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Appenroth D, Cázarez-Márquez F. Seasonal food intake and energy balance: Neuronal and non-neuronal control mechanisms. Neuropharmacology 2024; 257:110050. [PMID: 38914372 DOI: 10.1016/j.neuropharm.2024.110050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 06/05/2024] [Accepted: 06/21/2024] [Indexed: 06/26/2024]
Abstract
Animals inhabiting temperate and high latitudes undergo drastic seasonal changes in energy storage, facilitated by changes in food intake and body mass. Those seasonal changes in the animal's biology are not mere consequences of environmental energy availability but are anticipatory responses to the energetic requirements of the upcoming season and are actively timed by tracking the annual progression in photoperiod. In this review, we discuss how photoperiod is used to control energy balance seasonally and how this is distinct from energy homeostasis. Most notably, we suggest that photoperiodic control of food intake and body mass does not originate from the arcuate nucleus, as for homeostatic appetite control, but is rather to be found in hypothalamic tanycytes. Tanycytes are specialized ependymal cells lining the third ventricle, which can sense metabolites from the cerebrospinal fluid (e.g. glucose) and can control access of circulating signals to the brain. They are also essential in conveying time-of-year information by integrating photoperiod and altering hypothalamic thyroid metabolism, a feature that is conserved in seasonal vertebrates and connects to seasonal breeding and metabolism. We also discuss how homeostatic feedback signals are handled during times of rapid energetic transitions. Studies on leptin in seasonal mammals suggest a seasonal shift in central sensitivity and blood-brain transport, which might be facilitated by tanycytes. This article is part of the Special Issue on "Food intake and feeding states".
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Affiliation(s)
- Daniel Appenroth
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology & Physiology, Arctic & Marine Biology, BFE, UiT - Arctic University of Norway, Tromsø, Norway.
| | - Fernando Cázarez-Márquez
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology & Physiology, Arctic & Marine Biology, BFE, UiT - Arctic University of Norway, Tromsø, Norway
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2
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Miyagawa T, Tanaka S, Shimada M, Sakai N, Tanida K, Kotorii N, Kotorii T, Ariyoshi Y, Hashizume Y, Ogi K, Hiejima H, Kanbayashi T, Imanishi A, Ikegami A, Kamei Y, Hida A, Wada Y, Miyamoto M, Takami M, Kondo H, Tamura Y, Taniyama Y, Omata N, Mizuno T, Moriya S, Furuya H, Kato M, Kato K, Ishigooka J, Tsuruta K, Chiba S, Yamada N, Okawa M, Hirata K, Kuroda K, Kume K, Uchimura N, Kitada M, Kodama T, Inoue Y, Nishino S, Mishima K, Tokunaga K, Honda M. A rare genetic variant in the cleavage site of prepro-orexin is associated with idiopathic hypersomnia. NPJ Genom Med 2022; 7:29. [PMID: 35414074 PMCID: PMC9005711 DOI: 10.1038/s41525-022-00298-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 03/04/2022] [Indexed: 11/08/2022] Open
Abstract
Idiopathic hypersomnia (IH) is a rare, heterogeneous sleep disorder characterized by excessive daytime sleepiness. In contrast to narcolepsy type 1, which is a well-defined type of central disorders of hypersomnolence, the etiology of IH is poorly understood. No susceptibility loci associated with IH have been clearly identified, despite the tendency for familial aggregation of IH. We performed a variation screening of the prepro-orexin/hypocretin and orexin receptors genes and an association study for IH in a Japanese population, with replication (598 patients and 9826 controls). We identified a rare missense variant (g.42184347T>C; p.Lys68Arg; rs537376938) in the cleavage site of prepro-orexin that was associated with IH (minor allele frequency of 1.67% in cases versus 0.32% in controls, P = 2.7 × 10-8, odds ratio = 5.36). Two forms of orexin (orexin-A and -B) are generated from cleavage of one precursor peptide, prepro-orexin. The difference in cleavage efficiency between wild-type (Gly-Lys-Arg; GKR) and mutant (Gly-Arg-Arg; GRR) peptides was examined by assays using proprotein convertase subtilisin/kexin (PCSK) type 1 and PCSK type 2. In both PCSK1 and PCSK2 assays, the cleavage efficiency of the mutant peptide was lower than that of the wild-type peptide. We also confirmed that the prepro-orexin peptides themselves transmitted less signaling through orexin receptors than mature orexin-A and orexin-B peptides. These results indicate that a subgroup of IH is associated with decreased orexin signaling, which is believed to be a hallmark of narcolepsy type 1.
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Affiliation(s)
- Taku Miyagawa
- Sleep Disorders Project, Department of Psychiatry and Behavioral Sciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
| | - Susumu Tanaka
- Department of Anatomy, Faculty of Medicine, Kansai Medical University, Osaka, Japan
| | - Mihoko Shimada
- Sleep Disorders Project, Department of Psychiatry and Behavioral Sciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Genome Medical Science Project (Toyama), National Center for Global Health and Medicine, Tokyo, Japan
| | - Noriaki Sakai
- Sleep and Circadian Neurobiology Laboratory, School of Medicine, Stanford University, Stanford, CA, USA
| | - Kotomi Tanida
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Nozomu Kotorii
- Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
- Kotorii Isahaya Hospital, Nagasaki, Japan
| | | | | | - Yuji Hashizume
- Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
| | - Kimihiro Ogi
- Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
| | - Hiroshi Hiejima
- Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
| | - Takashi Kanbayashi
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki, Japan
- Ibaraki Prefectural Medical Center of Psychiatry, Ibaraki, Japan
| | - Aya Imanishi
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
| | | | - Yuichi Kamei
- Department of Laboratory Medicine, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan
- Kamisuwa Hospital, Nagano, Japan
| | - Akiko Hida
- Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Yamato Wada
- Department of Psychiatry, Hannan Hospital, Osaka, Japan
| | | | - Masanori Takami
- Department of Psychiatry, Shiga University of Medical Science, Shiga, Japan
| | - Hideaki Kondo
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki, Japan
| | - Yoshiyuki Tamura
- Department of Psychiatry and Neurology, Asahikawa Medical University, Hokkaido, Japan
| | - Yukari Taniyama
- Department of Neurology, Junwakai Memorial Hospital, Miyazaki, Japan
| | - Naoto Omata
- Department of Nursing, Faculty of Health Science, Fukui Health Science University, Fukui, Japan
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Tomoyuki Mizuno
- Department of Neuropsychiatry, Faculty of Medical Sciences, University of Fukui, Fukui, Japan
| | - Shunpei Moriya
- Department of Psychiatry, Tokyo Women's Medical University School of Medicine, Tokyo, Japan
| | - Hirokazu Furuya
- Department of Neurology, Neuro-Muscular Center, National Omuta Hospital, Fukuoka, Japan
- Department of Neurology, Kochi Medical School, Kochi University, Kochi, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Yamagata University Faculty of Medicine, Yamagata, Japan
- Department of Pediatrics, Showa University School of Medicine, Tokyo, Japan
| | - Kayoko Kato
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Kazuhito Tsuruta
- Department of Neurology, Junwakai Memorial Hospital, Miyazaki, Japan
| | - Shigeru Chiba
- Department of Psychiatry and Neurology, Asahikawa Medical University, Hokkaido, Japan
| | - Naoto Yamada
- Department of Psychiatry, Shiga University of Medical Science, Shiga, Japan
| | - Masako Okawa
- Department of Sleep Medicine, Shiga University of Medical Science, Shiga, Japan
- Japan Foundation for Neuroscience and Mental Health, Tokyo, Japan
- Department of Somnology, Tokyo Medical University, Tokyo, Japan
| | - Koichi Hirata
