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Wargent ET, Ahmad SJS, Lu QR, Kostenis E, Arch JRS, Stocker CJ. Leanness and Low Plasma Leptin in GPR17 Knockout Mice Are Dependent on Strain and Associated With Increased Energy Intake That Is Not Suppressed by Exogenous Leptin. Front Endocrinol (Lausanne) 2021; 12:698115. [PMID: 34646232 PMCID: PMC8503278 DOI: 10.3389/fendo.2021.698115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 08/20/2021] [Indexed: 11/16/2022] Open
Abstract
Previous studies have shown that agonists of GPR17 stimulate, while antagonists inhibit feeding. However, whole body knockout of GPR17 in mice of the C57Bl/6 strain did not affect energy balance, whereas selective knockout in oligodendrocytes or pro-opiomelanocortin neurons provided protection from high fat diet-induced obesity and impaired glucose homeostasis. We reasoned that whole body knockout of GPR17 in mice of the 129 strain might elicit more marked effects because the 129 strain is more susceptible than the C57Bl/6 strain to increased sympathetic activity and less susceptible to high fat diet-induced obesity. Consistent with this hypothesis, compared to wild-type mice, and when fed on either a chow or a high fat diet, GPR17 -/- mice of the 129 strain displayed increased expression of uncoupling protein-1 in white adipose tissue, lower body weight and fat content, reduced plasma leptin, non-esterified fatty acids and triglycerides, and resistance to high fat diet-induced glucose intolerance. Not only energy expenditure, but also energy intake was raised. Administration of leptin did not suppress the increased food intake in GPR17 -/- mice of the 129 strain, whereas it did suppress food intake in GPR17 +/+ mice. The only difference between GPR17 +/- and GPR17 +/+ mice of the C57Bl/6 strain was that the body weight of the GPR17 -/- mice was lower than that of the GPR17 +/+ mice when the mice were fed on a standard chow diet. We propose that the absence of GPR17 raises sympathetic activity in mice of the 129 strain in response to a low plasma fuel supply, and that the consequent loss of body fat is partly mitigated by increased energy intake.
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Affiliation(s)
- Edward T. Wargent
- Institute of Translational Medicine, University of Buckingham, Buckingham, United Kingdom
| | - Suhaib J. S. Ahmad
- Department of Surgery, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Qing Richard Lu
- Division of Experimental Hematology and Cancer Biology, Department of Pediatrics, Brain Tumor Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States
| | | | - Jonathan R. S. Arch
- Institute of Translational Medicine, University of Buckingham, Buckingham, United Kingdom
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Wargent ET, Kepczynska M, Zaibi MS, Hislop DC, Arch JRS, Stocker CJ. High fat-fed GPR55 null mice display impaired glucose tolerance without concomitant changes in energy balance or insulin sensitivity but are less responsive to the effects of the cannabinoids rimonabant or Δ(9)-tetrahydrocannabivarin on weight gain. PeerJ 2020; 8:e9811. [PMID: 32904155 PMCID: PMC7451014 DOI: 10.7717/peerj.9811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 08/04/2020] [Indexed: 12/14/2022] Open
Abstract
Background The insulin-sensitizing phytocannabinoid, Δ(9)-tetrahydrocannabivarin (THCV) can signal partly via G-protein coupled receptor-55 (GPR55 behaving as either an agonist or an antagonist depending on the assay). The cannabinoid receptor type 1 (CB1R) inverse agonist rimonabant is also a GPR55 agonist under some conditions. Previous studies have shown varied effects of deletion of GPR55 on energy balance and glucose homeostasis in mice. The contribution of signalling via GPR55 to the metabolic effects of THCV and rimonabant has been little studied. Methods In a preliminary experiment, energy balance and glucose homeostasis were studied in GPR55 knockout and wild-type mice fed on both standard chow (to 20 weeks of age) and high fat diets (from 6 to 15 weeks of age). In the main experiment, all mice were fed on the high fat diet (from 6 to 14 weeks of age). In addition to replicating the preliminary experiment, the effects of once daily