1
|
Mitchell CS, Goodman EK, Tedesco CR, Nguyen K, Zhang L, Herzog H, Begg DP. The Effect of Dietary Fat and Sucrose on Cognitive Functioning in Mice Lacking Insulin Signaling in Neuropeptide Y Neurons. Front Physiol 2022; 13:841935. [PMID: 35557971 PMCID: PMC9086626 DOI: 10.3389/fphys.2022.841935] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/11/2022] [Indexed: 12/23/2022] Open
Abstract
Obesogenic diets can produce hippocampal insulin resistance and impairments to hippocampal-dependent cognition. This study investigated the effect of disrupted insulin signaling in Neuropeptide Y (NPY) neurons on diet-induced deficits in hippocampal-dependent memory. Wild-type mice and mice that had a targeted knockout of insulin receptors on NPY cells (IRlox/lox;NPYCre/+) were given ad libitum access to a high-fat diet (high fat; HF), 10% sucrose solution (high sugar; HS), both high-fat diet and sucrose solution (high fat, high sugar; HFHS), or a normal fat control chow for 12 weeks. Mice were tested in the Morris Water Maze (MWM), a hippocampal-dependent spatial memory task. Glucose homeostasis was assessed via a glucose tolerance test. Independent of genotype, consumption of HF, but not HS, diet increased energy intake, body weight, and plasma leptin, and impaired glucose tolerance. Disrupted insulin signaling in NPY cells and dietary interventions did not significantly affect the ability of mice to learn the location of the platform in the MWM. However, for IRlox/lox control mice, consumption of HF, but not HS, diet resulted in reduced time spent in the target quadrant during the probe trial, suggesting a hippocampal-dependent memory deficit. IRlox/lox;NPYCre/+ mice had poor performance in the probe trial regardless of diet, suggesting a floor effect. This study did not find adverse effects of chronic sucrose intake on metabolic outcomes or hippocampal-dependent memory. These data also suggest that the effects of HF diet on hippocampal-dependent memory may be dependent on insulin signaling in hippocampal NPY cells.
Collapse
Affiliation(s)
| | | | | | - Kathy Nguyen
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| | - Lei Zhang
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Herbert Herzog
- Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
| | - Denovan P Begg
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| |
Collapse
|
2
|
Goodman EK, Mitchell CS, Teo JD, Gladding JM, Abbott KN, Rafiei N, Zhang L, Herzog H, Begg DP. The effect of insulin receptor deletion in neuropeptide Y neurons on hippocampal dependent cognitive function in aging mice. J Integr Neurosci 2022; 21:6. [DOI: 10.31083/j.jin2101006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/29/2021] [Accepted: 08/27/2021] [Indexed: 11/06/2022] Open
|
3
|
Homberg JR, Adan RAH, Alenina N, Asiminas A, Bader M, Beckers T, Begg DP, Blokland A, Burger ME, van Dijk G, Eisel ULM, Elgersma Y, Englitz B, Fernandez-Ruiz A, Fitzsimons CP, van Dam AM, Gass P, Grandjean J, Havekes R, Henckens MJAG, Herden C, Hut RA, Jarrett W, Jeffrey K, Jezova D, Kalsbeek A, Kamermans M, Kas MJ, Kasri NN, Kiliaan AJ, Kolk SM, Korosi A, Korte SM, Kozicz T, Kushner SA, Leech K, Lesch KP, Lesscher H, Lucassen PJ, Luthi A, Ma L, Mallien AS, Meerlo P, Mejias JF, Meye FJ, Mitchell AS, Mul JD, Olcese U, González AO, Olivier JDA, Pasqualetti M, Pennartz CMA, Popik P, Prickaerts J, de la Prida LM, Ribeiro S, Roozendaal B, Rossato JI, Salari AA, Schoemaker RG, Smit AB, Vanderschuren LJMJ, Takeuchi T, van der Veen R, Smidt MP, Vyazovskiy VV, Wiesmann M, Wierenga CJ, Williams B, Willuhn I, Wöhr M, Wolvekamp M, van der Zee EA, Genzel L. The continued need for animals to advance brain research. Neuron 2021; 109:2374-2379. [PMID: 34352213 DOI: 10.1016/j.neuron.2021.07.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Policymakers aim to move toward animal-free alternatives for scientific research and have introduced very strict regulations for animal research. We argue that, for neuroscience research, until viable and translational alternatives become available and the value of these alternatives has been proven, the use of animals should not be compromised.
Collapse
Affiliation(s)
| | - Roger A H Adan
- University Medical Center Utrecht, Utrecht, the Netherlands
| | - Natalia Alenina
- The Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Antonis Asiminas
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, UK; Center for Translational Neuromedicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Michael Bader
- The Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin, Germany
| | - Tom Beckers
- KU Leuven, Leuven Brain Institute and Faculty of Psychology and Educational Sciences, Leuven, Belgium
| | - Denovan P Begg
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| | | | | | - Gertjan van Dijk
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Ulrich L M Eisel
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Ype Elgersma
- Erasmus Medical Center, Rotterdam, the Netherlands
| | | | | | - Carlos P Fitzsimons
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Anne-Marie van Dam
- Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Amsterdam University Medical Center, Free University, Amsterdam, the Netherlands
| | - Peter Gass
- Central Institute of Mental Health, University of Heidelberg, Mannheim Faculty, Mannheim, Germany
| | | | - Robbert Havekes
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | | | - Christiane Herden
- Institute of Veterinary Pathology, Gießen, Gießen, Germany; Center of Mind Brain and Behavior (CMBB), Philipps-University of Marburg and Justus-Liebig-University Gießen, Marburg, Germany
| | - Roelof A Hut
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | | | - Kate Jeffrey
- Institute of Behavioural Neuroscience, University College London, London WC1H 0AP, UK
| | - Daniela Jezova
- Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Martien J Kas
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | | | | | | | - Aniko Korosi
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - S Mechiel Korte
- Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | | | | | - Kirk Leech
- European Animal Research Association, London, UK
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, Center of Mental Health, University of Würzburg, Würzburg, Germany; Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia; Department of Neuropsychology and Psychiatry, School for Mental Health and Neuroscience (MHeNS), Maastricht University, Maastricht, the Netherlands
| | - Heidi Lesscher
- Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands
| | - Paul J Lucassen
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Anita Luthi
- Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Liya Ma
- Radboud University, Nijmegen, the Netherlands
| | - Anne S Mallien
- Central Institute of Mental Health, University of Heidelberg, Mannheim Faculty, Mannheim, Germany
| | - Peter Meerlo
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Jorge F Mejias
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Frank J Meye
- University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Joram D Mul
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Umberto Olcese
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | | | - Jocelien D A Olivier
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | | | - Cyriel M A Pennartz
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Piotr Popik
- Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków 31-343, Poland
| | | | - Liset M de la Prida
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Sidarta Ribeiro
- Brain Institute, Federal University of Rio Grande do Norte, Natal, Brazil
| | | | - Janine I Rossato
- Department of Physiology, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Ali-Akbar Salari
- Salari Institute of Cognitive and Behavioral Disorders (SICBD), Karaj, Alborz, Iran
| | - Regien G Schoemaker
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - August B Smit
- Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | | | - Tomonori Takeuchi
- Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
| | - Rixt van der Veen
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | - Marten P Smidt
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
| | | | | | - Corette J Wierenga
- Biology Department, Faculty of Science, Utrecht University, Utrecht, the Netherlands
| | | | - Ingo Willuhn
- Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Markus Wöhr
- Center of Mind Brain and Behavior (CMBB), Philipps-University of Marburg and Justus-Liebig-University Gießen, Marburg, Germany; Philipps-University of Marburg, Faculty of Psychology, Experimental and Biological Psychology, Behavioral Neuroscience, Marburg, Germany; KU Leuven, Leuven Brain Institute and Faculty of Psychology and Educational Sciences, Leuven, Belgium
| | | | - Eddy A van der Zee
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Lisa Genzel
- Radboud University, Nijmegen, the Netherlands.
| |
Collapse
|
4
|
Mitchell CS, Premaratna SD, Bennett G, Lambrou M, Stahl LA, Jois M, Barber E, Antoniadis CP, Woods SC, Cameron-Smith D, Weisinger RS, Begg DP. Inhibition of the Renin-Angiotensin System Reduces Gene Expression of Inflammatory Mediators in Adipose Tissue Independent of Energy Balance. Front Endocrinol (Lausanne) 2021; 12:682726. [PMID: 34149621 PMCID: PMC8206808 DOI: 10.3389/fendo.2021.682726] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 05/12/2021] [Indexed: 12/30/2022] Open
Abstract
Obesity is a growing health problem worldwide. The renin-angiotensin system (RAS) is present in adipose tissue, and evidence suggests that it is involved in both diet-induced obesity and the inflammation associated with obesity. The present experiments determined the effect of (1) different angiotensin-converting enzyme (ACE) inhibitors (captopril, perindopril, enalapril) and angiotensin receptor blockers (ARBs: telmisartan, losartan) on adiposity of mice fed a high-fat diet for 28 days (2); acute treatment with the ACE-inhibitor captopril on gene expression of inflammatory markers in mice fed a high-fat diet (HFD); and (3) short-term (2 days) and chronic (28 days) treatment of ACE-inhibition on energy expenditure (EE) and energy balance in mice fed HFD ad libitum (AL), as well as receiving HFD limited to the amount of calories eaten by controls (pair-fed (PF) group). Body weight, food intake, adiposity and plasma leptin were lower in ACE inhibitor or ARB-treated groups over 28 days compared with HFD untreated mice. Short-term treatment with captopril led to increased EE relative to the level in the PF group. After 28 days, EE was lower in both captopril-treated and PF mice compared with AL, but the effect was greater in the captopril-treated group. Adiponectin was elevated in captopril-treated mice, but not in PF mice, after both 2 and 28 days. Additionally, acute RAS blockade in HFD-fed mice reduced mRNA expression for MCP-1, IL-6, TLR4, and leptin in adipose tissue relative to values in untreated groups. These data demonstrate that ACE inhibition and angiotensin receptor blockade reduce food intake to produce weight loss and suggest that the anti-inflammatory effects of ACE inhibition may be independent of weight loss.