- Department of Neurology, Dokkyo Medical University, Tochigi, Japan
| | - Kenji Kuroda
- Department of Psychiatry, Hannan Hospital, Osaka, Japan
| | - Kazuhiko Kume
- Sleep Center, Kuwamizu Hospital, Kumamoto, Japan
- Department of Stem Cell Biology, Institute of Molecular Genetics and Embryology, Kumamoto University, Kumamoto, Japan
- Department of Neuropharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Aichi, Japan
| | - Naohisa Uchimura
- Department of Neuropsychiatry, Kurume University School of Medicine, Fukuoka, Japan
| | - Masaaki Kitada
- Department of Anatomy, Faculty of Medicine, Kansai Medical University, Osaka, Japan
| | - Tohru Kodama
- Sleep Disorders Project, Department of Psychiatry and Behavioral Sciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
| | - Yuichi Inoue
- Department of Somnology, Tokyo Medical University, Tokyo, Japan
- Yoyogi Sleep Disorder Center, Neuropsychiatric Research Institute, Tokyo, Japan
| | - Seiji Nishino
- Sleep and Circadian Neurobiology Laboratory, School of Medicine, Stanford University, Stanford, CA, USA
| | - Kazuo Mishima
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Ibaraki, Japan
- Department of Neuropsychiatry, Akita University Graduate School of Medicine, Akita, Japan
- Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Katsushi Tokunaga
- Department of Human Genetics, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Genome Medical Science Project (Toyama), National Center for Global Health and Medicine, Tokyo, Japan
| | - Makoto Honda
- Sleep Disorders Project, Department of Psychiatry and Behavioral Sciences, Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan
- Seiwa Hospital, Institute of Neuropsychiatry, Tokyo, Japan
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Liu H, He Y, Beck J, da Silva Teixeira S, Harrison K, Xu Y, Sisley S. Defining vitamin D receptor expression in the brain using a novel VDR Cre mouse. J Comp Neurol 2021; 529:2362-2375. [PMID: 33368246 DOI: 10.1002/cne.25100] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 12/10/2020] [Accepted: 12/16/2020] [Indexed: 12/15/2022]
Abstract
Vitamin D action has been linked to several diseases regulated by the brain including obesity, diabetes, autism, and Parkinson's. However, the location of the vitamin D receptor (VDR) in the brain is not clear due to conflicting reports. We found that two antibodies previously published as specific in peripheral tissues are not specific in the brain. We thus created a new knockin mouse with cre recombinase expression under the control of the endogenous VDR promoter (VDRCre ). We demonstrated that the cre activity in the VDRCre mouse brain (as reported by a cre-dependent tdTomato expression) is highly overlapping with endogenous VDR mRNAs. These VDR-expressing cells were enriched in multiple brain regions including the cortex, amygdala, caudate putamen, and hypothalamus among others. In the hypothalamus, VDR partially colocalized with vasopressin, oxytocin, estrogen receptor-α, and β-endorphin to various degrees. We further functionally validated our model by demonstrating that the endogenous VDR agonist 1,25-dihydroxyvitamin D activated all tested tdTomato+ neurons in the paraventricular hypothalamus but had no effect on neurons without tdTomato fluorescence. Thus, we have generated a new mouse tool that allows us to visualize VDR-expressing cells and to characterize their functions.
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Affiliation(s)
- Hailan Liu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Department of Metabolism and Endocrinology, Metabolic Syndrome Research Center, Key Laboratory of Diabetes Immunology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yang He
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Jessie Beck
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Silvania da Silva Teixeira
- Department of Pediatrics, Section of Nutrition, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA
| | - Keisha Harrison
- Department of Food Science and Technology, Oregon State University, Corvallis, Oregon, USA
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Stephanie Sisley
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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4
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Helfer G, Stevenson TJ. Pleiotropic effects of proopiomelanocortin and VGF nerve growth factor inducible neuropeptides for the long-term regulation of energy balance. Mol Cell Endocrinol 2020; 514:110876. [PMID: 32473184 DOI: 10.1016/j.mce.2020.110876] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 12/16/2022]
Abstract
Seasonal rhythms in energy balance are well documented across temperate and equatorial zones animals. The long-term regulated changes in seasonal physiology consists of a rheostatic system that is essential to successful time annual cycles in reproduction, hibernation, torpor, and migration. Most animals use the annual change in photoperiod as a reliable and robust environmental cue to entrain endogenous (i.e. circannual) rhythms. Research over the past few decades has predominantly examined the role of first order neuroendocrine peptides for the rheostatic changes in energy balance. These anorexigenic and orexigenic neuropeptides in the arcuate nucleus include neuropeptide y (Npy), agouti-related peptide (Agrp), cocaine and amphetamine related transcript (Cart) and pro-opiomelanocortin (Pomc). Recent studies also indicate that VGF nerve growth factor inducible (Vgf) in the arcuate nucleus is involved in the seasonal regulation of energy balance. In situ hybridization, qPCR and RNA-sequencing studies have identified that Pomc expression across fish, avian and mammalian species, is a neuroendocrine marker that reflects seasonal energetic states. Here we highlight that long-term changes in arcuate Pomc and Vgf expression is conserved across species and may provide rheostatic regulation of seasonal energy balance.
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Affiliation(s)
- Gisela Helfer
- Faculty of Life Sciences, University of Bradford, Bradford, UK
| | - Tyler J Stevenson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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5
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Cázarez-Márquez F, Laran-Chich MP, Klosen P, Kalsbeek A, Simonneaux V. RFRP3 increases food intake in a sex-dependent manner in the seasonal hamster Phodopus sungorus. J Neuroendocrinol 2020; 32:e12845. [PMID: 32291844 DOI: 10.1111/jne.12845] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/11/2020] [Accepted: 03/12/2020] [Indexed: 12/15/2022]
Abstract
In addition to its regulatory role in luteinising hormone secretion, Rfamide-related peptide 3 (RFRP3) has also been reported to modulate food intake in several mammalian species. Djungarian hamsters (Phodopus sungorus), similar to other seasonal mammals, display a remarkable inhibition of RFRP3 expression in winter short-day conditions, associated with decreased food intake and bodyweight. This species is therefore a valuable model for assessing whether RFRP3 might be involved in the seasonal control of feeding behaviour and investigating its possible brain targets. We found that, although both male and female animals exhibit the same robust reduction in Rfrp expression in short- (SD) compared to long-day (LD) conditions, acute central administration of RFRP3 displays sex-dependent effects on food intake. RFRP3 increased food intake in female hamsters in SD or in LD dioestrus, but not in LD pro-oestrus, indicating that the orexigenic effect of RFRP3 is observed in conditions of low circulating oestradiol levels. In male hamsters, food intake was not changed by acute injections of RFRP3, regardless of whether animals were in SD or LD conditions. Analysing the gene expression of various metabolic neuropeptides in the brain of RFRP3-injected Djungarian hamsters revealed that Npy expression was increased in female but not in male animals. The present study suggests that, in Djungarian hamsters, RFRP3 exhibits a sex-dependent orexigenic effect possibly by inducing increased Npy expression.
