1
|
Kabir M, Bergman RN, Porter J, Stefanovski D, Paszkiewicz RL, Piccinini F, Woolcott OO, Yang H, Sashi Gopaul V, Stiles L, Kolka CM. Dapagliflozin prevents abdominal visceral and subcutaneous adipose tissue dysfunction in the insulin-resistant canine model. Obesity (Silver Spring) 2023; 31:1798-1811. [PMID: 37221655 PMCID: PMC10981466 DOI: 10.1002/oby.23771] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 02/14/2023] [Accepted: 02/16/2023] [Indexed: 05/25/2023]
Abstract
OBJECTIVE Sodium-glucose cotransporter 2 inhibitors (SGLT2i) promote urinary glucose excretion, induce weight loss, and reduce fat accumulation. The effects of the SGLT2i dapagliflozin (DAPA) on subcutaneous (SC) and visceral (VIS) adipose tissue function remain unclear. The objective of this study is to evaluate SC and VIS adipose tissue function in an insulin-resistant canine model. METHODS A total of 12 dogs were fed a high-fat diet (HFD) for 6 weeks and then were given a single low dose of streptozotocin (18.5 mg/kg) to induce insulin resistance. Animals were then randomized and exposed to DAPA (n = 6, 1.25 mg/kg) or placebo (n = 6) once per day for 6 weeks while remaining on the HFD. RESULTS DAPA prevented further weight gain induced by the HFD and normalized fat mass. DAPA reduced fasting glucose and increased free fatty acids, adiponectin, and β-hydroxybutyrate. DAPA reduced adipocyte diameter and cell distribution. Furthermore, DAPA increased genes associated with beiging, lipolysis, and adiponectin secretion and the expression of the adiponectin receptor ADR2, in SC and VIS adipose tissue. DAPA increased AMP-activated protein kinase activity and maximal mitochondrial respiratory function, especially in the SC depot. Furthermore, DAPA reduced cytokines and ceramide synthesis enzymes in SC and VIS depots. CONCLUSIONS For the first time, to our knowledge, we identify mechanisms by which DAPA enhances adipose tissue function in regulating energy homeostasis in an insulin-resistant canine model.
Collapse
Affiliation(s)
- Morvarid Kabir
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - Richard N Bergman
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - Jay Porter
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - Darko Stefanovski
- University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA
| | - Rebecca L Paszkiewicz
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - Francesca Piccinini
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - Orison O. Woolcott
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| | - HsiuChiung Yang
- Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca Gothenburg, Sweden
| | - V Sashi Gopaul
- Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca Gothenburg, Sweden
| | - Linsey Stiles
- Department of Endocrinology, David Geffen School of Medicine at the University of California, Los Angeles, CA, USA
| | - Cathryn M Kolka
- Cedars-Sinai Medical Center, Diabetes and Obesity Research Institute, Los Angeles, California, USA
| |
Collapse
|
2
|
Molendijk J, Kolka CM, Cairns H, Brosda S, Mohamed A, Shah AK, Brown I, Hodson MP, Hennessy T, Liu G, Stoll T, Richards RS, Gartside M, Patel K, Clemons NJ, Phillips WA, Barbour A, Westerhuis JA, Hill MM. Elevation of fatty acid desaturase 2 in esophageal adenocarcinoma increases polyunsaturated lipids and may exacerbate bile acid-induced DNA damage. Clin Transl Med 2022; 12:e810. [PMID: 35560527 PMCID: PMC9099135 DOI: 10.1002/ctm2.810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 03/22/2022] [Accepted: 03/27/2022] [Indexed: 12/04/2022] Open
Abstract
Background The risk of esophageal adenocarcinoma (EAC) is associated with gastro‐esophageal reflux disease (GERD) and obesity. Lipid metabolism‐targeted therapies decrease the risk of progressing from Barrett's esophagus (BE) to EAC, but the precise lipid metabolic changes and their roles in genotoxicity during EAC development are yet to be established. Methods Esophageal biopsies from the normal epithelium (NE), BE, and EAC, were analyzed using concurrent lipidomics and proteomics (n = 30) followed by orthogonal validation on independent samples using RNAseq transcriptomics (n = 22) and immunohistochemistry (IHC, n = 80). The EAC cell line FLO‐1 was treated with FADS2 selective inhibitor SC26196, and/or bile acid cocktail, followed by immunofluorescence staining for γH2AX. Results Metabolism‐focused Reactome analysis of the proteomics data revealed enrichment of fatty acid metabolism, ketone body metabolism, and biosynthesis of specialized pro‐resolving mediators in EAC pathogenesis. Lipidomics revealed progressive alterations (NE‐BE‐EAC) in glycerophospholipid synthesis with decreasing triglycerides and increasing phosphatidylcholine and phosphatidylethanolamine, and sphingolipid synthesis with decreasing dihydroceramide and increasing ceramides. Furthermore, a progressive increase in lipids with C20 fatty acids and polyunsaturated lipids with ≥4 double bonds were also observed. Integration with transcriptome data identified candidate enzymes for IHC validation: Δ4‐Desaturase, Sphingolipid 1 (DEGS1) which desaturates dihydroceramide to ceramide, and Δ5 and Δ6‐Desaturases (fatty acid desaturases, FADS1 and FADS2), responsible for polyunsaturation. All three enzymes showed significant increases from BE through dysplasia to EAC, but transcript levels of DEGS1 were decreased suggesting post‐translational regulation. Finally, the FADS2 selective inhibitor SC26196 significantly reduced polyunsaturated lipids with three and four double bonds and reduced bile acid‐induced DNA double‐strand breaks in FLO‐1 cells in vitro. Conclusions Integrated multiomics revealed sphingolipid and phospholipid metabolism rewiring during EAC development. FADS2 inhibition and reduction of the high polyunsaturated lipids effectively protected EAC cells from bile acid‐induced DNA damage in vitro, potentially through reduced lipid peroxidation.
Collapse
Affiliation(s)
- Jeffrey Molendijk
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia.,Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Cathryn M Kolka
- Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Henry Cairns
- Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Sandra Brosda
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia
| | - Ahmed Mohamed
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia.,Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Alok K Shah
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia.,Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | | | - Mark P Hodson
- School of Pharmacy, The University of Queensland, Woolloongabba, Australia
| | - Thomas Hennessy
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia.,Agilent Technologies, Mulgrave, Australia
| | - Guanghao Liu
- Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Thomas Stoll
- Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Renee S Richards
- Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| | - Michael Gartside
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia
| | - Kalpana Patel
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia
| | - Nicholas J Clemons
- Division of Cancer Research, Peter MacCallum Cancer Centre, Melbourne, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Wayne A Phillips
- Division of Cancer Research, Peter MacCallum Cancer Centre, Melbourne, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia
| | - Andrew Barbour
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia
| | - Johan A Westerhuis
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Michelle M Hill
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Woolloongabba, Australia.,Precision and Systems Biomedicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Australia
| |
Collapse
|
3
|
Kolka CM, Webster J, Lepletier A, Winterford C, Brown I, Richards RS, Zelek WM, Cao Y, Khamis R, Shanmugasundaram KB, Wuethrich A, Trau M, Brosda S, Barbour A, Shah AK, Eslick GD, Clemons NJ, Morgan BP, Hill MM. C5b-9 Membrane Attack Complex Formation and Extracellular Vesicle Shedding in Barrett's Esophagus and Esophageal Adenocarcinoma. Front Immunol 2022; 13:842023. [PMID: 35345676 PMCID: PMC8957096 DOI: 10.3389/fimmu.2022.842023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/10/2022] [Indexed: 02/05/2023] Open
Abstract
The early complement components have emerged as mediators of pro-oncogenic inflammation, classically inferred to cause terminal complement activation, but there are limited data on the activity of terminal complement in cancer. We previously reported elevated serum and tissue C9, the terminal complement component, in esophageal adenocarcinoma (EAC) compared to the precursor condition Barrett’s Esophagus (BE) and healthy controls. Here, we investigate the level and cellular fates of the terminal complement complex C5b-9, also known as the membrane attack complex. Punctate C5b-9 staining and diffuse C9 staining was detected in BE and EAC by multiplex immunohistofluorescence without corresponding increase of C9 mRNA transcript. Increased C9 and C5b-9 staining were observed in the sequence normal squamous epithelium, BE, low- and high-grade dysplasia, EAC. C5b-9 positive esophageal cells were morphologically intact, indicative of sublytic or complement-evasion mechanisms. To investigate this at a cellular level, we exposed non-dysplastic BE (BAR-T and CP-A), high-grade dysplastic BE (CP-B and CP-D) and EAC (FLO-1 and OE-33) cell lines to the same sublytic dose of immunopurified human C9 (3 µg/ml) in the presence of C9-depleted human serum. Cellular C5b-9 was visualized by immunofluorescence confocal microscopy. Shed C5b-9 in the form of extracellular vesicles (EV) was measured in collected conditioned medium using recently described microfluidic immunoassay with capture by a mixture of three tetraspanin antibodies (CD9/CD63/CD81) and detection by surface-enhanced Raman scattering (SERS) after EV labelling with C5b-9 or C9 antibody conjugated SERS nanotags. Following C9 exposure, all examined cell lines formed C5b-9, internalized C5b-9, and shed C5b-9+ and C9+ EVs, albeit at varying levels despite receiving the same C9 dose. In conclusion, these results confirm increased esophageal C5b-9 formation during EAC development and demonstrate capability and heterogeneity in C5b-9 formation and shedding in BE and EAC cell lines following sublytic C9 exposure. Future work may explore the molecular mechanisms and pathogenic implications of the shed C5b-9+ EV.
