1
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Gerstenberg MK, Andersen DB, Torz L, Castorena CM, Bookout AL, Hartmann B, Rehfeld JF, Petersen N, Holst JJ, Kuhre RE. Weight loss by calorie restriction does not alter appetite-regulating gut hormone responses from perfused rat small intestine. Acta Physiol (Oxf) 2023; 238:e13947. [PMID: 36755506 DOI: 10.1111/apha.13947] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 01/27/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023]
Abstract
AIM Postprandial secretion of the appetite-inhibiting hormones, glucagon-like peptide-1 (GLP-1), and peptide YY are reduced with obesity. It is unclear if the reduced secretion persists following weight loss (WL), if other appetite-inhibiting hormones are also reduced, and if so whether reduced secretion results from intrinsic changes in the gut. METHODS To address whether WL may restore secretion of GLP-1 and other appetite-inhibiting hormones, we performed a gut perfusion study of the small intestine in diet-induced obese (DIO) rats after WL. A 20% weight loss (means ± SEM (g): 916 ± 53 vs. 703 ± 35, p < 0.01, n = 7) was induced by calorie restriction, and maintained stable for ≥7 days prior to gut perfusion to allow for complete renewal of enteroendocrine cells. Age-matched DIO rats were used as comparator. Several gut hormones were analyzed from the venous effluent, and gene expression was performed on gut tissue along the entire length of the intestine. RESULTS Secretion of cholecystokinin, gastrin, glucose-dependent insulinotropic peptide, GLP-1, neurotensin, and somatostatin was not affected by WL during basal conditions (p ≥ 0.25) or in response to macronutrients and bile acids (p ≥ 0.14). Glucose absorption was indistinguishable following WL. The expression of genes encoding the studied peptides, macronutrient transporters (glucose, fructose, and di-/tripeptides) and bile acid receptors did also not differ between DIO and WL groups. CONCLUSIONS These data suggest that the attenuated postprandial responses of GLP-1, as well as reduced responses of other appetite-inhibiting gut hormones, in people living with obesity may persist after weight loss and may contribute to their susceptibility for weight regain.
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Affiliation(s)
| | - Daniel B Andersen
- Department of Biomedical Sciences, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Center for Basic Metabolic Research, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Lola Torz
- Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
| | | | - Angie L Bookout
- Global Drug Discovery, Novo Nordisk A/S, Seattle, Washington, USA
| | - Bolette Hartmann
- Department of Biomedical Sciences, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Center for Basic Metabolic Research, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Jens F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | | | - Jens J Holst
- Department of Biomedical Sciences, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Novo Nordisk Center for Basic Metabolic Research, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | - Rune E Kuhre
- Department of Biomedical Sciences, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark.,Global Drug Discovery, Novo Nordisk A/S, Måløv, Denmark
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2
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Petersen N, Greiner TU, Torz L, Bookout A, Gerstenberg MK, Castorena CM, Kuhre RE. Targeting the Gut in Obesity: Signals from the Inner Surface. Metabolites 2022; 12:metabo12010039. [PMID: 35050161 PMCID: PMC8778595 DOI: 10.3390/metabo12010039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/26/2021] [Accepted: 12/31/2021] [Indexed: 12/17/2022] Open
Abstract
Obesity is caused by prolonged energy surplus. Current anti-obesity medications are mostly centralized around the energy input part of the energy balance equation by increasing satiety and reducing appetite. Our gastrointestinal tract is a key organ for regulation of food intake and supplies a tremendous number of circulating signals that modulate the activity of appetite-regulating areas of the brain by either direct interaction or through the vagus nerve. Intestinally derived messengers are manifold and include absorbed nutrients, microbial metabolites, gut hormones and other enterokines, collectively comprising a fine-tuned signalling system to the brain. After a meal, nutrients directly interact with appetite-inhibiting areas of the brain and induce satiety. However, overall feeding behaviour also depends on secretion of gut hormones produced by highly specialized and sensitive enteroendocrine cells. Moreover, circulating microbial metabolites and their interactions with enteroendocrine cells further contribute to the regulation of feeding patterns. Current therapies exploiting the appetite-regulating properties of the gut are based on chemically modified versions of the gut hormone, glucagon-like peptide-1 (GLP-1) or on inhibitors of the primary GLP-1 inactivating enzyme, dipeptidyl peptidase-4 (DPP-4). The effectiveness of these approaches shows that that the gut is a promising target for therapeutic interventions to achieve significant weigh loss. We believe that increasing understanding of the functionality of the intestinal epithelium and new delivery systems will help develop selective and safe gut-based therapeutic strategies for improved obesity treatment in the future. Here, we provide an overview of the major homeostatic appetite-regulating signals generated by the intestinal epithelial cells and how these signals may be harnessed to treat obesity by pharmacological means.
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Affiliation(s)
- Natalia Petersen
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk A/S, Novo Park 1, 2670 Måløv, Denmark; (L.T.); (M.K.G.); (R.E.K.)
- Correspondence:
| | - Thomas U. Greiner
- The Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Lola Torz
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk A/S, Novo Park 1, 2670 Måløv, Denmark; (L.T.); (M.K.G.); (R.E.K.)
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Angie Bookout
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk Research Center, Seattle, WA 98109, USA; (A.B.); (C.M.C.)
| | - Marina Kjærgaard Gerstenberg
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk A/S, Novo Park 1, 2670 Måløv, Denmark; (L.T.); (M.K.G.); (R.E.K.)
| | - Carlos M. Castorena
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk Research Center, Seattle, WA 98109, USA; (A.B.); (C.M.C.)
| | - Rune Ehrenreich Kuhre
- Global Obesity and Liver Disease Research, Global Drug Discovery, Novo Nordisk A/S, Novo Park 1, 2670 Måløv, Denmark; (L.T.); (M.K.G.); (R.E.K.)
- Department of Veterinary and Animal Science, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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3
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Wang S, Zhu Q, Liang G, Franks T, Boucher M, Bence KK, Lu M, Castorena CM, Zhao S, Elmquist JK, Scherer PE, Horton JD. Response to Kunos et al. and Lotersztajn and Mallat. J Clin Invest 2022; 132:e156247. [PMID: 34981782 PMCID: PMC8718155 DOI: 10.1172/jci156247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
| | | | - Guosheng Liang
- Department of Internal Medicine and
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Tania Franks
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA
| | - Magalie Boucher
- Drug Safety Research and Development, Pfizer Inc., Groton, Connecticut, and Cambridge, Massachusetts, USA
| | - Kendra K. Bence
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA
| | - Mingjian Lu
- Internal Medicine Research Unit, Pfizer Worldwide Research, Development, and Medical, Cambridge, Massachusetts, USA
| | | | | | | | | | - Jay D. Horton
- Department of Internal Medicine and
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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4
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Wang S, Zhu Q, Liang G, Franks T, Boucher M, Bence KK, Lu M, Castorena CM, Zhao S, Elmquist JK, Scherer PE, Horton JD. Cannabinoid receptor-1 signaling in hepatocytes and stellate cells does not contribute to NAFLD. J Clin Invest 2021; 131:e152242. [PMID: 34499619 DOI: 10.1172/jci152242] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 08/31/2021] [Indexed: 11/17/2022] Open
Abstract
The endocannabinoid system regulates appetite and energy expenditure and inhibitors of the cannabinoid receptor-1 (CB-1) induce weight loss with improvement in components of the metabolic syndrome. While CB-1 blockage in brain is responsible for weight loss, many of the metabolic benefits associated with CB-1 blockade have been attributed to inhibition of CB-1 signaling in the periphery. As a result, there has been interest in developing a peripherally restricted CB-1 inhibitor for the treatment of nonalcoholic fatty liver disease (NAFLD) that would lack the unwanted centrally mediated side effects. Here, we produced mice that lacked CB-1 receptors in hepatocytes or stellate cells to determine if CB-1 signaling contributes to the development of NAFLD or liver fibrosis. Deletion of CB-1 receptors in hepatocytes did not alter the development of NAFLD in mice fed a high sucrose high fat diet or high fat diet (HFD). Similarly, deletion of CB-1 deletion specifically in stellate cells also did not prevent the development of NAFLD in mice fed the HFD nor did it protect mice for carbon tetrachloride (CCl4)-induced fibrosis. Combined, these studies do not support a direct role for hepatocyte or stellate cell CB-1 signaling in the development of NAFLD or liver fibrosis.