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Affiliation(s)
- Fernando Cázarez-Márquez
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
- Netherlands Institute for Neuroscience (NIN), Amsterdam, The Netherlands
- Laboratory of Endocrinology, Amsterdam UMC, Amsterdam Gastroenterology & Metabolism, University of Amsterdam, Amsterdam, The Netherlands
| | | | - Paul Klosen
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience (NIN), Amsterdam, The Netherlands
- Laboratory of Endocrinology, Amsterdam UMC, Amsterdam Gastroenterology & Metabolism, University of Amsterdam, Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Valérie Simonneaux
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
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6
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Seddon RJ, Hews DK. Melanization, α-melanocyte stimulating hormone and steroid hormones in male western fence lizards from nine populations. Gen Comp Endocrinol 2020; 285:113287. [PMID: 31563645 DOI: 10.1016/j.ygcen.2019.113287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/29/2019] [Accepted: 09/22/2019] [Indexed: 02/05/2023]
Abstract
Hormones can mediate suites of correlated traits. Melanocortins regulate melanin synthesis and elements of the melanocortin system can directly, and indirectly, affect a number of other traits, such as stress reactivity. Trait correlations within the melanocortin system have been studied mainly in birds and mammals but less so in reptiles. We examined adult male western fence lizards (Sceloporus occidentalis) and if melanization was correlated with plasma levels of three hormones, including peptide hormone α-melanocyte stimulating hormone (α-MSH), testosterone and corticosterone, and ectoparasite loads. This lizard is darker at higher elevations in California, and we compared five high-elevation and four low-elevation populations during comparable periods of the breeding season at each site. We first validated use of an α-MSH assay kit with lizard plasma. Since Anolis carolinensis is one of the few species with published values for α-MSH plasma levels, we assayed both Anolis and Sceloporus plasma and compared hormone values to those we generated for Anolis to the publish values. We also evaluated effects of different methods of storing spiked plasma pools on resulting α-MSH concentrations. Plasma levels of α-MSH did not differ significantly, but some populations differed significantly in mean corticosterone and mean testosterone. Combining all individuals from the nine populations, we found that individual variation in α-MSH was not associated with individual variation in melanization, but levels of α-MSH were positively associated with plasma testosterone and negatively associated with corticosterone. The lack of association between individual levels of melanization and expression of most other traits differs from a growing number of within-population studies of melanization, and we discuss what differences in physiological mechanisms could produce different hypothetical patterns. Circulating levels of -MSH are only one element of the melanocortin system; in situ synthesis of α-MSH by the skin and the diversity of melanocortin receptors could also contribute to variation in traits mediated by the melanocortin system and should be examined.
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Affiliation(s)
- Ryan J Seddon
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
| | - Diana K Hews
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
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Meddeb E, Charni M, Ben Abdallah R, Raboudi F, Fattouch S. A molecular study of Tunisian populations of Dugesia sicula (Plathelminthes, Tricladida) through an identification of a set of genes. C R Biol 2019; 342:291-298. [PMID: 31786144 DOI: 10.1016/j.crvi.2019.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 10/30/2019] [Indexed: 10/25/2022]
Abstract
Cell regeneration is a natural repair of different types of tissue after an injury or a lesion, and is associated with asexual reproduction in some animals such as planarians. Its understanding and improvement could have repercussions for tissue repair and regeneration as far as humans are concerned. In this context, we have proceeded to an essential step, which is the identification of the genes involved in planarian regeneration in the model species. Dugesia sicula Lepori (D. sicula) is distributed around the Mediterranean Sea, and this population is found in most of Tunisian dams. The collection of identified genes is already known in other species. DjFoxG, DjPC2, DjotxA, and Cathepsin-D were identified by the PCR technique and their expression was confirmed by RT-PCR and in situ hybridization. DjFoxG gene, the FoxG1 homolog, is expressed throughout the planarian body, abundantly on stem cells. Consecutively, we choose a central nervous system (CNS) marker; the prohormone convertase 2 (DjPC2) gene. DjotxA was observed in the brain and especially in the region surrounding the eyes (visual cells). The regenerative cells of the gut of D. sicula were scored by the Cathepsin-D gene expression, which belongs to the aspartyl protease family. We found significant results through RT-PCR and In Situ Hybridization (ISH) techniques, confirming the expression of DjFoxG, DjPC2, DjotxA and Cathepsin-D genes in our specimens.
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Affiliation(s)
- Emna Meddeb
- Laboratory of Food and Molecular Biochemistry, National Institute of Applied Sciences and Technology (INSAT), University of Carthage, Zone Urbaine Nord, 1080 Tunis, Tunisia; Faculty of Sciences of Bizerte, University of Carthage, Tunis, Tunisia.
| | - Mohamed Charni
- Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia; College of Sciences and Humanities of Dawadmi, Shaqra University, Shaqra, Kingdom of Saudi Arabia
| | - Rim Ben Abdallah
- Laboratory of Food and Molecular Biochemistry, National Institute of Applied Sciences and Technology (INSAT), University of Carthage, Zone Urbaine Nord, 1080 Tunis, Tunisia; Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Faten Raboudi
- ISAJC, Bir El Bey, University of Tunis, Tunis, Tunisia
| | - Sami Fattouch
- Laboratory of Food and Molecular Biochemistry, National Institute of Applied Sciences and Technology (INSAT), University of Carthage, Zone Urbaine Nord, 1080 Tunis, Tunisia
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8
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Cázarez-Márquez F, Milesi S, Laran-Chich MP, Klosen P, Kalsbeek A, Simonneaux V. Kisspeptin and RFRP3 modulate body mass in Phodopus sungorus via two different neuroendocrine pathways. J Neuroendocrinol 2019; 31:e12710. [PMID: 30887598 DOI: 10.1111/jne.12710] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 03/09/2019] [Accepted: 03/14/2019] [Indexed: 01/15/2023]
Abstract
Many animals exhibit remarkable metabolic and reproductive adaptations to seasonal changes in their environment. When day length shortens, Djungarian hamsters (Phodopus sungorus) reduce their body weight and inhibit their reproductive activity, whereas the opposite occurs in springtime. These physiological adaptations are considered to depend on photoperiodic changes in hypothalamic genes encoding the peptides kisspeptin (Kp) and RFamide-related peptide 3 (RFRP3) for the control of reproduction, as well as pro-opiomelanocortin and somatostatin for metabolic regulation. The present study investigates the effect of Kp and RFRP3 on long-term body weight regulation, aiming to establish whether metabolic and reproductive hypothalamic networks may interact during adaptation to seasonal physiology. We found that chronic central administration of both Kp and RFRP3 in short photoperiod-adapted male Djungarian hamsters increased body weight, although via different pathways. The effect of Kp was dependent on testicular activity because castration prevented the body weight increase and was associated with an increase in pro-opiomelanocortin and neuropeptide Y expression. On the other hand, the orexigenic effect of RFRP3 was associated with an increase in circulating insulin and leptin levels, although it had no effect on any of the hypothalamic metabolic genes investigated, and did not change circulating levels of sex steroids. Notably, neither Kp, nor RFRP3 altered female hamster metabolic parameters. Thus, using a rodent model exhibiting seasonal changes in reproduction and metabolism, the present study demonstrates that, in addition to its role in the central control of reproduction, Kp also participates in body weight control in a sex-dependent manner via an anabolic action of testosterone. Conversely, RFRP3 affects body weight control in males mostly by acting on adiposity, with no overt effect on the reproductive system in both sexes.
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Affiliation(s)
- Fernando Cázarez-Márquez
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
- Netherlands Institute for Neuroscience (NIN), Amsterdam, The Netherlands
- Laboratory of Endocrinology, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Sebastien Milesi
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
| | | | - Paul Klosen
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience (NIN), Amsterdam, The Netherlands
- Laboratory of Endocrinology, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Valérie Simonneaux
- Institute of Cellular and Integrative Neurosciences (INCI), Strasbourg, France
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9
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Iyer M, Essner RA, Klingenberg B, Carter ME. Identification of discrete, intermingled hypocretin neuronal populations. J Comp Neurol 2018; 526:2937-2954. [PMID: 30019757 DOI: 10.1002/cne.24490] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Revised: 06/12/2018] [Accepted: 06/14/2018] [Indexed: 01/04/2023]
Abstract
Neurons in the lateral hypothalamic area that express hypocretin (Hcrt) neuropeptides help regulate many behaviors including wakefulness and reward seeking. These neurons project throughout the brain, including to neural populations that regulate wakefulness, such as the locus coeruleus (LC) and tuberomammilary nucleus (TMN), as well as to populations that regulate reward, such as the nucleus accumbens (NAc) and ventral tegmental area (VTA). To address the roles of Hcrt neurons in seemingly disparate behaviors, it has been proposed that Hcrt neurons can be anatomically subdivided into at least two distinct subpopulations: a "medial group" that projects to the LC and TMN, and a "lateral group" that projects to the NAc and VTA. Here, we use a dual retrograde tracer strategy to test the hypotheses that Hcrt neurons can be classified based on their downstream projections and medial/lateral location within the hypothalamus. We found that individual Hcrt neurons were significantly more likely to project to both the LC and TMN or to both the VTA and NAc than would be predicted by chance. In contrast, we found that Hcrt neurons that projected to the LC or TMN were mostly distinct from Hcrt neurons that projected to the VTA or NAc. Interestingly, these two populations of Hcrt neurons are intermingled within the hypothalamus and cannot be classified into medial or lateral groups. These results suggest that Hcrt neurons can be distinguished based on their downstream projections but are intermingled within the hypothalamus.