Collapse
Affiliation(s)
- Cathryn M Kolka
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Julie Webster
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Ailin Lepletier
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Clay Winterford
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Ian Brown
- Envoi Pathology, Herston, QLD, Australia
| | - Renee S Richards
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Wioleta M Zelek
- Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Yilang Cao
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Ramlah Khamis
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, St Lucia, QLD, Australia
| | - Karthik B Shanmugasundaram
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, St Lucia, QLD, Australia
| | - Alain Wuethrich
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, St Lucia, QLD, Australia
| | - Matt Trau
- Centre for Personalised Nanomedicine, Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, St Lucia, QLD, Australia.,School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Sandra Brosda
- University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Andrew Barbour
- University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Alok K Shah
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Guy D Eslick
- National Health and Medical Research Council (NHMRC) Centre of Research Excellence in Digestive Health, Hunter Medical Research Institute, The University of Newcastle, Newcastle, NSW, Australia
| | - Nicholas J Clemons
- Cancer Research Division, Peter MaCallum Cancer Centre, Melbourne VIC, Australia.,Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, VIC, Australia
| | - B Paul Morgan
- Division of Infection & Immunity, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Michelle M Hill
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia.,University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| |
Collapse
|
4
|
Krueger A, Mohamed A, Kolka CM, Stoll T, Zaugg J, Linedale R, Morrison M, Soyer HP, Hugenholtz P, Frazer IH, Hill MM. Skin Cancer-Associated S. aureus Strains Can Induce DNA Damage in Human Keratinocytes by Downregulating DNA Repair and Promoting Oxidative Stress. Cancers (Basel) 2022; 14:2143. [PMID: 35565272 PMCID: PMC9106025 DOI: 10.3390/cancers14092143] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 12/19/2022] Open
Abstract
Actinic keratosis (AK) is a premalignant lesion, common on severely photodamaged skin, that can progress over time to cutaneous squamous cell carcinoma (SCC). A high bacterial load of Staphylococcus aureus is associated with AK and SCC, but it is unknown whether this has a direct impact on skin cancer development. To determine whether S. aureus can have cancer-promoting effects on skin cells, we performed RNA sequencing and shotgun proteomics on primary human keratinocytes after challenge with sterile culture supernatant ('secretome') from four S. aureus clinical strains isolated from AK and SCC. Secretomes of two of the S. aureus strains induced keratinocytes to overexpress biomarkers associated with skin carcinogenesis and upregulated the expression of enzymes linked to reduced skin barrier function. Further, these strains induced oxidative stress markers and all secretomes downregulated DNA repair mechanisms. Subsequent experiments on an expanded set of lesion-associated S. aureus strains confirmed that exposure to their secretomes led to increased oxidative stress and DNA damage in primary human keratinocytes. A significant correlation between the concentration of S. aureus phenol soluble modulin toxins in secretome and the secretome-induced level of oxidative stress and genotoxicity in keratinocytes was observed. Taken together, these data demonstrate that secreted compounds from lesion-associated clinical isolates of S. aureus can have cancer-promoting effects in keratinocytes that may be relevant to skin oncogenesis.
Collapse
Affiliation(s)
- Annika Krueger
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia; (A.K.); (R.L.); (M.M.); (I.H.F.)
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD 4006, Australia; (A.M.); (C.M.K.); (T.S.)
| | - Ahmed Mohamed
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD 4006, Australia; (A.M.); (C.M.K.); (T.S.)
| | - Cathryn M. Kolka
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD 4006, Australia; (A.M.); (C.M.K.); (T.S.)
| | - Thomas Stoll
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD 4006, Australia; (A.M.); (C.M.K.); (T.S.)
| | - Julian Zaugg
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia; (J.Z.); (P.H.)
| | - Richard Linedale
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia; (A.K.); (R.L.); (M.M.); (I.H.F.)
| | - Mark Morrison
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia; (A.K.); (R.L.); (M.M.); (I.H.F.)
| | - H. Peter Soyer
- Dermatology Research Centre, The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD 4102, Australia;
- Dermatology Department, Princess Alexandra Hospital, Brisbane, QLD 4102, Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia; (J.Z.); (P.H.)
| | - Ian H. Frazer
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia; (A.K.); (R.L.); (M.M.); (I.H.F.)
| | - Michelle M. Hill
- The University of Queensland Diamantina Institute, Faculty of Medicine, The University of Queensland, Translational Research Institute, Woolloongabba, QLD 4102, Australia; (A.K.); (R.L.); (M.M.); (I.H.F.)
- QIMR Berghofer Medical Research Institute, Herston, Brisbane, QLD 4006, Australia; (A.M.); (C.M.K.); (T.S.)
- The University of Queensland Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Herston, QLD 4006, Australia
| |
Collapse
|
5
|
Brouwer A, Asare Bediako I, Paszkiewicz RL, Kolka CM, Bergman RN, Broussard JL. Impact of sleep deprivation and high-fat feeding on insulin sensitivity and beta cell function in dogs. Diabetologia 2020; 63:875-884. [PMID: 32016566 PMCID: PMC7304935 DOI: 10.1007/s00125-019-05084-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/06/2019] [Indexed: 12/15/2022]
Abstract
AIMS/HYPOTHESIS Insufficient sleep is increasingly recognised as a major risk factor for the development of obesity and diabetes, and short-term sleep loss in clinical studies leads to a reduction in insulin sensitivity. Sleep loss-induced metabolic impairments are clinically relevant, since reductions in insulin sensitivity after sleep loss are comparable to insulin sensitivity differences between healthy individuals and those with impaired glucose tolerance. However, the relative effects of sleep loss vs high-fat feeding in the same individual have not been assessed. In addition, to our knowledge no diurnal (active during the daytime) non-human mammalian model of sleep loss-induced metabolic impairment exists, which limits our ability to study links between sleep and metabolism. METHODS This study examined the effects of one night of total sleep deprivation on insulin sensitivity and beta cell function, as assessed by an IVGTT, before and after 9 months of high-fat feeding in a canine model. RESULTS One night of total sleep deprivation in lean dogs impaired insulin sensitivity to a similar degree as a chronic high-fat diet (HFD)(normal sleep: 4.95 ± 0.45 mU-1 l-1 min-1; sleep deprivation: 3.14 ± 0.21 mU-1 l-1 min-1; HFD: 3.74 ± 0.48 mU-1 l-1 min-1; mean ± SEM). Hyperinsulinaemic compensation was induced by the chronic HFD, suggesting adequate beta cell response to high-fat feeding. In contrast, there was no beta cell compensation after one night of sleep deprivation, suggesting that there was metabolic dysregulation with acute sleep loss that, if sustained during chronic sleep loss, could contribute to the risk of type 2 diabetes. After chronic high-fat feeding, acute total sleep deprivation did not cause further impairments in insulin sensitivity (sleep deprivation + chronic HFD: 3.28 mU-1 l-1 min-1). CONCLUSIONS/INTERPRETATION Our findings provide further evidence that sleep is important for metabolic health and establish a diurnal animal model of metabolic disruption during insufficient sleep.
Collapse
Affiliation(s)
- Annelies Brouwer
- Sleep and Metabolism Laboratory, Department of Health and Exercise Science, Colorado State University, 1582 Campus Delivery, Fort Collins, CO, 80523-1582, USA
- Amsterdam UMC, Vrije Universiteit, Department of Psychiatry, Amsterdam Public Health Research Institute, Amsterdam, the Netherlands
- GGZ inGeest Specialized Mental Health Care, Amsterdam, the Netherlands
| | - Isaac Asare Bediako
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Rebecca L Paszkiewicz
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Josiane L Broussard
- Sleep and Metabolism Laboratory, Department of Health and Exercise Science, Colorado State University, 1582 Campus Delivery, Fort Collins, CO, 80523-1582, USA.
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| |
Collapse
|
6
|
Bergman RN, Piccinini F, Kabir M, Kolka CM, Ader M. Erratum. Hypothesis: Role of Reduced Hepatic Insulin Clearance in the Pathogenesis of Type 2 Diabetes. Diabetes 2019;68:1709-1716. Diabetes 2019; 68:2350. [PMID: 31597638 PMCID: PMC6969554 DOI: 10.2337/db19-er12a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
7
|
Kolka CM. The vascular endothelium plays a role in insulin action. Clin Exp Pharmacol Physiol 2019; 47:168-175. [PMID: 31479553 DOI: 10.1111/1440-1681.13171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/23/2019] [Accepted: 08/27/2019] [Indexed: 12/30/2022]
Abstract
The endocrine system relies on the vasculature for delivery of hormones throughout the body, and the capillary microvasculature is the site where the hormones cross from the blood into the target tissue. Once considered an inert wall, various studies have now highlighted the functions of the capillary endothelium to regulate transport and therefore affect or maintain the interstitial environment. The role of the capillary may be clear in areas where there is a continuous endothelium, yet there also appears to be a role of endothelial cells in tissues with a sinusoidal structure. Here we focused on the most common endocrine disorder, diabetes, and several of the target organs associated with the disease, including skeletal muscle, liver and pancreas. However, it is important to note that the ability of hormones to cross the endothelium to reach their target tissue is a component of all endocrine functions. It is also a consideration in organs throughout the body and may have greater impact for larger hormones with target tissues containing a continuous endothelium. We noted that the blood levels do not always equal interstitial levels, which is what the cells are exposed to, and discussed how this may change in diseases such as obesity and insulin resistance. The capillary endothelium is, therefore, an essential and understudied aspect of endocrinology and metabolism that can be altered in disease, which may be an appropriate target for treatment.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Department of Biomedical Science, Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| |
Collapse
|
8
|
Bergman RN, Piccinini F, Kabir M, Kolka CM, Ader M. Hypothesis: Role of Reduced Hepatic Insulin Clearance in the Pathogenesis of Type 2 Diabetes. Diabetes 2019; 68:1709-1716. [PMID: 31431441 PMCID: PMC6702636 DOI: 10.2337/db19-0098] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/02/2019] [Indexed: 12/19/2022]
Abstract
There is wide variance among individuals in the fraction of insulin cleared by the liver (20% to 80%). Hepatic insulin clearance is 67% lower in African Americans than European Americans. Clearance is also lower in African American children 7-13 years of age. Lower hepatic insulin clearance will result in peripheral hyperinsulinemia: this exacerbates insulin resistance, which stresses the β-cells, possibly resulting in their ultimate failure and onset of type 2 diabetes. We hypothesize that lower insulin clearance can be a primary cause of type 2 diabetes in at-risk individuals.