administration of THCV (15 mg kg−1 po) and rimonabant (10 mg kg−1 po) were compared in the two genotypes. Results There was no effect of genotype on absolute body weight or weight gain, body composition measured by either dual-energy X-ray absorptiometry or Nuclear Magnetic Resonance (NMR), fat pad weights, food intake, energy expenditure, locomotor activity, glucose tolerance or insulin tolerance in mice fed on chow. When the mice were fed a high fat diet, there was again no effect of genotype on these various aspects of energy balance. However, in both experiments, glucose tolerance was worse in the knockout than the wild-type mice. Genotype did not affect insulin tolerance in either experiment. Weight loss in rimonabant- and THCV-treated mice was lower in knockout than in wild-type mice, but surprisingly there was no detectable effect of genotype on the effects of the drugs on any aspect of glucose homeostasis after taking into account the effect of genotype in vehicle-treated mice. Conclusions Our two experiments differ from those reported by others in finding impaired glucose tolerance in GPR55 knockout mice in the absence of any effect on body weight, body composition, locomotor activity or energy expenditure. Nor could we detect any effect of genotype on insulin tolerance, so the possibility that GPR55 regulates glucose-stimulated insulin secretion merits further investigation. By contrast with the genotype effect in untreated mice, we found that THCV and rimonabant reduced weight gain, and this effect was in part mediated by GPR55.
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Affiliation(s)
- Edward T Wargent
- Institute of Translational Medicine, University of Buckingham, Buckingham, United Kingdom
| | | | - Mohamed Sghaier Zaibi
- Institute of Translational Medicine, University of Buckingham, Buckingham, United Kingdom
| | - David C Hislop
- Medical School, University of Buckingham, Buckingham, United Kingdom
| | - Jonathan R S Arch
- Institute of Translational Medicine, University of Buckingham, Buckingham, United Kingdom
| | - Claire J Stocker
- Medical School, University of Buckingham, Buckingham, United Kingdom
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Merlin J, Sato M, Chia LY, Fahey R, Pakzad M, Nowell CJ, Summers RJ, Bengtsson T, Evans BA, Hutchinson DS. Rosiglitazone and a β 3-Adrenoceptor Agonist Are Both Required for Functional Browning of White Adipocytes in Culture. Front Endocrinol (Lausanne) 2018; 9:249. [PMID: 29910772 PMCID: PMC5992408 DOI: 10.3389/fendo.2018.00249] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/02/2018] [Indexed: 01/01/2023] Open
Abstract
The recruitment of brite (or beige) adipocytes has been advocated as a means to combat obesity, due to their ability to phenotypically resemble brown adipocytes (BA). Lineage studies indicate that brite adipocytes are formed by differentiation of precursor cells or by direct conversion of existing white adipocytes, depending on the adipose depot examined. We have systematically compared the gene expression profile and a functional output (oxygen consumption) in mouse adipocytes cultured from two contrasting depots, namely interscapular brown adipose tissue, and inguinal white adipose tissue (iWAT), following treatment with a known browning agent, the peroxisome proliferator-activated receptor (PPARγ) activator rosiglitazone. Prototypical BA readily express uncoupling protein (UCP)1, and upstream regulators including the β3-adrenoceptor and transcription factors involved in energy homeostasis. Adipocytes from inguinal WAT display maximal UCP1 expression and mitochondrial uncoupling only when treated with a combination of the PPARγ activator rosiglitazone and a β3-adrenoceptor agonist. In conclusion, brite adipocytes are fully activated only when a browning agent (rosiglitazone) and a thermogenic agent (β3-adrenoceptor agonist) are added in combination. The presence of rosiglitazone throughout the 7-day culture period partially masks the effects of β3-adrenoceptor signaling in inguinal white adipocyte cultures, whereas including rosiglitazone only for the first 3 days promotes robust β3-adrenoceptor expression and provides an improved window for detection of β3-adrenoceptor responses.