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Affiliation(s)
- Manasi Iyer
- Department of Biology, Williams College, Williamstown, Massachusetts.,Program in Neuroscience, Williams College, Williamstown, Massachusetts
| | - Rachel A Essner
- Department of Biology, Williams College, Williamstown, Massachusetts.,Program in Neuroscience, Williams College, Williamstown, Massachusetts
| | - Bernhard Klingenberg
- Department of Mathematics and Statistics, Williams College, Williamstown, Massachusetts
| | - Matthew E Carter
- Department of Biology, Williams College, Williamstown, Massachusetts.,Program in Neuroscience, Williams College, Williamstown, Massachusetts
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10
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Seddon RJ, Hews DK. Correlates of melanization in multiple high- and low-elevation populations of the lizard,Sceloporus occidentalis: Behavior, hormones, and parasites. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 327:481-492. [DOI: 10.1002/jez.2133] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/21/2017] [Accepted: 10/30/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J. Seddon
- Department of Biology; Indiana State University; Terre Haute Indiana
| | - Diana K. Hews
- Department of Biology; Indiana State University; Terre Haute Indiana
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11
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True C, Takahashi D, Kirigiti M, Lindsley SR, Moctezuma C, Arik A, Smith MS, Kievit P, Grove KL. Arcuate nucleus neuropeptide coexpression and connections to gonadotrophin-releasing hormone neurones in the female rhesus macaque. J Neuroendocrinol 2017; 29:10.1111/jne.12491. [PMID: 28561903 PMCID: PMC5523807 DOI: 10.1111/jne.12491] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 05/26/2017] [Accepted: 05/26/2017] [Indexed: 12/11/2022]
Abstract
The underlying hypothalamic neurocircuitry by which metabolism and feeding regulates reproductive function has been well-studied in the rodent; however, recent data have demonstrated significant neuroanatomical differences in the human brain. The present study had three objectives, centred on arcuate nucleus neuropeptides regulating feeding and reproduction: (i) to characterise coexpression patterns in the female nonhuman primate; (ii) to establish whether these neuronal populations make potential contacts with gonadotophin-releasing hormone (GnRH) neurones; and (iii) to determine whether these contacts differ between the low and high GnRH-releasing states of pre-puberty and adulthood, respectively. Female nonhuman primates have several coexpression patterns of hypothalamic neuropeptides that differ from those reported in rodents. Cocaine- and amphetamine-regulated transcript (CART) is not coexpressed with pro-opiomelanocortin but instead with neuropeptide Y (NPY). CART is also expressed in a subpopulation of kisspeptin cells in the nonhuman primate, similar to observations in humans but diverging from findings in rodents. Very few GnRH-expressing neurones received close appositions from double-labelled kisspeptin/CART fibres; however, both single-labelled kisspeptin and CART fibres were in frequent apposition with GnRH neurones, with no differences between prepubertal and adult animals. NPY/agouti-related peptide (AgRP) coexpressing fibres contacted significantly more GnRH neurones in prepubertal animals than adults, consistent with increased NPY and AgRP mRNA observed in prepubertal animals. The findings of the present study detail significant differences in arcuate nucleus neuropeptide coexpression in the monkey compared to the rodent and are consistent with the hypothesis that arcuate nucleus NPY/AgRP neurones play an inhibitory role in controlling GnRH neuronal regulation in the prepubertal primate.
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Affiliation(s)
- C True
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - D Takahashi
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - M Kirigiti
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - S R Lindsley
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - C Moctezuma
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - A Arik
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - M S Smith
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - P Kievit
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
| | - K L Grove
- Division of Diabetes, Obesity and Metabolism, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR, USA
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12
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Pauls D, Chen J, Reiher W, Vanselow JT, Schlosser A, Kahnt J, Wegener C. Peptidomics and processing of regulatory peptides in the fruit fly Drosophila. EUPA OPEN PROTEOMICS 2014. [DOI: 10.1016/j.euprot.2014.02.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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13
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Tang L, Ye H, Hong Q, Chen F, Wang Q, Xu L, Bu S, Liu Q, Ye M, Wang DW, Mai Y, Duan S. Meta-analyses between 18 candidate genetic markers and overweight/obesity. Diagn Pathol 2014; 9:56. [PMID: 24621099 PMCID: PMC4008255 DOI: 10.1186/1746-1596-9-56] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 03/04/2014] [Indexed: 01/09/2023] Open
Abstract
Aims The goal of our study is to investigate the associations between 18 candidate genetic markers and overweight/obesity. Methods A total of 72 eligible articles were retrieved from literature databases including PubMed, Embase, SpingerLink, Web of Science, Chinese National Knowledge Infrastructure (CNKI), and Wanfang. Meta-analyses of 18 genetic markers among 56,738 controls and 48,148 overweight/obese persons were done by Review Manager 5.0. Results Our results showed that SH2B1 rs7498665 polymorphism was significantly associated with the risk of overweight/obesity (overall odds ratio (OR) = 1.21, 95% confidence interval (CI) = 1.09-1.34, P = 0.0004). Increased risk of overweight/obesity was also observed in FAIM2 rs7138803 polymorphism (overall OR = 1.11, 95% CI = 1.01-1.22, P = 0.04). Conclusion Our meta-analyses have shown the important role of 2 polymorphisms (SH2B1 rs7498665 and FAIM2 rs7138803) in the development of overweight/obesity. This study highlighted the importance of above two candidate genes (SH2B1 and FAIM2) in the risk of overweight/obesity. Virtual slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2785487401176182.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Meng Ye
- Zhejiang Provincial Key Laboratory of Pathophysiology, School of Medicine, Ningbo University, 315211 Ningbo, Zhejiang, China.
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14
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Hiramoto K, Yamate Y, Kobayashi H, Ishii M, Sato EF, Inoue M. Ultraviolet B irradiation of the mouse eye induces pigmentation of the skin more strongly than does stress loading, by increasing the levels of prohormone convertase 2 and α-melanocyte-stimulating hormone. Clin Exp Dermatol 2013; 38:71-6. [PMID: 23252754 DOI: 10.1111/j.1365-2230.2012.04439.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND In previous studies, we made the unexpected finding that in mice, ultraviolet (UV)B irradiation of the eye increased the concentration of α-melanocyte-stimulating hormone (α-MSH) in plasma, and systemically stimulated epidermal melanocytes. AIMS To compare the extent of the pigmentation induced by social and restraint stress (which activate the hippocampus-pituitary system) with that induced by UVB irradiation. METHODS DBA/2 and sham-operated or hypophysectomized DBA/2 mice were subjected to local UVB exposure using a sunlamp directed at the eye, and two types of stress (social and restraint) were imposed. RESULTS UVB irradiation of the eye or exposure to stress loading both increased the number of Dopa-positive melanocytes in the epidermis, and hypophysectomy strongly inhibited the UVB-induced and stress-induced stimulation of melanocytes. Irradiation of the eye caused a much greater increase in dopamine than did the stress load. Both UVB eye irradiation and stress increased the blood levels of α-MSH and adrenocorticotropic hormone (ACTH). In addition, the increase in plasma α-MSH was greater in animals subjected to UVB eye irradiation than in those subjected to stress loading, whereas the reverse occurred for plasma ACTH. UVB irradiation to the eye and stress loading increased the expression of prohormone convertase (PC)1/3 and PC2 in the pituitary gland. The increase in expression of pituitary PC2 was greater in animals subjected to UVB eye irradiation than to stress, whereas no difference was seen between the two groups for the increase in PC1/3. CONCLUSIONS UVB eye irradiation exerts a stronger effect on pigmentation than stress loading, and is related to increased levels of α-MSH and PC2.
