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Abstract
Anorexia is a loss of appetite or an inability to eat and is often associated with eating disorders. However, animal anorexia is physiologically regulated as a part of the life cycle; for instance, during hibernation, migration or incubation. Anorexia nervosa (AN), on the other hand, is a common eating disorder among adolescent females that experience an intense fear of gaining weight due to body image distortion that results in voluntary avoidance of food intake and, thus, severe weight loss. It has been shown that the neurobiology of feeding extends beyond the hypothalamus. The prefrontal cortex (PFC) is involved in food choice and body image perception, both relevant in AN. However, little is known about the neurobiology of AN, and the lack of effective treatments justifies the use of animal models. Glial cells, the dominant population of nerve cells in the central nervous system, are key in maintaining brain homeostasis. Accordingly, recent studies suggest that glial function may be compromised by anorexia. In this review, we summarize recent findings about anorexia and glial cells.
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Association of fasting Orexin-A levels with energy intake at breakfast and subsequent snack in Chilean adolescents. Psychoneuroendocrinology 2022; 140:105718. [PMID: 35286991 DOI: 10.1016/j.psyneuen.2022.105718] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 01/21/2022] [Accepted: 03/07/2022] [Indexed: 11/23/2022]
Abstract
Orexin-A, a hormone secreted by orexin neurons, is involved in caloric-intake regulation. Current understanding is based primarily on animal studies. Studies of orexin in humans are scarce, and to our knowledge there are no prior studies in adolescents. We studied fasting Orexin-A levels related to energy intake at breakfast and a subsequent snack in adolescents (n = 668) from a longitudinal study in Chile. Body-Mass Index (BMI), components of the metabolic syndrome and fasting blood levels of leptin, insulin, ghrelin, and orexin-A were measured. Energy intake was calculated based on food weights before and after the standardized breakfast and subsequent snack. High energy intake was defined as ≥ 75th percentile. We assessed the relationship between orexin-A and high energy intake, adjusting for confounders. Higher orexin levels were associated with high breakfast energy intake (OR: 1.21; 95%CI: 0.98-1.49). Conversely, those with higher orexin levels showed a non-significant trend for lower odds of high energy intake for the snack (OR: 0.87; 95%CI: 0.70-1.07). There was a significant interaction between high breakfast energy intake and orexin levels. Those who ate more calories at breakfast displayed a lower inhibitory effect of orexin on eating at the snack (p < 0.05). There was no significant interaction between weight status and orexin. In conclusion, orexin-A levels were associated with breakfast energy intake and inversely related with subsequent snack energy intake in participants whose caloric intake at breakfast was within the normal range. Based on these findings, it appears that the association of orexin-A with energy intake depends on eating behavior.
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Chávez J, Alcántara-Alonso V, García-Luna C, Soberanes-Chávez P, Grammatopoulos D, de Gortari P. Hypothalamic TRH mediates anorectic effects of serotonin in rats. eNeuro 2022; 9:ENEURO.0077-22.2022. [PMID: 35545425 PMCID: PMC9159524 DOI: 10.1523/eneuro.0077-22.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/26/2022] [Accepted: 04/28/2022] [Indexed: 11/21/2022] Open
Abstract
Among the modulatory functions of thyrotropin-releasing hormone (TRH), an anorectic behavior in rodents is observed when centrally injected. Hypothalamic PVN neurons receive serotonergic inputs from dorsal raphe nucleus and express serotonin (5HT) receptors such as 5HT1A, 5HT2A/2C, 5HT6, which are involved in 5HT-induced feeding regulation. Rats subjected to dehydration-induced anorexia (DIA) model show increased PVN TRH mRNA expression, associated with their decreased food intake. We analyzed whether 5HT input is implicated in the enhanced PVN TRH transcription that anorectic rats exhibit, given that 5HT increases TRH expression and release when studied in vitro By using mHypoA-2/30 hypothalamic cell cultures, we found that 5HT stimulated TRH mRNA, pCREB and pERK1/2 levels. By inhibiting basal PKA or PKC activities or those induced by 5HT, pCREB or pERK1/2 content did not increase suggesting involvement of both kinases in their phosphorylation. 