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Muraro EN, Sbardelotto BM, Guareschi ZM, de Almeida W, Souza Dos Santos A, Grassiolli S, Centenaro LA. Vitamin D supplementation combined with aerobic physical exercise restores the cell density in hypothalamic nuclei of rats exposed to monosodium glutamate. Clin Nutr ESPEN 2022; 52:20-27. [PMID: 36513455 DOI: 10.1016/j.clnesp.2022.09.009] [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: 02/07/2022] [Revised: 08/29/2022] [Accepted: 09/07/2022] [Indexed: 01/28/2023]
Abstract
BACKGROUND & AIMS In view of the increase in the prevalence of obesity and metabolic syndrome in childhood and adolescence, this study proposed the early and combined use of treatments to restore brain areas related to satiety. The vitamin D supplementation, aerobic exercise and the combination of these interventions on the structure of arcuate (ARC) and ventromedial (VMH) nuclei of hypothalamus were investigated in monosodium glutamate (MSG)-treated rats. METHODS Wistar rats were separated into five groups: Control group (CT); Obese group injected with MSG (OB); Obese group supplemented with vitamin D (OBvd); Obese group submitted to forced swimming training (OBexe) and Obese group treated with vitamin D supplementation and forced swimming training (OBvd + exe). RESULTS In the OB group, the visceral fat weight was significantly higher, there was a reduction in the number of glial cells in the ARC nucleus and also in the number of neurons in the ARC and VMH nuclei. Aerobic exercise was able to reduce the visceral fat weight in the OBexe group. The combination of treatments used in the OBvd + exe group reversed the loss of neurons and glial cells produced by MSG in the ARC nucleus. All treated groups exhibited a higher number of neurons in VMH nucleus, but an increase in the glial cells were observed only in the OBexe and OBvd + exe groups. CONCLUSIONS The effectiveness of obesity treatment can be favored through the early and combined use of vitamin D supplementation and aerobic exercise, since these therapies are able to restore brain nuclei involved in the control of food intake.
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Affiliation(s)
- Eduardo Natan Muraro
- Laboratório de Morfologia Experimental, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Bruno Marques Sbardelotto
- Laboratório de Morfologia Experimental, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Zoé Maria Guareschi
- Laboratório de Fisiologia Endócrina e Metabólica, Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Wellington de Almeida
- Laboratório de Morfologia Experimental, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Adriana Souza Dos Santos
- Laboratório de Morfologia Experimental, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Sabrina Grassiolli
- Laboratório de Fisiologia Endócrina e Metabólica, Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
| | - Lígia Aline Centenaro
- Laboratório de Morfologia Experimental, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, Rua Universitária, 1619, Cascavel, Paraná, CEP: 85819-110, Brazil.
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Gürgen SG, Sayın O, Çeti̇n F, Sarsmaz HY, Yazıcı GN, Umur N, Yücel AT. The Effect of Monosodium Glutamate on Neuronal Signaling Molecules in the Hippocampus and the Neuroprotective Effects of Omega-3 Fatty Acids. ACS Chem Neurosci 2021; 12:3028-3037. [PMID: 34328736 DOI: 10.1021/acschemneuro.1c00308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Monosodium glutamate (MSG) is a flavoring substance added to many ready-to-eat foods and has known neurotoxic effects. This study was performed in order to examine the potential toxic effect of MSG on neurons in various regions of the hippocampus in prepubertal rats. It also investigated the protective effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on brain-derived neurotropic factor (BDNF), n-methyl-d-aspartate receptor (NMDA-R), and neuropeptide-Y (NPY) expression in the brain, using immunohistochemical and biochemical methods. Six female prepubertal Wistar albino rats were used in each group. Group 1, the control group, received 0.9% saline solution subcutaneously (sc) on days 1, 3, 5, 7, and 9. Group 2 received 4 mg/g MSG sc on days 1, 3, 5, 7, and 9. Group 3 received MSG + EPA (4 mg/g sc on days 1, 3, 5, 7, and 9. Oral 300 mg/kg for 9 d), while Group 4 received MSG + DHA (4 mg/g sc on days 1, 3, 5, 7, and 9 and 300 mg/kg orally for 9 d, respectively). At the end of the ninth day the hippocampal regions of the brain were removed and either fixed for immunohistochemical staining or stored at -80 °C for biochemical parameter investigation. BDNF, NMDA-R, and NPY expression results were evaluated using immunohistochemistry and an enzyme-linked immunosorbent assay. According to our findings, neurons in the control group hippocampal CA1 and DG regions exhibited strong BDNF, NPY, and NMDA-R reactions, while an expression in both regions decreased in the MSG group (p < 0.00). However, in the MSG-EPA and MSG-DHA groups, BDNF, NPY, and NMDA-R immunoreactions in neurons in the same region were similar to those of the control group (p = 0.00). No significant difference was observed in terms of expression in hippocampal neurons between the MSG-EPA and MSG-DHA groups (p > 0.00). In conclusion, since MSG caused a decrease in BDNF, NMDA-R, and NPY neural signaling molecules in the CA1 and DG regions of the hippocampus of prepubertal rats compared to the control group, care is required over the consumption of MSG, since it may affect memory-related neurons in these age groups. In addition, we concluded that the use of omega-3 fatty acids such as EPA and DHA in addition to MSG may protect against the neurotoxic effects of MSG.
