1
|
Klosen P. Thirty-seven years of MT1 and MT2 melatonin receptor localization in the brain: Past and future challenges. J Pineal Res 2024; 76:e12955. [PMID: 38606787 DOI: 10.1111/jpi.12955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 02/21/2024] [Accepted: 03/31/2024] [Indexed: 04/13/2024]
Abstract
Identifying the target cells of a hormone is a key step in understanding its function. Once the molecular nature of the receptors for a hormone has been established, researchers can use several techniques to detect these receptors. Here I will review the different tools used over the years to localize melatonin receptors and the problems associated with each of these techniques. The radioligand 2-[125I] iodomelatonin was the first tool to allow localization of melatonin receptors on tissue sections. Once the MT1 and MT2 receptors were cloned, in situ hybridization could be used to detect the messenger RNA for these receptors. The deduced amino acid sequences for MT1 and MT2 receptors allowed the production of peptide immunogens to generate antibodies against the MT1 and MT2 receptors. Finally, transgenic reporters driven by the promoter elements of the MT1 and MT2 genes have been used to map the expression of MT1 and MT2 in the brain and the retina. Several issues have complicated the localization of melatonin receptors and the characterization of melatonin target cells over the last three decades. Melatonin receptors are expressed at low levels, leading to sensitivity issues for their detection. The second problem are specificity issues with antibodies directed against the MT1 and MT2 melatonin receptors. These receptors are G protein-coupled receptors and many antibodies directed against such receptors have been shown to present similar problems concerning their specificity. Despite these specificity problems which start to be seriously addressed by recent studies, antibodies will be important tools in the future to identify and phenotype melatonin target cells. However, we will have to be more stringent than previously when establishing their specificity. The results obtained by these antibodies will have to be confronted and be coherent with results obtained by other techniques.
Collapse
Affiliation(s)
- Paul Klosen
- Regulation and Disruption of Neuroendocrine Rhythms, Institute of Cellular and Integrative Neurosciences, INCI CNRS UPR-3212, University of Strasbourg, Strasbourg, France
| |
Collapse
|
2
|
Perea MF, Fernández EA, Garzón JP, Rosales CA, Hernández-Fonseca H, Perdomo DA, Perea FP. The moon cycle influences reproductive and productive traits in guinea pigs ( Cavia porcellus) from a tropical Andean area. Chronobiol Int 2024; 41:127-136. [PMID: 38093623 DOI: 10.1080/07420528.2023.2294044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 12/07/2023] [Indexed: 01/16/2024]
Abstract
There is currently innumerable evidence showing that the lunar cycle affects various reproductive aspects in farm animals. However, there is very little information on the effect of the lunar cycle on productive traits in these species. A retrospective study was conducted (2015-2018) to evaluate the influence of the lunar cycle on some reproductive and productive traits in a guinea pig (Cavia porcellus) production system in the southern Andean region of Ecuador. A total of 7352 productive and reproductive records of guinea pig females housed in 3 m2 cages with a breeding male were analyzed. The following variables were considered: offspring sex ratio, litter size per cage, number of weaned guinea pigs, mortality, individual and litter weaning weight of guinea pigs, and calving frequency. The lunar cycle was split into eight periods of ~3.7-d length each. Data were analyzed by logistic regression and general linear model, and means were compared by the least mean squares method of the SAS. The offspring sex ratio was not correlated to the lunar cycle. The lunar cycle at mating and calving influenced the litter size per cage, number of weaned, and mortality of guinea pigs. The individual and litter-weaning weights were influenced by the lunar cycle at calving. The frequency of calving was greater around the new and full moon than in the remaining periods of the lunar cycle. In conclusion, the lunar cycle influenced several productive and reproductive traits in guinea pigs, such as litter size, mortality, number of pups weaned, and individual and litter weaning weights. This valuable information may have practical applications in management of guinea pig production systems.
Collapse
Affiliation(s)
- Miguel F Perea
- Facultad de Ciencia y Tecnología, Escuela de Biología, Ecología y Gestión, Universidad del Azuay, Cuenca, Ecuador
| | - Estefanía A Fernández
- Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan P Garzón
- Estación Experimental del Austro, Instituto Nacional de Investigaciones Agropecuarias (INIAP), Azuay, Ecuador
| | - Cornelio A Rosales
- Facultad de Ciencias Agropecuarias, Universidad de Cuenca, Cuenca, Ecuador
| | - Hugo Hernández-Fonseca
- Department of Anatomy, Physiology and Pharmacology, School of Veterinary Medicine, St. George's University, St. George's, West Indies
| | - Daniel A Perdomo
- Departamento de Ciencias Agrarias, Universidad de Los Andes, Trujillo, Venezuela
| | - Fernando P Perea
- Facultad de Ciencias Agropecuarias, Universidad de Cuenca, Cuenca, Ecuador
- Departamento de Ciencias Agrarias, Universidad de Los Andes, Trujillo, Venezuela
| |
Collapse
|
3
|
Dardente H, Simonneaux V. GnRH and the photoperiodic control of seasonal reproduction: Delegating the task to kisspeptin and RFRP-3. J Neuroendocrinol 2022; 34:e13124. [PMID: 35384117 DOI: 10.1111/jne.13124] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/22/2022] [Accepted: 03/03/2022] [Indexed: 10/18/2022]
Abstract
Synchronization of mammalian breeding activity to the annual change of photoperiod and environmental conditions is of the utmost importance for individual survival and species perpetuation. Subsequent to the early 1960s, when the central role of melatonin in this adaptive process was demonstrated, our comprehension of the mechanisms through which light regulates gonadal activity has increased considerably. The current model for the photoperiodic neuroendocrine system points to pivotal roles for the melatonin-sensitive pars tuberalis (PT) and its seasonally-regulated production of thyroid-stimulating hormone (TSH), as well as for TSH-sensitive hypothalamic tanycytes, radial glia-like cells located in the basal part of the third ventricle. Tanycytes respond to TSH through increased expression of thyroid hormone (TH) deiodinase 2 (Dio2), which leads to heightened production of intrahypothalamic triiodothyronine (T3) during longer days of spring and summer. There is strong evidence that this local, long-day driven, increase in T3 links melatonin input at the PT to gonadotropin-releasing hormone (GnRH) output, to align breeding with the seasons. The mechanism(s) through which T3 impinges upon GnRH remain(s) unclear. However, two distinct neuronal populations of the medio-basal hypothalamus, which express the (Arg)(Phe)-amide peptides kisspeptin and RFamide-related peptide-3, appear to be well-positioned to relay this seasonal T3 message towards GnRH neurons. Here, we summarize our current understanding of the cellular, molecular and neuroendocrine players, which keep track of photoperiod and ultimately govern GnRH output and seasonal breeding.
Collapse
Affiliation(s)
- Hugues Dardente
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
| | - Valérie Simonneaux
- Institute for Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| |
Collapse
|
4
|
Seasonal Expression of Gonadotropin Genes in the Pituitary and Testes of Male Plateau Zokor (Eospalax baileyi). Animals (Basel) 2022; 12:ani12060725. [PMID: 35327122 PMCID: PMC8944513 DOI: 10.3390/ani12060725] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 03/11/2022] [Accepted: 03/11/2022] [Indexed: 01/30/2023] Open
Abstract
The gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), are glycoprotein hormones in the hypothalamic-pituitary-gonadal (HPG) axis and regulate mammalian reproduction. The expression of these genes in the plateau zokor (Eospalax baileyi) is poorly understood. We characterized the immunolocalization of the luteinizing hormone receptor (LHR) and follicle stimulating hormone receptor (FSHR) in the testes and evaluated the positive immunohistochemical results and the relative mRNA expression of gonadotropin genes. During the non-breeding season (September), the relative testes weight and the seminiferous tubule diameter were significantly reduced. All germ cell types were observed during the breeding season (May), whereas only spermatogonia were observed during the non-breeding season. LHR was present in the Leydig cells whereas FSHR was present in the Sertoli cells. The mean optical density was higher during the breeding season. The mRNA expression of LHβ and FSHβ was lower in the pituitary but LHR and FSHR genes expression were higher in the testes during the breeding season. These data elucidate the expression of gonadotropin genes in the HPG axis of the male plateau zokor and suggest that gonadotropins play a vital role in the regulation of seasonal breeding.
Collapse
|
5
|
Klosen P. Nonradioactive In Situ Hybridization of MT1 Melatonin Receptor for the Identification of Melatonin Target Cells. Methods Mol Biol 2022; 2550:219-241. [PMID: 36180696 DOI: 10.1007/978-1-0716-2593-4_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Identifying and phenotyping the target cells of a neuroendocrine messenger is one of the key steps to understand neuroendocrine networks and the physiological action of such messengers. In the absence of reliable antibodies directed against the receptor of a neuroendocrine messenger, detecting the expression of the messenger RNA of this receptor is an important tool to identify the target cells of a neuroendocrine messenger such as melatonin. While radioactive in situ hybridization has a higher sensitivity, nonradioactive in situ hybridization has a much better cellular resolution than radioactive in situ hybridization and is therefore better suited for phenotyping the target cells of melatonin. Here we describe a nonradioactive in situ hybridization protocol with its adaptations to various types of histological preparations. This protocol allowed the phenotyping of melatonin target cells in the pars tuberalis of the adenohypophysis, leading to the discovery of photoperiodic melatonin signaling from the pars tuberalis to the hypothalamus.
