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Zhang H, Yan X, Lin A, Xia P, Su Y. Inhibition of ghrelin activity by the receptor antagonist [D-Lys3]-GHRP-6 enhances hepatic fatty acid oxidation and gluconeogenesis in a growing pig model. Peptides 2023; 166:171041. [PMID: 37301480 DOI: 10.1016/j.peptides.2023.171041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/05/2023] [Accepted: 06/07/2023] [Indexed: 06/12/2023]
Abstract
Despite its central role in regulating energy intake and metabolism, ghrelin is little understood when it comes to its effects on hepatic lipid and glucose metabolism. Growing pigs were intravenously injected with ghrelin receptor antagonist [D-Lys3]-GHRP-6 (DLys; 6 mg/kg body weight) for seven days to determine whether ghrelin plays a role in glucose and lipid metabolism. DLys treatment significantly reduced body weight gain and adipose histopathology found that DLys treatment dramatically reduced adipocyte size. DLys treatment significantly increased serum NEFA and insulin levels, hepatic glucose level and HOMA-IR, and significantly decreased serum TBA level of growing pigs after fasting. Moreover, DLys treatment changed the dynamics of serum metabolic parameters, including glucose, NEFA, TBA, insulin, GH, leptin, and cortisol. Liver transcriptome showed that DLys treatment affected the metabolism-related pathways. Compared with the control group, adipose tissue lipolysis (the adipose triglyceride lipase level was significantly increased), hepatic gluconeogenesis (the G6PC protein level was significantly increased) and fatty acid oxidation (the CPT1A protein level was significantly increased) were promoted in the DLys group. DLys treatment expanded degrees of oxidative phosphorylation in the liver, coming about in a higher NAD+ /NADH proportion and enactment of the SIRT1 signaling pathway. Additionally, the liver protein levels of the DLys group were significantly higher than those of the control group for GHSR, PPAR alpha, and PGC-1. To summarize, inhibition of ghrelin activity can significantly affect metabolism and alter energy levels by enhancing fat mobilization, hepatic fatty acid oxidation and gluconeogenesis without affecting fatty acid uptake and synthesis in the liver.
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Affiliation(s)
- He Zhang
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, 210095 Nanjing, China; National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, 210095 Nanjing, China; College of Life Sciences, Xuzhou Medical University, 221004 Xuzhou, China
| | - Xiaoxi Yan
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, 210095 Nanjing, China; National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, 210095 Nanjing, China
| | - Ailian Lin
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, 210095 Nanjing, China; National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, 210095 Nanjing, China
| | - Pengke Xia
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, 210095 Nanjing, China; National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, 210095 Nanjing, China
| | - Yong Su
- Laboratory of Gastrointestinal Microbiology, Jiangsu Key Laboratory of Gastrointestinal Nutrition and Animal Health, College of Animal Science and Technology, Nanjing Agricultural University, 210095 Nanjing, China; National Center for International Research on Animal Gut Nutrition, Nanjing Agricultural University, 210095 Nanjing, China.
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2
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Karnošová A, Strnadová V, Železná B, Kuneš J, Kašpárek P, Maletínská L. NPFFR2-deficient mice fed a high-fat diet develop strong intolerance to glucose. Clin Sci (Lond) 2023; 137:847-862. [PMID: 37191311 PMCID: PMC10240834 DOI: 10.1042/cs20220880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 05/17/2023]
Abstract
A previous study on neuropeptide FF receptor 2 (NPFFR2)-deficient mice has demonstrated that NPFFR2 is involved in the control of energy balance and thermogenesis. Here, we report on the metabolic impact of NPFFR2 deficiency in male and female mice that were fed either a standard diet (STD) or a high-fat diet (HFD) and each experimental group consisted of ten individuals. Both male and female NPFFR2 knockout (KO) mice exhibited severe glucose intolerance that was exacerbated by a HFD diet. In addition, reduced insulin pathway signaling proteins in NPFFR2 KO mice fed a HFD resulted in the development of hypothalamic insulin resistance. HFD feeding did not cause liver steatosis in NPFFR2 KO mice of either sex, but NPFFR2 KO male mice fed a HFD had lower body weights, white adipose tissues, and liver and lower plasma leptin levels compared with their wild-type (WT) controls. Lower liver weight in NPFFR2 KO male mice compensated for HFD-induced metabolic stress by increased liver PPARα and plasma FGF21 hepatokine, which supported fatty acid β-oxidation in the liver and white adipose tissue. Conversely, NPFFR2 deletion in female mice attenuated the expression of Adra3β and Pparγ, which inhibited lipolysis in adipose tissue.
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Affiliation(s)
- Alena Karnošová
- Biochemistry and molecular biology, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
- First Faculty of Medicine, Charles University, 12108 Prague, Czech Republic
| | - Veronika Strnadová
- Biochemistry and molecular biology, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Blanka Železná
- Biochemistry and molecular biology, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Jaroslav Kuneš
- Biochemistry and molecular biology, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
- Experimental hypertension, Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Petr Kašpárek
- Czech Centre for Phenogenomics, Institute of Molecular Genetics of the Czech Academy of Sciences, Vestec 25250, Czech Republic
| | - Lenka Maletínská
- Biochemistry and molecular biology, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
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3
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Regulation of feeding and therapeutic application of bioactive peptides. Pharmacol Ther 2022; 239:108187. [DOI: 10.1016/j.pharmthera.2022.108187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/25/2022] [Accepted: 04/07/2022] [Indexed: 10/18/2022]
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Alharbi S. Exogenous administration of unacylated ghrelin attenuates hepatic steatosis in high-fat diet-fed rats by modulating glucose homeostasis, lipogenesis, oxidative stress, and endoplasmic reticulum stress. Biomed Pharmacother 2022; 151:113095. [PMID: 35594708 DOI: 10.1016/j.biopha.2022.113095] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 05/01/2022] [Accepted: 05/04/2022] [Indexed: 11/25/2022] Open
Abstract
Low levels of unacylated ghrelin (UAG) and a higher ratio of acylated ghrelin (AG)/UAG in obesity are associated with non-alcoholic fatty liver disease (NAFLD). This study tested the potential protective effect of increased circulatory levels of UAG by exogenous UAG administration on hepatic steatosis in high-fat diet (HFD)-fed rats and investigated some possible mechanisms. Rats were divided (n = 6/group) as low fat diet (LFD), LFD + UAG (200 mg/kg), HFD, HFD + UAG (50, 100, or 200 mg/kg). Treatments were given for 8 weeks. Increasing the dose of UAG increased circulatory levels of UAG and normalized the ratio of AG/UAG at the dose of 200 mg/kg. With no change in insulin levels, and in a dose-dependent manner, treatment with UAG to HFD rats attenuated the gain in food intake, body weights, and liver weights, lowered fasting glucose levels, prevented hepatic cytoplasmic vacuolization, and reduced serum and hepatic levels of cholesterol, triglycerides, and free fatty acids. They also progressively reduced levels of reactive oxygen species, lipid peroxides, tumor necrosis factor-α, and interleukin-6, as well as mRNA levels of Bax and caspase-3 but increased levels of glutathione and superoxide dismutase and mRNA levels of Bcl2. In concomitant, UAG, in a dose-response manner, significantly reduced hepatic mRNA levels of SREBP1, SREBP2, ATF-6, IRE-1, and eIF-2α but increased those of PPARα. In conclusion, reducing the circulatory ratio of AG/UAG ratio by exogenous administration of UAG attenuates HFD-induced hepatic steatosis by suppressing lipogenesis, stimulating FAs oxidation, preventing oxidative stress, inflammation, ER stress, and apoptosis.