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Affiliation(s)
- Simeng Wang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Qingzhang Zhu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Guosheng Liang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center at Dallas, Dallas, United States of America
| | - Tania Franks
- Drug Safety Research and Development, Pfizer Inc, Cambridge, United States of America
| | - Magalie Boucher
- Drug Safety Research and Development, Pfizer Inc, Cambridge, United States of America
| | - Kendra K Bence
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, United States of America
| | - Mingjian Lu
- Internal Medicine Research Unit, Pfizer Inc, Cambridge, United States of America
| | - Carlos M Castorena
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Shangang Zhao
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Joel K Elmquist
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Philipp E Scherer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
| | - Jay D Horton
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States of America
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5
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Castorena CM, Caron A, Michael NJ, Ahmed NI, Arnold AG, Lee J, Lee C, Limboy C, Tinajero AS, Granier M, Wang S, Horton JD, Holland WL, Lee S, Liu C, Fujikawa T, Elmquist JK. CB1Rs in VMH neurons regulate glucose homeostasis but not body weight. Am J Physiol Endocrinol Metab 2021; 321:E146-E155. [PMID: 34097543 PMCID: PMC8321828 DOI: 10.1152/ajpendo.00044.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 01/24/2023]
Abstract
Cannabinoid 1 receptor (CB1R) inverse agonists reduce body weight and improve several parameters of glucose homeostasis. However, these drugs have also been associated with deleterious side effects. CB1R expression is widespread in the brain and in peripheral tissues, but whether specific sites of expression can mediate the beneficial metabolic effects of CB1R drugs, while avoiding the untoward side effects, remains unclear. Evidence suggests inverse agonists may act on key sites within the central nervous system to improve metabolism. The ventromedial hypothalamus (VMH) is a critical node regulating energy balance and glucose homeostasis. To determine the contributions of CB1Rs expressed in VMH neurons in regulating metabolic homeostasis, we generated mice lacking CB1Rs in the VMH. We found that the deletion of CB1Rs in the VMH did not affect body weight in chow- and high-fat diet-fed male and female mice. We also found that deletion of CB1Rs in the VMH did not alter weight loss responses induced by the CB1R inverse agonist SR141716. However, we did find that CB1Rs of the VMH regulate parameters of glucose homeostasis independent of body weight in diet-induced obese male mice.NEW & NOTEWORTHY Cannabinoid 1 receptors (CB1Rs) regulate metabolic homeostasis, and CB1R inverse agonists reduce body weight and improve parameters of glucose metabolism. However, the cell populations expressing CB1Rs that regulate metabolic homeostasis remain unclear. CB1Rs are highly expressed in the ventromedial hypothalamic nucleus (VMH), which is a crucial node that regulates metabolism. With CRISPR/Cas9, we generated mice lacking CB1Rs specifically in VMH neurons and found that CB1Rs in VMH neurons are essential for the regulation of glucose metabolism independent of body weight regulation.
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Affiliation(s)
- Carlos M Castorena
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Alexandre Caron
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Natalie J Michael
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Newaz I Ahmed
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Amanda G Arnold
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jiwon Lee
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Charlotte Lee
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Chelsea Limboy
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Arely Salazar Tinajero
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Madison Granier
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Simeng Wang
- Department of Molecular Genetics, University of Utah, Salt Lake City, Utah
| | - Jay D Horton
- Department of Molecular Genetics, University of Utah, Salt Lake City, Utah
| | - William L Holland
- Department of Biochemistry, Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Syann Lee
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Chen Liu
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Teppei Fujikawa
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joel K Elmquist
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas
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6
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Michael NJ, Caron A, Lee CE, Castorena CM, Lee S, Zigman JM, Williams KW, Elmquist JK. Melanocortin regulation of histaminergic neurons via perifornical lateral hypothalamic melanocortin 4 receptors. Mol Metab 2020; 35:100956. [PMID: 32244183 PMCID: PMC7082550 DOI: 10.1016/j.molmet.2020.01.020] [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] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 01/23/2020] [Accepted: 01/28/2020] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVE Histaminergic neurons of the tuberomammillary nucleus (TMN) are wake-promoting and contribute to the regulation of energy homeostasis. Evidence indicates that melanocortin 4 receptors (MC4R) are expressed within the TMN. However, whether the melanocortin system influences the activity and function of TMN neurons expressing histidine decarboxylase (HDC), the enzyme required for histamine synthesis, remains undefined. METHODS We utilized Hdc-Cre mice in combination with whole-cell patch-clamp electrophysiology and in vivo chemogenetic techniques to determine whether HDC neurons receive metabolically relevant information via the melanocortin system. RESULTS We found that subsets of HDC-expressing neurons were excited by melanotan II (MTII), a non-selective melanocortin receptor agonist. Use of melanocortin receptor selective agonists (THIQ, [D-Trp8]-γ-MSH) and inhibitors of synaptic transmission (TTX, CNQX, AP5) indicated that the effect was mediated specifically by MC4Rs and involved a glutamatergic dependent presynaptic mechanism. MTII enhanced evoked excitatory post-synaptic currents (EPSCs) originating from electrical stimulation of the perifornical lateral hypothalamic area (PeFLH), supportive of melanocortin effects on the glutamatergic PeFLH projection to the TMN. Finally, in vivo chemogenetic inhibition of HDC neurons strikingly enhanced the anorexigenic effects of intracerebroventricular administration of MTII, suggesting that MC4R activation of histaminergic neurons may restrain the anorexigenic effects of melanocortin system activation. CONCLUSIONS These experiments identify a functional interaction between the melanocortin and histaminergic systems and suggest that HDC neurons act naturally to restrain the anorexigenic effect of melanocortin system activation. These findings may have implications for the control of arousal and metabolic homeostasis, especially in the context of obesity, in which both processes are subjected to alterations.
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MESH Headings
- Animals
- Behavior, Animal/drug effects
- Eating/drug effects
- Excitatory Postsynaptic Potentials/drug effects
- Histamine/metabolism
- Histidine Decarboxylase/genetics
- Histidine Decarboxylase/metabolism
- Hypothalamic Area, Lateral/cytology
- Hypothalamic Area, Lateral/metabolism
- Locomotion/drug effects
- Male
- Melanocortins/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Neurons/drug effects
- Neurons/metabolism
- Peptides, Cyclic/pharmacology
- Receptor, Melanocortin, Type 4/agonists
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- alpha-MSH/analogs & derivatives
- alpha-MSH/pharmacology
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Affiliation(s)
- Natalie J Michael
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Alexandre Caron
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Charlotte E Lee
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Carlos M Castorena
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Syann Lee
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA
| | - Kevin W Williams
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA.
| | - Joel K Elmquist
- Center for Hypothalamic Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA; Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, 75390-9077, USA.
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7
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Peri-Okonny P, Baskin KK, Iwamoto G, Mitchell JH, Smith SA, Kim HK, Szweda LI, Bassel-Duby R, Fujikawa T, Castorena CM, Richardson J, Shelton JM, Ayers C, Berry JD, Malladi VS, Hu MC, Moe OW, Scherer PE, Vongpatanasin W. High-Phosphate Diet Induces Exercise Intolerance and Impairs Fatty Acid Metabolism in Mice. Circulation 2019; 139:1422-1434. [PMID: 30612451 DOI: 10.1161/circulationaha.118.037550] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [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: 01/14/2023]
Abstract
BACKGROUND Inorganic phosphate (Pi) is used extensively as a preservative and a flavor enhancer in the Western diet. Physical inactivity, a common feature of Western societies, is associated with increased cardiovascular morbidity and mortality. It is unknown whether dietary Pi excess contributes to exercise intolerance and physical inactivity. METHODS To determine an association between Pi excess and physical activity in humans, we assessed the relationship between serum Pi and actigraphy-determined physical activity level, as well as left ventricular function by cardiac magnetic resonance imaging, in DHS-2 (Dallas Heart Study phase 2) participants after adjusting for relevant variables. To determine direct effects of dietary Pi on exercise capacity, oxygen uptake, serum nonesterified fatty acid, and glucose were measured during exercise treadmill test in C57/BL6 mice fed either a high-Pi (2%) or normal-Pi (0.6%) diet for 12 weeks. To determine the direct effect of Pi on muscle metabolism and expression of genes involved in fatty acid metabolism, additional studies in differentiated C2C12 myotubes were conducted after subjecting to media containing 1 to 3 mmol/L Pi (pH 7.0) to simulate in vivo phosphate conditions. RESULTS In participants of the DHS-2 (n=1603), higher serum Pi was independently associated with reduced time spent in moderate to vigorous physical activity ( P=0.01) and increased sedentary time ( P=0.004). There was no association between serum Pi and left ventricular ejection fraction or volumes. In animal studies, compared with the control diet, consumption of high-Pi diet for 12 weeks did not alter body weight or left ventricular function but reduced maximal oxygen uptake, treadmill duration, spontaneous locomotor activity, fat oxidation, and fatty acid levels and led to downregulation of genes involved in fatty acid synthesis, release, and oxidation, including Fabp4, Hsl, Fasn, and Pparγ, in muscle. Similar results were recapitulated in vitro by incubating C2C12 myotubes with high-Pi media. CONCLUSIONS Our data demonstrate a detrimental effect of dietary Pi excess on skeletal muscle fatty acid metabolism and exercise capacity that is independent of obesity and cardiac contractile function. Dietary Pi may represent a novel and modifiable target to reduce physical inactivity associated with the Western diet.