Collapse
Affiliation(s)
| | - Shirmila D. Premaratna
- Department of Animal, Plant and Soil Sciences, School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| | - Garth Bennett
- School of Psychological Science, La Trobe University, Melbourne, VIC, Australia
| | - Maria Lambrou
- School of Psychological Science, La Trobe University, Melbourne, VIC, Australia
| | - Lauren A. Stahl
- School of Psychological Science, La Trobe University, Melbourne, VIC, Australia
| | - Markandeya Jois
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Melbourne, VIC, Australia
| | - Elizabeth Barber
- Department of Nutrition, Dietetics and Food, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | | | - Stephen C. Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH, United States
| | - David Cameron-Smith
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research, Singapore, Singapore
| | | | | |
Collapse
|
5
|
Sucquart IE, Nagarkar R, Edwards MC, Rodriguez Paris V, Aflatounian A, Bertoldo MJ, Campbell RE, Gilchrist RB, Begg DP, Handelsman DJ, Padmanabhan V, Anderson RA, Walters KA. Neurokinin 3 Receptor Antagonism Ameliorates Key Metabolic Features in a Hyperandrogenic PCOS Mouse Model. Endocrinology 2021; 162:6125280. [PMID: 33522579 DOI: 10.1210/endocr/bqab020] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Polycystic ovary syndrome (PCOS) is a prevalent endocrine condition characterized by a range of endocrine, reproductive, and metabolic abnormalities. At present, management of women with PCOS is suboptimal as treatment is only symptomatic. Clinical and experimental advances in our understanding of PCOS etiology support a pivotal role for androgen neuroendocrine actions in PCOS pathogenesis. Hyperandrogenism is a key PCOS trait and androgen actions play a role in regulating the kisspeptin-/neurokinin B-/dynorphin (KNDy) system. This study aimed to investigate if targeted antagonism of neurokinin B signaling through the neurokinin 3 receptor (NK3R) would reverse PCOS traits in a dihydrotestosterone (DHT)-induced mouse model of PCOS. After 3 months, DHT exposure induced key reproductive PCOS traits of cycle irregularity and ovulatory dysfunction, and PCOS-like metabolic traits including increased body weight; white and brown fat pad weights; fasting serum triglyceride and glucose levels, and blood glucose incremental area under the curve. Treatment with a NK3R antagonist (MLE4901) did not impact the observed reproductive defects. In contrast, following NK3R antagonist treatment, PCOS-like females displayed decreased total body weight, adiposity, and adipocyte hypertrophy, but increased respiratory exchange ratio, suggesting NK3R antagonism altered the metabolic status of the PCOS-like females. NK3R antagonism did not improve circulating serum triglyceride or fasted glucose levels. Collectively, these findings demonstrate that NK3R antagonism may be beneficial in the treatment of adverse metabolic features associated with PCOS and support neuroendocrine targeting in the development of novel therapeutic strategies for PCOS.
Collapse
Affiliation(s)
- Irene E Sucquart
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ruchi Nagarkar
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Melissa C Edwards
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Valentina Rodriguez Paris
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ali Aflatounian
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Michael J Bertoldo
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Rebecca E Campbell
- Centre of Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Robert B Gilchrist
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| | - Denovan P Begg
- Department of Behavioural Neuroscience, School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia
| | - David J Handelsman
- Andrology Laboratory, ANZAC Research Institute, University of Sydney, Concord Hospital, NSW 2139, Australia
| | | | - Richard A Anderson
- Medical Research Council Centre for Reproductive Health, University of Edinburgh, Edinburgh EH16 4TJ, UK
| | - Kirsty A Walters
- Fertility and Research Centre, School of Women's & Children's Health, University of New South Wales, Sydney, NSW 2052, Australia
| |
Collapse
|
6
|
Mitchell CS, Begg DP. The regulation of food intake by insulin in the central nervous system. J Neuroendocrinol 2021; 33:e12952. [PMID: 33656205 DOI: 10.1111/jne.12952] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/31/2021] [Accepted: 02/03/2021] [Indexed: 01/02/2023]
Abstract
Food intake and energy expenditure are regulated by peripheral signals providing feedback on nutrient status and adiposity to the central nervous system. One of these signals is the pancreatic hormone, insulin. Unlike peripheral administration of insulin, which often causes weight gain, central administration of insulin leads to a reduction in food intake and body weight when administered long-term. This is a result of feedback processes in regions of the brain that regulate food intake. Within the hypothalamus, the arcuate nucleus (ARC) contains subpopulations of neurones that produce orexinergic neuropeptides agouti-related peptide (AgRP)/neuropeptide Y (NPY) and anorexigenic neuropeptides, pro-opiomelanocortin (POMC)/cocaine- and amphetamine-regulated transcript (CART). Intracerebroventricular infusion of insulin down-regulates the expression of AgRP/NPY at the same time as up-regulating expression of POMC/CART. Recent evidence suggests that insulin activity within the amygdala may play an important role in regulating energy balance. Insulin infusion into the central nucleus of the amygdala (CeA) can decrease food intake, possibly by modulating activity of NPY and other neurone subpopulations. Insulin signalling within the CeA can also influence stress-induced obesity. Overall, it is evident that the CeA is a critical target for insulin signalling and the regulation of energy balance.
Collapse
Affiliation(s)
| | - Denovan P Begg
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| |
Collapse
|
7
|
Begg DP, Sinclair AJ, Weisinger RS. Impaired Fluid Intake, but Not Sodium Appetite, in Aged Rats Is Mediated by the Cyclooxygenase-Prostaglandin E 2 Pathway. Front Aging Neurosci 2020; 12:19. [PMID: 32184716 PMCID: PMC7059018 DOI: 10.3389/fnagi.2020.00019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 01/20/2020] [Indexed: 01/22/2023] Open
Abstract
Aging results in decreased fluid intake following dehydration and other dipsogenic stimuli; similar reductions in sodium intake have also been observed with aging. Given that cyclooxygenase (COX)-derived prostanoids are elevated in aged rats in the midbrain and proinflammatory prostanoids are known to decrease fluid intake in dehydrated rats, the aim of this study was to determine if the reductions of fluid intake and sodium intake in aging are mediated by proinflammatory eicosanoid signaling. Therefore, we examined the effect of acute COX inhibition in adult (4 months-old) and aged (30 months-old) rats prior to ingestive behavior challenges. COX inhibition, using acetylsalicylic acid (ASA), increased fluid intake in aged, but not adult, rats in response to 24-h dehydration. ASA had no effect on salt intake following sodium depletion and ASA did not change basal fluid or sodium consumption in either age group. Hypothalamic COX-1 and -2, prostaglandin E synthase (PGES) and inducible nitric oxide synthase (iNOS) mRNA expression were all elevated in aged animals, leading to elevated PGE2 levels. COX expression in the hypothalamus was reduced by ASA treatment in rats of both ages resulting in reduced PGE2 levels in aged ASA treated animals. These data indicate that the reduced fluid intake that occurs in aging is due to increased COX-PGE2-mediated inflammation. However, the reduced sodium intake in these animals appears to occur via an alternate mechanism.
Collapse
Affiliation(s)
- Denovan P Begg
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| | | | | |
Collapse
|
8
|
Goulter N, Kimonis ER, Denson TF, Begg DP. Female primary and secondary psychopathic variants show distinct endocrine and psychophysiological profiles. Psychoneuroendocrinology 2019; 104:7-17. [PMID: 30784904 DOI: 10.1016/j.psyneuen.2019.02.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 12/21/2018] [Accepted: 02/12/2019] [Indexed: 12/30/2022]
Abstract
Research with predominantly male samples supports primary and secondary developmental pathways to psychopathy that are phenotypically indistinguishable on aggressive and antisocial behavior. The aim of this study was to examine whether female variants of psychopathy show divergent endocrine (i.e., cortisol, dehydroepiandrosterone [DHEA], testosterone, and their ratios) and psychophysiological (i.e., heart rate variability [HRV]) reactivity to social provocation. We also tested whether variants differed on reactive aggression when performing a competitive reaction time task against the fictitious participant who previously insulted them. Latent profile analyses on 101 undergraduate women oversampled for high psychopathic traits identified a high-anxious, maltreated secondary variant (n=64) and a low-anxious primary variant (n=37). Although variants did not differ on aggression, secondary variants showed higher cortisol, testosterone, cortisol-to-DHEA ratios, and HRV following social provocation relative to primary variants. Findings suggest that the neurobiological mechanisms underpinning aggression in psychopathy may differ between women on primary versus secondary developmental pathways.
Collapse
Affiliation(s)
- Natalie Goulter
- Department of Psychology, Simon Fraser University, Burnaby, Canada.
| | - Eva R Kimonis
- School of Psychology, The University of New South Wales, Sydney, Australia; Salivary Bioscience Research Centre, The University of New South Wales, Sydney, Australia
| | - Thomas F Denson
- School of Psychology, The University of New South Wales, Sydney, Australia; Salivary Bioscience Research Centre, The University of New South Wales, Sydney, Australia
| | - Denovan P Begg
- School of Psychology, The University of New South Wales, Sydney, Australia; Salivary Bioscience Research Centre, The University of New South Wales, Sydney, Australia
| |
Collapse
|
9
|
Begg DP. Insulin transport and activity in the central nervous system. Obes Res Clin Pract 2019. [DOI: 10.1016/j.orcp.2016.10.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
10
|
Gladding JM, Abbott KN, Antoniadis CP, Stuart A, Begg DP. The Effect of Intrahippocampal Insulin Infusion on Spatial Cognitive Function and Markers of Neuroinflammation in Diet-induced Obesity. Front Endocrinol (Lausanne) 2018; 9:752. [PMID: 30619085 PMCID: PMC6297211 DOI: 10.3389/fendo.2018.00752] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/27/2018] [Indexed: 11/13/2022] Open
Abstract
Obesity and high fat diet consumption contribute to the development of metabolic disorders, insulin resistance, neuroinflammation, and cognitive impairments. CNS administration of insulin into the brain can attenuate these cognitive impairments. The present study investigated whether hippocampal-dependent spatial memory impairments in a dietary induced mouse model of obesity could be improved by the direct administration of insulin into the hippocampus and whether this was associated with markers of hippocampal inflammation. C57Bl/6J mice consumed a low fat or high fat diet for 16 weeks and continuous intrahippocampal saline or insulin infusion for the final 4 weeks, during a period of behavioral testing, before gene expression analysis was performed. The high fat diet group demonstrated poorer spatial memory performance in the Morris water maze and Y-maze, supporting the hypothesis that high fat diet leads to hippocampal dependent cognitive impairment. Insulin infusion into the hippocampus reversed the deficit of high fat diet consumption on both of the tasks. Increased expression of inflammatory markers was detected in the hippocampus in the high fat diet group and expression of these markers was ameliorated in insulin infused mice. This demonstrates that CNS insulin can improve hippocampal-dependent memory and that hippocampal inflammation may be a factor in the development of cognitive deficits associated with diet-induced obesity. Furthermore, these data suggest that insulin may act to attenuate high fat diet induced cognitive deficits by reducing neuroinflammation.