Collapse
Affiliation(s)
- Paul Klosen
- Institute of Cellular and Integrative Neurosciences, INCI CNRS UPR3212, University of Strasbourg, Strasbourg, France.
| |
Collapse
|
6
|
Dardente H, Migaud M. Thyroid hormone and hypothalamic stem cells in seasonal functions. VITAMINS AND HORMONES 2021; 116:91-131. [PMID: 33752829 DOI: 10.1016/bs.vh.2021.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Seasonal rhythms are a pervasive feature of most living organisms, which underlie yearly timeliness in breeding, migration, hibernation or weight gain and loss. To achieve this, organisms have developed inner timing devices (circannual clocks) that endow them with the ability to predict then anticipate changes to come, usually using daylength as the proximate cue. In Vertebrates, daylength interpretation involves photoperiodic control of TSH production by the pars tuberalis (PT) of the pituitary, which governs a seasonal switch in thyroid hormone (TH) availability in the neighboring hypothalamus. Tanycytes, specialized glial cells lining the third ventricle (3V), are responsible for this TH output through the opposite, PT-TSH-driven, seasonal control of deiodinases 2/3 (Dio 2/3). Tanycytes comprise a photoperiod-sensitive stem cell niche and TH is known to play major roles in cell proliferation and differentiation, which suggests that seasonal control of tanycyte proliferation may be involved in the photoperiodic synchronization of seasonal rhythms. Here we review our current knowledge of the molecular and neuroendocrine pathway linking photoperiodic information to seasonal changes in physiological functions and discuss the potential implication of tanycytes, TH and cell proliferation in seasonal timing.
Collapse
Affiliation(s)
- Hugues Dardente
- PRC, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France.
| | - Martine Migaud
- PRC, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| |
Collapse
|
7
|
Ertek S. Molecular economy of nature with two thyrotropins from different parts of the pituitary: pars tuberalis thyroid-stimulating hormone and pars distalis thyroid-stimulating hormone. Arch Med Sci 2021; 17:189-195. [PMID: 33488871 PMCID: PMC7811323 DOI: 10.5114/aoms/102476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 01/01/2019] [Indexed: 11/19/2022] Open
Abstract
Thyrotropin (TSH) is classically known to be regulated by negative feedback from thyroid hormones and stimulated by thyrotropin-releasing hormone (TRH) from the hypothalamus. At the end of the 1990s, studies showed that thyrotroph cells from the pars tuberalis (PT) did not have TRH receptors and their TSH regulation was independent from TRH stimulation. Instead, PT-thyrotroph cells were shown to have melatonin-1 (MT-1) receptors and melatonin secretion from the pineal gland stimulates TSH-β subunit formation in PT. Electron microscopy examinations also revealed some important differences between PT and pars distalis (PD) thyrotrophs. PT-TSH also have low bioactivity in the peripheral circulation. Studies showed that they have different glycosylations and PT-TSH forms macro-TSH complexes in the periphery and has a longer half-life. Photoperiodism affects LH levels in animals via decreased melatonin causing increased TSH-β subunit expression and induction of deiodinase-2 (DIO-2) in the brain. Mammals need a light stimulus carried into the suprachiasmatic nucleus (which is a circadian clock) and then transferred to the pineal gland to synthesize melatonin, but birds have deep brain receptors and they are stimulated directly by light stimuli to have increased PT-TSH, without the need for melatonin. Photoperiodic regulations via TSH and DIO 2/3 also have a role in appetite, seasonal immune regulation, food intake and nest-making behaviour in animals. Since humans have no clear seasonal breeding period, such studies as recent ''domestication locus'' studies in poultry are interesting. PT-TSH that works like a neurotransmitter in the brain may become an important target for future studies about humans.
Collapse
Affiliation(s)
- Sibel Ertek
- Department of Endocrinology and Metabolic Diseases, Memorial Ankara Hospital, Ankara, Turkey
| |
Collapse
|
8
|
Wood SH, Hindle MM, Mizoro Y, Cheng Y, Saer BRC, Miedzinska K, Christian HC, Begley N, McNeilly J, McNeilly AS, Meddle SL, Burt DW, Loudon ASI. Circadian clock mechanism driving mammalian photoperiodism. Nat Commun 2020; 11:4291. [PMID: 32855407 PMCID: PMC7453030 DOI: 10.1038/s41467-020-18061-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 07/27/2020] [Indexed: 12/19/2022] Open
Abstract
The annual photoperiod cycle provides the critical environmental cue synchronizing rhythms of life in seasonal habitats. In 1936, Bünning proposed a circadian-based coincidence timer for photoperiodic synchronization in plants. Formal studies support the universality of this so-called coincidence timer, but we lack understanding of the mechanisms involved. Here we show in mammals that long photoperiods induce the circadian transcription factor BMAL2, in the pars tuberalis of the pituitary, and triggers summer biology through the eyes absent/thyrotrophin (EYA3/TSH) pathway. Conversely, long-duration melatonin signals on short photoperiods induce circadian repressors including DEC1, suppressing BMAL2 and the EYA3/TSH pathway, triggering winter biology. These actions are associated with progressive genome-wide changes in chromatin state, elaborating the effect of the circadian coincidence timer. Hence, circadian clock-pituitary epigenetic pathway interactions form the basis of the mammalian coincidence timer mechanism. Our results constitute a blueprint for circadian-based seasonal timekeeping in vertebrates.
Collapse
Affiliation(s)
- S H Wood
- Centre for Biological Timing, Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK
- Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, Tromsø, 9037, Norway
| | - M M Hindle
- The Roslin Institute, and Royal (Dick) School of Veterinary Studies University of Edinburgh, Roslin, Midlothian, EH25 9PRG, UK
| | - Y Mizoro
- Centre for Biological Timing, Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - Y Cheng
- UQ Genomics Initiative, The University of Queensland, Brisbane, QLD, 4072, Australia
- School of Life and Environmental Sciences, Faculty of Science, The University of Sydney, Camperdown, NSW, Australia
| | - B R C Saer
- Centre for Biological Timing, Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - K Miedzinska
- The Roslin Institute, and Royal (Dick) School of Veterinary Studies University of Edinburgh, Roslin, Midlothian, EH25 9PRG, UK
| | - H C Christian
- University of Oxford, Department of Physiology, Anatomy and Genetics, Le Gros Clark Building, South Parks Road, Oxford, OX1 3QX, UK
| | - N Begley
- Centre for Biological Timing, Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - J McNeilly
- MRC Centre for Reproductive Health, Queen's Medical Research Institute, Edinburgh, EH16 4TJ, UK
| | - A S McNeilly
- MRC Centre for Reproductive Health, Queen's Medical Research Institute, Edinburgh, EH16 4TJ, UK
| | - S L Meddle
- The Roslin Institute, and Royal (Dick) School of Veterinary Studies University of Edinburgh, Roslin, Midlothian, EH25 9PRG, UK
| | - D W Burt
- The Roslin Institute, and Royal (Dick) School of Veterinary Studies University of Edinburgh, Roslin, Midlothian, EH25 9PRG, UK
- UQ Genomics Initiative, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - A S I Loudon
- Centre for Biological Timing, Faculty of Life Sciences, University of Manchester, Manchester, M13 9PT, UK.
| |
Collapse
|
9
|
Lomet D, Druart X, Hazlerigg D, Beltramo M, Dardente H. Circuit-level analysis identifies target genes of sex steroids in ewe seasonal breeding. Mol Cell Endocrinol 2020; 512:110825. [PMID: 32422398 DOI: 10.1016/j.mce.2020.110825] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/26/2020] [Accepted: 04/19/2020] [Indexed: 02/04/2023]
Abstract
Thyroid hormone (TH) and estradiol (E2) direct seasonal switches in ovine reproductive physiology. In sheep, as in other mammals and birds, control of thyrotropin (TSH) production by the pars tuberalis (PT) links photoperiod responsiveness to seasonal breeding. PT-derived TSH governs opposite seasonal patterns of the TH deiodinases Dio2/Dio3 expression in tanycytes of the neighboring medio-basal hypothalamus (MBH), which explain the key role of TH. We recently used RNA-Seq to identify seasonal markers in the MBH and define the impact of TH. This impact was found to be quite limited, in terms of number of target genes, and very restricted with regards to neuroanatomical location, as TH specifically impacts genes expressed in tanycytes and hypothalamus, not in the PT. Here we address the impact of E2 on these seasonal markers, which are specifically expressed in either PT, tanycytes or hypothalamus. We also investigate if progesterone (P4) may be involved in timing the seasonal transition to anestrus. Our analysis provides circuit-level insights into the impact of sex steroids on the ewe seasonal breeding cycle. First, seasonal gene expression in the PT is independent of the sex steroid status. The fact that seasonal gene expression in the PT is also TH-independent strengthens the view that the PT is a circannual timer. Second, select tanycytic markers display some level of responsiveness to E2 and P4, which indicates another potential level of feedback control by sex steroids. Third, Kiss1 neurons of the arcuate nucleus are responsive to both TH and E2, which places them at the crossroads of photoperiodic transduction pathway and sex steroid feedback. This provides strong support to the concept that these Kiss1 neurons are pivotal to the long-recognized "seasonal switch in the ability of E2 to exert negative feedback", which drives seasonal breeding.