5HT effect on TRH mRNA was not affected by PKA inhibition, but it diminished in the presence of PKCi suggesting involvement of PKC in 5HT-induced TRH increased transcription. This likely involves 5HT2A/2C and the activation of alternative transduction pathways than those studied here. In agreement with the in vitro data, we found that injecting 5HT2A/2C antagonists into the PVN of DIA rats reversed the increased TRH expression of anorectic animals, as well as their decreased food intake; also, the agonist reduced food intake of hungry restricted animals along with elevated PVN TRH mRNA levels. Our results support that the anorectic effects of serotonin are mediated by PVN TRH in this model.Significance statementInteraction between brain peptides and neurotransmitters' pathways regulates feeding behavior, but when altered it could lead to the development of eating disorders, such as anorexia. An abnormal increased TRH expression in hypothalamic PVN results in dehydration-induced anorectic rats, associated to their low food intake. The role of neurotransmitters in that alteration is unknown, and since serotonin inhibits feeding and has receptors in PVN, we analyzed its participation in increasing TRH expression and reducing feeding in anorectic rats. By antagonizing PVN serotonin receptors in anorectic rats, we identify decreased TRH expression and increased feeding, suggesting that the anorectic effects of serotonin are mediated by PVN TRH. Elucidating brain networks involved in feeding regulation would help to design therapies for eating disorders.
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Affiliation(s)
- Jorge Chávez
- Molecular Neurophysiology laboratory, Department of Neuroscience, National Institute of Psychiatry "Ramón de la Fuente Muñiz", Mexico City, Mexico 14370
| | - Viridiana Alcántara-Alonso
- Molecular Neurophysiology laboratory, Department of Neuroscience, National Institute of Psychiatry "Ramón de la Fuente Muñiz", Mexico City, Mexico 14370
- Translational Medicine, Warwick Medical School, Coventry, United Kingdom CV4 7HL
| | - Cinthia García-Luna
- Molecular Neurophysiology laboratory, Department of Neuroscience, National Institute of Psychiatry "Ramón de la Fuente Muñiz", Mexico City, Mexico 14370
| | - Paulina Soberanes-Chávez
- Molecular Neurophysiology laboratory, Department of Neuroscience, National Institute of Psychiatry "Ramón de la Fuente Muñiz", Mexico City, Mexico 14370
| | - Dimitris Grammatopoulos
- Translational Medicine, Warwick Medical School, Coventry, United Kingdom CV4 7HL
- Institute of Precision Diagnostics and Translational Medicine, Division of Pathology, UHCW NHS Trust, Coventry, United Kingdom CV2 2DX
| | - Patricia de Gortari
- Molecular Neurophysiology laboratory, Department of Neuroscience, National Institute of Psychiatry "Ramón de la Fuente Muñiz", Mexico City, Mexico 14370.
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Lanuza F, Reyes M, Blanco E, Burrows R, Peirano P, Algarín C, Meroño T, Gahagan S. Association of fasting orexin-A levels with energy intake at breakfast and subsequent snack in Chilean adolescents. Psychoneuroendocrinology 2022; 138:105679. [PMID: 35182924 DOI: 10.1016/j.psyneuen.2022.105679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/26/2022]
Abstract
Orexin-A, a hormone secreted by orexin neurons, is involved in caloric-intake regulation. Current understanding is based primarily on animal studies. Studies of orexin in humans are scarce, and to our knowledge there are no prior studies in adolescents. We studied fasting Orexin-A levels related to energy intake at breakfast and a subsequent snack in adolescents (n = 668) from a longitudinal study in Chile. Body-Mass Index (BMI), components of the metabolic syndrome and fasting blood levels of leptin, insulin, ghrelin, and orexin-A were measured. Energy intake was calculated based on food weights before and after the standardized breakfast and subsequent snack. High energy intake was defined as ≥ 75th percentile. We assessed the relationship between orexin-A and high energy intake, adjusting for confounders. Higher orexin levels were associated with high breakfast energy intake (OR: 1.21; 95%CI: 0.98-1.49). Conversely, those with higher orexin levels showed a non-significant trend for lower odds of high energy intake for the snack (OR: 0.87; 95%CI: 0.70-1.07). There was a significant interaction between high breakfast energy intake and orexin levels. Those who ate more calories at breakfast displayed a lower inhibitory effect of orexin on eating at the snack (p < 0.05). There was no significant interaction between weight status and orexin. In conclusion, orexin-A levels were associated with breakfast energy intake and inversely related with subsequent snack energy intake in participants whose caloric intake at breakfast was within the normal range. Based on these findings, it appears that the association of orexin-A with energy intake depends on eating behavior.