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Affiliation(s)
- Samah Alharbi
- Physiology Department, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia.
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5
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Kaiser J, Krippeit-Drews P, Drews G. Acyl-Ghrelin Influences Pancreatic β-Cell Function by Interference with K ATP Channels. Diabetes 2021; 70:423-435. [PMID: 33154069 DOI: 10.2337/db20-0231] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 11/03/2020] [Indexed: 11/13/2022]
Abstract
The aim for this study was to elucidate how the hypothalamic hunger-inducing hormone acyl-ghrelin (AG), which is also produced in the pancreas, affects β-cell function, with particular attention to the role of ATP-sensitive K+ (KATP) channels and the exact site of action of the hormone. AG hyperpolarized the membrane potential and decreased cytoplasmic calcium concentration [Ca2+]c and glucose-stimulated insulin secretion (GSIS). These effects were abolished in β-cells from SUR1-knockout (KO) mice. AG increased KATP current but only in a configuration with intact metabolism. Unacylated ghrelin counteracted the effects of AG. The influence of AG on membrane potential and GSIS could only be averted in the combined presence of a ghrelin receptor (GHSR1a) antagonist and an inverse agonist. The inhibition of GSIS by AG could be prevented by dibutyryl cyclic-cAMP or 3-isobutyl-1-methylxanthine and the somatostatin (SST) receptor 2-5 antagonist H6056. These data indicate that AG indirectly opens KATP channels probably by interference with the cAMP/cAMP-dependent protein kinase pathway, resulting in a decrease of [Ca2+]c and GSIS. The experiments with SUR1-KO β-cells point to a direct effect of AG on β-cells and not, as earlier suggested, to an exclusive effect by AG-induced SST release from δ-cells. Nevertheless, SST receptors may be involved in the effect of AG, possibly by heteromerization of AG and SST receptors.
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Affiliation(s)
- Julia Kaiser
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Peter Krippeit-Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Gisela Drews
- Department of Pharmacology, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
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Pražienková V, Funda J, Pirník Z, Karnošová A, Hrubá L, Kořínková L, Neprašová B, Janovská P, Benzce M, Kadlecová M, Blahoš J, Kopecký J, Železná B, Kuneš J, Bardová K, Maletínská L. GPR10 gene deletion in mice increases basal neuronal activity, disturbs insulin sensitivity and alters lipid homeostasis. Gene 2021; 774:145427. [PMID: 33450349 DOI: 10.1016/j.gene.2021.145427] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/27/2020] [Accepted: 01/05/2021] [Indexed: 02/07/2023]
Abstract
G-protein-coupled receptor GPR10 is expressed in brain areas regulating energy metabolism. In this study, the effects of GPR10 gene deficiency on energy homeostasis in mice of both sexes fed either standard chow or a high-fat diet (HFD) were studied, with a focus on neuronal activation of PrRP neurons, and adipose tissue and liver metabolism. GPR10 deficiency in males upregulated the phasic and tonic activity of PrRP neurons in the nucleus of the solitary tract. GPR10 knockout (KO) males on a standard diet displayed a higher body weight than their wild-type (WT) littermates due to an increase in adipose tissue mass; however, HFD feeding did not cause weight differences between genotypes. Expression of lipogenesis genes was suppressed in the subcutaneous adipose tissue of GPR10 KO males. In contrast, GPR10 KO females did not differ in body weight from their WT controls, but showed elevated expression of lipid metabolism genes in the liver and subcutaneous adipose tissue compared to WT controls. An attenuated non-esterified fatty acids change after glucose load compared to WT controls suggested a defect in insulin-mediated suppression of lipolysis in GPR10 KO females. Indirect calorimetry did not reveal any differences in energy expenditure among groups. In conclusion, deletion of GPR10 gene resulted in changes in lipid metabolism in mice of both sexes, however in different extent. An increase in adipose tissue mass observed in only GPR10 KO males may have been prevented in GPR10 KO females owing to a compensatory increase in the expression of metabolic genes.
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Affiliation(s)
- Veronika Pražienková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Jiří Funda
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Zdenko Pirník
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic; Biomedical Research Center SAS of the Slovak Academy of Sciences, 845 05 Bratislava, Slovak Republic; Institute of Physiology, Faculty of Medicine, Comenius University in Bratislava, 813 72 Bratislava, Slovak Republic
| | - Alena Karnošová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Lucie Hrubá
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Lucia Kořínková
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Barbora Neprašová
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Petra Janovská
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Michal Benzce
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Michaela Kadlecová
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Jaroslav Blahoš
- Institute of Molecular Genetics of the Czech Academy of Sciences, 14220 Prague, Czech Republic
| | - Jan Kopecký
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Blanka Železná
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic
| | - Jaroslav Kuneš
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic; Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Kristina Bardová
- Institute of Physiology of the Czech Academy of Sciences, 14200 Prague, Czech Republic
| | - Lenka Maletínská
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, 16610 Prague, Czech Republic.
