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Sanni O, Terre'Blanche G. Dual A 1 and A 2A adenosine receptor antagonists, methoxy substituted 2-benzylidene-1-indanone, suppresses intestinal postprandial glucose and attenuates hyperglycaemia in fructose-streptozotocin diabetic rats. BMC Endocr Disord 2023; 23:97. [PMID: 37143025 PMCID: PMC10157944 DOI: 10.1186/s12902-023-01354-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 04/26/2023] [Indexed: 05/06/2023] Open
Abstract
BACKGROUND/AIM Recent research suggests that adenosine receptors (ARs) influence many of the metabolic abnormalities associated with diabetes. A non-xanthine benzylidene indanone derivative 2-(3,4-dihydroxybenzylidene)-4-methoxy-2,3-dihydro-1 H-inden-1-one (2-BI), has shown to exhibit higher affinity at A1/A2A ARs compared to caffeine. Due to its structural similarity to caffeine, and the established antidiabetic effects of caffeine, the current study was initiated to explore the possible antidiabetic effect of 2-BI. METHODS The study was designed to assess the antidiabetic effects of several A1 and/or A2A AR antagonists, via intestinal glucose absorption and glucose-lowering effects in fructose-streptozotocin (STZ) induced diabetic rats. Six-week-old male Sprague-Dawley rats were induced with diabetes via fructose and streptozotocin. Rats were treated for 4 weeks with AR antagonists, metformin and pioglitazone, respectively. Non-fasting blood glucose (NFBG) was determined weekly and the oral glucose tolerance test (OGTT) was conducted at the end of the intervention period. RESULTS Dual A1/A2A AR antagonists (caffeine and 2-BI) decreased glucose absorption in the intestinal membrane significantly (p < 0.01), while the selective A2A AR antagonist (Istradefylline), showed the highest significant (p < 0.001) reduction in intestinal glucose absorption. The selective A1 antagonist (DPCPX) had the least significant (p < 0.05) reduction in glucose absorption. Similarly, dual A1/A2A AR antagonists and selective A2A AR antagonists significantly reduced non-fast blood glucose and improved glucose tolerance in diabetic rats from the first week of the treatment. Conversely, the selective A1 AR antagonist did not reduce non-fast blood glucose significantly until the 4th week of treatment. 2-BI, caffeine and istradefylline compared well with standard antidiabetic treatments, metformin and pioglitazone, and in some cases performed even better. CONCLUSION 2-BI exhibited good antidiabetic activity by reducing intestinal postprandial glucose absorption and improving glucose tolerance in a diabetic animal model. The dual antagonism of A1/A2A ARs presents a positive synergism that could provide a new possibility for the treatment of diabetes.
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Affiliation(s)
- Olakunle Sanni
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen), School of Health Sciences, North-West University (NWU), Potchefstroom, 2357, South Africa.
| | - Gisella Terre'Blanche
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen), School of Health Sciences, North-West University (NWU), Potchefstroom, 2357, South Africa
- Pharmaceutical Chemistry, School of Pharmacy, North-West University (NWU), Private Bag X6001, Potchefstroom, 2520, South Africa
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Shimada K, Kanasaki K, Kato M, Ogura Y, Takagaki Y, Monno I, Hirai T, Kitada M, Koya D. Adenosine/A1R signaling pathway did not play dominant roles on the influence of SGLT2 inhibitor in the kidney of BSA‐overloaded STZ‐induced diabetic mice. J Diabetes Investig 2022; 13:955-964. [PMID: 35098679 PMCID: PMC9153834 DOI: 10.1111/jdi.13760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/21/2022] [Accepted: 01/26/2022] [Indexed: 11/28/2022] Open
Abstract
Aims/Introduction Sodium–glucose cotransporter 2 inhibitors (SGLT2i) have been shown to display excellent renoprotective effects in diabetic kidney disease with macroalbuminuria/proteinuria. Regarding the renoprotective mechanism of SGLT2i, a sophisticated hypothesis was made by explaining the suppression of glomerular hypertension/hyperfiltration through the adenosine/adenosine type 1 receptor (A1R) signaling‐mediated restoration of the tubuloglomerular feedback mechanism; however, how such A1R signaling is relevant for renoprotection by SGLT2i in diabetic kidney disease with proteinuria has not been elucidated. Materials and Methods Streptozotocin‐induced diabetic CD‐1 mice were injected with bovine serum albumin (BSA) and treated with SGLT2i in the presence/absence of A1R inhibitor administration. Results We found that the influences of SGLT2i are essentially independent of the activation of A1R signaling in the kidney of BSA‐overloaded streptozotocin‐induced diabetic mice. BSA‐overloaded diabetic mice showed the trend of kidney damage with higher glomerular filtration rate (GFR) and the significant induction of fibrogenic genes, such as transforming growth factor‐β2 and collagen type III. SGLT2i TA‐1887 suppressed diabetes‐induced GFR in BSA‐overloaded diabetic mice was associated with the significant suppression of transforming growth factor‐β2 and collagen type III; A1R‐specific inhibitor 8‐cyclopentyl‐1,3‐dipropylxanthine did not cancel the effects of TA‐1887 on either GFR or associated gene levels. Both TA‐1887 and 8‐cyclopentyl‐1,3‐dipropylxanthine‐treated BSA‐overloaded diabetic mice showed suppressed glycated hemoglobin levels associated with the increased food intake. When analyzing the association among histological evaluation, GFR and potential fibrogenic gene levels, each group of mice showed distinct correlation patterns. Conclusions A1R signaling activation was not the dominant mechanism on the influence of SGLT2i in the kidney of BSA‐overloaded diabetic mice.