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Affiliation(s)
- Fabian Lanuza
- Biomarkers and Nutrimetabolomics Laboratory, Department of Nutrition, Food Sciences and Gastronomy, Food Technology Reference Net (XIA), Nutrition and Food Safety Research Institute (INSA), Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028 Barcelona, Spain; Centro de Epidemiología Cardiovascular y Nutricional (EPICYN), Facultad de Medicina, Universidad de La Frontera, 4781218 Temuco, Chile
| | - Marcela Reyes
- Department of Public Health Nutrition, Institute of Nutrition and Food Technology (INTA), University of Chile, 7830489 Santiago, Chile
| | - Estela Blanco
- Child Development and Community Health Division, University of California San Diego, 92093-0927 La Jolla, CA, USA; Department of Public Health, Faculty of Medicine, Pontificia Universidad Católica, Santiago, Chile
| | - Raquel Burrows
- Department of Public Health Nutrition, Institute of Nutrition and Food Technology (INTA), University of Chile, 7830489 Santiago, Chile
| | - Patricio Peirano
- Department of Human Nutrition, Institute of Nutrition and Food Technology (INTA), University of Chile, 7830489 Santiago, Chile
| | - Cecilia Algarín
- Department of Human Nutrition, Institute of Nutrition and Food Technology (INTA), University of Chile, 7830489 Santiago, Chile
| | - Tomás Meroño
- Biomarkers and Nutrimetabolomics Laboratory, Department of Nutrition, Food Sciences and Gastronomy, Food Technology Reference Net (XIA), Nutrition and Food Safety Research Institute (INSA), Faculty of Pharmacy and Food Sciences, University of Barcelona, 08028 Barcelona, Spain
| | - Sheila Gahagan
- Child Development and Community Health Division, University of California San Diego, 92093-0927 La Jolla, CA, USA.
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Muthmainah M, Gogos A, Sumithran P, Brown RM. Orexins (hypocretins): The intersection between homeostatic and hedonic feeding. J Neurochem 2021; 157:1473-1494. [PMID: 33608877 DOI: 10.1111/jnc.15328] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/11/2021] [Accepted: 02/15/2021] [Indexed: 12/11/2022]
Abstract
Orexins are hypothalamic neuropeptides originally discovered to play a role in the regulation of feeding behaviour. The broad connections of orexin neurons to mesocorticolimbic circuitry suggest they may play a role in mediating reward-related behaviour beyond homeostatic feeding. Here, we review the role of orexin in a variety of eating-related behaviour, with a focus on reward and motivation, and the neural circuits driving these effects. One emerging finding is the involvement of orexins in hedonic and appetitive behaviour towards palatable food, in addition to their role in homeostatic feeding. This review discusses the brain circuitry and possible mechanisms underlying the role of orexins in these behaviours. Overall, there is a marked bias in the literature towards studies involving male subjects. As such, future work needs to be done to involve female subjects. In summary, orexins play an important role in driving motivation for high salient rewards such as highly palatable food and may serve as the intersection between homeostatic and hedonic feeding.