Collapse
Affiliation(s)
- Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Francesca Piccinini
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Morvarid Kabir
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Marilyn Ader
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| |
Collapse
|
9
|
Iyer MS, Paszkiewicz RL, Bergman RN, Richey JM, Woolcott OO, Asare-Bediako I, Wu Q, Kim SP, Stefanovski D, Kolka CM, Clegg DJ, Kabir M. Activation of NPRs and UCP1-independent pathway following CB1R antagonist treatment is associated with adipose tissue beiging in fat-fed male dogs. Am J Physiol Endocrinol Metab 2019; 317:E535-E547. [PMID: 31237449 PMCID: PMC6766608 DOI: 10.1152/ajpendo.00539.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 11/22/2022]
Abstract
CB1 receptor (CB1R) antagonism improves the deleterious effects of a high-fat diet (HFD) by reducing body fat mass and adipocyte cell size. Previous studies demonstrated that the beneficial effects of the CB1R antagonist rimonabant (RIM) in white adipose tissue (WAT) are partially due to an increase of mitochondria numbers and upregulation thermogenesis markers, suggesting an induction of WAT beiging. However, the molecular mechanism by which CB1R antagonism induces weight loss and WAT beiging is unclear. In this study, we probed for genes associated with beiging and explored longitudinal molecular mechanisms by which the beiging process occurs. HFD dogs received either RIM (HFD+RIM) or placebo (PL) (HFD+PL) for 16 wk. Several genes involved in beiging were increased in HFD+RIM compared with pre-fat, HFD, and HFD+PL. We evaluated lipolysis and its regulators including natriuretic peptide (NP) and its receptors (NPRs), β-1 and β-3 adrenergic receptor (β1R, β3R) genes. These genes were increased in WAT depots, accompanied by an increase in lipolysis in HFD+RIM. In addition, RIM decreased markers of inflammation and increased adiponectin receptors in WAT. We observed a small but significant increase in UCP1; therefore, we evaluated the newly discovered UCP1-independent thermogenesis pathway. We confirmed that SERCA2b and RYR2, the two key genes involved in this pathway, were upregulated in the WAT. Our data suggest that the upregulation of NPRs, β-1R and β-3R, lipolysis, and SERCA2b and RYR2 may be one of the mechanisms by which RIM promotes beiging and overall the improvement of metabolic homeostasis induced by RIM.
Collapse
MESH Headings
- Adipose Tissue/drug effects
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, White/drug effects
- Animals
- Diet, High-Fat/adverse effects
- Dogs
- Gene Expression/drug effects
- Inflammation/pathology
- Inflammation/prevention & control
- Insulin Resistance
- Male
- Organelle Biogenesis
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/metabolism
- Receptors, Atrial Natriuretic Factor/drug effects
- Rimonabant/pharmacology
- Thermogenesis/drug effects
- Thermogenesis/genetics
- Uncoupling Protein 1/drug effects
- Weight Loss/drug effects
Collapse
Affiliation(s)
- Malini S Iyer
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | | | - Richard N Bergman
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Joyce M Richey
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Orison O Woolcott
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Isaac Asare-Bediako
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Qiang Wu
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Stella P Kim
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Darko Stefanovski
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Cathryn M Kolka
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Deborah J Clegg
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| | - Morvarid Kabir
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California
| |
Collapse
|
10
|
Asare-Bediako I, Paszkiewicz RL, Kim SP, Woolcott OO, Kolka CM, Burch M, Kabir M, Piccinini F, Bergman RN. Assessment of hepatic insulin extraction from in vivo surrogate methods of insulin clearance measurement. Am J Physiol Endocrinol Metab 2018; 315:E605-E612. [PMID: 29509434 PMCID: PMC6230713 DOI: 10.1152/ajpendo.00344.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Hyperinsulinemia, accompanied by reduced first-pass hepatic insulin extraction (FPE) and increased secretion, is a primary response to insulin resistance. Different in vivo methods are used to estimate the clearance of insulin, which is assumed to reflect FPE. We compared two methodologically different but commonly used indirect estimates with directly measured FPE in healthy dogs ( n = 9). The indirect methods were 1) metabolic clearance rate of insulin (MCR) during the hyperinsulinemic-euglycemic clamp (EGC), a steady-state method, and 2) fractional clearance rate of insulin (FCR) during the frequently sampled intravenous glucose tolerance test (FSIGT), a dynamic method. MCR was calculated as the ratio of insulin infusion rate to steady-state plasma insulin. FCR was calculated as the exponential decay rate constant of the injected insulin. Directly measured FPE is based on the difference in insulin measurements during intraportal vs. peripheral vein insulin infusions. We found a strong correlation between indirect FCR (min-1) and FPE (%). In contrast, we observed a poor association between MCR (ml·min-1·kg-1) and FPE (%). Our findings in canines suggest that FCR measured during FSIGT can be used to estimate FPE. However, MCR calculated during EGC appears to be a poor surrogate for FPE.
Collapse
Affiliation(s)
- Isaac Asare-Bediako
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | | | - Stella P Kim
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | - Orison O Woolcott
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | - Cathryn M Kolka
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | - Miguel Burch
- Cedars-Sinai Medical Center, Department of Surgery , Los Angeles, California
| | - Morvarid Kabir
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | - Francesca Piccinini
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| | - Richard N Bergman
- Cedars-Sinai Diabetes and Obesity Research Institute , Los Angeles, California
| |
Collapse
|
11
|
Asare-Bediako I, Paszkiewicz RL, Kim SP, Woolcott OO, Kolka CM, Burch MA, Kabir M, Bergman RN. Variability of Directly Measured First-Pass Hepatic Insulin Extraction and Its Association With Insulin Sensitivity and Plasma Insulin. Diabetes 2018; 67:1495-1503. [PMID: 29752425 PMCID: PMC6054441 DOI: 10.2337/db17-1520] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/03/2018] [Indexed: 01/20/2023]
Abstract
Although the β-cells secrete insulin, the liver, with its first-pass insulin extraction (FPE), regulates the amount of insulin allowed into circulation for action on target tissues. The metabolic clearance rate of insulin, of which FPE is the dominant component, is a major determinant of insulin sensitivity (SI). We studied the intricate relationship among FPE, SI, and fasting insulin. We used a direct method of measuring FPE, the paired portal/peripheral infusion protocol, where insulin is infused stepwise through either the portal vein or a peripheral vein in healthy young dogs (n = 12). FPE is calculated as the difference in clearance rates (slope of infusion rate vs. steady insulin plot) between the paired experiments. Significant correlations were found between FPE and clamp-assessed SI (rs = 0.74), FPE and fasting insulin (rs = -0.64), and SI and fasting insulin (rs = -0.67). We also found a wide variance in FPE (22.4-77.2%; mean ± SD 50.4 ± 19.1) that is reflected in the variability of plasma insulin (48.1 ± 30.9 pmol/L) and SI (9.4 ± 5.8 × 104 dL · kg-1 · min-1 · [pmol/L]-1). FPE could be the nexus of regulation of both plasma insulin and SI.
Collapse
Affiliation(s)
| | | | - Stella P Kim
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA
| | - Orison O Woolcott
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA
| | - Cathryn M Kolka
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA
| | - Miguel A Burch
- Cedars-Sinai Medical Center, Department of Surgery, Los Angeles, CA
| | - Morvarid Kabir
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA
| | - Richard N Bergman
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA
| |
Collapse
|
12
|
Broussard JL, Bergman RN, Bediako IA, Paszkiewicz RL, Iyer MS, Kolka CM. Insulin Access to Skeletal Muscle is Preserved in Obesity Induced by Polyunsaturated Diet. Obesity (Silver Spring) 2018; 26:119-125. [PMID: 29193779 PMCID: PMC5739979 DOI: 10.1002/oby.22057] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 01/06/2023]
Abstract
OBJECTIVE Diets high in saturated fat induce obesity and insulin resistance and impair insulin access to skeletal muscle, leading to reduced insulin levels at the muscle cell surface available to bind insulin receptors and induce glucose uptake. In contrast, diets supplemented with polyunsaturated fat improve insulin sensitivity (SI) and reduce the risk for type 2 diabetes. It was hypothesized that a diet high in polyunsaturated fat would preserve SI and insulin access to muscle, as compared with a diet high in saturated fat. METHODS After 12 weeks of control, saturated (LARD), or polyunsaturated (salmon oil [SO]) high-fat diet feeding, muscle SI and insulin access to skeletal muscle were measured by using lymph, a surrogate of skeletal muscle interstitial fluid. RESULTS Both high-fat diets induced similar weight gain, yet only LARD impaired SI. Hyperinsulinemia in the LARD group did not induce an increase in basal interstitial insulin, suggesting reduced insulin access to muscle after LARD, but not after SO. CONCLUSIONS A diet high in polyunsaturated fat does not impair insulin access to muscle interstitium or induce insulin resistance as observed with a saturated fat diet, despite similar weight gain. Future studies should determine whether dietary SO supplementation improves impairments in insulin access to skeletal muscle.
Collapse
Affiliation(s)
- Josiane L Broussard
- Department of Integrated Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Isaac Asare Bediako
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Rebecca L Paszkiewicz
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Malini S Iyer
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA
| |
Collapse
|
13
|
Abstract
Introduction Anesthesia induces insulin resistance, which may contribute to elevated blood glucose and adverse post-operative outcomes in critically ill patients, and impair glycemic control in surgical patients with diabetes. However, little is known about the mechanisms by which anesthesia impairs insulin sensitivity. Here we investigate the effects of anesthesia on insulin sensitivity in metabolic tissues. Methods Hyperinsulinemic-euglycemic clamps were performed in 32 lean (control diet; n = 16 conscious versus n = 16 anesthetized) and 24 fat-fed (6 weeks fat-feeding; n = 16 conscious versus n = 8 anesthetized) adult male mongrel dogs in conjunction with tracer methodology to differentiate hepatic versus peripheral insulin sensitivity. Propofol was administered as an intravenous bolus (3mg/kg) to initiate anesthesia, which was then maintained with inhaled sevoflurane or isoflurane (2–3%) for the duration of the procedure. Results Anesthesia reduced peripheral insulin sensitivity by approximately 50% in both lean and fat-fed animals as compared to conscious animals, and insulin action at the liver was almost completely suppressed during anesthesia such that hepatic insulin sensitivity was decreased by 75.5% and; 116.2% in lean and fat-fed groups, respectively. Conclusion Inhaled anesthesia induces severe hepatic insulin resistance in a canine model. Countermeasures that preserve hepatic insulin sensitivity may represent a therapeutic target that could improve surgical outcomes in both diabetic and healthy patients.
