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Kurauti MA, Costa-Júnior JM, Ferreira SM, Dos Santos GJ, Protzek AOP, Nardelli TR, de Rezende LF, Boschero AC. Acute exercise restores insulin clearance in diet-induced obese mice. J Endocrinol 2016; 229:221-32. [PMID: 27000684 DOI: 10.1530/joe-15-0483] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/21/2016] [Indexed: 01/19/2023]
Abstract
The aim of this study was to investigate the insulin clearance in diet-induced obese (DIO) mice submitted to acute endurance exercise (3h of treadmill exercise at 60-70% VO2max). Glucose-stimulated insulin secretion in isolated islets; ipGTT; ipITT; ipPTT; in vivo insulin clearance; protein expression in liver, skeletal muscle, and adipose tissue (insulin degrading enzyme (IDE), insulin receptor subunitβ(IRβ), phospho-Akt (p-Akt) and phospho-AMPK (p-AMPK)), and the activity of IDE in the liver and skeletal muscle were accessed. In DIO mice, acute exercise reduced fasting glycemia and insulinemia, improved glucose and insulin tolerance, reduced hepatic glucose production, and increased p-Akt protein levels in liver and skeletal muscle and p-AMPK protein levels in skeletal muscle. In addition, insulin secretion was reduced, whereas insulin clearance and the expression of IDE and IRβ were increased in liver and skeletal muscle. Finally, IDE activity was increased only in skeletal muscle. In conclusion, we propose that the increased insulin clearance and IDE expression and activity, primarily, in skeletal muscle, constitute an additional mechanism, whereby physical exercise reduces insulinemia in DIO mice.
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Affiliation(s)
- Mirian A Kurauti
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - José M Costa-Júnior
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Sandra M Ferreira
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Gustavo J Dos Santos
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - André O P Protzek
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Tarlliza R Nardelli
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Luiz F de Rezende
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
| | - Antonio C Boschero
- Department of Structural and Functional BiologyInstitute of Biology, State University of Campinas (UNICAMP), Campinas, Brazil
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Protzek AOP, Costa-Júnior JM, Rezende LF, Santos GJ, Araújo TG, Vettorazzi JF, Ortis F, Carneiro EM, Rafacho A, Boschero AC. Augmented β-Cell Function and Mass in Glucocorticoid-Treated Rodents Are Associated with Increased Islet Ir-β /AKT/mTOR and Decreased AMPK/ACC and AS160 Signaling. Int J Endocrinol 2014; 2014:983453. [PMID: 25313308 PMCID: PMC4182854 DOI: 10.1155/2014/983453] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 04/25/2014] [Accepted: 08/17/2014] [Indexed: 12/31/2022] Open
Abstract
Glucocorticoid (GC) therapies may adversely cause insulin resistance (IR) that lead to a compensatory hyperinsulinemia due to insulin hypersecretion. The increased β-cell function is associated with increased insulin signaling that has the protein kinase B (AKT) substrate with 160 kDa (AS160) as an important downstream AKT effector. In muscle, both insulin and AMP-activated protein kinase (AMPK) signaling phosphorylate and inactivate AS160, which favors the glucose transporter (GLUT)-4 translocation to plasma membrane. Whether AS160 phosphorylation is modulated in islets from GC-treated subjects is unknown. For this, two animal models, Swiss mice and Wistar rats, were treated with dexamethasone (DEX) (1 mg/kg body weight) for 5 consecutive days. DEX treatment induced IR, hyperinsulinemia, and dyslipidemia in both species, but glucose intolerance and hyperglycemia only in rats. DEX treatment caused increased insulin secretion in response to glucose and augmented β-cell mass in both species that were associated with increased islet content and increased phosphorylation of the AS160 protein. Protein AKT phosphorylation, but not AMPK phosphorylation, was found significantly enhanced in islets from DEX-treated animals. We conclude that the augmented β-cell function developed in response to the GC-induced IR involves inhibition of the islet AS160 protein activity.