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Affiliation(s)
- Muthmainah Muthmainah
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia.,Department of Anatomy, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Andrea Gogos
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia
| | - Priya Sumithran
- Department of Medicine (Austin), University of Melbourne, Heidelberg, Vic., Australia.,Department of Endocrinology, Austin Health, Heidelberg, Vic., Australia
| | - Robyn M Brown
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia
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6
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Mixed sorghum and quinoa flour improves protein quality and increases antioxidant capacity in vivo. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2020.109597] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Reyes-Ortega P, Ragu Varman D, Rodríguez VM, Reyes-Haro D. Anorexia induces a microglial associated pro-inflammatory environment and correlates with neurodegeneration in the prefrontal cortex of young female rats. Behav Brain Res 2020; 392:112606. [PMID: 32387351 DOI: 10.1016/j.bbr.2020.112606] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 02/12/2020] [Accepted: 02/27/2020] [Indexed: 01/13/2023]
Abstract
Dehydration-Induced Anorexia (DIA) is a murine model that reproduces weight loss and avoidance of food, despite its availability. The prefrontal cortex (PFC) integrates sensory inputs and updates associative learning to promote (hunger) or inhibit (satiety) food-seeking behavior. In this study we tested if anorexia induces a pro-inflammatory environment associated with microglia in the medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC), specific subregions of the PFC involved in appetite. Our results showed that anorexia increased microglial density, promoted a de-ramified morphology and augmented the de-ramified/ramified ratio in the mPFC and OFC but not in the motor cortex. Anorexia also increased the expression of the pro-inflammatory cytokines TNF-α, IL-6 and IL-1β. This pro-inflammatory environment associated with microglia activation correlates with neuronal damage as revealed by Fluoro Jade C (FJC) and NeuN immunolabeling. We conclude that anorexia triggers a pro-inflammatory environment associated with microglia that correlates with neurodegeneration in the mPFC and OFC.
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Affiliation(s)
- Pamela Reyes-Ortega
- Departamento de Neurobiología Celular y Molecular. Instituto de Neurobiología. Universidad Nacional Autónoma de México, Campus Juriquilla. Boulevard Juriquilla #3001. Juriquilla, Querétaro; CP 76230, México
| | - Durairaj Ragu Varman
- Departamento de Neurobiología Celular y Molecular. Instituto de Neurobiología. Universidad Nacional Autónoma de México, Campus Juriquilla. Boulevard Juriquilla #3001. Juriquilla, Querétaro; CP 76230, México; Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Verónica M Rodríguez
- Departamento de Neurobiología Conductual y Cognitiva. Instituto de Neurobiología. Universidad Nacional Autónoma de México, Campus Juriquilla. Boulevard Juriquilla #3001. Juriquilla, Querétaro; CP 76230, México
| | - Daniel Reyes-Haro
- Departamento de Neurobiología Celular y Molecular. Instituto de Neurobiología. Universidad Nacional Autónoma de México, Campus Juriquilla. Boulevard Juriquilla #3001. Juriquilla, Querétaro; CP 76230, México.
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Ragu-Varman D, Macedo-Mendoza M, Labrada-Moncada FE, Reyes-Ortega P, Morales T, Martínez-Torres A, Reyes-Haro D. Anorexia increases microglial density and cytokine expression in the hippocampus of young female rats. Behav Brain Res 2019; 363:118-125. [PMID: 30690107 DOI: 10.1016/j.bbr.2019.01.042] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 01/07/2019] [Accepted: 01/25/2019] [Indexed: 12/26/2022]
Abstract
Anorexia by osmotic dehydration is an adaptive response to hypernatremia and hyperosmolaemia induced by ingestion of a hypertonic solution. Dehydration-induced anorexia (DIA) reproduces weight loss and avoidance of food, despite its availability. By using this model, we previously showed increased reactive astrocyte density in the rat dorsal hippocampus, suggesting a pro-inflammatory environment where microglia may play an important role. However, whether such anorexic condition increases a pro-inflammatory response is unknown. The aim of this study was to test if DIA increases microglial density in the dorsal hippocampus, as well as the expression of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 beta (IL-1β) in the hippocampus of young female rats. Our results showed that DIA significantly increased microglial density in CA2-CA3 and dentate gyrus (DG) but not in CA1. However, forced food restriction (FFR) only increased microglial density in the DG. Accordingly, the activated/resting microglia ratio was significantly increased in CA2-CA3 and DG, in DIA and FFR groups. Finally, western blot analysis showed increased expression of IBA1, TNF-α, IL-6 and IL-1β in the hippocampus of both experimental groups. We conclude that anorexia triggers increased reactive microglial density and expression of TNF-α, IL-6 and IL-1β; this environment may result in hippocampal neuroinflammation.
