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Morina IY, Romanova IV. Orexin-Immunopositive Structures in the Thalamic Reticular Nucleus. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022040135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Montesano A, Baumgart M, Avallone L, Castaldo L, Lucini C, Tozzini ET, Cellerino A, D'Angelo L, de Girolamo P. Age-related central regulation of orexin and NPY in the short-lived African killifish Nothobranchius furzeri. J Comp Neurol 2019; 527:1508-1526. [PMID: 30666646 DOI: 10.1002/cne.24638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 12/28/2018] [Accepted: 01/02/2019] [Indexed: 12/15/2022]
Abstract
Orexin A (OXA) and neuropeptide Y (NPY) are two hypothalamic neuropeptides involved in the regulation of feeding behavior and food intake in all vertebrates. Accumulating evidences document that they undergo age-related modifications, with consequences on metabolism, sleep/wake disorders and progression of neurodegenerations. The present study addressed the age related changes in expression and distribution of orexin A (its precursor is also known as hypocretin-HCRT) and NPY, and their regulation by food intake in the short-lived vertebrate model Nothobranchius furzeri. Our experiments, conducted on male specimens, show that: (a) HCRT and OXA and NPY mRNA and protein are localized in neurons of diencephalon and optic tectum, as well as in numerous fibers projecting through the entire neuroaxis, and are colocalized in specific nuclei; (b) in course of aging, HCRT and NPY expressing neurons are localized also in telencephalon and rhombencephalon; (c) HCRT expressing neurons increased slightly in the diencephalic area of old animals and in fasted animals, whereas NPY increased sharply; (d) central HCRT levels are not regulated neither in course of aging nor by food intake; and (e) central NPY levels are augmented in course of aging, and regulated by food intake only in young. These findings represent a great novelty in the study of central orexinergic and NPY-ergic systems in vertebrates', demonstrating an uncommon and unprecedented described regulation of these two orexigenic neuropeptides.
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Affiliation(s)
- Alessia Montesano
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy.,Leibniz-Institute on Aging - Fritz Lipmann Institute (FLI), Lab. Biology of Aging, Jena, Germany
| | - Mario Baumgart
- Leibniz-Institute on Aging - Fritz Lipmann Institute (FLI), Lab. Biology of Aging, Jena, Germany
| | - Luigi Avallone
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Luciana Castaldo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | - Carla Lucini
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
| | | | - Alessandro Cellerino
- Leibniz-Institute on Aging - Fritz Lipmann Institute (FLI), Lab. Biology of Aging, Jena, Germany.,Scuola Normale Superiore, Bio@SNS, c/o Istituto di Biofisica del CNR, Pisa, Italy
| | - Livia D'Angelo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy.,Stazione Zoologica Anton Dohrn, Biology and Evolution of Marine Organisms, Naples, Italy
| | - Paolo de Girolamo
- Department of Veterinary Medicine and Animal Productions, University of Naples Federico II, Naples, Italy
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Volkoff H. The Neuroendocrine Regulation of Food Intake in Fish: A Review of Current Knowledge. Front Neurosci 2016; 10:540. [PMID: 27965528 PMCID: PMC5126056 DOI: 10.3389/fnins.2016.00540] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/07/2016] [Indexed: 12/14/2022] Open
Abstract
Fish are the most diversified group of vertebrates and, although progress has been made in the past years, only relatively few fish species have been examined to date, with regards to the endocrine regulation of feeding in fish. In fish, as in mammals, feeding behavior is ultimately regulated by central effectors within feeding centers of the brain, which receive and process information from endocrine signals from both brain and peripheral tissues. Although basic endocrine mechanisms regulating feeding appear to be conserved among vertebrates, major physiological differences between fish and mammals and the diversity of fish, in particular in regard to feeding habits, digestive tract anatomy and physiology, suggest the existence of fish- and species-specific regulating mechanisms. This review provides an overview of hormones known to regulate food intake in fish, emphasizing on major hormones and the main fish groups studied to date.
