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Samad N, Manzoor N, Batool A, Noor A, Khaliq S, Aurangzeb S, Bhatti SA, Imran I. Protective effects of niacin following high fat rich diet: an in-vivo and in-silico study. Sci Rep 2023; 13:21343. [PMID: 38049514 PMCID: PMC10696033 DOI: 10.1038/s41598-023-48566-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 11/28/2023] [Indexed: 12/06/2023] Open
Abstract
Niacin had long been understood as an antioxidant. There were reports that high fat diet (HFD) may cause psychological and physical impairments. The present study was aimed to experience the effect of Niacin on % growth rate, cumulative food intake, motor activity and anxiety profile, redox status, 5-HT metabolism and brain histopathology in rats. Rats were administered with Niacin at a dose of 50 mg/ml/kg body weight for 4 weeks following normal diet (ND) and HFD. Behavioral tests were performed after 4 weeks. Animals were sacrificed to collect brain samples. Biochemical, neurochemical and histopathological studies were performed. HFD increased food intake and body weight. The exploratory activity was reduced and anxiety like behavior was observed in HFD treated animals. Activity of antioxidant enzymes was decreased while oxidative stress marker and serotonin metabolism in the brain of rat were increased in HFD treated animals than ND fed rats. Morphology of the brain was also altered by HFD administration. Conversely, Niacin treated animals decreased food intake and % growth rate, increased exploratory activity, produced anxiolytic effects, decreased oxidative stress and increased antioxidant enzyme and 5-HT levels following HFD. Morphology of brain is also normalized by the treatment of Niacin following HFD. In-silico studies showed that Niacin has a potential binding affinity with degradative enzyme of 5-HT i.e. monoamine oxidase (MAO) A and B with an energy of ~ - 4.5 and - 5.0 kcal/mol respectively. In conclusion, the present study showed that Niacin enhanced motor activity, produced anxiolytic effect, and reduced oxidative stress, appetite, growth rate, increased antioxidant enzymes and normalized serotonin system and brain morphology following HFD intake. In-silico studies suggested that increase 5-HT was associated with the binding of MAO with Niacin subsequentially an inhibition of the degradation of monoamine. It is suggested that Niacin has a great antioxidant potential and could be a good therapy for the treatment of HFD induced obesity.
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Affiliation(s)
- Noreen Samad
- Department of Biochemistry, Faculty of Science, Bahauddin Zakariya University, Multan, 60800, Pakistan.
| | - Natasha Manzoor
- Department of Biochemistry, Faculty of Science, Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Ammara Batool
- Department of Biochemistry, Faculty of Science, Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Aqsa Noor
- Department of Biochemistry, Faculty of Science, Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Saima Khaliq
- Department of Biochemistry, Faculty of Science, Science and Technology, Federal Urdu University of Arts, Karachi, 75270, Pakistan
| | - Sana Aurangzeb
- Department of Biochemistry, Faculty of Science, University of Karachi, Karachi, 75270, Pakistan
| | - Sheraz Ahmed Bhatti
- Department of Pathobiology, Faculty of Veterinary Science, Bahauddin Zakariya University, Multan, 60800, Pakistan
| | - Imran Imran
- Department of Pharmacology, Faculty of Pharmacy, Bahauddin Zakariya University, Multan, 60800, Pakistan
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Martin CT, Primeaux SD. The hypothalamic neuropeptide, QRFP, regulates high fat diet intake in female Long-Evans rats following ovariectomy. Peptides 2023; 162:170960. [PMID: 36690209 PMCID: PMC9992330 DOI: 10.1016/j.peptides.2023.170960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 12/12/2022] [Accepted: 01/20/2023] [Indexed: 01/22/2023]
Abstract
Obesity rates in women continue to increase throughout the lifespan and obesity-related comorbidities are prevalent in women in estrogen deficiency. The hypothalamic neuropeptide, QRFP, is an orexigenic peptide that increases the intake of high fat diet (HFD) in female rats and is overexpressed following ovariectomy (OVX). Therefore, the goal of the current series of experiments was to elucidate the effect of QRFP on HFD intake following OVX and determine if QRFP-26 administration in ovariectomized females altered expression of prepro-neuropeptide Y (NPY), agouti-related peptide (AgRP) and proopiomelanocortin (POMC) mRNA in the mediobasal hypothalamus (MBH) and prepro-orexin in the lateral hypothalamus (LH). The intake of HFD was measured following acute administration of QRFP-26 prior to or following estradiol benzoate (EB) treatment in ovariectomized females. When administered prior to EB treatment, QRFP-26 increased HFD intake. EB treatment attenuated the effects of QRFP-26 on HFD intake. Sub-chronic, continuous administration of QRFP-26 increased HFD intake and weight gain following OVX. Subchronic, continuous administration of QRFP siRNA into the 3rd ventricle via osmotic pump decreased prepro-QRFP mRNA levels in the MBH by ∼75%, decreased HFD intake and decreased weight gain following OVX. QRFP-26administration did not alter the expression of prepro-NPY, AgRP or POMC mRNA in the MBH, but decreased prepro-orexin mRNA in the LH of ovariectomized females. Overall, results from these studies support the orexigenic neuropeptide, QRFP, as an important mediator of the ingestion of highly palatable foods and subsequent weight gain in females during estrogen deficiency.
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Affiliation(s)
- Cade T Martin
- Department of Physiology, LSU Health Sciences Center-NO, New Orleans, LA 70112, USA
| | - Stefany D Primeaux
- Department of Physiology, LSU Health Sciences Center-NO, New Orleans, LA 70112, USA; Joint Diabetes, Endocrinology & Metabolism Program, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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3
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Jing M, Wang S, Li D, Wang Z, Li Z, Lu Y, Sun T, Qiu C, Chen F, Yu H, Zhang W. Lorcaserin Inhibit Glucose-Stimulated Insulin Secretion and Calcium Influx in Murine Pancreatic Islets. Front Pharmacol 2021; 12:761966. [PMID: 34803706 PMCID: PMC8602196 DOI: 10.3389/fphar.2021.761966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 09/27/2021] [Indexed: 11/13/2022] Open
Abstract
Lorcaserin is a serotonergic agonist specific to the 5-hydroxytryptamine 2c receptor (5-HT2CR) that is FDA approved for the long-term management of obesity with or without at least one weight-related comorbidity. Lorcaserin can restrain patients' appetite and improve insulin sensitivity and hyperinsulinemia mainly through activating 5-HT2CR in the hypothalamus. It is known that the mCPP, a kind of 5-HT2CR agonist, decreases plasma insulin concentration in mice and previous research in our laboratory found that mCPP inhibited glucose-stimulated insulin secretion (GSIS) by activating 5-HT2CR on the β cells. However, the effect of lorcaserin on GSIS of pancreatic β cell has not been studied so far. The present study found that 5-HT2CR was expressed in both mouse pancreatic β cells and β-cell-derived MIN6 cells. Dose-dependent activation of 5-HT2CR by lorcaserin suppressed GSIS and SB242084 or knockdown of 5-HT2CR abolished lorcaserin's effect in vitro. Additionally, lorcaserin also suppressed GSIS in high-fat diet (HFD)-fed mice in dose-dependent manner. Lorcaserin did not change insulin synthesis ATP content, but lorcaserin decrease cytosolic free calcium level [(Ca2+)i] in MIN6 cells stimulated with glucose and also inhibit insulin secretion and (Ca2+)i in MIN6 treated with potassium chloride. Furthermore, stimulation with the L-type channel agonist, Bay K8644 did not restore GSIS in MIN6 exposed to lorcaserin. Lorcaserin inhibits the cAMP generation of MIN6 cells and pretreatment with the Gα i/o inhibitor pertussis toxin (PTX), abolished lorcaserin-induced suppression of GSIS in β cells, while membrane-permeable cAMP analogue db-cAMP had same effect as PTX. These date indicated lorcaserin coupled to PTX-sensitive Gα i/o proteins in β cells reduced intracellular cAMP level and Ca2+ influx, thereby causing GSIS dysfunction of β cell. These results highlight a novel signaling mechanism of lorcaserin and provide valuable insights into the further investigation of 5-HT2CR functions in β-cell biology and it also provides guidance for the clinical application of lorcaserin.