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Affiliation(s)
- Jon Merlin
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Masaaki Sato
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Ling Yeong Chia
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Richard Fahey
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Mohsen Pakzad
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Cameron J. Nowell
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Roger J. Summers
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Tore Bengtsson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Bronwyn A. Evans
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Dana S. Hutchinson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- Department of Pharmacology, Monash University, Clayton, VIC, Australia
- *Correspondence: Dana S. Hutchinson,
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Usta Atmaca H, Akbas F. THE EFFECT OF SHORT TERM ALPHA LIPOIC ACID ADMINISTRATION ON ADIPONECTIN AND BODY WEIGHT IN TYPE 2 DIABETES MELLITUS PATIENTS. ACTA ENDOCRINOLOGICA-BUCHAREST 2017; 13:461-466. [PMID: 31149217 DOI: 10.4183/aeb.2017.461] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Background Alpha lipoic acid (ALA) acts as essential co-factor for mitochondrion respiratory enzymes. It has an increasing importance in diabetic neuropathy treatment. Its positive effects on weight gain and metabolic parameters have also been discussed. In this study, we aimed to search for the effect of ALA on weight, appetite, adiponectin and metabolic parameters in type 2 diabetes mellitus patients. Methods This study is designed as a randomised, double-blind, placebo controlled, prospective study. 23 type 2 diabetes mellitus patients with peripheral neuropathy (6 normal weight, 17 obese) and 21 normal weight control group were included in the study. Patients were given 600mg/day oral ALA for 6 weeks, added to their routine therapy. Body mass index (BMI), adiponectin, fasting plasma glucose, HbA1C, lipid parameters and CRP levels were tested before and after ALA treatment. Results were evaluated using SPSS 15.0 for Windows. Results Adiponectin levels were statistically significantly lower and CRP levels were higher in diabetes group when compared to control group. Although ALA treatment caused a slight weight loss, it was not statistically significant. Appetite scores were decreased in the diabetes group but it did not cause statistically significant weight loss. There was no significant change in metabolic parameters or adiponectin after the treatment. Conclusions 600mg/dL ALA treatment for 6 weeks did not favor for metabolic parameters in type 2 diabetes patients. This result might be due to the dose or the duration of the treatment, genetic predisposition or dietery habits. Trial of higher doses for long terms might be needed for recovery.
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Affiliation(s)
- H Usta Atmaca
- Istanbul Training and Research Hospital, Dept. of Internal Medicine, Samatya, Istanbul, Turkey
| | - F Akbas
- Istanbul Training and Research Hospital, Dept. of Internal Medicine, Samatya, Istanbul, Turkey
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Aljamal JA, Badawneh M. Antilipolytic effects of 1,8-naphthyridine derivatives β-adrenoceptor antagonists in rat white adipocytes. Chem Biol Drug Des 2017; 90:119-127. [PMID: 28054456 DOI: 10.1111/cbdd.12933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/13/2016] [Accepted: 12/21/2016] [Indexed: 11/29/2022]
Abstract
The rat fat cell β-adrenoceptors were investigated by studying the effects of new 1,8-naphthyridine derivatives synthesized starting from 7-amino-2-chloro-3-phenyl-1,8-naphthyridine on lipolysis induced by isoprenaline, and alprenolol. Lipolysis induced by isoprenaline agonist was competitively antagonized by the 1,8-naphthyridine analogue with a 7-hydroxy-2-(4'-methoxybenzylamine)-6-nitro-3-phenyl substituent designated as 3. In contrast, 10, 50, and 100 μm of 7-methoxy and 7-ethoxy derivatives did not modify the concentration-response curve of isoprenaline. A rightward shift of the curve was, however, observed with 50 μm of a 7-methoxy-2-(4'-methoxybenzylamine)-6-amino-3-phenyl substituent designated as 10. The selective β1 -AR antagonist, 7-hydroxy-4-morpholinomethyl-2-piperazino-1,8-naphthyridine slightly reduced isoprenaline-induced lipolysis only at high doses. Alprenolol-mediated lipolytic effect was antagonized by derivative 3, 10 and the selective β3 -AR antagonist SR 59,230A, but resistant to the selective β1 -AR antagonist 7-hydroxy-4-morpholinomethyl-2-piperazino-1,8-naphthyridine. The results provide preliminary pharmacological evidence for the antilipolytic effect of the newly synthesized 1,8-naphthyridine derivatives on rat fat cells. The analogues designated as 3 and 10 were the most potent antagonists of this series.