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Affiliation(s)
- Durairaj Ragu-Varman
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Mayra Macedo-Mendoza
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Francisco Emmanuel Labrada-Moncada
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Pamela Reyes-Ortega
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Teresa Morales
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Ataúlfo Martínez-Torres
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico
| | - Daniel Reyes-Haro
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Juriquilla, Querétaro, CP76230, Mexico.
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Guo F, Gao S, Xu L, Sun X, Zhang N, Gong Y, Luan X. Arcuate Nucleus Orexin-A Signaling Alleviates Cisplatin-Induced Nausea and Vomiting Through the Paraventricular Nucleus of the Hypothalamus in Rats. Front Physiol 2018; 9:1811. [PMID: 30618823 PMCID: PMC6304364 DOI: 10.3389/fphys.2018.01811] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 12/04/2018] [Indexed: 01/06/2023] Open
Abstract
The most common side effects of cisplatin chemotherapy are nausea and vomiting, and the overwhelming majority of research studies on the mechanism of cisplatin-induced nausea have been focused on the “vomiting center.” As a modulatory center of gastric motility, the roles of the hypothalamus in nausea and vomiting remain unclear. In the present study, we investigated the effects of exogenous orexin-A injected into the arcuate nucleus (ARC) on cisplatin-induced nausea and vomiting, and the possible underlying mechanism. Kaolin intake was calculated daily in cisplatin-treated and saline-treated rats. Gastric motility recording, injections into the ARC, and lesions of the paraventricular nucleus (PVN) were used to study the effects of orexin-A and the hypothalamic nucleus on disorders of gastrointestinal function in cisplatin-treated rats. The pathway from the ARC to the PVN was observed through Fluoro-Gold retrograde tracing. Furthermore, an NPY Y1 receptor antagonist was administered to explore the possible mechanisms involved in the effects of orexin-A in the ARC. We illustrated that exogenous orexin-A injected into the ARC reduced kaolin intake and promoted gastric motility in cisplatin-treated rats, and these effects could have been blocked by an ipsilateral PVN lesion or co-injected antagonist of orexin-A-SB334867. Additional results showed that orexin-A-activated neurons in the ARC communicated directly with other neurons in the PVN that express neuropeptide Y (NPY). Furthermore, activation of the downstream NPY pathway was required for the observed effects of orexin in the ARC on cisplatin-induced nausea and vomiting. These findings reveal a novel neurobiological circuit from the ARC to the PVN that might provide a potential target for the prevention and treatment of cisplatin-induced nausea and vomiting.