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Affiliation(s)
- Poghni Peri-Okonny
- Department of Internal Medicine, Hypertension Section (P.P.-O., H.K.K., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Kedryn K Baskin
- Department of Molecular Biology (K.K.B., R.B.-D.), University of Texas Southwestern Medical Center, Dallas.,Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus (K.K.B.)
| | - Gary Iwamoto
- Department of Cell Biology (G.I.), University of Texas Southwestern Medical Center, Dallas
| | - Jere H Mitchell
- Department of Internal Medicine, Cardiology Division (J.H.M., L.I.S., J.M.S., J.D.B., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Scott A Smith
- Department of Health Care Sciences (S.A.S.), University of Texas Southwestern Medical Center, Dallas
| | - Han Kyul Kim
- Department of Internal Medicine, Hypertension Section (P.P.-O., H.K.K., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Luke I Szweda
- Department of Internal Medicine, Cardiology Division (J.H.M., L.I.S., J.M.S., J.D.B., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Rhonda Bassel-Duby
- Department of Molecular Biology (K.K.B., R.B.-D.), University of Texas Southwestern Medical Center, Dallas
| | - Teppei Fujikawa
- Department of Cellular and Integrative Physiology, Long School of Medicine, University of Texas Health San Antonio (T.F.)
| | - Carlos M Castorena
- Department of Internal Medicine, Division of Hypothalamic Research (C.M.C.), University of Texas Southwestern Medical Center, Dallas
| | - James Richardson
- Department of Pathology (J.R.), University of Texas Southwestern Medical Center, Dallas
| | - John M Shelton
- Department of Internal Medicine, Cardiology Division (J.H.M., L.I.S., J.M.S., J.D.B., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Colby Ayers
- Department of Clinical Sciences (C.A., J.D.B.), University of Texas Southwestern Medical Center, Dallas
| | - Jarett D Berry
- Department of Internal Medicine, Cardiology Division (J.H.M., L.I.S., J.M.S., J.D.B., W.V.), University of Texas Southwestern Medical Center, Dallas.,Department of Clinical Sciences (C.A., J.D.B.), University of Texas Southwestern Medical Center, Dallas
| | - Venkat S Malladi
- Department of Bioinformatics (V.S.M.), University of Texas Southwestern Medical Center, Dallas
| | - Ming-Chang Hu
- Department of Internal Medicine, Division of Nephrology (M.-C.H., O.W.M.), University of Texas Southwestern Medical Center, Dallas.,Department of Physiology (M.-C.H., O.W.M.), University of Texas Southwestern Medical Center, Dallas.,Pak Center of Mineral Metabolism and Clinical Research (M.-C.H., O.W.M., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Orson W Moe
- Department of Internal Medicine, Division of Nephrology (M.-C.H., O.W.M.), University of Texas Southwestern Medical Center, Dallas.,Department of Physiology (M.-C.H., O.W.M.), University of Texas Southwestern Medical Center, Dallas.,Pak Center of Mineral Metabolism and Clinical Research (M.-C.H., O.W.M., W.V.), University of Texas Southwestern Medical Center, Dallas
| | - Philipp E Scherer
- Touchstone Diabetes Center (P.E.S.), University of Texas Southwestern Medical Center, Dallas
| | - Wanpen Vongpatanasin
- Department of Internal Medicine, Hypertension Section (P.P.-O., H.K.K., W.V.), University of Texas Southwestern Medical Center, Dallas.,Department of Internal Medicine, Cardiology Division (J.H.M., L.I.S., J.M.S., J.D.B., W.V.), University of Texas Southwestern Medical Center, Dallas.,Pak Center of Mineral Metabolism and Clinical Research (M.-C.H., O.W.M., W.V.), University of Texas Southwestern Medical Center, Dallas
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8
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Mani BK, Castorena CM, Vianna CR, Lee CE, Metzger NP, Vijayaraghavan P, Osborne-Lawrence S, Elmquist JK, Zigman JM. Combined Loss of Ghrelin Receptor and Cannabinoid CB1 Receptor in Mice Decreases Survival but does not Additively Reduce Body Weight or Eating. Neuroscience 2019; 447:53-62. [PMID: 31520709 DOI: 10.1016/j.neuroscience.2019.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/28/2019] [Accepted: 09/02/2019] [Indexed: 01/08/2023]
Abstract
Ghrelin administration increases food intake, body weight (BW), adiposity, and blood glucose. In contrast, although mouse models lacking ghrelin or its receptor (Growth Hormone Secretagogue Receptor (GHSR)) exhibit life-threatening hypoglycemia in starvation-like states, they do not exhibit appreciable reductions in food intake, BW, adiposity, blood glucose, or survival when food availability is unrestricted. This suggests the existence of a parallel neuromodulatory system that can compensate for disruptions in the ghrelin system in certain settings. Here, we hypothesized that the cannabinoid CB1 receptor (CB1R) may encode this putative redundancy, and as such, that genetic deletion of both GHSR and CB1R would exaggerate the metabolic deficits associated with deletion of GHSR alone. To test this hypothesis, we assessed food intake, BW, blood glucose, survival, and plasma acyl-ghrelin in ad libitum-fed male wild-type mice and those that genetically lack GHSR (GHSR-nulls), CB1R (CB1R-nulls), or both GHSR and CB1R (double-nulls). BW, fat mass, and lean mass were similar in GHSR-nulls and wild-types, lower in CB1R-nulls, but not further reduced in double-nulls. Food intake, plasma acyl-ghrelin, and blood glucose were similar among genotypes. Deletion of either GHSR or CB1R alone did not have a statistically-significant effect on survival, but double-nulls demonstrated a statistical trend towards decreased survival (p = 0.07). We conclude that CB1R is not responsible for the normal BW, adiposity, food intake, and blood glucose observed in GHSR-null mice in the setting of unrestricted food availability. Nor is CB1R required for plasma acyl-ghrelin secretion in that setting. However, GHSR may be protective against exaggerated mortality associated with CB1R deletion.
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Affiliation(s)
- Bharath K Mani
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Carlos M Castorena
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Claudia R Vianna
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Charlotte E Lee
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nathan P Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Prasanna Vijayaraghavan
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joel K Elmquist
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology & Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology & Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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9
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Caron A, Reynolds RP, Castorena CM, Michael NJ, Lee CE, Lee S, Berdeaux R, Scherer PE, Elmquist JK. Adipocyte Gs but not Gi signaling regulates whole-body glucose homeostasis. Mol Metab 2019; 27:11-21. [PMID: 31279640 PMCID: PMC6717754 DOI: 10.1016/j.molmet.2019.06.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/20/2019] [Accepted: 06/20/2019] [Indexed: 01/24/2023] Open
Abstract
Objective The sympathetic nervous system (SNS) is a key regulator of the metabolic and endocrine functions of adipose tissue. Increased SNS outflow promotes fat mobilization, stimulates non-shivering thermogenesis, promotes browning, and inhibits leptin production. Most of these effects are attributed to norepinephrine activation of the Gs-coupled beta adrenergic receptors located on the surface of the adipocytes. Evidence suggests that other adrenergic receptor subtypes, including the Gi-coupled alpha 2 adrenergic receptors might also mediate the SNS effects on adipose tissue. However, the impact of acute stimulation of adipocyte Gs and Gi has never been reported. Methods We harness the power of chemogenetics to develop unique mouse models allowing the specific and spatiotemporal stimulation of adipose tissue Gi and Gs signaling. We evaluated the impact of chemogenetic stimulation of these pathways on glucose homeostasis, lipolysis, leptin production, and gene expression. Results Stimulation of Gs signaling in adipocytes induced rapid and sustained hypoglycemia. These hypoglycemic effects were secondary to increased insulin release, likely consequent to increased lipolysis. Notably, we also observed differences in gene regulation and ex vivo lipolysis in different adipose depots. In contrast, acute stimulation of Gi signaling in adipose tissue did not affect glucose metabolism or lipolysis, but regulated leptin production. Conclusion Our data highlight the significance of adipose Gs signaling in regulating systemic glucose homeostasis. We also found previously unappreciated heterogeneity across adipose depots following acute stimulation. Together, these results highlight the complex interactions of GPCR signaling in adipose tissue and demonstrate the usefulness of chemogenetic technology to better understand adipocyte function. Chemogenetic stimulation of Gs signaling in adipose tissue potently induces hypoglycemia in mice. The magnitude by which adipose Gs stimulation reduces blood glucose is similar to the hypoglycemic effects of insulin. Chemogenetic stimulation of Gs signaling in adipose tissue ex vivo stimulates lipolysis. Chemogenetic stimulation of adipose Gi signaling does not affect glycemia or lipolysis, but increases leptin levels. Our data demonstrate the usefulness of chemogenetic technology to understand adipocytes functions.