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Affiliation(s)
- Keiji Shimada
- Department of Diabetology and Endocrinology Kanazawa Medical University
| | - Keizo Kanasaki
- Department of Diabetology and Endocrinology Kanazawa Medical University
- Division of Anticipatory Molecular Food Science and Technology Medical Research Institute Kanazawa Medical University Uchinada, Ishikawa Japan
- Internal Medical 1 Shimane University Faculty of Medicine Izumo, Shimane Japan
| | - Makoto Kato
- Ikuyaku. Integrated Value Development Division Mitsubishi Tanabe Pharma Corporation Tokyo Japan
- Naka Kinen Clinic Ibaraki Japan
- Department of Cardiology International Medical Center Saitama Medical University Saitama Japan
| | - Yoshio Ogura
- Department of Diabetology and Endocrinology Kanazawa Medical University
| | - Yuta Takagaki
- Department of Diabetology and Endocrinology Kanazawa Medical University
| | - Itaru Monno
- Department of Diabetology and Endocrinology Kanazawa Medical University
| | - Taro Hirai
- Department of Diabetology and Endocrinology Kanazawa Medical University
| | - Munehiro Kitada
- Department of Diabetology and Endocrinology Kanazawa Medical University
- Division of Anticipatory Molecular Food Science and Technology Medical Research Institute Kanazawa Medical University Uchinada, Ishikawa Japan
| | - Daisuke Koya
- Department of Diabetology and Endocrinology Kanazawa Medical University
- Division of Anticipatory Molecular Food Science and Technology Medical Research Institute Kanazawa Medical University Uchinada, Ishikawa Japan
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Sanni O, Terre'Blanche G. Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes. Rev Endocr Metab Disord 2021; 22:1073-1090. [PMID: 34165671 DOI: 10.1007/s11154-021-09668-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/21/2021] [Indexed: 10/21/2022]
Abstract
Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.
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Affiliation(s)
- Olakunle Sanni
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen), School of Health Sciences. North-West University (NWU), Potchefstroom, 2357, South Africa.
| | - G Terre'Blanche
- Centre of Excellence for Pharmaceutical Sciences (Pharmacen), School of Health Sciences. North-West University (NWU), Potchefstroom, 2357, South Africa
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4
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Jain S, Jacobson KA. Purinergic signaling in diabetes and metabolism. Biochem Pharmacol 2020; 187:114393. [PMID: 33359363 DOI: 10.1016/j.bcp.2020.114393] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/22/2022]
Abstract
Purinergic signaling, a concept originally formulated by the late Geoffrey Burnstock (1929-2020), was found to modulate pathways in every physiological system. In metabolic disorders there is a role for both adenosine receptors and P2 (nucleotide) receptors, of which there are two classes, i.e. P2Y metabotropic and P2X ionotropic receptors. The individual roles of the 19 receptors encompassed by this family have been dissected - and in many cases the effects associated with specific cell types, including adipocytes, skeletal muscle, liver cells and immune cells. It is suggested that ligands selective for each of the four adenosine receptors (A1, A2A, A2B and A3), and several of the P2 subtypes (e.g. P2Y6 or P2X7 antagonists) might have therapeutic potential for treating diabetes and obesity. This is a developing story with some conflicting conclusions relevant to drug discovery, which we summarize here.
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Affiliation(s)
- Shanu Jain
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA.
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Sacramento JF, Martins FO, Rodrigues T, Matafome P, Ribeiro MJ, Olea E, Conde SV. A 2 Adenosine Receptors Mediate Whole-Body Insulin Sensitivity in a Prediabetes Animal Model: Primary Effects on Skeletal Muscle. Front Endocrinol (Lausanne) 2020; 11:262. [PMID: 32411098 PMCID: PMC7198774 DOI: 10.3389/fendo.2020.00262] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/08/2020] [Indexed: 12/20/2022] Open
Abstract
Epidemiological studies showed that chronic caffeine intake decreased the risk of type 2 diabetes. Previously, we described that chronic caffeine intake prevents and reverses insulin resistance induced by hypercaloric diets and aging, in rats. Caffeine has several cellular mechanisms of action, being the antagonism of adenosine receptors the only attained with human coffee consumption. Here, we investigated the subtypes of adenosine receptors involved on the effects of chronic caffeine intake on insulin sensitivity and the mechanisms and sex differences behind this effect. Experiments were performed in male and female Wistar rats fed either a chow or high-sucrose (HSu) diet (35% of sucrose in drinking water) during 28 days, to induce insulin resistance. In the last 15 days of diet the animals were submitted to DPCPX (A1 antagonist, 0.4 mg/kg), SCH58261 (A2A antagonist, 0.5 mg/kg), or MRS1754 (A2B antagonist, 9.5 μg/kg) administration. Insulin sensitivity, fasting glycaemia, blood pressure, catecholamines, and fat depots were assessed. Expression of A1, A2A, A2B adenosine receptors and protein involved in insulin signaling pathways were evaluated in the liver, skeletal muscle, and visceral adipose tissue. UCP1 expression was measured in adipose tissue. Paradoxically, SCH58261 and MRS1754 decreased insulin sensitivity in control animals, whereas they both improved insulin response in HSu diet animals. DPCPX did not alter significantly insulin sensitivity in control or HSu animals, but reversed the increase in total and visceral fat induced by the HSu diet. In skeletal muscle, A1, A2A, and A2B adenosine receptor expression were increased in HSu group, an effect that was restored by SCH58261 and MRS1754. In the liver, A1, A2A expression was increased in HSu group, while A2B expression was decreased, being this last effect reversed by administration of MRS1754. In adipose tissue, A1 and A2A block upregulated the expression of these receptors. A2 adenosine antagonists restored impaired insulin signaling in the skeletal muscle of HSu rats, but did not affect liver or adipose insulin signaling. Our results show that adenosine receptors exert opposite effects on insulin sensitivity, in control and insulin resistant states and strongly suggest that A2 adenosine receptors in the skeletal muscle are the majors responsible for whole-body insulin sensitivity.