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Affiliation(s)
- Feifei Guo
- Pathophysiology Department, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Shengli Gao
- Pathophysiology Department, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Luo Xu
- Pathophysiology Department, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Xiangrong Sun
- Pathophysiology Department, School of Basic Medicine, Qingdao University, Qingdao, China
| | - Nana Zhang
- Department of Clinical Laboratory, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yanling Gong
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, China
| | - Xiao Luan
- Pathophysiology Department, School of Basic Medicine, Qingdao University, Qingdao, China
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García-Luna C, Soberanes-Chávez P, de Gortari P. Impaired hypothalamic cocaine- and amphetamine-regulated transcript expression in lateral hypothalamic area and paraventricular nuclei of dehydration-induced anorexic rats. J Neuroendocrinol 2017; 29. [PMID: 28984394 DOI: 10.1111/jne.12541] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/14/2017] [Accepted: 10/02/2017] [Indexed: 11/28/2022]
Abstract
Negative energy balance promotes physiological adaptations that ensure the survival of animals. The hypothalamic-pituitary-thyroid axis regulates basal energy expenditure and its down-regulating adaptation to negative energy balance is well described: in fasting, the serum content of thyrotrophin (TSH) and thyroid hormones (TH) decreases, enhancing the survival odds of individuals. By contrast, dehydration-induced anorexic (DIA) rats present an impaired hypothalamic-pituitary-thyroid (HPT) axis adaptation despite their negative energy balance: increased circulating TSH levels. The implication of cocaine- and amphetamine-regulated transcript (CART), an anorexic peptide, in HPT axis function impairment and food-avoidance behaviour displayed by DIA animals is unknown. Because CART is co-expressed with the peptide that regulates the HPT axis in hypophysiotrophic paraventricular nucleus (PVN) neurones (TSH-releasing hormone), we analysed CART expression and possible implications with respect to high TSH levels of DIA animals. We examined whether changes in CART expression from the lateral hypothalamic area (LHA) and arcuate nucleus (ARC) could participate in food-avoidance of DIA rats. DIA and forced-food restricted (FFR) animals reduced their body weight and food intake. FFR rats had a down-regulation of their HPT axis (reduced serum TH and TSH content), whereas DIA animals had reduced TH but increased TSH levels. CART mRNA expression in the ARC decreased similarly between experimental groups and diminished in anterior, medial PVN and in LHA of FFR animals, whereas DIA animals showed unchanged levels. This impaired CART mRNA expression in the anterior PVN and LHA could be related to the aberrant feeding behaviour of DIA rats but not to their deregulated HPT axis function.
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Affiliation(s)
- C García-Luna
- Molecular Neurophysiology Laboratory, Department of Neurosciences Research, National Institute of Psychiatry Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - P Soberanes-Chávez
- Molecular Neurophysiology Laboratory, Department of Neurosciences Research, National Institute of Psychiatry Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - P de Gortari
- Molecular Neurophysiology Laboratory, Department of Neurosciences Research, National Institute of Psychiatry Ramón de la Fuente Muñiz, Mexico City, Mexico
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11
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Yoshimura M, Uezono Y, Ueta Y. Anorexia in human and experimental animal models: physiological aspects related to neuropeptides. J Physiol Sci 2015; 65:385-95. [PMID: 26123258 PMCID: PMC10717229 DOI: 10.1007/s12576-015-0386-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/16/2015] [Indexed: 01/20/2023]
Abstract
Anorexia, a loss of appetite for food, can be caused by various physiological and pathophysiological conditions. In this review, firstly, clinical aspects of anorexia nervosa are summarized in brief. Secondly, hypothalamic neuropeptides responsible for feeding regulation in each hypothalamic nucleus are discussed. Finally, three different types of anorexigenic animal models; dehydration-induced anorexia, cisplatin-induced anorexia and cancer anorexia-cachexia, are introduced. In conclusion, hypothalamic neuropeptides may give us novel insight to understand and find effective therapeutics strategy essential for various kinds of anorexia.