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Affiliation(s)
- Seren Gülşen Gürgen
- Department of Histology and Embryology, School of Vocational Health Service, Manisa Celal Bayar University, Manisa 45140, Turkey
| | - Oya Sayın
- Department of Biochemistry, School of Vocational Health Service, Dokuz Eylul University, İzmir 35330, Turkey
| | - Ferihan Çeti̇n
- Department of Physiology, Faculty of Medicine, Istanbul Medeniyet University, Istanbul 34700, Turkey
| | - Hayrunnisa Yeşil Sarsmaz
- Department of Histology and Embryology, Faculty of Health Science, Manisa Celal Bayar University, Manisa 45140, Turkey
| | - Gülce Naz Yazıcı
- Department of Histology and Embryology, Faculty of Medicine, Erzincan University, Erzincan 24100, Turkey
| | - Nurcan Umur
- Department of Molecular Biology, School of Vocational Health Service, Manisa Celal Bayar University, Manisa 45140, Turkey
| | - Ayşe Tuç Yücel
- Department of Anatomy, School of Vocational Health Service, Manisa Celal Bayar University, Manisa 45140, Turkey
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Alves PL, Abdalla FMF, Alponti RF, Silveira PF. Anti-obesogenic and hypolipidemic effects of a glucagon-like peptide-1 receptor agonist derived from the saliva of the Gila monster. Toxicon 2017; 135:1-11. [PMID: 28579479 DOI: 10.1016/j.toxicon.2017.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 05/31/2017] [Accepted: 06/01/2017] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Glucagon-like peptide-1 (GLP-1) receptor (R) agonists are a class of incretin mimetic drugs that have been used for the treatment of type 2 diabetes mellitus and also considered strong candidates for the treatment of obesity. The original prototypical drug in this class is the exenatide, a synthetic peptide with the same structure as the native molecule, exendin-4, found in the saliva of the Gila monster (Heloderma suspectum suspectum lizard). OBJECTIVES To identify and compare the anti-obesogenic, antidyslipidemic and antidiabetogenic effects of agonism in GLP-1R by exenatide on two distinct models of obesity: induced by hypothalamic injury (MSG) or high-calorie diet (DIO). METHODS To obtain MSG, neonatal rats were daily subcutaneously injected with 4 g monosodium glutamate/kg, for 10 consecutive days. To obtain DIO, 72-75 days old rats received hyperlipid food and 30% sucrose for drinking up to 142-145 days old. Untreated healthy rats with the same age were used as control. General biometric and metabolic parameters were measured. RESULTS MSG was characterized by decreased naso-anal length, food and fluid intake, plasma protein and glucose decay rate per minute after insulin administration (KITT), as well as increased Lee index (body mass0.33/naso-anal length), mass of retroperitoneal and periepididymal fat pads, glycemia, triglycerides (TG), LDL and VLDL. Exenatide ameliorated KITT and food and fluid intake, and it also restored glycemia in MSG. DIO was characterized by glucose intolerance, increased body mass, Lee index, fluid intake, mass of retroperitoneal and periepididymal fat pads, glycemia, glycated hemoglobin (HbA1c), TG, VLDL and total cholesterol, as well as decreased food intake and KITT. Exenatide restored glycemia, HbA1c, TG, VLDL, total cholesterol and body mass, and it also ameliorated food and fluid intake, KITT and mass of retroperitoneal fat pad in DIO. CONCLUSIONS The hypothalamic injury and the high-calorie diet induce dyslipidemia and glycemic dysregulation in addition to obesity in rats. The usual therapeutic dose of exenatide in humans is antidiabetogenic in both these obesity models, but is anti-obesogenic and hypolipidemic only in diet-induced obesity. Agonists of GLP-1R are promising anti-obesogenic and antidyslipidemic drugs in the early stages of the obesity, in which the integrity of the nervous system was unaffected.
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Affiliation(s)
- Patricia Lucio Alves
- Laboratory of Pharmacology, Unit of Translational Endocrine Physiology, Instituto Butantan, Sao Paulo, Brazil
| | | | - Rafaela Fadoni Alponti
- Laboratory of Pharmacology, Unit of Translational Endocrine Physiology, Instituto Butantan, Sao Paulo, Brazil
| | - Paulo Flavio Silveira
- Laboratory of Pharmacology, Unit of Translational Endocrine Physiology, Instituto Butantan, Sao Paulo, Brazil.