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7
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Estradiol Replacement Improves High-Fat Diet-Induced Obesity by Suppressing the Action of Ghrelin in Ovariectomized Rats. Nutrients 2020; 12:nu12040907. [PMID: 32224927 PMCID: PMC7230822 DOI: 10.3390/nu12040907] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 03/17/2020] [Accepted: 03/24/2020] [Indexed: 12/16/2022] Open
Abstract
This study aims to investigate the effects of estradiol replacement on the orexigenic action of ghrelin in ovariectomized (OVX) obese rats fed with a high-fat diet (HFD). Four weeks after OVX at 9 weeks of age, Wistar rats were subcutaneously implanted with either 17β-estradiol (E2) or placebo (Pla) pellets and started on HFD feeding. After 4 weeks, growth hormone-releasing peptide (GHRP)-6, a growth hormone secretagogue receptor (GHSR) agonist injected intraperitoneally, induced changes in HFD intake, and c-Fos-positive neurons in the hypothalamic arcuate nucleus (ARC) were measured in both groups. The ghrelin protein and mRNA levels, as well as GHSR protein in stomach, were analyzed by Western blotting and real-time PCR. HFD increased energy intake and body weight in the Pla group, while it temporarily reduced these in the E2 group. GHRP-6 enhanced HFD intake and activated neurons in the ARC only in the Pla group. Furthermore, gastric ghrelin and GHSR protein levels were lower in the E2 group than in the Pla group, but plasma acyl ghrelin levels were similar in both groups. Our results suggest that E2 replacement improves obesity by inhibiting the orexigenic action of ghrelin via downregulation of ghrelin and its receptor in stomach in HFD-fed OVX rats.
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Rasineni K, Kubik JL, Casey CA, Kharbanda KK. Inhibition of Ghrelin Activity by Receptor Antagonist [d-Lys-3] GHRP-6 Attenuates Alcohol-Induced Hepatic Steatosis by Regulating Hepatic Lipid Metabolism. Biomolecules 2019; 9:biom9100517. [PMID: 31546643 PMCID: PMC6843513 DOI: 10.3390/biom9100517] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 01/13/2023] Open
Abstract
Alcoholic steatosis, characterized by an accumulation of triglycerides in hepatocytes, is one of the earliest pathological changes in the progression of alcoholic liver disease. In our previous study, we showed that alcohol-induced increase in serum ghrelin levels impair insulin secretion from pancreatic β-cells. The consequent reduction in the circulating insulin levels promote adipose-derived fatty acid mobilization to ultimately contribute to hepatic steatosis. In this study, we determined whether inhibition of ghrelin activity in chronic alcohol-fed rats could improve hepatic lipid homeostasis at the pancreas-adipose-liver axis. Adult Wistar rats were fed Lieber-DeCarli control or an ethanol liquid diet for 7 weeks. At 6 weeks, a subset of rats in each group were injected with either saline or ghrelin receptor antagonist, [d-Lys-3] GHRP-6 (DLys; 9 mg/kg body weight) for 5 days and all rats were sacrificed 2 days later. DLys treatment of ethanol rats improved pancreatic insulin secretion, normalized serum insulin levels, and the adipose lipid metabolism, as evidenced by the decreased serum free fatty acids (FFA). DLys treatment of ethanol rats also significantly decreased the circulating FFA uptake, de novo hepatic fatty acid synthesis ultimately attenuating alcoholic steatosis. To summarize, inhibition of ghrelin activity reduced alcoholic steatosis by improving insulin secretion, normalizing serum insulin levels, inhibiting adipose lipolysis, and preventing fatty acid uptake and synthesis in the liver. Our studies provided new insights on the important role of ghrelin in modulating the pancreas-adipose-liver, and promoting adipocyte lipolysis and hepatic steatosis. The findings offer a therapeutic approach of not only preventing alcoholic liver injury but also treating it.
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Affiliation(s)
- Karuna Rasineni
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Jacy L Kubik
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Carol A Casey
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Kusum K Kharbanda
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
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Mosa R, Huang L, Li H, Grist M, LeRoith D, Chen C. Long-term treatment with the ghrelin receptor antagonist [d-Lys3]-GHRP-6 does not improve glucose homeostasis in nonobese diabetic MKR mice. Am J Physiol Regul Integr Comp Physiol 2017; 314:R71-R83. [PMID: 28903914 DOI: 10.1152/ajpregu.00157.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Long-term treatment with the ghrelin receptor antagonist [d-Lys3]-GHRP-6 does not improve glucose homeostasis in nonobese diabetic MKR mice. Am J Physiol Regul Integr Comp Physiol 314: R71-R83, 2018. First published September 13, 2017; doi: 10.1152/ajpregu.00157.2017 .-Ghrelin secretion has been associated with increased caloric intake and adiposity. The expressions of ghrelin and its receptor (GHS-R1a) in the pancreas has raised the interest about the role of ghrelin in glucose homeostasis. Most of the studies showed that ghrelin promoted hyperglycemia and inhibited insulin secretion. This raised the interest in using GHS-R1a antagonists as therapeutic targets for type 2 diabetes. Available data of GHS-R antagonists are on a short-term basis. Moreover, the complexity of GHS-R1a signaling makes it difficult to understand the mechanism of action of GHS-R1a antagonists. This study examined the possible effects of long-term treatment with a GHS-R1a antagonist, [d-Lys3]-growth hormone-releasing peptide (GHRP)-6, on glucose homeostasis, food intake, and indirect calorimetric parameters in nonobese diabetic MKR mice. Our results showed that [d-Lys3]-GHRP-6 (200 nmol/mouse) reduced pulsatile growth hormone secretion and body fat mass as expected but worsened glucose and insulin intolerances and increased cumulative food intake unexpectedly. In addition, a significant increase in blood glucose and decreases in plasma insulin and C-peptide levels were observed in MKR mice following long-term [d-Lys3]-GHRP-6 treatment, suggesting a direct inhibition of insulin secretion. Immunofluorescence staining of pancreatic islets showed a proportional increase in somatostatin-positive cells and a decrease in insulin-positive cells in [d-Lys3]-GHRP-6-treated mice. Furthermore, [d-Lys3]-GHRP-6 stimulated food intake on long-term treatment via reduction of proopiomelanocortin gene expression and antagonized GH secretion via reduced growth hormone-releasing hormone gene expression in hypothalamus. These results demonstrate that [d-Lys3]-GHRP-6 is not completely opposite to ghrelin and may not be a treatment option for type 2 diabetes.