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Affiliation(s)
- Mitsuhiro Yoshimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555 Japan
| | - Yasuhito Uezono
- Division of Cancer Pathophysiology, National Cancer Center Research Institute, Tokyo, 104-0045 Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, 807-8555 Japan
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Méquinion M, Chauveau C, Viltart O. The use of animal models to decipher physiological and neurobiological alterations of anorexia nervosa patients. Front Endocrinol (Lausanne) 2015; 6:68. [PMID: 26042085 PMCID: PMC4436882 DOI: 10.3389/fendo.2015.00068] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/15/2015] [Indexed: 12/18/2022] Open
Abstract
Extensive studies were performed to decipher the mechanisms regulating feeding due to the worldwide obesity pandemy and its complications. The data obtained might be adapted to another disorder related to alteration of food intake, the restrictive anorexia nervosa. This multifactorial disease with a complex and unknown etiology is considered as an awful eating disorder since the chronic refusal to eat leads to severe, and sometimes, irreversible complications for the whole organism, until death. There is an urgent need to better understand the different aspects of the disease to develop novel approaches complementary to the usual psychological therapies. For this purpose, the use of pertinent animal models becomes a necessity. We present here the various rodent models described in the literature that might be used to dissect central and peripheral mechanisms involved in the adaptation to deficient energy supplies and/or the maintenance of physiological alterations on the long term. Data obtained from the spontaneous or engineered genetic models permit to better apprehend the implication of one signaling system (hormone, neuropeptide, neurotransmitter) in the development of several symptoms observed in anorexia nervosa. As example, mutations in the ghrelin, serotonin, dopamine pathways lead to alterations that mimic the phenotype, but compensatory mechanisms often occur rendering necessary the use of more selective gene strategies. Until now, environmental animal models based on one or several inducing factors like diet restriction, stress, or physical activity mimicked more extensively central and peripheral alterations decribed in anorexia nervosa. They bring significant data on feeding behavior, energy expenditure, and central circuit alterations. Animal models are described and criticized on the basis of the criteria of validity for anorexia nervosa.
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Affiliation(s)
- Mathieu Méquinion
- INSERM UMR-S1172, Development and Plasticity of Postnatal Brain, Lille, France
| | - Christophe Chauveau
- Pathophysiology of Inflammatory Bone Diseases, EA 4490, University of the Littoral Opal Coast, Boulogne sur Mer, France
| | - Odile Viltart
- INSERM UMR-S1172, Early stages of Parkinson diseases, University Lille 1, Lille, France
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13
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Machaalani R, Hunt NJ, Waters KA. Effects of changes in energy homeostasis and exposure of noxious insults on the expression of orexin (hypocretin) and its receptors in the brain. Brain Res 2013; 1526:102-22. [PMID: 23830852 DOI: 10.1016/j.brainres.2013.06.035] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/19/2013] [Accepted: 06/25/2013] [Indexed: 12/23/2022]
Abstract
This review summarizes data regarding the brain expression of the orexin (hypocretin) system including: prepro-orexin (PPO), orexin A (OxA), orexin B (OxB) and the two orexin receptors 1 and 2 (OxR1, OxR2). Clinical data is limited to OxA and OxB in cerebral spinal fluid and serum/plasma, thus necessitating the development of animal models to undertake mechanistic studies. We focus on changes in animal models that were either exposed to a regime of altered sleep, metabolic energy homeostasis, exposed to drugs and noxious insults. Many more expressional studies are available for PPO, OxA and OxB levels, compared to studies of the receptors. Interestingly, the direction and pattern of change for PPO, OxA and OxB is inconsistent amongst studies, whereas for the receptors, there tends to be increased expression for both OxR1 and OxR2 after alterations in energy homeostasis, and an increased expression after noxious insults or exposure to some drugs. The clinical implications of these results from animal models are discussed in light of the findings from human studies, and future research directions are suggested to fill knowledge gaps with regard to the orexin system, particularly during early brain development.
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Affiliation(s)
- Rita Machaalani
- Department of Medicine, Blackburn Building, DO6, University of Sydney, NSW 2006, Australia.