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Affiliation(s)
- Joana F. Sacramento
- CEDOC, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Fátima O. Martins
- CEDOC, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Tiago Rodrigues
- Faculty of Medicine, Institute of Physiology and Institute of Clinical and Biomedical Investigation of Coimbra (iCBR), University of Coimbra, Coimbra, Portugal
| | - Paulo Matafome
- Faculty of Medicine, Institute of Physiology and Institute of Clinical and Biomedical Investigation of Coimbra (iCBR), University of Coimbra, Coimbra, Portugal
- Escola Superior de Tecnologia da Saúde, Departmento de Ciências Complementares, Instituto Politécnico de Coimbra, Coimbra, Portugal
| | - Maria J. Ribeiro
- CEDOC, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Elena Olea
- Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, CSIC, Ciber de Enfermedades Respiratorias, CIBERES, Instituto de Biología y Genética Molecular, Instituto de Salud Carlos III, Universidad de Valladolid, Valladolid, Spain
| | - Silvia V. Conde
- CEDOC, NOVA Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisbon, Portugal
- *Correspondence: Silvia V. Conde
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Larijani B, Heshmat R, Ebrahimi-Rad M, Khatami S, Valadbeigi S, Saghiri R. Diagnostic Value of Adenosine Deaminase and Its Isoforms in Type II Diabetes Mellitus. Enzyme Res 2016; 2016:9526593. [PMID: 28050278 PMCID: PMC5165159 DOI: 10.1155/2016/9526593] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/14/2016] [Accepted: 11/01/2016] [Indexed: 11/29/2022] Open
Abstract
Background and Aims. In the present study, we have investigated the activity of adenosine deaminase (ADA) as a diagnostic marker in type 2 (or II) diabetes mellitus (T2DM). Design and Methods. The deaminase activity of ADA1 and ADA2 was determined in serum from 33 patients with type 2 (or II) diabetes mellitus and 35 healthy controls. We also determined the proportion of glycated hemoglobin (HbA1c). Results. Our results showed significant differences between total serum ADA (tADA) and ADA2 activities in the diabetic groups with HbA1c < 8 (%) and HbA1c ≥ 8 (%) with respect to the values in healthy individuals (p < 0.001). ADA2 activity in patients with high HbA1c was found to be much higher than that in patients with low HbA1c (p = 0.0001). In addition, total ADA activity showed a significant correlation with HbA1c (r = 0.6, p < 0.0001). Conclusions. Total serum ADA activity, specially that due to ADA2, could be useful test for the diagnosis of type 2 (or II) diabetes mellitus.
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Affiliation(s)
- Bagher Larijani
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Ramin Heshmat
- Chronic Diseases Research Center, Endocrinology and Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Shohreh Khatami
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
| | | | - Reza Saghiri
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
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Khorasanchi A, Arabi M, Akhavein A, Seyedabadi M, Eftekhari M, Javadi H, Nabipour I, Assadi M. Effect of Dipyridamole Injected for Myocardial Perfusion Imaging on Blood Glucose Concentration; A Preliminary Study. J Clin Diagn Res 2016; 10:TC24-7. [PMID: 27656528 DOI: 10.7860/jcdr/2016/19726.8373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 06/28/2016] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Dipyridamole inhibits adenosine reuptake and increases cyclic Adenosine Monophosphate (cAMP) levels in platelets, erythrocytes and endothelial cells, all of which influence blood glucose. Acute hyperglycaemia reduces endothelium-dependent vasodilation and suppresses coronary microcirculation; which, in theory, can alter the outcome of a radionuclide scan. AIM The present study was conducted with the aim to investigate the changes in blood glucose level of patients receiving dipyridamole for cardiac scan. MATERIALS AND METHODS A total of 293 patients (85 men and 208 women, age: 60.59±10.43 years) were included in the study. Fasting Blood Glucose (FBG) was measured before and 8 min after dipyridamole (0.568 mg/kg) injection during myocardial perfusion imaging. The data in different groups were analysed by paired t-test. RESULTS There was not a significant difference between first (106.89 ± 19.21mg/dL) and second (107.98 ± 17.57 mg/dL) FBG measurements (p= 0.293). However, when the patients were grouped based on the quartiles of first measurement, there was an increase in FBG following dipyridamole injection in the first quartile (mean difference: 7.15±21.27 mg/dL, p<0.01); in contrast, FBG levels showed a significant decrease after dipyridamole administration in the 4(th) quartile (mean difference: -9.53±18.20 mg/dL, p<0.001). The differences in 2(nd) and 3(rd) quartiles were negligible. The patients were divided into normal, ischemic and fixed lesions based on the outcome of scans, then the possible correlation of dipyridamole-induced FBG alteration and scan results were investigated. There were no significant difference between the FBG values before and after dipyridamole injection and the final outcome of scan. CONCLUSION The effects of dipyridamole on blood glucose highly depend on the initial blood glucose level.