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Affiliation(s)
- Muhan Jing
- School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Shanshan Wang
- Laboratory Animal Center, Department of Science and Technology, Nanjing University of Chinese Medicine, Nanjing, China
| | - Ding Li
- Department of Forensic Medicine, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Zeyu Wang
- School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Ziwen Li
- School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Yichen Lu
- School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Tong Sun
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China.,Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Chen Qiu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China
| | - Fang Chen
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China.,Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
| | - Haijuan Yu
- Department of Obstetrics, Traditional Chinese Medicine Hospital of Jingning, Nanjing, China
| | - Wei Zhang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, China.,Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China
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Schreiber A, Braymer HD, Primeaux SD. Transection of Gustatory Nerves Differentially Affects Dietary Fat Intake in Obesity-Prone and Obesity-Resistant Rats. Chem Senses 2021; 45:541-548. [PMID: 32766712 DOI: 10.1093/chemse/bjaa053] [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: 01/08/2023] Open
Abstract
The current prevalence of obesity has been linked to the consumption of highly palatable foods and may be mediated by a dysregulated or hyposensitive orosensory perception of dietary fat, thereby contributing to the susceptibility to develop obesity. The goal of the current study was to investigate the role of lingual taste input in obesity-prone (OP, Osborne-Mendel) and obesity-resistant (OR, S5B/Pl) rats on the consumption of a high-fat diet (HFD). Density of fungiform papillae was assessed as a marker of general orosensory input. To determine if orosensory afferent input mediates dietary fat intake, surgical transection of the chorda tympani and glossopharyngeal nerves (GLX/CTX) was performed in OP and OR rats and HFD caloric intake and body weight were measured. Fungiform papillae density was lower in OP rats, compared with OR rats. GLX/CTX decreased orosensory input in both OP and OR rats, as measured by an increase in the intake of a bitter, quinine solution. Consumption of low-fat diet was not altered by GLX/CTX in OP and OR rats; however, GLX/CTX decreased HFD intake in OR, without altering HFD intake in OP rats. Overall, these data suggest that inhibition of orosensory input in OP rats do not decrease fat intake, thereby supporting that idea that hyposensitive and/or dysregulated orosensory perception of highly palatable foods contribute to the susceptibility to develop obesity.
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Affiliation(s)
- Allyson Schreiber
- Department of Physiology, LSU Health Sciences Center, New Orleans, LA, USA
| | - Hugh Douglas Braymer
- Joint Diabetes, Endocrinology & Metabolism Program, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Stefany D Primeaux
- Department of Physiology, LSU Health Sciences Center, New Orleans, LA, USA.,Joint Diabetes, Endocrinology & Metabolism Program, Pennington Biomedical Research Center, Baton Rouge, LA, USA
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Michaelides M, Miller ML, Egervari G, Primeaux SD, Gomez JL, Ellis RJ, Landry JA, Szutorisz H, Hoffman AF, Lupica CR, Loos RJF, Thanos PK, Bray GA, Neumaier JF, Zachariou V, Wang GJ, Volkow ND, Hurd YL. Striatal Rgs4 regulates feeding and susceptibility to diet-induced obesity. Mol Psychiatry 2020; 25:2058-2069. [PMID: 29955167 PMCID: PMC6310669 DOI: 10.1038/s41380-018-0120-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 05/10/2018] [Accepted: 05/14/2018] [Indexed: 12/16/2022]
Abstract
Consumption of high fat, high sugar (western) diets is a major contributor to the current high levels of obesity. Here, we used a multidisciplinary approach to gain insight into the molecular mechanisms underlying susceptibility to diet-induced obesity (DIO). Using positron emission tomography (PET), we identified the dorsal striatum as the brain area most altered in DIO-susceptible rats and molecular studies within this region highlighted regulator of G-protein signaling 4 (Rgs4) within laser-capture micro-dissected striatonigral (SN) and striatopallidal (SP) medium spiny neurons (MSNs) as playing a key role. Rgs4 is a GTPase accelerating enzyme implicated in plasticity mechanisms of SP MSNs, which are known to regulate feeding and disturbances of which are associated with obesity. Compared to DIO-resistant rats, DIO-susceptible rats exhibited increased striatal Rgs4 with mRNA expression levels enriched in SP MSNs. siRNA-mediated knockdown of striatal Rgs4 in DIO-susceptible rats decreased food intake to levels comparable to DIO-resistant animals. Finally, we demonstrated that the human Rgs4 gene locus is associated with increased body weight and obesity susceptibility phenotypes, and that overweight humans exhibit increased striatal Rgs4 protein. Our findings highlight a novel role for involvement of Rgs4 in SP MSNs in feeding and DIO-susceptibility.
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Affiliation(s)
- Michael Michaelides
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Biobehavioral Imaging & Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
- Department of Psychiatry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
- Biobehavioral Imaging & Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Michael L Miller
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Gabor Egervari
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Stefany D Primeaux
- Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - Juan L Gomez
- Biobehavioral Imaging & Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Randall J Ellis
- Biobehavioral Imaging & Molecular Neuropsychopharmacology Unit, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Joseph A Landry
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Henrietta Szutorisz
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Carl R Lupica
- Electrophysiology Research Section, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, 21224, USA
| | - Ruth J F Loos
- The Charles Bronfman Institute for Personalized Medicine, The Mindich Child Health and Development Institute, The Genetics of Obesity and Related Metabolic Traits Program, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Panayotis K Thanos
- Research Institute on Addictions, University at Buffalo, Buffalo, NY, 14203, USA
| | - George A Bray
- Pennington Biomedical Research Center, Baton Rouge, LA, 70808, USA
| | - John F Neumaier
- Departments of Psychiatry and Pharmacology, University of Washington, Seattle, WA, 98195, USA
| | - Venetia Zachariou
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Gene-Jack Wang
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nora D Volkow
- Laboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yasmin L Hurd
- Departments of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
- Departments of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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Kesić M, Baković P, Horvatiček M, Proust BLJ, Štefulj J, Čičin-Šain L. Constitutionally High Serotonin Tone Favors Obesity: Study on Rat Sublines With Altered Serotonin Homeostasis. Front Neurosci 2020; 14:219. [PMID: 32269507 PMCID: PMC7109468 DOI: 10.3389/fnins.2020.00219] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/27/2020] [Indexed: 01/08/2023] Open
Abstract
Central and peripheral pools of biogenic monoamine serotonin (5-hydroxytryptamine [5HT]) exert opposite effects on the body weight regulation: increase in brain 5HT activity is expected to decrease body weight, whereas increase in peripheral 5HT activity will increase body weight and adiposity. In a genetic model of rats with constitutionally high- or low-5HT homeostasis (hyperserotonergic/hyposerotonergic rats), we have studied how individual differences in endogenous 5HT tone modulate net energy balance of the organism. The high-5HT and low-5HT sublines of the model were developed by selective breeding toward extreme platelet activities of 5HT transporter, a key molecule determining 5HT bioavailability/activity. In animals from high-5HT and low-5HT sublines, we assessed physiological characteristics associated with body weight homeostasis and expression profile of a large scale of body weight–regulating genes in hypothalamus, a major brain region controlling energy balance. Results showed that under standard chow diet animals from the high-5HT subline, as compared to low-5HT animals, have lifelong increased body weight (by 12%), higher absolute daily food intake (by 9%), and different pattern of fat distribution (larger amount of white adipose tissue and lower amount of brown adipose tissue). A large number of body weight–regulating hypothalamic genes were analyzed for their mRNA expression: 24 genes by reverse transcription–quantitative polymerase chain reaction (n = 9–10 rats/subline) including neuropeptides and their receptors, growth factors, transcriptional factors, and receptors for peripheral signals, and a total of 84 genes of various classes by polymerase chain reaction array (pools of six rats/subline). Only few genes showed significant differences in mRNA expression levels between 5HT sublines (e.g. neuropeptide Y receptor, fibroblast growth factor 10), but high-5HT animals displayed a clear trend to upregulation of mRNAs for a number of orexigenic signaling peptides, their receptors, and other molecules with orexigenic activity. Receptors for peripheral signals (leptin, insulin) and molecules in their downstream signaling were not altered, indicating no changes in central insulin/leptin resistance. At the protein level, there were no differences in the content of hypothalamic leptin receptor between 5HT sublines, but significant sex and age effects were observed. Results show that higher constitutive/individual 5HT tone favors higher body weight and adiposity probably due to concurrent upregulation of several hypothalamic orexigenic pathways.
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Affiliation(s)
- Maja Kesić
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Petra Baković
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Marina Horvatiček
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Bastien Lucien Jean Proust
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Jasminka Štefulj
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Lipa Čičin-Šain
- Laboratory of Neurochemistry and Molecular Neurobiology, Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
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The dorsomedial hypothalamus and nucleus of the solitary tract as key regulators in a rat model of chronic obesity. Brain Res 2020; 1727:146538. [DOI: 10.1016/j.brainres.2019.146538] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 10/07/2019] [Accepted: 10/29/2019] [Indexed: 01/29/2023]
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Sirohi S, Skripnikova E, Davis JF. Vertical Sleeve Gastrectomy Attenuates Hedonic Feeding Without Impacting Alcohol Drinking in Rats. Obesity (Silver Spring) 2019; 27:603-611. [PMID: 30740914 PMCID: PMC6430654 DOI: 10.1002/oby.22415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 11/13/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Roux-en-Y gastric bypass surgery and vertical sleeve gastrectomy (VSG) are the most commonly performed bariatric procedures. Whereas studies report new-onset alcohol misuse following Roux-en-Y gastric bypass, the impact of VSG on alcohol intake is less clear. Hedonic feeding, alcohol drinking, and hypothalamic obesity-related gene expression following VSG were evaluated. METHODS Male Long-Evans rats underwent VSG or sham surgery. To evaluate hedonic feeding, rats received a high-fat diet following behavioral satiation on chow. Alcohol (5%-10% v/v) drinking was assessed in a two-bottle choice paradigm. Finally, polymerase chain reaction array evaluated gene expression. RESULTS VSG induced moderate but significant weight loss. Sham rats significantly escalated high-fat diet intake following behavioral satiation, an effect significantly reduced in VSG rats. A moderate decrease in alcohol intake was observed in VSG rats at low (5%) alcohol concentration. However, overall, no significant between-group differences were evident. Key hypothalamic orexigenic transcripts linked to stimulation of food and alcohol intake were significantly decreased in VSG rats. CONCLUSIONS VSG attenuated hedonic feeding without impacting alcohol drinking, an effect potentially mediated by alterations in genetic information flow within the hypothalamus. Importantly, these data highlight VSG as an effective bariatric procedure with a potentially reduced risk of developing alcohol use disorder.
