thyrotropin) in the pars tuberalis of the pituitary gland (PT), which cause local thyroid hormone activation within the mediobasal hypothalamus. The local bioactive thyroid hormone controls seasonal gonadotropin-releasing hormone secretion and subsequent gonadotropin secretion. In mammals, the eyes are believed to be the only photoreceptor organ, and nocturnal melatonin secretion triggers an endocrine signal that communicates information about the photoperiod to the PT to regulate TSH. In contrast, in Salmonidae fish the input pathway to the neuroendocrine output pathway appears to be localized in the saccus vasculosus. Thus, comparative analysis is an effective way to uncover the universality and diversity of fundamental traits in various organisms.
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Affiliation(s)
- Yusuke Nakane
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Laboratory of Animal Integrative Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Takashi Yoshimura
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Laboratory of Animal Integrative Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
- Division of Seasonal Biology, National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan
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GUH YJ, TAMAI TK, YOSHIMURA T. The underlying mechanisms of vertebrate seasonal reproduction. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:343-357. [PMID: 31406058 PMCID: PMC6766453 DOI: 10.2183/pjab.95.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/24/2019] [Indexed: 06/01/2023]
Abstract
Animals make use of changes in photoperiod to adapt their physiology to the forthcoming breeding season. Comparative studies have contributed to our understanding of the mechanisms of seasonal reproduction in vertebrates. Birds are excellent models for studying these phenomena because of their rapid and dramatic responses to changes in photoperiod. Deep brain photoreceptors in birds perceive and transmit light information to the pars tuberalis (PT) in the pituitary gland, where the thyroid-stimulating hormone (TSH) is produced. This PT-TSH locally increases the level of the bioactive thyroid hormone T3 via the induction of type 2 deiodinase production in the mediobasal hypothalamus, and an increased T3 level, in turn, controls seasonal gonadotropin-releasing hormone secretion. In mammals, the eyes are the only photoreceptive structure, and nocturnal melatonin secretion encodes day-length information and regulates the PT-TSH signaling cascade. In Salmonidae, the saccus vasculosus plays a pivotal role as a photoperiodic sensor. Together, these studies have uncovered the universality and diversity of fundamental traits in vertebrates.
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Affiliation(s)
- Ying-Jey GUH
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Aichi, Japan
- Division of Seasonal Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
| | - Takako K TAMAI
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Aichi, Japan
| | - Takashi YOSHIMURA
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Aichi, Japan
- Division of Seasonal Biology, National Institute for Basic Biology, Okazaki, Aichi, Japan
- Laboratory of Integrative Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, Japan
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Kriegsfeld LJ, Jennings KJ, Bentley GE, Tsutsui K. Gonadotrophin-inhibitory hormone and its mammalian orthologue RFamide-related peptide-3: Discovery and functional implications for reproduction and stress. J Neuroendocrinol 2018; 30:e12597. [PMID: 29624758 PMCID: PMC6263162 DOI: 10.1111/jne.12597] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/26/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023]
Abstract
At the turn of the millennium, a neuropeptide with pronounced inhibitory actions on avian pituitary gonadotrophin secretion was identified and named gonadotrophin-inhibitory hormone (GnIH). Across bird species, GnIH acts at the level of the pituitary and the gonadotrophin-releasing hormone (GnRH) neuronal system to inhibit reproduction. Subsequent to this initial discovery, orthologues of GnIH have been identified and characterised across a broad range of species. In many vertebrates, the actions of GnIH and its orthologues serve functional roles analogous to those seen in birds. In other cases, GnIH and its orthologues exhibit more diverse actions dependent on sex, species, season and reproductive condition. The present review highlights the discovery and functional implications of GnIH across species, focusing on research domains in which the significance of this neuropeptide has been explored most.
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Affiliation(s)
- Lance J. Kriegsfeld
- Department of Psychology, University of California, Berkeley, California 94720, USA
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
- Corresponding Author: Lance J. Kriegsfeld, Ph.D. Neurobiology Laboratory, Department of Psychology and The Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, California 94720-1650, USA, Phone: (510) 642-5148; Fax: (510) 642-5293;
| | - Kimberly J. Jennings
- Department of Psychology, University of California, Berkeley, California 94720, USA
| | - George E. Bentley
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
- Department of Integrative Biology, University of California, Berkeley, California 94720, USA
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
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viviD D, Bentley GE. Seasonal Reproduction in Vertebrates: Melatonin Synthesis, Binding, and Functionality Using Tinbergen's Four Questions. Molecules 2018; 23:E652. [PMID: 29534047 PMCID: PMC6017951 DOI: 10.3390/molecules23030652] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/11/2018] [Accepted: 02/13/2018] [Indexed: 12/15/2022] Open
Abstract
One of the many functions of melatonin in vertebrates is seasonal reproductive timing. Longer nights in winter correspond to an extended duration of melatonin secretion. The purpose of this review is to discuss melatonin synthesis, receptor subtypes, and function in the context of seasonality across vertebrates. We conclude with Tinbergen's Four Questions to create a comparative framework for future melatonin research in the context of seasonal reproduction.
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Affiliation(s)
- Dax viviD
- Berkeley Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
| | - George E Bentley
- Berkeley Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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12
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Korf HW. Signaling pathways to and from the hypophysial pars tuberalis, an important center for the control of seasonal rhythms. Gen Comp Endocrinol 2018; 258:236-243. [PMID: 28511899 DOI: 10.1016/j.ygcen.2017.05.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/09/2017] [Accepted: 05/12/2017] [Indexed: 11/28/2022]
Abstract
Seasonal (circannual) rhythms play an important role for the control of body functions (reproduction, metabolism, immune responses) in nearly all living organisms. Also humans are affected by the seasons with regard to immune responses and mental functions, the seasonal affective disorder being one of the most prominent examples. The hypophysial pars tuberalis (PT), an important interface between the hypophysial pars distalis and neuroendocrine centers in the brain, plays an essential role in the regulation of seasonal functions and may even be the seat of the circannual clock. Photoperiodic signals provide a major input to the PT. While the perception of these signals involves extraocular photoreceptors in non-mammalian species (birds, fish), mammals perceive photoperiodic signals exclusively in the retina. A multisynaptic pathway connects the retina with the pineal organ where photoperiodic signals are translated into the neurohormone melatonin that is rhythmically produced night by night and encodes the length of the night. Melatonin controls the functional activity of the mammalian PT by acting upon MT1 melatonin receptors. The PT sends its output signals via retrograde and anterograde pathways. The retrograde pathway targetting the hypothalamus employs TSH as messenger and controls a local hypothalamic T3 system. As discovered in Japanese quail, TSH triggers molecular cascades mediating thyroid hormone conversion in the ependymal cell layer of the infundibular recess of the third ventricle. The local accumulation of T3 in the mediobasal hypothalamus (MBH) appears to activate the gonadal axis by affecting the neuro-glial interaction between GnRH terminals and tanycytes in the median eminence. This retrograde pathway is conserved in photoperiodic mammals (sheep and hamsters), and even in non-photoperiodic laboratory mice provided that they are capable to synthesize melatonin. The anterograde pathway is implicated in the control of prolactin secretion, targets cells in the PD and supposedly employs small molecules as signal substances collectively denominated as "tuberalins". Several "tuberalin" candidates have been proposed, such as tachykinins, the secretory protein TAFA and endocannabinoids (EC). The PT-intrinsic EC system was first demonstrated in Syrian hamsters and shown to respond to photoperiodic changes. Subsequently, the EC system was also demonstrated in the PT of mice, rats and humans. To date, 2-arachidonoylglycerol (2-AG) appears as the most important endocannabinoid from the PT. Likely targets for the EC are folliculo-stellate cells that contain the CB1 receptor and appear to contact lactotroph cells. The CB1 receptor was also found on corticotroph cells which appear as a further target of the EC. Recently, the CB1 receptor was also localized to CRF-containing nerve fibers running in the outer zone of the median eminence. This finding suggests that the EC system of the PT contributes not only to the anterograde, but also to the retrograde pathway. Taken together, the results support the concept that the PT transmits its signals via a "cocktail" of messenger molecules which operate also in other brain areas and systems rather than through PT-specific "tuberalins". Furthermore, they may attribute a novel function to the PT, namely the modulation of the stress response and immune functions.