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Affiliation(s)
- Amirreza Khorasanchi
- Assistant Professor, Department of Nuclear Medicine, Faculty of Medicine, Imam Hossein Hospital, Shahroud University of Medical Sciences , Shahroud, Iran
| | - Mohsen Arabi
- Assistant Professor, Department of Nuclear Medicine, Faculty of Medicine, Imam Hossein Hospital, Shahroud University of Medical Sciences , Shahroud, Iran
| | - Alireza Akhavein
- Assistant Professor, Department of Cardiology, Islamic Azad University Tehran Medical Branch, Tehran, Iran
| | - Mohammad Seyedabadi
- Assistant Professor, Department of Pharmacology, The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences , Bushehr, Iran
| | - Mansooreh Eftekhari
- Researcher, Department of Nuclear Medicine, Faculty of Medicine, Imam Hossein Hospital, Shahroud University of Medical Sciences , Shahroud, Iran
| | - Hamid Javadi
- Assistant Professor, Department of Nuclear Medicine, Golestan Research Center of Gastroenterology and Hepatology (GRCGH), Golestan University of Medical Sciences (GUOMS) , Gorgan, Iran
| | - Iraj Nabipour
- Professor, Department of Endocrinology, The Persian Gulf Tropical Medicine Research Center, Bushehr University of Medical Sciences , Bushehr, Iran
| | - Majid Assadi
- Professor, Department of Molecular Imaging and Radionuclide Therapy (MIRT), The Persian Gulf Nuclear Medicine Research Center, Bushehr University of Medical Sciences , Bushehr, Iran
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Tofovic SP, Salah EM, Smits GJ, Whalley ET, Ticho B, Deykin A, Jackson EK. Dual A1/A2B Receptor Blockade Improves Cardiac and Renal Outcomes in a Rat Model of Heart Failure with Preserved Ejection Fraction. J Pharmacol Exp Ther 2016; 356:333-40. [PMID: 26585572 PMCID: PMC4727158 DOI: 10.1124/jpet.115.228841] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/17/2015] [Indexed: 12/19/2022] Open
Abstract
Heart failure with preserved ejection fraction (HFpEF) is prevalent and often accompanied by metabolic syndrome. Current treatment options are limited. Here, we test the hypothesis that combined A1/A2B adenosine receptor blockade is beneficial in obese ZSF1 rats, an animal model of HFpEF with metabolic syndrome. The combined A1/A2B receptor antagonist 3-[4-(2,6-dioxo-1,3-dipropyl-7H-purin-8-yl)-1-bicyclo[2.2.2]octanyl]propanoic acid (BG9928) was administered orally (10 mg/kg/day) to obese ZSF1 rats (n = 10) for 24 weeks (from 20 to 44 weeks of age). Untreated ZSF1 rats (n = 9) served as controls. After 24 weeks of administration, BG9928 significantly lowered plasma triglycerides (in mg/dl: control group, 4351 ± 550; BG9928 group, 2900 ± 551) without adversely affecting plasma cholesterol or activating renin release. BG9928 significantly decreased 24-hour urinary glucose excretion (in mg/kg/day: control group, 823 ± 179; BG9928 group, 196 ± 80) and improved oral glucose tolerance, polydipsia, and polyuria. BG9928 significantly augmented left ventricular diastolic function in association with a reduction in cardiac vasculitis and cardiac necrosis. BG9928 significantly reduced 24-hour urinary protein excretion (in mg/kg/day: control group, 1702 ± 263; BG9928 group, 1076 ± 238), and this was associated with a reduction in focal segmental glomerulosclerosis, tubular atrophy, tubular dilation, and deposition of proteinaceous material in the tubules. These findings show that, in a model of HFpEF with metabolic syndrome, A1/A2B receptor inhibition improves hyperlipidemia, exerts antidiabetic actions, reduces HFpEF, improves cardiac histopathology, and affords renal protection. We conclude that chronic administration of combined A1/A2B receptor antagonists could be beneficial in patients with HFpEF, in particular those with comorbidities such as obesity, diabetes, and dyslipidemias.
