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Grant AD, Wilsterman K, Smarr BL, Kriegsfeld LJ. Evidence for a Coupled Oscillator Model of Endocrine Ultradian Rhythms. J Biol Rhythms 2018; 33:475-496. [PMID: 30132387 DOI: 10.1177/0748730418791423] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Whereas long-period temporal structures in endocrine dynamics have been well studied, endocrine rhythms on the scale of hours are relatively unexplored. The study of these ultradian rhythms (URs) has remained nascent, in part, because a theoretical framework unifying ultradian patterns across systems has not been established. The present overview proposes a conceptual coupled oscillator network model of URs in which oscillating hormonal outputs, or nodes, are connected by edges representing the strength of node-node coupling. We propose that variable-strength coupling exists both within and across classic hormonal axes. Because coupled oscillators synchronize, such a model implies that changes across hormonal systems could be inferred by surveying accessible nodes in the network. This implication would at once simplify the study of URs and open new avenues of exploration into conditions affecting coupling. In support of this proposed framework, we review mammalian evidence for (1) URs of the gut-brain axis and the hypothalamo-pituitary-thyroid, -adrenal, and -gonadal axes, (2) UR coupling within and across these axes; and (3) the relation of these URs to body temperature. URs across these systems exhibit behavior broadly consistent with a coupled oscillator network, maintaining both consistent URs and coupling within and across axes. This model may aid the exploration of mammalian physiology at high temporal resolution and improve the understanding of endocrine system dynamics within individuals.
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Affiliation(s)
- Azure D Grant
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California
| | - Kathryn Wilsterman
- Department of Integrative Biology, University of California, Berkeley, California
| | - Benjamin L Smarr
- Department of Psychology, University of California, Berkeley, California
| | - Lance J Kriegsfeld
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California.,Department of Psychology, University of California, Berkeley, California
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Development and initial characterization of a novel ghrelin receptor CRISPR/Cas9 knockout wistar rat model. Int J Obes (Lond) 2018; 43:344-354. [PMID: 29453460 PMCID: PMC6066458 DOI: 10.1038/s41366-018-0013-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/11/2017] [Accepted: 12/10/2017] [Indexed: 01/18/2023]
Abstract
Background/objectives Ghrelin, a stomach-derived hormone implicated in numerous behaviors including feeding, reward, stress, and addictive behaviors, acts through binding to the growth hormone secretagogue receptor (GHSR). Here, we present the development, verification and initial characterization of a novel GHSR knockout (KO) Wistar rat model created with CRISPR genome editing. Methods Using CRISPR/Cas9, we developed a GHSR knockout (KO) in a Wistar background. Loss of GHSR mRNA expression was histologically verified using RNAscope in wild-type WT (n = 2) and KO (n = 2) rats. We tested the effects of intraperitoneal acyl-ghrelin administration on food consumption and plasma growth hormone (GH) concentrations in WT (n = 8) and KO (n = 8) rats. We also analyzed locomotion, food consumption, and body fat composition in these animals. Body weight was monitored from early development to adulthood. Results The RNAscope analysis revealed an abundance of GHSR mRNA expression in the hypothalamus, midbrain, and hippocampus in WTs, and no observed probe binding in KOs. Ghrelin administration increased plasma GH levels (p = 0.0067) and food consumption (p = 0.0448) in WT rats but not KOs. KO rats consumed less food overall at basal conditions and weighed significantly less compared with WTs throughout development (p = 0.0001). Compared with WTs, KOs presented higher concentrations of brown adipose tissue (BAT) (p = 0.0322). Conclusions We have verified GHSR deletion in our KO model using histological, physiological, neuroendocrinological and behavioral measures. Our findings indicate that GHSR deletion in rats is not only associated with a lack of response to ghrelin, but also associated with decreases in daily food consumption and body growth, and increases in BAT. This GHSR KO Wistar rat model provides a novel tool for studying the role of the ghrelin system in obesity and in a wide range of medical and neuropsychiatric disorders.