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Affiliation(s)
- Sunil Sirohi
- Laboratory of Endocrine and Neuropsychiatric Disorders, Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA
- Corresponding Authors: Jon F. Davis, PhD, Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, 1815 Ferdinand’s Lane, Pullman, WA, 99164, Tel (Office): 509-335-8163, , Sunil Sirohi, PhD, Laboratory of Endocrine and Neuropsychiatric Disorders, Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, 1 Drexel Dr., New Orleans, LA 70125, Tel (Office): 504-520-5471; (lab) 504-520-5332, ;
| | - Elena Skripnikova
- Laboratory of Endocrine and Neuropsychiatric Disorders, Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, New Orleans, LA
| | - Jon F. Davis
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
- Corresponding Authors: Jon F. Davis, PhD, Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, 1815 Ferdinand’s Lane, Pullman, WA, 99164, Tel (Office): 509-335-8163, , Sunil Sirohi, PhD, Laboratory of Endocrine and Neuropsychiatric Disorders, Division of Basic Pharmaceutical Sciences, College of Pharmacy, Xavier University of Louisiana, 1 Drexel Dr., New Orleans, LA 70125, Tel (Office): 504-520-5471; (lab) 504-520-5332, ;
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Douglas Braymer H, Zachary H, Schreiber AL, Primeaux SD. Lingual CD36 and nutritional status differentially regulate fat preference in obesity-prone and obesity-resistant rats. Physiol Behav 2017; 174:120-127. [PMID: 28302572 DOI: 10.1016/j.physbeh.2017.03.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/20/2017] [Accepted: 03/11/2017] [Indexed: 11/16/2022]
Abstract
Lingual fatty acid receptors (i.e. CD36) mediate the orosensory perception of fat/fatty acids and may contribute to the susceptibility to develop obesity. The current study tested the hypothesis that fat/fatty acid preference in obesity-prone (OP, Osborne-Mendel) and obesity-resistant (OR, S5B/Pl) rats is mediated by nutritional status and lingual CD36. To determine if nutritional status affected linoleic acid (LA) preference in OP and OR rats, rats were either fasted overnight or fed a high fat diet (60% kcal from fat). In OR rats, fasting increased the preference for higher concentrations of LA (1.0%), while consumption of a high fat diet decreased LA preference. In OP rats, fasting increased the preference for lower concentrations of LA (0.25%), however high fat diet consumption did not alter LA preference. To determine if lingual CD36 mediated the effects of an overnight fast on LA preference, the expression of lingual CD36 mRNA was assessed and the effect of lingual application of CD36 siRNA on LA preference was determined. Fasting increased lingual CD36 mRNA expression in OR rats, but failed to alter lingual CD36 mRNA in OP rats. Following an overnight fast, application of lingual CD36 siRNA led to a decrease in LA preference in OR, but not OP rats. Lingual application of CD36 siRNA was also used to determine if lingual CD36 mediated the intake and preference for a high fat diet in OP and OR rats. CD36 siRNA decreased the preference and intake of high fat diet in OR rats, but not OP rats. The results from this study suggest that the dysregulation of lingual CD36 in OP rats is a potential factor leading to increased fat intake and fat preference and an enhanced susceptibility to develop obesity.
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Affiliation(s)
- H Douglas Braymer
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, United States
| | - Hannah Zachary
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, United States
| | - Allyson L Schreiber
- Department of Physiology, LSU Health Sciences Center, New Orleans, LA 70112, United States
| | - Stefany D Primeaux
- Department of Physiology, LSU Health Sciences Center, New Orleans, LA 70112, United States; Joint Diabetes, Endocrinology & Metabolism Program, Pennington Biomedical Research Center, Baton Rouge, LA 70808, United States.
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10
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Martins IJ. Magnesium Therapy Prevents Senescence with the Reversal of Diabetes and Alzheimer’s Disease. Health (London) 2016. [DOI: 10.4236/health.2016.87073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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van den Heuvel JK, Eggels L, van Rozen AJ, Luijendijk MCM, Fliers E, Kalsbeek A, Adan RAH, la Fleur SE. Neuropeptide Y and leptin sensitivity is dependent on diet composition. J Neuroendocrinol 2014; 26:377-85. [PMID: 24698502 DOI: 10.1111/jne.12155] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 03/26/2014] [Accepted: 03/28/2014] [Indexed: 11/28/2022]
Abstract
Rats on different free-choice (fc) diets for 1 week of either chow, saturated fat and liquid sugar (fcHFHS), chow and saturated fat (fcHF), or chow and liquid sugar (fcHS) have differential levels of neuropeptide Y (NPY) mRNA in the arcuate nucleus. Because these differences were not explained by plasma leptin levels but did predict subsequent feeding behaviour, in the present study, we first examined whether leptin sensitivity could explain these differences. Second, we focused on the role of NPY on feeding behaviour, and measured NPY mRNA levels and sensitivity to NPY after 4 weeks on the different choice diets. To determine leptin sensitivity, we measured food intake after i.p. leptin or vehicle injections in male Wistar rats subjected to the fcHFHS, fcHS, fcHF or Chow diets for 7 days. Next, we measured levels of arcuate nucleus NPY mRNA with in situ hybridisation in rats subjected to the choice diets for 4 weeks. Finally, we studied NPY sensitivity in rats subjected to the fcHFHS, fcHS, fcHF or Chow diet for 4 weeks by measuring food intake after administration of NPY or vehicle in the lateral ventricle. Leptin decreased caloric intake in rats on Chow, fcHS and fcHF but not in rats on the fcHFHS diet. After 4 weeks, rats on the fcHFHS diet remained hyperphagic, whereas fcHS and fcHF rats decreased caloric intake to levels similar to rats on Chow. By contrast to 1 week, after 4 weeks, levels of NPY mRNA were not different between the diet groups. Lateral ventricle administration of NPY resulted in higher caloric intake in fcHFHS rats compared to rats on the other choice diets or rats on Chow. Our data show that consuming a combination of saturated fat and liquid sugar results in leptin resistance and increased NPY sensitivity that is associated with persistent hyperphagia.
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Affiliation(s)
- J K van den Heuvel
- Department of Endocrinology and Metabolism, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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Martins IJ. Induction of NAFLD with Increased Risk of Obesity and Chronic Diseases in Developed Countries. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojemd.2014.44011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Chen CSY, Bench EM, Allerton TD, Schreiber AL, Arceneaux KP, Primeaux SD. Preference for linoleic acid in obesity-prone and obesity-resistant rats is attenuated by the reduction of CD36 on the tongue. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1346-55. [PMID: 24154509 PMCID: PMC3882564 DOI: 10.1152/ajpregu.00582.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 10/18/2013] [Indexed: 11/22/2022]
Abstract
Differential sensing of dietary fat and fatty acids by the oral cavity is proposed to regulate the susceptibility to obesity. In the current experiments, animals that differ in their susceptibility to obesity were used to investigate the influence of the oral cavity on the preference for the polyunsaturated fatty acid, linoleic acid. In experiment 1, the preference for differing concentrations of linoleic acid was determined in obesity-prone Osborne-Mendel (OM) and obesity-resistant S5B/Pl (S5B) rats. The preference threshold for linoleic acid was lower in S5B rats, compared with OM rats. To determine whether differences in linoleic acid preference threshold were related to innate strain differences in the fatty acid receptors on the tongue, the expression of GPR120, GPR40, and CD36 on the circumvallate papillae were assessed in OM and S5B rats. Results indicated that the expression of CD36, GPR40, and GPR120 did not differ between these two strains. Numerous studies have examined the role of CD36 on fat intake; therefore, in experiment 3, RNA interference was used to decrease the expression of CD36 on the tongues of OM and S5B rats, and the effect of decreased CD36 expression on linoleic acid preference was determined. CD36 siRNA attenuated linoleic acid preference for the most preferred concentration in both OM and S5B rats. Overall, these data indicate that there are innate differences in the preference threshold for linoleic acid in obesity-prone and obesity-resistant rats. Experimentally reducing the expression of CD36 on the circumvallate papillae attenuated the preference for linoleic acid in both strains.