Collapse
Affiliation(s)
- Didier Lomet
- Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - Xavier Druart
- Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - David Hazlerigg
- Department of Arctic and Marine Biology, University of Tromsø, 9037, Tromsø, Norway
| | - Massimiliano Beltramo
- Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - Hugues Dardente
- Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France.
| |
Collapse
|
10
|
Ciani E, Haug TM, Maugars G, Weltzien FA, Falcón J, Fontaine R. Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts. Front Endocrinol (Lausanne) 2020; 11:605111. [PMID: 33505357 PMCID: PMC7831660 DOI: 10.3389/fendo.2020.605111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/12/2020] [Indexed: 01/01/2023] Open
Abstract
Melatonin is a key hormone involved in the photoperiodic signaling pathway. In both teleosts and mammals, melatonin produced in the pineal gland at night is released into the blood and cerebrospinal fluid, providing rhythmic information to the whole organism. Melatonin acts via specific receptors, allowing the synchronization of daily and annual physiological rhythms to environmental conditions. The pituitary gland, which produces several hormones involved in a variety of physiological processes such as growth, metabolism, stress and reproduction, is an important target of melatonin. Melatonin modulates pituitary cellular activities, adjusting the synthesis and release of the different pituitary hormones to the functional demands, which changes during the day, seasons and life stages. It is, however, not always clear whether melatonin acts directly or indirectly on the pituitary. Indeed, melatonin also acts both upstream, on brain centers that control the pituitary hormone production and release, as well as downstream, on the tissues targeted by the pituitary hormones, which provide positive and negative feedback to the pituitary gland. In this review, we describe the known pathways through which melatonin modulates anterior pituitary hormonal production, distinguishing indirect effects mediated by brain centers from direct effects on the anterior pituitary. We also highlight similarities and differences between teleosts and mammals, drawing attention to knowledge gaps, and suggesting aims for future research.
Collapse
Affiliation(s)
- Elia Ciani
- Department of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Trude M. Haug
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Gersende Maugars
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Finn-Arne Weltzien
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
| | - Jack Falcón
- Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), MNHN, CNRS FRE 2030, SU, IRD 207, UCN, UA, Paris, France
| | - Romain Fontaine
- Physiology Unit, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Oslo, Norway
- *Correspondence: Romain Fontaine,
| |
Collapse
|
11
|
Klosen P, Lapmanee S, Schuster C, Guardiola B, Hicks D, Pevet P, Felder-Schmittbuhl MP. MT1 and MT2 melatonin receptors are expressed in nonoverlapping neuronal populations. J Pineal Res 2019; 67:e12575. [PMID: 30937953 DOI: 10.1111/jpi.12575] [Citation(s) in RCA: 40] [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: 02/08/2019] [Revised: 03/07/2019] [Accepted: 03/25/2019] [Indexed: 12/15/2022]
Abstract
Melatonin (MLT) exerts its physiological effects principally through two high-affinity membrane receptors MT1 and MT2. Understanding the exact mechanism of MLT action necessitates the use of highly selective agonists/antagonists to stimulate/inhibit a given MLT receptor. The respective distribution of MT1 and MT2 within the CNS and elsewhere is controversial, and here we used a "knock-in" strategy replacing MT1 or MT2 coding sequences with a LacZ reporter. The data show striking differences in the distribution of MT1 and MT2 receptors in the mouse brain: whereas the MT1 subtype was expressed in very few structures (notably including the suprachiasmatic nucleus and pars tuberalis), MT2 subtype receptors were identified within numerous brain regions including the olfactory bulb, forebrain, hippocampus, amygdala and superior colliculus. Co-expression of the two subtypes was observed in very few structures, and even within these areas they were rarely present in the same individual cell. In conclusion, the expression and distribution of MT2 receptors are much more widespread than previously thought, and there is virtually no correspondence between MT1 and MT2 cellular expression. The precise phenotyping of cells/neurons containing MT1 or MT2 receptor subtypes opens new perspectives for the characterization of links between MLT brain targets, MLT actions and specific MLT receptor subtypes.
Collapse
Affiliation(s)
- Paul Klosen
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | - Sarawut Lapmanee
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | | | | | - David Hicks
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | - Paul Pevet
- Institute for Cellular and Integrative Neurosciences (UPR 3212), CNRS and University of Strasbourg, Strasbourg, France
| | | |
Collapse
|
12
|
Abstract
For many years now a treatment mitigating the debilitating effects of jet lag has been sought. Rapid travel across time zones leads, in most people, to temporary symptoms, in particular poor sleep, daytime alertness and poor performance. Mis-timed circadian rhythms are considered to be the main factor underlying jet-lag symptoms, together with the sleep deprivation from long haul flights. Virtually all aspects of physiology are rhythmic, from cells to systems, and circadian rhythms are coordinated by a central pacemaker or clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN adapts slowly to changes in time zone, and peripheral clocks or oscillators adapt at different rates, such that the organism is in a state of desynchrony from the external environment and internally. Light exposure is the main factor controlling the circadian system and needs to be considered together with any pharmacological interventions. This review covers the relatively new chronobiotic drugs, which can hasten adaptation of the circadian system, together with drugs directly affecting alertness and sleep propensity. No current treatment can instantly shift circadian phase to a new time zone; however, adaptation can be hastened. The melatoninergic drugs are promising but larger trials in real-life situations are needed. For short stopovers it is recommended to preserve sleep and alertness without necessarily modifying the circadian system. New research suggests that modification of clock function via genetic manipulation may one day have clinical applications.
Collapse
Affiliation(s)
- Josephine Arendt
- Faculty of Health and Medical Sciences (FHMS), University of Surrey, Guildford, Surrey, GU2 7XH, UK.
| |
Collapse
|
13
|
Rodríguez-Rodríguez A, Lazcano I, Sánchez-Jaramillo E, Uribe RM, Jaimes-Hoy L, Joseph-Bravo P, Charli JL. Tanycytes and the Control of Thyrotropin-Releasing Hormone Flux Into Portal Capillaries. Front Endocrinol (Lausanne) 2019; 10:401. [PMID: 31293518 PMCID: PMC6603095 DOI: 10.3389/fendo.2019.00401] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 06/06/2019] [Indexed: 12/17/2022] Open
Abstract
Central and peripheral mechanisms that modulate energy intake, partition and expenditure determine energy homeostasis. Thyroid hormones (TH) regulate energy expenditure through the control of basal metabolic rate and thermogenesis; they also modulate food intake. TH concentrations are regulated by the hypothalamus-pituitary-thyroid (HPT) axis, and by transport and metabolism in blood and target tissues. In mammals, hypophysiotropic thyrotropin-releasing hormone (TRH) neurons of the paraventricular nucleus of the hypothalamus integrate energy-related information. They project to the external zone of the median eminence (ME), a brain circumventricular organ rich in neuron terminal varicosities and buttons, tanycytes, other glial cells and capillaries. These capillary vessels form a portal system that links the base of the hypothalamus with the anterior pituitary. Tanycytes of the medio-basal hypothalamus express a repertoire of proteins involved in transport, sensing, and metabolism of TH; among them is type 2 deiodinase, a source of 3,3',5-triiodo-L-thyronine necessary for negative feedback on TRH neurons. Tanycytes subtypes are distinguished by position and phenotype. The end-feet of β2-tanycytes intermingle with TRH varicosities and terminals in the external layer of the ME and terminate close to the ME capillaries. Besides type 2 deiodinase, β2-tanycytes express the TRH-degrading ectoenzyme (TRH-DE); this enzyme likely controls the amount of TRH entering portal vessels. TRH-DE is rapidly upregulated by TH, contributing to TH negative feedback on HPT axis. Alterations in energy balance also regulate the expression and activity of TRH-DE in the ME, making β2-tanycytes a hub for energy-related regulation of HPT axis activity. β2-tanycytes also express TRH-R1, which mediates positive effects of TRH on TRH-DE activity and the size of β2-tanycyte end-feet contacts with the basal lamina adjacent to ME capillaries. These end-feet associations with ME capillaries, and TRH-DE activity, appear to coordinately control HPT axis activity. Thus, down-stream of neuronal control of TRH release by action potentials arrival in the external layer of the median eminence, imbricated intercellular processes may coordinate the flux of TRH into the portal capillaries. In conclusion, β2-tanycytes appear as a critical cellular element for the somatic and post-secretory control of TRH flux into portal vessels, and HPT axis regulation in mammals.