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Teubner BJW, Leitner C, Thomas MA, Ryu V, Bartness TJ. An intact dorsomedial posterior arcuate nucleus is not necessary for photoperiodic responses in Siberian hamsters. Horm Behav 2015; 70:22-9. [PMID: 25647158 PMCID: PMC4409532 DOI: 10.1016/j.yhbeh.2014.12.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 12/22/2014] [Accepted: 12/23/2014] [Indexed: 01/29/2023]
Abstract
Seasonal responses of many animal species are triggered by changes in daylength and its transduction into a neuroendocrine signal by the pineal gland through the nocturnal duration of melatonin (MEL) release. The precise central sites necessary to receive, transduce, and relay the short day (SD) fall-winter MEL signals into seasonal responses and changes in physiology and behavior are unclear. In Siberian hamsters, SDs trigger decreases in body and lipid mass, testicular regression and pelage color changes. Several candidate genes and their central sites of expression have been proposed as components of the MEL transduction system with considerable recent focus on the arcuate nucleus (ARC) and its component, the dorsomedial posterior arcuate nucleus (dmpARC). This site has been postulated as a critical relay of SD information through the modulation of a variety of neurochemicals/receptors important for the control of energy balance. Here the necessity of an intact dmpARC for SD responses was tested by making electrolytic lesions of the Siberian hamster dmpARC and then exposing them to either long days (LD) or SDs for 12wks. The SD typical decreases in body and fat mass, food intake, testicular volume, serum testosterone concentrations, pelage color change and increased UCP-1 protein expression (a proxy for brown adipose tissue thermogenesis) all occurred despite the lack of an intact dmpARC. Although the Siberian hamster dmpARC contains photoperiod-modulated constituents, these data demonstrate that an intact dmpARC is not necessary for SD responses and not integral to the seasonal energy- and reproductive-related responses measured here.
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Affiliation(s)
- Brett J W Teubner
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA 30302-4010, USA
| | - Claudia Leitner
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA 30302-4010, USA
| | - Michael A Thomas
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA 30302-4010, USA
| | - Vitaly Ryu
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA 30302-4010, USA
| | - Timothy J Bartness
- Department of Biology and Center for Obesity Reversal, Georgia State University, Atlanta, GA 30302-4010, USA.
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Serological and Histological Examination of a Nonalcoholic Steatohepatitis Mouse Model Created via the Administration of Monosodium Glutamate. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:725351. [PMID: 27433515 PMCID: PMC4897218 DOI: 10.1155/2014/725351] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/16/2014] [Accepted: 07/31/2014] [Indexed: 01/29/2023]
Abstract
The administration of monosodium glutamate (MSG) to mice induces hepatic steatosis and inflammation. In this study, we investigated the metabolic features of MSG-treated mice and the histological changes that occur in their livers and adipose tissue. MSG mice were prepared by subcutaneously injecting MSG into newborn C57BL/6J male mice. The control mice were subcutaneously injected with saline. Another group of mice was fed a methionine- and choline-deficient diet (MCD). Compared with the control mice, the MSG mice had higher serum levels of insulin and cholesterol than the control mice, whereas the opposite was true for the MCD mice. Microvesicular steatosis and inflammatory cell infiltration were detected in both the MSG and MCD mouse livers. Enlarged adipocytes and crown-like structures were observed in the epididymal fat of the MSG mice, whereas neither of these features was seen in the MCD mice. Flow cytometric analysis revealed increased frequencies of monocytes and M1 macrophages in the livers and epididymal fat tissue of the MSG mice, respectively. The MSG mice exhibited the characteristic liver histopathology of nonalcoholic steatohepatitis (NASH) as well as metabolic syndrome-like features, which suggested that MSG mice are a better model of human NASH than MCD mice.