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Affiliation(s)
- Helene Volkoff
- Departments of Biology and Biochemistry, Memorial University of NewfoundlandSt. John's, NL, Canada
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The Ontogeny and Brain Distribution Dynamics of the Appetite Regulators NPY, CART and pOX in Larval Atlantic Cod (Gadus morhua L.). PLoS One 2016; 11:e0153743. [PMID: 27100086 PMCID: PMC4839749 DOI: 10.1371/journal.pone.0153743] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 04/04/2016] [Indexed: 11/19/2022] Open
Abstract
Similar to many marine teleost species, Atlantic cod undergo remarkable physiological changes during the early life stages with concurrent and profound changes in feeding biology and ecology. In contrast to the digestive system, very little is known about the ontogeny and the localization of the centers that control appetite and feed ingestion in the developing brain of fish. We examined the expression patterns of three appetite regulating factors (orexigenic: neuropeptide Y, NPY; prepro-orexin, pOX and anorexigenic: cocaine- and amphetamine-regulated transcript, CART) in discrete brain regions of developing Atlantic cod using chromogenic and double fluorescent in situ hybridization. Differential temporal and spatial expression patterns for each appetite regulator were found from first feeding (4 days post hatch; dph) to juvenile stage (76 dph). Neurons expressing NPY mRNA were detected in the telencephalon (highest expression), diencephalon, and optic tectum from 4 dph onward. CART mRNA expression had a wider distribution along the anterior-posterior brain axis, including both telencephalon and diencephalon from 4 dph. From 46 dph, CART transcripts were also detected in the olfactory bulb, region of the nucleus of medial longitudinal fascicle, optic tectum and midbrain tegmentum. At 4 and 20 dph, pOX mRNA expression was exclusively found in the preoptic region, but extended to the hypothalamus at 46 and 76 dph. Co-expression of both CART and pOX genes were also observed in several hypothalamic neurons throughout larval development. Our results show that both orexigenic and anorexigenic factors are present in the telencephalon, diencephalon and mesencephalon in cod larvae. The telencephalon mostly contains key factors of hunger control (NPY), while the diencephalon, and particularly the hypothalamus may have a more complex role in modulating the multifunctional control of appetite in this species. As the larvae develop, the overall progression in temporal and spatial complexity of NPY, CART and pOX mRNAs expression might be correlated to the maturation of appetite control regulation. These observations suggest that teleost larvae continue to develop the regulatory networks underlying appetite control after onset of exogenous feeding.
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Varricchio E, Russo F, Coccia E, Turchini GM, Francis DS, Paolucci M. The orexinergic system in rainbow trout Oncorhynchus mykiss and its regulation by dietary lipids. Microsc Res Tech 2015; 78:707-14. [PMID: 26096763 DOI: 10.1002/jemt.22528] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 04/24/2015] [Accepted: 05/10/2015] [Indexed: 12/14/2022]
Abstract
In this study, we report the distribution of orexin A (OXA), orexin B (OXB), and orexin receptor (OX2R) immunoreactive (ir) cells in the hypothalamus and gastrointestinal tract of Oncorhynchus mykiss fed diets with different dietary fatty acid compositions. Trout were fed five iso-energetic experimental diets containing fish oil, or one of four different vegetable oils (olive, sunflower, linseed, and palm oils) as the added dietary lipid source for 12 weeks. OXA, OXB, and OX2R immunoreactive neurons and nervous fibers were identified in the lateral and ventro-medial hypothalamus. OXA, OXB, and OX2R ir cells were found in the mucosa and glands of the stomach and in the mucosa of both the pyloric cecae and intestine. OX2R ir cells were localized in the mucosa layer of both the pyloric cecae and intestine. These immunohistochemical (IHC) results were confirmed via Western blotting. Antibodies against preproorexin (PPO) crossreacted with a band of ∼16 kDa in the hypothalamus, stomach, pyloric cecae, and intestine. Antibodies against OX2R crossreacted with a band of ∼38 kDa in the hypothalamus, pyloric cecae, and intestine. The presence and distribution of OXA, OXB, and OX2R ir cells in the hypothalamus and gastrointestinal tract did not appear to be affected by dietary oils. The presence of orexin system immunoreactive cells in the stomach, pyloric cecae, and intestine of rainbow trout, but not in the enteric nervous system, could suggest a possible role of these peptides as signaling of gastric emptying or endocrine modulation, implying a main local action played by orexins.