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Affiliation(s)
- Horst-Werner Korf
- Dr. Senckenbergische Anatomie, Institut für Anatomie II, Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
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13
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Milesi S, Simonneaux V, Klosen P. Downregulation of Deiodinase 3 is the earliest event in photoperiodic and photorefractory activation of the gonadotropic axis in seasonal hamsters. Sci Rep 2017; 7:17739. [PMID: 29255151 PMCID: PMC5735130 DOI: 10.1038/s41598-017-17920-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 12/04/2017] [Indexed: 02/06/2023] Open
Abstract
In seasonal rodents, reproduction is activated by a long photoperiod. Furthermore, maintaining an inhibitory short photoperiod for over 20 weeks triggers a spontaneous reactivation of the gonadotropic axis called photorefractoriness. Photoactivation is proposed to involve melatonin, hypothalamic thyroid hormones (TH) and (Arg) (Phe)-amide peptides. The mechanisms involved in photorefractoriness are so far unknown. We analyzed the dynamic changes in long photoperiod- and photorefractory-induced activation of reproduction in both Syrian and Djungarian hamsters to validate the current model of photoactivation and to uncover the mechanisms involved in photorefractoriness. We detected a conserved early inhibition of expression of the TH catabolizing enzyme deiodinase 3 (Dio3) in tanycytes, associated with a late decrease of the TH transporter MCT8. This suggests that an early peak of hypothalamic TH may be involved in both photoinduced and photorefractory reactivation. In photoactivation, Dio3 downregulation is followed by an upregulation of Dio2, which is not observed in photorefraction. The upregulation of (Arg) (Phe)-amides occurs several weeks after the initial Dio3 inhibition. In conclusion, we uncovered a so far unreported early inhibition of Dio3. This early downregulation of Dio3 is reinforced by an upregulation of Dio2 in photoactivated hamsters. In photorefractoriness, the Dio3 downregulation might be sufficient to reactivate the gonadotropic axis.
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Affiliation(s)
- Sébastien Milesi
- Institute of Cellular and Integrative Neuroscience, CNRS, University of Strasbourg, 67084, Strasbourg, Cedex, France
| | - Valérie Simonneaux
- Institute of Cellular and Integrative Neuroscience, CNRS, University of Strasbourg, 67084, Strasbourg, Cedex, France.
| | - Paul Klosen
- Institute of Cellular and Integrative Neuroscience, CNRS, University of Strasbourg, 67084, Strasbourg, Cedex, France.
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Vriend J, Liu W, Reiter RJ. The pineal gland: A model for adrenergic modulation of ubiquitin ligases. PLoS One 2017; 12:e0172441. [PMID: 28212404 PMCID: PMC5315301 DOI: 10.1371/journal.pone.0172441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/04/2017] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION A recent study of the pineal gland of the rat found that the expression of more than 3000 genes showed significant day/night variations (The Hartley dataset). The investigators of this report made available a supplemental table in which they tabulated the expression of many genes that they did not discuss, including those coding for components of the ubiquitin proteasome system. Herein we identify the genes of the ubiquitin proteasome system whose expression were significantly influenced by environmental lighting in the Hartley dataset, those that were stimulated by DBcAMP in pineal glands in culture, and those that were stimulated by norepinephrine. PURPOSE Using the Ubiquitin and Ubiquitin-like Conjugation Database (UUCA) we identified ubiquitin ligases and conjugases, and deubiquitinases in the Hartley dataset for the purpose of determining whether expression of genes of the ubiquitin proteasome pathway were significantly influenced by day/night variations and if these variations were regulated by autonomic innervation of the pineal gland from the superior cervical ganglia. METHODS In the Hartley experiments pineal glands groups of rats sacrificed during the day and groups sacrificed during the night were examined for gene expression. Additional groups of rats had their superior cervical ganglia removed surgically or surgically decentralized and the pineal glands likewise examined for gene expression. RESULTS The genes with at least a 2-fold day/night significant difference in expression included genes for 5 ubiquitin conjugating enzymes, genes for 58 ubiquitin E3 ligases and genes for 6 deubiquitinases. A 35-fold day/night difference was noted in the expression of the gene Sik1, which codes for a protein containing both an ubiquitin binding domain (UBD) and an ubiquitin-associated (UBA) domain. Most of the significant differences in these genes were prevented by surgical removal, or disconnection, of the superior cervical ganglia, and most were responsive, in vitro, to treatment with a cyclic AMP analog, and norepinephrine. All previously described 24-hour rhythms in the pineal require an intact sympathetic input from the superior cervical ganglia. CONCLUSIONS The Hartley dataset thus provides evidence that the pineal gland is a highly useful model for studying adrenergically dependent mechanisms regulating variations in ubiquitin ligases, ubiquitin conjugases, and deubiquitinases, mechanisms that may be physiologically relevant not only in the pineal gland, but in all adrenergically innervated tissue.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Wenjun Liu
- Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, Texas, United States of America
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Chi L, Li X, Liu Q, Liu Y. Photoperiod regulate gonad development via kisspeptin/kissr in hypothalamus and saccus vasculosus of Atlantic salmon (Salmo salar). PLoS One 2017; 12:e0169569. [PMID: 28199332 PMCID: PMC5310791 DOI: 10.1371/journal.pone.0169569] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 12/19/2016] [Indexed: 12/19/2022] Open
Abstract
Atlantic salmon exhibit seasonal reproduction. However, the mechanisms governing this are still unclear. Generally speaking, kisspeptin has been recognized as a regulator of reproduction. Here, we report a relationship between kisspeptin, GnRH and photoperiod in Atlantic salmon. The results demonstrated that the expression of the Atlantic salmon kisspeptin-receptor (skissr) was not always consistent with the expression pattern of Atlantic salmon GnRH3 (sGnRH3) during all developmental processes. Kisspeptin may exert its influence primarily in the early and later stages of gonad development by promoting the secretion of sGnRH3. Meanwhile, the expression levels of kissr were higher in fish with gonads at stage II and stage V under the long-day photoperiod regime than under the short-day regime. In addition, both skissr and sGnRH3 were also expressed in the saccus vasculosus (SV), an organ only found in fish. The SV might be a seasonal sensor regulating reproduction in addition to the hypothalamus (Hyp).
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Affiliation(s)
- Liang Chi
- Center of Biotechnology R&D, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, P.R. China
- College of Animal Science and Technology, Qingdao Agricultural University, Qingdao, P.R. China
| | - Xian Li
- Center of Biotechnology R&D, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, P.R. China
- National & Local Joint Engineering Laboratory of Ecological Mari culture, Qingdao, China
| | - Qinghua Liu
- Center of Biotechnology R&D, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, P.R. China
| | - Ying Liu
- Center of Biotechnology R&D, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, P.R. China
- National & Local Joint Engineering Laboratory of Ecological Mari culture, Qingdao, China
- * E-mail:
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Henningsen JB, Gauer F, Simonneaux V. RFRP Neurons - The Doorway to Understanding Seasonal Reproduction in Mammals. Front Endocrinol (Lausanne) 2016; 7:36. [PMID: 27199893 PMCID: PMC4853402 DOI: 10.3389/fendo.2016.00036] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023] Open
Abstract
Seasonal control of reproduction is critical for the perpetuation of species living in temperate zones that display major changes in climatic environment and availability of food resources. In mammals, seasonal cues are mainly provided by the annual change in the 24-h light/dark ratio (i.e., photoperiod), which is translated into the nocturnal production of the pineal hormone melatonin. The annual rhythm in this melatonin signal acts as a synchronizer ensuring that breeding occurs when environmental conditions favor survival of the offspring. Although specific mechanisms might vary among seasonal species, the hypothalamic RF (Arg-Phe) amide-related peptides (RFRP-1 and -3) are believed to play a critical role in the central control of seasonal reproduction and in all seasonal species investigated, the RFRP system is persistently inhibited in short photoperiod. Central chronic administration of RFRP-3 in short day-adapted male Syrian hamsters fully reactivates the reproductive axis despite photoinhibitory conditions, which highlights the importance of the seasonal changes in RFRP expression for proper regulation of the reproductive axis. The acute effects of RFRP peptides, however, depend on species and photoperiod, and recent studies point toward a different role of RFRP in regulating female reproductive activity. In this review, we summarize the recent advances made to understand the role and underlying mechanisms of RFRP in the seasonal control of reproduction, primarily focusing on mammalian species.