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Coordinated regulation of hepatic energy stores by leptin and hypothalamic agouti-related protein. J Neurosci 2013; 33:11972-85. [PMID: 23864684 DOI: 10.1523/jneurosci.0830-13.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Like obesity, prolonged food deprivation induces severe hepatic steatosis; however, the functional significance of this phenomenon is not well understood. In this study, we show that the fall in plasma leptin concentration during fasting is required for the development of hepatic steatosis in mice. Removal of leptin receptors from AGRP neurons diminishes fasting-induced hepatic steatosis. Furthermore, the suppressive effects of leptin on fasting-induced hepatic steatosis are absent in mice lacking the gene encoding agouti-related protein (Agrp), suggesting that this function of leptin is mediated by AGRP. Prolonged fasting leads to suppression of hepatic sympathetic activity, increased expression of acyl CoA:diacylglycerol acyltransferase-2 in the liver, and elevation of hepatic triglyceride content and all of these effects are blunted in the absence of AGRP. AGRP deficiency, despite having no effects on feeding or body adiposity in the free-fed state, impairs triglyceride and ketone body release from the liver during prolonged fasting. Furthermore, reducing CNS Agrp expression in wild-type mice by RNAi protected against the development of hepatic steatosis not only during starvation, but also in response to consumption of a high-fat diet. These findings identify the leptin-AGRP circuit as a critical modulator of hepatic triglyceride stores in starvation and suggest a vital role for this circuit in sustaining the supply of energy from the liver to extrahepatic tissues during periods of prolonged food deprivation.
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Bruinstroop E, Pei L, Ackermans MT, Foppen E, Borgers AJ, Kwakkel J, Alkemade A, Fliers E, Kalsbeek A. Hypothalamic neuropeptide Y (NPY) controls hepatic VLDL-triglyceride secretion in rats via the sympathetic nervous system. Diabetes 2012; 61:1043-50. [PMID: 22461566 PMCID: PMC3331766 DOI: 10.2337/db11-1142] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Excessive secretion of triglyceride-rich very low-density lipoproteins (VLDL-TG) contributes to diabetic dyslipidemia. Earlier studies have indicated a possible role for the hypothalamus and autonomic nervous system in the regulation of VLDL-TG. In the current study, we investigated whether the autonomic nervous system and hypothalamic neuropeptide Y (NPY) release during fasting regulates hepatic VLDL-TG secretion. We report that, in fasted rats, an intact hypothalamic arcuate nucleus and hepatic sympathetic innervation are necessary to maintain VLDL-TG secretion. Furthermore, the hepatic sympathetic innervation is necessary to mediate the stimulatory effect of intracerebroventricular administration of NPY on VLDL-TG secretion. Since the intracerebroventricular administration of NPY increases VLDL-TG secretion by the liver without affecting lipolysis, its effect on lipid metabolism appears to be selective to the liver. Together, our findings indicate that the increased release of NPY during fasting stimulates the sympathetic nervous system to maintain VLDL-TG secretion at a postprandial level.
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Affiliation(s)
- Eveline Bruinstroop
- Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, the Netherlands.
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Teubner BJW, Keen-Rhinehart E, Bartness TJ. Third ventricular coinjection of subthreshold doses of NPY and AgRP stimulate food hoarding and intake and neural activation. Am J Physiol Regul Integr Comp Physiol 2011; 302:R37-48. [PMID: 22012701 DOI: 10.1152/ajpregu.00475.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We previously demonstrated that 3rd ventricular (3V) neuropeptide Y (NPY) or agouti-related protein (AgRP) injection potently stimulates food foraging/hoarding/intake in Siberian hamsters. Because NPY and AgRP are highly colocalized in arcuate nucleus neurons in this and other species, we tested whether subthreshold doses of NPY and AgRP coinjected into the 3V stimulates food foraging, hoarding, and intake, and/or neural activation [c-Fos immunoreactivity (c-Fos-ir)] in hamsters housed in a foraging/hoarding apparatus. In the behavioral experiment, each hamster received four 3V treatments by using subthreshold doses of NPY and AgRP for all behaviors: 1) NPY, 2) AgRP, 3) NPY+AgRP, and 4) saline with a 7-day washout period between treatments. Food foraging, intake, and hoarding were measured 1, 2, 4, and 24 h and 2 and 3 days postinjection. Only when NPY and AgRP were coinjected was food intake and hoarding increased. After identical treatment in separate animals, c-Fos-ir was assessed at 90 min and 14 h postinjection, times when food intake (0-1 h) and hoarding (4-24 h) were uniquely stimulated. c-Fos-ir was increased in several hypothalamic nuclei previously shown to be involved in ingestive behaviors and the central nucleus of the amygdala (CeA), but only in NPY+AgRP-treated animals (90 min and 14 h: magno- and parvocellular regions of the hypothalamic paraventricular nucleus and perifornical area; 14 h only: CeA and sub-zona incerta). These results suggest that NPY and AgRP interact to stimulate food hoarding and intake at distinct times, perhaps released as a cocktail naturally with food deprivation to stimulate these behaviors.