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Affiliation(s)
- Christina S-Y Chen
- Joint Diabetes, Endocrinology and Metabolism Program, Louisiana State University System, Louisiana State University Health Science Center-New Orleans, New Orleans, Lousiana; and
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Li JX, Ju S, Baladi MG, Koek W, France CP. Eating high fat chow increases the sensitivity of rats to 8-OH-DPAT-induced lower lip retraction. Behav Pharmacol 2013; 22:751-7. [PMID: 21979831 DOI: 10.1097/fbp.0b013e32834d0eeb] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eating high fat food can alter sensitivity to drugs acting on dopamine systems; this study examined whether eating high fat food alters sensitivity to a drug acting on serotonin (5-HT) systems. Sensitivity to (+)-8-hydroxy-2-(dipropylamino) tetralin hydrobromide (8-OH-DPAT; 5-HT1A receptor agonist)-induced lower lip retraction was examined in separate groups (n=8-9) of rats with free access to standard (5.7% fat) or high fat (34.3% fat) chow; sensitivity to quinpirole (dopamine D3/D2 receptor agonist)-induced yawning was also examined. Rats eating high fat chow gained more body weight than rats eating standard chow and, after 6 weeks of eating high fat chow, they were more sensitive to 8-OH-DPAT (0.01-0.1 mg/kg)-induced lower lip retraction and quinpirole (0.0032-0.32 mg/kg)-induced yawning. These changes were not reversed when rats that previously ate high fat chow were switched to eating standard chow and sensitivity to 8-OH-DPAT and quinpirole increased when rats that previously ate standard chow ate high fat chow. These data extend previous results showing changes in sensitivity to drugs acting on dopamine systems in animals eating high fat chow to a drug acting at 5-HT1A receptors and they provide support for the notion that eating certain foods impacts sensitivity to drugs acting on monoamine systems.
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Affiliation(s)
- Jun-Xu Li
- Department of Pharmacology, University of Texas Health Science Center, San Antonio, Texas 78229 3900, USA
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Primeaux SD, Braymer HD, Bray GA. CD36 mRNA in the gastrointestinal tract is differentially regulated by dietary fat intake in obesity-prone and obesity-resistant rats. Dig Dis Sci 2013; 58:363-70. [PMID: 22915197 PMCID: PMC4201504 DOI: 10.1007/s10620-012-2364-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 08/06/2012] [Indexed: 01/16/2023]
Abstract
BACKGROUND The gastrointestinal tract (GI) is important for detection and transport of consumed nutrients and has been implicated in susceptibility to diet-induced obesity in various rat strains. AIMS The current studies investigated the regulation of CD36, a receptor which facilitates uptake of long-chain fatty acids, in the GI tract of obesity-prone Osborne-Mendel and obesity-resistant S5B rats fed a high-fat diet. METHODS Osborne-Mendel and S5B rats consumed a high-fat diet (HFD, 55 % kcal from fat) or a low-fat diet (10 % kcal from fat) for either 3 or 14 days. CD36 messenger RNA (mRNA) levels were measured from circumvallate papillae of the tongue and from duodenal enterocytes. RESULTS In Osborne-Mendel rats, consumption of HFD for 3 and 14 days led to an increase in CD36 mRNA on circumvallate papillae and in duodenal enterocytes. CD36 mRNA levels were positively correlated with body weight gain and kilocalories consumed at 3 days. In S5B rats, consumption of HFD for 3 days did not alter CD36 mRNA levels on circumvallate papillae or in the duodenum. Duodenal CD36 levels were elevated in S5B rats following 14 days of HFD consumption. CD36 mRNA levels in the duodenum were positively correlated with body weight gain and kilocalories consumed at 14 days. CONCLUSIONS These data support the differential sensing of nutrients by two regions of the GI tract of obesity-prone and obesity-resistant rats consuming HFD and suggest a role for CD36 in the strain-specific susceptibility to obesity.
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Affiliation(s)
- Stefany D. Primeaux
- Joint Diabetes, Endocrinology and Metabolism Program, Louisiana State University System, Louisiana State University Health Science Center-New Orleans, New Orleans, LA 70112, USA. Internal Medicine-Endocrinology, Diabetes & Metabolism, LSUHSC-NO, 1542 Tulane Ave, Box T4 M-2, New Orleans, LA 70112, USA
| | | | - George A. Bray
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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Gene expression changes in the septum: possible implications for microRNAs in sculpting the maternal brain. PLoS One 2012; 7:e38602. [PMID: 22701680 PMCID: PMC3368935 DOI: 10.1371/journal.pone.0038602] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Accepted: 05/12/2012] [Indexed: 01/08/2023] Open
Abstract
The transition from the non-maternal to the maternal state is characterized by a variety of CNS alterations that support the care of offspring. The septum (including lateral and medial portions) is a brain region previously linked to various emotional and motivational processes, including maternal care. In this study, we used microarrays (PLIER algorithm) to examine gene expression changes in the septum of postpartum mice and employed gene set enrichment analysis (GSEA) to identify possible regulators of altered gene expression. Genes of interest identified as differentially regulated with microarray analysis were validated with quantitative real-time PCR. We found that fatty acid binding protein 7 (Fabp7) and galanin (Gal) were downregulated, whereas insulin-like growth factor binding protein 3 (Igfbp3) was upregulated in postpartum mice compared to virgin females. These genes were previously found to be differentially regulated in other brain regions during lactation. We also identified altered expression of novel genes not previously linked to maternal behavior, but that could play a role in postpartum processes, including glutamate-ammonia ligase (Glul) and somatostatin receptor 1 (Sstr1) (both upregulated in postpartum). Genes implicated in metabolism, cell differentiation, or proliferation also exhibited altered expression. Unexpectedly, enrichment analysis revealed a high number of microRNAs, transcription factors, or conserved binding sites (177 with corrected P-value <0.05) that were significantly linked to maternal upregulated genes, while none were linked to downregulated genes. MicroRNAs have been linked to placenta and mammary gland development, but this is the first indication they may also play a key role in sculpting the maternal brain. Together, this study provides new insights into genes (along with possible mechanisms for their regulation) that are involved in septum-mediated adaptations during the postpartum period.
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Wallace TJ, Zai CC, Brandl EJ, Müller DJ. Role of 5-HT(2C) receptor gene variants in antipsychotic-induced weight gain. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2011; 4:83-93. [PMID: 23226055 PMCID: PMC3513221 DOI: 10.2147/pgpm.s11866] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Indexed: 12/29/2022]
Abstract
Antipsychotic-induced weight gain is a serious side effect of antipsychotic medication that can lead to increased morbidity, mortality, and non-compliance in patients. Numerous single nucleotide polymorphisms have been studied for association with antipsychotic-induced weight gain in an attempt to find genetic predictors of this side effect. An ability to predict this side effect could lead to personalized treatment plans for predisposed individuals, which could significantly decrease the prevalence and severity of weight gain. Variations in the serotonin receptor 2c gene (HTR2C) have emerged as promising candidates for prediction of antipsychotic-induced weight gain. Specifically, the well-studied −759C/T promoter polymorphism has been associated with weight gain in diverse populations, although some studies have reported no association. This discrepancy is likely due to heterogeneity in study design with respect to ethnicity, treatment duration, and other variables. Notably, the association between HTR2C and antipsychotic-induced weight gain appears strongest in short-term studies on patients with limited or no previous antipsychotic treatment. Other, less extensively studied promoter polymorphisms (−697C/G, −997G/A, and −1165A/G) have also emerged as potential predictors of antipsychotic-induced weight gain. Conversely, the well-studied intronic polymorphism Cys23Ser does not appear to be associated. With further research on both HTR2C and other genetic and environmental predictors of antipsychotic-induced weight gain, a predictive test could one day be created to screen patients and provide preventative or alternative treatment for those who are predisposed to this serious side effect.
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Affiliation(s)
- Tessa Jm Wallace
- Neurogenetics Section, Center for Addiction and Mental Health, Department of Psychiatry, University of Toronto, Toronto, ON, Canada
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Brown LM, Hansen CT, Huberty AF, Castonguay T. Traits of the metabolic syndrome alter corpulent obesity in LAN, SHR and DSS rats: Behavioral and metabolic interactions with adrenalectomy. Physiol Behav 2011; 103:98-103. [DOI: 10.1016/j.physbeh.2010.12.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 12/02/2010] [Accepted: 12/20/2010] [Indexed: 11/30/2022]
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Thanos PK, Kim R, Cho J, Michaelides M, Anderson BJ, Primeaux SD, Bray GA, Wang GJ, Robinson JK, Volkow ND. Obesity-resistant S5B rats showed greater cocaine conditioned place preference than the obesity-prone OM rats. Physiol Behav 2010; 101:713-8. [PMID: 20801137 PMCID: PMC3477469 DOI: 10.1016/j.physbeh.2010.08.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Revised: 08/13/2010] [Accepted: 08/16/2010] [Indexed: 11/20/2022]
Abstract
BACKGROUND Dopamine (DA) and the DA D2 receptor (D2R) are involved in the rewarding and conditioned responses to food and drug rewards. Osborne-Mendel (OM) rats are genetically prone and S5B/P rats are genetically resistant to obesity when fed a high-fat diet. We hypothesized that the differential sensitivity of these two rat strains to natural rewards may also be reflected in sensitivity to drugs of abuse. Therefore, we tested whether OM and S5B/P rats showed a differential preference to cocaine using conditioned place preference (CPP). To also evaluate whether there is specific involvement of the D2R in this differential conditioning sensitivity, we then tested whether the D2R agonist bromocriptine (BC) would differentially affect the effects of cocaine in the two strains. METHODS OM and S5B/P rats were conditioned with cocaine (5 or 10mg/kg) in one chamber and saline in another for 8days. Rats were then tested for cocaine preference. The effects of BC (0.5, 1, 5, 10, 20mg/kg) on cocaine preference were then assessed in subsequent test sessions. RESULTS OM rats did not show a significant preference for the cocaine-paired chamber on test day. Only the S5B/P rats showed cocaine CPP. Later treatment with only the highest dose of BC resulted in reduced cocaine CPP in S5B/P rats when treated with 5mg/kg cocaine and in OM rats treated with 10mg/kg cocaine. CONCLUSION Our results indicated that obesity-resistant S5B rats showed greater cocaine CPP than the obesity-prone OM rats. These findings do not support a theory of common vulnerability for reinforcer preferences (food and cocaine). However, they show that BC reduced cocaine conditioning effects supporting at least a partial regulatory role of D2R in conditioned responses to drugs.