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Ali ES, Hua J, Wilson CH, Tallis GA, Zhou FH, Rychkov GY, Barritt GJ. The glucagon-like peptide-1 analogue exendin-4 reverses impaired intracellular Ca(2+) signalling in steatotic hepatocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2135-46. [PMID: 27178543 DOI: 10.1016/j.bbamcr.2016.05.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/20/2016] [Accepted: 05/04/2016] [Indexed: 02/07/2023]
Abstract
The release of Ca(2+) from the endoplasmic reticulum (ER) and subsequent replenishment of ER Ca(2+) by Ca(2+) entry through store-operated Ca(2+) channels (SOCE) play critical roles in the regulation of liver metabolism by adrenaline, glucagon and other hormones. Both ER Ca(2+) release and Ca(2+) entry are severely inhibited in steatotic hepatocytes. Exendin-4, a slowly-metabolised glucagon-like peptide-1 (GLP-1) analogue, is known to reduce liver glucose output and liver lipid, but the mechanisms involved are not well understood. The aim of this study was to determine whether exendin-4 alters intracellular Ca(2+) homeostasis in steatotic hepatocytes, and to evaluate the mechanisms involved. Exendin-4 completely reversed lipid-induced inhibition of SOCE in steatotic liver cells, but did not reverse lipid-induced inhibition of ER Ca(2+) release. The action of exendin-4 on Ca(2+) entry was rapid in onset and was mimicked by GLP-1 or dibutyryl cyclic AMP. In steatotic liver cells, exendin-4 caused a rapid decrease in lipid (half time 6.5min), inhibited the accumulation of lipid in liver cells incubated in the presence of palmitate plus the SOCE inhibitor BTP-2, and enhanced the formation of cyclic AMP. Hormone-stimulated accumulation of extracellular glucose in glycogen replete steatotic liver cells was inhibited compared to that in non-steatotic cells, and this effect of lipid was reversed by exendin-4. It is concluded that, in steatotic hepatocytes, exendin-4 reverses the lipid-induced inhibition of SOCE leading to restoration of hormone-regulated cytoplasmic Ca(2+) signalling. The mechanism may involve GLP-1 receptors, cyclic AMP, lipolysis, decreased diacylglycerol and decreased activity of protein kinase C.
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Affiliation(s)
- Eunüs S Ali
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia
| | - Jin Hua
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia
| | - Claire H Wilson
- Molecular Regulation Laboratory, Centre for Cancer Biology, Division of Health Sciences, University of South Australia, Adelaide, South Australia, 5001, Australia
| | - George A Tallis
- Medical Biochemistry, SA Pathology, Finders Medical Centre, Bedford Park, South Australia 5042, Australia
| | - Fiona H Zhou
- School of Medicine, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, South Australia 5005, Australia
| | - Grigori Y Rychkov
- School of Medicine, The University of Adelaide, and South Australian Health and Medical Research Institute, Adelaide, South Australia 5005, Australia
| | - Greg J Barritt
- Department of Medical Biochemistry and Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, South Australia 5001, Australia.