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14
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Alvarez-Salas E, Aceves C, Anguiano B, Uribe RM, García-Luna C, Sánchez E, de Gortari P. Food-restricted and dehydrated-induced anorexic rats present differential TRH expression in anterior and caudal PVN. Role of type 2 deiodinase and pyroglutamyl aminopeptidase II. Endocrinology 2012; 153:4067-76. [PMID: 22719053 DOI: 10.1210/en.2011-2011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TRH synthesized in hypothalamic paraventricular nucleus (PVN) regulates thyroid axis function and is also implicated in anorexigenic effects. Under energy deficit, animals present decreased PVN TRH expression and release, low TSH levels, and increased appetite. Dehydration-induced anorexia (DIA) model allows insight into underlying mechanisms of feeding regulation. Animals drinking a 2.5% NaCl solution for 7 d present body weight reduction; despite their negative energy balance, they avoid food and have increased PVN TRH expression and TSH serum levels. These findings support an inhibiting role of PVN TRH in feeding control. We compared TRH expression by in situ hybridization in PVN subdivisions of 7-d dehydrated male rats to those of a pair-fed group (forced food-restricted) with similar metabolic changes than DIA, but motivated to eat, and to controls. We measured peripheral deiodinase activities, and expression and activity of medial basal hypothalamic type 2 deiodinase and pyroglutamyl-aminopeptidase II, to understand their regulating role in PVN TRH changes between food restriction and anorexia. TRH mRNA levels increased in anterior (aPVN) and medial-caudal subdivisions in DIA rats, whereas it decreased in medial PVN in both experimental groups. We confirmed the nonhypophysiotropic nature of aPVN TRHergic cells by injecting ip fluorogold tracer. Findings support a subspecialization of TRHergic hypophysiotrophic cells that responded differently between anorexic and food-restricted animals; also, that aPVN TRH participates in food intake regulation. Increased type 2 deiodinase activity seemed responsible for low medial PVN TRH synthesis, whereas increased medial basal hypothalamic pyroglutamyl-aminopeptidase II activity in DIA rats might counteract their high TRH release.
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Affiliation(s)
- E Alvarez-Salas
- Neurofisiología Molecular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz (INPRFM), México D.F., México
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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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16
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Vucetic Z, Kimmel J, Totoki K, Hollenbeck E, Reyes TM. Maternal high-fat diet alters methylation and gene expression of dopamine and opioid-related genes. Endocrinology 2010; 151:4756-64. [PMID: 20685869 PMCID: PMC2946145 DOI: 10.1210/en.2010-0505] [Citation(s) in RCA: 372] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Maternal obesity during pregnancy increases the risk of obesity in the offspring. Obesity, arising from an imbalance of energy intake and expenditure, can be driven by the ingestion of palatable [high fat (HF), high sugar], energy-dense foods. Dopamine and opioid circuitry are neural substrates associated with reward that can affect animals' preference for palatable foods. Using a mouse model, the long-term effect of maternal consumption of a HF diet on dopamine and opioid gene expression within the mesocorticolimbic reward circuitry and hypothalamus of the offspring was investigated. Mice from dams fed a HF diet during pregnancy and lactation showed an increased preference for sucrose and fat. Gene expression, measured using quantitative real-time PCR, revealed a significant approximately 3- to 10-fold up-regulation of dopamine reuptake transporter (DAT) in the ventral tegmental area, nucleus accumbens, and prefrontal cortex and a down-regulation of DAT in the hypothalamus. Additionally, expression of both μ-opioid receptor (MOR) and preproenkephalin (PENK) was increased in nucleus accumbens, prefrontal cortex, and hypothalamus of mice from dams that consumed the HF diet. Epigenetic mechanisms have been associated with long-term programming of gene expression after various in utero insults. We observed global and gene-specific (DAT, MOR, and PENK) promoter DNA hypomethylation in the brains of offspring from dams that consumed the HF diet. These data demonstrate that maternal consumption of a HF diet can change the offsprings' epigenetic marks (DNA hypomethylation) in association with long-term alterations in gene expression (dopamine and opioids) and behavior (preference for palatable foods).
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Affiliation(s)
- Zivjena Vucetic
- University of Pennsylvania School of Medicine, Department of Pharmacology, Institute for Translational Medicine and Therapeutics, School of Medicine, 805 Biomedical Research Building II/III, 421 Curie Boulevard, Philadelphia, Pennsylvania 19104-6160, USA
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