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Affiliation(s)
- Alexandre Caron
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Ryan P Reynolds
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Carlos M Castorena
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Natalie J Michael
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Charlotte E Lee
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Syann Lee
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, Center for Metabolic and Degenerative Diseases at the Brown Foundation, Institute of Molecular Medicine, McGovern Medical School at The University of Texas Health Science Center at Houston (UTHealth), Graduate Program in Biochemistry and Cell Biology, MD Anderson Cancer Center-UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joel K Elmquist
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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10
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de Groot MHM, Castorena CM, Cox KH, Kumar V, Mohawk JA, Ahmed NI, Takahashi JS. A novel mutation in Slc2a4 as a mouse model of fatigue. Genes Brain Behav 2019; 18:e12578. [PMID: 31059591 DOI: 10.1111/gbb.12578] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/01/2019] [Accepted: 05/02/2019] [Indexed: 11/28/2022]
Abstract
Chronic fatigue is a debilitating disorder with widespread consequences, but effective treatment strategies are lacking. Novel genetic mouse models of fatigue may prove invaluable for studying its underlying physiological mechanisms and for testing treatments and interventions. In a screen of voluntary wheel-running behavior in N-ethyl-N-nitrosourea mutagenized C57BL/6J mice, we discovered two lines with low body weights and aberrant wheel-running patterns suggestive of a fatigue phenotype. Affected progeny from these lines had lower daily activity levels and exhibited low amplitude circadian rhythm alterations. Their aberrant behavior was characterized by frequent interruptions and periods of inactivity throughout the dark phase of the light-dark cycle and increased levels of activity during the rest or light phase. Expression of the behavioral phenotypes in offspring of strategic crosses was consistent with a recessive inheritance pattern. Mapping of phenotypic abnormalities showed linkage with a single locus on chromosome 1, and whole exome sequencing identified a single point mutation in the Slc2a4 gene encoding the GLUT4 insulin-responsive glucose transporter. The single nucleotide change (A-T, which we named "twiggy") was in the distal end of exon 10 and resulted in a premature stop (Y440*). Additional metabolic phenotyping confirmed that these mice recapitulate phenotypes found in GLUT4 knockout mice. However, to the best of our knowledge, this is the first time a mutation in this gene has been shown to result in extensive changes in general behavioral patterns. These findings suggest that GLUT4 may be involved in circadian behavioral abnormalities and could provide insights into fatigue in humans.
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Affiliation(s)
- Marleen H M de Groot
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Carlos M Castorena
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kimberly H Cox
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Vivek Kumar
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Jennifer A Mohawk
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Newaz I Ahmed
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Joseph S Takahashi
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, Texas.,Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas
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11
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He Z, Gao Y, Alhadeff AL, Castorena CM, Huang Y, Lieu L, Afrin S, Sun J, Betley JN, Guo H, Williams KW. Cellular and synaptic reorganization of arcuate NPY/AgRP and POMC neurons after exercise. Mol Metab 2018; 18:107-119. [PMID: 30292523 PMCID: PMC6308029 DOI: 10.1016/j.molmet.2018.08.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 08/30/2018] [Indexed: 01/04/2023] Open
Abstract
OBJECTIVE Hypothalamic Pro-opiomelanocortin (POMC) and Neuropeptide Y/Agouti-Related Peptide (NPY/AgRP) neurons are critical nodes of a circuit within the brain that sense key metabolic cues as well as regulate metabolism. Importantly, these neurons retain an innate ability to rapidly reorganize synaptic inputs and electrophysiological properties in response to metabolic state. While the cellular properties of these neurons have been investigated in the context of obesity, much less is known about the effects of exercise training. METHODS In order to further investigate this issue, we utilized neuron-specific transgenic mouse models to identify POMC and NPY/AgRP neurons for patch-clamp electrophysiology experiments. RESULTS Using whole-cell patch-clamp electrophysiology, we found exercise depolarized and increased firing rate of arcuate POMC neurons. The increased excitability of POMC neurons was concomitant with increased excitatory inputs to these neurons. In agreement with recent work suggesting leptin plays an important role in the synaptic (re)organization of POMC neurons, POMC neurons which express leptin receptors were more sensitive to exercise-induced changes in biophysical properties. Opposite to effects observed in POMC neurons, NPY neurons were shunted toward inhibition following exercise. CONCLUSIONS Together, these data support a rapid reorganization of synaptic inputs and biophysical properties in response to exercise, which may facilitate adaptations to altered energy balance and glucose metabolism.
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Affiliation(s)
- Zhenyan He
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China; Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Yong Gao
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA; National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100005, China
| | - Amber L Alhadeff
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Carlos M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Yiru Huang
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China; Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Linh Lieu
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Sadia Afrin
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - Jia Sun
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA
| | - J Nicholas Betley
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hongbo Guo
- The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China
| | - Kevin W Williams
- Division of Hypothalamic Research, Department of Internal Medicine, the University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA.
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12
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Caron A, Dungan Lemko HM, Castorena CM, Fujikawa T, Lee S, Lord CC, Ahmed N, Lee CE, Holland WL, Liu C, Elmquist JK. POMC neurons expressing leptin receptors coordinate metabolic responses to fasting via suppression of leptin levels. eLife 2018. [PMID: 29528284 PMCID: PMC5866097 DOI: 10.7554/elife.33710] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Leptin is critical for energy balance, glucose homeostasis, and for metabolic and neuroendocrine adaptations to starvation. A prevalent model predicts that leptin’s actions are mediated through pro-opiomelanocortin (POMC) neurons that express leptin receptors (LEPRs). However, previous studies have used prenatal genetic manipulations, which may be subject to developmental compensation. Here, we tested the direct contribution of POMC neurons expressing LEPRs in regulating energy balance, glucose homeostasis and leptin secretion during fasting using a spatiotemporally controlled Lepr expression mouse model. We report a dissociation between leptin’s effects on glucose homeostasis versus energy balance in POMC neurons. We show that these neurons are dispensable for regulating food intake, but are required for coordinating hepatic glucose production and for the fasting-induced fall in leptin levels, independent of changes in fat mass. We also identify a role for sympathetic nervous system regulation of the inhibitory adrenergic receptor (ADRA2A) in regulating leptin production. Collectively, our findings highlight a previously unrecognized role of POMC neurons in regulating leptin levels.
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Affiliation(s)
- Alexandre Caron
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | | | - Carlos M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Teppei Fujikawa
- Department of Cellular and Integrative Physiology, UT Health San Antonio, San Antonio, United States
| | - Syann Lee
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Caleb C Lord
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Newaz Ahmed
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Charlotte E Lee
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - William L Holland
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Chen Liu
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joel K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
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13
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Mani BK, Castorena CM, Osborne-Lawrence S, Vijayaraghavan P, Metzger NP, Elmquist JK, Zigman JM. Ghrelin mediates exercise endurance and the feeding response post-exercise. Mol Metab 2018; 9:114-130. [PMID: 29396372 PMCID: PMC5870098 DOI: 10.1016/j.molmet.2018.01.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/19/2022] Open
Abstract
Objective Exercise training has several well-established health benefits, including many related to body weight, appetite control, and blood glucose homeostasis. However, the molecular mechanisms and, in particular, the hormonal systems that mediate and integrate these beneficial effects are poorly understood. In the current study, we aimed to investigate the role of the hormone ghrelin and its receptor, the growth hormone secretagogue receptor (GHSR; ghrelin receptor), in mediating the effects of exercise on food intake and blood glucose following exercise as well as in regulating exercise endurance capacity. Methods We used two mouse models of treadmill running to characterize the changes in plasma ghrelin with exercise. We also assessed the role of the ghrelin system to influence food intake and blood glucose after exercise, exercise endurance, and parameters potentially linked to responses to exercise. Mice lacking GHSRs (GHSR-null mice) and wild-type littermates were studied. Results An acute bout of exercise transiently elevated plasma acyl-ghrelin. Without the action of this increased ghrelin on GHSRs (as in GHSR-null mice), high intensity interval exercise markedly reduced food intake compared to control mice. The effect of exercise to acutely raise blood glucose remained unmodified in GHSR-null mice. Exercise-induced increases in plasma ghrelin positively correlated with endurance capacity, and time to exhaustion was reduced in GHSR-null mice as compared to wild-type littermates. In an effort to mechanistically explain their reduced exercise endurance, exercised GHSR-null mice exhibited an abrogated sympathoadrenal response, lower overall insulin-like growth factor-1 levels, and altered glycogen utilization. Conclusions Exercise transiently increases plasma ghrelin. GHSR-null mice exhibit decreased food intake following high intensity interval exercise and decreased endurance when submitted to an exercise endurance protocol. These data suggest that an intact ghrelin system limits the capacity of exercise to restrict food intake following exercise, although it enhances exercise endurance. High intensity exercise transiently increases plasma ghrelin. Without ghrelin action on its receptors (growth hormone secretagogue receptors), exercise markedly reduces food intake. An intact ghrelin system enhances exercise endurance.
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Affiliation(s)
- Bharath K Mani
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Carlos M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sherri Osborne-Lawrence
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Prasanna Vijayaraghavan
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nathan P Metzger
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joel K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology & Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jeffrey M Zigman
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Division of Endocrinology & Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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14
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Fujikawa T, Castorena CM, Lee S, Elmquist JK. The hypothalamic regulation of metabolic adaptations to exercise. J Neuroendocrinol 2017; 29:10.1111/jne.12533. [PMID: 28887871 PMCID: PMC6264914 DOI: 10.1111/jne.12533] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [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] [Received: 09/01/2017] [Accepted: 09/01/2017] [Indexed: 12/16/2022]
Abstract
Our modern lifestyle is characterised by easy access to nutrient dense foods combined with limited physical activity. A sedentary lifestyle is one of several factors that have contributed to the global obesity epidemic and it also predisposes to chronic illnesses such as diabetes and cardiovascular disease. Although many studies have focused on the benefits of exercise in peripheral tissues, the contributions of the central nervous system to these exercise-induced metabolic adaptations are relatively unknown. The present review highlights the role of the ventromedial hypothalamus in regulating the metabolic response to exercise.