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Affiliation(s)
- André O. P. Protzek
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - José M. Costa-Júnior
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - Luiz F. Rezende
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - Gustavo J. Santos
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - Tiago Gomes Araújo
- School of Medical Sciences, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Jean F. Vettorazzi
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - Fernanda Ortis
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
- Department of Cell and Developmental Biology, Institute of Biomedical Science, University of São Paulo (USP), São Paulo, SP, Brazil
| | - Everardo M. Carneiro
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
| | - Alex Rafacho
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianópolis, SC, Brazil
| | - Antonio C. Boschero
- Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), P.O. Box 6109, 13083-970 Campinas, SP, Brazil
- *Antonio C. Boschero:
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Araújo TG, Oliveira AG, Carvalho BM, Guadagnini D, Protzek AOP, Carvalheira JBC, Boschero AC, Saad MJA. Hepatocyte growth factor plays a key role in insulin resistance-associated compensatory mechanisms. Endocrinology 2012; 153:5760-9. [PMID: 23024263 DOI: 10.1210/en.2012-1496] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Insulin resistance is present in obesity and in type 2 diabetes and is associated with islet cell hyperplasia and hyperinsulinemia, but the driving forces behind this compensatory mechanism are incompletely understood. Previous data have suggested the involvement of an unknown circulating insulin resistance-related β-cell growth factor. In this context, looking for candidates to be a circulating factor, we realized that hepatocyte growth factor (HGF) is a strong candidate as a link between insulin resistance and increased mass of islets/hyperinsulinemia. Our approach aimed to show a possible cause-effect relationship between increase in circulating HGF levels and compensatory islet hyperplasia/hyperinsulinemia by showing the strength of the association, whether or not is a dose-dependent response, the temporality, consistency, plausibility, and reversibility of the association. In this regard, our data showed: 1) a strong and consistent correlation between HGF and the compensatory mechanism in three animal models of insulin resistance; 2) HGF increases β-cell mass in a dose-dependent manner; 3) blocking HGF shuts down the compensatory mechanisms; and 4) an increase in HGF levels seems to precede the compensatory response associated with insulin resistance, indicating that these events occur in a sequential mode. Additionally, blockages of HGF receptor (Met) worsen the impaired insulin-induced insulin signaling in liver of diet-induced obesity rats. Overall, our data indicate that HGF is a growth factor playing a key role in islet mass increase and hyperinsulinemia in diet-induced obesity rats and suggest that the HGF-Met axis may have a role on insulin signaling in the liver.
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Affiliation(s)
- Tiago G Araújo
- Department of Internal Medicine, State University of Campinas, Campinas, 13081-970 São Paulo, Brazil
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Protzek AOP, Rafacho A, Viscelli BA, Bosqueiro JR, Cappelli AP, Paula FMM, Boschero AC, Pinheiro EC. Insulin and glucose sensitivity, insulin secretion and beta-cell distribution in endocrine pancreas of the fruit bat Artibeus lituratus. Comp Biochem Physiol A Mol Integr Physiol 2010; 157:142-8. [PMID: 20566319 DOI: 10.1016/j.cbpa.2010.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 05/28/2010] [Accepted: 05/31/2010] [Indexed: 10/19/2022]
Abstract
The fruit bat Artibeus lituratus absorbs large amounts of glucose in short periods of time and maintains normoglycemia even after a prolonged starvation period. Based on these data, we aimed to investigate various aspects related with glucose homeostasis analyzing: blood glucose and insulin levels, intraperitoneal glucose and insulin tolerance tests (ipGTT and ipITT), glucose-stimulated insulin secretion (2.8, 5.6 or 8.3 mmol/L glucose) in pancreas fragments, cellular distribution of beta cells, and the amount of pAkt/Akt in the pectoral muscle and liver. Blood glucose levels were higher in fed bats (6.88+/-0.5 mmol/L) than fasted bats (4.0+/-0.8 mmol/L), whereas insulin levels were similar in both conditions. The values of the area-under-the curve obtained from ipGTT were significantly higher when bats received 2 (5.5-fold) or 3g/kg glucose (7.5-fold) b.w compared to control (saline). These bats also exhibited a significant decrease of blood glucose values after insulin administration during the ipITT. Insulin secretion from fragments of pancreas under physiological concentrations of glucose (5.6 or 8.3 mmol/L) was similar but higher than in 2.8 mmol/L glucose 1.8- and 2.0-fold, respectively. These bats showed a marked beta-cell distribution along the pancreas, and the pancreatic beta cells are not exclusively located at the central part of the islet. The insulin-induced Akt phosphorylation was more pronounced in the pectoral muscle, compared to liver. The high sensitivity to glucose and insulin, the proper insulin response to glucose, and the presence of an apparent large beta-cell population could represent benefits for the management of high influx of glucose from a carbohydrate-rich meal, which permits appropriate glucose utilization.
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Affiliation(s)
- A O P Protzek
- Department of Physiological Sciences, Institute of Biological Science, University of Brasília, DF, Brazil.
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