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Affiliation(s)
- Rasha Mosa
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Lili Huang
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Hongzhuo Li
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Michael Grist
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
| | - Derek LeRoith
- Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland
| | - Chen Chen
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, Australia
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Azegami T, Yuki Y, Sawada S, Mejima M, Ishige K, Akiyoshi K, Itoh H, Kiyono H. Nanogel-based nasal ghrelin vaccine prevents obesity. Mucosal Immunol 2017; 10:1351-1360. [PMID: 28120848 DOI: 10.1038/mi.2016.137] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 12/19/2016] [Indexed: 02/04/2023]
Abstract
Obesity is associated with multiple comorbidities such as cardiovascular diseases and has a huge economic impact on the health-care system. However, the treatment of obesity remains insufficient in terms of efficacy, tolerability, and safety. Here we created a nasal vaccine against obesity for the first time. To avoid the injectable administration-caused pain and skin-related adverse event, we focused on the intranasal route of antigen delivery. We developed a vaccine antigen (ghrelin-PspA (pneumococcal surface protein A)), which is a recombinant fusion protein incorporating ghrelin, a hormone that stimulates food intake and decreases energy expenditure, and PspA, a candidate of pneumococcal vaccine as a carrier protein. Ghrelin-PspA antigen was mixed with cyclic di-GMP adjuvant to enhance the immunogenicity and incorporated within a nanometer-sized hydrogel for the effective antigen delivery. Intranasal immunization with ghrelin-PspA vaccine elicited serum immunoglobulin G antibodies against ghrelin and attenuated body weight gain in diet-induced obesity mice. This obesity-attenuating effect was caused by a decrease in fat accumulation and an increase in energy expenditure that was partially due to an increase in the expression of mitochondrial uncoupling protein 1 in brown adipose tissue. The development of this nasal vaccine provides a new strategy for the prevention and treatment of obesity.
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Affiliation(s)
- T Azegami
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.,Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Y Yuki
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - S Sawada
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.,Japan Science and Technology Agency (JST), The Exploratory Research for Advanced Technology (ERATO), Katura Int' Tech Center, Kyoto, Japan
| | - M Mejima
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - K Ishige
- Biochemicals Division, Yamasa Corporation, Chiba, Japan
| | - K Akiyoshi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.,Japan Science and Technology Agency (JST), The Exploratory Research for Advanced Technology (ERATO), Katura Int' Tech Center, Kyoto, Japan
| | - H Itoh
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan
| | - H Kiyono
- Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.,International Research and Development Center for Mucosal Vaccines, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
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11
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Colldén G, Tschöp MH, Müller TD. Therapeutic Potential of Targeting the Ghrelin Pathway. Int J Mol Sci 2017; 18:ijms18040798. [PMID: 28398233 PMCID: PMC5412382 DOI: 10.3390/ijms18040798] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/03/2017] [Accepted: 04/06/2017] [Indexed: 02/07/2023] Open
Abstract
Ghrelin was discovered in 1999 as the endogenous ligand of the growth-hormone secretagogue receptor 1a (GHSR1a). Since then, ghrelin has been found to exert a plethora of physiological effects that go far beyond its initial characterization as a growth hormone (GH) secretagogue. Among the numerous well-established effects of ghrelin are the stimulation of appetite and lipid accumulation, the modulation of immunity and inflammation, the stimulation of gastric motility, the improvement of cardiac performance, the modulation of stress, anxiety, taste sensation and reward-seeking behavior, as well as the regulation of glucose metabolism and thermogenesis. Due to a variety of beneficial effects on systems’ metabolism, pharmacological targeting of the endogenous ghrelin system is widely considered a valuable approach to treat metabolic complications, such as chronic inflammation, gastroparesis or cancer-associated anorexia and cachexia. The aim of this review is to discuss and highlight the broad pharmacological potential of ghrelin pathway modulation for the treatment of anorexia, cachexia, sarcopenia, cardiopathy, neurodegenerative disorders, renal and pulmonary disease, gastrointestinal (GI) disorders, inflammatory disorders and metabolic syndrome.
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Affiliation(s)
- Gustav Colldén
- Institute for Diabetes and Obesity & Helmholtz Diabetes Center, Helmholtz Zentrum München German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany.
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity & Helmholtz Diabetes Center, Helmholtz Zentrum München German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany.
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, 80333 Munich, Germany.
| | - Timo D Müller
- Institute for Diabetes and Obesity & Helmholtz Diabetes Center, Helmholtz Zentrum München German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany.
- Institute for Diabetes and Obesity (IDO), Business Campus Garching-Hochbrück, Parkring 13, 85748 Garching, Germany.
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12
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Churm R, Davies JS, Stephens JW, Prior SL. Ghrelin function in human obesity and type 2 diabetes: a concise review. Obes Rev 2017; 18:140-148. [PMID: 27899023 DOI: 10.1111/obr.12474] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/06/2016] [Accepted: 09/06/2016] [Indexed: 12/12/2022]
Abstract
The 28 amino acid hormone, ghrelin, has been found to have various effects on metabolism. This review will focus on the pathways integrated into ghrelin's effect within the hypothalamus, pancreas and adipocytes. The identification of molecules and pathways that regulate ghrelin-mediated lipid retention could establish new mechanisms underlying cellular energy homeostasis. The impact of acyl-ghrelin on glucose metabolism and lipid homeostasis may allow for novel preventative or early intervention therapeutic strategies to treat obesity related type 2 diabetes and associated metabolic dysfunction.
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Affiliation(s)
- R Churm
- Diabetes Research Group, Institute of Life Science 1, Swansea University, Swansea, UK
| | - J S Davies
- Molecular Neurobiology Research Group, Institute of Life Science 1, Swansea University, Swansea, UK
| | - J W Stephens
- Diabetes Research Group, Institute of Life Science 1, Swansea University, Swansea, UK
| | - S L Prior
- Diabetes Research Group, Institute of Life Science 1, Swansea University, Swansea, UK
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13
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Ghrelin-Induced Enhancement of Vasopressin and Oxytocin Secretion in Rat Neurohypophyseal Cell Cultures. J Mol Neurosci 2016; 60:525-530. [DOI: 10.1007/s12031-016-0850-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/06/2016] [Indexed: 11/26/2022]
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14
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Pelantová H, Bugáňová M, Holubová M, Šedivá B, Zemenová J, Sýkora D, Kaválková P, Haluzík M, Železná B, Maletínská L, Kuneš J, Kuzma M. Urinary metabolomic profiling in mice with diet-induced obesity and type 2 diabetes mellitus after treatment with metformin, vildagliptin and their combination. Mol Cell Endocrinol 2016; 431:88-100. [PMID: 27164444 DOI: 10.1016/j.mce.2016.05.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 04/15/2016] [Accepted: 05/05/2016] [Indexed: 01/06/2023]
Abstract
Metformin, vildagliptin and their combination are widely used for the treatment of diabetes, but little is known about the metabolic responses to these treatments. In the present study, NMR-based metabolomics was applied to detect changes in the urinary metabolomic profile of a mouse model of diet-induced obesity in response to these treatments. Additionally, standard biochemical parameters and the expression of enzymes involved in glucose and fat metabolism were monitored. Significant correlations were observed between several metabolites (e.g., N-carbamoyl-β-alanine, N1-methyl-4-pyridone-3-carboxamide, N1-methyl-2-pyridone-5-carboxamide, glucose, 3-indoxyl sulfate, dimethylglycine and several acylglycines) and the area under the curve of glucose concentrations during the oral glucose tolerance test. The present study is the first to present N-carbamoyl-β-alanine as a potential marker of type 2 diabetes mellitus and consequently to demonstrate the efficacies of the applied antidiabetic interventions. Moreover, the elevated acetate level observed after vildagliptin administration might reflect increased fatty acid oxidation.