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Affiliation(s)
- T Fujikawa
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Cellular and Integrative Physiology, The University of Texas Health San Antonio, San Antonio, TX, USA
| | - C M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - S Lee
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - J K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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15
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Lord CC, Wyler SC, Wan R, Castorena CM, Ahmed N, Mathew D, Lee S, Liu C, Elmquist JK. The atypical antipsychotic olanzapine causes weight gain by targeting serotonin receptor 2C. J Clin Invest 2017; 127:3402-3406. [PMID: 28805659 DOI: 10.1172/jci93362] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 06/29/2017] [Indexed: 11/17/2022] Open
Abstract
Atypical antipsychotics such as olanzapine often induce excessive weight gain and type 2 diabetes. However, the mechanisms underlying these drug-induced metabolic perturbations remain poorly understood. Here, we used an experimental model that reproduces olanzapine-induced hyperphagia and obesity in female C57BL/6 mice. We found that olanzapine treatment acutely increased food intake, impaired glucose tolerance, and altered physical activity and energy expenditure in mice. Furthermore, olanzapine-induced hyperphagia and weight gain were blunted in mice lacking the serotonin 2C receptor (HTR2C). Finally, we showed that treatment with the HTR2C-specific agonist lorcaserin suppressed olanzapine-induced hyperphagia and weight gain. Lorcaserin treatment also improved glucose tolerance in olanzapine-fed mice. Collectively, our studies suggest that olanzapine exerts some of its untoward metabolic effects via antagonism of HTR2C.
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Affiliation(s)
- Caleb C Lord
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | - Steven C Wyler
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | - Rong Wan
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | | | - Newaz Ahmed
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | - Dias Mathew
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | - Syann Lee
- Division of Hypothalamic Research, Department of Internal Medicine, and
| | - Chen Liu
- Division of Hypothalamic Research, Department of Internal Medicine, and.,Department of Neuroscience, and
| | - Joel K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, and.,Department of Pharmacology, UT Southwestern Medical Center, Dallas, Texas, USA
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16
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Fujikawa T, Castorena CM, Pearson M, Kusminski CM, Ahmed N, Battiprolu PK, Kim KW, Lee S, Hill JA, Scherer PE, Holland WL, Elmquist JK. SF-1 expression in the hypothalamus is required for beneficial metabolic effects of exercise. eLife 2016; 5. [PMID: 27874828 PMCID: PMC5119890 DOI: 10.7554/elife.18206] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [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: 05/25/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022] Open
Abstract
Exercise has numerous beneficial metabolic effects. The central nervous system (CNS) is critical for regulating energy balance and coordinating whole body metabolism. However, a role for the CNS in the regulation of metabolism in the context of the exercise remains less clear. Here, using genetically engineered mice we assessed the requirement of steroidogenic factor-1 (SF-1) expression in neurons of the ventromedial hypothalamic nucleus (VMH) in mediating the beneficial effects of exercise on metabolism. We found that VMH-specific deletion of SF-1 blunts (a) the reductions in fat mass, (b) improvements in glycemia, and (c) increases in energy expenditure that are associated with exercise training. Unexpectedly, we found that SF-1 deletion in the VMH attenuates metabolic responses of skeletal muscle to exercise, including induction of PGC-1α expression. Collectively, this evidence suggests that SF-1 expression in VMH neurons is required for the beneficial effects of exercise on metabolism.
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Affiliation(s)
- Teppei Fujikawa
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Carlos M Castorena
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Mackenzie Pearson
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Christine M Kusminski
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Newaz Ahmed
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Pavan K Battiprolu
- Department of Internal Medicine, Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ki Woo Kim
- Department of Pharmacology, Wonju College of Medicine, Yonsei University, Wonju, South Korea.,Department of Global Medical Science, Wonju College of Medicine, Yonsei University, Wonju, South Korea.,Institute of Lifestyle Medicine and Nuclear Receptor Research Consortium, Wonju College of Medicine, Yonsei University, Wonju, South Korea
| | - Syann Lee
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joseph A Hill
- Department of Internal Medicine, Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - William L Holland
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joel K Elmquist
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States.,Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
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Fujikawa T, Castorena CM, Pearson M, Kusminski CM, Ahmed N, Battiprolu PK, Kim KW, Lee S, Hill JA, Scherer PE, Holland WL, Elmquist JK. SF-1 expression in the hypothalamus is required for beneficial metabolic effects of exercise. eLife 2016; 5:e18206. [PMID: 27874828 DOI: 10.7554/elife.15092.001] [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: 05/25/2016] [Accepted: 11/14/2016] [Indexed: 05/26/2023] Open
Abstract
Exercise has numerous beneficial metabolic effects. The central nervous system (CNS) is critical for regulating energy balance and coordinating whole body metabolism. However, a role for the CNS in the regulation of metabolism in the context of the exercise remains less clear. Here, using genetically engineered mice we assessed the requirement of steroidogenic factor-1 (SF-1) expression in neurons of the ventromedial hypothalamic nucleus (VMH) in mediating the beneficial effects of exercise on metabolism. We found that VMH-specific deletion of SF-1 blunts (a) the reductions in fat mass, (b) improvements in glycemia, and (c) increases in energy expenditure that are associated with exercise training. Unexpectedly, we found that SF-1 deletion in the VMH attenuates metabolic responses of skeletal muscle to exercise, including induction of PGC-1α expression. Collectively, this evidence suggests that SF-1 expression in VMH neurons is required for the beneficial effects of exercise on metabolism.
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Affiliation(s)
- Teppei Fujikawa
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Carlos M Castorena
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Mackenzie Pearson
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Christine M Kusminski
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Newaz Ahmed
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Pavan K Battiprolu
- Department of Internal Medicine, Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ki Woo Kim
- Department of Pharmacology, Wonju College of Medicine, Yonsei University, Wonju, South Korea
- Department of Global Medical Science, Wonju College of Medicine, Yonsei University, Wonju, South Korea
- Institute of Lifestyle Medicine and Nuclear Receptor Research Consortium, Wonju College of Medicine, Yonsei University, Wonju, South Korea
| | - Syann Lee
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joseph A Hill
- Department of Internal Medicine, Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, United States
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, United States
| | - William L Holland
- Touchstone Diabetes Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, United States
| | - Joel K Elmquist
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, United States
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, United States
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18
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Liu Y, Huang Y, Lee S, Bookout AL, Castorena CM, Wu H, Gautron L. PPARγ mRNA in the adult mouse hypothalamus: distribution and regulation in response to dietary challenges. Front Neuroanat 2015; 9:120. [PMID: 26388745 PMCID: PMC4558427 DOI: 10.3389/fnana.2015.00120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [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: 06/03/2015] [Accepted: 08/20/2015] [Indexed: 11/13/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that was originally identified as a regulator of peroxisome proliferation and adipocyte differentiation. Emerging evidence suggests that functional PPARγ signaling also occurs within the hypothalamus. However, the exact distribution and identities of PPARγ-expressing hypothalamic cells remains under debate. The present study systematically mapped PPARγ mRNA expression in the adult mouse brain using in situ hybridization histochemistry. PPARγ mRNA was found to be expressed at high levels outside the hypothalamus including the neocortex, the olfactory bulb, the organ of the vasculosum of the lamina terminalis (VOLT), and the subfornical organ. Within the hypothalamus, PPARγ was present at moderate levels in the suprachiasmatic nucleus (SCh) and the ependymal of the 3rd ventricle. In all examined feeding-related hypothalamic nuclei, PPARγ was expressed at very low levels that were close to the limit of detection. Using qPCR techniques, we demonstrated that PPARγ mRNA expression was upregulated in the SCh in response to fasting. Double in situ hybridization further demonstrated that PPARγ was primarily expressed in neurons rather than glia. Collectively, our observations provide a comprehensive map of PPARγ distribution in the intact adult mouse hypothalamus.
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Affiliation(s)
- Yang Liu
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA ; Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China
| | - Ying Huang
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Syann Lee
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Angie L Bookout
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Carlos M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Hua Wu
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China
| | - Laurent Gautron
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
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Sharma N, Wang H, Arias EB, Castorena CM, Cartee GD. Mechanisms for independent and combined effects of calorie restriction and acute exercise on insulin-stimulated glucose uptake by skeletal muscle of old rats. Am J Physiol Endocrinol Metab 2015; 308:E603-12. [PMID: 25670830 PMCID: PMC4385876 DOI: 10.1152/ajpendo.00618.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [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] [Received: 12/30/2014] [Accepted: 02/03/2015] [Indexed: 12/27/2022]
Abstract
Either calorie restriction [CR; consuming 60-65% of ad libitum (AL) intake] or acute exercise can independently improve insulin sensitivity in old age, but their combined effects on muscle insulin signaling and glucose uptake have previously been unknown. Accordingly, we assessed the independent and combined effects of CR (beginning at 14 wk old) and acute exercise (3-4 h postexercise) on insulin signaling and glucose uptake in insulin-stimulated epitrochlearis muscles from 30-mo-old rats. Either CR alone or exercise alone vs. AL sedentary controls induced greater insulin-stimulated glucose uptake. Combined CR and exercise vs. either treatment alone caused an additional increase in insulin-stimulated glucose uptake. Either CR or exercise alone vs. AL sedentary controls increased Akt Ser(473) and Akt Thr(308) phosphorylation. Combined CR and exercise further elevated Akt phosphorylation on both sites. CR alone, but not exercise alone, vs. AL sedentary controls significantly increased Akt substrate of 160 kDa (AS160) Ser(588) and Thr(642) phosphorylation. Combined CR and exercise did not further enhance AS160 phosphorylation. Exercise alone, but not CR alone, modestly increased GLUT4 abundance. Combined CR and exercise did not further elevate GLUT4 content. These results suggest that CR or acute exercise independently increases insulin-stimulated glucose uptake via overlapping (greater Akt phosphorylation) and distinct (greater AS160 phosphorylation for CR, greater GLUT4 for exercise) mechanisms. Our working hypothesis is that greater insulin-stimulated glucose uptake in the combined CR and exercise group vs. CR or exercise alone relies on greater Akt activation, leading to greater phosphorylation of one or more Akt substrates other than AS160.