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Affiliation(s)
- Jo B. Henningsen
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
| | - François Gauer
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
- *Correspondence: Valérie Simonneaux,
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17
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Weems PW, Goodman RL, Lehman MN. Neural mechanisms controlling seasonal reproduction: principles derived from the sheep model and its comparison with hamsters. Front Neuroendocrinol 2015; 37:43-51. [PMID: 25582913 PMCID: PMC4405450 DOI: 10.1016/j.yfrne.2014.12.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/05/2014] [Accepted: 12/07/2014] [Indexed: 10/24/2022]
Abstract
Seasonal reproduction is a common adaptive strategy among mammals that allows for breeding to occur at times of the year when it is most advantageous for the subsequent survival and growth of offspring. A major mechanism responsible for seasonal reproduction is a striking increase in the responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the negative feedback effects of estradiol. The neural and neuroendocrine circuitry responsible for mammalian seasonal reproduction has been primarily studied in three animal models: the sheep, and two species of hamsters. In this review, we first describe the afferent signals, neural circuitry and transmitters/peptides responsible for seasonal reproductive transitions in sheep, and then compare these mechanisms with those derived from studies in hamsters. The results suggest common principles as well as differences in the role of specific brain nuclei and neuropeptides, including that of kisspeptin cells of the hypothalamic arcuate nucleus, in regulating seasonal reproduction among mammals.
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Affiliation(s)
- Peyton W Weems
- Program in Neuroscience, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216, USA; Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39232, USA
| | - Robert L Goodman
- Department of Physiology & Pharmacology, West Virginia University, PO Box 6201, Morgantown, WV 26506, USA
| | - Michael N Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39232, USA.
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18
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Stevenson TJ, Prendergast BJ. Photoperiodic time measurement and seasonal immunological plasticity. Front Neuroendocrinol 2015; 37:76-88. [PMID: 25456046 PMCID: PMC4405432 DOI: 10.1016/j.yfrne.2014.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/04/2014] [Accepted: 10/09/2014] [Indexed: 12/16/2022]
Abstract
Seasonal variations in immunity are common in nature, and changes in day length are sufficient to trigger enhancement and suppression of immune function in many vertebrates. Drawing primarily on data from Siberian hamsters, this review describes formal and physiological aspects of the neuroendocrine regulation of seasonal changes in mammalian immunity. Photoperiod regulates immunity in a trait-specific manner, and seasonal changes in gonadal hormone secretion and thyroid hormone signaling all participate in seasonal immunomodulation. Photoperiod-driven changes in the hamster reproductive and immune systems are associated with changes in iodothyronine deiodinase-mediated thyroid hormone signaling, but photoperiod exerts opposite effects on select aspects of the epigenetic regulation of reproductive neuroendocrine and lymphoid tissues. Photoperiodic changes in immunocompetence may explain a proportion of the annual variance in disease incidence and severity in nature, and provide a useful framework to help understand brain-immune interactions.
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Affiliation(s)
- Tyler J Stevenson
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
| | - Brian J Prendergast
- Department of Psychology and Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, USA
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19
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Vriend J, Reiter RJ. Melatonin and ubiquitin: what's the connection? Cell Mol Life Sci 2014; 71:3409-18. [PMID: 24920061 PMCID: PMC11113875 DOI: 10.1007/s00018-014-1659-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/09/2014] [Accepted: 05/27/2014] [Indexed: 12/29/2022]
Abstract
Melatonin has been widely studied for its role in photoperiodism in seasonal breeders; it is also a potent antioxidant. Ubiquitin, a protein also widespread in living cells, contributes to many cellular events, although the most well known is that of tagging proteins for destruction by the proteasome. Herein, we suggest a model in which melatonin interacts with the ubiquitin-proteasome system to regulate a variety of seemingly unrelated processes. Ubiquitin, for example, is a major regulator of central activity of thyroid hormone type 2 deiodinase; the subsequent regulation of T3 may be central to the melatonin-induced changes in seasonal reproduction and seasonal changes in metabolism. Both melatonin and ubiquitin also have important roles in protecting cells from oxidative stress. We discuss the interaction of melatonin and the ubiquitin-proteasome system in oxidative stress through regulation of the ubiquitin-activating enzyme, E1. Previous reports have shown that glutathiolation of this enzyme protects proteins from unnecessary degradation. In addition, evidence is discussed concerning the interaction of ubiquitin and melatonin in activation of the transcription factor NF-κB as well as modulating cellular levels of numerous signal transducing factors including the tumor suppressor, p53. Some of the actions of melatonin on the regulatory particle of the proteasome appear to be related to its inhibition of the calcium-dependent calmodulin kinase II, an enzyme which reportedly copurifies with proteasomes. Many of the actions of melatonin on signal transduction are similar to those of a proteasome inhibitor. While these actions of melatonin could be explained by a direct inhibitory action on the catalytic core particle of the proteasome, this has not been experimentally verified. If our hypothesis of melatonin as a general inhibitor of the ubiquitin-proteasome system is confirmed, it is predicted that more examples of this interaction will be demonstrated in a variety of tissues in which ubiquitin and melatonin co-exist. Furthermore, the hypothesis of melatonin as an inhibitor of the ubiquitin-proteasome system will be a very useful model for clinical testing of melatonin.
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Affiliation(s)
- Jerry Vriend
- Department of Human Anatomy and Cell Science, University of Manitoba, 745 Bannatyne Avenue, Winnipeg, MB, R3E 0J9, Canada,
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20
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Nakane Y, Yoshimura T. Universality and diversity in the signal transduction pathway that regulates seasonal reproduction in vertebrates. Front Neurosci 2014; 8:115. [PMID: 24959116 PMCID: PMC4033074 DOI: 10.3389/fnins.2014.00115] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 05/01/2014] [Indexed: 12/15/2022] Open
Abstract
Most vertebrates living outside the tropical zone show robust physiological responses in response
to seasonal changes in photoperiod, such as seasonal reproduction, molt, and migration. The highly
sophisticated photoperiodic mechanism in Japanese quail has been used to uncover the mechanism of
seasonal reproduction. Molecular analysis of quail mediobasal hypothalamus (MBH) revealed that local
thyroid hormone activation within the MBH plays a critical role in the photoperiodic response of
gonads. This activation is accomplished by two gene switches: thyroid hormone-activating (DIO2) and
thyroid hormone-inactivating enzymes (DIO3). Functional genomics studies have shown that long-day
induced thyroid-stimulating hormone (TSH) in the pars tuberalis (PT) of the pituitary gland
regulates DIO2/3 switching. In birds, light information received directly by deep brain
photoreceptors regulates PT TSH. Recent studies demonstrated that Opsin 5-positive cerebrospinal
fluid (CSF)-contacting neurons are deep brain photoreceptors that regulate avian seasonal
reproduction. Although the involvement of TSH and DIO2/3 in seasonal reproduction has been confirmed
in various mammals, the light input pathway that regulates PT TSH in mammals differs from that of
birds. In mammals, the eye is the only photoreceptor organ and light information received by the eye
is transmitted to the pineal gland through the circadian pacemaker, the suprachiasmatic nucleus.
Nocturnal melatonin secretion from the pineal gland indicates the length of night and regulates the
PT TSH. In fish, the regulatory machinery for seasonal reproduction, from light input to
neuroendocrine output, has been recently demonstrated in the coronet cells of the saccus vasculosus
(SV). The SV is unique to fish and coronet cells are CSF-contacting neurons. Here, we discuss the
universality and diversity of signal transduction pathways that regulate vertebrate seasonal
reproduction.
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Affiliation(s)
- Yusuke Nakane
- Laboratory of Animal Physiology, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University Nagoya, Japan
| | - Takashi Yoshimura
- Laboratory of Animal Physiology, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University Nagoya, Japan ; Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University Nagoya, Japan ; Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University Nagoya, Japan ; Division of Seasonal Biology, Department of Environmental Biology, National Institute for Basic Biology Okazaki, Japan
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Abstract
Most species living outside the tropical zone undergo physiological adaptations to
seasonal environmental changes and changing day length (photoperiod); this phenomenon is
called photoperiodism. It is well known that the circadian clock is involved in the
regulation of photoperiodism such as seasonal reproduction, but the mechanism underlying
circadian clock regulation of photoperiodism remains unclear. Recent molecular analysis
have revealed that, in mammals and birds, the pars tuberalis (PT) of the pituitary gland
acts as the relay point from light receptors, which receive information about the
photoperiod, to the endocrine responses. Long-day (LD)-induced thyroid-stimulating hormone
(TSH) in the PT acts as a master regulator of seasonal reproduction in the ependymal cells
(ECs) within the mediobasal hypothalamus (MBH) and activates thyroid hormone (TH) by
inducing the expression of type 2 deiodinase in both LD and short-day (SD) breeding
animals. Furthermore, the circadian clock has been found to be localized in the PT and ECs
as well as in the circadian pacemaker(s). This review purposes to summarize the current
knowledge concerning the involvement of the neuroendocrine system and circadian clock in
seasonal reproduction.