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Affiliation(s)
- Panayotis K Thanos
- Laboratory of Neuroimaging, NIAAA, NIH, Department of Health and Human Services, Bethesda, MD, United States.
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York DA, Teng L, Park-York M. Effects of dietary fat and enterostatin on dopamine and 5-hydroxytrytamine release from rat striatal slices. Brain Res 2010; 1349:48-55. [PMID: 20599830 DOI: 10.1016/j.brainres.2010.06.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 06/10/2010] [Accepted: 06/15/2010] [Indexed: 01/19/2023]
Abstract
Studies have demonstrated defects of DA and 5HT neurotransmission in dietary fat induced obese animals. In the present study, we used a perfusion system to assay the release of DA and 5HT from striatal slices preloaded with [(3)H]-DA or [(3)H]-5HT. The release of both DA and 5HT from striatal slices of rats fed a high fat diet for 10 days, but not 3 days, was reduced when compared to striatal slices taken from rats fed a low fat diet. Enterostatin, an endogenous pentapeptide inhibits dietary fat intake when administered peripherally and centrally in animals. The central mechanism for the action of enterostatin is not yet determined even though several mechanisms have been suggested. We have shown that enterostatin enhanced [(3)H]-DA release, but not [(3)H]-5HT release from striatal slices of rats that had been adapted to high fat diet for 10 days. The enterostatin-induced increase in [(3)H]-DA release was blocked by nomifensine. Enterostatin did not alter [(3)H]-DA or [(3)H]-5HT release from striatal slices of rats adapted to high fat or low fat diet feeding for 3 days. These findings suggest that enterostatin may inhibit dietary fat intake by blocking dopamine reuptake transport to increase central striatal DA release from rats that have acquired diminished dopamine signal after an adaptive period of fat consumption.
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Affiliation(s)
- David A York
- Center for Advanced Nutrition and Department of Biology, Utah State University, 4715 Old Main Hill, Logan, UT 84322-4715, USA.
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Watanabe RLH, Andrade IS, Telles MM, Albuquerque KT, Nascimento CMO, Oyama LM, Casarini DE, Ribeiro EB. Long-term consumption of fish oil-enriched diet impairs serotonin hypophagia in rats. Cell Mol Neurobiol 2010; 30:1025-33. [PMID: 20526668 DOI: 10.1007/s10571-010-9533-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Accepted: 05/14/2010] [Indexed: 11/28/2022]
Abstract
Hypothalamic serotonin inhibits food intake and stimulates energy expenditure. High-fat feeding is obesogenic, but the role of polyunsaturated fats is not well understood. This study examined the influence of different high-PUFA diets on serotonin-induced hypophagia, hypothalamic serotonin turnover, and hypothalamic protein levels of serotonin transporter (ST), and SR-1B and SR-2C receptors. Male Wistar rats received for 9 weeks from weaning a diet high in either soy oil or fish oil or low fat (control diet). Throughout 9 weeks, daily intake of fat diets decreased such that energy intake was similar to that of the control diet. However, the fish group developed heavier retroperitoneal and epididymal fat depots. After 12 h of either 200 or 300 μg intracerebroventricular serotonin, food intake was significantly inhibited in control group (21-25%) and soy group (37-39%) but not in the fish group. Serotonin turnover was significantly lower in the fish group than in both the control group (-13%) and the soy group (-18%). SR-2C levels of fish group were lower than those of control group (50%, P = 0.02) and soy group (37%, P = 0.09). ST levels tended to decrease in the fish group in comparison to the control group (16%, P = 0.339) and the soy group (21%, P = 0.161). Thus, unlike the soy-oil diet, the fish-oil diet decreased hypothalamic serotonin turnover and SR-2C levels and abolished serotonin-induced hypophagia. Fish-diet rats were potentially hypophagic, suggesting that, at least up to this point in its course, the serotonergic impairment was either compensated by other factors or not of a sufficient extent to affect feeding. That fat pad weight increased in the absence of hyperphagia indicates that energy expenditure was affected by the serotonergic hypofunction.
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Affiliation(s)
- Regina L H Watanabe
- Departamento de Fisiologia, Universidade Federal de São Paulo, Rua Botucatu, São Paulo, SP, Brazil
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Vergara-Rodriguez P, Vibhakar S, Watts J. Metabolic syndrome and associated cardiovascular risk factors in the treatment of persons with human immunodeficiency virus and severe mental illness. Pharmacol Ther 2009; 124:269-78. [DOI: 10.1016/j.pharmthera.2009.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 07/10/2009] [Indexed: 01/02/2023]
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Drago A, Serretti A. Focus on HTR2C: A possible suggestion for genetic studies of complex disorders. Am J Med Genet B Neuropsychiatr Genet 2009; 150B:601-37. [PMID: 18802918 DOI: 10.1002/ajmg.b.30864] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
HTR2C is one of the most relevant and investigated serotonin receptors. Its role in important brain structures such as the midbrain, the lateral septal complex, the hypothalamus, the olfactory bulb, the pons, the choroid plexus, the nucleus pallidus, the striatum and the amygdala, the nucleus accumbens and the anterior cingulated gyrus candidate it as a promising target for genetic association studies. The biological relevance of these brain structures is reviewed by way of the focus on HTR2C activity, with a special attention paid to psychiatric disorders. Evidence from the genetic association studies that dealt with HTR2C is reviewed and discussed alongside the findings derived from the neuronatmic investigations. The reasons for the discrepancies between these two sets of reports are discussed. As a result, HTR2C is shown to play a pivotal role in many different psychiatric behaviors or psychiatric related disrupted molecular balances, nevertheless, genetic association studies brought inconsistent results so far. The most replicated association involve the feeding behavior and antipsychotic induced side effects, both weight gain and motor related: Cys23Ser (rs6318) and -759C/T (rs3813929) report the most consistent results. The lack of association found in other independent studies dampens the clinical impact of these reports. Here, we report a possible explanation for discrepant findings that is poorly or not at all usually considered, that is that HTR2C may exert different or even opposite activities in the brain depending on the structure analyzed and that mRNA editing activity may compensate possible genetically controlled functional effects. The incomplete coverage of the HTR2C variants is proposed as the best cost-benefit ratio bias to fix. The evidence of brain area specific HTR2C mRNA editing opens a debate about how the brain can differently modulate stress events, and process antidepressant treatments, in different brain areas. The mRNA editing activity on HTR2C may play a major role for the negative association results.