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Affiliation(s)
- Ettore Varricchio
- Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy
| | - Finizia Russo
- Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy
| | - Elena Coccia
- Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy
| | - Giovanni Mario Turchini
- School of Life and Environmental Sciences, Deakin University, Warrnambool, Victoria, Australia
| | - David Scott Francis
- School of Life and Environmental Sciences, Deakin University, Warrnambool, Victoria, Australia
| | - Marina Paolucci
- Department of Science and Technologies, University of Sannio, Benevento, 82100, Italy.,Institute of Nutrition (ISA), Avellino, 83100, Italy
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Volkoff H. Cloning and tissue distribution of appetite-regulating peptides in pirapitinga (Piaractus brachypomus
). J Anim Physiol Anim Nutr (Berl) 2015; 99:987-1001. [DOI: 10.1111/jpn.12318] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 02/25/2015] [Indexed: 12/16/2022]
Affiliation(s)
- H. Volkoff
- Departments of Biology and Biochemistry; Memorial University of Newfoundland; St. John's NL Canada
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Tuziak SM, Rise ML, Volkoff H. An investigation of appetite-related peptide transcript expression in Atlantic cod (Gadus morhua) brain following a Camelina sativa meal-supplemented feeding trial. Gene 2014; 550:253-63. [PMID: 25151310 DOI: 10.1016/j.gene.2014.08.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/09/2014] [Accepted: 08/20/2014] [Indexed: 12/17/2022]
Abstract
Camelina sativa is a hardy oilseed crop with seeds that contain high levels of ω3 polyunsaturated fatty acids and protein, which are critical components of fish feed. Camelina might thus be used as a cheaper and more sustainable supplement to fish-based products in aquaculture. Atlantic cod, Gadus morhua, is a species of interest in the aquaculture industry due to a decrease in wild populations and subsequent collapse of some cod fisheries. As cod are carnivorous fish, it is necessary to determine how this species physiologically tolerates plant-based diets. In this study, juvenile Atlantic cod were subjected to 13 weeks of either 15 or 30% camelina meal (CM)-supplemented diets or a control fish meal feed. Growth and food intake were evaluated and the mRNA expression of appetite-related hormones [pro-melanin-concentrating hormone (pmch), hypocretin (synonym: orexin, hcrt), neuropeptide Y (npy) and cocaine- and amphetamine-regulated transcript (cart)] was assessed using quantitative real-time PCR in brain regions related to food intake regulation (telencephalon/preoptic area, optic tectum/thalamus and hypothalamus). CM inclusion diets caused decreases in both growth and food intake in Atlantic cod. Optic tectum pmch transcript expression was significantly higher in fish fed the 30% CM diet compared to fish fed the 15% CM diet. In the hypothalamus, compared to fish fed the control diet, hcrt expression was significantly higher in fish fed the 30% CM diet, while npy transcript expression was significantly higher in fish fed the 15% CM diet. cart mRNA expression was not affected by diet in any brain region. Further studies are needed to determine which factors (e.g. anti-nutritional factors, palatability and nutritional deficits) contribute to reduced feed intake and growth, as well as the maximum CM inclusion level that does not negatively influence feed intake, growth rate and the transcript expression of appetite-related factors in Atlantic cod.