Collapse
Affiliation(s)
- Adair Rodríguez-Rodríguez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Iván Lazcano
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Edith Sánchez-Jaramillo
- Laboratorio de Neuroendocrinología Molecular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Rosa María Uribe
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Lorraine Jaimes-Hoy
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Patricia Joseph-Bravo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| |
Collapse
|
14
|
Melatonin MT1 receptor as a novel target in neuropsychopharmacology: MT1 ligands, pathophysiological and therapeutic implications, and perspectives. Pharmacol Res 2019; 144:343-356. [DOI: 10.1016/j.phrs.2019.04.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 03/06/2019] [Accepted: 04/11/2019] [Indexed: 12/15/2022]
|
15
|
Dardente H, Wood S, Ebling F, Sáenz de Miera C. An integrative view of mammalian seasonal neuroendocrinology. J Neuroendocrinol 2019; 31:e12729. [PMID: 31059174 DOI: 10.1111/jne.12729] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/29/2019] [Accepted: 04/30/2019] [Indexed: 12/29/2022]
Abstract
Seasonal neuroendocrine cycles that govern annual changes in reproductive activity, energy metabolism and hair growth are almost ubiquitous in mammals that have evolved at temperate and polar latitudes. Changes in nocturnal melatonin secretion regulating gene expression in the pars tuberalis (PT) of the pituitary stalk are a critical common feature in seasonal mammals. The PT sends signal(s) to the pars distalis of the pituitary to regulate prolactin secretion and thus the annual moult cycle. The PT also signals in a retrograde manner via thyroid-stimulating hormone to tanycytes, which line the ventral wall of the third ventricle in the hypothalamus. Tanycytes show seasonal plasticity in gene expression and play a pivotal role in regulating local thyroid hormone (TH) availability. Within the mediobasal hypothalamus, the cellular and molecular targets of TH remain elusive. However, two populations of hypothalamic neurones, which produce the RF-amide neuropeptides kisspeptin and RFRP3 (RF-amide related peptide 3), are plausible relays between TH and the gonadotrophin-releasing hormone-pituitary-gonadal axis. By contrast, the ways by which TH also impinges on hypothalamic systems regulating energy intake and expenditure remain unknown. Here, we review the neuroendocrine underpinnings of seasonality and identify several areas that warrant further research.
Collapse
Affiliation(s)
- Hugues Dardente
- Physiologie de la Reproduction et des Comportements, INRA, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Shona Wood
- Department of Arctic and Marine Biology, The Arctic University of Norway, Tromsø, Norway
| | - Francis Ebling
- School of Life Sciences, University of Nottingham, Nottingham, UK
| | | |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Tsutsui K, Ubuka T. Editorial: Progress in Reproductive Neuroendocrinology in Vertebrates. Front Endocrinol (Lausanne) 2019; 10:895. [PMID: 31920995 PMCID: PMC6930872 DOI: 10.3389/fendo.2019.00895] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 12/06/2019] [Indexed: 11/13/2022] Open
|
18
|
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: 25] [Impact Index Per Article: 5.0] [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.
Collapse
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
| |
Collapse
|
19
|
Angelopoulou E, Quignon C, Kriegsfeld LJ, Simonneaux V. Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction. Front Endocrinol (Lausanne) 2019; 10:183. [PMID: 31024442 PMCID: PMC6467943 DOI: 10.3389/fendo.2019.00183] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/05/2019] [Indexed: 12/20/2022] Open
Abstract
Adaptation of reproductive activity to environmental changes is essential for breeding success and offspring survival. In mammals, the reproductive system displays regular cycles of activation and inactivation which are synchronized with seasonal and/or daily rhythms in environmental factors, notably light intensity and duration. Thus, most species adapt their breeding activity along the year to ensure that birth and weaning of the offspring occur at a time when resources are optimal. Additionally, female reproductive activity is highest at the beginning of the active phase during the period of full oocyte maturation, in order to improve breeding success. In reproductive physiology, it is therefore fundamental to delineate how geophysical signals are integrated in the hypothalamo-pituitary-gonadal axis, notably by the neurons expressing gonadotropin releasing hormone (GnRH). Several neurochemicals have been reported to regulate GnRH neuronal activity, but recently two hypothalamic neuropeptides belonging to the superfamily of (Arg)(Phe)-amide peptides, RFRP-3 and kisspeptin, have emerged as critical for the integration of environmental cues within the reproductive axis. The goal of this review is to survey the current understanding of the role played by RFRP-3 in the temporal regulation of reproduction, and consider how its effect might combine with that of kisspeptin to improve the synchronization of reproduction to environmental challenges.
Collapse
Affiliation(s)
- Eleni Angelopoulou
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
- Netherlands Institute for Neuroscience (NIN), Amsterdam, Netherlands
| | - Clarisse Quignon
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Lance J. Kriegsfeld
- Department of Psychology, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
- *Correspondence: Valérie Simonneaux
| |
Collapse
|
20
|
Sáenz de Miera C. Maternal photoperiodic programming enlightens the internal regulation of thyroid-hormone deiodinases in tanycytes. J Neuroendocrinol 2019; 31:e12679. [PMID: 30585670 DOI: 10.1111/jne.12679] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 12/09/2018] [Accepted: 12/20/2018] [Indexed: 12/15/2022]
Abstract
Seasonal rhythms in physiology are widespread among mammals living in temperate zones. These rhythms rely on the external photoperiodic signal being entrained to the seasons, although they persist under constant conditions, revealing their endogenous origin. Internal long-term timing (circannual cycles) can be revealed in the laboratory as photoperiodic history-dependent responses, comprising the ability to respond differently to similar photoperiodic cues based on prior photoperiodic experience. In juveniles, history-dependence relies on the photoperiod transmitted by the mother to the fetus in utero, a phenomenon known as "maternal photoperiodic programming" (MPP). The response to photoperiod in mammals involves the nocturnal pineal hormone melatonin, which regulates a neuroendocrine network including thyrotrophin in the pars tuberalis and deiodinases in tanycytes, resulting in changes in thyroid hormone in the mediobasal hypothalamus. This review addresses MPP and discusses the latest findings on its impact on the thyrotrophin/deiodinase network. Finally, commonalities between MPP and other instances of endogenous seasonal timing are considered, and a unifying scheme is suggested in which timing arises from a long-term communication between the pars tuberalis and the hypothalamus and resultant spontaneous changes in local thyroid hormone status, independently of the pineal melatonin signal.
Collapse
Affiliation(s)
- Cristina Sáenz de Miera
- Department Neurobiology of Rhythms, Institute for Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| |
Collapse
|
21
|
Simonneaux V. A Kiss to drive rhythms in reproduction. Eur J Neurosci 2018; 51:509-530. [DOI: 10.1111/ejn.14287] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/08/2018] [Accepted: 11/19/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Valérie Simonneaux
- Institut des Neurosciences Cellulaires et IntégrativesCNRSUniversité de Strasbourg Strasbourg France
| |
Collapse
|
22
|
Cipolla-Neto J, Amaral FGD. Melatonin as a Hormone: New Physiological and Clinical Insights. Endocr Rev 2018; 39:990-1028. [PMID: 30215696 DOI: 10.1210/er.2018-00084] [Citation(s) in RCA: 327] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 06/21/2018] [Indexed: 02/07/2023]
Abstract
Melatonin is a ubiquitous molecule present in almost every live being from bacteria to humans. In vertebrates, besides being produced in peripheral tissues and acting as an autocrine and paracrine signal, melatonin is centrally synthetized by a neuroendocrine organ, the pineal gland. Independently of the considered species, pineal hormone melatonin is always produced during the night and its production and secretory episode duration are directly dependent on the length of the night. As its production is tightly linked to the light/dark cycle, melatonin main hormonal systemic integrative action is to coordinate behavioral and physiological adaptations to the environmental geophysical day and season. The circadian signal is dependent on its daily production regularity, on the contrast between day and night concentrations, and on specially developed ways of action. During its daily secretory episode, melatonin coordinates the night adaptive physiology through immediate effects and primes the day adaptive responses through prospective effects that will only appear at daytime, when melatonin is absent. Similarly, the annual history of the daily melatonin secretory episode duration primes the central nervous/endocrine system to the seasons to come. Remarkably, maternal melatonin programs the fetuses' behavior and physiology to cope with the environmental light/dark cycle and season after birth. These unique ways of action turn melatonin into a biological time-domain-acting molecule. The present review focuses on the above considerations, proposes a putative classification of clinical melatonin dysfunctions, and discusses general guidelines to the therapeutic use of melatonin.
Collapse
Affiliation(s)
- José Cipolla-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | | |
Collapse
|
23
|
Abstract
Life in seasonally changing environments is challenging. Biological systems have to not only respond directly to the environment, but also schedule life history events in anticipation of seasonal changes. The cellular and molecular basis of how these events are scheduled is unknown. Cellular decision-making processes in response to signals above certain thresholds regularly occur i.e. cellular fate determination, apoptosis and firing of action potentials. Binary switches, the result of cellular decision-making processes, are defined as a change in phenotype between two stable states. A recent study presents evidence of a binary switch operating in the pars tuberalis (PT) of the pituitary, seemingly timing seasonal reproduction in sheep. Though, how a binary switch would allow for anticipation of seasonal environmental changes, not just direct responsiveness, is unclear. The purpose of this review is to assess the evidence for a binary switching mechanism timing seasonal reproduction and to hypothesize how a binary switch would allow biological processes to be timed over weeks to years. I draw parallels with mechanisms used in development, cell fate determination and seasonal timing in plants. I propose that the adult PT is a plastic tissue, showing a seasonal cycle of cellular differentiation, and that the underlying processes are likely to be epigenetic. Therefore, considering the mechanisms behind adult cellular plasticity offers a framework to hypothesize how a long-term timer functions within the PT.
Collapse
Affiliation(s)
- Shona H Wood
- Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø, Norway
- Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, Manchester, UK
| |
Collapse
|
24
|
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.