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Affiliation(s)
- Brett J W Teubner
- Department of Biology, Georgia State University, Atlanta, 30302-4010, USA
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Vaughan CH, Shrestha YB, Bartness TJ. Characterization of a novel melanocortin receptor-containing node in the SNS outflow circuitry to brown adipose tissue involved in thermogenesis. Brain Res 2011; 1411:17-27. [PMID: 21802070 DOI: 10.1016/j.brainres.2011.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 07/01/2011] [Indexed: 11/19/2022]
Abstract
The melanocortins (MC) can affect interscapular brown adipose tissue (IBAT) thermogenesis via its sympathetic nervous system (SNS) innervation. We chose a site of high MC4-receptor (MC4-R) mRNA co-localization with SNS outflow neurons to IBAT, the subzona incerta (subZI) to test whether IBAT thermogenesis could be increased or decreased. We first performed immunohistochemical characterization of the subZI and found neurons and/or fibers in this area positive for melanin concentrating hormone, oxytocin, arginine vasopressin, agouti-related protein and alpha-melanocyte stimulating hormone. Functional characterization of the subZI was tested via site-specific microinjections. The MC3/4-R agonist, melanotan II [MTII (0.025, 0.05 and 0.075nmol)], and specific MC4-R agonist (cyclo [ß-Ala-His-D-Phe-Arg-Trp-Glu]-NH2; 0.024nmol) both significantly increased IBAT temperature (T(IBAT)) and pretreatment with the MC4R antagonist, HS024 (0.072nmol) blocked the MC4-R agonist-induced increased T(IBAT) in conscious, freely-moving Siberian hamsters. Injection of the MC4-R antagonist alone significantly decreased T(IBAT) up to 3h post injection. Collectively, these results highlight the identification of a brain area that possesses high concentrations of MC4-R mRNA and SNS outflow neurons to IBAT that has not been previously reported to be involved in the control of T(IBAT). These results add to previously identified neural nodes that are components of the central circuits controlling thermogenesis.
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MESH Headings
- Adipose Tissue, Brown/innervation
- Adipose Tissue, Brown/physiology
- Animals
- Arginine Vasopressin/pharmacology
- Cricetinae
- Dose-Response Relationship, Drug
- Immunohistochemistry
- Male
- Microinjections
- Phenotype
- Phodopus
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/antagonists & inhibitors
- Receptors, Melanocortin/agonists
- Receptors, Melanocortin/antagonists & inhibitors
- Receptors, Melanocortin/physiology
- Stereotaxic Techniques
- Sympathetic Nervous System/metabolism
- Telemetry
- Thermogenesis/physiology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- C H Vaughan
- Department of Biology, Center for Obesity Reversal, Georgia State University,Atlanta, GA, 30302-4010, USA
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Elfers C, Ralston M, Roth CL. Studies of different female rat models of hypothalamic obesity. J Pediatr Endocrinol Metab 2011; 24:131-7. [PMID: 21648279 DOI: 10.1515/jpem.2011.098] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Hypothalamic obesity (HO) is a major and unsolved problem in patients with medial hypothalamic lesions and is associated with hyperinsulinemia and hyperleptinemia. The purpose of this study was to create a rodent model that mimics metabolic changes in HO for use in therapeutic testing. Female Sprague-Dawley rats were used to test the individual and combined effects of two types of medial hypothalamic lesions: arcuate nucleus (ARC) lesions by injection of monosodium glutamate at neonatal age, and ventromedial nucleus (VMN) lesions by passing an anodal current through an electrode placed in the VMN at age 80 days. Adiposity in ARC-lesioned animals was associated with decreased food intake and stunted growth, while VMN lesions were associated with hyperphagia but not reduced growth. The greatest weight gain (weight at age 200 days 712 +/- 65 vs. 451 +/- 19 g in controls), hyperphagia (food intake 10 days following surgery 33 +/- 0.8 vs. 18.5 +/- 0.7 g/day in sham-treated rats), hyperinsulinemia and hyperleptinemia occurred in rats that received both ARC and VMN lesions. Thus, the combined medial hypothalamic lesions result in an obesity phenotype similar to that of patients that suffer from HO and are consequently more suitable for testing potential therapeutics for this disorder than lesions of single hypothalamic nuclei.