Collapse
Affiliation(s)
- Stella P. Kim
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, United States of America
| | - Josiane L. Broussard
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, United States of America
| | - Cathryn M. Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, United States of America
- * E-mail:
| |
Collapse
|
14
|
Broussard JL, Castro AVB, Iyer M, Paszkiewicz RL, Bediako IA, Szczepaniak LS, Szczepaniak EW, Bergman RN, Kolka CM. Insulin access to skeletal muscle is impaired during the early stages of diet-induced obesity. Obesity (Silver Spring) 2016; 24:1922-8. [PMID: 27569119 PMCID: PMC5004780 DOI: 10.1002/oby.21562] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/06/2016] [Accepted: 04/28/2016] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Insulin must move from the blood to the interstitium to initiate signaling, yet access to the interstitium may be impaired in cases of insulin resistance, such as obesity. This study investigated whether consuming a short- and long-term high-fat diet (HFD) impairs insulin access to skeletal muscle, the major site of insulin-mediated glucose uptake. METHODS Male mongrel dogs were divided into three groups consisting of control diet (n = 16), short-term (n = 8), and long-term HFD (n = 8). Insulin sensitivity was measured with intravenous glucose tolerance tests. A hyperinsulinemic euglycemic clamp was performed in each animal at the conclusion of the study. During the clamp, lymph fluid was measured as a representation of the interstitial space to assess insulin access to muscle. RESULTS Short- and long-term HFD induced obesity and reduced insulin sensitivity. Lymph insulin concentrations were approximately 50% of plasma insulin concentrations under control conditions. Long-term HFD caused fasting plasma hyperinsulinemia; however, interstitial insulin concentrations were not increased, suggesting impaired insulin access to muscle. CONCLUSIONS A HFD rapidly induces insulin resistance at the muscle and impairs insulin access under basal insulin concentrations. Hyperinsulinemia induced by a long-term HFD may be a compensatory mechanism necessary to maintain healthy insulin levels in muscle interstitium.
Collapse
Affiliation(s)
- Josiane L Broussard
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ana V B Castro
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Malini Iyer
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Rebecca L Paszkiewicz
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Isaac Asare Bediako
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | | | | | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| |
Collapse
|
15
|
Broussard JL, Nelson MD, Kolka CM, Bediako IA, Paszkiewicz RL, Smith L, Szczepaniak EW, Stefanovski D, Szczepaniak LS, Bergman RN. Rapid development of cardiac dysfunction in a canine model of insulin resistance and moderate obesity. Diabetologia 2016; 59:197-207. [PMID: 26376797 PMCID: PMC5310691 DOI: 10.1007/s00125-015-3767-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/26/2015] [Indexed: 12/30/2022]
Abstract
AIMS/HYPOTHESIS The worldwide incidence of obesity and diabetes continues to rise at an alarming rate. A major cause of the morbidity and mortality associated with obesity and diabetes is heart disease, yet the mechanisms that lead to cardiovascular complications remain unclear. METHODS We performed cardiac MRI to assess left ventricular morphology and function during the development of moderate obesity and insulin resistance in a well-established canine model (n = 26). To assess the influence of dietary fat composition, we randomised animals to a traditional lard diet (rich in saturated and monounsaturated fat; n = 12), a salmon oil diet (rich in polyunsaturated fat; n = 8) or a control diet (n = 6). RESULTS High-fat feeding with lard increased body weight and fasting insulin and markedly reduced insulin sensitivity. Lard feeding also significantly reduced left ventricular function, evidenced by a worsening of circumferential strain and impairment in left ventricular torsion. High-fat feeding with salmon oil increased body weight; however, salmon oil feeding did not impair insulin sensitivity or cardiac function. CONCLUSIONS/INTERPRETATION These data emphasise the importance of dietary fat composition on both metabolic and cardiac function, and have important implications for the relationship between diet and health.
Collapse
Affiliation(s)
- Josiane L Broussard
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Michael D Nelson
- Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Isaac Asare Bediako
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Rebecca L Paszkiewicz
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Laura Smith
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Edward W Szczepaniak
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Darko Stefanovski
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA
| | - Lidia S Szczepaniak
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA.
| |
Collapse
|
16
|
Broussard JL, Kolka CM, Castro AVB, Asare Bediako I, Paszkiewicz RL, Szczepaniak EW, Szczepaniak LS, Knutson KL, Kim SP, Bergman RN. Elevated nocturnal NEFA are an early signal for hyperinsulinaemic compensation during diet-induced insulin resistance in dogs. Diabetologia 2015; 58:2663-70. [PMID: 26254577 PMCID: PMC4591216 DOI: 10.1007/s00125-015-3721-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 07/14/2015] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS A normal consequence of increased energy intake and insulin resistance is compensatory hyperinsulinaemia through increased insulin secretion and/or reduced insulin clearance. Failure of compensatory mechanisms plays a central role in the pathogenesis of type 2 diabetes mellitus; consequently, it is critical to identify in vivo signal(s) involved in hyperinsulinaemic compensation. We have previously reported that high-fat feeding leads to an increase in nocturnal NEFA concentration. We therefore designed this study to test the hypothesis that elevated nocturnal NEFA are an early signal for hyperinsulinaemic compensation for insulin resistance. METHODS Blood sampling was conducted in male dogs to determine 24 h profiles of NEFA at baseline and during high-fat feeding with and without acute nocturnal NEFA suppression using a partial A1 adenosine receptor agonist. RESULTS High-fat feeding increased nocturnal NEFA and reduced insulin sensitivity, effects countered by an increase in acute insulin response to glucose (AIR(g)). Pharmacological NEFA inhibition after 8 weeks of high-fat feeding lowered NEFA to baseline levels and reduced AIR(g) with no effect on insulin sensitivity. A significant relationship emerged between nocturnal NEFA levels and AIR(g). This relationship indicates that the hyperinsulinaemic compensation induced in response to high-fat feeding was prevented when the nocturnal NEFA pattern was returned to baseline. CONCLUSIONS/INTERPRETATION Elevated nocturnal NEFA are an important signal for hyperinsulinaemic compensation during diet-induced insulin resistance.
Collapse
Affiliation(s)
- Josiane L Broussard
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA.
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Ana V B Castro
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Isaac Asare Bediako
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Rebecca L Paszkiewicz
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Edward W Szczepaniak
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Lidia S Szczepaniak
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | | | - Stella P Kim
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, 8700 Beverly Blvd, Los Angeles, CA, 90048, USA
| |
Collapse
|
17
|
Kabir M, Iyer MS, Richey JM, Woolcott OO, Asare Bediako I, Wu Q, Kim SP, Stefanovski D, Kolka CM, Hsu IR, Catalano KJ, Chiu JD, Ionut V, Bergman RN. CB1R antagonist increases hepatic insulin clearance in fat-fed dogs likely via upregulation of liver adiponectin receptors. Am J Physiol Endocrinol Metab 2015; 309:E747-58. [PMID: 26306598 PMCID: PMC4609878 DOI: 10.1152/ajpendo.00196.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/18/2015] [Indexed: 02/06/2023]
Abstract
The improvement of hepatic insulin sensitivity by the cannabinoid receptor 1 (CB1R) antagonist rimonabant (RIM) has been recently been reported to be due to upregulation of adiponectin. Several studies demonstrated that improvement in insulin clearance accompanies the enhancement of hepatic insulin sensitivity. However, the effects of RIM on hepatic insulin clearance (HIC) have not been fully explored. The aim of this study was to explore the molecular mechanism(s) by which RIM affects HIC, specifically to determine whether upregulation of liver adiponectin receptors (ADRs) and other key genes regulated by adiponectin mediate the effects. To induce insulin resistance in skeletal muscle and liver, dogs were fed a hypercaloric high-fat diet (HFD) for 6 wk. Thereafter, while still maintained on a HFD, animals received RIM (HFD+RIM; n = 11) or placebo (HFD+PL; n = 9) for an additional 16 wk. HIC, calculated as the metabolic clearance rate (MCR), was estimated from the euglycemic-hyperinsulinemic clamp. The HFD+PL group showed a decrease in MCR; in contrast, the HFD+RIM group increased MCR. Consistently, the expression of genes involved in HIC, CEACAM-1 and IDE, as well as gene expression of liver ADRs, were increased in the HFD+RIM group, but not in the HFD+PL group. We also found a positive correlation between CEACAM-1 and the insulin-degrading enzyme IDE with ADRs. Interestingly, expression of liver genes regulated by adiponectin and involved in lipid oxidation were increased in the HFD+RIM group. We conclude that in fat-fed dogs RIM enhances HIC, which appears to be linked to an upregulation of the adiponectin pathway.