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Affiliation(s)
- Keisuke Ikegami
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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22
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Shinomiya A, Shimmura T, Nishiwaki-Ohkawa T, Yoshimura T. Regulation of seasonal reproduction by hypothalamic activation of thyroid hormone. Front Endocrinol (Lausanne) 2014; 5:12. [PMID: 24600435 PMCID: PMC3930870 DOI: 10.3389/fendo.2014.00012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 01/31/2014] [Indexed: 12/15/2022] Open
Abstract
Organisms living outside the tropics measure the changes in the length of the day to adapt to seasonal changes in the environment. Animals that breed during spring and summer are called long-day breeders, while those that breed during fall are called short-day breeders. Although the influence of thyroid hormone in the regulation of seasonal reproduction has been known for several decades, its precise mechanism remained unknown. Recent studies revealed that the activation of thyroid hormone within the mediobasal hypothalamus plays a key role in this phenomenon. This localized activation of the thyroid hormone is controlled by thyrotropin (thyroid-stimulating hormone) secreted from the pars tuberalis of the pituitary gland. Although seasonal reproduction is a rate-limiting factor in animal production, genes involved in photoperiodic signal transduction pathway could emerge as potential targets to facilitate domestication.
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Affiliation(s)
- Ai Shinomiya
- Division of Seasonal Biology, National Institute for Basic Biology, Okazaki, Japan
| | - Tsuyoshi Shimmura
- Division of Seasonal Biology, National Institute for Basic Biology, Okazaki, Japan
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Taeko Nishiwaki-Ohkawa
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Takashi Yoshimura
- Division of Seasonal Biology, National Institute for Basic Biology, Okazaki, Japan
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Japan
- Avian Bioscience Research Center, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Dardente H, Hazlerigg DG, Ebling FJP. Thyroid hormone and seasonal rhythmicity. Front Endocrinol (Lausanne) 2014; 5:19. [PMID: 24616714 PMCID: PMC3935485 DOI: 10.3389/fendo.2014.00019] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 02/10/2014] [Indexed: 12/15/2022] Open
Abstract
Living organisms show seasonality in a wide array of functions such as reproduction, fattening, hibernation, and migration. At temperate latitudes, changes in photoperiod maintain the alignment of annual rhythms with predictable changes in the environment. The appropriate physiological response to changing photoperiod in mammals requires retinal detection of light and pineal secretion of melatonin, but extraretinal detection of light occurs in birds. A common mechanism across all vertebrates is that these photoperiod-regulated systems alter hypothalamic thyroid hormone (TH) conversion. Here, we review the evidence that a circadian clock within the pars tuberalis of the adenohypophysis links photoperiod decoding to local changes of TH signaling within the medio-basal hypothalamus (MBH) through a conserved thyrotropin/deiodinase axis. We also focus on recent findings which indicate that, beyond the photoperiodic control of its conversion, TH might also be involved in longer-term timing processes of seasonal programs. Finally, we examine the potential implication of kisspeptin and RFRP3, two RF-amide peptides expressed within the MBH, in seasonal rhythmicity.
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Affiliation(s)
- Hugues Dardente
- Physiologie de la Reproduction et des Comportements, INRA, UMR085, Nouzilly, France
- CNRS, UMR7247, Nouzilly, France
- Université François Rabelais de Tours, Tours, France
- Institut français du cheval et de l’équitation, Nouzilly, France
- *Correspondence: Hugues Dardente, INRA, UMR85 Physiologie de la Reproduction et des Comportements, CNRS, UMR7247, Université François Rabelais de Tours, IFCE, F-37380 Nouzilly, France e-mail:
| | - David G. Hazlerigg
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
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The saccus vasculosus of fish is a sensor of seasonal changes in day length. Nat Commun 2013; 4:2108. [PMID: 23820554 DOI: 10.1038/ncomms3108] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 06/04/2013] [Indexed: 12/28/2022] Open
Abstract
The pars tuberalis of the pituitary gland is the regulatory hub for seasonal reproduction in birds and mammals. Although fish also exhibit robust seasonal responses, they do not possess an anatomically distinct pars tuberalis. Here we report that the saccus vasculosus of fish is a seasonal sensor. We observe expression of key genes regulating seasonal reproduction and rhodopsin family genes in the saccus vasculosus of masu salmon. Immunohistochemical studies demonstrate that all of these genes are expressed in the coronet cells of the saccus vasculosus, suggesting the existence of a photoperiodic signalling pathway from light input to neuroendocrine output. In addition, isolated saccus vasculosus has the capacity to respond to photoperiodic signals, and its removal abolishes photoperiodic response of the gonad. Although the physiological role of the saccus vasculosus has been a mystery for several centuries, our findings indicate that the saccus vasculosus acts as a sensor of seasonal changes in day length in fish.
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Kampf-Lassin A, Prendergast BJ. Acute downregulation of Type II and Type III iodothyronine deiodinases by photoperiod in peripubertal male and female Siberian hamsters. Gen Comp Endocrinol 2013; 193:72-8. [PMID: 23891658 PMCID: PMC3812426 DOI: 10.1016/j.ygcen.2013.07.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 07/15/2013] [Accepted: 07/18/2013] [Indexed: 10/26/2022]
Abstract
Availability of the thyroid hormone triiodothyronine (T3) in the mediobasal hypothalamus plays a central role in seasonal reproductive responses to photoperiod. Across many vertebrates, Type 2 iodothyronine deiodinase (DIO2) is elevated under reproductively stimulatory long days (LD) and synthesizes the conversion of thyroxine to T3; Type 3 iodothyronine deiodinase (DIO3) reduces T3 production and signaling, and is upregulated under reproductively-inhibitory short days (SD). In Siberian hamsters, regulation of hypothalamic T3 is dominated by dio3 expression, whereas dio2 expression is less-consistently affected by photoperiod. In adult hamsters, changes in deiodinase mRNA expression typically require several weeks to manifest, but it is not known whether or how quickly these mechanisms are engaged during the rapid responses to photoperiod observed in young, peri-pubertal hamsters. This experiment tested the hypotheses that (1) deiodinase responses to photoperiod are accelerated in juvenile hamsters and (2) photoperiodic downregulation of deiodinase expression occurs more rapidly than upregulation. Hypothalamic dio2 and dio3 mRNA expression was quantified in male and female Siberian hamsters that were weaned on postnatal day 18 (PND 18) into SD or remained in their natal LD, and on PND 31 were exposed to a single long or short day. In SD males and females, a single long day inhibited dio3 mRNA expression, but did not increase dio2 mRNA. In LD males, a single short day rapidly inhibited dio2 mRNA expression, but did not stimulate expression of dio3 mRNA. Downregulation of dio2 and dio3 mRNAs precedes gonadotrophin responses to day length. Rapid photoperiodic inhibition of deiodinase mRNAs may initiate changes in thyroid hormone signaling in advance of longer-term, melatonin-dependent, responses.
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Yoshimura T. Thyroid hormone and seasonal regulation of reproduction. Front Neuroendocrinol 2013; 34:157-66. [PMID: 23660390 DOI: 10.1016/j.yfrne.2013.04.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 04/21/2013] [Accepted: 04/23/2013] [Indexed: 12/15/2022]
Abstract
Organisms living outside the tropics use changes in photoperiod to adapt to seasonal changes in the environment. Several models have contributed to an understanding of this mechanism at the molecular and endocrine levels. Subtropical birds are excellent models for the study of these mechanisms because of their rapid and dramatic response to changes in photoperiod. Studies of birds have demonstrated that light is perceived by a deep brain photoreceptor and long day-induced thyrotropin (TSH) from the pars tuberalis (PT) of the pituitary gland causes local thyroid hormone activation within the mediobasal hypothalamus (MBH). The locally generated bioactive thyroid hormone, T₃, regulates seasonal gonadotropin-releasing hormone (GnRH) secretion, and hence gonadotropin secretion. In mammals, the eyes are the only photoreceptor involved in photoperiodic time perception and nocturnal melatonin secretion provides an endocrine signal of photoperiod to the PT to regulate TSH. Here, I review the current understanding of the hypothalamic mechanisms controlling seasonal reproduction in mammals and birds.