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Arch JRS, Trayhurn P. Detection of thermogenesis in rodents in response to anti-obesity drugs and genetic modification. Front Physiol 2013; 4:64. [PMID: 23580228 PMCID: PMC3619105 DOI: 10.3389/fphys.2013.00064] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/16/2013] [Indexed: 11/22/2022] Open
Abstract
Many compounds and genetic manipulations are claimed to confer resistance to obesity in rodents by raising energy expenditure. Examples taken from recent and older literature, demonstrate that such claims are often based on measurements of energy expenditure after body composition has changed, and depend on comparisons of energy expenditure divided by body weight. This is misleading because white adipose tissue has less influence than lean tissue on energy expenditure. Application of this approach to human data would suggest that human obesity is usually due to a low metabolic rate, which is not an accepted view. Increased energy expenditure per animal is a surer way of demonstrating thermogenesis, but even then it is important to know whether this is due to altered body composition (repartitioning), or increased locomotor activity rather than thermogenesis per se. Regression analysis offers other approaches. The thermogenic response to some compounds has a rapid onset and so cannot be due to altered body composition. These compounds usually mimic or activate the sympathetic nervous system. Thermogenesis occurs in, but may not be confined to, brown adipose tissue. It should not be assumed that weight loss in response to these treatments is due to thermogenesis unless there is a sustained increase in 24-h energy expenditure. Thyroid hormones and fibroblast growth factor 21 also raise energy expenditure before they affect body composition. Some treatments and genetic modifications alter the diurnal rhythm of energy expenditure. It is important to establish whether this is due to altered locomotor activity or efficiency of locomotion. There are no good examples of compounds that do not affect short-term energy expenditure but have a delayed effect. How and under what conditions a genetic modification or compound increases energy expenditure influences the decision on whether to seek drugs for the target or take a candidate drug into clinical studies.
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Dulloo AG, Jacquet J, Montani JP, Schutz Y. Adaptive thermogenesis in human body weight regulation: more of a concept than a measurable entity? Obes Rev 2012; 13 Suppl 2:105-21. [PMID: 23107264 DOI: 10.1111/j.1467-789x.2012.01041.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
According to Lavoisier, 'Life is combustion'. But to what extent humans adapt to changes in food intake through adaptive thermogenesis--by turning down the rate of heat production during energy deficit (so as to conserve energy) or turning it up during overnutrition (so as to dissipate excess calories)--has been one of the most controversial issues in nutritional sciences over the past 100 years. The debate nowadays is not whether adaptive thermogenesis exists or not, but rather about its quantitative importance in weight homoeostasis and its clinical relevance to the pathogenesis and management of obesity. Such uncertainties are likely to persist in the foreseeable future primarily because of limitations to unobtrusively measure changes in energy expenditure and body composition with high enough accuracy and precision, particularly when even small inter-individual variations in thermogenesis can, in dynamic systems and over the long term, be important in the determining weight maintenance in some and obesity and weight regain in others. This paper reviews the considerable body of evidence, albeit fragmentary, suggesting the existence of quantitatively important adaptive thermogenesis in several compartments of energy expenditure in response to altered food intake. It then discusses the various limitations that lead to over- or underestimations in its assessment, including definitional and semantics, technical and methodological, analytical and statistical. While the role of adaptive thermogenesis in human weight regulation is likely to remain more a concept than a strictly 'quantifiable' entity in the foreseeable future, the evolution of this concept continues to fuel exciting hypothesis-driven mechanistic research which contributes to advance knowledge in human metabolism and which is bound to result in improved strategies for the management of a healthy body weight.
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Affiliation(s)
- A G Dulloo
- Department of Medicine/Physiology, University of Fribourg, Chemin du musée 5, Fribourg, Switzerland.
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Affiliation(s)
- Jonathan R. S. Arch
- Clore Laboratory, University of Buckingham, Hunter Street, Buckingham MK18 1EG, UK
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