Collapse
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.
| |
Collapse
|
25
|
Lomet D, Cognié J, Chesneau D, Dubois E, Hazlerigg D, Dardente H. The impact of thyroid hormone in seasonal breeding has a restricted transcriptional signature. Cell Mol Life Sci 2018; 75:905-919. [PMID: 28975373 PMCID: PMC11105383 DOI: 10.1007/s00018-017-2667-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/05/2017] [Accepted: 09/26/2017] [Indexed: 01/16/2023]
Abstract
Thyroid hormone (TH) directs seasonal breeding through reciprocal regulation of TH deiodinase (Dio2/Dio3) gene expression in tanycytes in the ependymal zone of the medio-basal hypothalamus (MBH). Thyrotropin secretion by the pars tuberalis (PT) is a major photoperiod-dependent upstream regulator of Dio2/Dio3 gene expression. Long days enhance thyrotropin production, which increases Dio2 expression and suppresses Dio3 expression, thereby heightening TH signaling in the MBH. Short days appear to exert the converse effect. Here, we combined endocrine profiling and transcriptomics to understand how photoperiod and TH control the ovine reproductive status through effects on hypothalamic function. Almost 3000 genes showed altered hypothalamic expression between the breeding- and non-breeding seasons, showing gene ontology enrichment for cell signaling, epigenetics and neural plasticity. In contrast, acute switching from a short (SP) to a long photoperiod (LP) affected the expression of a much smaller core of 134 LP-responsive genes, including a canonical group previously linked to photoperiodic synchronization. Reproductive switch-off at the end of the winter breeding season was completely blocked by thyroidectomy (THX), despite a very modest effect on the hypothalamic transcriptome. Only 49 genes displayed altered expression between intact and THX ewes, including less than 10% of the LP-induced gene set. Neuroanatomical mapping showed that many LP-induced genes were expressed in the PT, independently of the TH status. In contrast, TH-sensitive seasonal genes were principally expressed in the ependymal zone. These data highlight the distinctions between seasonal remodeling effects, which appear to be largely independent of TH, and TH-dependent localised effects which are permissive for transition to the non-breeding state.
Collapse
Affiliation(s)
- Didier Lomet
- PRC, INRA, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - Juliette Cognié
- PRC, INRA, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - Didier Chesneau
- PRC, INRA, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France
| | - Emeric Dubois
- MGX-Montpellier GenomiX, Institut de Génomique Fonctionnelle, 34094, Montpellier, France
| | - David Hazlerigg
- Department of Arctic and Marine Biology, University of Tromsø, 9037, Tromsø, Norway
| | - Hugues Dardente
- PRC, INRA, CNRS, IFCE, Université de Tours, 37380, Nouzilly, France.
| |
Collapse
|
26
|
Wood S, Loudon A. The pars tuberalis: The site of the circannual clock in mammals? Gen Comp Endocrinol 2018; 258:222-235. [PMID: 28669798 DOI: 10.1016/j.ygcen.2017.06.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/23/2017] [Accepted: 06/29/2017] [Indexed: 12/12/2022]
Abstract
Accurate timing and physiological adaptation to anticipate seasonal changes are an essential requirement for an organism's survival. In contrast to all other environmental cues, photoperiod offers a highly predictive signal that can be reliably used to activate a seasonal adaptive programme at the correct time of year. Coupled to photoperiod sensing, it is apparent that many organisms have evolved innate long-term timekeeping systems, allowing reliable anticipation of forthcoming environmental changes. The fundamental biological processes giving rise to innate long-term timing, with which the photoperiod-sensing pathway engages, are not known for any organism. There is growing evidence that the pars tuberalis (PT) of the pituitary, which acts as a primary transducer of photoperiodic input, may be the site of the innate long-term timer or "circannual clock". Current research has led to the proposition that the PT-specific thyrotroph may act as a seasonal calendar cell, driving both hypothalamic and pituitary endocrine circuits. Based on this research we propose that the mechanistic basis for the circannual rhythm appears to be deeply conserved, driven by a binary switching cell based accumulator, analogous to that proposed for development. We review the apparent conservation of function and pathways to suggest that these broad principles may apply across the vertebrate lineage and even share characteristics with processes driving seasonal adaptation in plants.
Collapse
Affiliation(s)
- Shona Wood
- Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, A.V. Hill Building, Oxford Road, Manchester M13 9PT, UK.
| | - Andrew Loudon
- Faculty of Biology, Medicine and Health, School of Medical Sciences, University of Manchester, A.V. Hill Building, Oxford Road, Manchester M13 9PT, UK
| |
Collapse
|
27
|
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.
Collapse
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.
| |
Collapse
|
28
|
Melatonin receptors: distribution in mammalian brain and their respective putative functions. Brain Struct Funct 2017; 222:2921-2939. [DOI: 10.1007/s00429-017-1439-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 04/28/2017] [Indexed: 12/15/2022]
|
29
|
Mechanisms regulating angiogenesis underlie seasonal control of pituitary function. Proc Natl Acad Sci U S A 2017; 114:E2514-E2523. [PMID: 28270617 DOI: 10.1073/pnas.1618917114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Seasonal changes in mammalian physiology, such as those affecting reproduction, hibernation, and metabolism, are controlled by pituitary hormones released in response to annual environmental changes. In temperate zones, the primary environmental cue driving seasonal reproductive cycles is the change in day length (i.e., photoperiod), encoded by the pattern of melatonin secretion from the pineal gland. However, although reproduction relies on hypothalamic gonadotrophin-releasing hormone output, and most cells producing reproductive hormones are in the pars distalis (PD) of the pituitary, melatonin receptors are localized in the pars tuberalis (PT), a physically and functionally separate part of the gland. How melatonin in the PT controls the PD is not understood. Here we show that melatonin time-dependently acts on its receptors in the PT to alter splicing of vascular endothelial growth factor (VEGF). Outside the breeding season (BS), angiogenic VEGF-A stimulates vessel growth in the infundibulum, aiding vascular communication among the PT, PD, and brain. This also acts on VEGF receptor 2 (VEGFR2) expressed in PD prolactin-producing cells known to impair gonadotrophin secretion. In contrast, in the BS, melatonin releases antiangiogenic VEGF-Axxxb from the PT, inhibiting infundibular angiogenesis and diminishing lactotroph (LT) VEGFR2 expression, lifting reproductive axis repression in response to shorter day lengths. The time-dependent, melatonin-induced differential expression of VEGF-A isoforms culminates in alterations in gonadotroph function opposite to those of LTs, with up-regulation and down-regulation of gonadotrophin gene expression during the breeding and nonbreeding seasons, respectively. These results provide a mechanism by which melatonin can control pituitary function in a seasonal manner.
Collapse
|
30
|
Pévet P. Melatonin receptors as therapeutic targets in the suprachiasmatic nucleus. Expert Opin Ther Targets 2016; 20:1209-18. [DOI: 10.1080/14728222.2016.1179284] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Paul Pévet
- Institut des neurosciences cellulaires et Integratives, INCI UPR 3212, CNRS and the University of Strasbourg, Strasbourg, France
| |
Collapse
|
31
|
Quillet R, Ayachi S, Bihel F, Elhabazi K, Ilien B, Simonin F. RF-amide neuropeptides and their receptors in Mammals: Pharmacological properties, drug development and main physiological functions. Pharmacol Ther 2016; 160:84-132. [PMID: 26896564 DOI: 10.1016/j.pharmthera.2016.02.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
RF-amide neuropeptides, with their typical Arg-Phe-NH2 signature at their carboxyl C-termini, belong to a lineage of peptides that spans almost the entire life tree. Throughout evolution, RF-amide peptides and their receptors preserved fundamental roles in reproduction and feeding, both in Vertebrates and Invertebrates. The scope of this review is to summarize the current knowledge on the RF-amide systems in Mammals from historical aspects to therapeutic opportunities. Taking advantage of the most recent findings in the field, special focus will be given on molecular and pharmacological properties of RF-amide peptides and their receptors as well as on their implication in the control of different physiological functions including feeding, reproduction and pain. Recent progress on the development of drugs that target RF-amide receptors will also be addressed.