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Affiliation(s)
- Clinton Elfers
- Seattle Children's Research Institute, Center of Integrative Brain Research, University of Washington, Seattle, WA 98101, USA
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Elfers CT, Roth CL. Effects of methylphenidate on weight gain and food intake in hypothalamic obesity. Front Endocrinol (Lausanne) 2011; 2:78. [PMID: 22649386 PMCID: PMC3355874 DOI: 10.3389/fendo.2011.00078] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/06/2011] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED For patients with a craniopharyngioma (CP), treatment of hypothalamic obesity (HO) and hyperphagia following resection and/or radiotherapy is extremely difficult and few reports have been published on potential drug therapies. Psychomotor stimulant methylphenidate (MPH) has been reported to inhibit food intake (FI). In this paper, we report reduction of body mass index (BMI) and appetite in an adolescent CP patient suffering from HO. We then tested the ability of MPH to attenuate the FI and body weight (BW) gain in a rat model consistent with the neuroanatomical and metabolic disturbances commonly observed in obese CP patients. Specifically, we used a novel electrolytically generated combined medial hypothalamic lesion (CMHL) affecting the arcuate nucleus, ventromedial hypothalamic nucleus, and dorsomedial hypothalamic nucleus to induce hyperphagia, rapid weight gain, and adiposity. Both CMHL and control animals (n = 7 per group) were administered either methylphenidate HCl (MPH; 20 mg kg(-1) day(-1)) or saline for 4 days in a crossover design experiment 28 weeks post-surgery. A significant decrease in percent baseline FI (CMHL -23%, p = 0.008; control -20%, p = 0.002) and percent change in BW (CMHL -1.97%/4 days, p = 0.011; control -1.75%/4 days, p = 0.003) was observed during MPH treatment as compared to saline. CONCLUSION This study shows MPH treatment of severely obese CMHL rats resulted in significantly reduced FI and BW loss.
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Affiliation(s)
- Clinton Thomas Elfers
- Seattle Children’s Research Institute, Center for Integrative Brain Research, University of Washington, School of MedicineSeattle, WA, USA
| | - Christian Ludwig Roth
- Seattle Children’s Research Institute, Center for Integrative Brain Research, University of Washington, School of MedicineSeattle, WA, USA
- *Correspondence: Christian Ludwig Roth, Division of Endocrinology, Seattle Children’s Hospital Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, USA. e-mail:
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Leitner C, Bartness TJ. An intact dorsomedial hypothalamic nucleus, but not the subzona incerta or reuniens nucleus, is necessary for short-day melatonin signal-induced responses in Siberian hamsters. Neuroendocrinology 2011; 93:29-39. [PMID: 20847551 PMCID: PMC3066241 DOI: 10.1159/000320474] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 08/12/2010] [Indexed: 11/19/2022]
Abstract
Siberian hamsters provide a useful model to define mechanisms underlying obesity reversal as they naturally transition from their extreme seasonal obesity in long 'summer-like' days (LDs) to a leaner state in short 'winter-like' days (SDs). These day length changes are coded into durational melatonin (MEL) signals by the pineal gland resulting in stimulation of MEL receptors (MEL(1a)-Rs). MEL(1a)-R mRNA is colocalized centrally in sympathetic nervous system (SNS) outflow neurons comprising a chain of neurons that ultimately innervates white adipose tissue (WAT). Neural components in this circuit include the subzona incerta (subZI), dorsomedial hypothalamic nucleus (DMH) and thalamic reuniens nucleus (ReN). SD, long-duration MEL signals induce gonadal regression and increase WAT SNS drive triggering lipolysis and thereby reversing LD obesity. We attempted to block the reversal of SD MEL signal-induced obesity by making electrolytic or sham lesions of the subZI, ReN or DMH in LD-housed hamsters. To create SD-like, long-duration MEL signals, we injected MEL 3 h before lights out, thereby lengthening the naturally occurring nocturnal duration of circulating MEL. ReN and subZI lesions did not block SD-like MEL signal-induced decreases in body, WAT, testicular masses or food intake; by contrast, DMH lesions blocked decreases in WAT and testicular mass. This nonresponsiveness was not due to lesion-induced inappropriate nocturnal LD MEL secretion that would have altered our creation of SD-like signals. Therefore, the DMH appears to participate in the control of both SD energy and reproductive responses, and joins the suprachiasmatic nucleus as sites necessary for SD responses in this species.
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Affiliation(s)
| | - Timothy J. Bartness
- *Timothy J. Bartness, Department of Biology, Georgia State University, 24 Peachtree Ctr Ave NE, Atlanta, GA 30302-4010 (USA), Tel. +1 404 413 5334, Fax +1 404 413 5301, E-Mail
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Roth CL. Hypothalamic obesity in patients with craniopharyngioma: profound changes of several weight regulatory circuits. Front Endocrinol (Lausanne) 2011; 2:49. [PMID: 22654811 PMCID: PMC3356147 DOI: 10.3389/fendo.2011.00049] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 09/19/2011] [Indexed: 02/01/2023] Open
Abstract
One of the most striking examples of dysfunctional hypothalamic signaling of energy homeostasis is observed in patients with hypothalamic lesions leading to hypothalamic obesity (HO). This drastic condition is frequently seen in patients with craniopharyngioma (CP), an embryological tumor located in the hypothalamic and/or pituitary region, frequently causing not only hypopituitarism, but also leading to damage of medial hypothalamic nuclei due to the tumor and its treatment. HO syndrome in CP patients is characterized by fatigue, decreased physical activity, uncontrolled appetite, and morbid obesity, and is associated with insulin and leptin resistance. Mechanisms leading to the profoundly disturbed energy homeostasis are complex. This review summarizes different aspects of important clinical studies as well as data obtained in rodent studies. In addition a model is provided describing how medial hypothalamic lesion can interact simultaneously with several weight-regulating circuitries.