Collapse
Affiliation(s)
- Joanne M. Gladding
- Department of Behavioural Neuroscience, School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| | - Kirsten N. Abbott
- Department of Behavioural Neuroscience, School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| | - Christopher P. Antoniadis
- Department of Behavioural Neuroscience, School of Psychology, UNSW Sydney, Sydney, NSW, Australia
- Department of Medicine, School of Medicine, Griffith University, Gold Coast, QLD, Australia
| | - Angela Stuart
- Department of Behavioural Neuroscience, School of Psychology, UNSW Sydney, Sydney, NSW, Australia
- Department of Pharmacology, School of Medicine, UNSW Sydney, Sydney, NSW, Australia
| | - Denovan P. Begg
- Department of Behavioural Neuroscience, School of Psychology, UNSW Sydney, Sydney, NSW, Australia
| |
Collapse
|
11
|
Woods SC, May-Zhang AA, Begg DP. How and why do gastrointestinal peptides influence food intake? Physiol Behav 2018; 193:218-222. [PMID: 29577941 PMCID: PMC6087670 DOI: 10.1016/j.physbeh.2018.02.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/22/2018] [Accepted: 02/24/2018] [Indexed: 12/19/2022]
Abstract
Despite the ability of some gastrointestinal hormones to reliably reduce meal size when administered prior to a meal, it is not understood why the repeated administration or genetic knockout of these hormones appear largely ineffective in reducing food intake and body weight. Here, we review evidence that the ability of GI peptides such as cholecystokinin (CCK) to elicit satiation is a consequence of prior learning. Evidence includes first, that the ability of some of these signals to modify food intake depends upon past experience and is malleable with new experience. Additionally, the ability of CCK and other gut signals to reduce food intake may not be hard-wired; i.e., any so-called "satiation" signal that reduces food intake in a single-meal situation may not continue to do so over repeated trials. The individual will respond to the signal only so long as it provides reliable information about caloric content. If a particular signal becomes unreliable, the individual will rely on other signals to end meals. Thus, gut peptides/hormones have important metabolic effects such as mediating absorption, digestion, and many aspects of the distribution of ingested nutrients throughout the body; and, if they have been reliably associated with natural stimuli that mediate satiation, they also inform behavior.
Collapse
Affiliation(s)
- Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, United States.
| | - Aaron A May-Zhang
- Department of Medicine, Vanderbilt University, Nashville, TN, United States
| | | |
Collapse
|
12
|
Begg DP. Disturbances of thirst and fluid balance associated with aging. Physiol Behav 2017; 178:28-34. [DOI: 10.1016/j.physbeh.2017.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 02/22/2017] [Accepted: 03/02/2017] [Indexed: 01/25/2023]
|
13
|
Woods SC, May AA, Liu M, Tso P, Begg DP. Using the cerebrospinal fluid to understand ingestive behavior. Physiol Behav 2017; 178:172-178. [PMID: 27923718 PMCID: PMC5944842 DOI: 10.1016/j.physbeh.2016.11.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/22/2016] [Accepted: 11/28/2016] [Indexed: 01/08/2023]
Abstract
The cerebrospinal fluid (CSF) offers a window into the workings of the brain and blood-brain barrier (BBB). Molecules that enter into the central nervous system (CNS) by passive diffusion or receptor-mediated transport through the choroid plexus often appear in the CSF prior to acting within the brain. Other molecules enter the CNS by passing through the BBB into the brain's interstitial fluid prior to appearing in the CSF. This pattern is also often observed for molecules synthesized by neurons or glia within the CNS. The CSF is therefore an important conduit for the entry and clearance of molecules into/from the CNS and thereby constitutes an important window onto brain activity and barrier function. Assessing the CSF basally, under experimental conditions, or in the context of challenges or metabolic diseases can provide powerful insights about brain function. Here, we review important findings made by our labs, as influenced by the late Randall Sakai, by interrogating the CSF.
Collapse
Affiliation(s)
- Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - Aaron A May
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Min Liu
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Patrick Tso
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Denovan P Begg
- School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia
| |
Collapse
|
14
|
Abstract
Food intake occurs in bouts or meals, and numerous meal-generated signals have been identified that act to limit the size of ongoing meals. Hormones such as cholecystokinin (CCK) are secreted from the intestine as ingested food is being processed, and in addition to aiding the digestive process, they provide a signal to the brain that contributes to satiation, limiting the size of the meal. The potency of CCK to elicit satiation is enhanced by elevated levels of adiposity signals such as insulin. In the present experiments we asked whether CCK and insulin interact at the level of the blood-brain barrier (BBB). We first isolated rat brain capillary endothelial cells that comprise the BBB and found that they express the mRNA for both the CCK1R and the insulin receptor, providing a basis for a possible interaction. We then administered insulin intraperitoneally to another group of rats and 15min later administered CCK-8 intraperitoneally to half of those rats. After another 15min, CSF and blood samples were obtained and assayed for immunoreactive insulin. Plasma insulin was comparably elevated above baseline in both the CCK-8 and control groups, indicating that the CCK had no effect on circulating insulin levels given these parameters. In contrast, rats administered CCK had CSF-insulin levels that were more than twice as high as those of control rats. We conclude that circulating CCK greatly facilitates the transport of insulin into the brain, likely by acting directly at the BBB. These findings imply that in circumstances in which the plasma levels of both CCK and insulin are elevated, such as during and soon after meals, satiation is likely to be due, in part, to this newly-discovered synergy between CCK and insulin.
Collapse
Affiliation(s)
- Aaron A May
- University of Cincinnati College of Medicine, Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, OH, USA
| | - Min Liu
- University of Cincinnati College of Medicine, Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, OH, USA
| | - Stephen C Woods
- University of Cincinnati College of Medicine, Department of Psychiatry and Behavioral Neuroscience, Metabolic Diseases Institute, OH, USA.
| | - Denovan P Begg
- University of New South Wales, School of Psychology, Sydney, NSW 2052, Australia
| |
Collapse
|
15
|
Abstract
The ability of hormones such as insulin, leptin, and cholecystokinin to alter food intake is influenced by intricate interactions between homeostatic and non-homeostatic factors. Consequently, when administered exogenously, the likelihood of these hormones influencing food intake is probabilistic, leading to difficulties replicating previously reported outcomes both within and between labs.
Collapse
Affiliation(s)
- Stephen C Woods
- University of Cincinnati Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, 2170 Galbraith Avenue, Cincinnati, OH 45237, USA.
| | - Denovan P Begg
- University of New South Wales, School of Psychology, University of New South Wales (UNSW, Australia), Sydney, NSW 2052, Australia
| |
Collapse
|
16
|
Obici S, Magrisso IJ, Ghazarian AS, Shirazian A, Miller JR, Loyd CM, Begg DP, Krawczewski Carhuatanta KA, Haas MK, Davis JF, Woods SC, Sandoval DA, Seeley RJ, Goodyear LJ, Pothos EN, Mul JD. Moderate voluntary exercise attenuates the metabolic syndrome in melanocortin-4 receptor-deficient rats showing central dopaminergic dysregulation. Mol Metab 2015; 4:692-705. [PMID: 26500841 PMCID: PMC4588435 DOI: 10.1016/j.molmet.2015.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 07/07/2015] [Accepted: 07/09/2015] [Indexed: 01/12/2023] Open
Abstract
Objective Melanocortin-4 receptors (MC4Rs) are highly expressed by dopamine-secreting neurons of the mesolimbic tract, but their functional role has not been fully resolved. Voluntary wheel running (VWR) induces adaptations in the mesolimbic dopamine system and has a myriad of long-term beneficial effects on health. In the present experiments we asked whether MC4R function regulates the effects of VWR, and whether VWR ameliorates MC4R-associated symptoms of the metabolic syndrome. Methods Electrically evoked dopamine release was measured in slice preparations from sedentary wild-type and MC4R-deficient Mc4rK314X (HOM) rats. VWR was assessed in wild-type and HOM rats, and in MC4R-deficient loxTBMc4r mice, wild-type mice body weight-matched to loxTBMc4r mice, and wild-type mice with intracerebroventricular administration of the MC4R antagonist SHU9119. Mesolimbic dopamine system function (gene/protein expression) and metabolic parameters were examined in wheel-running and sedentary wild-type and HOM rats. Results Sedentary obese HOM rats had increased electrically evoked dopamine release in several ventral tegmental area (VTA) projection sites compared to wild-type controls. MC4R loss-of-function decreased VWR, and this was partially independent of body weight. HOM wheel-runners had attenuated markers of intracellular D1-type dopamine receptor signaling despite increased dopamine flux in the VTA. VWR increased and decreased ΔFosB levels in the nucleus accumbens (NAc) of wild-type and HOM runners, respectively. VWR improved metabolic parameters in wild-type wheel-runners. Finally, moderate voluntary exercise corrected many aspects of the metabolic syndrome in HOM runners. Conclusions Central dopamine dysregulation during VWR reinforces the link between MC4R function and molecular and behavioral responding to rewards. The data also suggest that exercise can be a successful lifestyle intervention in MC4R-haploinsufficient individuals despite reduced positive reinforcement during exercise training. MC4R-deficiency causes metabolic syndrome. Loss of MC4R signaling decreases voluntary wheel running (VWR). Despite moderate amounts of VWR, MC4R-associated metabolic syndrome is severely attenuated. MC4R-deficiency is associated with mesolimbic dopamine dysregulation during VWR.