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Affiliation(s)
- Takashi Yoshimura
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
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Goto M, Matsuo H, Iigo M, Furuse M, Korf HW, Yasuo S. Melatonin-induced changes in the expression of thyroid hormone-converting enzymes in hypothalamus depend on the timing of melatonin injections and genetic background in mice. Gen Comp Endocrinol 2013; 186:33-40. [PMID: 23500007 DOI: 10.1016/j.ygcen.2013.02.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 02/01/2013] [Accepted: 02/24/2013] [Indexed: 11/21/2022]
Abstract
Recent studies have identified TSHB, Dio2, and Dio3 as key genes for the photoperiodic regulation of gonads. In mammals, the expression of these genes is controlled by melatonin. Surprisingly, this effect of melatonin was shown to be conserved in several reproductively non-photoperiodic laboratory mouse strains that have thus become a valuable model to decipher the mechanisms through which melatonin controls the expression of TSHB, Dio2, and Dio3. In this study, we assessed the effects of intraperitoneal melatonin injections and of their timing on the expression of TSHB, TSHR, Dio2, and Dio3 in the hypothalamo-hypophysial systems of melatonin-proficient CBA/N and melatonin-deficient C57BL/6J mice kept under long-day conditions. In CBA/N mice, Dio3 expression was induced by a daily melatonin injection at ZT14 only, whereas in C57BL/6J mice, a daily melatonin injection induced Dio3 expression at all time points investigated (ZT8, 14, and 20) without changes in TSHB expression in both strains. Dio2 expression was suppressed by a daily melatonin injection only in C57BL/6J mice and only at ZT8. Effect of a daily melatonin injection on TSHR expression was strain- and region- specific. Melatonin levels elevated in plasma and hypothalamus after intraperitoneal injections of melatonin at ZT8 for 7days in C57BL/6J returned to basal levels within 1h after the final injection, while in CBA/N mice melatonin levels in hypothalamus remained high for at least 1h. These data suggest that Dio2 and Dio3 expression in the hypothalamus is differentially regulated by the timing of melatonin injections through strain-specific mechanisms.
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Affiliation(s)
- Mariko Goto
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan
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Shalabi A, Fischer C, Korf HW, von Gall C. Melatonin-receptor-1-deficiency affects neurogenic differentiation factor immunoreaction in pancreatic islets and enteroendocrine cells of mice. Cell Tissue Res 2013; 353:483-91. [PMID: 23700151 DOI: 10.1007/s00441-013-1647-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 04/24/2013] [Indexed: 10/26/2022]
Abstract
Neurogenic differentiation factor (NeuroD) is a transcription factor involved in the differentiation of neurons and in the control of energy balance and metabolism. It plays a key role in type 1 and type 2 diabetes. Melatonin is an important rhythmic endocrine signal within the circadian system of mammals and modulates insulin secretion and glucose metabolism. In the mouse pars tuberalis, NeuroD mRNA levels show day/night variation, which is independent of the molecular clock gene mPER1 but depends on the functional melatonin receptor 1 (MT1). So far, little is known about the effect of melatonin on NeuroD synthesis in the gastrointestinal tract. Thus, NeuroD protein levels and cellular localization were analyzed by immunohistochemistry in pancreatic islets and duodenal enteroendocrine cells of MT1- and mPER1-deficienct mice. In addition, the localization of NeuroD-positive cells was analyzed by double-immunofluorescence and confocal laser microscopy. In duodenal enteroendocrine cells and pancreatic islets of WT and PER1-deficient mice, NeuroD immunoreaction showed a peak during the early subjective night. In contrast, this peak was absent in MT1-deficent mice. These data suggest that melatonin, by acting on MT1 receptors, affects NeuroD expression in the gastrointestinal tract and thus might contribute to circadian regulation in metabolic functions.
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Affiliation(s)
- Andree Shalabi
- Dr. Senckenbergische Anatomie, Institut für Anatomie II, Johann-Wolfgang-Goethe-Universität, Theodor-Stern-Kai 7, 60590, Frankfurt/M, Germany
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Klosen P, Sébert M, Rasri K, Laran‐Chich M, Simonneaux V. TSH restores a summer phenotype in photoinhibited mammals
via
the RF‐amides RFRP3 and kisspeptin. FASEB J 2013; 27:2677-86. [DOI: 10.1096/fj.13-229559] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Paul Klosen
- Département de Neurobiologie des RythmesInstitut des Neurosciences Cellulaires et IntégrativesCentre National de la Recherche Scientifique (CNRS) Unité Propres de Recherche (UPR) 3212Université de StrasbourgStrasbourgFrance
| | - Marie‐Emilie Sébert
- Département de Neurobiologie des RythmesInstitut des Neurosciences Cellulaires et IntégrativesCentre National de la Recherche Scientifique (CNRS) Unité Propres de Recherche (UPR) 3212Université de StrasbourgStrasbourgFrance
| | - Kamontip Rasri
- Department of Pre‐Clinical ScienceFaculty of MedicineThammasart UniversityRangsitThailand
| | - Marie‐Pierre Laran‐Chich
- Département de Neurobiologie des RythmesInstitut des Neurosciences Cellulaires et IntégrativesCentre National de la Recherche Scientifique (CNRS) Unité Propres de Recherche (UPR) 3212Université de StrasbourgStrasbourgFrance
| | - Valérie Simonneaux
- Département de Neurobiologie des RythmesInstitut des Neurosciences Cellulaires et IntégrativesCentre National de la Recherche Scientifique (CNRS) Unité Propres de Recherche (UPR) 3212Université de StrasbourgStrasbourgFrance
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Prendergast BJ, Pyter LM, Kampf-Lassin A, Patel PN, Stevenson TJ. Rapid induction of hypothalamic iodothyronine deiodinase expression by photoperiod and melatonin in juvenile Siberian hamsters (Phodopus sungorus). Endocrinology 2013; 154:831-41. [PMID: 23295738 PMCID: PMC3548179 DOI: 10.1210/en.2012-1990] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Production of T(3) in the mediobasal hypothalamus is critical for regulation of seasonal reproductive physiology. Type 2 iodothyronine deiodinase (DIO2) and DIO3 enzymes catalyze the prohormone T(4) into biologically-active T(3) and biologically-inactive rT(3), respectively. In several seasonally-breeding vertebrates, DIO2 and DIO3 expression is implicated in photoperiod signal transduction in adulthood. These experiments tested the hypothesis that juvenile Siberian hamsters, which are highly responsive to photoperiod at weaning (postnatal day [PND]18), exhibit rapid and sustained changes in hypothalamic dio3 mRNA expression during photoperiod-induced and photoperiod-inhibited puberty. Hypothalamic dio2 and dio3 expression was measured via quantitative PCR in hamsters born and reared in a long-day photoperiod (15L:9D) and weaned on PND18 into short-day photoperiods (9L:15D). In SD males, hypothalamic dio3 mRNA was elevated 2.5-fold within 3 days (PND21) and continued to increase (>20-fold) through PND32; changes in dio3 mRNA preceded inhibition of gonadotropin (FSH) secretion and gonadal regression in SD. Females exhibited comparable dio3 responses to SD. In LD males, dio3 remained low and invariant from PND18-PND32. In contrast, dio2 mRNA rose conspicuously on PND21, independent of photoperiod, returning to basal levels thereafter. In LD, a single afternoon melatonin (MEL) injection on PND18 or PND20 was sufficient to increase hypothalamic dio3 mRNA, and dio3 increased in proportion to the number of successive days of MEL treatment. SD photoperiods and MEL exert rapid, sustained, and additive effects on hypothalamic dio3 mRNA, which may play a central role in inhibiting maturation of the peripubertal hypothalamo-pituitary-gonadal axis.