Collapse
MESH Headings
- Animals
- Antigens, CD/drug effects
- Antigens, CD/metabolism
- Cannabinoid Receptor Antagonists/pharmacology
- Cell Adhesion Molecules/drug effects
- Cell Adhesion Molecules/metabolism
- Diet, High-Fat
- Dogs
- Glucose Clamp Technique
- Insulin/metabolism
- Insulin Resistance
- Insulysin/drug effects
- Insulysin/metabolism
- Liver/drug effects
- Liver/metabolism
- Male
- Metabolic Clearance Rate
- Piperidines/pharmacology
- Pyrazoles/pharmacology
- RNA, Messenger/drug effects
- RNA, Messenger/metabolism
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptors, Adiponectin/drug effects
- Receptors, Adiponectin/genetics
- Receptors, Adiponectin/metabolism
- Rimonabant
- Up-Regulation/drug effects
Collapse
Affiliation(s)
- Morvarid Kabir
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Malini S Iyer
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Joyce M Richey
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Orison O Woolcott
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Isaac Asare Bediako
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Qiang Wu
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Stella P Kim
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Darko Stefanovski
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Cathryn M Kolka
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Isabel R Hsu
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Karyn J Catalano
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Jenny D Chiu
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Viorica Ionut
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| | - Richard N Bergman
- Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, California; and
| |
Collapse
|
18
|
Woolcott OO, Richey JM, Kabir M, Chow RH, Iyer MS, Kirkman EL, Stefanovski D, Lottati M, Kim SP, Harrison LN, Ionut V, Zheng D, Hsu IR, Catalano KJ, Chiu JD, Bradshaw H, Wu Q, Kolka CM, Bergman RN. Corrections: High-Fat Diet-Induced Insulin Resistance does not Increase Plasma Anandamide Levels or Potentiate Anandamide Insulinotropic Effect in Isolated Canine Islets. PLoS One 2015; 10:e0131033. [PMID: 26075612 PMCID: PMC4468268 DOI: 10.1371/journal.pone.0131033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
|
19
|
Kolka CM, Richey JM, Castro AVB, Broussard JL, Ionut V, Bergman RN. Lipid-induced insulin resistance does not impair insulin access to skeletal muscle. Am J Physiol Endocrinol Metab 2015; 308:E1001-9. [PMID: 25852002 PMCID: PMC4451289 DOI: 10.1152/ajpendo.00015.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/03/2015] [Indexed: 11/22/2022]
Abstract
Elevated plasma free fatty acids (FFA) induce insulin resistance in skeletal muscle. Previously, we have shown that experimental insulin resistance induced by lipid infusion prevents the dispersion of insulin through the muscle, and we hypothesized that this would lead to an impairment of insulin moving from the plasma to the muscle interstitium. Thus, we infused lipid into our anesthetized canine model and measured the appearance of insulin in the lymph as a means to sample muscle interstitium under hyperinsulinemic euglycemic clamp conditions. Although lipid infusion lowered the glucose infusion rate and induced both peripheral and hepatic insulin resistance, we were unable to detect an impairment of insulin access to the lymph. Interestingly, despite a significant, 10-fold increase in plasma FFA, we detected little to no increase in free fatty acids or triglycerides in the lymph after lipid infusion. Thus, we conclude that experimental insulin resistance induced by lipid infusion does not reduce insulin access to skeletal muscle under clamp conditions. This would suggest that the peripheral insulin resistance is likely due to reduced cellular sensitivity to insulin in this model, and yet we did not detect a change in the tissue microenvironment that could contribute to cellular insulin resistance.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Joyce M Richey
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Ana Valeria B Castro
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Josiane L Broussard
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Viorica Ionut
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Richard N Bergman
- Department of Physiology and Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, California
| |
Collapse
|
20
|
Castro AVB, Kolka CM, Kim SP, Bergman RN. Obesity, insulin resistance and comorbidities? Mechanisms of association. ACTA ACUST UNITED AC 2015; 58:600-9. [PMID: 25211442 DOI: 10.1590/0004-2730000003223] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 03/30/2014] [Indexed: 12/25/2022]
Abstract
Overall excess of fat, usually defined by the body mass index, is associated with metabolic (e.g. glucose intolerance, type 2 diabetes mellitus (T2DM), dyslipidemia) and non-metabolic disorders (e.g. neoplasias, polycystic ovary syndrome, non-alcoholic fat liver disease, glomerulopathy, bone fragility etc.). However, more than its total amount, the distribution of adipose tissue throughout the body is a better predictor of the risk to the development of those disorders. Fat accumulation in the abdominal area and in non-adipose tissue (ectopic fat), for example, is associated with increased risk to develop metabolic and non-metabolic derangements. On the other hand, observations suggest that individuals who present peripheral adiposity, characterized by large hip and thigh circumferences, have better glucose tolerance, reduced incidence of T2DM and of metabolic syndrome. Insulin resistance (IR) is one of the main culprits in the association between obesity, particularly visceral, and metabolic as well as non-metabolic diseases. In this review we will highlight the current pathophysiological and molecular mechanisms possibly involved in the link between increased VAT, ectopic fat, IR and comorbidities. We will also provide some insights in the identification of these abnormalities.
Collapse
Affiliation(s)
- Ana Valeria B Castro
- Divisão de Endocrinologia e Metabolismo, Departamento de Clínica Médica, FMRP-USP, Ribeirão Preto, SP, Brazil
| | - Cathryn M Kolka
- Diabetes and Obesity Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Stella P Kim
- Diabetes and Obesity Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| | - Richard N Bergman
- Diabetes and Obesity Research Institute, Cedars Sinai Medical Center, Los Angeles, CA, USA
| |
Collapse
|
21
|
Kolka CM, Castro AVB, Kirkman EL, Bergman RN. Modest hyperglycemia prevents interstitial dispersion of insulin in skeletal muscle. Metabolism 2015; 64:330-7. [PMID: 25468139 PMCID: PMC4277905 DOI: 10.1016/j.metabol.2014.10.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/22/2014] [Accepted: 10/28/2014] [Indexed: 10/24/2022]
Abstract
UNLABELLED Insulin injected directly into skeletal muscle diffuses rapidly through the interstitial space to cause glucose uptake, but this is blocked in insulin resistance. As glucotoxicity is associated with endothelial dysfunction, the observed hyperglycemia in diet-induced obese dogs may inhibit insulin access to muscle cells, and exacerbate insulin resistance. Here we asked whether interstitial insulin diffusion is reduced in modest hyperglycemia, similar to that induced by a high fat diet. METHODS During normoglycemic (100 mg/dl) and moderately hyperglycemic (120 mg/dl) clamps in anesthetized canines, sequential doses of insulin were injected into the vastus medialis of one hindlimb; the contra-lateral limb served as a control. Plasma samples were collected and analyzed for insulin content. Lymph vessels of the hind leg were also catheterized, and lymph samples were analyzed as an indicator of interstitial insulin concentration. RESULTS Insulin injection increased lymph insulin in normoglycemic animals, but not in hyperglycemic animals. Muscle glucose uptake was elevated in response to hyperglycemia, however the insulin-mediated glucose uptake in normoglycemic controls was not observed in hyperglycemia. Modest hyperglycemia prevented intra-muscularly injected insulin from diffusing through the interstitial space reduced insulin-mediated glucose uptake. CONCLUSION Hyperglycemia prevents the appearance of injected insulin in the interstitial space, thus reducing insulin action on skeletal muscle cells.
Collapse
MESH Headings
- Absorption, Physiological
- Animals
- Biological Transport/drug effects
- Diffusion
- Dogs
- Dose-Response Relationship, Drug
- Extracellular Space/chemistry
- Glucose/metabolism
- Glucose Clamp Technique
- Hindlimb
- Hyperglycemia/blood
- Hyperglycemia/drug therapy
- Hyperglycemia/metabolism
- Hyperglycemia/physiopathology
- Hypoglycemic Agents/administration & dosage
- Hypoglycemic Agents/metabolism
- Hypoglycemic Agents/pharmacokinetics
- Hypoglycemic Agents/therapeutic use
- Injections, Intramuscular
- Insulin Resistance
- Insulin, Regular, Pork/administration & dosage
- Insulin, Regular, Pork/analysis
- Insulin, Regular, Pork/pharmacokinetics
- Insulin, Regular, Pork/therapeutic use
- Lymph/chemistry
- Lymph/drug effects
- Male
- Quadriceps Muscle/chemistry
- Quadriceps Muscle/drug effects
- Quadriceps Muscle/metabolism
- Severity of Illness Index
- Tissue Distribution
Collapse
Affiliation(s)
- Cathryn M Kolka
- Department of Physiology and Biophysics, University of Southern California, Los Angeles, CA.
| | - Ana Valeria B Castro
- Department of Physiology and Biophysics, University of Southern California, Los Angeles, CA
| | - Erlinda L Kirkman
- Department of Physiology and Biophysics, University of Southern California, Los Angeles, CA
| | - Richard N Bergman
- Department of Physiology and Biophysics, University of Southern California, Los Angeles, CA
| |
Collapse
|
22
|
Castro AV, Woolcott OO, Iyer MS, Kabir M, Ionut V, Stefanovski D, Kolka CM, Szczepaniak LS, Szczepaniak EW, Asare-Bediako I, Paszkiewicz RL, Broussard JL, Kim SP, Kirkman EL, Rios HC, Mkrtchyan H, Wu Q, Ader M, Bergman RN. Increase in visceral fat per se does not induce insulin resistance in the canine model. Obesity (Silver Spring) 2015; 23:105-11. [PMID: 25322680 PMCID: PMC4276477 DOI: 10.1002/oby.20906] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 08/30/2014] [Indexed: 12/25/2022]
Abstract
OBJECTIVES To determine whether a selective increase of visceral adipose tissue content will result in insulin resistance. METHODS Sympathetic denervation of the omental fat was performed under general inhalant anesthesia by injecting 6-hydroxydopamine in the omental fat of lean mongrel dogs (n = 11). In the conscious animal, whole-body insulin sensitivity was assessed by the minimal model (SI ) and the euglycemic hyperinsulinemic clamp (SICLAMP ). Changes in abdominal fat were monitored by magnetic resonance. All assessments were determined before (Wk0) and 2 weeks (Wk2) after denervation. Data are medians (upper and lower interquartile). RESULTS Denervation of omental fat resulted in increased percentage (and content) of visceral fat [Wk0: 10.2% (8.5-11.4); Wk2: 12.4% (10.4-13.6); P < 0.01]. Abdominal subcutaneous fat remained unchanged. However, no changes were found in SI [Wk0: 4.7 (mU/l)(-1) min(-1) (3.1-8.8); Wk2: 5.3 (mU/l)(-1) min(-1) (4.5-7.2); P = 0.59] or SICLAMP [Wk0: 42.0 × 10(-4) dl kg(-1) min(-1) (mU/l)(-1) (41.0-51.0); Wk2: 40.0 × 10(-4) dl kg(-1) min(-1) (mU/l) (-1) (34.0-52.0); P = 0.67]. CONCLUSIONS Despite a selective increase in visceral adiposity in dogs, insulin sensitivity in vivo did not change, which argues against the concept that accumulation of visceral adipose tissue contributes to insulin resistance.