Collapse
Affiliation(s)
- Silvana Obici
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - I Jack Magrisso
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Armen S Ghazarian
- Programs in Pharmacology and Experimental Therapeutics and Neuroscience, Sackler School of Graduate Biomedical Sciences and Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA
| | - Alireza Shirazian
- Programs in Pharmacology and Experimental Therapeutics and Neuroscience, Sackler School of Graduate Biomedical Sciences and Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA
| | - Jonas R Miller
- Programs in Pharmacology and Experimental Therapeutics and Neuroscience, Sackler School of Graduate Biomedical Sciences and Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA
| | - Christine M Loyd
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Denovan P Begg
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA ; School of Psychology, UNSW Australia, Sydney, NSW, Australia
| | | | - Michael K Haas
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Jon F Davis
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Stephen C Woods
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | - Darleen A Sandoval
- North Campus Research Complex, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Randy J Seeley
- North Campus Research Complex, Department of Surgery, University of Michigan, Ann Arbor, MI, USA
| | | | - Emmanuel N Pothos
- Programs in Pharmacology and Experimental Therapeutics and Neuroscience, Sackler School of Graduate Biomedical Sciences and Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA
| | - Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA ; Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
17
|
Begg DP, May AA, Mul JD, Liu M, D'Alessio DA, Seeley RJ, Woods SC. Insulin Detemir Is Transported From Blood to Cerebrospinal Fluid and Has Prolonged Central Anorectic Action Relative to NPH Insulin. Diabetes 2015; 64:2457-66. [PMID: 25667307 PMCID: PMC4477354 DOI: 10.2337/db14-1364] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 01/30/2015] [Indexed: 02/04/2023]
Abstract
Insulin detemir (DET) reduces glycemia comparably to other long-acting insulin formulations but causes less weight gain. Insulin signaling in the brain is catabolic, reducing food intake. We hypothesized that DET reduces weight gain, relative to other insulins, owing to increased transport into the central nervous system and/or increased catabolic action within the brain. Transport of DET and NPH insulin into the cerebrospinal fluid (CSF) was compared over several hours and after the administration of different doses peripherally in rats. DET and NPH had comparable saturable, receptor-mediated transport into the CSF. CSF insulin remained elevated significantly longer after intraperitoneal DET than after NPH. When administered acutely into the 3rd cerebral ventricle, both DET and NPH insulin reduced food intake and body weight at 24 h, and both food intake and body weight remained lower after DET than after NPH after 48 h. In direct comparison with another long-acting insulin, insulin glargine (GLAR), DET led to more prolonged increases in CSF insulin despite a shorter plasma half-life in both rats and mice. Additionally, peripheral DET administration reduced weight gain and increased CSF insulin compared with saline or GLAR in mice. Overall, these data support the hypothesis that DET has distinct effects on energy balance through enhanced and prolonged centrally mediated reduction of food intake.
Collapse
Affiliation(s)
- Denovan P Begg
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH School of Psychology, UNSW Australia, Sydney, NSW, Australia
| | - Aaron A May
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Min Liu
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - David A D'Alessio
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH Department of Medicine, Duke University, Durham, NC
| | - Randy J Seeley
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH Department of Surgery, University of Michigan, Ann Arbor, MI
| | - Stephen C Woods
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| |
Collapse
|
18
|
Abstract
The pancreatic hormone insulin plays a well-described role in the periphery, based principally on its ability to lower circulating glucose levels via activation of glucose transporters. However, insulin also acts within the central nervous system (CNS) to alter a number of physiological outcomes ranging from energy balance and glucose homeostasis to cognitive performance. Insulin is transported into the CNS by a saturable receptor-mediated process that is proposed to be dependent on the insulin receptor. Transport of insulin into the brain is dependent on numerous factors including diet, glycemia, a diabetic state and notably, obesity. Obesity leads to a marked decrease in insulin transport from the periphery into the CNS and the biological basis of this reduction of transport remains unresolved. Despite decades of research into the effects of central insulin on a wide range of physiological functions and its transport from the periphery to the CNS, numerous questions remain unanswered including which receptor is responsible for transport and the precise mechanisms of action of insulin within the brain.
Collapse
Affiliation(s)
- Denovan P Begg
- School of Psychology, University of New South Wales (UNSW, Australia), Sydney, New South Wales, Australia.
| |
Collapse
|
19
|
Mul JD, Begg DP, Haller AM, Pressler JW, Sorrell J, Woods SC, Farese RV, Seeley RJ, Sandoval DA. MGAT2 deficiency and vertical sleeve gastrectomy have independent metabolic effects in the mouse. Am J Physiol Endocrinol Metab 2014; 307:E1065-72. [PMID: 25315695 PMCID: PMC4254982 DOI: 10.1152/ajpendo.00376.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Vertical sleeve gastrectomy (VSG) is currently one of the most effective treatments for obesity. Despite recent developments, the underlying mechanisms that contribute to the metabolic improvements following bariatric surgery remain unresolved. VSG reduces postprandial intestinal triglyceride (TG) production, but whether the effects of VSG on intestinal metabolism are related to metabolic outcomes has yet to be established. The lipid synthesis enzyme acyl CoA:monoacylglycerol acyltransferase-2 (Mogat2; MGAT2) plays a crucial role in the assimilation of dietary fat in the intestine and in regulation of adiposity stores as well. Given the phenotypic similarities between VSG-operated and MGAT2-deficient animals, we reasoned that this enzyme could also have a key role in mediating the metabolic benefits of VSG. However, VSG reduced body weight and fat mass and improved glucose metabolism similarly in whole body MGAT2-deficient (Mogat2(-/-)) mice and wild-type littermates. Furthermore, along with an increase in energy expenditure, surgically naive Mogat2(-/-) mice had altered macronutrient preference, shifting preference away from fat and toward carbohydrates, and increased locomotor activity. Collectively, these data suggest that the beneficial effects of VSG on body weight and glucose metabolism are independent of MGAT2 activity and rather that they are separate from the effects of MGAT2 deficiency. Because MGAT2 inhibitors are proposed as a pharmacotherapeutic option for obesity, our data suggest that, in addition to increasing energy expenditure, shifting macronutrient preference away from fat could be another important mechanism by which these compounds could contribute to weight loss.
Collapse
Affiliation(s)
- Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
| | - Denovan P Begg
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio; School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - April M Haller
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
| | - Josh W Pressler
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
| | - Joyce Sorrell
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
| | - Stephen C Woods
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio
| | - Robert V Farese
- Gladstone Institute of Cardiovascular Disease, San Francisco, California; Departments of Medicine, Biochemistry, and Biophysics, University of California, San Francisco, California; and
| | - Randy J Seeley
- North Campus Research Complex, Department of Surgery, University of Michigan, Ann Arbor, Michigan
| | - Darleen A Sandoval
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio;
| |
Collapse
|
20
|
Abstract
Uroguanylin is a gastrointestinal hormone primarily involved in fluid and electrolyte handling. It has recently been reported that prouroguanylin, secreted postprandially, is converted to uroguanylin in the brain and activates the receptor guanylate cyclase-C (GC-C) to reduce food intake and prevent obesity. We tested central nervous system administration of two GC-C agonists and found no significant reduction of food intake. We also carefully phenotyped mice lacking the GC-C receptor and found them to have normal body weight, adiposity, and glucose tolerance. Interestingly, uroguanylin knockout mice had a small but significant increase in body weight and adiposity that was accompanied by glucose intolerance. Our data indicate that the modest effects of uroguanylin on energy and glucose homeostasis are not mediated by central GC-C receptors.
Collapse
Affiliation(s)
- Denovan P Begg
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH School of Psychology, University of New South Wales, Sydney, New South Wales, Australia
| | - Kris A Steinbrecher
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - Adam P Chambers
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - Rohit Kohli
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - April Haller
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - Mitchell B Cohen
- Division of Gastroenterology, Hepatology, and Nutrition, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
| | - Stephen C Woods
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| | - Randy J Seeley
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH
| |
Collapse
|
21
|
Ryan KK, Mul JD, Clemmensen C, Egan AE, Begg DP, Halcomb K, Seeley RJ, Herman JP, Ulrich-Lai YM. Loss of melanocortin-4 receptor function attenuates HPA responses to psychological stress. Psychoneuroendocrinology 2014; 42:98-105. [PMID: 24636506 PMCID: PMC4120841 DOI: 10.1016/j.psyneuen.2014.01.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/12/2014] [Accepted: 01/13/2014] [Indexed: 12/27/2022]
Abstract
The melanocortin 4 receptor (MC4R), well-known for its role in the regulation of energy balance, is widely expressed in stress-regulatory brain regions, including the paraventricular nucleus of the hypothalamus (PVH) and the medial amygdala (MeA). In agreement with this, MC4R has been implicated in hypothalamic-pituitary-adrenocortical axis (HPA) regulation. The present work investigated the role of chronic Mc4r function to modulate basal HPA axis tone and to facilitate acute HPA responses to psychological stress, using a novel rat model with Mc4r loss-of-function. In this study, adult male rats were placed into 3 groups (n=15/group) according to genotype [wild-type (WT); heterozygous mutant (HET); and homozygous mutant (HOM)]. Basal (pre-stress) plasma adrenocorticotropic hormone (ACTH) and corticosterone were measured in the AM and PM, and the HPA axis response to restraint was assessed in the AM. Rats were perfused at 2h after restraint to assess the effect of loss of MC4R on stress-induced c-Fos immunolabeling in stress-regulatory brain regions. We find that basal (non-stress) AM and PM plasma ACTH and corticosterone showed a normal diurnal rhythm that was not altered according to genotype. Consistent with this, adrenal and thymus weights were unaffected by genotype. However, the plasma ACTH and corticosterone responses to restraint were significantly reduced by loss of MC4R function. Likewise, stress-induced c-Fos immunolabeling in both PVH and MeA was significantly reduced by loss of Mc4r function. These results support the hypothesis that endogenous MC4R signaling contributes to the HPA axis response to stress. Because MC4R plays a critical role in the regulation of energy balance, the present work suggests that it may also serve as an important communication link between brain metabolic and stress systems.