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Bolborea M, Dale N. Hypothalamic tanycytes: potential roles in the control of feeding and energy balance. Trends Neurosci 2013; 36:91-100. [PMID: 23332797 PMCID: PMC3605593 DOI: 10.1016/j.tins.2012.12.008] [Citation(s) in RCA: 210] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 12/11/2012] [Accepted: 12/18/2012] [Indexed: 02/08/2023]
Abstract
Tanycytes, glial-like cells that line the third ventricle, are emerging as components of the hypothalamic networks that control body weight and energy balance. They contact the cerebrospinal fluid (CSF) and send processes that come into close contact with neurons in the arcuate and ventromedial hypothalamic nuclei. Tanycytes are glucosensitive and are able to respond to transmitters associated with arousal and the drive to feed. At least some tanycytes are stem cells and, in the median eminence, may be stimulated by diet to generate new neurons. The quest is on to understand how tanycytes detect and respond to changes in energy balance and how they communicate with the rest of the nervous system to effect their functions.
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Affiliation(s)
- Matei Bolborea
- School of Life Sciences, University of Warwick, Coventry, UK
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32
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Orozco A, Valverde-R C, Olvera A, García-G C. Iodothyronine deiodinases: a functional and evolutionary perspective. J Endocrinol 2012; 215:207-19. [PMID: 22872760 DOI: 10.1530/joe-12-0258] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
From an evolutionary perspective, deiodinases may be considered pivotal players in the emergence and functional diversification of both thyroidal systems (TS) and their iodinated messengers. To better understand the evolutionary pathway and the concomitant functional diversification of vertebrate deiodinases, in the present review we summarized the highlights of the available information regarding this ubiquitous enzymatic component that represents the final, common physiological link of TS. The information reviewed here suggests that deiodination of tyrosine metabolites is an ancient feature of all chordates studied to date and consequently, that it precedes the integration of the TS that characterize vertebrates. Phylogenetic analysis presented here points to D1 as the oldest vertebrate deiodinase and to D2 as the most recent deiodinase gene, a hypothesis that agrees with the notion that D2 is the most specialized and finely regulated member of the family and plays a key role in vertebrate neurogenesis. Thus, deiodinases seem to be major participants in the evolution and functional expansion of the complex regulatory network of TS found in vertebrates.
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Affiliation(s)
- Aurea Orozco
- Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla, Juriquilla, Querétaro, México.
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33
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Analysis on DNA sequence of TSHB gene and its association with reproductive seasonality in goats. Mol Biol Rep 2012; 40:1893-904. [PMID: 23076536 DOI: 10.1007/s11033-012-2245-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 10/10/2012] [Indexed: 12/15/2022]
Abstract
Thyroid stimulating hormone beta chain (TSHB) is mainly expressed in pituitary and its expression is closely related to photoperiodic control of seasonal reproduction in animals. In the present study, ten primer pairs have been used to clone the DNA sequence and to detect genetic mutations of goat TSHB gene. Two DNA fragments of goat TSHB gene were obtained, which were 2,614 and 1,031 bp in length, respectively. They comprised about 2.5 kb 5' regulatory region, all of the three exons and two introns. Goat TSHB gene has a coding region of 417 bp, encoding 138 amino acids which was predicted to be a secretory protein with a signal peptide of 16 amino acids. The sequence of TSHB gene is highly conserved among mammals. In addition, five mutations (C53A, 3 bp Indel at the 287-289 locus, 34 bp Indel at the 584-617 locus, A1819C and E2_72TA) were found in goat TSHB gene and they were shown to be in strong linkage disequilibrium. Interestingly, the genotype distributions for both single locus and haplotype have shown to be significant different between seasonal and nonseasonal goat breeds. And haplotype H2 and diplotype H2/H4 may be related to year-round estrus. We preliminarily presumed that the five closely linked mutations of goat TSHB gene may be part of the causal sources for the diversities of reproductive seasonality in goats. Our study may provide a possible efficient genetic way to decrease seasonality in goats.
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[The neuroendocrine regulatory mechanisms of mammalian seasonal reproduction]. YI CHUAN = HEREDITAS 2012; 34:281-8. [PMID: 22425946 DOI: 10.3724/sp.j.1005.2012.00281] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The seasonal reproduction of mammal means the reproduction experiences an annual period from quiescence to renaissance. Studies have shown that kisspeptin and RFRP play an important role in the reproductive seasonality. The non-breeding season is characterized by an increase in the negative feedback effect of estrogen on GnRH, and this effect is transmitted by kisspeptin neurons, which may be an important factor affecting the reproduction activities. The expression of RFRP depends on melatonin secretion, and shows an apparent inhibition on reproduction in non-breeding season. In addition, thyroid hormones influence termination of the breeding season. Dopaminergic neuron A14/A15 also contributes to the seasonal changes in estrogen negative feedback. These neural systems may synergistically modulate the seasonal changes of reproductive function with the photoperiod. This review makes a systematic expatiation on the relationship between seasonal reproduction and these neural systems.
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35
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Ikegami K, Yoshimura T. Circadian clocks and the measurement of daylength in seasonal reproduction. Mol Cell Endocrinol 2012; 349:76-81. [PMID: 21767603 DOI: 10.1016/j.mce.2011.06.040] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/18/2011] [Accepted: 06/28/2011] [Indexed: 12/15/2022]
Abstract
Temperate zone organisms measure changes in daylength to adapt to seasonal changes in their environment. Recent studies have revealed that the long day (LD)-induced thyrotropin (TSH) in the pars tuberalis (PT) of the pituitary gland act as a master factor regulating seasonal reproduction on the the ependymal cells (ECs) within the mediobasal hypothalamus (MBH) to induce expression of type 2 deiodinase (Dio2), a thyroid hormone (TH)-activating enzyme in both LD and short day (SD) breeders. Locally activated TH in the MBH is believed to trigger GnRH secretion from the hypothalamus in LD breeders, while it terminates reproductive activity in SD breeders. Circadian clock is involved in seasonal time measurement and clock genes are expressed in the PT and ECs. Although circadian and melatonin-dependent control of TSH appears to link the circadian clock and the photoperiodic response in mammals, how this circadian clock measure daylength remains to be clarified.
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Affiliation(s)
- Keisuke Ikegami
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
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36
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Christ E, Korf HW, von Gall C. When does it start ticking? Ontogenetic development of the mammalian circadian system. PROGRESS IN BRAIN RESEARCH 2012; 199:105-118. [PMID: 22877661 DOI: 10.1016/b978-0-444-59427-3.00006-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Circadian rhythms in physiology and behavior ensure that vital functions are temporally synchronized with cyclic environmental changes. In mammals, the circadian system is conducted by a central circadian rhythm generator that resides in the hypothalamic suprachiasmatic nucleus (SCN) and controls multiple subsidiary circadian oscillators in the periphery. The molecular clockwork in SCN and peripheral oscillators consists of autoregulatory transcriptional/translational feedback loops of clock genes. The adult circadian system is synchronized to the astrophysical day by light whereas the fetal and neonatal circadian system entrains to nonphotic rhythmic maternal signals. This chapter reviews maturation and entrainment of the central circadian rhythm generator in the SCN and of peripheral oscillators during ontogenetic development.
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Affiliation(s)
- Elmar Christ
- Dr. Senckenbergische Anatomie II, Fachbereich Medizin, Goethe-Universität Frankfurt, Frankfurt am Main, Germany.
| | - Horst-Werner Korf
- Dr. Senckenbergische Anatomie II, Fachbereich Medizin, Goethe-Universität Frankfurt, Frankfurt am Main, Germany; Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
| | - Charlotte von Gall
- Dr. Senckenbergische Anatomie II, Fachbereich Medizin, Goethe-Universität Frankfurt, Frankfurt am Main, Germany; Dr. Senckenbergisches Chronomedizinisches Institut, Goethe-Universität Frankfurt, Frankfurt am Main, Germany
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Wambiji N, Park YJ, Kim SJ, Hur SP, Takeuchi Y, Takemura A. Expression of type II iodothyronine deiodinase gene in the brain of a tropical spinefoot, Siganus guttatus. Comp Biochem Physiol A Mol Integr Physiol 2011; 160:447-52. [DOI: 10.1016/j.cbpa.2011.03.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Revised: 03/28/2011] [Accepted: 03/28/2011] [Indexed: 11/15/2022]
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Bedolla DE, Torre V. A component of retinal light adaptation mediated by the thyroid hormone cascade. PLoS One 2011; 6:e26334. [PMID: 22039463 PMCID: PMC3200322 DOI: 10.1371/journal.pone.0026334] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 09/25/2011] [Indexed: 11/18/2022] Open
Abstract
Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2-3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4-8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation.