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Wei Q, Lee JH, Wang H, Bongmba OYN, Wu CS, Pradhan G, Sun Z, Chew L, Bajaj M, Chan L, Chapkin RS, Chen MH, Sun Y. Adiponectin is required for maintaining normal body temperature in a cold environment. BMC PHYSIOLOGY 2017; 17:8. [PMID: 29058611 PMCID: PMC5651620 DOI: 10.1186/s12899-017-0034-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 10/12/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND Thermogenic impairment promotes obesity and insulin resistance. Adiponectin is an important regulator of energy homeostasis. While many beneficial metabolic effects of adiponectin resemble that of activated thermogenesis, the role of adiponectin in thermogenesis is not clear. In this study, we investigated the role of adiponectin in thermogenesis using adiponectin-null mice (Adipoq -/-). METHODS Body composition was measured using EchoMRI. Metabolic parameters were determined by indirect calorimetry. Insulin sensitivity was evaluated by glucose- and insulin- tolerance tests. Core body temperature was measured by a TH-8 temperature monitoring system. Gene expression was assessed by real-time PCR and protein levels were analyzed by Western blotting and immunohistochemistry. The mitochondrial density of brown adipose tissue was quantified by calculating the ratio of mtDNA:total nuclear DNA. RESULTS Under normal housing temperature of 24 °C and ad libitum feeding condition, the body weight, body composition, and metabolic profile of Adipoq -/- mice were unchanged. Under fasting condition, Adipoq -/- mice exhibited reduced energy expenditure. Conversely, under cold exposure, Adipoq -/- mice exhibited reduced body temperature, and the expression of thermogenic regulatory genes was significantly reduced in brown adipose tissue (BAT) and subcutaneous white adipose tissue (WAT). Moreover, we observed that mitochondrial content was reduced in BAT and subcutaneous WAT, and the expression of mitochondrial fusion genes was decreased in BAT of Adipoq -/- mice, suggesting that adiponectin ablation diminishes mitochondrial biogenesis and altered mitochondrial dynamics. Our study further revealed that adiponectin deletion suppresses adrenergic activation, and down-regulates β3-adrenergic receptor, insulin signaling, and the AMPK-SIRT1 pathway in BAT. CONCLUSIONS Our findings demonstrate that adiponectin is an essential regulator of thermogenesis, and adiponectin is required for maintaining body temperature under cold exposure.
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Affiliation(s)
- Qiong Wei
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.,Division of Endocrinology, Zhongda hospital, Southeast University, Nanjing, Jiangsu Province, People's Republic of China, 210002
| | - Jong Han Lee
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.,College of Pharmacy, Gachon University, Incheon, 21936, South Korea
| | - Hongying Wang
- Department of Nutrition and Food Science, Texas A&M University, 214D Cater-Mattil; 2253 TAMU, College Station, TX, 77843, USA.,Laboratory of Lipid & Glucose Metabolism, The First Affiliated Hospital of Chongqing Medical University, Chongqing, Sichuan province, People's Republic of China, 400016
| | - Odelia Y N Bongmba
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Chia-Shan Wu
- Department of Nutrition and Food Science, Texas A&M University, 214D Cater-Mattil; 2253 TAMU, College Station, TX, 77843, USA
| | - Geetali Pradhan
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Zilin Sun
- Division of Endocrinology, Zhongda hospital, Southeast University, Nanjing, Jiangsu Province, People's Republic of China, 210002
| | - Lindsey Chew
- Institute of Biosciences and Technology, Houston, TX, 77030, USA
| | - Mandeep Bajaj
- Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Lawrence Chan
- Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Robert S Chapkin
- Department of Nutrition and Food Science, Texas A&M University, 214D Cater-Mattil; 2253 TAMU, College Station, TX, 77843, USA
| | - Miao-Hsueh Chen
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Yuxiang Sun
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA. .,Department of Nutrition and Food Science, Texas A&M University, 214D Cater-Mattil; 2253 TAMU, College Station, TX, 77843, USA. .,Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA.
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Caron A, Richard D. Neuronal systems and circuits involved in the control of food intake and adaptive thermogenesis. Ann N Y Acad Sci 2016; 1391:35-53. [PMID: 27768821 DOI: 10.1111/nyas.13263] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 08/18/2016] [Accepted: 08/24/2016] [Indexed: 12/27/2022]
Abstract
With the still-growing prevalence of obesity worldwide, major efforts are made to understand the various behavioral, environmental, and genetic factors that promote excess fat gain. Obesity results from an imbalance between energy intake and energy expenditure, which emphasizes the importance of deciphering the mechanisms behind energy balance regulation to understand its physiopathology. The control of energy balance is assured by brain systems/circuits capable of generating adequate ingestive and thermogenic responses to maintain the stability of energy reserves, which implies a proper integration of the homeostatic signals that inform about the status of the energy stores. In this article, we overview the organization and functionality of key neuronal circuits or pathways involved in the control of food intake and energy expenditure. We review the role of the corticolimbic (executive and reward) and autonomic systems that integrate their activities to regulate energy balance. We also describe the mechanisms and pathways whereby homeostatic sensing is achieved in response to variations of homeostatic hormones, such as leptin, insulin, and ghrelin, while putting some emphasis on the prominent importance of the mechanistic target of the rapamycin signaling pathway in coordinating the homeostatic sensing process.