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Affiliation(s)
- Sarah M Tuziak
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B-3X9, Canada.
| | - Matthew L Rise
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B-3X9, Canada
| | - Hélène Volkoff
- Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B-3X9, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B-3X9, Canada
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Gatta C, Russo F, Russolillo MG, Varricchio E, Paolucci M, Castaldo L, Lucini C, de Girolamo P, Cozzi B, Maruccio L. The orexin system in the enteric nervous system of the bottlenose dolphin (Tursiops truncatus). PLoS One 2014; 9:e105009. [PMID: 25144456 PMCID: PMC4140726 DOI: 10.1371/journal.pone.0105009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/17/2014] [Indexed: 11/19/2022] Open
Abstract
This study provides a general approach to the presence and possible role of orexins and their receptors in the gut (three gastric chambers and intestine) of confined environment bottlenose dolphin. The expression of prepro-orexin, orexin A and B and orexin 1 and 2 receptors were investigated by single immunostaining and western blot analysis. The co-localization of vasoactive intestinal peptide and orexin 1 receptor in the enteric nervous system was examined by double immunostaining. Also, orexin A concentration were measured in plasma samples to assess the possible diurnal variation of the plasma level of peptide in this species. Our results showed that the orexin system is widely distributed in bottlenose dolphin enteric nervous system of the all gastrointestinal tract examined. They are very peculiar and partially differs from that of terrestrial mammals. Orexin peptides and prepro-orexin were expressed in the main stomach, pyloric stomach and proximal intestine; while orexin receptors were expressed in the all examined tracts, with the exception of main stomach where found no evidence of orexin 2 receptor. Co-localization of vasoactive intestinal peptide and orexin 1 receptor were more evident in the pyloric stomach and proximal intestine. These data could suggest a possible role of orexin system on the contractility of bottlenose dolphin gastrointestinal districts. Finally, in agreement with several reports, bottlenose dolphin orexin A plasma level was higher in the morning during fasting. Our results emphasize some common features between bottlenose dolphin and terrestrial mammals. Certainly, further functional investigations may help to better explain the role of the orexin system in the energy balance of bottlenose dolphin and the complex interaction between feeding and digestive physiology.
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Affiliation(s)
- Claudia Gatta
- Department of Veterinary Medicine and Animal Productions, University of Napoli “Federico II”, Napoli (NA), Italy
| | - Finizia Russo
- Department of Sciences and Technologies, University of Sannio, Benevento (BN), Italy
- * E-mail:
| | | | - Ettore Varricchio
- Department of Sciences and Technologies, University of Sannio, Benevento (BN), Italy
| | - Marina Paolucci
- Department of Sciences and Technologies, University of Sannio, Benevento (BN), Italy
| | - Luciana Castaldo
- Department of Veterinary Medicine and Animal Productions, University of Napoli “Federico II”, Napoli (NA), Italy
| | - Carla Lucini
- Department of Veterinary Medicine and Animal Productions, University of Napoli “Federico II”, Napoli (NA), Italy
| | - Paolo de Girolamo
- Department of Veterinary Medicine and Animal Productions, University of Napoli “Federico II”, Napoli (NA), Italy
| | - Bruno Cozzi
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro (PD), Italy
| | - Lucianna Maruccio
- Department of Veterinary Medicine and Animal Productions, University of Napoli “Federico II”, Napoli (NA), Italy
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Volkoff H. Appetite regulating peptides in red-bellied piranha, Pygocentrus nattereri: cloning, tissue distribution and effect of fasting on mRNA expression levels. Peptides 2014; 56:116-24. [PMID: 24721336 DOI: 10.1016/j.peptides.2014.03.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 03/30/2014] [Accepted: 03/31/2014] [Indexed: 11/24/2022]
Abstract
cDNAs encoding the appetite regulating peptides apelin, cocaine and amphetamine regulated transcript (CART), cholecystokinin (CCK), peptide YY (PYY) and orexin were isolated in red-bellied piranha and their mRNA tissue and brain distributions examined. When compared to other fish, the sequences obtained for all peptides were most similar to that of other Characiforme fish, as well as to Cypriniformes. All peptides were widely expressed within the brain and in several peripheral tissues, including gastrointestinal tract. In order to assess the role of these peptides in the regulation of feeding of red-bellied piranha, we compared the brain mRNA expression levels of these peptides, as well as the gut mRNA expression of CCK and PYY, between fed and 7-day fasted fish. Within the brain, fasting induced a significant increase in both apelin and orexin mRNA expressions and a decrease in CART mRNA expression, but there where were no significant differences for either PYY or CCK brain mRNA expressions between fed and fasted fish. Within the intestine, PYY mRNA expression was lower in fasted fish compared to fed fish but there was no significant difference for CCK intestine mRNA expression between fed and fasted fish. Our results suggest that these peptides, perhaps with the exception of CCK, play a major role in the regulation of feeding of red-bellied piranha.