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Affiliation(s)
- K Hiramoto
- Department of Dermatology, Osaka City University Graduate School of Medicine, Japan.
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15
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Navarro M, Cubero I, Thiele TE. Decreased immunoreactivity of the polypeptide precursor pro-opiomelanocortin (POMC) and the prohormone convertase pc1/3 after chronic ethanol exposure in Sprague-Dawley rats. Alcohol Clin Exp Res 2013; 37:399-406. [PMID: 23050949 PMCID: PMC3543756 DOI: 10.1111/j.1530-0277.2012.01951.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 07/17/2012] [Indexed: 01/24/2023]
Abstract
BACKGROUND The melanocortin (MC) peptides and opioid peptide β-endorphin are cleaved from the polypeptide precursor pro-opiomelanocortin (POMC). POMC-derived peptides are generated by extensive posttranslational processing that involves several enzymes including prohormone convertase 1/3 and 2 (PC1/3 and PC2). Because ethanol (EtOH) decreases POMC mRNA levels, we determined whether the exposure to an EtOH-containing diet (ED) would significantly reduce central immunoreactivity (IR) of POMC, PC1/3, PC2, and β-endorphin. METHODS Male Sprague-Dawley rats were given 18 days of access to a normal rodent chow or a control diet (CD), or short-term (4 days) or long-term (18 days) access to an ED. At the end of the study, rats were perfused with 4% paraformaldehyde, and their brains were sectioned into sets for processing with POMC, PC1/3, PC2, and β-endorphin IR. RESULTS Rats exposed to an ED for 18 days (ED18) exhibited significant reductions of POMC and PC1/3 IR in the arcuate nucleus of the hypothalamus (Arc) relative to rats pair-fed a CD. On the other hand, rats exposed to an ED did not show any changes of central β-endorphin or PC2 IR relative to rats pair-fed a CD, regardless of length of exposure. Because there were no differences in body weights or caloric intake between the CD and ED groups, reductions of POMC and PC1/3 IR in ED-treated rats are best explained by EtOH exposure rather than altered energy balance. CONCLUSIONS This study shows that EtOH site-specifically reduces POMC and PC1/3 IR in rat brain. These observations are consistent with EtOH-induced reductions of α-melanocyte-stimulating hormone (α-MSH) and POMC IR that were previously reported. As MC agonists have been shown to blunt EtOH intake in rodents, exogenous MC receptor agonists, as well as targets that may increase the synthesis of endogenous α-MSH (e.g., PC1/3), may have therapeutic value for treating alcohol abuse disorders and alcoholism.
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Affiliation(s)
- Montserrat Navarro
- Department of Psychology, University of North Carolina at Chapel Hill, CB#3270, Chapel Hill, NC, 27599-3270, USA
| | - Inmaculada Cubero
- Departamento de Neurociencia y Ciencias de la Salud, Universidad de Almería, Almería, 04120, Spain
| | - Todd E. Thiele
- Department of Psychology, University of North Carolina at Chapel Hill, CB#3270, Chapel Hill, NC, 27599-3270, USA
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16
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Helwig M, Herwig A, Heldmaier G, Barrett P, Mercer JG, Klingenspor M. Photoperiod-dependent regulation of carboxypeptidase E affects the selective processing of neuropeptides in the seasonal Siberian hamster (Phodopus sungorus). J Neuroendocrinol 2013; 25:190-7. [PMID: 22967033 DOI: 10.1111/j.1365-2826.2012.02384.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 08/10/2012] [Accepted: 09/05/2012] [Indexed: 11/30/2022]
Abstract
The production of bioactive peptides from biologically inactive precursors involves extensive post-translational processing, including enzymatic cleavage by proteolytic peptidases. Endoproteolytic prohormone-convertases initially cleave the precursors of many neuropeptides at specific amino acid sequences to generate intermediates with basic amino acid extensions on their C-termini. Subsequently, the related exopeptidases, carboxypeptidases D and E (CPD and CPE), are responsible for removing these amino acids before the peptides achieve biological activity. We investigated the effect of photoperiod on the processing of the neuropeptide precursor pro-opiomelanocortin (POMC) and its derived neuropeptides, α-melanocyte-stimulating hormone (MSH) and β-endorphin (END), within the hypothalamus of the seasonal Siberian hamster (Phodopus sungorus). We thus compared hypothalamic distribution of CPD, CPE, α-MSH and β-END using immunohistochemistry and measured the enzyme activity of CPE and concentrations of C-terminally cleaved α-MSH in short-day (SD; 8 : 16 h light/dark) and long-day (LD; 16 : 8 h light/dark) acclimatised hamsters. Increased immunoreactivity (-IR) of CPE, as well as higher CPE activity, was observed in SD. This increase was accompanied by more β-END-IR cells and substantially higher levels of C- terminally cleaved α-MSH, as determined by radioimmunoassay. Our results suggest that exoproteolytic cleavage of POMC-derived neuropeptides is tightly regulated by photoperiod in the Siberian hamster. Higher levels of biological active α-MSH- and β-END in SD are consistent with the hypothesis that post-translational processing is a key event in the regulation of seasonal energy balance.
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Affiliation(s)
- M Helwig
- Department of Anatomy & Neurobiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Tamura Y, Shintani M, Inoue H, Monden M, Shiomi H. Regulatory mechanism of body temperature in the central nervous system during the maintenance phase of hibernation in Syrian hamsters: Involvement of β-endorphin. Brain Res 2012; 1448:63-70. [DOI: 10.1016/j.brainres.2012.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 01/19/2012] [Accepted: 02/02/2012] [Indexed: 01/17/2023]
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18
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Jethwa PH, Warner A, Fowler MJ, Murphy M, de Backer MW, Adan RAH, Barrett P, Brameld JM, Ebling FJP. Short-days induce weight loss in Siberian hamsters despite overexpression of the agouti-related peptide gene. J Neuroendocrinol 2010; 22:564-75. [PMID: 20367758 DOI: 10.1111/j.1365-2826.2010.02001.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many vertebrates express profound annual cycles of body fattening, although it is not clear whether these represent differential activity of the central pathways known to mediate homeostatic control of food intake and energy expenditure, or whether the recent discovery of a major role for pars tuberalis-ependymal signalling points towards novel mechanisms. We examined this in the Siberian hamster (Phodopus sungorus) by using gene transfection to up-regulate a major orexigenic peptide, agouti-related peptide (AgRP), and then determined whether this increased anabolic drive could prevent the short-day induced winter catabolic state. Infusions of a recombinant adeno-associated virus encoding an AgRP construct into the hypothalamus of hamsters in the long-day obese phase of their seasonal cycle produced a 20% gain in body weight over 6 weeks compared to hamsters receiving a control reporter construct, reflecting a significant increase in food intake and a significant decrease in energy expenditure. However, all hamsters showed a significant, prolonged decrease in body weight when exposed to short photoperiods, despite the hamsters expressing the AgRP construct maintaining a higher food intake and lower energy expenditure relative to the control hamsters. Visualisation of the green fluorescent protein reporter and analysis of AgRP-immunoreactivity confirmed widespread expression of the construct in the hypothalamus, which was maintained for the 21-week duration of the study. In conclusion, the over-expression of AgRP in the hypothalamus produced a profoundly obese state but did not block the seasonal catabolic response, suggesting a separation of rheostatic mechanisms in seasonality from those maintaining homeostasis of energy metabolism.