Collapse
Affiliation(s)
- Raphaëlle Quillet
- Biotechnologie et Signalisation Cellulaire, UMR 7242 CNRS, Université de Strasbourg, Illkirch, France
| | - Safia Ayachi
- Biotechnologie et Signalisation Cellulaire, UMR 7242 CNRS, Université de Strasbourg, Illkirch, France
| | - Frédéric Bihel
- Laboratoire Innovation Thérapeutique, UMR 7200 CNRS, Université de Strasbourg, Illkirch, France
| | - Khadija Elhabazi
- Biotechnologie et Signalisation Cellulaire, UMR 7242 CNRS, Université de Strasbourg, Illkirch, France
| | - Brigitte Ilien
- Biotechnologie et Signalisation Cellulaire, UMR 7242 CNRS, Université de Strasbourg, Illkirch, France
| | - Frédéric Simonin
- Biotechnologie et Signalisation Cellulaire, UMR 7242 CNRS, Université de Strasbourg, Illkirch, France.
| |
Collapse
|
32
|
Maeda R, Shimo T, Nakane Y, Nakao N, Yoshimura T. Ontogeny of the Saccus Vasculosus, a Seasonal Sensor in Fish. Endocrinology 2015; 156:4238-43. [PMID: 26270731 DOI: 10.1210/en.2015-1415] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
TSH secreted from the pars distalis (PD) of the pituitary gland stimulates the thyroid gland. In contrast, TSH secreted from the pars tuberalis (PT) of the pituitary gland regulates seasonal reproduction. The ontogeny of thyrotrophs and the regulatory mechanisms of TSH are apparently different between the PD and the PT. Interestingly, fish do not have an anatomically distinct PT, and the saccus vasculosus (SV) of fish is suggested to act as a seasonal sensor. Thus, it is possible that the SV is analogous to the PT. Here we examined the ontogeny of the pituitary gland and SV using rainbow trout. A histological analysis demonstrated the development of the pituitary anlage followed by that of the SV. Lhx3 and Pit-1, which are required for the development of PD thyrotrophs, clearly labeled the pituitary anlage. The common glycoprotein α-subunit (CGA) and TSH β-subunit (TSHB) genes were also detected in the pituitary anlage. In contrast, none of these genes were detected in the SV anlage. We then performed a microarray analysis and identified parvalbumin (Pvalb) as a marker for SV development. Because Pvalb expression was not detected in the pituitary anlage, no relationship was observed between the development of the SV and the pituitary gland. In contrast to embryos, Lhx3, Pit-1, CGA, and TSHB were all expressed in the adult SV. These results suggest that the morphological differentiation of SV occurs during the embryonic stage but that the functional differentiation into a seasonal sensor occurs in a later developmental stage.
Collapse
Affiliation(s)
- Ryosuke Maeda
- Laboratory of Animal Physiology (R.M., T.S., Y.N., T.Y.), Avian Bioscience Research Center (T.Y.), Graduate School of Bioagricultural Sciences, and Institute of Transformative Bio-Molecules (WPI-ITbM) (T.Y.), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Nippon Veterinary and Life Science University (N.N.), Kyonancho, Musashino, Tokyo 180-8602, Japan; and Division of Seasonal Biology (T.S.. T.Y.), National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Takayuki Shimo
- Laboratory of Animal Physiology (R.M., T.S., Y.N., T.Y.), Avian Bioscience Research Center (T.Y.), Graduate School of Bioagricultural Sciences, and Institute of Transformative Bio-Molecules (WPI-ITbM) (T.Y.), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Nippon Veterinary and Life Science University (N.N.), Kyonancho, Musashino, Tokyo 180-8602, Japan; and Division of Seasonal Biology (T.S.. T.Y.), National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Yusuke Nakane
- Laboratory of Animal Physiology (R.M., T.S., Y.N., T.Y.), Avian Bioscience Research Center (T.Y.), Graduate School of Bioagricultural Sciences, and Institute of Transformative Bio-Molecules (WPI-ITbM) (T.Y.), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Nippon Veterinary and Life Science University (N.N.), Kyonancho, Musashino, Tokyo 180-8602, Japan; and Division of Seasonal Biology (T.S.. T.Y.), National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Nobuhiro Nakao
- Laboratory of Animal Physiology (R.M., T.S., Y.N., T.Y.), Avian Bioscience Research Center (T.Y.), Graduate School of Bioagricultural Sciences, and Institute of Transformative Bio-Molecules (WPI-ITbM) (T.Y.), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Nippon Veterinary and Life Science University (N.N.), Kyonancho, Musashino, Tokyo 180-8602, Japan; and Division of Seasonal Biology (T.S.. T.Y.), National Institute for Basic Biology, Okazaki 444-8585, Japan
| | - Takashi Yoshimura
- Laboratory of Animal Physiology (R.M., T.S., Y.N., T.Y.), Avian Bioscience Research Center (T.Y.), Graduate School of Bioagricultural Sciences, and Institute of Transformative Bio-Molecules (WPI-ITbM) (T.Y.), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Nippon Veterinary and Life Science University (N.N.), Kyonancho, Musashino, Tokyo 180-8602, Japan; and Division of Seasonal Biology (T.S.. T.Y.), National Institute for Basic Biology, Okazaki 444-8585, Japan
| |
Collapse
|
33
|
Abstract
The endocrine hypothalamus constitutes those cells which project to the median eminence and secrete neurohormones into the hypophysial portal blood to act on cells of the anterior pituitary gland. The entire endocrine system is controlled by these peptides. In turn, the hypothalamic neuroendocrine cells are regulated by feedback signals from the endocrine glands and other circulating factors. The neuroendocrine cells are found in specific regions of the hypothalamus and are regulated by afferents from higher brain centers. Integrated function is clearly complex and the networks between and amongst the neuroendocrine cells allows fine control to achieve homeostasis. The entry of hormones and other factors into the brain, either via the cerebrospinal fluid or through fenestrated capillaries (in the basal hypothalamus) is important because it influences the extent to which feedback regulation may be imposed. Recent evidence of the passage of factors from the pars tuberalis and the median eminence casts a new layer in our understanding of neuroendocrine regulation. The function of neuroendocrine cells and the means by which pulsatile secretion is achieved is best understood for the close relationship between gonadotropin releasing hormone and luteinizing hormone, which is reviewed in detail. The secretion of other neurohormones is less rigid, so the relationship between hypothalamic secretion and the relevant pituitary hormones is more complex.
Collapse
Affiliation(s)
- I J Clarke
- Monash University, Department of Physiology, Clayton, Australia
| |
Collapse
|
34
|
Johnston JD, Skene DJ. 60 YEARS OF NEUROENDOCRINOLOGY: Regulation of mammalian neuroendocrine physiology and rhythms by melatonin. J Endocrinol 2015; 226:T187-98. [PMID: 26101375 DOI: 10.1530/joe-15-0119] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/17/2015] [Indexed: 12/15/2022]
Abstract
The isolation of melatonin was first reported in 1958. Since the demonstration that pineal melatonin synthesis reflects both daily and seasonal time, melatonin has become a key element of chronobiology research. In mammals, pineal melatonin is essential for transducing day-length information into seasonal physiological responses. Due to its lipophilic nature, melatonin is able to cross the placenta and is believed to regulate multiple aspects of perinatal physiology. The endogenous daily melatonin rhythm is also likely to play a role in the maintenance of synchrony between circadian clocks throughout the adult body. Pharmacological doses of melatonin are effective in resetting circadian rhythms if taken at an appropriate time of day, and can acutely regulate factors such as body temperature and alertness, especially when taken during the day. Despite the extensive literature on melatonin physiology, some key questions remain unanswered. In particular, the amplitude of melatonin rhythms has been recently associated with diseases such as type 2 diabetes mellitus but understanding of the physiological significance of melatonin rhythm amplitude remains poorly understood.
Collapse
Affiliation(s)
- Jonathan D Johnston
- Faculty of Health and Medical SciencesUniversity of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Debra J Skene
- Faculty of Health and Medical SciencesUniversity of Surrey, Guildford, Surrey GU2 7XH, UK
| |
Collapse
|
35
|
Bolborea M, Helfer G, Ebling FJP, Barrett P. Dual signal transduction pathways activated by TSH receptors in rat primary tanycyte cultures. J Mol Endocrinol 2015; 54:241-50. [PMID: 25878058 DOI: 10.1530/jme-14-0298] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Tanycytes play multiple roles in hypothalamic functions, including sensing peripheral nutrients and metabolic hormones, regulating neurosecretion and mediating seasonal cycles of reproduction and metabolic physiology. This last function reflects the expression of TSH receptors in tanycytes, which detect photoperiod-regulated changes in TSH secretion from the neighbouring pars tuberalis. The present overall aim was to determine the signal transduction pathway by which TSH signals in tanycytes. Expression of the TSH receptor in tanycytes of 10-day-old Sprague Dawley rats was observed by in situ hybridisation. Primary ependymal cell cultures prepared from 10-day-old rats were found by immunohistochemistry to express vimentin but not GFAP and by PCR to express mRNA for Dio2, Gpr50, Darpp-32 and Tsh receptors that are characteristic of tanycytes. Treatment of primary tanycyte/ependymal cultures with TSH (100 IU/l) increased cAMP as assessed by ELISA and induced a cAMP-independent increase in the phosphorylation of ERK1/2 as assessed by western blot analysis. Furthermore, TSH (100 IU/l) stimulated a 2.17-fold increase in Dio2 mRNA expression. We conclude that TSH signal transduction in cultured tanycytes signals via Gαs to increase cAMP and via an alternative G protein to increase phosphorylation of ERK1/2.