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Affiliation(s)
- Hélène Volkoff
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
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Wall A, Volkoff H. Effects of fasting and feeding on the brain mRNA expressions of orexin, tyrosine hydroxylase (TH), PYY and CCK in the Mexican blind cavefish (Astyanax fasciatus mexicanus). Gen Comp Endocrinol 2013; 183:44-52. [PMID: 23305930 DOI: 10.1016/j.ygcen.2012.12.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 10/21/2012] [Accepted: 12/21/2012] [Indexed: 01/16/2023]
Abstract
The effects of fasting and feeding on the brain expression of orexin (OX), tyrosine hydroxylase (TH), peptide Y (PY) and cholecystokinin (CCK) were examined in the blind cavefish Astyanax fasciatus mexicanus. A 10-days fasting period induced increases in both OX and TH brain mRNA expression but had no effect on PYY and CCK expression. Periprandial changes in expression were seen for OX, TH and PYY but not for CCK. OX brain expression peaked 1h prior to a scheduled meal and decreased 1h post feeding in fed fish. A peak in TH expression was seen 1h post feeding in unfed fish whereas a peak in PYY expression was seen 1h post feeding in fed fish. Our result indicates that brain OX, TH and PYY might be involved in the central regulation of feeding of blind cavefish.
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Affiliation(s)
- Alicia Wall
- Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada
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12
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13
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Yan A, Zhang L, Tang Z, Zhang Y, Qin C, Li B, Li W, Lin H. Orange-spotted grouper (Epinephelus coioides) orexin: molecular cloning, tissue expression, ontogeny, daily rhythm and regulation of NPY gene expression. Peptides 2011; 32:1363-70. [PMID: 21600944 DOI: 10.1016/j.peptides.2011.05.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Revised: 05/04/2011] [Accepted: 05/04/2011] [Indexed: 01/27/2023]
Abstract
Orexin-A and -B, collectively called orexins, are hypothalamic neuropeptides involved in the regulation of food intake, sleep and energy balance. In this study, the full-length cDNA of prepro-orexin was isolated from the hypothalamus of orange-spotted grouper (Epinephelus coioides) using RT-PCR and RACE. The grouper prepro-orexin cDNA is 711 bp in length and encodes a 149-amino acid precursor protein that contains a 46-amino acid signal peptide, a 43-amino acid mature orexin-A peptide, a 27-amino acid mature orexin-B peptide and a 33-amino acid C terminus of unknown function. The tissue distribution and ontogeny of prepro-orexin were examined by quantitative real-time PCR. We found that the prepro-orexin mRNA is widely expressed in brain and peripheral tissues, with abundant expression in the hypothalamus. During the embryonic development, prepro-orexin mRNA was first detected in neurula stage embryos, and its expression gradually increased during the remainder of embryogenesis. Our analysis of grouper hypothalamic prepro-orexin expression showed that prepro-orexin mRNA levels were greater in the light phase than in the dark phase and increased significantly at meal-time. Intraperitoneal injection of orexin-A caused a dose-related increase in hypothalamus NPY mRNA expression level after 4h. Orexin-A also increased NPY mRNA expression level from static hypothalamic fragments incubation. Our results imply that orexin may be involved in feeding in the orange-spotted grouper and orexin-A is a stimulator of NPY mRNA expression in vivo and in vitro.