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Affiliation(s)
- Helena Pelantová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic; Department of Analytical Chemistry, Faculty of Science, Palacký University, 17 listopadu 1192/12, 771 46, Olomouc, Czech Republic
| | - Martina Bugáňová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic; Faculty of Chemical Technology, University of Chemistry and Technology Prague, Technická 5, 166 28, Prague 6, Czech Republic
| | - Martina Holubová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Blanka Šedivá
- Faculty of Applied Sciences, University of West Bohemia, Univerzitní 8, 306 14, Plzeň, Czech Republic
| | - Jana Zemenová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic; Faculty of Chemical Engineering, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - David Sýkora
- Faculty of Chemical Engineering, University of Chemistry and Technology Prague, Technická 3, 166 28, Prague 6, Czech Republic
| | - Petra Kaválková
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General Faculty Hospital in Prague, U nemocnice 1, 128 08, Prague 2, Czech Republic
| | - Martin Haluzík
- Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University and General Faculty Hospital in Prague, U nemocnice 1, 128 08, Prague 2, Czech Republic; Institute of Endocrinology, Národní 8, 116 94, Prague 1, Czech Republic
| | - Blanka Železná
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Lenka Maletínská
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic
| | - Jaroslav Kuneš
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10, Prague 6, Czech Republic; Institute of Physiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Marek Kuzma
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20, Prague 4, Czech Republic.
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15
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Holubová M, Zemenová J, Mikulášková B, Panajotova V, Stöhr J, Haluzík M, Kuneš J, Železná B, Maletínská L. Palmitoylated PrRP analog decreases body weight in DIO rats but not in ZDF rats. J Endocrinol 2016; 229:85-96. [PMID: 26906745 DOI: 10.1530/joe-15-0519] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/23/2016] [Indexed: 12/30/2022]
Abstract
Anorexigenic neuropeptides produced and acting in the brain have the potential to decrease food intake and ameliorate obesity, but are ineffective after peripheral application, owing to a limited ability to cross the blood-brain barrier. We have designed lipidized analogs of prolactin-releasing peptide (PrRP), which is involved in energy balance regulation as demonstrated by obesity phenotypes of both Prrp-knockout and Prrp receptor-knockout mice. The aim of this study was to characterize the subchronic effect of a palmitoylated PrRP analog in two rat models of obesity and diabetes: diet-induced obese Sprague-Dawley rats and leptin receptor-deficient Zucker diabetic (ZDF) rats. In the rats with diet-induced obesity (DIO), a two-week intraperitoneal treatment with palmitoylated PrRP lowered food intake by 24% and body weight by 8%. This treatment also improved glucose tolerance and tended to decrease leptin levels and adipose tissue masses in a dose-dependent manner. In contrast, in ZDF rats, the same treatment with palmitoylated PrRP lowered food intake but did not significantly affect body weight or glucose tolerance, probably in consequence of severe leptin resistance due to a nonfunctional leptin receptor. Our data indicate a good efficacy of lipidized PrRP in DIO rats. Thus, the strong anorexigenic, body weight-reducing, and glucose tolerance-improving effects make palmitoylated PrRP an attractive candidate for anti-obesity treatment.
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Affiliation(s)
- Martina Holubová
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jana Zemenová
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic Department of Analytical ChemistryUniversity of Chemistry and Technology, Prague, Czech Republic
| | - Barbora Mikulášková
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic Institute of PhysiologyAcademy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | | | - Martin Haluzík
- First Faculty of MedicineCharles University, Prague, Czech Republic
| | - Jaroslav Kuneš
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic Institute of PhysiologyAcademy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Blanka Železná
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Lenka Maletínská
- Institute of Organic Chemistry and BiochemistryAcademy of Sciences of the Czech Republic, Prague, Czech Republic
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16
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Ferro P, Krotov G, Zvereva I, Rodchenkov G, Segura J. Structure-activity relationship for peptídic growth hormone secretagogues. Drug Test Anal 2016; 9:87-95. [PMID: 26811125 DOI: 10.1002/dta.1947] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/05/2015] [Accepted: 12/10/2015] [Indexed: 11/11/2022]
Abstract
Growth hormone releasing peptides (GHRPs) could be widely used by cheating athletes because they produce growth hormone (GH) secretion, so may generate an ergogenic effect in the body. Knowledge of the essential amino acids needed in GHRP structure for interaction with the target biological receptor GHSR1a, the absorption through different administration routes, and the maintenance of pharmacological activity of potential biotransformation products may help in the fight against their abuse in sport. Several GHRPs and truncated analogues with the common core Ala-Trp-(D-Phe)-Lys have been studied with a radio-competitive assay for the GHSR1a receptor against the radioactive natural ligand ghrelin. Relevant chemical modifications influencing the activity for positions 1, 2, 3, and 7 based on the structure aa-aa-aa-Ala-Trp-(D-Phe)-Lys have been obtained. To test in vivo the applicability of the activities observed, the receptor assay activity in samples from excretion studies performed after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin was confirmed. Overall results obtained allow to infer structure-activity information for those GHRPs and to detect GHSR1a binding (intact GHRPs plus active metabolites) in excreted urines. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- P Ferro
- Bioanalysis Research Group, Neuroscience Research Program, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain
| | - G Krotov
- Antidoping Centre, Moscow, Russia
| | | | | | - J Segura
- Bioanalysis Research Group, Neuroscience Research Program, IMIM (Hospital del Mar Medical Research Institute), Barcelona, Spain.,Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain
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17
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Metabolomic profiling of urinary changes in mice with monosodium glutamate-induced obesity. Anal Bioanal Chem 2015; 408:567-78. [DOI: 10.1007/s00216-015-9133-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/25/2015] [Accepted: 10/19/2015] [Indexed: 12/27/2022]
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18
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Altabas V, Zjačić-Rotkvić V. Anti-ghrelin antibodies in appetite suppression: recent advances in obesity pharmacotherapy. Immunotargets Ther 2015; 4:123-30. [PMID: 27471718 PMCID: PMC4918252 DOI: 10.2147/itt.s60398] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Obesity is a medical condition caused by accumulated excess body fat with negative impact on patients’ health, including decreased life expectancy. It has become a major health problem in most developed and developing countries, since the worldwide prevalence of obesity nearly doubled during the last 30 years. Consequently, novel treatments focusing on obesity are being investigated. Potential targets include several pathophysiological mechanisms involved in appetite control affecting multiple organ systems, like adipose tissue; some cell types in the stomach and gut; pancreas; thyroid gland; several hypothalamic areas; and centers located in the brainstem. One of the most important orexigenic neuropeptides is ghrelin, which is produced and secreted primarily by ghrelin cells located in the stomach and duodenum. In humans, plasma ghrelin levels rise when the stomach is empty and fall shortly after meal ingestion. In fat tissue, ghrelin increases fat storage. In the brain, it exerts its orexigenic action through activation of NPY/AgRP neurons in the arcuate nucleus. From the pharmacological point of view, it seems that opposing ghrelin activity could be used as a therapeutic principle in treating obesity. The principal idea of antiobesity drugs is to augment anorexigenic and lipolytic signaling, or to block orexigenic and lipogenic mediators. Recent studies have shown that therapeutic vaccines could be a new approach in the development of antiobesity medications. A vaccine should provoke an immune response to a specific causal factor for a particular disease. Several types of anti-ghrelin vaccines have been developed so far, with significant immune response in terms of rising anti-ghrelin antibodies. However, in the only clinical trial performed yet, the results were disappointing, showing no additional weight loss in the study group. Until now, several studies have demonstrated the “proof of concept”, but more studies are required to develop prophylactic and therapeutic vaccines to prevent and/or cure obesity.