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Affiliation(s)
- P H Jethwa
- School of Biomedical Sciences, University of Nottingham Medical School, Queens Medical Centre, Nottingham, UK
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19
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Rhea JM, Wegener C, Bender M. The proprotein convertase encoded by amontillado (amon) is required in Drosophila corpora cardiaca endocrine cells producing the glucose regulatory hormone AKH. PLoS Genet 2010; 6:e1000967. [PMID: 20523747 PMCID: PMC2877730 DOI: 10.1371/journal.pgen.1000967] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 04/21/2010] [Indexed: 12/01/2022] Open
Abstract
Peptide hormones are potent signaling molecules that coordinate animal physiology, behavior, and development. A key step in activation of these peptide signals is their proteolytic processing from propeptide precursors by a family of proteases, the subtilisin-like proprotein convertases (PCs). Here, we report the functional dissection of amontillado (amon), which encodes the Drosophila homolog of the mammalian PC2 protein, using cell-type specific inactivation and rescue experiments, and we show that amon is required in the islet-like adipokinetic hormone (AKH)–producing cells that regulate sugar homeostasis. In Drosophila, AKH acts analogously to vertebrate glucagon to increase circulating sugar levels from energy stores, while insulin-like peptides (DILPs) act to decrease sugar levels. amon mutant larvae have significantly reduced hemolymph sugar levels, and thus phenocopy larvae where the AKH–producing cells in the corpora cardiaca have been ablated. Reduction of amon expression in these cells via cell-specific RNA inactivation also results in larvae with reduced sugar levels while expression of amon in AKH cells in an amon mutant background rescues hypoglycemia. Hypoglycemia in larvae resulting from amon RNA inactivation in the AKH cells can be rescued by global expression of the akh gene. Finally, mass spectrometric profiling shows that the production of mature AKH is inhibited in amon mutants. Our data indicate that amon function in the AKH cells is necessary to maintain normal sugar homeostasis, that amon functions upstream of akh, and that loss of mature AKH is correlated with loss of amon activity. These observations indicate that the AKH propeptide is a proteolytic target of the amon proprotein convertase and provide evidence for a conserved role of PC2 in processing metabolic peptide hormones. Peptide hormones are important signaling molecules that coordinate physiology, behavior, and development. A key step in production of peptide hormones is the proteolytic cleavage of larger inactive precursors by prohormone convertases (PCs). Studies in a variety of organisms, including humans, have shown that deficiencies in PC genes lead to complex and detrimental changes. We used fruitfly genetics to dissect the function of Drosophila PC2, encoded by the amon gene, in the regulation of carbohydrate metabolism. We found that amon is expressed in endocrine cells of the corpora cardiaca that produce the sugar-mobilizing adipokinetic hormone (AKH), a functional analog of vertebrate glucagon. Previous studies suggest that the AKH–producing cells are homologs of the glucagon-producing islet alpha-cells in the pancreas. We found that flies with amon deficiency had significantly reduced hemolymph (insect “blood”) sugar levels. Using cell-type specific inactivation and rescue experiments, we show that amon expression in the AKH cells is necessary and sufficient for normal sugar regulation. We also demonstrate that AKH production is inhibited in amon mutants. Our results indicate that amon is necessary to maintain normal hemolymph sugar levels by activating AKH and suggest a conservation of PC2 function in processing peptide hormones between flies and mammals.
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Affiliation(s)
- Jeanne M. Rhea
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
| | - Christian Wegener
- Emmy Noether Neuropeptide Group, Department of Animal Physiology, Philipps University, Marburg, Germany
| | - Michael Bender
- Department of Genetics, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
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Bailey MT, Walton JC, Dowd SE, Weil ZM, Nelson RJ. Photoperiod modulates gut bacteria composition in male Siberian hamsters (Phodopus sungorus). Brain Behav Immun 2010; 24:577-84. [PMID: 20045457 DOI: 10.1016/j.bbi.2009.12.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2009] [Revised: 12/21/2009] [Accepted: 12/27/2009] [Indexed: 01/07/2023] Open
Abstract
Seasonal changes in day length (i.e., photoperiod) provide animals with a reliable environmental cue to determine time of year, and many physiological changes occur in laboratory animals simply by extending or shortening day length. Male Siberian hamsters (Phodopus sungorus) housed in long summer-like day lengths have significantly elevated body and fat masses compared to short-day hamsters. Because others have demonstrated that the intestinal microbiota of humans and rodents promotes host adiposity, we hypothesized that photoperiod-induced changes in body and fat masses could be associated with changes in the microbial composition in the intestines. We used bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) to assess microbial diversity in the cecal contents of hamsters; long days significantly increased the relative abundance of bacteria in the phylum Proteobacteria. This effect was primarily due to a significant increase in the abundance of the genus Citrobacter, with both the abundance of Proteobacteria and Citrobacter spp. significantly correlated with body mass and with inguinal fat mass. In general, the abundance of the Firmicutes phylum was inversely associated with body mass. These data indicate that the intestinal microbiota are responsive to changes in photoperiod and suggest that these changes may in part influence photoperiodic changes in body and fat masses.
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Affiliation(s)
- Michael T Bailey
- Section of Oral Biology, College of Dentistry, The Ohio State University, Columbus, OH 43210, USA.
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21
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López M, Tena-Sempere M, Diéguez C. Cross-talk between orexins (hypocretins) and the neuroendocrine axes (hypothalamic-pituitary axes). Front Neuroendocrinol 2010; 31:113-27. [PMID: 19654017 DOI: 10.1016/j.yfrne.2009.07.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 07/28/2009] [Accepted: 07/29/2009] [Indexed: 02/06/2023]
Abstract
Lesioning and electrical stimulation experiments carried out during the first half of the twentieth century showed that the lateral hypothalamic area (LHA) is involved in the neuroendocrine control of hormone secretion. However, the molecular basis of this phenomenon remained unclear until fifty years later when in 1998, two different laboratories discovered a new family of hypothalamic neuropeptides, the orexins or hypocretins (OX-A/Hcrt1 and OX-B/Hcrt2). Since then, remarkable evidence has revealed that orexins/hypocretins play a prominent role in regulating virtually all the neuroendocrine axes, acting as pivotal signals in the coordination of endocrine responses with regards to sleep, arousal and energy homeostasis. The clinical relevance of these actions is supported by human data showing impairment of virtually all the neuroendocrine axes in orexin/hypocretin-deficient narcoleptic patients. Here, we summarize more than ten years of knowledge about the orexins/hypocretins with particular focus on their role as neuroendocrine regulators. Understanding this aspect of orexin/hypocretin physiology could open new therapeutic possibilities in the treatment of sleep, energy homeostasis and endocrine pathologies.
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Affiliation(s)
- Miguel López
- Department of Physiology, School of Medicine, University of Santiago de Compostela - Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain.
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Lee S, Lee CE, Elias CF, Elmquist JK. Expression of the diabetes-associated gene TCF7L2 in adult mouse brain. J Comp Neurol 2010; 517:925-39. [PMID: 19845015 DOI: 10.1002/cne.22199] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Polymorphisms of the gene TCF7L2 (transcription factor 7-like 2) are strongly associated with the development and progression of type 2 diabetes. TCF7L2 is important in the development of peripheral organs such as adipocytes, pancreas, and the intestine. However, very little is known about its expression elsewhere. In this study we used in situ hybridization histochemistry to show that TCF7L2 has a unique expression pattern in the mouse brain. TCF7L2 is expressed in two distinct populations. First, it is highly expressed in thalamic and tectal structures. Additionally, TCF7L2 mRNA is expressed at moderate to low levels in specific cells of the hypothalamus, preoptic nucleus, and circumventricular organs. Collectively, these patterns of expression suggest that TCF7L2 has distinct functions within the brain, with a general role in the development and maintenance of thalamic and midbrain neurons, and then a distinct role in autonomic homeostasis.
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Affiliation(s)
- Syann Lee
- Department of Internal Medicine and Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9077, USA
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23
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Mountjoy KG. Distribution and function of melanocortin receptors within the brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 681:29-48. [PMID: 21222258 DOI: 10.1007/978-1-4419-6354-3_3] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Biological responses to pro-opiomelanocortin (POMC)-derived peptides administered in the brain were documented in the 1950s but their molecular mechanisms of action only began to be resolved with the mapping of melanocortin receptor subtypes to specific brain regions in the 1990s. Out of the five melanocortin receptor subtypes, MC3R and MC4R are widely recognised as 'neural' melanocortin receptors. In situ hybridization anatomical mapping of these receptor subtypes to distinct hypothalamic nuclei first indicated their roles in energy homeostasis, roles that were later confirmed with the obese phenotypes exhibited by Mc3R and Mc4R knockout mice. It is perhaps less well known however, that all five melanocortin receptor subtypes have been detected in developing and/or adult brains of various species. This chapter provides a comprehensive summary of the detection and mapping of each melanocortin receptor subtype in mammalian, chicken and fish brains and relates the sites of expression to functions that are either known or proposed for each receptor subtype.