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Affiliation(s)
- Stevan P Tofovic
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Eman M Salah
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Glenn J Smits
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Eric T Whalley
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Barry Ticho
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Aaron Deykin
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
| | - Edwin K Jackson
- Vascular Medicine Institute (S.P.T.) and the Departments of Medicine (S.P.T., E.K.J.), Pathology (E.M.S.), and Pharmacology and Chemical Biology (E.K.J.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Biogen Idec, Inc., Cambridge, Massachusetts (G.J.S., E.T.W., B.T., A.D.)
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Pirkmajer S, Kulkarni SS, Tom RZ, Ross FA, Hawley SA, Hardie DG, Zierath JR, Chibalin AV. Methotrexate promotes glucose uptake and lipid oxidation in skeletal muscle via AMPK activation. Diabetes 2015; 64:360-9. [PMID: 25338814 PMCID: PMC5703413 DOI: 10.2337/db14-0508] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Methotrexate (MTX) is a widely used anticancer and antirheumatic drug that has been postulated to protect against metabolic risk factors associated with type 2 diabetes, although the mechanism remains unknown. MTX inhibits 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC) and thereby slows the metabolism of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl-5'-monophosphate (ZMP) and its precursor AICAR, which is a pharmacological AMPK activator. We explored whether MTX promotes AMPK activation in cultured myotubes and isolated skeletal muscle. We found MTX markedly reduced the threshold for AICAR-induced AMPK activation and potentiated glucose uptake and lipid oxidation. Gene silencing of the MTX target ATIC activated AMPK and stimulated lipid oxidation in cultured myotubes. Furthermore, MTX activated AMPK in wild-type HEK-293 cells. These effects were abolished in skeletal muscle lacking the muscle-specific, ZMP-sensitive AMPK-γ3 subunit and in HEK-293 cells expressing a ZMP-insensitive mutant AMPK-γ2 subunit. Collectively, our findings underscore a role for AMPK as a direct molecular link between MTX and energy metabolism in skeletal muscle. Cotherapy with AICAR and MTX could represent a novel strategy to treat metabolic disorders and overcome current limitations of AICAR monotherapy.
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Affiliation(s)
- Sergej Pirkmajer
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Sameer S Kulkarni
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Robby Z Tom
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Fiona A Ross
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - Simon A Hawley
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, College of Life Sciences, University of Dundee, Dundee, Scotland, U.K
| | - Juleen R Zierath
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden Department of Physiology and Pharmacology, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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Koupenova M, Ravid K. Adenosine, adenosine receptors and their role in glucose homeostasis and lipid metabolism. J Cell Physiol 2013; 228:1703-1712. [PMID: 23460239 PMCID: PMC3849123 DOI: 10.1002/jcp.24352] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Revised: 02/09/2013] [Accepted: 02/12/2013] [Indexed: 01/12/2023]
Abstract
Adenosine is an endogenous metabolite that is released from all tissues and cells including liver, pancreas, muscle and fat, particularly under stress, intense exercise, or during cell damage. The role of adenosine in glucose homeostasis has been attributed to its ability to regulate, through its membrane receptors, processes such as insulin secretion, glucose release and clearance, glycogenolysis, and glycogenesis. Additionally, adenosine and its multiple receptors have been connected to lipid metabolism by augmenting insulin-mediated inhibition of lipolysis, and the subsequent increase in free fatty acids and glycerol levels. Furthermore, adenosine was reported to control liver cholesterol synthesis, consequently affecting plasma levels of cholesterol and triglycerides, and the amount of fat tissue. Alterations in the balance of glucose and lipid homeostasis have implications in both cardiovascular disease and diabetes. The ability of different adenosine receptors to activate and inhibit the same signaling cascades has made it challenging to study the influence of adenosine, adenosine analogs and their receptors in health and disease. This review focuses on the role and significance of different adenosine receptors in mediating the effect of adenosine on glucose and lipid homeostasis. J. Cell. Physiol. © 2013 Wiley Periodicals, Inc.
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Affiliation(s)
- Milka Koupenova
- Department of Medicine, Boston University School of Medicine, Boston, MA; Department of Biochemistry, Boston University School of Medicine, Boston, MA; Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA
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Faulhaber-Walter R, Jou W, Mizel D, Li L, Zhang J, Kim SM, Huang Y, Chen M, Briggs JP, Gavrilova O, Schnermann JB. Impaired glucose tolerance in the absence of adenosine A1 receptor signaling. Diabetes 2011; 60:2578-87. [PMID: 21831968 PMCID: PMC3178298 DOI: 10.2337/db11-0058] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE The role of adenosine (ADO) in the regulation of glucose homeostasis is not clear. In the current study, we used A1-ADO receptor (A1AR)-deficient mice to investigate the role of ADO/A1AR signaling for glucose homeostasis. RESEARCH DESIGN AND METHODS After weaning, A1AR(-/-) and wild-type mice received either a standard diet (12 kcal% fat) or high-fat diet (HFD; 45 kcal% fat). Body weight, fasting plasma glucose, plasma insulin, and intraperitoneal glucose tolerance tests were performed in 8-week-old mice and again after 12-20 weeks of subsequent observation. Body composition was quantified by magnetic resonance imaging and epididymal fat-pad weights. Glucose metabolism was investigated by hyperinsulinemic-euglycemic clamp studies. To describe pathophysiological mechanisms, adipokines and Akt phosphorylation were measured. RESULTS A1AR(-/-) mice were significantly heavier than wild-type mice because of an increased fat mass. Fasting plasma glucose and insulin were significantly higher in A1AR(-/-) mice after weaning and remained higher in adulthood. An intraperitoneal glucose challenge disclosed a significantly slower glucose clearance in A1AR(-/-) mice. An HFD enhanced this phenotype in A1AR(-/-) mice and unmasked a dysfunctional insulin secretory mechanism. Insulin sensitivity was significantly impaired in A1AR(-/-) mice on the standard diet shortly after weaning. Clamp studies detected a significant decrease of net glucose uptake in A1AR(-/-) mice and a reduced glucose uptake in muscle and white adipose tissue. Effects were not triggered by leptin deficiency but involved a decreased Akt phosphorylation. CONCLUSIONS ADO/A1AR signaling contributes importantly to insulin-controlled glucose homeostasis and insulin sensitivity in C57BL/6 mice and is involved in the metabolic regulation of adipose tissue.