Collapse
Affiliation(s)
- Karen K. Ryan
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati, Cincinnati OH, USA
| | - Joram D. Mul
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati, Cincinnati OH, USA
| | - Christoffer Clemmensen
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati, Cincinnati OH, USA,Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Ann E. Egan
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati OH, USA
| | - Denovan P. Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati OH, USA
| | - Kristen Halcomb
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati OH, USA
| | - Randy J. Seeley
- Department of Internal Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati, Cincinnati OH, USA
| | - James P. Herman
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati OH, USA
| | - Yvonne M. Ulrich-Lai
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati OH, USA
| |
Collapse
|
22
|
Hafandi A, Begg DP, Premaratna SD, Sinclair AJ, Jois M, Weisinger RS. Dietary repletion with ω3 fatty acid or with COX inhibition reverses cognitive effects in F3 ω3 fatty-acid-deficient mice. Comp Med 2014; 64:106-109. [PMID: 24674584 PMCID: PMC3997287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/12/2013] [Accepted: 10/24/2013] [Indexed: 06/03/2023]
Abstract
Dietary deficiency of ω3 fatty acid during development leads to impaired cognitive function. However, the effects of multiple generations of ω3 fatty-acid deficiency on cognitive impairment remain unclear. In addition, we sought to test the hypothesis that the cognitive impairments of ω3 fatty-acid-deficient mice are mediated through the arachidonic acid-cyclooxygenase (COX) pathway. To address these issues, C57BL/6J mice were bred for 3 generations and fed diets either deficient (DEF) or sufficient (SUF) in ω3 fatty acids. At postnatal day 21, the F3 offspring remained on the dam's diet or were switched to the opposite diet, creating 4 groups. In addition, 2 groups that remained on the dam's diet were treated with a COX inhibitor. At 19 wk of age, spatial-recognition memory was tested on a Y-maze. Results showed that 16 wk of SUF diet reversed the cognitive impairment of F3 DEF mice. However, 16 wk of ω3 fatty-acid-deficient diet impaired the cognitive performance of the F3 SUF mice, which did not differ from that of the F3 DEF mice. These findings suggest that the cognitive deficits after multigenerational maintenance on ω3 fatty-acid-deficient diet are not any greater than are those after deficiency during a single generation. In addition, treatment with a COX inhibitor prevented spatial-recognition deficits in F3 DEF mice. Therefore, cognitive impairment due to dietary ω3 fatty-acid deficiency appears to be mediated by the arachidonic acid-COX pathway and can be prevented by 16 wk of dietary repletion with ω3 fatty acids or COX inhibition.
Collapse
Affiliation(s)
- Ahmad Hafandi
- School of Psychological Science, La Trobe University, Victoria, Australia; Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, University Putra Malaysia, Serdang, Selangor Malaysia.
| | - Denovan P Begg
- School of Psychological Science, School of Exercise and Nutrition Sciences, Deakin University, Victoria, Australia
| | | | - Andrew J Sinclair
- School of Exercise and Nutrition Sciences, Deakin University, Victoria, Australia
| | - Mark Jois
- School of Life Sciences, La Trobe University, Victoria, Australia
| | | |
Collapse
|
23
|
Chambers AP, Smith EP, Begg DP, Grayson BE, Sisley S, Greer T, Sorrell J, Lemmen L, LaSance K, Woods SC, Seeley RJ, D'Alessio DA, Sandoval DA. Regulation of gastric emptying rate and its role in nutrient-induced GLP-1 secretion in rats after vertical sleeve gastrectomy. Am J Physiol Endocrinol Metab 2014; 306:E424-32. [PMID: 24368666 PMCID: PMC3923088 DOI: 10.1152/ajpendo.00469.2013] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) are effective weight loss surgeries that also improve glucose metabolism. Rapid, early rises of circulating insulin and glucagon-like peptide-1 (GLP-1) concentrations following food ingestion are characteristic of these procedures. The purpose of the current study was to test the hypothesis that postprandial hormone release is due to increased nutrient emptying from the stomach. Radioscintigraphy and chemical and radiolabeled tracers were used to examine gastric emptying in rat models of VSG and RYGB surgery. Intraduodenal nutrient infusions were used to assess intestinal GLP-1 secretion and nutrient sensitivity in VSG rats compared with shams. Five minutes after a nutrient gavage, the stomachs of RYGB and VSG rats were completely emptied, whereas only 6.1% of the nutrient mixture had emptied from sham animals. Gastric pressure was increased in VSG animals, and rats with this procedure did not inhibit gastric emptying normally in response to increasing caloric loads of dextrose or corn oil, and they did not respond to neural or endocrine effectors of gastric motility. Finally, direct infusion of liquid nutrients into the duodenum caused significantly greater GLP-1 release in VSG compared with shams, indicating that increases in GLP-1 secretion after VSG are the result of both greater gastric emptying rates and altered responses at the level of the intestine. These findings demonstrate greatly accelerated gastric emptying in rat models of RYGB and VSG. In VSG this is likely due to increased gastric pressure and reduced responses to inhibitory feedback from the intestine.
Collapse
Affiliation(s)
- Adam P Chambers
- Division of Endocrinology and Metabolism, University of Cincinnati, Cincinnati, Ohio
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
Ingestion of fatty foods increases dopamine release in the substantia nigra, producing a positive hedonic state. Tellez et al. (2013) demonstrate that an intestinal signal generated by fat consumption, oleoylethanolamide, stimulates central dopamine activity, thus regulating the reward value of fat and establishing a link between caloric-homeostatic and hedonic-homeostatic controllers.
Collapse
Affiliation(s)
- Denovan P Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA
| | | |
Collapse
|
25
|
Abstract
Many questions must be considered with regard to consuming food, including when to eat, what to eat and how much to eat. Although eating is often thought to be a homeostatic behaviour, little evidence exists to suggest that eating is an automatic response to an acute shortage of energy. Instead, food intake can be considered as an integrated response over a prolonged period of time that maintains the levels of energy stored in adipocytes. When we eat is generally determined by habit, convenience or opportunity rather than need, and meals are preceded by a neurally-controlled coordinated secretion of numerous hormones that prime the digestive system for the anticipated caloric load. How much we eat is determined by satiation hormones that are secreted in response to ingested nutrients, and these signals are in turn modified by adiposity hormones that indicate the fat content of the body. In addition, many nonhomeostatic factors, including stress, learning, palatability and social influences, interact with other controllers of food intake. If a choice of food is available, what we eat is based on pleasure and past experience. This article reviews the hormones that mediate and influence these processes.
Collapse
Affiliation(s)
- Denovan P Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, 2170 East Galbraith Road, Cincinnati, OH 45237, USA
| | | |
Collapse
|
26
|
Stemmer K, Bielohuby M, Grayson BE, Begg DP, Chambers AP, Neff C, Woods SC, Erben RG, Tschöp MH, Bidlingmaier M, Clemens TL, Seeley RJ. Roux-en-Y gastric bypass surgery but not vertical sleeve gastrectomy decreases bone mass in male rats. Endocrinology 2013; 154:2015-24. [PMID: 23554454 PMCID: PMC5393329 DOI: 10.1210/en.2012-2130] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The most effective treatment for obesity is bariatric surgery. However, there is increasing concern that bariatric surgery can cause nutrient deficiencies that translate into metabolic bone disease. Whether this is true for all surgery types is not yet clear. We therefore investigated the effects of 2 commonly applied bariatric surgeries (Roux-en-Y gastric bypass [RYGB] and vertical sleeve gastrectomy) on energy and bone metabolism in rats 60 days after surgery. Both surgeries resulted in similar reductions of body weight, body fat, and food intake. Glucose tolerance was improved to a similar extent after both surgeries and was accompanied by increased postprandial secretion of glucose-dependent insulinotropic peptide. Using microcomputed tomography, we found that, relative to sham-operated rats, bone volume was significantly reduced after RYGB but not vertical sleeve gastrectomy. RYGB rats also had markedly reduced lipid absorption from the intestine and significantly lower serum 25-hydroxyvitamin D and calcium levels. Importantly, dietary supplementation with calcium and vitamin D could not fully rescue the reduced bone volume after RYGB surgery. Both surgeries resulted in a significant increase in stomach pH, which may have worsened the malabsorption in RYGB rats. Our findings suggest that bone loss in RYGB rats is not exclusively driven by calcium and vitamin D malabsorption but also by additional factors that may not be rescuable by dietary supplementation. These data point toward important similarities and differences between bariatric procedures that should be considered in clinical settings as guidance for which procedure will be best for specific patient populations.
Collapse
Affiliation(s)
- Kerstin Stemmer
- Institute for Diabetes and Obesity, Helmholtz Centre Munich, 85764 Neuherberg, Germany. Department of Orthopaedic Surgery (T.L.C.), The Johns Hopkins University, Baltimore, Maryland 21287 and the Baltimore Veterans Affairs Medical Center (T.L.C.), Baltimore, Maryland 21201
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Mul JD, Begg DP, Barrera JG, Li B, Matter EK, D'Alessio DA, Woods SC, Seeley RJ, Sandoval DA. High-fat diet changes the temporal profile of GLP-1 receptor-mediated hypophagia in rats. Am J Physiol Regul Integr Comp Physiol 2013; 305:R68-77. [PMID: 23616105 DOI: 10.1152/ajpregu.00588.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Overconsumption of a high-fat diet promotes weight gain that can result in obesity and associated comorbidities, including Type 2 diabetes mellitus. Consumption of a high-fat diet also alters gut-brain communication. Glucagon-like peptide 1 (GLP-1) is an important gastrointestinal signal that modulates both short- and long-term energy balance and is integral in maintenance of glucose homeostasis. In the current study, we investigated whether high-fat diets (40% or 81% kcal from fat) modulated the ability of the GLP-1 receptor (GLP-1r) agonists exendin-4 (Ex4) and liraglutide to reduce food intake and body weight. We observed that rats maintained on high-fat diets had a delayed acute anorexic response to peripheral administration of Ex4 or liraglutide compared with low-fat diet-fed rats (17% kcal from fat). However, once suppression of food intake in response to Ex4 or liraglutide started, the effect persisted for a longer time in the high-fat diet-fed rats compared with low-fat diet-fed rats. In contrast, centrally administered Ex4 suppressed food intake similarly between high-fat diet-fed and low-fat diet-fed rats. Chronic consumption of a high-fat diet did not change the pharmacokinetics of Ex4 but increased intestinal Glp1r expression and decreased hindbrain Glp1r expression. Taken together, these findings demonstrate that dietary composition alters the temporal profile of the anorectic response to exogenous GLP-1r agonists.