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Affiliation(s)
- Christian L. Roth
- Seattle Children’s Hospital Research InstituteSeattle, WA, USA
- *Correspondence: Christian L. Roth, Division of Endocrinology, Seattle Children’s Hospital Research Institute, 1900 Ninth Avenue, Seattle, WA 98101, USA. e-mail:
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Dietary trans-fat combined with monosodium glutamate induces dyslipidemia and impairs spatial memory. Physiol Behav 2010; 99:334-42. [DOI: 10.1016/j.physbeh.2009.11.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Revised: 11/16/2009] [Accepted: 11/20/2009] [Indexed: 01/21/2023]
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Dailey MJ, Bartness TJ. Arcuate nucleus destruction does not block food deprivation-induced increases in food foraging and hoarding. Brain Res 2010; 1323:94-108. [PMID: 20138163 DOI: 10.1016/j.brainres.2010.01.078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 01/26/2010] [Accepted: 01/27/2010] [Indexed: 11/29/2022]
Abstract
The mechanisms underlying the control of food intake are considerably better understood than those underlying the appetitive ingestive behaviors of foraging and hoarding of food, despite the prevalence of the latter across species including humans. Neuropeptide Y (NPY) and Agouti-related protein (AgRP), two orexigenic neuropeptides known to stimulate food intake in a variety of species, applied centrally to Siberian hamsters increases foraging and especially hoarding with lesser increases in food intake. Both are expressed in the arcuate nucleus (Arc) and their synthesis increases with food deprivation, a naturally-occurring stimulus that markedly increases foraging and hoarding in Siberian hamsters. Therefore, we tested whether destruction of Arc neurons blocks these ingestive behaviors. This was accomplished either by microinjecting NPY conjugated to saporin (NPY-SAP) bilaterally into the Arc to kill NPY receptor-bearing neurons or via neonatal monosodium glutamate (MSG) treatment. For both methods, Arc cresyl violet staining (cell density) and NPY and Y1 receptor-immunoreactivity (ir) were significantly decreased. Although baseline foraging and food hoarding were not affected, food deprivation-induced increased food hoarding was surprisingly exaggerated approximately 100% with both types of Arc destruction. We found a substantial amount of remaining NPY-ir fibers, likely emanating from the brainstem, and a significant up-regulation of Y1 receptors in Arc NPY projections areas (hypothalamic paraventricular nucleus and perifornical area) after Arc denervation and their activation may have accounted for the exaggerated increases. The converging evidence from both Arc destruction methods suggests an intact Arc is not necessary for food deprivation-induced increases in food foraging and hoarding.
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Affiliation(s)
- Megan J Dailey
- Department of Biology, Georgia State University, 24 Peachtree Center Ave NE, Atlanta, GA, 30302-4010, USA
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Leitner C, Bartness TJ. Acute brown adipose tissue temperature response to cold in monosodium glutamate-treated Siberian hamsters. Brain Res 2009; 1292:38-51. [PMID: 19643091 PMCID: PMC3995981 DOI: 10.1016/j.brainres.2009.07.062] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 06/13/2009] [Accepted: 07/17/2009] [Indexed: 11/18/2022]
Abstract
Neonatal monosodium glutamate (MSG) administration increases adiposity, decreases energy expenditure and is associated with arcuate nucleus (Arc) destruction. Disrupted brown adipose tissue (BAT) thermogenesis underlies some of these effects, although, interscapular BAT temperature (T(IBAT)) has not been measured. Therefore, we tested the effects of neonatal MSG or vehicle administration in Siberian hamsters and, when they were adults, measured T(IBAT) during acute cold exposure. The Arc and its projection to the hypothalamic paraventricular nucleus (PVH) are both components of the CNS outflow circuits to IBAT, with the latter implicated in BAT thermogenesis that could be compromised by MSG treatment. Using a viral transneuronal tract tracer, pseudorabies virus (PRV), we also tested whether the components of these circuits were intact. As adults, MSG-treated hamsters had significantly increased body mass and some white fat pad masses, markedly reduced Arc Nissl and neuropeptide staining, and PVH neuropeptide fiber staining. Cold-exposed (18 h at 5 degrees C) MSG- and vehicle-treated hamsters initially maintained T(IBAT), but the ability of the former waned after 2 h being significantly decreased by 18 h. PRV immunoreactive fibers/cells were not altered by neonatal MSG treatment despite substantial Arc and PVH destruction. MSG- and vehicle-treated hamsters given an exogenous norepinephrine challenge showed identical increases in the duration and peak of T(IBAT). Thus, the inability of MSG-treated animals to sustain T(IBAT) in the cold is not due to any obvious MSG-induced deletions of central sympathetic outflow circuits to IBAT, but appears to be extrinsic to the tissue nevertheless.