Collapse
Affiliation(s)
- Ana V.B. Castro
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Orison O. Woolcott
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Malini S. Iyer
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Morvarid Kabir
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Viorica Ionut
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Darko Stefanovski
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Cathryn M. Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Lidia S. Szczepaniak
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Edward W. Szczepaniak
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Isaac Asare-Bediako
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | | | - Josiane L. Broussard
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Stella P. Kim
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Erlinda L. Kirkman
- Department of Animal Resources, University of Southern California, Los Angeles
| | - Hernan C. Rios
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Hasmik Mkrtchyan
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Qiang Wu
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Marilyn Ader
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| | - Richard N. Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles
| |
Collapse
|
23
|
Ionut V, Castro AVB, Woolcott OO, Stefanovski D, Iyer MS, Broussard JL, Burch M, Elazary R, Kolka CM, Mkrtchyan H, Bediako IA, Bergman RN. Hepatic portal vein denervation impairs oral glucose tolerance but not exenatide's effect on glycemia. Am J Physiol Endocrinol Metab 2014; 307:E644-52. [PMID: 25117408 PMCID: PMC4200304 DOI: 10.1152/ajpendo.00244.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The hepatoportal area is an important glucohomeostatic metabolic sensor, sensing hypoglycemia, hyperglycemia, and hormones such as glucagon-like peptide-1 (GLP-1). We have reported previously that activation of hepatoportal sensors by intraportal infusion of glucose and GLP-1 or by subcutaneous administration of GLP-1 receptor activator exenatide and of intraportal glucose improved glycemia independent of corresponding changes in pancreatic hormones. It is not clear whether this effect is mediated via the portal vein (PV) or by direct action on the liver itself. To test whether receptors in the PV mediate exenatide's beneficial effect on glucose tolerance, we performed 1) paired oral glucose tolerance tests (OGTT) with and without exenatide and 2) intravenous glucose tolerance tests before and after PV denervation in canines. Denervation of the portal vein affected oral glucose tolerance; post-denervation (POST-DEN) OGTT glucose and insulin AUC were 50% higher than before denervation (P = 0.01). However, portal denervation did not impair exenatide's effect to improve oral glucose tolerance (exenatide effect: 48 ± 12 mmol·l⁻¹·min before vs. 64 ± 26 mmol·l⁻¹·min after, P = 0.67). There were no changes in insulin sensitivity or secretion during IVGTTs. Portal vein sensing might play a role in controlling oral glucose tolerance during physiological conditions but not in pharmacological activation of GLP-1 receptors by exenatide.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Miguel Burch
- Department of Surgery, Cedars Sinai Medical Center, Los Angeles, California
| | - Ram Elazary
- Department of Surgery, Cedars Sinai Medical Center, Los Angeles, California
| | | | | | | | | |
Collapse
|
24
|
Ader M, Stefanovski D, Richey JM, Kim SP, Kolka CM, Ionut V, Kabir M, Bergman RN. Failure of homeostatic model assessment of insulin resistance to detect marked diet-induced insulin resistance in dogs. Diabetes 2014; 63:1914-9. [PMID: 24353184 PMCID: PMC4876683 DOI: 10.2337/db13-1215] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Accurate quantification of insulin resistance is essential for determining efficacy of treatments to reduce diabetes risk. Gold-standard methods to assess resistance are available (e.g., hyperinsulinemic clamp or minimal model), but surrogate indices based solely on fasting values have attractive simplicity. One such surrogate, the homeostatic model assessment of insulin resistance (HOMA-IR), is widely applied despite known inaccuracies in characterizing resistance across groups. Of greater significance is whether HOMA-IR can detect changes in insulin sensitivity induced by an intervention. We tested the ability of HOMA-IR to detect high-fat diet-induced insulin resistance in 36 healthy canines using clamp and minimal model analysis of the intravenous glucose tolerance test (IVGTT) to document progression of resistance. The influence of pancreatic function on HOMA-IR accuracy was assessed using the acute insulin response during the IVGTT (AIRG). Diet-induced resistance was confirmed by both clamp and minimal model (P < 0.0001), and measures were correlated with each other (P = 0.001). In striking contrast, HOMA-IR ([fasting insulin (μU/mL) × fasting glucose (mmol)]/22.5) did not detect reduced sensitivity induced by fat feeding (P = 0.22). In fact, 13 of 36 animals showed an artifactual decrease in HOMA-IR (i.e., increased sensitivity). The ability of HOMA-IR to detect diet-induced resistance was particularly limited under conditions when insulin secretory function (AIRG) is less than robust. In conclusion, HOMA-IR is of limited utility for detecting diet-induced deterioration of insulin sensitivity quantified by glucose clamp or minimal model. Caution should be exercised when using HOMA-IR to detect insulin resistance when pancreatic function is compromised. It is necessary to use other accurate indices to detect longitudinal changes in insulin resistance with any confidence.
Collapse
Affiliation(s)
- Marilyn Ader
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Darko Stefanovski
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Joyce M. Richey
- Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Stella P. Kim
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Cathryn M. Kolka
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Viorica Ionut
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Morvarid Kabir
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| | - Richard N. Bergman
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA
| |
Collapse
|
25
|
Ader M, Stefanovski D, Kim SP, Richey JM, Ionut V, Catalano KJ, Hucking K, Ellmerer M, Van Citters G, Hsu IR, Chiu JD, Woolcott OO, Harrison LN, Zheng D, Lottati M, Kolka CM, Mooradian V, Dittmann J, Yae S, Liu H, Castro AVB, Kabir M, Bergman RN. Hepatic insulin clearance is the primary determinant of insulin sensitivity in the normal dog. Obesity (Silver Spring) 2014; 22:1238-45. [PMID: 24123967 PMCID: PMC3969862 DOI: 10.1002/oby.20625] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 08/15/2013] [Accepted: 09/10/2013] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Insulin resistance is a powerful risk factor for Type 2 diabetes and a constellation of chronic diseases, and is most commonly associated with obesity. We examined if factors other than obesity are more substantial predictors of insulin sensitivity under baseline, nonstimulated conditions. METHODS Metabolic assessment was performed in healthy dogs (n = 90). Whole-body sensitivity from euglycemic clamps (SICLAMP ) was the primary outcome variable, and was measured independently by IVGTT (n = 36). Adiposity was measured by MRI (n = 90), and glucose-stimulated insulin response was measured from hyperglycemic clamp or IVGTT (n = 86 and 36, respectively). RESULTS SICLAMP was highly variable (5.9-75.9 dl/min per kg per μU/ml). Despite narrow range of body weight (mean, 28.7 ± 0.3 kg), adiposity varied approximately eight-fold and was inversely correlated with SICLAMP (P < 0.025). SICLAMP was negatively associated with fasting insulin, but most strongly associated with insulin clearance. Clearance was the dominant factor associated with sensitivity (r = 0.53, P < 0.00001), whether calculated from clamp or IVGTT. CONCLUSIONS These data suggest that insulin clearance contributes substantially to insulin sensitivity, and may be pivotal in understanding the pathogenesis of insulin resistance. We propose the hyperinsulinemia due to reduction in insulin clearance is responsible for insulin resistance secondary to changes in body weight.
Collapse
Affiliation(s)
- Marilyn Ader
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
The vascular endothelium has been identified as an important component in diabetes-associated complications, which include many cardiovascular disorders such as atherosclerosis, hypertension and peripheral neuropathy. Additionally, insulin's actions on the endothelium are now seen as a major factor in the metabolic effects of the hormone by increasing access to insulin sensitive tissues. Endothelial function is impaired in diabetes, obesity, and the metabolic syndrome, which could reduce insulin access to the tissue, and thus reduce insulin sensitivity independently of direct effects at the muscle cell. As such, the endothelium is a valid target for treatment of both the impaired glucose metabolism in diabetes, as well as the vascular based complications of diabetes. Here we review the basics of the endothelium in insulin action, with a focus on the skeletal muscle as insulin's major metabolic organ, and how this is affected by diabetes. We will focus on the most recent developments in the field, including current treatment possibilities.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA.
| | | |
Collapse
|
27
|
Abstract
Hormones are involved in a plethora of processes including development and growth, metabolism, mood, and immune responses. These essential functions are dependent on the ability of the hormone to access its target tissue. In the case of endocrine hormones that are transported through the blood, this often means that the endothelium must be crossed. Many studies have shown that the concentrations of hormones and nutrients in blood can be very different from those surrounding the cells on the tissue side of the blood vessel endothelium, suggesting that transport across this barrier can be rate limiting for hormone action. This transport can be regulated by altering the surface area of the blood vessel available for diffusion through to the underlying tissue or by the permeability of the endothelium. Many hormones are known to directly or indirectly affect the endothelial barrier, thus affecting their own distribution to their target tissues. Dysfunction of the endothelial barrier is found in many diseases, particularly those associated with the metabolic syndrome. The interrelatedness of hormones may help to explain why the cluster of diseases in the metabolic syndrome occur together so frequently and suggests that treating the endothelium may ameliorate defects in more than one disease. Here, we review the structure and function of the endothelium, its contribution to the function of hormones, and its involvement in disease.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Diabetes and Obesity Research Institute, Department of Biomedical Science, Cedars-Sinai Medical Center, Los Angeles, California, USA.
| | | |
Collapse
|
28
|
Abstract
Recent studies have shown that adiponectin is able to increase nitric oxide (NO) production by the endothelium and relax preconstricted isolated aortic rings, suggesting that adiponectin may act as a vasodilator. Endothelin-1 (ET-1) is a potent vasoconstrictor, elevated levels of which are associated with obesity, type 2 diabetes, hypertension, and cardiovascular disease. We hypothesized that adiponectin has NO-dependent vascular actions opposing the vasoconstrictor actions of ET-1. We studied the vascular and metabolic effects of a physiological concentration of adiponectin (6.5 μg/ml) on hooded Wistar rats in the constant-flow pump-perfused rat hindlimb. Adiponectin alone had no observable vascular activity; however, adiponectin pretreatment and coinfusion inhibited the increase in perfusion pressure and associated metabolic stimulation caused by low-dose (1 nM) ET-1. Adiponectin was not able to oppose vasoconstriction when infusion was commenced after ET-1. This is in contrast to the NO donor sodium nitroprusside, which significantly reduced the pressure due to established ET-1 vasoconstriction, suggesting dissociation of the actions of adiponectin and NO. In addition, adiponectin had no effect on vasoconstriction caused by either high-dose (20 nM) ET-1 or low-dose (50 nM) norepinephrine. Our findings suggest that adiponectin has specific, apparently NO-independent, vascular activity to oppose the vasoconstrictor effects of ET-1. The hemodynamic actions of adiponectin may be an important aspect of its insulin-sensitizing ability by regulating access of insulin and glucose to myocytes. Imbalance in the relationship between adiponectin and ET-1 in obesity may contribute to the development of insulin resistance and cardiovascular disease.