Collapse
Affiliation(s)
- Matei Bolborea
- Rowett Institute of Nutrition and Health University of Aberdeen, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK School of Life Sciences University of Nottingham Medical School, Nottingham NG7 2UH, UK Rowett Institute of Nutrition and Health University of Aberdeen, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK School of Life Sciences University of Nottingham Medical School, Nottingham NG7 2UH, UK
| | - Gisela Helfer
- Rowett Institute of Nutrition and Health University of Aberdeen, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK School of Life Sciences University of Nottingham Medical School, Nottingham NG7 2UH, UK
| | - Francis J P Ebling
- Rowett Institute of Nutrition and Health University of Aberdeen, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK School of Life Sciences University of Nottingham Medical School, Nottingham NG7 2UH, UK
| | - Perry Barrett
- Rowett Institute of Nutrition and Health University of Aberdeen, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK School of Life Sciences University of Nottingham Medical School, Nottingham NG7 2UH, UK
| |
Collapse
|
36
|
Christian HC, Imirtziadis L, Tortonese D. Ultrastructural changes in lactotrophs and folliculo-stellate cells in the ovine pituitary during the annual reproductive cycle. J Neuroendocrinol 2015; 27:277-84. [PMID: 25650820 DOI: 10.1111/jne.12261] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 01/30/2015] [Accepted: 01/30/2015] [Indexed: 11/26/2022]
Abstract
In seasonal mammals living in temperate zones, photoperiod regulates prolactin secretion, such that prolactin plasma concentrations peak during the summer months and are lowest during the winter. In sheep, a short-day breeder, circulating prolactin has important modulatory effects on the reproductive system via inhibitory actions on pituitary gonadotrophs and hypothalamic gonadotrophin-releasing hormone release. The exact cellular mechanisms that account for the chronic hypersecretion of prolactin during the summer is not known, although evidence supports an intrapituitary mechanism regulated by melatonin. Folliculo-stellate (FS) cells are non-endocrine cells that play a crucial role in paracrine communication within the pituitary and produce factors controlling prolactin and gonadotrophin release. The present study examined the morphology of the FS and lactotroph cell populations and their distribution in the sheep pituitary during the annual reproductive cycle. Ovine pituitary glands were collected in the winter (breeding season; BS) and summer (nonbreeding season; NBS) and were prepared for quantitative electron microscopy to assess the effects of season on FS and lactotroph cell density, morphology and distribution, as well as on junctional contacts between cells. It was found that lactotrophs in the NBS are larger in size and contain more numerous PRL granules than lactotrophs in the BS. FS cells were also larger in the NBS compared to BS and showed altered morphology such that, in the BS, long cell processes surrounded clusters of adjacent secretory cells. Although no significant change in the number of junctions was observed between lactotrophs and FS cells, or lactotrophs and gonadotrophs, there was a significant increase in the number of adherens junctions between lactotrophs and between FS cells. These findings demonstrate seasonal plasticity in the morphology of lactotrophs and FS cells that reflect changes in PRL secretion.
Collapse
Affiliation(s)
- H C Christian
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | | | | |
Collapse
|
37
|
Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells. PLoS One 2015; 10:e0117967. [PMID: 25714375 PMCID: PMC4340921 DOI: 10.1371/journal.pone.0117967] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 12/15/2014] [Indexed: 12/15/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.
Collapse
|
38
|
Ikegami K, Liao XH, Hoshino Y, Ono H, Ota W, Ito Y, Nishiwaki-Ohkawa T, Sato C, Kitajima K, Iigo M, Shigeyoshi Y, Yamada M, Murata Y, Refetoff S, Yoshimura T. Tissue-specific posttranslational modification allows functional targeting of thyrotropin. Cell Rep 2014; 9:801-10. [PMID: 25437536 PMCID: PMC4251493 DOI: 10.1016/j.celrep.2014.10.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/04/2014] [Accepted: 09/30/2014] [Indexed: 10/24/2022] Open
Abstract
Thyroid-stimulating hormone (TSH; thyrotropin) is a glycoprotein secreted from the pituitary gland. Pars distalis-derived TSH (PD-TSH) stimulates the thyroid gland to produce thyroid hormones (THs), whereas pars tuberalis-derived TSH (PT-TSH) acts on the hypothalamus to regulate seasonal physiology and behavior. However, it had not been clear how these two TSHs avoid functional crosstalk. Here, we show that this regulation is mediated by tissue-specific glycosylation. Although PT-TSH is released into the circulation, it does not stimulate the thyroid gland. PD-TSH is known to have sulfated biantennary N-glycans, and sulfated TSH is rapidly metabolized in the liver. In contrast, PT-TSH has sialylated multibranched N-glycans; in the circulation, it forms the macro-TSH complex with immunoglobulin or albumin, resulting in the loss of its bioactivity. Glycosylation is fundamental to a wide range of biological processes. This report demonstrates its involvement in preventing functional crosstalk of signaling molecules in the body.
Collapse
Affiliation(s)
- Keisuke Ikegami
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Xiao-Hui Liao
- Department of Medicine, The University of Chicago, Chicago, IL 60637, USA
| | - Yuta Hoshino
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Hiroko Ono
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Wataru Ota
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Yuka Ito
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Taeko Nishiwaki-Ohkawa
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Chihiro Sato
- Laboratory of Animal Cell Function, Bioscience and Biotechnology Center and Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Ken Kitajima
- Laboratory of Animal Cell Function, Bioscience and Biotechnology Center and Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Masayuki Iigo
- Department of Applied Biological Chemistry, Faculty of Agriculture, C-Bio, and CORE, Utsunomiya University, 350 Mine-machi, Utsunomiya 321-8505, Japan
| | - Yasufumi Shigeyoshi
- Department of Anatomy and Neurobiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan
| | - Masanobu Yamada
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
| | - Yoshiharu Murata
- Department of Genetics, Research Institute of Environmental Medicine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
| | - Samuel Refetoff
- Department of Medicine, The University of Chicago, Chicago, IL 60637, USA; Department of Pediatrics and Committee on Genetics, The University of Chicago, Chicago, IL 60637, USA.
| | - Takashi Yoshimura
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; Institute of Transformative Bio-Molecules (WPI-ITbM), 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, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan.
| |
Collapse
|
39
|
Wood S, Loudon A. Clocks for all seasons: unwinding the roles and mechanisms of circadian and interval timers in the hypothalamus and pituitary. J Endocrinol 2014; 222:R39-59. [PMID: 24891434 PMCID: PMC4104039 DOI: 10.1530/joe-14-0141] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Adaptation to the environment is essential for survival, in all wild animal species seasonal variation in temperature and food availability needs to be anticipated. This has led to the evolution of deep-rooted physiological cycles, driven by internal clocks, which can track seasonal time with remarkable precision. Evidence has now accumulated that a seasonal change in thyroid hormone (TH) availability within the brain is a crucial element. This is mediated by local control of TH-metabolising enzymes within specialised ependymal cells lining the third ventricle of the hypothalamus. Within these cells, deiodinase type 2 enzyme is activated in response to summer day lengths, converting metabolically inactive thyroxine (T4) to tri-iodothyronine (T3). The availability of TH in the hypothalamus appears to be an important factor in driving the physiological changes that occur with season. Remarkably, in both birds and mammals, the pars tuberalis (PT) of the pituitary gland plays an essential role. A specialised endocrine thyrotroph cell (TSH-expressing) is regulated by the changing day-length signal, leading to activation of TSH by long days. This acts on adjacent TSH-receptors expressed in the hypothalamic ependymal cells, causing local regulation of deiodinase enzymes and conversion of TH to the metabolically active T3. In mammals, the PT is regulated by the nocturnal melatonin signal. Summer-like melatonin signals activate a PT-expressed clock-regulated transcription regulator (EYA3), which in turn drives the expression of the TSHβ sub-unit, leading to a sustained increase in TSH expression. In this manner, a local pituitary timer, driven by melatonin, initiates a cascade of molecular events, led by EYA3, which translates to seasonal changes of neuroendocrine activity in the hypothalamus. There are remarkable parallels between this PT circuit and the photoperiodic timing system used in plants, and while plants use different molecular signals (constans vs EYA3) it appears that widely divergent organisms probably obey a common set of design principles.
Collapse
Affiliation(s)
- Shona Wood
- Faculty of Life SciencesUniversity of Manchester, Manchester M13 9PT, UK
| | - Andrew Loudon
- Faculty of Life SciencesUniversity of Manchester, Manchester M13 9PT, UK
| |
Collapse
|
40
|
Majumdar G, Yadav G, Rani S, Kumar V. A photoperiodic molecular response in migratory redheaded bunting exposed to a single long day. Gen Comp Endocrinol 2014; 204:104-13. [PMID: 24837606 DOI: 10.1016/j.ygcen.2014.04.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 03/21/2014] [Accepted: 04/03/2014] [Indexed: 10/25/2022]
Abstract
A long day response is triggered by the activation of EYA3 (eyes absent 3) and TSH-β (thyroid stimulating hormone beta subunit) genes in the pars tuberalis (PT). However, protein products of these genes are not yet shown in the hypothalamus of a photoperiodic species. Therefore, using the 'first long day paradigm', EYA3 and TSH-β along with c-FOS and GnRH peptides were immunohistochemically localized and measured in the hypothalamus of photoperiodic redheaded buntings that were maintained on short days (SD, LD 8/16) and subjected to one full long day (LD, LD 16/8). Following morning light remained turned off, and birds were sacrificed in the first hour of the day. Brains were collected and processed for immunohistochemistry of peptides. FOS-lir and GnRH-lir cells were significantly higher in the preoptic area (POA) in LD than in SD, which indicated photoperiod induced neuronal activation and downstream effects, respectively, under LD. In LD, EYA3-lir cells were significantly increased in septal lateralis (SL) with fibres extending to sub-septal organ (SSO); EYA3 fibres were very dense in median eminence. Similarly, there were significantly increased TSH-β-lir cells in the ventricular region with much abundance in the PT and TSH-β-lir fibres in the SSO (extending up to SL), inferior hypothalamic nucleus (IH) and infundibular nucleus (IN) in LD birds. Elevated EYA3, TSH-α and TSH-β mRNA levels further confirmed photoperiodic induction at the transcriptional level in buntings on the first long day. These are the first results showing localization of photoperiodically induced peptides in the hypothalamus of a songbird species, the redheaded bunting.