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Affiliation(s)
- Claudia Leitner
- Department of Biology, Neurobiology and Behavior and Brains and Behavior Programs, Georgia State University, 24 Peachtree Ctr Ave NE, Atlanta, GA 30302-4010, USA
| | - Timothy J. Bartness
- Department of Biology, Neurobiology and Behavior and Brains and Behavior Programs, Georgia State University, 24 Peachtree Ctr Ave NE, Atlanta, GA 30302-4010, USA
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Alarcon-Aguilar FJ, Almanza-Perez J, Blancas G, Angeles S, Garcia-Macedo R, Roman R, Cruz M. Glycine regulates the production of pro-inflammatory cytokines in lean and monosodium glutamate-obese mice. Eur J Pharmacol 2008; 599:152-8. [PMID: 18930730 DOI: 10.1016/j.ejphar.2008.09.047] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 09/10/2008] [Accepted: 09/25/2008] [Indexed: 12/22/2022]
Abstract
Fat tissue plays an important role in the regulation of inflammatory processes. Increased visceral fat has been associated with a higher production of cytokines that triggers a low-grade inflammatory response, which eventually may contribute to the development of insulin resistance. In the present study, we investigated whether glycine, an amino acid that represses the expression in vitro of pro-inflammatory cytokines in Kupffer and 3T3-L1 cells, can affect in vivo cytokine production in lean and monosodium glutamate-induced obese mice (MSG/Ob mice). Our data demonstrate that glycine treatment in lean mice suppressed TNF-alpha transcriptional expression in fat tissue, and serum protein levels of IL-6 were suppressed, while adiponectin levels were increased. In MSG/Ob mice, glycine suppressed TNF-alpha and IL-6 gene expression in fat tissue and significantly reduced protein levels of IL-6, resistin and leptin. To determine the role of peroxisome proliferator-activated receptor-gamma (PPAR-gamma) in the modulation of this inflammatory response evoked by glycine, we examined its expression levels in fat tissue. Glycine clearly increased PPAR-gamma expression in lean mice but not in MSG/Ob mice. Finally, to identify alterations in glucose metabolism by glycine, we also examined insulin levels and other biochemical parameters during an oral glucose tolerance test. Glycine significantly reduced glucose tolerance and raised insulin levels in lean but not in obese mice. In conclusion, our findings suggest that glycine suppresses the pro-inflammatory cytokines production and increases adiponectin secretion in vivo through the activation of PPAR-gamma. Glycine might prevent insulin resistance and associated inflammatory diseases.
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Affiliation(s)
- F J Alarcon-Aguilar
- Laboratorio de Farmacologia, Departamento de Ciencias de la Salud, Div. de Ciencias Biologicas y de la Salud, Universidad Autonoma Metropolitana Unidad Iztapalapa, Mexico, D.F. Mexico.
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Keen-Rhinehart E, Bartness TJ. Leptin inhibits food-deprivation-induced increases in food intake and food hoarding. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1737-46. [PMID: 18832088 DOI: 10.1152/ajpregu.90512.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Food deprivation stimulates foraging and hoarding and to a much lesser extent, food intake in Siberian hamsters. Leptin, the anorexigenic hormone secreted primarily from adipocytes, may act in the periphery, the brain, or both to inhibit these ingestive behaviors. Therefore, we tested whether leptin given either intracerebroventricularly or intraperitoneally, would block food deprivation-induced increases in food hoarding, foraging, and intake in animals with differing foraging requirements. Hamsters were trained in a running wheel-based food delivery foraging system coupled with simulated burrow housing. We determined the effects of food deprivation and several peripheral doses of leptin on plasma leptin concentrations. Hamsters were then food deprived for 48 h and given leptin (0, 10, 40, or 80 microg ip), and additional hamsters were food deprived for 48 h and given leptin (0, 1.25, 2.5, or 5.0 microg icv). Foraging, food intake, and hoarding were measured postinjection. Food deprivation stimulated food hoarding to a greater degree and duration than food intake. In animals with a foraging requirement, intracerebroventricular leptin almost completely blocked food deprivation-induced increased food hoarding and intake, but increased foraging. Peripheral leptin treatment was most effective in a sedentary control group, completely inhibiting food deprivation-induced increased food hoarding and intake at the two highest doses, and did not affect foraging at any dose. Thus, the ability of leptin to inhibit food deprivation-induced increases in ingestive behaviors differs based on foraging effort (energy expenditure) and the route of administration of leptin administration.
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Affiliation(s)
- Erin Keen-Rhinehart
- Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA
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