Collapse
Affiliation(s)
- Carol T Bussey
- Menzies Research Institute, Medical Science 1 Bldg., Private Bag 23, Hobart, Tasmania, Australia 7000
| | | | | | | |
Collapse
|
29
|
Abstract
OBJECTIVE Obesity causes insulin resistance, which has been interpreted as reduced downstream insulin signaling. However, changes in access of insulin to sensitive tissues such as skeletal muscle may also play a role. Insulin injected directly into skeletal muscle diffuses rapidly through the interstitial space to cause glucose uptake. When insulin resistance is induced by exogenous lipid infusion, this interstitial diffusion process is curtailed. Thus, the possibility exists that hyperlipidemia, such as that seen during obesity, may inhibit insulin action to muscle cells and exacerbate insulin resistance. Here we asked whether interstitial insulin diffusion is reduced in physiological obesity induced by a high-fat diet (HFD). RESEARCH DESIGN AND METHODS Dogs were fed a regular diet (lean) or one supplemented with bacon grease for 9-12 weeks (HFD). Basal insulin (0.2 mU x min(-1) x kg(-1)) euglycemic clamps were performed on fat-fed animals (n = 6). During clamps performed under anesthesia, five sequential doses of insulin were injected into the vastus medialis of one hind limb (INJ); the contralateral limb (NINJ) served as a control. RESULTS INJ lymph insulin showed an increase above NINJ in lean animals, but no change in HFD-fed animals. Muscle glucose uptake observed in lean animals did not occur in HFD-fed animals. CONCLUSIONS Insulin resistance induced by HFD caused a failure of intramuscularly injected insulin to diffuse through the interstitial space and failure to cause glucose uptake, compared with normal animals. High-fat feeding prevents the appearance of injected insulin in the interstitial space, thus reducing binding to skeletal muscle cells and glucose uptake.
Collapse
Affiliation(s)
- Cathryn M. Kolka
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
| | - L. Nicole Harrison
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
| | - Maya Lottati
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
| | - Jenny D. Chiu
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
| | - Erlinda L. Kirkman
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
| | - Richard N. Bergman
- From the Department of Physiology and Biophysics, University of Southern California, Los Angeles, California
- Corresponding author: Richard N. Bergman,
| |
Collapse
|
30
|
Chiu JD, Kolka CM, Richey JM, Harrison LN, Zuniga E, Kirkman EL, Bergman RN. Experimental hyperlipidemia dramatically reduces access of insulin to canine skeletal muscle. Obesity (Silver Spring) 2009; 17:1486-92. [PMID: 19521354 PMCID: PMC3417110 DOI: 10.1038/oby.2009.165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A complex sequence of steps is required for insulin to cause glucose uptake. Impairment of any one of these steps can contribute to insulin resistance. We observed the effect of insulin resistance induced by hyperlipidemia on the dynamics of insulin injected into skeletal muscle. Basal insulin euglycemic clamps (0.2 mU/min/kg) with or without lipid infusions (20% at 1.5 ml/min) were done on anesthetized dogs. Sequential insulin doses were administered by intramuscular injection directly into the vastus medialis of one hindlimb, using the contralateral leg for comparison. Intramuscular insulin injection in normal animals caused a clear dose-dependent increment in interstitial insulin levels, as well as dose-dependent increase in leg glucose uptake. In a second group of animals, lipid was infused before and during intramuscular insulin injection to cause systemic increase in free fatty acids (FFAs). In sharp contrast, systemic lipid infusion caused insulin resistance, indicated by reduced glucose infusion required to maintain euglycemia, and prevented injection-induced increase in lymphatic insulin and leg glucose uptake observed without lipid. The injected insulin was instead detected in the venous outflow from the leg. Lipid infusion caused intramuscular insulin to be diverted from interstitium into the capillary circulation, preventing a rise in interstitial insulin and any increase in local leg glucose uptake. The diversion of insulin from the interstitium under hyperlipidemic conditions may play a role in the insulin resistance observed coincident with elevated nocturnal FFAs as is observed in obesity.
Collapse
Affiliation(s)
- Jenny D Chiu
- Department of Physiology and Biophysics, University of Southern California, Los Angeles, California, USA
| | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
Visceral adiposity is strongly associated with insulin resistance; however, little evidence directly demonstrates that visceral fat per se impairs insulin action. Here, we examine the effects of the surgical removal of the greater omentum and its occupying visceral fat, an omentectomy (OM), on insulin sensitivity (S(I)) and beta-cell function in nonobese dogs. Thirteen male mongrel dogs were used in this research study; animals were randomly assigned to surgical treatment with either OM (n = 7), or sham-surgery (SHAM) (n = 6). OM failed to generate measurable changes in body weight (+2%; P = 0.1), or subcutaneous adiposity (+3%; P = 0.83) as assessed by magnetic resonance imaging (MRI). The removal of the greater omentum did not significantly reduce total visceral adipose volume (-7.3 +/- 6.4%; P = 0.29); although primary analysis showed a trend for OM to increase S(I) when compared to sham operated animals (P = 0.078), further statistical analysis revealed that this minor reduction in visceral fat alleviated insulin resistance by augmenting S(I) of the periphery (+67.7 +/- 35.2%; P = 0.03), as determined by the euglycemic-hyperinsulinemic clamp. Insulin secretory response during the hyperglycemic step clamp was not directly influenced by omental fat removal (presurgery 6.82 +/- 1.4 vs. postsurgery: 6.7 +/- 1.2 pmol/l/mg/dl, P = 0.9). These findings provide new evidence for the deleterious role of visceral fat in insulin resistance, and suggest that a greater OM procedure may effectively improve insulin sensitivity.
Collapse
Affiliation(s)
- Maya Lottati
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, California, USA
| | | | | | | | | |
Collapse
|
32
|
Chiu JD, Richey JM, Harrison LN, Zuniga E, Kolka CM, Kirkman E, Ellmerer M, Bergman RN. Direct administration of insulin into skeletal muscle reveals that the transport of insulin across the capillary endothelium limits the time course of insulin to activate glucose disposal. Diabetes 2008; 57:828-35. [PMID: 18223011 DOI: 10.2337/db07-1444] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Intravenous insulin infusion rapidly increases plasma insulin, yet glucose disposal occurs at a much slower rate. This delay in insulin's action may be related to the protracted time for insulin to traverse the capillary endothelium. An increased delay may be associated with the development of insulin resistance. The purpose of the present study was to investigate whether bypassing the transendothelial insulin transport step and injecting insulin directly into the interstitial space would moderate the delay in glucose uptake observed with intravenous administration of the hormone. RESEARCH DESIGN AND METHODS Intramuscular injections of saline (n = 3) or insulin (n = 10) were administered directly into the vastus medialis of anesthetized dogs. Injections of 0.3, 0.5, 0.7, 1.0, and 3.0 units insulin were administered hourly during a basal insulin euglycemic glucose clamp (0.2mU x min(-1) x kg(-1)). RESULTS Unlike the saline group, each incremental insulin injection caused interstitial (lymph) insulin to rise within 10 min, indicating rapid diffusion of the hormone within the interstitial matrix. Delay in insulin action was virtually eliminated, indicated by immediate dose-dependent increments in hindlimb glucose uptake. Additionally, bypassing insulin transport by direct injection into muscle revealed a fourfold greater sensitivity to insulin of in vivo muscle tissue than previously reported from intravenous insulin administration. CONCLUSIONS Our results indicate that the transport of insulin to skeletal muscle is a rate-limiting step for insulin to activate glucose disposal. Based on these results, we speculate that defects in insulin transport across the endothelial layer of skeletal muscle will contribute to insulin resistance.
Collapse
Affiliation(s)
- Jenny D Chiu
- Department of Physiology and Biophysics, University of Southern California, Keck School of Medicine, 1333 San Pablo St., MMR 626, Los Angeles, CA 90033, USA
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
1. The present study examined the potential for reduced exercise capacity observed in hypertensive patients as a result of elevated levels of endothelin (ET)-1. We have previously reported that ET-1 exerts low-dose stimulatory or high-dose inhibitory effects on the metabolism of the rat isolated perfused hindlimb from its vasoconstrictor activity. 2. Herein, we determined whether there are similar effects on tension development by the rat isolated constant-flow hindlimb during ET-1-mediated vasoconstriction. 3. The dose-dependent vasoconstrictor effects of ET-1 on metabolism in contracting muscle were the same as those observed previously in resting muscle. Highest concentrations of ET-1 gave rise to a transient stimulation followed by a marked inhibition of tension development, consistent with a decrease in aerobic capacity of the muscle. The vasoconstriction due to the higher doses of ET-1 was not dilated by electrical stimulation. 4. In conclusion, the biphasic nature of the actions of ET-1 suggests that although lower concentrations of ET-1 do not affect exercise capacity, higher concentrations that may occur in hypertension are inhibitory to metabolism and aerobic capacity of muscle. The inhibitory effects of ET-1 appear to result from enhanced functional shunting.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Biochemistry, Medical School, University of Tasmania, Hobart, Tasmania, Australia.
| | | | | | | |
Collapse
|
34
|
Abstract
AIMS/HYPOTHESIS Plasma levels of endothelin-1 are frequently elevated in patients with hypertension, obesity and type 2 diabetes. We hypothesise that this vasoconstrictor may prevent full perfusion of muscle, thereby limiting delivery of insulin and glucose and contributing to insulin resistance. MATERIALS AND METHODS The acute effects of endothelin-1 on insulin-mediated haemodynamic and metabolic effects were examined in rats in vivo. Endothelin-1 (50 pmol min(-1) kg(-1) for 2.5 h) was infused alone, or 30 min prior to a hyperinsulinaemic-euglycaemic insulin clamp (10 mU min(-1) kg(-1) for 2 h). Insulin clamps (10 or 15 mU min(-1) kg(-1)) were performed after 30 min of saline infusion. RESULTS Endothelin-1 infusion alone increased plasma endothelin-1 11-fold (p < 0.05) and blood pressure by 20% (p < 0.05). Endothelin-1 alone had no effect on femoral blood flow, capillary recruitment or glucose uptake, but endothelin-1 with 10 mU min(-1) kg(-1) insulin caused a decrease in insulin clearance from 0.35 +/- 0.6 to 0.19 +/- 0.02 ml/min (p = 0.02), resulting in significantly higher plasma insulin levels (10 mU min(-1) kg(-1) insulin: 2,120 +/- 190 pmol/l; endothelin-1 + 10 mU min(-1)kg(-1) insulin: 4,740 +/- 910 pmol/l), equivalent to 15 mU min(-1) kg(-1) insulin alone (4,920 +/- 190 pmol/l). The stimulatory effects of equivalent doses of insulin on femoral blood flow, capillary recruitment and glucose uptake were blocked by endothelin-1. CONCLUSIONS/INTERPRETATION Endothelin-1 blocks insulin's haemodynamic effects, particularly capillary recruitment, and is associated with decreased muscle glucose uptake and glucose infusion rate. These findings suggest that elevated endothelin-1 levels may contribute to insulin resistance of muscle by increasing vascular resistance and limiting insulin and glucose delivery.