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Affiliation(s)
- Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan; School of Health Sciences, Central Michigan University, Mount Pleasant, Michigan
| | - Haiyan Wang
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan; College of Physical Education and Health, East China Normal University, Shanghai, China
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Carlos M Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan; and Institute of Gerontology, University of Michigan, Ann Arbor, Michigan
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Castorena CM, Arias EB, Sharma N, Bogan JS, Cartee GD. Fiber type effects on contraction-stimulated glucose uptake and GLUT4 abundance in single fibers from rat skeletal muscle. Am J Physiol Endocrinol Metab 2015; 308:E223-30. [PMID: 25491725 PMCID: PMC4312834 DOI: 10.1152/ajpendo.00466.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [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: 12/17/2022]
Abstract
To fully understand skeletal muscle at the cellular level, it is essential to evaluate single muscle fibers. Accordingly, the major goals of this study were to determine if there are fiber type-related differences in single fibers from rat skeletal muscle for: 1) contraction-stimulated glucose uptake and/or 2) the abundance of GLUT4 and other metabolically relevant proteins. Paired epitrochlearis muscles isolated from Wistar rats were either electrically stimulated to contract (E-Stim) or remained resting (No E-Stim). Single fibers isolated from muscles incubated with 2-deoxy-d-[(3)H]glucose (2-DG) were used to determine fiber type [myosin heavy chain (MHC) isoform protein expression], 2-DG uptake, and abundance of metabolically relevant proteins, including the GLUT4 glucose transporter. E-Stim, relative to No E-Stim, fibers had greater (P < 0.05) 2-DG uptake for each of the isolated fiber types (MHC-IIa, MHC-IIax, MHC-IIx, MHC-IIxb, and MHC-IIb). However, 2-DG uptake for E-Stim fibers was not significantly different among these five fiber types. GLUT4, tethering protein containing a UBX domain for GLUT4 (TUG), cytochrome c oxidase IV (COX IV), and filamin C protein levels were significantly greater (P < 0.05) in MHC-IIa vs. MHC-IIx, MHC-IIxb, or MHC-IIb fibers. TUG and COX IV in either MHC-IIax or MHC-IIx fibers exceeded values for MHC-IIxb or MHC-IIb fibers. GLUT4 levels for MHC-IIax fibers exceeded MHC-IIxb fibers. GLUT4, COX IV, filamin C, and TUG abundance in single fibers was significantly (P < 0.05) correlated with each other. Differences in GLUT4 abundance among the fiber types were not accompanied by significant differences in contraction-stimulated glucose uptake.
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Affiliation(s)
- Carlos M Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan
| | - Jonathan S Bogan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut; Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan; and Institute of Gerontology, University of Michigan, Ann Arbor, Michigan
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21
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Castorena CM, Arias EB, Sharma N, Cartee GD. Effects of a brief high-fat diet and acute exercise on the mTORC1 and IKK/NF-κB pathways in rat skeletal muscle. Appl Physiol Nutr Metab 2014; 40:251-62. [PMID: 25706655 DOI: 10.1139/apnm-2014-0412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
One exercise session can improve subsequent insulin-stimulated glucose uptake by skeletal muscle in healthy and insulin-resistant individuals. Our first aim was to determine whether a brief (2 weeks) high-fat diet (HFD) that caused muscle insulin resistance would activate the mammalian target of rapamycin complex 1 (mTORC1) and/or inhibitor of κB kinase/nuclear factor κB (IKK/NF-κB) pathways, which are potentially linked to induction of insulin resistance. Our second aim was to determine whether acute exercise that improved insulin-stimulated glucose uptake by muscles would attenuate activation of these pathways. We compared HFD-fed rats with rats fed a low-fat diet (LFD). Some animals from each diet group were sedentary and others were studied 3 h postexercise, when insulin-stimulated glucose uptake was increased. The results did not provide evidence that brief HFD activated either the mTORC1 (including phosphorylation of mTOR(Ser2448), TSC2(Ser939), p70S6K(Thr412), and RPS6(Ser235/236)) or the IKK/NF-κB (including abundance of IκBα or phosphorylation of NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)) pathway in insulin-resistant muscles. Exercise did not oppose the activation of either pathway, as evidenced by no attenuation of phosphorylation of key proteins in the IKK/NF-κB pathway (NF-κB(Ser536), IKKα/β(Ser177/181), and IκB(Ser32)), unaltered IκBα abundance, and no attenuation of phosphorylation of key proteins in the mTORC1 pathway (mTOR(Ser2448), TSC2(Ser939), and RPS6(Ser235/236)). Instead, exercise induced greater phosphorylation of 2 proteins of the mTORC1 pathway (PRAS40(Thr246) and p70S6K(Thr412)) in insulin-stimulated muscles, regardless of diet. Insulin resistance induced by a brief HFD was not attributable to greater activation of the mTORC1 or the IKK/NF-κB pathway in muscle, and exercise-induced improvement in insulin sensitivity was not attributable to attenuated activation of these pathways in muscle.
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Affiliation(s)
- Carlos M Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI 48109-2214, USA
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22
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Castorena CM, Arias EB, Sharma N, Cartee GD. Postexercise improvement in insulin-stimulated glucose uptake occurs concomitant with greater AS160 phosphorylation in muscle from normal and insulin-resistant rats. Diabetes 2014; 63:2297-308. [PMID: 24608437 PMCID: PMC4066340 DOI: 10.2337/db13-1686] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [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] [Indexed: 12/17/2022]
Abstract
Earlier research on rats with normal insulin sensitivity demonstrated that acute exercise increased insulin-stimulated glucose uptake (GU) concomitant with greater phosphorylation of Akt substrate of 160 kDa (pAS160). Because mechanisms for exercise effects on GU in insulin-resistant muscle are unknown, our primary objective was to assess insulin-stimulated GU, proximal insulin signaling (insulin receptor [IR] tyrosine phosphorylation, IR substrate 1-phosphatidylinositol-3-kinase, and Akt phosphorylation and activity), and pAS160 in muscles from acutely exercised (one session) and sedentary rats fed either chow (low-fat diet [LFD]; normal insulin sensitivity) or a high-fat diet (HFD; for 2 weeks, insulin-resistant). At 3 h postexercise (3hPEX), isolated epitrochlearis muscles were used for insulin-stimulated GU and insulin signaling measurements. Although exercise did not enhance proximal signaling in either group, insulin-stimulated GU at 3hPEX exceeded respective sedentary control subjects (Sedentary) in both diet groups. Furthermore, insulin-stimulated GU for LFD-3hPEX was greater than HFD-3hPEX values. For HFD-3hPEX muscles, pAS160 exceeded HFD-Sedentary, but in muscle from LFD-3hPEX rats, pAS160 was greater still than HFD-3hPEX values. These results implicated pAS160 as a potential determinant of the exercise-induced elevation in insulin-stimulated GU for each diet group and also revealed pAS160 as a possible mediator of greater postexercise GU of insulin-stimulated muscles from the insulin-sensitive versus insulin-resistant group.