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Affiliation(s)
- Aifen Yan
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals, and the Guangdong Province Key Laboratory for Aquatic Economic Animals, Sun Yat-sen University, Guangzhou 510275, China
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Yokobori E, Kojima K, Azuma M, Kang KS, Maejima S, Uchiyama M, Matsuda K. Stimulatory effect of intracerebroventricular administration of orexin A on food intake in the zebrafish, Danio rerio. Peptides 2011; 32:1357-62. [PMID: 21616109 DOI: 10.1016/j.peptides.2011.05.010] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/08/2011] [Accepted: 05/09/2011] [Indexed: 01/21/2023]
Abstract
Orexin is a potent orexigenic neuropeptide implicated in feeding regulation of mammals. However, except for the case of goldfish, the involvement of orexin in the feeding behavior of teleost fish has not well been studied. Therefore, we investigated the role of orexin on food intake using a zebrafish (Danio rerio) model. We examined the effect of feeding status on orexin-like immunoreactivity and the expression level of orexin transcript in the brain. The number of neuronal cells showing orexin-like immunoreactivity in the hypothalamic region, including the posterior tuberal nucleus, was significantly increased in fish fasted for 7days. Orexin precursor mRNA levels in the brain obtained from fish fasted for 7 days were higher than those in fish that had been fed normally. We then investigated the effect of intracerebroventricular (ICV) administration of orexin A on food intake. Cumulative food intake was significantly increased by ICV administration of orexin A (at 0.3 and 3 pmol/g body weight, BW) during a 60-min observation period after treatment. The orexin A-induced orexigenic action (at 0.3 pmol/g BW) was blocked by treatment with an orexin receptor antagonist, SB334867, at 10 pmol/g BW. These results indicate that orexin A acts as feeding regulator in the zebrafish.
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Affiliation(s)
- Eri Yokobori
- Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama, Toyama 930-8555, Japan
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15
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Abbott M, Volkoff H. Thyrotropin Releasing Hormone (TRH) in goldfish (Carassius auratus): role in the regulation of feeding and locomotor behaviors and interactions with the orexin system and cocaine- and amphetamine regulated transcript (CART). Horm Behav 2011; 59:236-45. [PMID: 21192941 DOI: 10.1016/j.yhbeh.2010.12.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 11/24/2010] [Accepted: 12/19/2010] [Indexed: 01/15/2023]
Abstract
TRH is a peptide produced by the hypothalamus which major function in mammals is the regulation of TSH secretion by the pituitary. In fish, TRH does not appear to affect TSH secretion, suggesting that it might regulate other functions. In this study, we assessed the effects of central (intracerebroventricular, icv) injections of TRH on feeding and locomotor behavior in goldfish. TRH at 10 and 100 ng/g, but not 1 ng/g, significantly increased feeding and locomotor behaviors, as indicated by an increase in food intake and in the number of total feeding acts as compared to saline-injected fish. In order to assess possible interactions between TRH and other appetite regulators, we examined the effects of icv injections of TRH on the hypothalamic expression of orexin, orexin receptor and CART. The mRNA expression levels of all three peptides were significantly increased in fish injected with TRH at 100 ng/g as compared to saline-injected fish. Fasting increased TRH, orexin, and orexin receptor hypothalamic mRNA levels and decreased CART hypothalamic mRNA levels. Our results suggest that TRH is involved in the regulation of feeding/locomotor activity in goldfish and that this action is associated with a stimulation of both the orexin and CART systems.
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Affiliation(s)
- Meagan Abbott
- Department of Biology, Memorial University of Newfoundland, St John's, NL A1B3X9 Canada
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