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Affiliation(s)
- Velimir Altabas
- Department of Endocrinology, Diabetes and Metabolic Diseases, "Mladen Sekso", Clinic for Internal Medicine, University Hospital Center "Sestre milosrdnice", Zagreb, Croatia
| | - Vanja Zjačić-Rotkvić
- Department of Endocrinology, Diabetes and Metabolic Diseases, "Mladen Sekso", Clinic for Internal Medicine, University Hospital Center "Sestre milosrdnice", Zagreb, Croatia
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19
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Heldsinger A, Grabauskas G, Wu X, Zhou S, Lu Y, Song I, Owyang C. Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation. Endocrinology 2014; 155:3956-69. [PMID: 25060362 PMCID: PMC4164930 DOI: 10.1210/en.2013-2095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.
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Affiliation(s)
- Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48019
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20
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Holubová M, Nagelová V, Lacinová Z, Haluzík M, Sýkora D, Moulin A, Blayo AL, Fehrentz JA, Martinez J, Stofkova A, Jurčovičová J, Zelezná B, Maletínská L. Triazole GHS-R1a antagonists JMV4208 and JMV3002 attenuate food intake, body weight, and adipose tissue mass in mice. Mol Cell Endocrinol 2014; 393:120-8. [PMID: 24953973 DOI: 10.1016/j.mce.2014.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/19/2014] [Accepted: 06/05/2014] [Indexed: 12/29/2022]
Abstract
The only peripherally released orexigenic hormone, ghrelin, plays a key role in food intake and body weight regulation. Antagonizing the ghrelin receptor, GHS-R1a, represents a promising approach for anti-obesity therapy. In our study, two novel GHS-R1a antagonists JMV4208 and JMV3002, which are trisubstituted 1,2,4-triazoles, decreased food intake in fasted lean mice in a dose-dependent manner, with ED50 values of 5.25 and 2.05 mg/kg, respectively. Both compounds were stable in mouse blood, with half-lives of 90 min (JMV4208) and 60 min (JMV3002), and disappeared from the blood 8h after administration. Fourteen days of treatment with the ghrelin antagonists (20 mg/kg twice a day) decreased food intake, body weight and adipose tissue mass in mice with diet-induced obesity (DIO). These results are likely attributable to an impact on food intake reduction and an attenuated expression of the lipogenesis-promoting enzymes (acetyl-CoA carboxylase 1 in subcutaneous fat and fatty acid synthase in subcutaneous and intraperitoneal fat). The decrease in fat mass negatively impacted circulating leptin levels. These data suggest that JMV4208 and JMV3002 could be useful therapeutic agents for the treatment of obesity.
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Affiliation(s)
- M Holubová
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic; Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - V Nagelová
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic
| | - Z Lacinová
- Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - M Haluzík
- Third Department of Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
| | - D Sýkora
- Institute of Chemical Technology, Department of Analytical Chemistry, Prague, Czech Republic
| | - A Moulin
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - A L Blayo
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - J A Fehrentz
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - J Martinez
- IBMM UMR 5274, CNRS - Universités Montpellier 1- Montpellier 2, Faculté de Pharmacie, Montpellier, France
| | - A Stofkova
- Department of Normal, Pathological and Clinical Physiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J Jurčovičová
- Department of Normal, Pathological and Clinical Physiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - B Zelezná
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic
| | - L Maletínská
- Institute of Organic Chemistry and Biochemistry, AS CR, Prague, Czech Republic.
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21
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Lin D, Wang Q, Ran H, Liu K, Wang Y, Wang J, Liu Y, Chen R, Sun Y, Liu R, Ding F. Abnormal response to the anorexic effect of GHS-R inhibitors and exenatide in male Snord116 deletion mouse model for Prader-Willi syndrome. Endocrinology 2014; 155:2355-62. [PMID: 24735326 DOI: 10.1210/en.2013-2083] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Prader-Willi syndrome (PWS) is a genetic disease characterized by persistent hunger and hyperphagia. The lack of the Snord116 small nucleolar RNA cluster has been identified as the major contributor to PWS symptoms. The Snord116 deletion (Snord116del) mouse model manifested a subset of PWS symptoms including hyperphagia and hyperghrelinemia. In this study, male Snord116del mice were characterized and tested for their acute and chronic responses to anorexic substances related to the ghrelin pathway. In comparison with their wild-type littermates, the food intake rate of Snord116del mice was 14% higher when fed ad libitum, and 32% to 49% higher within 12 hours after fasting. Fasted Snord116del mice were less sensitive to the acute anorexic effect of competitive antagonist [d-Lys(3)]-GHRP6, YIL-781, and reverse agonist [d-Arg(1),d-Phe(5),d-Trp(7,9),Leu(11)]-substance P (SPA) of ghrelin receptor GHS-R. All 3 GHS-R inhibitors failed to inhibit chronic food intake of either Snord116del or wild-type mice due to rapid adaptation. Although fasted Snord116del mice had normal sensitivity to the acute anorexic effect of glucagon-like peptide 1 receptor agonist exenatide, those fed ad libitum required a higher dose and more frequent delivery to achieve ∼15% suppression of long-term food intake in comparison with wild-type mice. Ghrelin, however, is unlikely to be essential for the anorexic effect of exenatide in fed mice, as shown by the fact that exenatide did not reduce ghrelin levels in fed mice and food intake of ghrelin(-/-) mice fed ad libitum could be suppressed by exenatide. In conclusion, this study suggests that GHS-R may not be an effective therapeutic target, and in contrast, exenatide may produce anorexic effect in PWS individuals.