Collapse
Affiliation(s)
- Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH 45327, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Begg DP, Mul JD, Liu M, Reedy BM, D'Alessio DA, Seeley RJ, Woods SC. Reversal of diet-induced obesity increases insulin transport into cerebrospinal fluid and restores sensitivity to the anorexic action of central insulin in male rats. Endocrinology 2013; 154:1047-54. [PMID: 23337529 PMCID: PMC3578991 DOI: 10.1210/en.2012-1929] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Diet-induced obesity (DIO) reduces the ability of centrally administered insulin to reduce feeding behavior and also reduces the transport of insulin from the periphery to the central nervous system (CNS). The current study was designed to determine whether reversal of high-fat DIO restores the anorexic efficacy of central insulin and whether this is accompanied by restoration of the compromised insulin transport. Adult male Long-Evans rats were initially maintained on either a low-fat chow diet (LFD) or a high-fat diet (HFD). After 22 weeks, half of the animals on the HFD were changed to the LFD, whereas the other half continued on the HFD for an additional 8 weeks, such that there were 3 groups: 1) a LFD control group (Con; n = 18), 2) a HFD-fed, DIO group (n = 17), and 3) a HFD to LFD, DIO-reversal group (DIO-rev; n = 18). The DIO reversal resulted in a significant reduction of body weight and epididymal fat weight relative to the DIO group. Acute central insulin administration (8 mU) reduced food intake and caused weight loss in Con and DIO-rev but not DIO rats. Fasting cerebrospinal fluid insulin was higher in DIO than Con animals. However, after a peripheral bolus injection of insulin, cerebrospinal fluid insulin increased in Con and DIO-rev rats but not in the DIO group. These data provide support for previous reports that DIO inhibits both the central effects of insulin and insulin's transport to the CNS. Importantly, DIO-rev restored sensitivity to the effects of central insulin on food intake and insulin transport into the CNS.
Collapse
Affiliation(s)
- Denovan P Begg
- Departments of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA.
| | | | | | | | | | | | | |
Collapse
|
29
|
Begg DP, Woods SC. Interactions between the central nervous system and pancreatic islet secretions: a historical perspective. Adv Physiol Educ 2013; 37:53-60. [PMID: 23471249 PMCID: PMC3776474 DOI: 10.1152/advan.00167.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 01/14/2013] [Indexed: 05/10/2023]
Abstract
The endocrine pancreas is richly innervated with sympathetic and parasympathetic projections from the brain. In the mid-20th century, it was established that α-adrenergic activation inhibits, whereas cholinergic stimulation promotes, insulin secretion; this demonstrated the importance of the sympathetic and parasympathetic systems in pancreatic endocrine function. It was later established that insulin injected peripherally could act within the brain, leading to the discovery of insulin and insulin receptors within the brain and the receptor-mediated transport of insulin into the central nervous system from endothelial cells. The insulin receptor within the central nervous system is widely distributed, reflecting insulin's diverse range of actions, including acting as an adiposity signal to reduce food intake and increase energy expenditure, regulation of systemic glucose responses, altering sympathetic activity, and involvement in cognitive function. As observed with central insulin administration, the pancreatic hormones glucagon, somatostatin, pancreatic polypeptide, and amylin can each also reduce food intake. Pancreatic and also gut hormones are released cephalically, in what is an important mechanism to prepare the body for a meal and prevent excessive postprandial hyperglycemia.
Collapse
Affiliation(s)
- Denovan P Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA
| | | |
Collapse
|
30
|
Mul JD, Begg DP, Alsters SIM, van Haaften G, Duran KJ, D'Alessio DA, le Roux CW, Woods SC, Sandoval DA, Blakemore AIF, Cuppen E, van Haelst MM, Seeley RJ. Effect of vertical sleeve gastrectomy in melanocortin receptor 4-deficient rats. Am J Physiol Endocrinol Metab 2012; 303:E103-10. [PMID: 22535749 PMCID: PMC3404562 DOI: 10.1152/ajpendo.00159.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Bariatric surgery is currently the most effective treatment for obesity. Vertical sleeve gastrectomy (VSG), a commonly applied bariatric procedure, involves surgically incising most of the volume of the stomach. In humans, partial loss of melanocortin receptor-4 (MC4R) activity is the most common monogenic correlate of obesity regardless of lifestyle. At present it is unclear whether genetic alteration of MC4R signaling modulates the beneficial effects of VSG. Following VSG, we analyzed body weight, food intake, glucose sensitivity, and macronutrient preference of wild-type and MC4R-deficient (Mc4r(+/-) and Mc4r(-/-)) rats compared with sham-operated controls. VSG reduced body weight and fat mass and improved glucose metabolism and also shifted preference toward carbohydrates and away from fat. All of this occurred independently of MC4R activity. In addition, MC4R was resequenced in 46 human subjects who underwent VSG. We observed common genetic variations in the coding sequence of MC4R in five subjects. However, none of those variations appeared to affect the outcome of VSG. Taken together, these data suggest that the beneficial effect of VSG on body weight and glucose metabolism is not mediated by alterations in MC4R activity.
Collapse
Affiliation(s)
- Joram D Mul
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, OH, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Yoshimichi G, Lo CC, Tamashiro KLK, Ma L, Lee DM, Begg DP, Liu M, Sakai RR, Woods SC, Yoshimatsu H, Tso P. Effect of peripheral administration of cholecystokinin on food intake in apolipoprotein AIV knockout mice. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1336-42. [PMID: 22461023 PMCID: PMC3378168 DOI: 10.1152/ajpgi.00325.2010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Apolipoprotein AIV (apo AIV) and cholecystokinin (CCK) are satiation factors secreted by the small intestine in response to lipid meals. Apo AIV and CCK-8 has an additive effect to suppress food intake relative to apo AIV or CCK-8 alone. In this study, we determined whether CCK-8 (1, 3, or 5 μg/kg ip) reduces food intake in fasted apo AIV knockout (KO) mice as effectively as in fasted wild-type (WT) mice. Food intake was monitored by the DietMax food system. Apo AIV KO mice had significantly reduced 30-min food intake following all doses of CCK-8, whereas WT mice had reduced food intake only at doses of 3 μg/kg and above. Post hoc analysis revealed that the reduction of 10-min and 30-min food intake elicited by each dose of CCK-8 was significantly larger in the apo AIV KO mice than in the WT mice. Peripheral CCK 1 receptor (CCK1R) gene expression (mRNA) in the duodenum and gallbladder of the fasted apo AIV KO mice was comparable to that in WT mice. In contrast, CCK1R mRNA in nodose ganglia of the apo AIV KO mice was upregulated relative to WT animals. Similarly, upregulated CCK1R gene expression was found in the brain stem of apo AIV KO mice by in situ hybridization. Although it is possible that the increased satiating potency of CCK in apo AIV KO mice is mediated by upregulation of CCK 1R in the nodose ganglia and nucleus tractus solitarius, additional experiments are required to confirm such a mechanism.
Collapse
Affiliation(s)
- Go Yoshimichi
- 1Department of Pathology and Laboratory Medicine and
| | - Chunmin C. Lo
- 1Department of Pathology and Laboratory Medicine and
| | | | - Liyun Ma
- 2Psychiatry, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio;
| | - Dana M. Lee
- 1Department of Pathology and Laboratory Medicine and
| | - Denovan P. Begg
- 2Psychiatry, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio;
| | - Min Liu
- 1Department of Pathology and Laboratory Medicine and
| | - Randall R. Sakai
- 2Psychiatry, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio;
| | - Stephen C. Woods
- 2Psychiatry, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio;
| | | | - Patrick Tso
- 1Department of Pathology and Laboratory Medicine and
| |
Collapse
|
32
|
Abstract
Insulin acts throughout the body to reduce circulating energy and to increase energy storage. Within the brain, insulin produces a net catabolic effect by reducing food intake and increasing energy expenditure; this is evidenced by the hypophagia and increased brown adipose tissue sympathetic nerve activity induced by central insulin infusion. Reducing the activity of the brain insulin system via administration of insulin antibodies, receptor antisense treatment, or receptor knockdown results in hyperphagia and increased adiposity. However, despite decades of research into the role of central insulin in food intake, many questions remain to be answered, including the underlying mechanism of action.
Collapse
Affiliation(s)
- Denovan P Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, OH 45237, USA
| | | |
Collapse
|
33
|
Begg DP, Puskás LG, Kitajka K, Ménesi D, Allen AM, Li D, Mathai ML, Shi JR, Sinclair AJ, Weisinger RS. Hypothalamic gene expression in ω-3 PUFA-deficient male rats before, and following, development of hypertension. Hypertens Res 2011; 35:381-7. [PMID: 22072108 DOI: 10.1038/hr.2011.194] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Dietary deficiency of ω-3 fatty acids (ω-3 DEF) produces hypertension in later life. This study examined the effect of ω-3 DEF on blood pressure and hypothalamic gene expression in young rats, before the development of hypertension, and in older rats following the onset of hypertension. Animals were fed experimental diets that were deficient in ω-3 fatty acids, sufficient in short-chain ω-3 fatty acids or sufficient in short- and long-chain ω-3 fatty acids, from the prenatal period until 10 or 36 weeks-of-age. There was no difference in blood pressure between groups at 10 weeks-of-age; however, at 36 weeks-of-age ω-3 DEF animals were hypertensive in relation to sufficient groups. At 10 weeks, expression of angiotensin-II(1A) receptors and dopamine D(3) receptors were significantly increased in the hypothalamic tissue of ω-3 DEF animals. In contrast, at 36 weeks, α(2a) and β(1) adrenergic receptor expression was significantly reduced in the ω-3 DEF group. Brain docosahexaenoic acid was significantly lower in ω-3 DEF group compared with sufficient groups. This study demonstrates that dietary ω-3 DEF causes changes both in the expression of key genes involved in central blood pressure regulation and in blood pressure. The data may indicate that hypertension resulting from ω-3 DEF is mediated by the central adrenergic system.