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Affiliation(s)
- Diana E. Bedolla
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Vincent Torre
- Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy
- Italian Institute of Technology (IIT), SISSA-Unit, Trieste, Italy
- * E-mail:
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39
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Bolborea M, Laran-Chich MP, Rasri K, Hildebrandt H, Govitrapong P, Simonneaux V, Pévet P, Steinlechner S, Klosen P. Melatonin controls photoperiodic changes in tanycyte vimentin and neural cell adhesion molecule expression in the Djungarian hamster (Phodopus sungorus). Endocrinology 2011; 152:3871-83. [PMID: 21846800 DOI: 10.1210/en.2011-1039] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The Djungarian hamster displays photoperiodic variations in gonadal size synchronized to the seasons by the nightly secretion of the pineal hormone melatonin. In short photoperiod (SP), the gonads regress in size, and circulating sex steroids levels decline. Thus, the brain is subject to seasonal variations of both melatonin and sex steroids. Tanycytes are specialized glial cells located in the ependymal lining of the third ventricle. They send processes either to the meninges or to blood vessels of the medio-basal hypothalamus. Furthermore, they are known to locally modulate GnRH release in the median eminence and to display seasonal structural changes. Seasonal changes in tanycyte morphology might be mediated either through melatonin or sex steroids. Therefore, we analyzed the effects of photoperiod, melatonin, and sex steroids 1) on tanycyte vimentin expression by immunohistochemistry and 2) on the expression of the neural cell adhesion molecule (NCAM) and polysialic acid as markers of brain plasticity. Vimentin immunostaining was reduced in tanycyte cell bodies and processes in SP. Similarly, tanycytes and their processes contained lower amounts of NCAM in SP. These changes induced by SP exposure could not be restored to long photoperiod (LP) levels by testosterone supplementation. Likewise, castration in LP did not affect tanycyte vimentin or NCAM expression. By contrast, late afternoon melatonin injections mimicking a SP-like melatonin peak in LP hamsters reduced vimentin and NCAM expression. Thus, the seasonal changes in vimentin and NCAM expression in tanycytes are regulated by melatonin independently of seasonal sex steroid changes.
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Affiliation(s)
- Matei Bolborea
- Tierärztliche Hochschule, Institut für Zoologie, 30559 Hannover, Germany
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40
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Research progress in molecular mechanism of animal seasonal reproduction. YI CHUAN = HEREDITAS 2011; 33:695-706. [DOI: 10.3724/sp.j.1005.2011.00695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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41
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Walton JC, Weil ZM, Nelson RJ. Influence of photoperiod on hormones, behavior, and immune function. Front Neuroendocrinol 2011; 32:303-19. [PMID: 21156187 PMCID: PMC3139743 DOI: 10.1016/j.yfrne.2010.12.003] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 11/30/2010] [Accepted: 12/03/2010] [Indexed: 01/26/2023]
Abstract
Photoperiodism is the ability of plants and animals to measure environmental day length to ascertain time of year. Central to the evolution of photoperiodism in animals is the adaptive distribution of energetically challenging activities across the year to optimize reproductive fitness while balancing the energetic tradeoffs necessary for seasonally-appropriate survival strategies. The ability to accurately predict future events requires endogenous mechanisms to permit physiological anticipation of annual conditions. Day length provides a virtually noise free environmental signal to monitor and accurately predict time of the year. In mammals, melatonin provides the hormonal signal transducing day length. Duration of pineal melatonin is inversely related to day length and its secretion drives enduring changes in many physiological systems, including the HPA, HPG, and brain-gut axes, the autonomic nervous system, and the immune system. Thus, melatonin is the fulcrum mediating redistribution of energetic investment among physiological processes to maximize fitness and survival.
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Affiliation(s)
- James C Walton
- Department of Neuroscience, The Ohio State University Medical Center, Columbus, OH 43210, USA.
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Thyroid hormone signalling genes are regulated by photoperiod in the hypothalamus of F344 rats. PLoS One 2011; 6:e21351. [PMID: 21731713 PMCID: PMC3120865 DOI: 10.1371/journal.pone.0021351] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 05/26/2011] [Indexed: 11/19/2022] Open
Abstract
Seasonal animals adapt their physiology and behaviour in anticipation of climate change to optimise survival of their offspring. Intra-hypothalamic thyroid hormone signalling plays an important role in seasonal responses in mammals and birds. In the F344 rat, photoperiod stimulates profound changes in food intake, body weight and reproductive status. Previous investigations of the F344 rat have suggested a role for thyroid hormone metabolism, but have only considered Dio2 expression, which was elevated in long day photoperiods. Microarray analysis was used to identify time-dependent changes in photoperiod responsive genes, which may underlie the photoperiod-dependent phenotypes of the juvenile F344 rat. The most significant changes are those related to thyroid hormone metabolism and transport. Using photoperiod manipulations and melatonin injections into long day photoperiod (LD) rats to mimic short day (SD), we show photoinduction and photosuppression gene expression profiles and melatonin responsiveness of genes by in situ hybridization; TSHβ, CGA, Dio2 and Oatp1c1 genes were all elevated in LD whilst in SD, Dio3 and MCT-8 mRNA were increased. NPY was elevated in SD whilst GALP increased in LD. The photoinduction and photosuppression profiles for GALP were compared to that of GHRH with GALP expression following GHRH temporally. We also reveal gene sets involved in photoperiodic responses, including retinoic acid and Wnt/ß-catenin signalling. This study extends our knowledge of hypothalamic regulation by photoperiod, by revealing large temporal changes in expression of thyroid hormone signalling genes following photoperiod switch. Surprisingly, large changes in hypothalamic thyroid hormone levels or TRH expression were not detected. Expression of NPY and GALP, two genes known to regulate GHRH, were also changed by photoperiod. Whether these genes could provide links between thyroid hormone signalling and the regulation of the growth axis remains to be investigated.
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43
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Yasuo S, Korf HW. The hypophysial pars tuberalis transduces photoperiodic signals via multiple pathways and messenger molecules. Gen Comp Endocrinol 2011; 172:15-22. [PMID: 21078321 DOI: 10.1016/j.ygcen.2010.11.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2010] [Accepted: 11/08/2010] [Indexed: 11/26/2022]
Abstract
Located between the median eminence, the portal vessels, and the pars distalis (PD) of the hypophysis, the hypophysial pars tuberalis (PT) is an important center for transmission of photoperiodic information to neuroendocrine circuits involved in the control of reproduction, metabolism and behavior. Despite enormous and long lasting efforts, output pathways and messenger molecules from the PT have been unraveled only recently. Most interestingly, the PT sends its signals in two directions: via a "retrograde" pathway to the hypothalamus and via an "anterograde" pathway to the PD. TSH has been identified as a messenger of the "retrograde" pathway. As discovered in Japanese quail, TSH triggers molecular cascades mediating thyroid hormone conversion in the mediobasal hypothalamus (MBH) to activate the gonadal axis. These molecular mechanisms are conserved in photoperiodic mammals, and even in non-photoperiodic laboratory mice. The search for molecules of the "anterograde" pathway was for a long time focused on PT-specific neuropeptides, the so-called "tuberalins". The discovery of a PT-intrinsic endocannabinoid system in hamsters which is regulated by the photoperiod provides strong experimental evidence that the PT also synthesizes lipidergic messengers. To date, 2-arachidonoylglycerol (2-AG) appears as the most important lipidergic messenger from the PT. The primary target of 2-AG, the cannabinoid receptor 1 (CB1) is expressed in the hamster PD. A PT-intrinsic endocannabinoid system also exists in man and CB1 receptors are demonstrated in ACTH-producing cells and folliculo-stellate cells of the human PD. These data lend support to the hypothesis that endocannabinoids function as messengers of the anterograde pathway.
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Affiliation(s)
- Shinobu Yasuo
- Dr. Senckenbergische Anatomie, Institut für Anatomie II, Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
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Abstract
In temperate zones, animals use changes in day length as a calendar to time their breeding season. However, the photoreceptive and neuroendocrine mechanisms of seasonal reproduction are considered to differ markedly between birds and mammals. This can be understood from the fact that the eye is the only photoreceptive organ, and melatonin mediates the photoperiodic information in mammals, whereas in birds, photoperiodic information is directly received by the deep brain photoreceptors and melatonin is not involved in seasonal reproduction. Recent molecular and functional genomics analysis uncovered the gene cascade regulating seasonal reproduction in birds and mammals. Long day-induced thyroid stimulating hormone in the pars tuberalis of the pituitary gland regulates thyroid hormone catabolism within the mediobasal hypothalamus. Further, this local thyroid hormone catabolism appears to regulate seasonal gonadotropin-releasing hormone secretion. These findings suggest that although the light input pathway is different between birds and mammals (i.e. light or melatonin), the core mechanisms are conserved in these vertebrates.