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Affiliation(s)
- Robert Faulhaber-Walter
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
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12
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Figler RA, Wang G, Srinivasan S, Jung DY, Zhang Z, Pankow JS, Ravid K, Fredholm B, Hedrick CC, Rich SS, Kim JK, LaNoue KF, Linden J. Links between insulin resistance, adenosine A2B receptors, and inflammatory markers in mice and humans. Diabetes 2011; 60:669-79. [PMID: 21270276 PMCID: PMC3028369 DOI: 10.2337/db10-1070] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine the mechanisms by which blockade of adenosine A(2B) receptors (A(2B)Rs) reduces insulin resistance. RESEARCH DESIGN AND METHODS We investigated the effects of deleting or blocking the A(2B)R on insulin sensitivity using glucose tolerance tests (GTTs) and hyperinsulinemic-euglycemic clamps in mouse models of type 2 diabetes. The effects of diabetes on A(2B)R transcription and signaling were measured in human and mouse macrophages and mouse endothelial cells. In addition, tag single nucleotide polymorphisms (SNPs) in ~42 kb encompassing the A(2B)R gene, ADORA2B, were evaluated for associations with markers of diabetes and inflammation. RESULTS Treatment of mice with the nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadensoine (NECA) increased fasting blood glucose and slowed glucose disposal during GTTs. These responses were inhibited by A(2B)R deletion or blockade and minimally affected by deletion of A(1)Rs or A(2A)Rs. During hyperinsulinemic-euglycemic clamp of diabetic KKA(Y) mice, A(2B)R antagonism increased glucose infusion rate, reduced hepatic glucose production, and increased glucose uptake into skeletal muscle and brown adipose tissue. Diabetes caused a four- to sixfold increase in A(2B)R mRNA in endothelial cells and macrophages and resulted in enhanced interleukin (IL)-6 production in response to NECA due to activation of protein kinases A and C. Five consecutive tag SNPs in ADORA2B were highly correlated with IL-6 and C-reactive protein (CRP). Diabetes had a highly significant independent effect on variation in inflammatory markers. The strength of associations between several ADORA2B SNPs and inflammatory markers was increased when accounting for diabetes status. CONCLUSIONS Diabetes affects the production of adenosine and the expression of A(2B)Rs that stimulate IL-6 and CRP production, insulin resistance, and the association between ADORA2B SNPs and inflammatory markers. We hypothesize that increased A(2B)R signaling in diabetes increases insulin resistance in part by elevating proinflammatory mediators. Selective A(2B)R blockers may be useful to treat insulin resistance.
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Affiliation(s)
- Robert A. Figler
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
| | - Guoquan Wang
- Adenosine Therapeutics Group of PGxHealth, Clinical Data Incorporated, Charlottesville, Virginia
| | - Susseela Srinivasan
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
| | - Dae Young Jung
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Zhiyou Zhang
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - James S. Pankow
- Department of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota
| | - Katya Ravid
- Department of Biochemistry, Boston University, Boston, Massachusetts
| | - Bertil Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Catherine C. Hedrick
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
| | - Stephen S. Rich
- Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia
| | - Jason K. Kim
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Kathryn F. LaNoue
- Department of Biochemistry, Boston University, Boston, Massachusetts
| | - Joel Linden
- Cardiovascular Research Center, University of Virginia, Charlottesville, Virginia
- Corresponding author: Joel Linden,
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Calvin AD, Misra S, Pflueger A. Contrast-induced acute kidney injury and diabetic nephropathy. Nat Rev Nephrol 2010; 6:679-88. [PMID: 20877303 DOI: 10.1038/nrneph.2010.116] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Contrast-induced acute kidney injury (CIAKI) is a leading cause of iatrogenic renal failure. Multiple studies have shown that patients with diabetic nephropathy are at high risk of CIAKI. This Review presents an overview of the pathogenesis of CIAKI in patients with diabetic nephropathy and discusses the currently available and potential future strategies for CIAKI prevention.