Collapse
Affiliation(s)
- Denovan P Begg
- School of Medicine, Deakin University, Geelong, Victoria, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Premaratna SD, Manickam E, Begg DP, Rayment DJ, Hafandi A, Jois M, Cameron-Smith D, Weisinger RS. Angiotensin-converting enzyme inhibition reverses diet-induced obesity, insulin resistance and inflammation in C57BL/6J mice. Int J Obes (Lond) 2011; 36:233-43. [PMID: 21556046 DOI: 10.1038/ijo.2011.95] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AIM Angiotensin-converting enzyme (ACE) inhibition can reduce the body weight of mice maintained on a high-fat diet. The current study examined the effect of the ACE inhibitor, captopril (CAP), on the reversal of diet-induced obesity (DIO), insulin resistance and inflammation in mice. MATERIALS AND METHODS DIO was produced in C57BL/6J male mice (n=30) by maintaining animals on a high-fat diet (w/w 21% fat) for 12 weeks. During the subsequent 12-week treatment period, the animals were allowed access to the high-fat diet and either water containing CAP (0.05 mg ml(-1)) or plain tap water (CON, control). RESULTS From the first week of treatment, food intake and body weight decreased in CAP-treated mice compared with CON mice. Both peripheral insulin sensitivity and hepatic insulin sensitivity were improved in CAP-treated mice compared with CON mice. CAP-treated mice had decreased absolute and relative liver and epididymal fat weights compared with CON mice. CAP-treated mice had higher plasma adiponectin and lower plasma leptin levels than CON mice. Relative to CON mice, CAP-treated mice had reduced adipose and skeletal muscle monocyte chemoattractant protein 1 (MCP-1), adipose interleukin-6 (IL-6), toll-like receptor 4 (TLR4) and uncoupling protein 2 (UCP2) mRNA expressions. Furthermore, CAP-treated mice had increased peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), long chain acyl-CoA dehydrogenase (LCAD), hormone sensitive lipase (HSL) and decreased lipoprotein lipase (LPL) mRNA expressions in the liver. CONCLUSION The results of the current study indicate that in mice with DIO, CAP treatment reduced food intake and body weight, improved insulin sensitivity and decreased the mRNA expression of markers of inflammation. Thus, CAP may be a viable treatment for obesity, insulin resistance and inflammation.
Collapse
Affiliation(s)
- S D Premaratna
- School of Psychological Science, La Trobe University, Bundoora, Victoria, Australia
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Hallam KT, Begg DP, Olver JS, Norman TR. Abnormal dose-response melatonin suppression by light in bipolar type I patients compared with healthy adult subjects. Acta Neuropsychiatr 2009; 21:246-55. [PMID: 26952772 DOI: 10.1111/j.1601-5215.2009.00416.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE Among potential endophenotypes proposed for bipolar affective disorder focusing on circadian abnormalities associated with the illness has particularly high face validity. Melatonin sensitivity to light is one circadian endophenotype proposed as useful in bipolar disorder. The aim of this study was to investigate melatonin sensitivity to light over a range of light intensities in order to compare and contrast responses in bipolar I patients with those of healthy adult volunteers. METHODS The study included seven patients (4 females, 3 males) with bipolar I disorder and 34 control participants (22 females, 12 males) with no personal or family history of affective illness. Melatonin sensitivity to light was determined in all patients and participants across a range of light intensities (0, 200, 500 and 1000 lux). RESULTS The results indicated that patients showed melatonin super-sensitivity to light in comparison with controls, a response that was consistent across the entire light intensity range investigated. CONCLUSION The study provides further evidence for a super sensitive response in bipolar I patients and suggests that its potential usefulness as an endophenotypic marker of the illness is deserving of further research.
Collapse
Affiliation(s)
- Karen T Hallam
- 1Department of Psychiatry, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia
| | - Denovan P Begg
- 1Department of Psychiatry, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia
| | - James S Olver
- 1Department of Psychiatry, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia
| | - Trevor R Norman
- 1Department of Psychiatry, University of Melbourne, Austin Hospital, Heidelberg, Victoria, Australia
| |
Collapse
|
36
|
Weisinger RS, Begg DP, Jois M. Antagonists of the renin-angiotensin system and the prevention of obesity. Curr Opin Investig Drugs 2009; 10:1069-1077. [PMID: 19777395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In addition to its role as an energy store, adipose tissue also acts as an endocrine organ, synthesizing and secreting hormones and cytokines. This review discusses angiotensin II (Ang-II), the biologically active component of the renin-angiotensin system (RAS). Evidence suggests that a functioning RAS is present in adipose tissue. Animal studies have demonstrated that modifying the amount of Ang-II in the body (eg, using RAS knockout/transgenic animal models or the pharmacological treatment of animal models to prevent the formation or action of Ang-II) directly influences body weight and adiposity. In humans, body fat is correlated with levels of angiotensinogen, a precursor of Ang-II. Thus, the treatment of obesity could be improved through the use of substances that interfere with Ang-II.
Collapse
Affiliation(s)
- Richard S Weisinger
- La Trobe University, School of Psychological Science, Bundoora, Victoria 3086, Australia.
| | | | | |
Collapse
|
37
|
Weisinger RS, Stanley TK, Begg DP, Weisinger HS, Spark KJ, Jois M. Angiotensin converting enzyme inhibition lowers body weight and improves glucose tolerance in C57BL/6J mice maintained on a high fat diet. Physiol Behav 2009; 98:192-7. [DOI: 10.1016/j.physbeh.2009.05.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Revised: 04/23/2009] [Accepted: 05/15/2009] [Indexed: 01/14/2023]
|
38
|
Begg DP, Mathai ML, McKinley MJ, Frappell PB, Kent S. Central nitric oxide synthase inhibition restores behaviorally mediated lipopolysaccharide induced fever in near-term rats. Physiol Behav 2008; 94:630-4. [DOI: 10.1016/j.physbeh.2008.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2007] [Revised: 03/28/2008] [Accepted: 03/31/2008] [Indexed: 01/22/2023]
|
39
|
Hallam KT, Begg DP, Olver JS, Norman TR. An investigation of the effect of immediate and extended release venlafaxine on nocturnal melatonin and cortisol release in healthy adult volunteers. Hum Psychopharmacol 2008; 23:129-37. [PMID: 18172907 DOI: 10.1002/hup.913] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The secretion of the hormone melatonin is particularly robust to the effect of pharmacological agents. Medications may alter melatonin levels through either altering adrenergic activity or affecting liver enzymes involved in melatonin metabolism. The aim of this study was to investigate the effect of venlafaxine, a third generation antidepressant with known adrenergic properties on melatonin secretion. A further aim of the study was to investigate the correlation between plasma and salivary measures on this medication. Eight healthy adult participants (four males, four females) took part in this double blind placebo controlled randomised trial. Participants were tested on 3 nights after taking venlafaxine XR (75 mg), venlafaxine IR (75 mg) or placebo. Participants were placed in a darkened room between 1900 and 0300 h and regular temperature readings, blood and saliva samples were drawn to assess melatonin and cortisol secretion in each condition. There was no significant effect of venlafaxine IR or XR on melatonin concentrations in plasma or saliva and no effects on other circadian parameters including cortisol and temperature. It was notable that the correlation between plasma and salivary melatonin levels became poor after drug treatment. These results indicate that at low doses the mixed serotonergic and noradrenergic drug venlafaxine has no effect on nocturnal melatonin concentrations.
Collapse
Affiliation(s)
- Karen T Hallam
- Department of Psychiatry (Austin Health), The University of Melbourne, Australia.
| | | | | | | |
Collapse
|
40
|
Stahl LA, Begg DP, Weisinger RS, Sinclair AJ. The role of omega-3 fatty acids in mood disorders. Curr Opin Investig Drugs 2008; 9:57-64. [PMID: 18183532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Research has established that docosahexaenoic acid (DHA), a long-chain omega-3 polyunsaturated fatty acid (PUFA), plays a fundamental role in brain structure and function. Epidemiological and cross-sectional studies have also identified a role for long-chain omega-3 PUFA, which includes DHA, eicosapentaenoic acid, and docosapentaenoic acid, in the etiology of depression. In the past ten years, there have been 12 intervention studies conducted using various preparations of longchain omega-3 PUFA in unipolar and bipolar depression. The majority of these studies administered long-chain omega-3 PUFA as an adjunct therapy. The studies have been conducted over 4 to 16 weeks of intervention and have often included small cohorts. In four out of the seven studies conducted in depressed individuals and in two out of the five studies in bipolar patients, individuals have reported a positive outcome following supplementation with ethyl-eicosapentaenoic acid or fish oil containing long-chain omega-3 PUFA. In the three trials that researched the influence of DHA-rich preparations, no significant effects were reported. The mechanisms that have been invoked to account for the benefits of long-chain omega-3 PUFA in depression include reductions in prostaglandins derived from arachidonic acid, which lead to decreased brain-derived neurotrophic factor levels and/or alterations in blood flow to the brain.