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Affiliation(s)
- Antonio Drago
- Institute of Psychiatry, University of Bologna, Italy
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Sensitivity of housekeeping genes in the hypothalamus to mismatch in diets between pre- and postnatal periods in mice. Neurosci Lett 2008; 447:54-7. [DOI: 10.1016/j.neulet.2008.09.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/22/2008] [Accepted: 09/24/2008] [Indexed: 11/15/2022]
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Buchholz S, Morrow AF, Coleman PL. Atypical antipsychotic-induced diabetes mellitus: an update on epidemiology and postulated mechanisms. Intern Med J 2008; 38:602-6. [DOI: 10.1111/j.1445-5994.2008.01712.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Thomsen WJ, Grottick AJ, Menzaghi F, Reyes-Saldana H, Espitia S, Yuskin D, Whelan K, Martin M, Morgan M, Chen W, Al-Shamma H, Smith B, Chalmers D, Behan D. Lorcaserin, a novel selective human 5-hydroxytryptamine2C agonist: in vitro and in vivo pharmacological characterization. J Pharmacol Exp Ther 2008; 325:577-87. [PMID: 18252809 DOI: 10.1124/jpet.107.133348] [Citation(s) in RCA: 315] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
5-Hydroxytryptamine (5-HT)(2C) receptor agonists hold promise for the treatment of obesity. In this study, we describe the in vitro and in vivo characteristics of lorcaserin [(1R)-8-chloro-2,3,4,5-tetrahydro-1-methyl-1H-3 benzazepine], a selective, high affinity 5-HT(2C) full agonist. Lorcaserin bound to human and rat 5-HT(2C) receptors with high affinity (K(i) = 15 +/- 1 nM, 29 +/- 7 nM, respectively), and it was a full agonist for the human 5-HT(2C) receptor in a functional inositol phosphate accumulation assay, with 18- and 104-fold selectivity over 5-HT(2A) and 5-HT(2B) receptors, respectively. Lorcaserin was also highly selective for human 5-HT(2C) over other human 5-HT receptors (5-HT(1A), 5-HT(3), 5-HT(4C), 5-HT5(5A), 5-HT(6), and 5-HT(7)), in addition to a panel of 67 other G protein-coupled receptors and ion channels. Lorcaserin did not compete for binding of ligands to serotonin, dopamine, and norepinephrine transporters, and it did not alter their function in vitro. Behavioral observations indicated that unlike the 5-HT(2A) agonist (+/-)-1-(2,5-dimethoxy-4-phenyl)-2-aminopropane, lorcaserin did not induce behavioral changes indicative of functional 5-HT(2A) agonist activity. Acutely, lorcaserin reduced food intake in rats, an effect that was reversed by pretreatment with the 5-HT(2C)-selective antagonist 6-chloro-5-methyl-1-[6-(2-methylpyridin-3-yloxy)pyridin-3-yl-carbamoyl]indoline (SB242,084) but not the 5-HT(2A) antagonist (R)-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol (MDL 100,907), demonstrating mediation by the 5-HT(2C) receptor. Chronic daily treatment with lorcaserin to rats maintained on a high fat diet produced dose-dependent reductions in food intake and body weight gain that were maintained during the 4-week study. Upon discontinuation, body weight returned to control levels. These data demonstrate lorcaserin to be a potent, selective, and efficacious agonist of the 5-HT(2C) receptor, with potential for the treatment of obesity.
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Affiliation(s)
- William J Thomsen
- Arena Pharmaceuticals, Inc., 6166 Nancy Ridge Dr., San Diego, CA 92121, USA.
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Differences in adipocyte long chain fatty acid uptake in Osborne-Mendel and S5B/Pl rats in response to high-fat diets. Int J Obes (Lond) 2008; 32:853-62. [PMID: 18197182 DOI: 10.1038/sj.ijo.0803792] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To determine whether strain differences in adipocyte uptake of long chain fatty acids (LCFAs) contribute to differences in weight gain by Osborne-Mendel (OM) and S5B/Pl rats (S) fed a high-fat diet (HFD). SUBJECTS Ninety-four adult (12-14-week old) male OM and S rats. MEASUREMENTS Body weight; epididymal fat pad weight; adipocyte size, number, LCFA uptake kinetics; and plasma insulin and leptin during administration of HFD or chow diets (CDs). RESULTS In both strains, rate of weight gain (RWG) was greater on an HFD than a CD; RWG on an HFD was greater, overall, in OM than S. A significant RWG increase occurred on days 1 and 2 in both strains. It was normalized in S by days 6-9 but persisted at least till day 14 in OM. RWGs were significantly correlated (P<0.001) with the V(max) for saturable adipocyte LCFA uptake (V(max)). In S, an increase in V(max) on day 1 returned to baseline by day 7 and was correlated with both plasma insulin and leptin levels throughout. In OM, a greater increase in V(max) was evident by day 2, and persisted for at least 14 days, during which both insulin and leptin levels remained elevated. Growth in epididymal fat pads on the HFD correlated with body weight, reflecting hypertrophy in OM and both hypertrophy and hyperplasia in S. CONCLUSIONS (a) Changes in V(max) contribute significantly to changes in RWG on HFDs. (b) There are important strain differences in circulating insulin and leptin responses to an HFD. (c) Both insulin and leptin responses to an HFD are closely correlated with V(max) of adipocyte fatty acid uptake in S animals, but suggest early onset of insulin resistance in OM. Thus, differences in hormonal regulation of adipocyte LCFA uptake may underlie the different responses of OM and S to HFD.
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Zammaretti F, Panzica G, Eva C. Sex-dependent regulation of hypothalamic neuropeptide Y-Y1 receptor gene expression in moderate/high fat, high-energy diet-fed mice. J Physiol 2007; 583:445-54. [PMID: 17584829 PMCID: PMC2277036 DOI: 10.1113/jphysiol.2007.133470] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In this study we investigated whether long-term consumption of a moderate/high fat (MHF), high-energy diet can affect the gene expression of the Y(1) receptor (Y(1)R) for neuropeptide Y (NPY) in the dorsomedial (DMH), ventromedial (VMH), arcuate (ARC) and paraventricular (PVN) hypothalamic nuclei of male and female Y(1)R/LacZ transgenic mice, carrying the murine Y(1)R promoter linked to the LacZ gene. MHF diet-fed male mice showed an increased consumption of metabolizable energy that was associated with a significant increase in body weight as compared with chow-fed controls. In parallel, consumption of a MHF diet for 8 weeks significantly decreased Y(1)R/LacZ transgene expression in the DMH and VMH of male mice whereas no changes were found in the ARC and PVN. Leptin treatment reduced body weight of both MHF diet- and chow-fed male mice but failed to prevent the decrease in Y(1)R/LacZ transgene expression apparent in the DMH and VMH of male mice after 8 weeks of MHF diet intake. Conversely, no significant changes of metabolizable energy intake, body weight or hypothalamic beta-galactosidase expression were found in MHF diet-fed female Y(1)R/LacZ transgenic mice. A gender-related difference of Y(1)R/LacZ transgenic mice was also observed in response to leptin treatment that failed to decrease body weight of both MHF diet- and chow-fed female mice. Results herein demonstrate that Y(1)R/LacZ FVB mice show a sexual dimorphism both on energy intake and on nucleus-specific regulation of the NPY Y(1)R system in the hypothalamus. Overall, these results provide new insights into the mechanism by which diet composition affects the hypothalamic circuit that controls energy homeostasis.
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Affiliation(s)
- Francesca Zammaretti
- Pharmacology Section, Department of Anatomy, Pharmacolgy and Forensic Medicine, University of Torino, Italy
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Buettner R, Schölmerich J, Bollheimer LC. High-fat diets: modeling the metabolic disorders of human obesity in rodents. Obesity (Silver Spring) 2007; 15:798-808. [PMID: 17426312 DOI: 10.1038/oby.2007.608] [Citation(s) in RCA: 753] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
RESEARCH METHODS AND PROCEDURES High-fat (HF) diet feeding can induce obesity and metabolic disorders in rodents that resemble the human metabolic syndrome. However, this dietary intervention is not standardized, and the HF-induced phenotype varies distinctly among different studies. The question which HF diet type is best to model the metabolic deterioration seen in human obesity remains unclear. Therefore, in this review, metabolic data obtained with different HF diet approaches are compiled. Both whole-body and organ-specific diet effects are analyzed. RESULTS On the basis of these results, we conclude that animal fats and omega-6/omega-9-containing plant oils can be used to generate an obese and insulin-resistant phenotype in rodents, whereas fish oil-fed animals do not develop these disorders. DISCUSSION Looking at the present data, it does not seem possible to define an ideal HF diet, and an exact definition of diet composition and a thorough metabolic characterization of the HF diet effects in a researcher's specific laboratory setting remains essential for metabolic studies with this model.
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Affiliation(s)
- Roland Buettner
- Department of Internal Medicine I, University of Regensburg, 93042 Regensburg, Germany.
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Primeaux SD, Barnes MJ, Bray GA. Olfactory bulbectomy increases food intake and hypothalamic neuropeptide Y in obesity-prone but not obesity-resistant rats. Behav Brain Res 2007; 180:190-6. [PMID: 17420059 PMCID: PMC1978179 DOI: 10.1016/j.bbr.2007.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2006] [Revised: 02/15/2007] [Accepted: 03/12/2007] [Indexed: 11/28/2022]
Abstract
Obese individuals often suffer from depression. The olfactory bulbectomy (OBX) model is an animal model of depression that produces behavioral, physiological, and neurochemical alterations resembling clinical depression. The OBX model was employed to assess depression-related changes in food intake in obesity-prone, Osborne-Mendel (OM) rats and obesity-resistant, S5B/Pl rats. OBX increased food intake in OM rats beginning 7 days following surgery, however, OBX did not alter food intake in S5B/Pl rats at any time point. Fourteen days following surgery, OBX significantly increased locomotor activity (total lines crossed and rears) in the openfield test in OM and S5B/Pl rats. Fifteen days following surgery, prepro-neuropeptide Y (NPY) mRNA levels were significantly increased in the hypothalamus of bulbectomized OM rats and in the medial nucleus of the amygdala of bulbectomized OM and S5B/Pl rats. OBX decreased NPY Y2 receptor mRNA levels in the hypothalamus and medial nucleus of the amygdala in OM rats, while increasing NPY Y2 receptor mRNA levels in the medial nucleus of the amygdala of S5B/Pl rats. These data indicate that though both obesity-prone and obesity-resistant strains were susceptible to the locomotor effects of OBX, food intake and hypothalamic prepro-NPY mRNA were only increased in OM rats. Therefore, strain specific alterations in hypothalamic NPY may account for increased food intake in the obesity-prone rats following OBX, and suggests a potential mechanism to explain the comorbidity of obesity and depression.