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Affiliation(s)
- Carlos M Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MISchool of Health Sciences, Central Michigan University, Mount Pleasant, MI
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MIDepartment of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MIInstitute of Gerontology, University of Michigan, Ann Arbor, MI
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Löffler MG, Birkenfeld AL, Philbrick KM, Belman JP, Habtemichael EN, Booth CJ, Castorena CM, Choi CS, Jornayvaz FR, Gassaway BM, Lee HY, Cartee GD, Philbrick W, Shulman GI, Samuel VT, Bogan JS. Enhanced fasting glucose turnover in mice with disrupted action of TUG protein in skeletal muscle. J Biol Chem 2013; 288:20135-50. [PMID: 23744065 DOI: 10.1074/jbc.m113.458075] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [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: 11/06/2022] Open
Abstract
Insulin stimulates glucose uptake in 3T3-L1 adipocytes in part by causing endoproteolytic cleavage of TUG (tether containing a ubiquitin regulatory X (UBX) domain for glucose transporter 4 (GLUT4)). Cleavage liberates intracellularly sequestered GLUT4 glucose transporters for translocation to the cell surface. To test the role of this regulation in muscle, we used mice with muscle-specific transgenic expression of a truncated TUG fragment, UBX-Cter. This fragment causes GLUT4 translocation in unstimulated 3T3-L1 adipocytes. We predicted that transgenic mice would have GLUT4 translocation in muscle during fasting. UBX-Cter expression caused depletion of PIST (PDZ domain protein interacting specifically with TC10), which transmits an insulin signal to TUG. Whereas insulin stimulated TUG proteolysis in control muscles, proteolysis was constitutive in transgenic muscles. Fasting transgenic mice had decreased plasma glucose and insulin concentrations compared with controls. Whole-body glucose turnover was increased during fasting but not during hyperinsulinemic clamp studies. In muscles with the greatest UBX-Cter expression, 2-deoxyglucose uptake during fasting was similar to that in control muscles during hyperinsulinemic clamp studies. Fasting transgenic mice had increased muscle glycogen, and GLUT4 targeting to T-tubule fractions was increased 5.7-fold. Whole-body oxygen consumption (VO2), carbon dioxide production (VCO2), and energy expenditure were increased by 12-13%. After 3 weeks on a high fat diet, the decreased fasting plasma glucose in transgenic mice compared with controls was more marked, and increased glucose turnover was not observed; the transgenic mice continued to have an increased metabolic rate. We conclude that insulin stimulates TUG proteolysis to translocate GLUT4 in muscle, that this pathway impacts systemic glucose homeostasis and energy metabolism, and that the effects of activating this pathway are maintained during high fat diet-induced insulin resistance in mice.
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Affiliation(s)
- Michael G Löffler
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA
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Sharma N, Sequea DA, Castorena CM, Arias EB, Qi NR, Cartee GD. Heterogeneous effects of calorie restriction on in vivo glucose uptake and insulin signaling of individual rat skeletal muscles. PLoS One 2013; 8:e65118. [PMID: 23755179 PMCID: PMC3670927 DOI: 10.1371/journal.pone.0065118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [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] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/22/2013] [Indexed: 11/19/2022] Open
Abstract
Calorie restriction (CR) (consuming ~60% of ad libitum, AL, intake) improves whole body insulin sensitivity and enhances insulin-stimulated glucose uptake by isolated skeletal muscles. However, little is known about CR-effects on in vivo glucose uptake and insulin signaling in muscle. Accordingly, 9-month-old male AL and CR (initiated when 3-months-old) Fischer 344 x Brown Norway rats were studied using a euglycemic-hyperinsulinemic clamp with plasma insulin elevated to a similar level (~140 µU/ml) in each diet group. Glucose uptake (assessed by infusion of [(14)C]-2-deoxyglucose, 2-DG), phosphorylation of key insulin signaling proteins (insulin receptor, Akt and Akt substrate of 160 kDa, AS160), abundance of GLUT4 and hexokinase proteins, and muscle fiber type composition (myosin heavy chain, MHC, isoform percentages) were determined in four predominantly fast-twitch (epitrochlearis, gastrocnemius, tibialis anterior, plantaris) and two predominantly slow-twitch (soleus, adductor longus) muscles. CR did not result in greater GLUT4 or hexokinase abundance in any of the muscles, and there were no significant diet-related effects on percentages of MHC isoforms. Glucose infusion was greater for CR versus AL rats (P<0.05) concomitant with significantly (P<0.05) elevated 2-DG uptake in 3 of the 4 fast-twitch muscles (epitrochlearis, gastrocnemius, tibialis anterior), without a significant diet-effect on 2-DG uptake by the plantaris or either slow-twitch muscle. Each of the muscles with a CR-related increase in 2-DG uptake was also characterized by significant (P<0.05) increases in phosphorylation of both Akt and AS160. Among the 3 muscles without a CR-related increase in glucose uptake, only the soleus had significant (P<0.05) CR-related increases in Akt and AS160 phosphorylation. The current data revealed that CR leads to greater whole body glucose disposal in part attributable to elevated in vivo insulin-stimulated glucose uptake by fast-twitch muscles. The results also demonstrated that CR does not uniformly enhance either insulin signaling or insulin-stimulated glucose uptake in all muscles in vivo.
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Affiliation(s)
- Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Donel A. Sequea
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Carlos M. Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Edward B. Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Nathan R. Qi
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gregory D. Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Xiao Y, Sharma N, Arias EB, Castorena CM, Cartee GD. A persistent increase in insulin-stimulated glucose uptake by both fast-twitch and slow-twitch skeletal muscles after a single exercise session by old rats. Age (Dordr) 2013; 35:573-582. [PMID: 22286902 PMCID: PMC3636414 DOI: 10.1007/s11357-012-9383-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [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: 10/11/2011] [Accepted: 01/12/2012] [Indexed: 05/31/2023]
Abstract
Exercise has been demonstrated to enhance subsequent insulin-stimulated glucose uptake (GU) by predominantly type II (fast-twitch) muscle of old rats, but previous research has not evaluated exercise effects on GU by type I (slow-twitch) muscle from old rats. Accordingly, we studied male Fischer 344/Brown Norway rats (24 months old) and determined GU (0, 100, 200, and 5,000 μU/ml insulin) of isolated soleus (predominantly type I) and epitrochlearis (predominantly type II) muscles after one exercise session. Epitrochlearis (100, 200, and 5,000 μU/ml insulin) and soleus (100 and 200 μU/ml insulin) GU were greater at 3-h postexercise vs. age-matched sedentary controls. Insulin receptor tyrosine phosphorylation (Tyr1162/1163) was unaltered by exercise in either muscle. Akt phosphorylation (pAkt) was greater for exercised vs. sedentary rats in the epitrochlearis (Ser473 and Thr308 with 100 and 200 μU/ml, respectively) and soleus (Ser473 with 200 μU/ml). AS160 phosphorylation (pAS160) was greater for exercised vs. sedentary rats in the epitrochlearis (Thr642 with 100 μU/ml), but not the soleus. Exercised vs. sedentary rats did not differ for total protein abundance of insulin receptor, Akt, AS160, or GLUT4 in either muscle. These results demonstrate that both predominantly type I and type II muscles from old rats are susceptible to exercise-induced improvement in insulin-mediated GU by mechanisms that are independent of enhanced insulin receptor tyrosine phosphorylation or altered abundance of important signaling proteins or GLUT4. Exercise-induced elevation in pAkt, and possibly pAS160, may contribute to this effect in the epitrochlearis of old rats, but other mechanisms are likely important for the soleus.
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Affiliation(s)
- Yuanyuan Xiao
- />Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214 USA
| | - Naveen Sharma
- />Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214 USA
| | - Edward B. Arias
- />Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214 USA
| | - Carlos M. Castorena
- />Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214 USA
| | - Gregory D. Cartee
- />Muscle Biology Laboratory, School of Kinesiology, University of Michigan, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214 USA
- />Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109 USA
- />Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109 USA
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Sharma N, Sequea DA, Castorena CM, Qi N, Cartee GD. Calorie restriction effects on insulin signaling and glucose uptake in multiple insulin‐stimulated rat skeletal muscles in vivo. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1202.9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Sharma N, Castorena CM, Cartee GD. Greater insulin sensitivity in calorie restricted rats occurs with unaltered circulating levels of several important myokines and cytokines. Nutr Metab (Lond) 2012; 9:90. [PMID: 23067400 PMCID: PMC3541154 DOI: 10.1186/1743-7075-9-90] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 10/05/2012] [Indexed: 12/31/2022] Open
Abstract
Calorie restriction (CR; ~60% of ad libitum, AL intake) has been associated with substantial alterations in body composition and insulin sensitivity. Recently, several proteins that are secreted by nontraditional endocrine tissues, including skeletal muscle and other tissues, have been discovered to modulate energy metabolism, body composition, and insulin sensitivity. The aim of this study was to characterize the influence of CR by rats on plasma levels of six of these newly recognized metabolic hormones (BDNF, FGF21, IL-1β, myonectin, myostatin, and irisin). Body composition of 9-month old male Fischer-344/Brown Norway rats (AL and CR groups) was determined by nuclear magnetic resonance. Blood sampled from the carotid artery of unanesthetized rats was used to measure concentrations of glucose and plasma proteins. As expected, CR versus AL rats had significantly altered body composition (reduced percent fat mass, increased percent lean mass) and significantly improved insulin sensitivity (based on the homeostasis model assessment-estimated insulin resistance index). Also consistent with previous reports, CR compared to AL rats had significantly greater plasma levels of adiponectin and corticosterone. However, there were no significant diet-related differences in plasma levels of BDNF, FGF21, IL-1β, myonectin, myostatin, or irisin. In conclusion, these results indicate that alterations in plasma concentration of these six secreted proteins are not essential for the CR-related improvement in insulin sensitivity in rats.
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Affiliation(s)
- Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI, USA.