Collapse
Affiliation(s)
- R M Ross
- Biochemistry, School of Medicine, University of Tasmania, Private Bag 58, Hobart, 7001, Australia
| | | | | | | |
Collapse
|
35
|
Mahajan H, Kolka CM, Newman JMB, Rattigan S, Richards SM, Clark MG. Vascular and metabolic effects of methacholine in relation to insulin action in muscle. Diabetologia 2006; 49:713-23. [PMID: 16477439 DOI: 10.1007/s00125-005-0110-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [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] [Received: 08/28/2005] [Accepted: 10/18/2005] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS Methacholine (MC) is a nitric oxide vasodilator, but unlike other vasodilators, it potentiates insulin-mediated glucose uptake by muscle. The present study aimed to resolve whether this action was the result of a vascular effect of MC leading to increased muscle perfusion or a direct effect of MC on the myocytes. We hypothesise that vascular-mediated insulin-stimulated glucose uptake responses to MC occur at lower doses than direct myocyte MC-mediated increases in glucose uptake. METHODS The vascular and metabolic effects of this vasodilator were examined in rats in vivo using a novel local infusion technique, and in the pump-perfused rat hindlimb under conditions of constant flow. RESULTS Local infusion of low-dose MC (0.3 micromol/l) into the epigastric artery of one leg (test) in vivo markedly increased femoral blood flow and decreased vascular resistance, without effects in the contra-lateral leg. Capillary recruitment, but not glucose uptake, was increased in the test leg. All increases caused by MC were confined to the test leg and blocked by local infusion into the test leg of N-nitro-L-arginine methyl ester (L-NAME), but not by infusion of N-nitro-D-arginine methyl ester (D-NAME). In the constant-flow pump-perfused rat hindlimb, infusion of 0.6 micromol/l MC vasodilated the pre-constriction effected by 70 nmol/l noradrenaline or 300 nmol/l serotonin, and this was blocked by 10 micromol/l L-NAME. 2-Deoxyglucose in muscle was increased by 30 micromol/l MC (p<0.05), but was unaffected by 3 micromol/l MC. All increases in 2-deoxyglucose uptake by 30 micromol/l MC were blocked by 10 micromol/l L-NAME. CONCLUSIONS/INTERPRETATION MC has dose-dependent effects both on the vasculature and on muscle metabolism. At low dose (0.3-3 micromol/l), MC is a potent vasodilator in muscle, both in vivo and in vitro, without metabolic effects; at higher doses (> or =30 micromol/l) MC has a direct metabolic effect leading to increased glucose uptake. Both the vascular and metabolic effects are sensitive to L-NAME. The low-dose enhancement of insulin action in vivo by MC, which has been reported previously, thus seems to be attributable to vascular effects.
Collapse
Affiliation(s)
- H Mahajan
- Biochemistry, University of Tasmania, 7001, Hobart, TAS, Australia
| | | | | | | | | | | |
Collapse
|
36
|
Abstract
Insulin mediates its own access and that of glucose to muscle by capillary recruitment and an increase in bulk blood flow. In addition, insulin resistance of muscle may result in part from an impaired hemodynamic action of insulin. The present review examines some of the factors that influence the effects of insulin both at the level of hemodynamics and metabolism in muscle. Factors include fatty acids, the inflammatory cytokine TNFalpha, vasodilators that relax the blood vessels and increase bulk flow, and elevated blood pressure that may be mediated by endothelin, a potent locally released vasoconstrictor, or other vasoconstrictor influences.
Collapse
Affiliation(s)
- Stephen Rattigan
- Biochemistry, Medical School, University of Tasmania, Hobart, Australia.
| | | | | | | | | | | |
Collapse
|
37
|
Kolka CM, Rattigan S, Richards S, Clark MG. Metabolic and vascular actions of endothelin-1 are inhibited by insulin-mediated vasodilation in perfused rat hindlimb muscle. Br J Pharmacol 2006; 145:992-1000. [PMID: 15895101 PMCID: PMC1576215 DOI: 10.1038/sj.bjp.0706263] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Endothelin-1 (ET-1) is a potent endothelium-derived vasoactive peptide and may be involved in the microvascular actions of insulin for the normal delivery of nutrients to muscle, although higher levels may be antagonistic. Our aim was to observe the interaction between ET-1 and insulin. Initially, we attempted to distinguish the vascular from the metabolic effects of ET-1 in the constant-flow pump-perfused rat hindlimb by using various doses of ET-1 and measuring changes in perfusion pressure (PP), oxygen consumption (VO(2)), glucose uptake (GU) and lactate release (LR). Sodium nitroprusside (SNP) was used to block vasoconstriction and to thus assess the relationship between vascular and metabolic effects. Insulin was included in later experiments to determine the interaction between insulin and ET-1 on the above parameters. ET-1 caused a dose-dependent increase in PP. Effects on VO(2) were biphasic, with low doses increasing VO(2), and higher doses leading to a net inhibition. GU and LR were increased at lower doses (ET-1 < or =1 nM), but this effect was lost at higher doses (> or =10 nM ET-1). SNP (50 microM) fully blocked the increase in pressure and metabolism due to low-dose ET-1 and partly blocked both pressure and metabolic responses by the high dose. ET-1 vasodilatory activity was minimal at high or low dose. Insulin (15 nM) alone caused GU, which was not affected by ET-1. Of the other parameters measured, insulin behaved essentially the same as SNP, inhibiting the pressure and oxygen effects. Overall, these results show that ET-1 has a biphasic dose-dependent vasoconstrictor effect on hindlimb blood vessels, able to modulate flow to cause both the stimulation and inhibition of metabolism, although these effects are blocked by insulin, which is able to vasodilate against both low and high doses of ET-1.
Collapse
Affiliation(s)
- Cathryn M Kolka
- Department of Biochemistry, Medical School, University of Tasmania, Private Bag 58, Hobart 7001, Australia
| | - Stephen Rattigan
- Department of Biochemistry, Medical School, University of Tasmania, Private Bag 58, Hobart 7001, Australia
| | - Stephen Richards
- Department of Biochemistry, Medical School, University of Tasmania, Private Bag 58, Hobart 7001, Australia
| | - Michael G Clark
- Department of Biochemistry, Medical School, University of Tasmania, Private Bag 58, Hobart 7001, Australia
- Author for correspondence:
| |
Collapse
|
38
|
Abstract
A recent report indicates that the Na+-D-glucose cotransporter SGLT1 is present in capillaries of skeletal muscle and is required for insulin-mediated glucose uptake in myocytes. This result is based on the complete inhibition of insulin-mediated muscle glucose uptake by phlorizin, an inhibitor of SGLT1. Using the pump-perfused rat hind limb, we measured glucose uptake, lactate efflux, and radioactive 2-deoxyglucose uptake into individual muscles with saline (control), phlorizin, insulin, and insulin plus phlorizin, as well as with saline and insulin using normal and low Na+ perfusion buffer. Insulin-mediated glucose uptake was not inhibited after correction for phlorizin interference in the glucose assay. Lactate efflux and 2-deoxyglucose uptake by individual muscles were unaffected by phlorizin. Low Na+ buffer did not affect insulin-mediated glucose uptake, lactate efflux, or 2-deoxyglucose uptake. We conclude that endothelial SGLT1 exerts no barrier for glucose delivery to myocytes.
Collapse
Affiliation(s)
- C M Kolka
- Dept of Biochemistry, Medical School, University of Tasmania, Hobart, Australia.
| | | | | | | | | |
Collapse
|
39
|
Wallis MG, Smith ME, Kolka CM, Zhang L, Richards SM, Rattigan S, Clark MG. Acute glucosamine-induced insulin resistance in muscle in vivo is associated with impaired capillary recruitment. Diabetologia 2005; 48:2131-9. [PMID: 16059714 DOI: 10.1007/s00125-005-1887-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [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] [Received: 01/19/2005] [Accepted: 04/18/2005] [Indexed: 01/04/2023]
Abstract
AIMS/HYPOTHESIS Glucose toxicity and glucosamine-induced insulin resistance have been attributed to products of glucosamine metabolism. In addition, endothelial cell nitric oxide synthase is inhibited by glucosamine. Since insulin has endothelial nitric-oxide-dependent vasodilatory effects in muscle, we hypothesise that glucosamine-induced insulin resistance in muscle in vivo is associated with impaired vascular responses including capillary recruitment. MATERIALS AND METHODS Glucosamine (6.48 mg kg(-1) min(-1) for 3 h) was infused with or without insulin (10 mU kg(-1) min(-1)) into anaesthetised rats under euglycaemic conditions. RESULTS Glucosamine infusion alone increased blood glucosamine (1.9+/-0.1 mmol/l) and glucose (5.4+/-0.2 to 7.7+/-0.3 mmol/l) (p<0.05) but not insulin. Glucosamine induced both hepatic and muscle insulin resistance as evident from measures of glucose appearance and disposal as well as hind-leg glucose uptake, which was inhibited by approx. 50% (p<0.05). Insulin-mediated increases in femoral arterial blood flow and capillary recruitment were completely blocked by glucosamine. CONCLUSION/INTERPRETATION Glucosamine mediates a major impairment of insulin action in muscle vasculature associated with the insulin resistance of muscle. Further studies will be required to assess whether the impaired capillary recruitment contributes to insulin resistance.
Collapse
Affiliation(s)
- M G Wallis
- Biochemistry, School of Medicine, University of Tasmania, Private Bag 58, Hobart, Tasmania 7001, Australia
| | | | | | | | | | | | | |
Collapse
|