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Affiliation(s)
- Stefany D Primeaux
- Dietary Obesity Laboratory, Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, Louisiana 70808, USA.
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White CL, Ishihara Y, York DA, Bray GA. Effect of meta-chlorophenylpiperazine and cholecystokinin on food intake of Osborne-Mendel and S5B/P1 rats. Obesity (Silver Spring) 2007; 15:624-31. [PMID: 17372312 DOI: 10.1038/oby.2007.579] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To investigate whether there is a difference in sensitivity to a serotonin agonist, meta-chlorophenylpiperazine (mCPP), or cholecystokinin (CCK-8), an intestinal hormone that inhibits food intake, between the Osborne-Mendel (OM) rat, which becomes obese eating a high-fat diet, and the S5B/Pl (S5B) rat, which is resistant to dietary-induced obesity. RESEARCH METHODS AND PROCEDURES OM and S5B rats were adapted to either a high-saturated-fat diet (56% energy as fat) or a low-fat diet (10% energy as fat) or to both for 14 days and then treated with several doses of mCPP or CCK-8. RESULTS Treatment with mCPP reduced food intake in both strains of rats. The dose-response curve showed that the OM rats had an increased sensitivity to the serotonergic agonist. Animals eating the high-fat diet had less response to mCPP; and in the S5B rats, the response was significantly reduced. After treatment with CCK-8, there was a similar dose-related suppression of food intake in both the OM and S5B rats. DISCUSSION These data are consistent with the hypothesis that the serotonin system in the S5B rat has a greater activity that could act to inhibit fat intake. The response to CCK was not significantly affected by strain or diet.
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Affiliation(s)
- Christy L White
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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Beck B. Neuropeptide Y in normal eating and in genetic and dietary-induced obesity. Philos Trans R Soc Lond B Biol Sci 2007; 361:1159-85. [PMID: 16874931 PMCID: PMC1642692 DOI: 10.1098/rstb.2006.1855] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuropeptide Y (NPY) is one the most potent orexigenic peptides found in the brain. It stimulates food intake with a preferential effect on carbohydrate intake. It decreases latency to eat, increases motivation to eat and delays satiety by augmenting meal size. The effects on feeding are mediated through at least two receptors, the Y1 and Y5 receptors. The NPY system for feeding regulation is mostly located in the hypothalamus. It is formed of the arcuate nucleus (ARC), where the peptide is synthesized, and the paraventricular (PVN), dorsomedial (DMN) and ventromedial (VMN) nuclei and perifornical area where it is active. This activity is modulated by the hindbrain and limbic structures. It is dependent on energy availability, e.g. upregulation with food deprivation or restriction, and return to baseline with refeeding. It is also sensitive to diet composition with variable effects of carbohydrates and fats. Leptin signalling and glucose sensing which are directly linked to diet type are the most important factors involved in its regulation. Absence of leptin signalling in obesity models due to gene mutation either at the receptor level, as in the Zucker rat, the Koletsky rat or the db/db mouse, or at the peptide level, as in ob/ob mouse, is associated with increased mRNA abundance, peptide content and/or release in the ARC or PVN. Other genetic obesity models, such as the Otsuka-Long-Evans-Tokushima Fatty rat, the agouti mouse or the tubby mouse, are characterized by a diminution in NPY expression in the ARC nucleus and by a significant increase in the DMN. Further studies are necessary to determine the exact role of NPY in these latter models. Long-term exposure to high-fat or high-energy palatable diets leads to the development of adiposity and is associated with a decrease in hypothalamic NPY content or expression, consistent with the existence of a counter-regulatory mechanism to diminish energy intake and limit obesity development. On the other hand, an overactive NPY system (increased mRNA expression in the ARC associated with an upregulation of the receptors) is characteristic of rats or rodent strains sensitive to dietary-induced obesity. Finally, NPY appears to play an important role in body weight and feeding regulation, and while it does not constitute the only target for drug treatment of obesity, it may nevertheless provide a useful target in conjunction with others.
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Affiliation(s)
- B Beck
- Université Henri Poincaré, Neurocal, Nancy, France.
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Barnes MJ, Holmes G, Primeaux SD, York DA, Bray GA. Increased expression of mu opioid receptors in animals susceptible to diet-induced obesity. Peptides 2006; 27:3292-8. [PMID: 16996647 DOI: 10.1016/j.peptides.2006.08.008] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 08/04/2006] [Accepted: 08/07/2006] [Indexed: 11/22/2022]
Abstract
Stimulation of mu opioid receptors preferentially increases the intake of a high fat diet. In this paper we investigated whether there was a difference in the expression of mu opioid receptors between animals susceptible (Osborne-Mendel) or resistant (S5B/Pl) to obesity induced by eating a high fat diet. Immunohistochemical studies demonstrated that Osborne-Mendel rats eating a chow diet had an increased number of mu opioid receptors in the arcuate nucleus when compared to S5B/Pl rats. These immunohistochemical findings were supported by Real Time-PCR which demonstrated that the mRNA level of mu opioid receptors was also increased in the hypothalamus of Osborne-Mendel rats compared to S5B/Pl rats. Low doses of the mu opioid receptor agonist DAMGO [d-Ala(2)-N-Me-Phe(4)-Glycol(5)]-enkephalin administered to Osborne-Mendel rats caused a significant increase in the preference for a diet high in fat. The same doses of DAMGO switched the diet preference of S5B/Pl rats to high fat but did not significantly increase food intake. The combination of these findings suggests that the increased levels of hypothalamic mu opioid receptors in Osborne-Mendel rats may contribute to their preference for a diet high in fat and increase their susceptibility to becoming obese.
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Affiliation(s)
- Maria J Barnes
- Pennington Biomedical Research Center, Dietary Obesity Laboratory, Baton Rouge, LA 70808, USA.
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Heijboer AC, Voshol PJ, Donga E, van Eden CG, Havekes LM, Romijn JA, Pijl H, Corssmit EPM. High fat diet induced hepatic insulin resistance is not related to changes in hypothalamic mRNA expression of NPY, AgRP, POMC and CART in mice. Peptides 2005; 26:2554-8. [PMID: 15979206 DOI: 10.1016/j.peptides.2005.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 05/19/2005] [Accepted: 05/20/2005] [Indexed: 12/20/2022]
Abstract
The hypothalamic circuitry, apart from its impact on food intake, modulates insulin sensitivity to adapt metabolic conditions in the face of environmental fluctuations in nutrient availability. The purpose of the present study was to investigate the effects of 2 weeks high fat feeding in wildtype mice on (1) insulin sensitivity and triglyceride accumulation in liver and muscle in relation to (2) mRNA expression levels of Neuropeptide Y (NPY), Agouti-related protein (AgRP), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART) in the hypothalamus. Two weeks of high fat feeding induced hepatic insulin resistance in the presence of increased hepatic triglyceride accumulation. In muscle, however, 2 weeks of high fat feeding did not result in changes in insulin sensitivity or in triglyceride content. mRNA expression levels of NPY, AgRP, POMC, and CART in the hypothalamus were not different between the groups. This study shows that 2 weeks of high fat feeding in mice does not affect mRNA expression levels of NPY, AgRP, POMC or CART, in the whole hypothalamus, despite induction of hepatic, but not peripheral, insulin resistance. Therefore, a major physiological role of these neuroendocrine factors in the induction of hepatic insulin resistance during a high fat diet seems less likely.
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Affiliation(s)
- A C Heijboer
- Department of Endocrinology and Metabolic Diseases, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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White CL, Ishii Y, Mendoza T, Upton N, Stasi LP, Bray GA, York DA. Effect of a selective OX1R antagonist on food intake and body weight in two strains of rats that differ in susceptibility to dietary-induced obesity. Peptides 2005; 26:2331-8. [PMID: 15893404 DOI: 10.1016/j.peptides.2005.03.042] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/24/2005] [Accepted: 03/24/2005] [Indexed: 11/25/2022]
Abstract
An orexin-1 receptor antagonist decreases food intake whereas orexin-A selectively induces hyperphagia to a high-fat diet. In the present study, we evaluated the effect of an orexin antagonist in two strains of rats that differ in their sensitivity to becoming obese while eating a high-fat diet. Male Osborne-Mendel (OM) and S5B/Pl (S5B) rats were treated acutely with an orexin-1 receptor antagonist (SB-334867), after adaptation to either a high-fat (56% fat energy) diet or a low-fat (10% fat energy) diet that were equicaloric for protein (24% energy). Ad libitum fed rats were injected intraperitoneally with SB-334867 at doses of 3, 10 or 30 mg/kg, or vehicle at the beginning of the dark cycle, and food intake and body weight were measured. Hypothalamic prepro-orexin and orexin-1 receptor mRNA expression were analyzed in OM and S5B rats fed at a high-fat or low-fat diet for two weeks. SB-334867 significantly decreased food intake in both strains of rats eating the high-fat diet but only in the OM rats eating the low fat diet. The effect was greatest at 12 and 24 h. Body weight was also reduced in OM rats 1d after injection of SB-334867 but not in the S5B rats. Prepro-orexin and orexin-1 receptor expression levels did not differ between strains or diets. These experiments demonstrate that an orexin antagonist (SB-334867) reduces food intake and has a greater effect in a rat strain that is susceptible to dietary-induced obesity, than in a resistant strain.