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Affiliation(s)
- Andrew D Calvin
- Department of Medicine, Mayo Clinic College of Medicine, SW, Rochester, MN 55905, USA
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Gloria-Bottini F, Pietropolli A, Coppeta L, Magrini A, Bergamaschi A, Bottini E. The genetics of feto-placental development: a study of acid phosphatase locus 1 and adenosine deaminase polymorphisms in a consecutive series of newborn infants. Reprod Biol Endocrinol 2008; 6:38. [PMID: 18768081 PMCID: PMC2569950 DOI: 10.1186/1477-7827-6-38] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Accepted: 09/03/2008] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Acid phosphatase locus 1 and adenosine deaminase locus 1 polymorphisms show cooperative effects on glucose metabolism and immunological functions. The recent observation of cooperation between the two systems on susceptibility to repeated spontaneous miscarriage prompted us to search for possible interactional effects between these genes and the correlation between birth weight and placental weight. Deviation from a balanced development of the feto-placental unit has been found to be associated with perinatal morbidity and mortality and with cardiovascular diseases in adulthood. METHODS We examined 400 consecutive newborns from the Caucasian population of Rome. Birth weight, placental weight, and gestational length were registered. Acid phosphatase locus 1 and adenosine deaminase locus 1 phenotypes were determined by starch gel electrophoresis and correlation analysis was performed by SPSS programs. Informed verbal consent to participate in the study was obtained from the mothers. RESULTS Highly significant differences in birth weight-placental weight correlations were observed among acid phosphatase locus 1 phenotypes (p = 0.005). The correlation between birth weight and placental weight was markedly elevated in subjects carrying acid phosphatase locus 1 phenotypes with medium-low F isoform concentration (A, CA and CB phenotypes) compared to those carrying acid phosphatase locus 1 phenotypes with medium-high F isoform concentration (BA and B phenotypes) (p = 0.002). Environmental and developmental variables were found to exert a significant effect on birth weight-placental weight correlation in subjects with medium-high F isoform concentrations, but only a marginal effect was observed in those with medium-low F isoform concentrations. The correlation between birth weight and placental weight is higher among carriers of the adenosine deaminase locus 1 allele*2, which is associated with low activity, than in homozygous adenosine deaminase locus 1 phenotype 1 carriers (p = 0.04). The two systems show a cooperative effect on the correlation between birth weight and placental weight: the highest value is observed in newborns carrying adenosine deaminase locus 1 allele*2 and acid phosphatase locus 1 phenotypes with medium-low F isoform concentration (p = 0.005). CONCLUSION These data suggest that zygotes with low adenosine deaminase locus 1 activity and low F activity may experience the most favourable intrauterine conditions for a balanced development of the feto-placental unit.
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Affiliation(s)
- Fulvia Gloria-Bottini
- Division of Human Population Biopathology and Environmental Pathology, Department of Biopathology and Imaging Diagnostics, University of Rome Tor Vergata, Rome, Italy
| | - Adalgisa Pietropolli
- Division of Obstetrics and Gynecology, Department of Surgery, University of Rome Tor Vergata, School of Medicine, Rome, Italy
| | - Luca Coppeta
- Division of Human Population Biopathology and Environmental Pathology, Department of Biopathology and Imaging Diagnostics, University of Rome Tor Vergata, Rome, Italy
| | - Andrea Magrini
- Division of Human Population Biopathology and Environmental Pathology, Department of Biopathology and Imaging Diagnostics, University of Rome Tor Vergata, Rome, Italy
| | - Antonio Bergamaschi
- Institute of Occupational Health Medicine, Catholic University of Holy Hearth, Rome, Italy
| | - Egidio Bottini
- Division of Human Population Biopathology and Environmental Pathology, Department of Biopathology and Imaging Diagnostics, University of Rome Tor Vergata, Rome, Italy
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Coope GJ, Atkinson AM, Allott C, McKerrecher D, Johnstone C, Pike KG, Holme PC, Vertigan H, Gill D, Coghlan MP, Leighton B. Predictive blood glucose lowering efficacy by Glucokinase activators in high fat fed female Zucker rats. Br J Pharmacol 2006; 149:328-35. [PMID: 16921397 PMCID: PMC2014270 DOI: 10.1038/sj.bjp.0706848] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Glucokinase (GK) is the rate-limiting enzyme of hepatic glucose metabolism and acts as a sensor for glucose-stimulated insulin release in beta-cells. Here we examine whether the lowering of blood glucose levels in the rat by small molecule glucokinase activators (GKAs) can be predicted from in vitro enzyme potencies and plasma compound exposure. EXPERIMENTAL APPROACH We developed an insulin resistant and hyperinsulinemic animal model, the high fat fed female Zucker (fa/fa) rat (HFFZ), and measured the acute in vivo glucose-lowering efficacy of a number of GKAs in an oral glucose tolerance test. KEY RESULTS Four GKAs (at 1 to 30 mg kg(-1)), with different in vitro enzyme potencies, dose-dependently improved oral glucose tolerance in HFFZ rats (10-40% decrease glucose area under the curve (AUC) from vehicle control). The extent of glucose lowering, or the pharmacodynamic (PD) effect, of a GKA was directly related to the total compound concentration in the plasma; the pharmacokinetic (PK) measurement. This PK-PD relationship was extended across a series of GKAs by accounting for differences in protein binding and in the in vitro potency. CONCLUSIONS AND IMPLICATIONS When the unbound GKA compound level is greater than the in vitro enzyme potency there was significant blood glucose lowering in vivo. This latter relationship was upheld in non-diabetic Wistar rats orally dosed with a GKA. The robust and predictive nature of the PK-PD relationship for GKAs may prove of value in testing these agents in early human clinical studies.