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Affiliation(s)
- Alexandre Caron
- Institut Universitaire de Cardiologie et de Pneumologie de Quebec and Faculty of Medicine, Department of Medicine, Université Laval, Quebec City, Quebec, Canada
| | - Denis Richard
- Institut Universitaire de Cardiologie et de Pneumologie de Quebec and Faculty of Medicine, Department of Medicine, Université Laval, Quebec City, Quebec, Canada
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The suppression of ghrelin signaling mitigates age‐associated thermogenic impairment. Aging (Albany NY) 2015; 6:1019-32. [PMID: 25543537 DOI: 10.18632/aging.100706] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Aging is associated with severe thermogenic impairment, which contributes to obesity and diabetes in aging. We previously reported that ablation of the ghrelin receptor, growth hormone secretagogue receptor (GHS‐R), attenuates age‐associated obesity and insulin resistance. Ghrelin and obestatin are derived from the same preproghrelin gene. Here we showed that in brown adipocytes, ghrelin decreases the expression of thermogenic regulator but obestatin increases it, thus showing the opposite effects. We also found that during aging, plasma ghrelin and GHS‐R expression in brown adipose tissue (BAT) are increased, but plasma obestatin is unchanged. Increased plasma ghrelin and unchanged obestatin during aging may lead to an imbalance of thermogenic regulation, which may in turn exacerbate thermogenic impairment in aging. Moreover, we found that GHS‐R ablation activates thermogenic signaling, enhances insulin activation, increases mitochondrial biogenesis, and improves mitochondrial dynamics of BAT. In addition, we detected increased norepinephrine in the circulation, and observed that GHS‐R knockdown in brown adipocytes directly stimulates thermogenic activity, suggesting that GHS‐R regulates thermogenesis via both central and peripheral mechanisms.Collectively, our studies demonstrate that ghrelin signaling is an important thermogenic regulator in aging. Antagonists of GHS‐R may serve as unique anti‐obesity agents, combating obesity by activating thermogenesis.
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Siegl D, Midura EF, Annecke T, Conzen P, Caldwell CC, Tschoep J. The effect of ghrelin upon the early immune response in lean and obese mice during sepsis. PLoS One 2015; 10:e0122211. [PMID: 25844479 PMCID: PMC4386814 DOI: 10.1371/journal.pone.0122211] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 02/19/2015] [Indexed: 12/02/2022] Open
Abstract
Introduction It is well established that obesity-related hormones can have modulatory effects associated with the immune response. Ghrelin, a hormone mainly derived from endocrine cells of the gastric mucosa, regulates appetite, energy expenditure and body weight counteracting leptin, a hormone mainly derived from adipocytes. Additionally, receptors of both have been detected on immune cells and demonstrated an immune regulatory function during sepsis. Methods In the present study, the effect of peripheral ghrelin administration on early immune response and survival was investigated with lean mice and mice with diet-induced obesity using cecal ligation and puncture to induce sepsis. Results In the obese group, we found that ghrelin treatment improved survival, ameliorated hypothermia, and increased hyperleptinemia as compared to the lean controls. We also observed that ghrelin treatment divergently regulated serum IL-1ß and TNF-α concentrations in both lean and obese septic mice. Ghrelin treatment initially decreased but later resulted in increased bacteriaemia in lean mice while having no impact upon obese mice. Similarly, ghrelin treatment increased early neutrophil oxidative burst while causing a decrease 48 hours after sepsis inducement. Conclusion In conclusion, as the immune response to sepsis temporally changes, ghrelin treatment differentially mediates this response. Specifically, we observed that ghrelin conferred protective effects during the early phase of sepsis, but during the later phase deteriorated immune response and outcome. These adverse effects were more pronounced upon lean mice as compared to obese mice.
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Affiliation(s)
- Daniel Siegl
- Walter-Brendel-Centre of Experimental Medicine, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Emily F. Midura
- Division of Research, Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Thorsten Annecke
- Department of Anaesthesiology and Intensive Care Medicine, University Hospital of Cologne, Cologne, Germany
| | - Peter Conzen
- Department of Anaesthesiology, University Hospital Munich (LMU), Munich, Germany
| | - Charles C. Caldwell
- Division of Research, Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Johannes Tschoep
- Department of Anaesthesiology, University Hospital Munich (LMU), Munich, Germany
- * E-mail:
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