Collapse
Affiliation(s)
- Lauren A Stahl
- La Trobe University, School of Psychological Science, Bundoora, VIC, Australia
| | | | | | | |
Collapse
|
41
|
Jayasooriya AP, Begg DP, Chen N, Mathai ML, Sinclair AJ, Wilkinson-Berka J, Wark JD, Weisinger HS, Weisinger RS. Omega-3 polyunsaturated fatty acid supplementation reduces hypertension in TGR(mRen-2)27 rats. Prostaglandins Leukot Essent Fatty Acids 2008; 78:67-72. [PMID: 18083506 DOI: 10.1016/j.plefa.2007.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 10/26/2007] [Accepted: 11/13/2007] [Indexed: 11/15/2022]
Abstract
To establish the effect of dietary omega-3 PUFA on angiotensin II (ANG II)-mediated hypertension, male TGR (mRen-2)27 (Ren-2) rats (animals with high ANG II activity) were maintained on a diet either deficient or sufficient in omega-3 PUFA from conception. Half the animals on each diet were treated with the angiotensin-converting enzyme inhibitor, perindopril, from birth. Ren-2 rats fed the omega-3 PUFA deficient diet were significantly more hypertensive than those fed the omega-3 PUFA sufficient diet. Perindopril reduced the blood pressure of both omega-3 PUFA-deficient and omega-3 PUFA-sufficient diet-fed Ren-2 rats. Body weight, body fat and plasma leptin were reduced by perindopril treatment but not affected by omega-3 PUFA supply. Given that the elevated blood pressure of the Ren-2 rat is mediated by ANG II, the data suggest that omega-3 PUFA may reduce hypertension via the renin-angiotensin system.
Collapse
Affiliation(s)
- A P Jayasooriya
- Howard Florey Institute, University of Melbourne, Victoria 3010, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Begg DP, Kent S, McKinley MJ, Mathai ML. Suppression of endotoxin-induced fever in near-term pregnant rats is mediated by brain nitric oxide. Am J Physiol Regul Integr Comp Physiol 2007; 292:R2174-8. [PMID: 17332165 DOI: 10.1152/ajpregu.00032.2007] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Over the last three decades, experiments in several mammalian species have shown that the febrile response to bacterial endotoxin is attenuated late in pregnancy. More recent evidence has established that the expression of nitric oxide synthase (NOS) enzymes is increased in the brain late in pregnancy. The current study investigated the possible role of brain nitric oxide in mediating the phenomenon of fever suppression. Core body temperature (Tb) of near-term pregnant rats ( day 19 and 20) was measured following inhibition of brain NOS and intraperitoneal injection of LPS (50 μg/kg); they were compared with both day 15 pregnant and virgin animals. Intracerebroventricular injection with an inhibitor of NOS, NG-monomethyl-l-arginine citrate (l-NMMA; 280 μg), in near-term pregnant rats restored the febrile response to LPS. As expected, near-term dams that received intracerebroventricular vehicle + IP LPS did not increase Tb, in contrast to the 1.0 ± 0.2°C rise in Tb in dams treated with ICV l-NMMA + IP LPS ( P < 0.01). In virgin females and day 15 pregnant controls receiving this treatment, the increases in Tb were 1.5 ± 0.3°C and 1.6 ± 0.4°C, respectively. Thus, blockade of brain NOS restored the febrile response to LPS in near-term dams; at 5 h postinjection, Tb was 60–70% of that observed in virgins and day 15 pregnant animals. Intracerebroventricular l-NMMA alone did not induce a significant change in Tb in any group. These results suggest that the mechanism underlying the suppression of the febrile response in near-term pregnancy is mediated by nitric oxide signaling in the brain.
Collapse
Affiliation(s)
- Denovan P Begg
- School of Psychological Science, La Trobe University, Bundoora, Victoria, 3086 Australia.
| | | | | | | |
Collapse
|
43
|
Attar-Bashi NM, Weisinger RS, Begg DP, Li D, Sinclair AJ. Failure of conjugated linoleic acid supplementation to enhance biosynthesis of docosahexaenoic acid from alpha-linolenic acid in healthy human volunteers. Prostaglandins Leukot Essent Fatty Acids 2007; 76:121-30. [PMID: 17275274 DOI: 10.1016/j.plefa.2006.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 10/11/2006] [Accepted: 11/07/2006] [Indexed: 11/18/2022]
Abstract
A rate-limiting step in docosahexaenoic acid (DHA) formation from alpha-linolenic acid (ALA) involves peroxisomal oxidation of 24:6n-3 to DHA. The aim of the study was to determine whether conjugated linoleic acid (CLA) would enhance conversion of ALA to DHA in humans on an ALA-supplemented diet. The subjects (n=8 per group) received daily supplementation of ALA (11g) and either CLA (3.2g) or placebo for 8 weeks. At baseline, 4 and 8 weeks, blood was collected for plasma fatty acid analysis and a number of physiological measures were examined. The ALA-supplemented diet increased plasma levels of ALA and eicosapentaenoic acid (EPA). The addition of CLA to the ALA diet resulted in increased plasma levels of CLA, as well as ALA and EPA. Plasma level of DHA was not increased with either the ALA alone or ALA plus CLA supplementation. The results demonstrated that CLA was not effective in enhancing DHA levels in plasma in healthy volunteers.
Collapse
Affiliation(s)
- N M Attar-Bashi
- School of Applied Sciences, RMIT University, Melbourne, Victoria, Australia
| | | | | | | | | |
Collapse
|
44
|
Weisinger RS, Begg DP, Chen N, Jois M, Mathai ML, Sinclair AJ. The problem of obesity: is there a role for antagonists of the renin-angiotensin system? Asia Pac J Clin Nutr 2007; 16 Suppl 1:359-67. [PMID: 17392133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Obesity is a major health problem worldwide; it is associated with more than 30 medical conditions and is a leading cause of unnecessary deaths. Adipose tissue not only acts as an energy store, but also behaves like an endocrine organ, synthesising and secreting numerous hormones and cytokines. Angiotensin II (ANG II) is the biologically active component of the renin-angiotensin system (RAS). The RAS is present in adipose tissue and evidence suggests that ANG II is intimately linked to obesity. Indeed, ANG II increases fat cell growth and differentiation, increases synthesis, uptake and storage of fatty acids and triglycerides and possibly inhibits lipolysis. Evidence obtained using genetically modified animals has shown that the amount of body fat is directly related to the amount of ANG II, i.e., animals with low levels of ANG II have reduced fat stores while animals with excessive ANG II have increased fat stores. In humans, epidemiological evidence has shown that body fat is correlated with angiotensinogen, a precursor of ANG II, or other components of the RAS. Furthermore, blocking the production and/or actions of ANG II with drugs or natural substances decreases body fat. The decrease in body fat caused by such treatments predominantly occurs in abdominal fat depots and appears to be independent of energy intake and digestibility. Clearly, ANG II has an important role in the accumulation of body fat and the possibility exists that treatment of obesity will be enhanced by the use of natural or synthetic substances that interfere with ANG II.
Collapse
Affiliation(s)
- Richard S Weisinger
- School of Psychological Science, La Trobe University, Bundoora 3086, Victoria, Australia.
| | | | | | | | | | | |
Collapse
|
45
|
Hallam KT, Olver JS, Chambers V, Begg DP, McGrath C, Norman TR. The heritability of melatonin secretion and sensitivity to bright nocturnal light in twins. Psychoneuroendocrinology 2006; 31:867-75. [PMID: 16769177 DOI: 10.1016/j.psyneuen.2006.04.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2005] [Revised: 04/12/2006] [Accepted: 04/13/2006] [Indexed: 11/19/2022]
Abstract
The super-sensitivity of the neurohormone melatonin to light in patients with bipolar disorder provides evidence of the circadian nature of the disorder. This response has been proposed as an endophenotype for identifying people at risk of the disorder and guiding investigations of molecular genetic targets. However, before this response is used as an endophenotypic marker, the heritable nature of melatonin sensitivity in the normal population must be established. The aim of this study was to investigate the heritability of nocturnal melatonin secretion and sensitivity to light in monozygotic and dizygotic twins with no psychiatric history. This study investigated overall melatonin levels (between 2000 and 2400 h) and suppression by 500 lx of light (between 2400 and 0100 h) in 20 pairs of twins (nine monozygotic, 11 dizygotic). The results indicate that melatonin secretion is highly heritable with secretion in one twin being a significant predictor of secretion in their twin in both monozygotic and dizygotic pairs. In relation to light sensitivity, genetic loading appears to play a significant role with the greatest concordance between monozygotic twins, followed by dizygotic twins and finally low concordance in unrelated individuals. This provides additional support for the usefulness of melatonin sensitivity to light as a potential endophenotypic marker of bipolar affective disorder.
Collapse
Affiliation(s)
- Karen T Hallam
- Department of Psychiatry, Austin Health, The University of Melbourne, Heidelberg Vic., Australia.
| | | | | | | | | | | |
Collapse
|
46
|
Begg DP, Hallam KT, Norman TR. Attenuation of benzodiazepine withdrawal anxiety in the rat by serotonin antagonists. Behav Brain Res 2005; 161:286-90. [PMID: 15922055 DOI: 10.1016/j.bbr.2005.02.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Revised: 02/11/2005] [Accepted: 02/17/2005] [Indexed: 10/25/2022]
Abstract
Administration of benzodiazepines is known to be associated with tolerance and a withdrawal syndrome on abrupt cessation. The aetiology of the withdrawal syndrome is not known but a role for the serotonin (5HT) system is suspected. The aim of the current study was to investigate the usefulness of 5-HT2 antagonists in the treatment of benzodiazepine withdrawal syndrome in the rat. Male Wistar rats were treated with either diazepam (4 mg/kg) or vehicle for 14 days, then abruptly withdrawn for 24h. Animals were tested in the social interaction paradigm and elevated plus maze. Some diazepam-withdrawn rats were pre-treated with 5HT2 antagonists 60 min before behavioural testing. Acute withdrawal from benzodiazepines significantly reduced social interaction between pairs compared to vehicle or diazepam-treated animals. Similarly, for the elevated plus maze withdrawn animals made fewer entries and spent less time on the open arms than did vehicle or diazepam-treated animals. Single doses of 5-HT2 antagonists, mianserin (5mg/kg) and ritanserin (1mg/kg), effectively ameliorated withdrawal anxiety in the rat, returning behavioural function in the social interaction test and elevated plus maze to levels comparable to vehicle-treated animals.
Collapse
Affiliation(s)
- Denovan P Begg
- La Trobe University School of Psychological Science, Australia
| | | | | |
Collapse
|