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Affiliation(s)
- G J Coope
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - A M Atkinson
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - C Allott
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - D McKerrecher
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - C Johnstone
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - K G Pike
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - P C Holme
- Syngenta Central Toxicology Department Macclesfield, Cheshire, UK
| | - H Vertigan
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - D Gill
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - M P Coghlan
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - B Leighton
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
- Author for correspondence:
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Frühbeck G, Gómez-Ambrosi J, Salvador J. Leptin-induced lipolysis opposes the tonic inhibition of endogenous adenosine in white adipocytes. FASEB J 2001; 15:333-40. [PMID: 11156949 DOI: 10.1096/fj.00-0249com] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The aim of the present study was to gain insight into the signaling pathway used by leptin to stimulate lipolysis. The lipolytic rate of white adipocytes from sex- and age-matched lean (+/+) and fa/fa rats was determined in the absence or presence of leptin together with a number of agents acting at different levels of the signaling cascade. Leptin did not modify FSK-, dbcAMP-, and IBMX-stimulated lipolysis. Lipolysis can also be maximally stimulated by lowering media adenosine levels with adenosine deaminase (ADA), i.e., in the ligand-free state. Although ADA produced near maximal lipolysis in adipocytes of lean animals, only half of the maximal lipolytic rate (50.9+/-3.2%) was achieved in fat cells from fa/fa rats (P=0.0034). In adipocytes from lean animals preincubated with ADA, leptin caused a concentration-related stimulation of lipolysis (P=0.0001). However, leptin had no effect on the lipolytic activity of adipocytes in the ligand-free state from fa/fa rats. The adenosine A1 receptor agonist CPA effectively inhibited basal lipolysis in both lean and obese adipocytes (P=0.0001 and P=0.0090, respectively). Leptin had no effect on the lipolytic rate of adipocytes isolated from fa/fa rats and preincubated with CPA. When adipocytes were incubated with the A1 receptor antagonist DPCPX, a significant increase in glycerol release was observed in fa/fa fat cells (P=0.009), whereas cells isolated from lean rats showed no differences to ADA-stimulated lipolysis. After pretreatment with PTX, which inactivates receptor-mediated Gi function, adipocytes of obese rats became as responsive to the stimulatory actions of ISO as cells from lean rats (P=0.0090 vs. ISO in fa/fa rats; P=0.2416 vs. lean rats, respectively). PTX treatment of lean cells, however, did not alter their response to this lipolytic agent. It can be concluded that the lipolytic effect of leptin is located at the adenylate cyclase/Gi proteins level and that leptin-induced lipolysis opposes the tonic inhibition of endogenous adenosine in white adipocytes.
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Affiliation(s)
- G Frühbeck
- Metabolic Research Laboratory, University of Navarra, and, Department of Endocrinology, Clínica Universitaria de Navarra, 31008-Pamplona, Spain.
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Crist GH, Xu B, Lanoue KF, Lang CH. Tissue-specific effects of in vivo adenosine receptor blockade on glucose uptake in Zucker rats. FASEB J 1998; 12:1301-8. [PMID: 9761773 DOI: 10.1096/fasebj.12.13.1301] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Previous studies have shown that treatment of obese Zucker rats with the adenosine receptor antagonist 1,3-dipropyl-8-(p-acrylic) phenyl xanthine (BWA1433) improves intraperitoneal glucose tolerance. In this study, a euglycemic hyperinsulinemic clamp was performed on obese (fa/fa) and lean (Fa/fa) Zucker rats that had been treated orally with BWA1433 or vehicle for 1 wk. A constant infusion of [3H]glucose was initiated in fasted animals to measure basal whole body glucose kinetics. No differences in glucose concentration or rates of glucose production/disappearance were observed between lean or obese animals with or without BWA1433. During the euglycemic hyperinsulinemic clamp, whole body glucose disposal in obese Zucker rats was only 22% of that observed in lean animals. BWA1433 treatment increased glucose disposal by 88% in obese Zucker rats. At the end of the clamp, [14C]-2-deoxyglucose was injected to determine tissue-specific differences in glucose uptake. Gastrocnemius, soleus, heart, and liver of untreated obese animals had significantly lower glucose uptake than lean controls under hyperinsulinemic conditions. BWA1433 treatment of obese animals increased glucose uptake in gastrocnemius and soleus muscles by 44 and 47%, respectively. Conversely, BWA1433 treatment decreased glucose uptake in adipose tissue by 54 and 49% in obese and lean Zucker rats, respectively. In summary, BWA1433 improves glucose tolerance by increasing glucose uptake in skeletal muscle while decreasing glucose uptake by adipose tissue. This study suggests that insulin resistance in obese Zucker rats is tissue specific and that signaling from adenosine receptors may be a factor contributing to tissue-specific insulin resistance.
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Affiliation(s)
- G H Crist
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033 0850,
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