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Affiliation(s)
- C L White
- Pennington Biomedical Research Center, Experimental Obesity laboratory, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA.
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McCarthy S, Mottagui-Tabar S, Mizuno Y, Sennblad B, Hoffstedt J, Arner P, Wahlestedt C, Andersson B. Complex HTR2C linkage disequilibrium and promoter associations with body mass index and serum leptin. Hum Genet 2005; 117:545-57. [PMID: 16021472 DOI: 10.1007/s00439-005-1328-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Accepted: 04/14/2005] [Indexed: 10/25/2022]
Abstract
The occurrence of obesity, eating disorders, and related diseases has increased in many parts of the world. Given that few strong genetic factors have been found, it is clear that these are complex multi-factorial diseases. The serotonin receptor 2C, a member of the 5-HTergic system, has been implicated in the control of phagia and obesity. We report a detailed investigation of linkage disequilibrium (LD) within and between the HTR2C promoter and the flanking sequences around a commonly utilized marker in the second coding exon of HTR2C. We suggest that inconsistent associations between HTR2C and several phenotypes, including obesity, may be due to the LD pattern across the gene in which recombination and gene conversion have been influential. The nucleotide and haplotype distribution is consistent with that of the neutral mutation model. The number of haplotypes suggests demographic influences or over dominant selection that may have a function in HTR2C expression. Using the fine LD pattern, we describe a possible association with promoter haplotypes and diplotypes, including a GT microsatellite, and body mass index (BMI) > or =30 kgm(-2) (P<0.0001). SNP -995G>A heterozygotes, as well as promoter diplotypes, were found to marginally influence higher serum leptin corrected for percentage body fat (P=0.01), which might suggest that these subjects are leptin resistant. Our results complement previous studies of HTR2C in both mice and humans, and suggest the importance of genetic variation and elucidating the fine LD structure in uncovering the genetic factors of obesity.
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Affiliation(s)
- Shane McCarthy
- Center for Genomics and Bioinformatics, Karolinska Institutet, Berzelius Väg 35, 17177 Stockholm, Sweden.
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Vallejo-Cremades MT, Gómez-García L, Chacatas-Cortesao M, Moreno C, Sánchez M, De Miguel E, Gómez De Segura IA. Enriched protein diet-modified ghrelin expression and secretion in rats. ACTA ACUST UNITED AC 2004; 121:113-9. [PMID: 15256281 DOI: 10.1016/j.regpep.2004.04.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2003] [Revised: 04/22/2004] [Accepted: 04/29/2004] [Indexed: 11/22/2022]
Abstract
Gastrointestinal (GI) integrity and function are regulated by nutrition and growth factors. The discovery of ghrelin, a natural growth hormone (GH) secretagogue produced by the gastrointestinal (GI) tract, is a potential link between diet and growth signals. The aim of this study was to evaluate macronutrient effect on ghrelin expression and secretion in addition to some possible function in intestinal trophic status. Wistar rats were fed a high-carbohydrate, high-protein (HP), high-fat or standard (St) diet. Animals received the same daily food volume and caloric intake. After 7 days, animals were fasted for 24 h and blood and tissue samples were obtained just before feeding or at 2 or 6 h after feeding. Fasting high-protein-fed rats had higher ghrelin plasma levels than with rats fed the high-carbohydrate, high-fat or standard diets. Two-hours after refeeding, ghrelin plasma levels had decreased in all groups with a slight recovery at 6 h after refeeding, except in the high-protein group. Ghrelin plasma levels in rats fed with the high-protein diet correlated negatively with their GH and insulin-like growth factor 1 (IGF-1) plasma concentrations which were also the lowest among the study groups. In conclusion, ghrelin secretion was nutritionally manipulated because a protein-enriched diet increased its levels.
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Affiliation(s)
- M T Vallejo-Cremades
- Research Unit, Servicio de Cirugía Experimental, Hospital Universitario La Paz, Paseo de la Castellana 261, 28046 Madrid, Spain
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Huang XF, Han M, Storlien LH. Differential expression of 5-HT2A and 5-HT2C receptor mRNAs in mice prone, or resistant, to chronic high-fat diet-induced obesity. ACTA ACUST UNITED AC 2004; 127:39-47. [PMID: 15306119 DOI: 10.1016/j.molbrainres.2004.05.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2004] [Indexed: 11/24/2022]
Abstract
The present study examined the levels of 5-HT(2A) and 5-HT(2C) (2A and 2C receptors of 5-hydroxytryptamine; serotonin) receptor messenger RNA (mRNA) expressions in the brain of chronic high-fat diet-induced obese (DIO) and obese-resistant (DR) mice. Thirty-one mice were used in this study. Twenty-four mice were fed with a high-fat diet (HF: 40% of calories from fat) for 4 weeks and then classified as the DIO (n = 8) or DR (n = 8) mice according to the highest and lowest body weight (BW) gainers. Seven mice were placed on a low-fat diet (LF: 10% of calories from fat) and were used as controls. After 20 weeks of feeding, the visceral fat accumulation was 620 +/- 42 mg in the DIO group versus 198 +/- 89 mg in the DR and 84 +/- 18 mg in the LF groups. Using quantitative in situ hybridization techniques, levels of 2A and 2C serotonin (5-HT) receptor mRNAs were measured in multiple brain sections of mice from the three groups. Most regions did not differ between groups but, importantly, the DIO mice had a significantly higher level of 5-HT(2A) receptor mRNA expression in the olfactory nucleus (Olf) compared to the DR and LF mice (+30% and +37%, respectively). The levels of Olf 5-HT(2A) receptor mRNA expression were related to body fat mass. The level of 5-HT(2C) mRNA receptor expression in the ventromedial hypothalamic (VMH) nucleus was 40% higher in the DIO mice than in the LF mice. Furthermore, the 5-HT(2C) receptor mRNA expression in the posterodorsal part of the medial amygdaloid (MePD) nucleus was 25% higher in the DIO mice than in the DR mice. The level of VMH 5-HT(2C) receptor mRNA expression was correlated with body fat mass. In conclusion, this study has demonstrated differentially regulated levels of the 5-HT(2A) and 5-HT(2C) receptor mRNA expressions in the specific brain regions of the DIO and DR mice. It provides neural anatomical bases that the 5-HT(2C) receptors positively influence satiety center (VMH) while the 5-HT(2A) receptor regulates olfactory sensory effects. The findings also assist us to understand the role of these receptors in mice susceptible or resistant to diet-induced obesity.
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MESH Headings
- Animals
- Body Weight/physiology
- Brain/anatomy & histology
- Brain/metabolism
- Diet, Fat-Restricted
- Dietary Fats/adverse effects
- Eating/physiology
- Energy Intake/physiology
- Fats/metabolism
- Gene Expression Regulation
- In Situ Hybridization
- Male
- Mice
- Obesity/etiology
- Obesity/genetics
- Obesity/metabolism
- RNA, Messenger/metabolism
- Receptor, Serotonin, 5-HT2A/genetics
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Statistics as Topic
- Time Factors
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Affiliation(s)
- Xu-Feng Huang
- Molecular Neurobiology Laboratory, Department of Biomedical Science, University of Wollongong, Wollongong, NSW 2522, Australia.
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Abstract
Energy balance is maintained via a homeostatic system involving both the brain and the periphery. A key component of this system is the hypothalamus. Over the past two decades, major advances have been made in identifying an increasing number of peptides within the hypothalamus that contribute to the process of energy homeostasis. Under stable conditions, equilibrium exists between anabolic peptides that stimulate feeding behavior, as well as decrease energy expenditure and lipid utilization in favor of fat storage, and catabolic peptides that attenuate food intake, while stimulating sympathetic nervous system (SNS) activity and restricting fat deposition by increasing lipid metabolism. The equilibrium between these neuropeptides is dynamic in nature. It shifts across the day-night cycle and from day to day and also in response to dietary challenges as well as peripheral energy stores. These shifts occur in close relation to circulating levels of the hormones, leptin, insulin, ghrelin and corticosterone, and also the nutrients, glucose and lipids. These circulating factors together with neural processes are primary signals relaying information regarding the availability of fuels needed for current cellular demand, in addition to the level of stored fuels needed for long-term use. Together, these signals have profound impact on the expression and production of neuropeptides that, in turn, initiate the appropriate anabolic or catabolic responses for restoring equilibrium. In this review, we summarize the evidence obtained on nine peptides in the hypothalamus that have emerged as key players in this process. Data from behavioral, physiological, pharmacological and genetic studies are described and consolidated in an attempt to formulate a clear statement on the underlying function of each of these peptides and also on how they work together to create and maintain energy homeostasis.
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Affiliation(s)
- Sarah F Leibowitz
- Laboratory of Behavioral Neurobiology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
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