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Affiliation(s)
- Dahe Lin
- State Key Laboratory of Cellular Stress Biology (D.L., Q.W., H.R., K.L., Y.W., J.W., Y.L., R.C., R.L., F.D.), School of Life Sciences, Xiamen University, Xiamen 361101, Fujian, China; and Departments of Pediatrics and Molecular and Cellular Biology (Y.S.), Baylor College of Medicine, Houston, Texas 77030
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22
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Kemp BA, Howell NL, Gildea JJ, Padia SH. Intrarenal ghrelin receptor antagonism prevents high-fat diet-induced hypertension in male rats. Endocrinology 2014; 155:2658-66. [PMID: 24797629 DOI: 10.1210/en.2013-2177] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Excess weight gain contributes up to 65% of the risk of primary hypertension, and the increase in blood pressure in response to high-fat diet (HFD) is preceded by significant increases in renal tubular sodium (Na(+)) reabsorption. In normal rats, intrarenal ghrelin infusion increases distal nephron-dependent Na(+) reabsorption via activation of the intrarenal ghrelin receptor (GHSR). This study focusses on the role of intrarenal GHSR-mediated Na(+) reabsorption in HFD-induced hypertension. Dahl salt-sensitive rats received standard diet or HFD for 6 weeks. Rats underwent uninephrectomy and osmotic minipump implantation for chronic intrarenal delivery of vehicle (0.25 μL/h × 28 d), selective GHSR antagonist [D-Lys-3]-growth hormone releasing peptide-6 (0.2μM/d), or GHSR inverse agonist [D-Arg(1), D-Phe(5), D-Trp(7,9), Leu(11)]-substance P (SUB-P) (3.6μM/d). HFD rats with vehicle pumps had significantly increased renal GHSR expression compared with standard diet (0.092 ± 0.005 vs 0.065 ± 0.004 arbitrary units; P < .05), whereas acyl ghrelin levels were similar (16.3±6.2 vs 15.7±8.7 pg/g tissue). HFD rats with vehicle pumps became hypertensive after 2 weeks (P < .05) and showed a significant reduction in 24-hour urine Na(+) before hypertension. At this time, these rats showed an increase in collecting duct α-epithelial Na(+) channel, thereby providing a potential mechanism for the excess Na(+) reabsorption. In contrast, HFD rats with [D-Lys-3]-growth hormone releasing peptide-6 or SUB-P pumps never became hypertensive and did not show the reduction in urine Na(+). Because SUB-P blocks the constitutive, but not ghrelin-dependent, activity of the GHSR, and HFD-induced α-epithelial Na(+) channel up-regulation was abolished during GHSR antagonism, these data suggest that HFD increases the constitutive activity of renal GHSR to increase Na(+) reabsorption and induce hypertension in rats.
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Affiliation(s)
- Brandon A Kemp
- Division of Endocrinology and Metabolism (B.A.K., N.L.H., S.H.P.), Department of Medicine, and Department of Pathology (J.J.G.), University of Virginia School of Medicine, Charlottesville, Virginia 22908-1414
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23
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Özcan B, Neggers SJCMM, Miller AR, Yang HC, Lucaites V, Abribat T, Allas S, Huisman M, Visser JA, Themmen APN, Sijbrands EJG, Delhanty PJD, van der Lely AJ. Does des-acyl ghrelin improve glycemic control in obese diabetic subjects by decreasing acylated ghrelin levels? Eur J Endocrinol 2014; 170:799-807. [PMID: 23864339 DOI: 10.1530/eje-13-0347] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE The objective of this study was to assess the effects of a continuous overnight infusion of des-acyl ghrelin (DAG) on acylated ghrelin (AG) levels and glucose and insulin responses to a standard breakfast meal (SBM) in eight overweight patients with type 2 diabetes. Furthermore, in the same patients and two additional subjects, the effects of DAG infusion on AG concentrations and insulin sensitivity during a hyperinsulinemic-euglycemic clamp (HEC) were assessed. RESEARCH DESIGN AND METHODS A double-blind, placebo-controlled cross-over study design was implemented, using overnight continuous infusions of 3 and 10 μg DAG/kg per h and placebo to study the effects on a SBM. During a HEC, we studied the insulin sensitivity. RESULTS We observed that, compared with placebo, overnight DAG administration significantly decreased postprandial glucose levels, both during continuous glucose monitoring and at peak serum glucose levels. The degree of improvement in glycemia was correlated with baseline plasma AG concentrations. Concurrently, DAG infusion significantly decreased fasting and postprandial AG levels. During the HEC, 2.5 h of DAG infusion markedly decreased AG levels, and the M-index, a measure of insulin sensitivity, was significantly improved in the six subjects in whom we were able to attain steady-state euglycemia. DAG administration was not accompanied by many side effects when compared with placebo. CONCLUSIONS DAG administration improves glycemic control in obese subjects with type 2 diabetes through the suppression of AG levels. DAG is a good candidate for the development of compounds in the treatment of metabolic disorders or other conditions with a disturbed AG:DAG ratio, such as type 2 diabetes mellitus or Prader-Willi syndrome.
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Affiliation(s)
- Behiye Özcan
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Sebastian J C M M Neggers
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Anne Reifel Miller
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Hsiu-Chiung Yang
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Virginia Lucaites
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Thierry Abribat
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Soraya Allas
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Martin Huisman
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Jenny A Visser
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Axel P N Themmen
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Eric J G Sijbrands
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Patric J D Delhanty
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
| | - Aart Jan van der Lely
- Department of Internal MedicineErasmus University Medical Centre, PO Box 2040, 3000 CA, Rotterdam, The NetherlandsLilly Research LaboratoriesLilly Corporate Center, Indianapolis, Indiana 46285, USAAlizé Pharma69 130 Ecully, France
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24
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Affiliation(s)
- Ngoc-Duc Doan
- Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec Canada H3C 3J7
| | - Robert Hopewell
- Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec Canada H3C 3J7
| | - William D. Lubell
- Département de Chimie, Université de Montréal, C.P. 6128, Succursale Centre-Ville, Montréal, Québec Canada H3C 3J7
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Abstract
Obesity is one of the largest and fastest growing public health problems in the world. Last century social changes have set an obesogenic milieu that calls for micro and macro environment interventions for disease prevention, while treatment is mandatory for individuals already obese. The cornerstone of overweight and obesity treatment is diet and physical exercise. However, many patients find lifestyle modifications difficult to comply and prone to failure in the long-term; therefore many patients consider anti-obesity drugs an important adjuvant if not a better alternative to behavioral approach or obesity surgery. Since the pharmacological options for obesity treatment remain quite limited, this is an exciting research area, with new treatment targets and strategies on the horizon. This review discusses the development of innovative therapeutic agents, focusing in energy homeostasis regulation and the use of molecular vaccines, targeting hormones such as somatostatin, GIP and ghrelin, to reduce body weight.