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Affiliation(s)
- Kathleen G Mountjoy
- Departments of Physiology and Molecular Medicine and Pathology, School of Medical Sciences, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, 1023, New Zealand.
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Nilaweera KN, Archer ZA, Campbell G, Mayer CD, Balik A, Ross AW, Mercer JG, Ebling FJP, Morgan PJ, Barrett P. Photoperiod regulates genes encoding melanocortin 3 and serotonin receptors and secretogranins in the dorsomedial posterior arcuate of the Siberian hamster. J Neuroendocrinol 2009; 21:123-31. [PMID: 19076271 DOI: 10.1111/j.1365-2826.2008.01810.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster are currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study aimed to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified several photoperiodically regulated genes in the dmpARC that are known to have roles in secretory and intracellular signalling pathways. These include secretogranin (sg) III and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signalling pathway), all of which increase in expression under a short photoperiod. The spatial relationship between receptor signalling and potential secretory pathways was investigated by dual in situ hybridisation, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurones expressing VGF mRNA and that a sub-population (approximately 40%) of these neurones express MC3-R. These gene expression changes in dmpARC neurones may reflect the functional requirement of these neurones for seasonal physiological responses of the hamster.
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Affiliation(s)
- K N Nilaweera
- University of Aberdeen, Rowett Institute of Nutrition and Health, Bucksburn, Aberdeen, UK
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25
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Yanagita K, Shiraishi JI, Fujita M, Bungo T. Effects of N-terminal fragments of beta-endorphin on feeding in chicks. Neurosci Lett 2008; 442:140-2. [PMID: 18638524 DOI: 10.1016/j.neulet.2008.07.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 07/08/2008] [Accepted: 07/08/2008] [Indexed: 11/20/2022]
Abstract
It is known that N-terminal fragments of beta-endorphin have biological activities, such as an antagonism effect of beta-endorphin (1-31) on the secretion of hormones or thermoregulation in mammals. We studied the effects of the N-terminal fragments on feeding behavior in male broiler chicks. Intracerebroventricular administration of beta-endorphin (1-27) (0.4nmol) stimulated feeding behavior compared with saline control during the 60-min experimental period. beta-Endorphin (1-17) (2.0nmol) also increased food intake at 30min postinjection. Co-injection of either beta-endorphin (1-27) or (1-17) was effective in reducing full-length beta-endorphin-induced feeding in chicks. These data suggest that the N-terminal fragments of beta-endorphin act as a partial agonist, and may regulate the activity of the central opioidergic system in chicks.
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Affiliation(s)
- Kouichi Yanagita
- Laboratory of Animal Behavior and Physiology, Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8528, Japan
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26
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Abstract
Photoperiod exerts profound influence on the physiology of mammals through the action of melatonin on the neuroendocrine system. Over the last 20 years, studies have moved away from a melatonin receptor-focused approach to understanding how photoperiod regulates neuroendocrine activity through studies of downstream effects on gene expression. This paper reviews the recent progress made in our understanding of the effects of photoperiod on gene expression in the hypothalamus, and considers how this new information can be reconciled with the species-specific location of melatonin receptors.
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Affiliation(s)
- P J Morgan
- Rowett Institute, Bucksburn, Aberdeen, UK.
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27
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Revel FG, Saboureau M, Pévet P, Simonneaux V, Mikkelsen JD. RFamide-related peptide gene is a melatonin-driven photoperiodic gene. Endocrinology 2008; 149:902-12. [PMID: 18079200 DOI: 10.1210/en.2007-0848] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In seasonal species, various physiological processes including reproduction are organized by photoperiod via melatonin, but the mechanisms of melatonin action are still unknown. In birds, the peptide gonadotropin-inhibiting hormone (GnIH) has been shown to have inhibitory effects on reproductive activity and displays seasonal changes of expression. Here we present evidence in mammals that the gene orthologous to GnIH, the RFamide-related peptide (RFRP) gene, expressed in the mediobasal hypothalamus, is strongly regulated by the length of the photoperiod, via melatonin. The level of RFRP mRNA and the number of RFRP-immunoreactive cell bodies were reduced in sexually quiescent Syrian and Siberian hamsters acclimated to short-day photoperiod (SD) compared with sexually active animals maintained under long-day photoperiod (LD). This was contrasted in the laboratory Wistar rat, a non-photoperiodic breeder, in which no evidence for RFRP photoperiodic modulation was seen. In Syrian hamsters, the reduction of RFRP expression in SD was independent from secondary changes in gonadal steroids. By contrast, the photoperiodic variation of RFRP expression was abolished in pinealectomized hamsters, and injections of LD hamsters with melatonin for 60 d provoked inhibition of RFRP expression down to SD levels, indicating that the regulation is dependent on melatonin. Altogether, these results demonstrate that in these hamster species, the RFRP neurons are photoperiodically modulated via a melatonin-dependent process. These observations raise questions on the role of RFRP as a general inhibitor of reproduction and evoke new perspectives for understanding how melatonin controls seasonal processes via hypothalamic targets.
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Affiliation(s)
- Florent G Revel
- Département de Neurobiologie des Rythmes, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université Louis Pasteur-Institut Fédératif de Recherche des Neurosciences, Strasbourg, France
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28
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Deboer MD, Zhu X, Levasseur PR, Inui A, Hu Z, Han G, Mitch WE, Taylor JE, Halem HA, Dong JZ, Datta R, Culler MD, Marks DL. Ghrelin treatment of chronic kidney disease: improvements in lean body mass and cytokine profile. Endocrinology 2008; 149:827-35. [PMID: 18039782 PMCID: PMC2219314 DOI: 10.1210/en.2007-1046] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Chronic kidney disease (CKD) is associated with an increase in inflammatory cytokines and can result in cachexia with loss of muscle and fat stores. We previously demonstrated the efficacy of treating a model of cancer cachexia with ghrelin and a ghrelin receptor agonist. Currently, we examine a surgical model of CKD in rats, resulting in uremia and decreased accrual of lean body mass. Treatment with ghrelin and two ghrelin receptor agonists (BIM-28125 and BIM-28131) resulted in increased food intake and an improvement in lean body mass accrual that was related in part to a decrease in muscle protein degradation as assessed by muscle levels of the 14-kDa actin fragment resulting from cleaved actomyosin. Additionally, there was a decrease in circulating inflammatory cytokines in nephrectomized animals treated with ghrelin relative to saline treatment. Ghrelin-treated animals also had a decrease in the expression of IL-1 receptor in the brainstem and a decrease in expression of prohormone convertase-2, an enzyme involved in the processing of proopiomelanocortin to the anorexigenic peptide alpha-MSH. We conclude that ghrelin treatment in uremia results in improved lean mass accrual in part due to suppressed muscle proteolysis and possibly related to antiinflammatory effects.
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MESH Headings
- Absorptiometry, Photon
- Animals
- Body Weight/drug effects
- Cachexia/drug therapy
- Cachexia/etiology
- Cachexia/immunology
- Cytokines/blood
- Cytokines/genetics
- Dactinomycin/metabolism
- Disease Models, Animal
- Eating/drug effects
- Gene Expression/drug effects
- Ghrelin/pharmacology
- Growth Hormone/blood
- Inflammation/blood
- Inflammation/drug therapy
- Inflammation/etiology
- Insulin-Like Growth Factor I/metabolism
- Male
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Nephrectomy
- Neuropeptides/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Inbred F344
- Receptors, Ghrelin/agonists
- Renal Insufficiency, Chronic/complications
- Renal Insufficiency, Chronic/drug therapy
- Renal Insufficiency, Chronic/immunology
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Affiliation(s)
- Mark D Deboer
- Department of Pediatrics, University of Virginia, Charlottesville, VA 22908, USA
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29
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Abstract
This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, United States.