Collapse
Affiliation(s)
- Gaurav Majumdar
- DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Delhi, Delhi 110 007, India
| | - Garima Yadav
- DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Lucknow, Lucknow 226 007, India
| | - Sangeeta Rani
- DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Lucknow, Lucknow 226 007, India
| | - Vinod Kumar
- DST-IRHPA Center for Excellence in Biological Rhythms Research, Department of Zoology, University of Delhi, Delhi 110 007, India.
| |
Collapse
|
41
|
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.
Collapse
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
| |
Collapse
|
42
|
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.
Collapse
Affiliation(s)
- Keisuke Ikegami
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | | |
Collapse
|
43
|
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.
Collapse
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
| |
Collapse
|
44
|
Adamah-Biassi EB, Zhang Y, Jung H, Vissapragada S, Miller RJ, Dubocovich ML. Distribution of MT1 melatonin receptor promoter-driven RFP expression in the brains of BAC C3H/HeN transgenic mice. J Histochem Cytochem 2014; 62:70-84. [PMID: 24051358 PMCID: PMC3873804 DOI: 10.1369/0022155413507453] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/04/2013] [Indexed: 12/29/2022] Open
Abstract
The pineal hormone melatonin activates two G-protein coupled receptors (MT1 and MT2) to regulate in part biological functions. The MT1 and MT2 melatonin receptors are heterogeneously distributed in the mammalian brain including humans. In the mouse, only a few reports have assessed the expression of the MT1 melatonin receptor expression using 2-iodomelatonin binding, in situ hybridization and/or polymerase chain reaction (PCR). Here, we described a transgenic mouse in which red fluorescence protein (RFP) is expressed under the control of the endogenous MT1 promoter, by inserting RFP cDNA at the start codon of MTNR1a gene within a bacterial artificial chromosome (BAC) and expressing this construct as a transgene. The expression of RFP in the brain of this mouse was examined either directly under a fluorescent microscope or immunohistochemically using an antibody against RFP (RFP-MT1). RFP-MT1 expression was observed in many brain regions including the subcommissural organ, parts of the ependyma lining the lateral and third ventricles, the aqueduct, the hippocampus, the cerebellum, the pars tuberalis, the habenula and the habenula commissure. This RFP-MT1 transgenic model provides a unique tool for studying the distribution of the MT1 receptor in the brain of mice, its cell-specific expression and its function in vivo.
Collapse
Affiliation(s)
- E B Adamah-Biassi
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo NY (EBAB, YZ, SV, MLD)
| | | | | | | | | | | |
Collapse
|
45
|
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.
Collapse
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
| | | |
Collapse
|
46
|
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.
Collapse
Affiliation(s)
- Takashi Yoshimura
- Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
| |
Collapse
|
47
|
Aizawa S, Sakata I, Nagasaka M, Higaki Y, Sakai T. Negative regulation of neuromedin U mRNA expression in the rat pars tuberalis by melatonin. PLoS One 2013; 8:e67118. [PMID: 23843987 PMCID: PMC3699551 DOI: 10.1371/journal.pone.0067118] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/15/2013] [Indexed: 11/19/2022] Open
Abstract
The pars tuberalis (PT) is part of the anterior pituitary gland surrounding the median eminence as a thin cell layer. The characteristics of PT differ from those of the pars distalis (PD), such as cell composition and gene expression, suggesting that the PT has a unique physiological function compared to the PD. Because the PT highly expresses melatonin receptor type 1, it is considered a mediator of seasonal and/or circadian signals of melatonin. Expression of neuromedin U (NMU) that is known to regulate energy balance has been previously reported in the rat PT; however, the regulatory mechanism of NMU mRNA expression and secretion in the PT are still obscure. In this study, we examined both the diurnal change of NMU mRNA expression in the rat PT and the effects of melatonin on NMU in vivo. In situ hybridization and quantitative PCR analysis of laser microdissected PT samples revealed that NMU mRNA expression in the PT has diurnal variation that is high during the light phase and low during the dark phase. Furthermore, melatonin administration significantly suppressed NMU mRNA expression in the PT in vivo. On the other hand, 48 h fasting did not have an effect on PT-NMU mRNA expression, and the diurnal change of NMU mRNA expression was maintained. We also found the highest expression of neuromedin U receptor type 2 (NMUR2) mRNA in the third ventricle ependymal cell layer, followed by the arcuate nucleus and the spinal cord. These results suggest that NMU mRNA expression in the PT is downregulated by melatonin during the dark phase and shows diurnal change. Considering that NMU mRNA in the PT showed the highest expression level in the brain, PT-NMU may act on NMUR2 in the brain, especially in the third ventricle ependymal cell layer, with a circadian rhythm.
Collapse
Affiliation(s)
- Sayaka Aizawa
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| | - Ichiro Sakata
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| | - Mai Nagasaka
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| | - Yuriko Higaki
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| | - Takafumi Sakai
- Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Sakuraku, Saitama, Japan
| |
Collapse
|
48
|
Hodson DJ, Townsend J, Tortonese DJ. Cells co-expressing luteinising hormone and thyroid-stimulating hormone are present in the ovine pituitary pars distalis but not the pars tuberalis: implications for the control of endogenous circannual rhythms of prolactin. Neuroendocrinology 2013; 97:355-62. [PMID: 23548370 DOI: 10.1159/000350790] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 03/18/2013] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS A mammalian circannual pacemaker responsible for regulating the seasonal pattern of prolactin has been recently described in sheep. This pacemaker resides within the pars tuberalis, an area of the pituitary gland that densely expresses melatonin receptors. However, the chemical identity of the cell type which acts as the pacemaker remains elusive. Mathematical-modelling approaches have established that this cell must be responsive to the static melatonin signal as well as prolactin negative feedback. Considering that in sheep the gonadotroph is the only cell in the pars tuberalis which expresses the prolactin receptor, and that in other photoperiodic species the thyrotroph is the only cell expressing the melatonin receptor in this tissue, a cell type which expresses both proteins would fulfil the theoretical criteria of a circannual pacemaker. METHODS Pituitary glands were obtained from female sheep under short days (breeding season) and long days (non-breeding season) and double immunofluorescent staining was conducted to determine the prevalence of bi-hormonal cells in the pars distalis and pars tuberalis using specific antibodies to luteinising hormone-β and thyroid-stimulating hormone-β. RESULTS The results reveal that whilst such a bihormonal cell is clearly present in the pars distalis and constitute 4% of the gonadotroph population in this region, the same cell type is completely absent from the pars tuberalis even though LH gonadotrophs are abundantly expressed. CONCLUSIONS Based on these findings, together with existing data, we are able to propose an alternative model where the gonadotroph itself is controlled indirectly by neighbouring melatonin responsive cells, allowing it to act as a pacemaker.
Collapse
Affiliation(s)
- David J Hodson
- Department of Anatomy, Faculty of Medical and Veterinary Sciences, University of Bristol, Bristol, UK
| | | | | |
Collapse
|
49
|
West A, Dupré SM, Yu L, Paton IR, Miedzinska K, McNeilly AS, Davis JRE, Burt DW, Loudon ASI. Npas4 is activated by melatonin, and drives the clock gene Cry1 in the ovine pars tuberalis. Mol Endocrinol 2013; 27:979-89. [PMID: 23598442 PMCID: PMC3689899 DOI: 10.1210/me.2012-1366] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Seasonal mammals integrate changes in the duration of nocturnal melatonin secretion to drive annual physiologic cycles. Melatonin receptors within the proximal pituitary region, the pars tuberalis (PT), are essential in regulating seasonal neuroendocrine responses. In the ovine PT, melatonin is known to influence acute changes in transcriptional dynamics coupled to the onset (dusk) and offset (dawn) of melatonin secretion, leading to a potential interval-timing mechanism capable of decoding changes in day length (photoperiod). Melatonin offset at dawn is linked to cAMP accumulation, which directly induces transcription of the clock gene Per1. The rise of melatonin at dusk induces a separate and distinct cohort, including the clock-regulated genes Cry1 and Nampt, but little is known of the up-stream mechanisms involved. Here, we used next-generation sequencing of the ovine PT transcriptome at melatonin onset and identified Npas4 as a rapidly induced basic helix-loop-helix Per-Arnt-Sim domain transcription factor. In vivo we show nuclear localization of NPAS4 protein in presumptive melatonin target cells of the PT (α-glycoprotein hormone-expressing cells), whereas in situ hybridization studies identified acute and transient expression in the PT of Npas4 in response to melatonin. In vitro, NPAS4 forms functional dimers with basic helix loop helix-PAS domain cofactors aryl hydrocarbon receptor nuclear translocator (ARNT), ARNT2, and ARNTL, transactivating both Cry1 and Nampt ovine promoter reporters. Using a combination of 5′-deletions and site-directed mutagenesis, we show NPAS4-ARNT transactivation to be codependent upon two conserved central midline elements within the Cry1 promoter. Our data thus reveal NPAS4 as a candidate immediate early-response gene in the ovine PT, driving molecular responses to melatonin.
Collapse
Affiliation(s)
- A West
- University of Manchester, Manchester M13 9PT, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
50
|
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
| |
Collapse
|