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Sharma N, Castorena CM, Cartee GD. Tissue-specific responses of IGF-1/insulin and mTOR signaling in calorie restricted rats. PLoS One 2012; 7:e38835. [PMID: 22701721 PMCID: PMC3368930 DOI: 10.1371/journal.pone.0038835] [Citation(s) in RCA: 35] [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] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 05/15/2012] [Indexed: 12/22/2022] Open
Abstract
Moderate calorie restriction (CR) (∼60% of ad libitum, AL, intake) has been associated with numerous favorable physiological outcomes in many species, and the insulin/IGF-1 and mTOR signaling pathways have each been proposed as potential mediators for many of CR's bioeffects. However, few studies have assessed the widely held idea that CR induces the down-regulation of the insulin/IGF-1 and/or mTOR pathways in multiple tissues. Accordingly, we analyzed the phosphorylation status of 11 key signaling proteins from the insulin/IGF-1 (IRTyr1162/1163, IGF-1RTyr1135/1136, IRS-1Ser312, PTENSer380, AktSer473, GSK3αSer21, GSK3βSer9) and mTOR (TSC2Ser939, mTORSer2448, P70S6KThr412, RPS6Ser235/236) pathways in 11 diverse tissues [liver, kidney, lung, aorta, two brain regions (cortex and cerebellum), and two slow-twitch and three fast-twitch skeletal muscles] from 9-month-old male AL and CR Fischer 344 x Brown Norway rats. The rats were studied under two conditions: with endogenous insulin levels (i.e., AL>CR) and with insulin infused during a hyperinsulinemic-euglycemic clamp so that plasma insulin concentrations were matched between the two diet groups. The most striking and consistent effect of CR was greater pAkt in 3 of the 5 skeletal muscles of CR vs. AL rats. There were no significant CR effects on the mTOR signaling pathway and no evidence that CR caused a general attenuation of mTOR signaling across the tissues studied. Rather than supporting the premise of a global downregulation of insulin/IGF-1 and/or mTOR signaling in many tissues, the current results revealed clear tissue-specific CR effects for the insulin signaling pathway without CR effects on the mTOR signaling pathway.
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Affiliation(s)
- Naveen Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Carlos M. Castorena
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Gregory D. Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Castorena CM, Mackrell JG, Bogan JS, Kanzaki M, Cartee GD. Clustering of GLUT4, TUG, and RUVBL2 protein levels correlate with myosin heavy chain isoform pattern in skeletal muscles, but AS160 and TBC1D1 levels do not. J Appl Physiol (1985) 2011; 111:1106-17. [PMID: 21799128 DOI: 10.1152/japplphysiol.00631.2011] [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] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Skeletal muscle is a heterogeneous tissue. To further elucidate this heterogeneity, we probed relationships between myosin heavy chain (MHC) isoform composition and abundance of GLUT4 and four other proteins that are established or putative GLUT4 regulators [Akt substrate of 160 kDa (AS160), Tre-2/Bub2/Cdc 16-domain member 1 (TBC1D1), Tethering protein containing an UBX-domain for GLUT4 (TUG), and RuvB-like protein two (RUVBL2)] in 12 skeletal muscles or muscle regions from Wistar rats [adductor longus, extensor digitorum longus, epitrochlearis, gastrocnemius (mixed, red, and white), plantaris, soleus, tibialis anterior (red and white), tensor fasciae latae, and white vastus lateralis]. Key results were 1) significant differences found among the muscles (range of muscle expression values) for GLUT4 (2.5-fold), TUG (1.7-fold), RUVBL2 (2.0-fold), and TBC1D1 (2.7-fold), but not AS160; 2) significant positive correlations for pairs of proteins: GLUT4 vs. TUG (R = 0.699), GLUT4 vs. RUVBL2 (R = 0.613), TUG vs. RUVBL2 (R = 0.564), AS160 vs. TBC1D1 (R = 0.293), and AS160 vs. TUG (R = 0.246); 3) significant positive correlations for %MHC-I: GLUT4 (R = 0.460), TUG (R = 0.538), and RUVBL2 (R = 0.511); 4) significant positive correlations for %MHC-IIa: GLUT4 (R = 0.293) and RUVBL2 (R = 0.204); 5) significant negative correlations for %MHC-IIb vs. GLUT4 (R = -0.642), TUG (R = -0.626), and RUVBL2 (R = -0.692); and 6) neither AS160 nor TBC1D1 significantly correlated with MHC isoforms. In 12 rat muscles, GLUT4 abundance tracked with TUG and RUVBL2 and correlated with MHC isoform expression, but was unrelated to AS160 or TBC1D1. Our working hypothesis is that some of the mechanisms that regulate GLUT4 abundance in rat skeletal muscle also influence TUG and RUVBL2 abundance.
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Affiliation(s)
- Carlos M Castorena
- Muscle Biology Laboratory, Univ. of Michigan, School of Kinesiology, Ann Arbor, MI 48109-2214, USA
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Sequea DA, Sharma N, Castorena CM, Qi N, Cartee GD. Calorie Restriction Increases In Vivo Glucose Uptake and Insulin Signaling in Rat Skeletal Muscle. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.lb591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Nathan Qi
- Internal MedicineUniversity of MichiganAnn ArborMI
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Schweitzer GG, Castorena CM, Hamada T, Funai K, Arias EB, Cartee GD. The B2 receptor of bradykinin is not essential for the post-exercise increase in glucose uptake by insulin-stimulated mouse skeletal muscle. Physiol Res 2011; 60:511-9. [PMID: 21401298 DOI: 10.33549/physiolres.932085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bradykinin can enhance skeletal muscle glucose uptake (GU), and exercise increases both bradykinin production and muscle insulin sensitivity, but bradykinin's relationship with post-exercise insulin action is uncertain. Our primary aim was to determine if the B2 receptor of bradykinin (B2R) is essential for the post-exercise increase in GU by insulin-stimulated mouse soleus muscles. Wildtype (WT) and B2R knockout (B2RKO) mice were sedentary or performed 60 minutes of treadmill exercise. Isolated soleus muscles were incubated with [³H]-2-deoxyglucose +/-insulin (60 or 100 microU/ml). GU tended to be greater for WT vs. B2RKO soleus with 60 microU/ml insulin (P=0.166) and was significantly greater for muscles with 100 microU/ml insulin (P<0.05). Both genotypes had significant exercise-induced reductions (P<0.05) in glycemia and insulinemia, and the decrements for glucose (approximately 14 %) and insulin (approximately 55 %) were similar between genotypes. GU tended to be greater for exercised vs. sedentary soleus with 60 microU/ml insulin (P=0.063) and was significantly greater for muscles with 100 microU/ml insulin (P<0.05). There were no significant interactions between genotype and exercise for blood glucose, plasma insulin or GU. These results indicate that the B2R is not essential for the exercise-induced decrements in blood glucose or plasma insulin or for the post-exercise increase in GU by insulin-stimulated mouse soleus muscle.
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Affiliation(s)
- G G Schweitzer
- Muscle Biology Laboratory, University of Michigan, School of Kinesiology, Ann Arbor, MI, USA
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Castorena CM, MacKrell JG, Kanzaki M, Bogan JS, Cartee GD. GLUT4, TBC1D1, TBC1D4, TUG and RUVBL2: Relationships with Each Other and Rat Muscle Fiber Type. Med Sci Sports Exerc 2010. [DOI: 10.1249/01.mss.0000389501.47832.4f] [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] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Funai K, Schweitzer GG, Castorena CM, Kanzaki M, Cartee GD. In vivo exercise followed by in vitro contraction additively elevates subsequent insulin-stimulated glucose transport by rat skeletal muscle. Am J Physiol Endocrinol Metab 2010; 298:E999-1010. [PMID: 20179245 PMCID: PMC2867374 DOI: 10.1152/ajpendo.00758.2009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [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: 11/22/2022]
Abstract
The cellular mechanisms whereby prior exercise enhances insulin-stimulated glucose transport (GT) are not well understood. Previous studies suggested that a prolonged increase in phosphorylation of Akt substrate of 160 kDa (AS160) may be important for the postexercise increase in insulin sensitivity. In the current study, the effects of in vivo exercise and in vitro contraction on subsequent insulin-stimulated GT were studied separately and together. Consistent with results from previous studies, prior exercise resulted in an increase in AS160 (642)Thr phosphorylation immediately after exercise in rat epitrochlearis muscles, and this increase remained 3 h postexercise concomitant with enhanced insulin-stimulated GT. For experiments with in vitro contraction, isolated rat epitrochlearis muscles were electrically stimulated to contract in the presence or absence of rat serum. As expected, insulin-stimulated GT measured 3 h after electrical stimulation in serum, but not after electrical stimulation without serum, exceeded resting controls. Immediately after electrical stimulation with or without serum, phosphorylation of both AS160 (detected by phospho-Akt substrate, PAS, antibody, or phospho-(642)Thr antibody) and its paralog TBC1D1 (detected by phospho-(237)Ser antibody) was increased. However, both AS160 and TBC1D1 phosphorylation had reversed to resting values at 3 h poststimulation with or without serum. Increasing the amount of exercise (from 1 to 2 h) or electrical stimulation (from 5 to 10 tetani) did not further elevate insulin-stimulated GT. In contrast, the combination of prior exercise and electrical stimulation had an additive effect on the subsequent increase in insulin-stimulated GT, suggesting that these exercise and electrical stimulation protocols may amplify insulin-stimulated GT through distinct mechanisms, with a persistent increase in AS160 phosphorylation potentially important for increased insulin sensitivity after exercise, but not after in vitro contraction.
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Affiliation(s)
- Katsuhiko Funai
- University of Michigan, School of Kinesiology, Muscle Biology Laboratory, 401 Washtenaw Ave., Ann Arbor, MI 48109-2214, USA
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