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30
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Herwig A, Ivanova EA, Lydon H, Barrett P, Steinlechner S, Loudon AS. Histamine H3 receptor and orexin A expression during daily torpor in the Djungarian hamster (Phodopus sungorus). J Neuroendocrinol 2007; 19:1001-7. [PMID: 18001330 DOI: 10.1111/j.1365-2826.2007.01620.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Seasonal animals use different strategies to reduce energy expenditure in the face of reduced seasonal food availability. For example, the ground squirrel enters a hibernation state with reduced metabolism, hypothermia and suppressed central nervous system activity, whereas the Djungarian hamster (Phodopus sungorus) employs daily bouts of torpor associated with reduced body temperature and energy expenditure. Studies in the hibernating ground squirrel implicate an increase in histamine synthesis and histamine H(3) receptor expression in the brain as a central mechanism governing hibernation. In the present study, we demonstrate an up-regulation of H(3) receptors in several brain nuclei in the Djungarian hamster during bouts of daily torpor, a shallow form of hypothermia, suggesting that histaminergic pathways may play a general role in maintaining low body temperature and torpor state in mammals. These regions include the arcuate nucleus, dorsomedial hypothalamus, suprachiasmatic nucleus, dorsal lateral geniculate nucleus and tuberomammillary nucleus. Interestingly, expression of the mRNA for orexins, a group of neuropeptides that increase wakefulness, remains unchanged during the arousal from daily torpor, suggesting that this classic 'arousal' pathway is not involved in the transition from a hypothermic to the euthermic state.
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Affiliation(s)
- A Herwig
- Institute of Zoology, University of Veterinary Medicine, Hannover, Germany
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31
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Nillni EA. Regulation of prohormone convertases in hypothalamic neurons: implications for prothyrotropin-releasing hormone and proopiomelanocortin. Endocrinology 2007; 148:4191-200. [PMID: 17584972 DOI: 10.1210/en.2007-0173] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent evidence demonstrated that posttranslational processing of neuropeptides is critical in the pathogenesis of obesity. Leptin or other physiological changes affects the biosynthesis and processing of many peptides hormones as well as the regulation of the family of prohormone convertases responsible for the maturation of these hormones. Regulation of energy balance by leptin involves regulation of several proneuropeptides such as proTRH and proopiomelanocortin. These proneuropeptide precursors require for their maturation proteolytic cleavage by the prohormone convertases 1 and 2 (PC1/3 and PC2). Because biosynthesis of mature peptides in response to leptin requires prohormone processing, it is hypothesized that leptin might regulate hypothalamic PC1/3 and PC2 expression, ultimately leading to coordinated processing of prohormones into mature peptides. Leptin has been shown to increase PC1/3 and PC2 promoter activities, and starvation of rats, leading to low serum leptin levels, resulted in a decrease in PC1/3 and PC2 gene and protein expression in the paraventricular and arcuate nucleus of the hypothalamus. Changes in nutritional status also changes proopiomelanocortin processing in the nucleus of the solitary tract, but this is not reversed by leptin. The PCs are also physiologically regulated by states of hyperthyroidism, hyperglycemia, inflammation, and suckling, and a recently discovered nescient helix-loop-helix-2 transcription factor is the first one to show an ability to regulate the transcription of PC1/3 and PC2. Therefore, the coupled regulation of proneuropeptide/processing enzymes may be a common process, by which cells generate more effective processing of prohormones into mature peptides.
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Affiliation(s)
- Eduardo A Nillni
- Division of Endocrinology, Department of Medicine, Brown Medical School/Rhode Island Hospital, 55 Claverick Street, Third floor, Room 320, Providence, Rhode Island 02903, USA.
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32
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Perello M, Stuart RC, Nillni EA. Differential effects of fasting and leptin on proopiomelanocortin peptides in the arcuate nucleus and in the nucleus of the solitary tract. Am J Physiol Endocrinol Metab 2007; 292:E1348-57. [PMID: 17227963 DOI: 10.1152/ajpendo.00466.2006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The alpha-melanocyte-stimulating hormone (alpha-MSH), derived from proopiomelanocortin (POMC), is generated by a posttranslational processing mechanism involving the prohormone convertases (PCs) PC1/3 and PC2. In the brain, alpha-MSH is produced in the arcuate nucleus (ARC) of the hypothalamus and in the nucleus of the solitary tract (NTS) of the medulla. This peptide is key in controlling energy balance, as judged by changes observed at transcriptional level. However, little information is available regarding the biosynthesis of the precursor POMC and the production of its processed peptides during feeding, fasting, and fasting plus leptin in the ARC compared with the NTS in conjunction with the PC activity. In this study we found that, in the ARC, pomc mRNA, POMC-derived peptides, and PC1/3 all decreased during fasting, and administration of leptin reversed these effects. In contrast, in the NTS, where there is a large amount of a 28.1-kDa peptide similar in size to POMC, the 28.1-kDa peptide and other POMC-derived peptides, including alpha-MSH, were further accumulated in fasting conditions, whereas pomc mRNA decreased. These changes were not reversed by leptin. We also observed that, during fasting, PC2 levels decreased in the NTS. These data suggest that, in the NTS, fasting induced changes in POMC biosynthesis, and processing is independent of leptin. These observations indicate that changes in energy status affect POMC in the brain in a tissue-specific manner. This represents a novel aspect in the regulation of energy balance and may have implications in the pathophysiology of obesity.
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Affiliation(s)
- Mario Perello
- Division of Endocrinology, Department of Medicine, Brown University, Rhode Island Hospital, Providence, Rhode Island 02903, USA
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33
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Król E, Tups A, Archer ZA, Ross AW, Moar KM, Bell LM, Duncan JS, Mayer C, Morgan PJ, Mercer JG, Speakman JR. Altered expression of SOCS3 in the hypothalamic arcuate nucleus during seasonal body mass changes in the field vole, Microtus agrestis. J Neuroendocrinol 2007; 19:83-94. [PMID: 17214870 DOI: 10.1111/j.1365-2826.2006.01507.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have previously shown that cold-acclimated (8 degrees C) male field voles (Microtus agrestis) transferred from short day (SD, 8 h light) to long day (LD, 16 h light) photoperiod exhibit an increase in body mass lasting 4 weeks, after which they stabilise at a new plateau approximately 7.5 g (24.8%) higher than animals maintained in SD. By infusing voles with exogenous leptin, we have also demonstrated that SD voles respond to the hormone by reducing body mass and food intake, whereas LD animals increasing body mass are resistant to leptin treatment. In the present study, we investigated whether seasonal changes in body mass could be linked to modulation of the leptin signal by suppressor of cytokine signalling-3 (SOCS3). We used in situ hybridisation to examine hypothalamic arcuate nucleus (ARC) expression of SOCS3, neuropeptide Y (NPY), agouti-related peptide (AgRP), pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) genes in 90 voles exposed to either SD or LD for up to 11 weeks. LD voles increasing body mass had significantly higher levels of SOCS3 mRNA than SD or LD voles with a stable body mass. There were no associated changes in expression of NPY, AgRP, POMC and CART genes. These results suggest that voles that regulate body mass at either the lower (SD) or upper (LD) plateau remain sensitive to leptin action, whereas SOCS3-mediated leptin resistance is a short-term mechanism that enables animals to move between the stable body mass plateaus. Our data provide evidence that expression of SOCS3 in the ARC is involved in the modulation of the strength of the leptin signal to facilitate seasonal cycles in body mass and adiposity.
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Affiliation(s)
- E Król
- Division of Obesity and Metabolic Health, Rowett Research Institute, Aberdeen Centre for Energy Regulation and Obesity (ACERO), Bucksburn, Aberdeen, UK.
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