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Affiliation(s)
- Takashi Yoshimura
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan.
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Skipor J, Misztal T, Kaczmarek MM. Independent changes of thyroid hormones in blood plasma and cerebrospinal fluid after melatonin treatment in ewes. Theriogenology 2010; 74:236-45. [PMID: 20452012 DOI: 10.1016/j.theriogenology.2010.02.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 02/05/2010] [Accepted: 02/05/2010] [Indexed: 11/26/2022]
Abstract
The authors measured the effects of exogenous melatonin treatment on the concentrations of total (T) and free (f) fractions of thyroxine (T4) and triiodothyronine (T3) in cerebrospinal fluid (CSF) and blood plasma as well as the expression of their binding/transporter protein, transthyretin (TTR), in the choroid plexus of ewes from May to August. Melatonin implantation in May and July mainly prevented the decrease in plasma for fT3 and TT3 exhibited in untreated group, and induced a limited decrease in TT4 in June. By contrast, melatonin implantation prevented the decrease in CSF fT3 observed in the untreated group. No effect of melatonin was found on the expression of TTR mRNA in the choroid plexus There were a correlations between blood fT4 and CSF TT4 concentrations in both control and melatonin treated group (r(2)-0.4; P < 0.01 vs. r(2)-0.14; P < 0.05), as well as between blood fT3 and CSF TT3 concentrations but only in the melatonin-treated group (r(2)-0.26; P < 0.02). We conclude that T3, the active form of the hormone within the brain, is regulated by melatonin independently of the peripheral changes within the blood. The lack of correlation between plasma fT3 and CSF TT3 in the control group suggests that an increase in local T3 conversion could contribute as an additional source of T3 in the CSF during the period of increasing day length. These data seem to confirm a local nature for recently discovered connections between the pineal melatonin signal and thyroid-dependent seasonal biology in mammals.
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Affiliation(s)
- J Skipor
- Division of Reproductive Endocrinology and Pathophysiology, Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
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Prendergast BJ. MT1 melatonin receptors mediate somatic, behavioral, and reproductive neuroendocrine responses to photoperiod and melatonin in Siberian hamsters (Phodopus sungorus). Endocrinology 2010; 151:714-21. [PMID: 19966183 PMCID: PMC2817621 DOI: 10.1210/en.2009-0710] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Environmental day length drives nocturnal pineal melatonin secretion, which in turn generates or entrains seasonal cycles of physiology, reproduction, and behavior. In mammals, melatonin (MEL) binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery. The MEL receptors that mediate photoperiodic reproductive and behavioral responses to MEL have not been identified in a reproductively photoperiodic species. Here I tested the hypothesis that MT1 receptors are necessary and sufficient to engage photoperiodic responses by challenging male Siberian hamsters (Phodopus sungorus), a species that does not express functional MT2 receptors, with ramelteon (RAM), a specific MT1/MT2 receptor agonist. In hamsters housed in a long-day photoperiod, late-afternoon RAM treatment inhibited gonadotropin secretion, induced gonadal regression, and suppressed food intake and body mass, mimicking effects of MEL. In addition, chronic (24 h/d) RAM infusions were sufficient to obscure endogenous MEL signaling, and these treatments attenuated gonadal regression in short days. Together, the outcomes indicate that signaling at the MT1 receptor is sufficient and necessary to mediate the effects of photoperiod-driven changes in MEL on behavior and reproductive function in a reproductively photoperiodic mammal.
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Affiliation(s)
- Brian J Prendergast
- Department of Psychology and Committee on Neurobiology, Institute for Mind and Biology, University of Chicago, 940 East 57th Street, Chicago, Illinois 60637, USA.
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Migaud H, Davie A, Taylor JF. Current knowledge on the photoneuroendocrine regulation of reproduction in temperate fish species. JOURNAL OF FISH BIOLOGY 2010; 76:27-68. [PMID: 20738699 DOI: 10.1111/j.1095-8649.2009.02500.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Seasonality is an important adaptive trait in temperate fish species as it entrains or regulates most physiological events such as reproductive cycle, growth profile, locomotor activity and key life-stage transitions. Photoperiod is undoubtedly one of the most predictable environmental signals that can be used by most living organisms including fishes in temperate areas. This said, however, understanding of how such a simple signal can dictate the time of gonadal recruitment and spawning, for example, is a complex task. Over the past few decades, many scientists attempted to unravel the roots of photoperiodic signalling in teleosts by investigating the role of melatonin in reproduction, but without great success. In fact, the hormone melatonin is recognized as the biological time-keeping hormone in fishes mainly due to the fact that it reflects the seasonal variation in daylength across the whole animal kingdom rather than the existence of direct evidences of its role in the entrainment of reproduction in fishes. Recently, however, some new studies clearly suggested that melatonin interacts with the reproductive cascade at a number of key steps such as through the dopaminergic system in the brain or the synchronization of the final oocyte maturation in the gonad. Interestingly, in the past few years, additional pathways have become apparent in the search for a fish photoneuroendocrine system including the clock-gene network and kisspeptin signalling and although research on these topics are still in their infancy, it is moving at great pace. This review thus aims to bring together the current knowledge on the photic control of reproduction mainly focusing on seasonal temperate fish species and shape the current working hypotheses supported by recent findings obtained in teleosts or based on knowledge gathered in mammalian and avian species. Four of the main potential regulatory systems (light perception, melatonin, clock genes and kisspeptin) in fish reproduction are reviewed.
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Affiliation(s)
- H Migaud
- Reproduction and Genetics Group, Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, UK.
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Yasuo S, Yoshimura T, Ebihara S, Korf HW. Photoperiodic control of TSH-beta expression in the mammalian pars tuberalis has different impacts on the induction and suppression of the hypothalamo-hypopysial gonadal axis. J Neuroendocrinol 2010; 22:43-50. [PMID: 19912473 DOI: 10.1111/j.1365-2826.2009.01936.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Seasonal reproduction depends on photoperiod-regulated activation or suppression of the gonadal axis. Recent studies in quail have identified long-day induced TSH-beta expression in the pars tuberalis (PT) as a rapid trigger of gonadal activation. Thyroid-stimulating hormone (TSH) induces type 2 deiodinase (Dio2) in the ependymal cell layer (EC) of the infundibular recess to stimulate the gonadal axis. A similar mechanism is proposed in sheep and mice, but the experimental data on the temporal patterns of induction and suppression of TSH-beta and Dio2 expression are incomplete. In the present study, we examined the expression of TSH-beta and Dio2 in hamsters transferred from short- to long-day conditions for 9 days, and demonstrate the induction of TSH-beta and Dio2 on day 8 after transition. These data demonstrate the close relationship between TSH-beta and Dio2 expression in the inductive pathway. The temporal expression of TSH-beta and Dio2 in the suppressive pathway was also examined by s.c. melatonin injection, which mimics the transition from long to short days. Importantly, Dio2 expression in the EC is suppressed on day 1 after the onset of injection, whereas TSH-beta expression in the PT was not suppressed until day 10. These data suggest that regulated transcription of TSH-beta is involved in the induction of the gonadal axis in mammals, whereas the suppression of this axis is mediated by different mechanisms.
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Affiliation(s)
- S Yasuo
- Dr Senckenbergische Anatomie, Institute of Anatomie II, Goethe-University Frankfurt, Frankfurt am Main, Germany
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Cell organization of the rat pars tuberalis. Evidence for open communication between pars tuberalis cells, cerebrospinal fluid and tanycytes. Cell Tissue Res 2009; 339:359-81. [DOI: 10.1007/s00441-009-0885-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Accepted: 09/09/2009] [Indexed: 10/20/2022]
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Yasuo S, Yoshimura T. Comparative analysis of the molecular basis of photoperiodic signal transduction in vertebrates. Integr Comp Biol 2009; 49:507-18. [DOI: 10.1093/icb/icp011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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