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Affiliation(s)
- Mariana P Monteiro
- Department of Anatomy; Unit for Multidisciplinary Biomedical Research (UMIB); Institute for Biomedical Sciences Abel Salazar (ICBAS); University of Porto; Porto, Portugal
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Heng BC, Aubel D, Fussenegger M. An overview of the diverse roles of G-protein coupled receptors (GPCRs) in the pathophysiology of various human diseases. Biotechnol Adv 2013; 31:1676-94. [DOI: 10.1016/j.biotechadv.2013.08.017] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/19/2013] [Accepted: 08/19/2013] [Indexed: 12/23/2022]
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Heng BC, Aubel D, Fussenegger M. G protein-coupled receptors revisited: therapeutic applications inspired by synthetic biology. Annu Rev Pharmacol Toxicol 2013; 54:227-49. [PMID: 24160705 DOI: 10.1146/annurev-pharmtox-011613-135921] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
G protein-coupled receptors (GPCRs) mediate the majority of cellular responses to hormones and neurotransmitters within the human body. They have much potential in the emerging field of synthetic biology, which is the rational, systematic design of biological systems with desired functionality. The responsiveness of GPCRs to a plethora of endogenous and exogenous ligands and stimuli make them ideal sensory receptor modules of synthetic gene networks. Such networks can activate target gene expression in response to a specific stimulus. Additionally, because GPCRs are important pharmacological targets of various human diseases, genes encoding their protein/peptide ligands can also be incorporated as target genes of the response output elements of synthetic gene networks. This review aims to critically examine the potential role of GPCRs in constructing therapeutic synthetic gene networks and to discuss various challenges in utilizing GPCRs for synthetic biology applications.
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Affiliation(s)
- Boon Chin Heng
- Department of Biosystems Science and Engineering, ETH Zürich, CH-4058 Basel, Switzerland;
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28
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Farkas I, Vastagh C, Sárvári M, Liposits Z. Ghrelin decreases firing activity of gonadotropin-releasing hormone (GnRH) neurons in an estrous cycle and endocannabinoid signaling dependent manner. PLoS One 2013; 8:e78178. [PMID: 24124622 PMCID: PMC3790731 DOI: 10.1371/journal.pone.0078178] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Accepted: 09/16/2013] [Indexed: 12/11/2022] Open
Abstract
The orexigenic peptide, ghrelin is known to influence function of GnRH neurons, however, the direct effects of the hormone upon these neurons have not been explored, yet. The present study was undertaken to reveal expression of growth hormone secretagogue receptor (GHS-R) in GnRH neurons and elucidate the mechanisms of ghrelin actions upon them. Ca2+-imaging revealed a ghrelin-triggered increase of the Ca2+-content in GT1-7 neurons kept in a steroid-free medium, which was abolished by GHS-R-antagonist JMV2959 (10µM) suggesting direct action of ghrelin. Estradiol (1nM) eliminated the ghrelin-evoked rise of Ca2+-content, indicating the estradiol dependency of the process. Expression of GHS-R mRNA was then confirmed in GnRH-GFP neurons of transgenic mice by single cell RT-PCR. Firing rate and burst frequency of GnRH-GFP neurons were lower in metestrous than proestrous mice. Ghrelin (40nM-4μM) administration resulted in a decreased firing rate and burst frequency of GnRH neurons in metestrous, but not in proestrous mice. Ghrelin also decreased the firing rate of GnRH neurons in males. The ghrelin-evoked alterations of the firing parameters were prevented by JMV2959, supporting the receptor-specific actions of ghrelin on GnRH neurons. In metestrous mice, ghrelin decreased the frequency of GABAergic mPSCs in GnRH neurons. Effects of ghrelin were abolished by the cannabinoid receptor type-1 (CB1) antagonist AM251 (1µM) and the intracellularly applied DAG-lipase inhibitor THL (10µM), indicating the involvement of retrograde endocannabinoid signaling. These findings demonstrate that ghrelin exerts direct regulatory effects on GnRH neurons via GHS-R, and modulates the firing of GnRH neurons in an ovarian-cycle and endocannabinoid dependent manner.
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Affiliation(s)
- Imre Farkas
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
| | - Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Miklós Sárvári
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
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Asarian L, Geary N. Sex differences in the physiology of eating. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1215-67. [PMID: 23904103 DOI: 10.1152/ajpregu.00446.2012] [Citation(s) in RCA: 346] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.
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Affiliation(s)
- Lori Asarian
- Institute of Veterinary Physiology and Center for Integrated Human Physiology, University of Zurich, Zurich, Switzerland; and
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30
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Delhanty PJD, Neggers SJ, van der Lely AJ. Mechanisms in endocrinology: Ghrelin: the differences between acyl- and des-acyl ghrelin. Eur J Endocrinol 2012; 167:601-8. [PMID: 22898499 DOI: 10.1530/eje-12-0456] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Des-acyl ghrelin (DAG) is one of the three preproghrelin gene-encoded peptides. Compared with ghrelin and obestatin, it has not received the attention it deserves. DAG has long been considered an inert degradation product of acyl ghrelin (AG). Recent evidence, however, indicates that DAG behaves like a separate hormone. DAG can act together with AG, can antagonize AG, and seems to have AG-independent effects. Therefore, it is believed that DAG must activate its own receptor and that it may also interact with AG at this receptor. Of potential clinical importance is that an increasing number of studies suggest that DAG might be a functional inhibitor of ghrelin and that DAG can suppress ghrelin levels in humans. Therefore, DAG or DAG analogs might be good candidates for future treatment of metabolic disorders or other conditions in which antagonism of AG actions could be beneficial, such as diabetes, obesity, and Prader-Willi syndrome.
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Affiliation(s)
- Patric J D Delhanty
- Department of Medicine, Erasmus University MC, CA Rotterdam, The Netherlands
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