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Dede E, Liapis D, Davos C, Katsimpoulas M, Varela A, Mpotis I, Kostomitsopoulos N, Kadoglou NPE. The effects of exercise training on cardiac matrix metalloproteinases activity and cardiac function in mice with diabetic cardiomyopathy. Biochem Biophys Res Commun 2022; 586:8-13. [PMID: 34818584 DOI: 10.1016/j.bbrc.2021.11.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/03/2021] [Indexed: 11/17/2022]
Abstract
AIM To evaluate the effects of exercise training (ET) on cardiac extracellular matrix (ECM) proteins homeostasis and cardiac dysfunction in mice with diabetic cardiomyopathy. METHODS Thirty-six male C57BL/6 mice were randomized into 3 groups for 8 weeks (12mice/group): Diabetic control-DC: Diabetes was induced by single streptozotocin injection (200 mg/kg i.p.); Diabetic exercise-DE: Diabetic mice underwent ET program on motorized-treadmill (6-times/week, 60min/session); Non-diabetic control-NDC: Vehicle-treated, sedentary, non-diabetic mice served as controls. Before euthanasia, all groups underwent transthoracic echocardiography (TTE). Post-mortem, left-ventricle (LV) samples were histologically analysed for ECM proteins (collagen, elastin), matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). RESULTS DC group showed significantly higher cardiac contents of collagen and MMP-9 and lower elastic concentration than NDC (p < 0.001). The implementation of ET completely outweighed those diabetes-induced changes (DE vs NDC, p > 0.05). TIMP-1 levels significantly increased across all groups (DC: 18.98 ± 3.47%, DE: 24.24 ± 2.36%, NDC: 46.36 ± 5.91%; p < 0.05), while MMP-9/TIMP-1 ratio followed a reverse pattern. ET tended to increase MMP-2 concentrations versus DC (p = 0.055), but did not achieve non-diabetic levels (p < 0.05). TIMP-2 cardiac concentrations remained unaltered throughout the study (p > 0.05). Importantly, ET ameliorated both LV end-systolic internal diameter (LVESD) (p < 0.001) and the percentage of LV fractional shortening (FS%) (p = 0.006) compared to DC. Despite that favorable effect, the cardiac function level of DE group remained worse than NDC group (%FS: p = 0.002; LVESD: p < 0.001). CONCLUSION Systemic ET may favorably change ECM proteins, MMP-9 and TIMP-1 cardiac concentrations in mice with diabetic cardiomyopathy. Those results were associated with partial improvement of echocardiography-assessed cardiac function, indicating a therapeutic effect of ET in diabetic cardiomyopathy.
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Affiliation(s)
- Eleni Dede
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
| | - Dimitrios Liapis
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
| | - Constantinos Davos
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
| | - Michalis Katsimpoulas
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
| | - Aimilia Varela
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
| | - Ioannis Mpotis
- Center of Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Greece
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Erdogan BR, Michel MC, Arioglu-Inan E. Expression and Signaling of β-Adrenoceptor Subtypes in the Diabetic Heart. Cells 2020; 9:cells9122548. [PMID: 33256212 PMCID: PMC7759850 DOI: 10.3390/cells9122548] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/20/2020] [Accepted: 11/24/2020] [Indexed: 12/18/2022] Open
Abstract
Diabetes is a chronic, endocrine disorder that effects millions of people worldwide. Cardiovascular complications are the major cause of diabetes-related morbidity and mortality. Cardiac β1- and β2-adrenoceptor (AR) stimulation mediates positive inotropy and chronotropy, whereas β3-AR mediates negative inotropic effect. Changes in β-AR responsiveness are thought to be an important factor that contributes to the diabetic cardiac dysfunction. Diabetes related changes in β-AR expression, signaling, and β-AR mediated cardiac function have been studied by several investigators for many years. In the present review, we have screened PubMed database to obtain relevant articles on this topic. Our search has ended up with wide range of different findings about the effect of diabetes on β-AR mediated changes both in molecular and functional level. Considering these inconsistent findings, the effect of diabetes on cardiac β-AR still remains to be clarified.
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Affiliation(s)
- Betul R. Erdogan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, 06560 Ankara, Turkey;
- Department of Pharmacology, Faculty of Pharmacy, Izmir Katip Celebi University, 35620 Izmir, Turkey
| | - Martin C. Michel
- Department of Pharmacology, Johannes Gutenberg University, 55131 Mainz, Germany;
| | - Ebru Arioglu-Inan
- Department of Pharmacology, Faculty of Pharmacy, Ankara University, 06560 Ankara, Turkey;
- Correspondence:
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Boardman NT, Rossvoll L, Lund J, Hafstad AD, Aasum E. 3-Weeks of Exercise Training Increases Ischemic-Tolerance in Hearts From High-Fat Diet Fed Mice. Front Physiol 2019; 10:1274. [PMID: 31632301 PMCID: PMC6783811 DOI: 10.3389/fphys.2019.01274] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 09/19/2019] [Indexed: 12/15/2022] Open
Abstract
Physical activity is an efficient strategy to delay development of obesity and insulin resistance, and thus the progression of obesity/diabetes-related cardiomyopathy. In support of this, experimental studies using animal models of obesity show that chronic exercise prevents the development of obesity-induced cardiac dysfunction (cardiomyopathy). Whether exercise also improves the tolerance to ischemia-reperfusion in these models is less clear, and may depend on the type of exercise procedure as well as time of initiation. We have previously shown a reduction in ischemic-injury in diet-induced obese mice, when the exercise was started prior to the development of cardiac dysfunction in this model. In the present study, we aimed to explore the effect of exercise on ischemic-tolerance when exercise was initiated after the development obesity-mediated. Male C57BL/6J mice were fed a high-fat diet (HFD) for 20–22 weeks, where they were subjected to high-intensity interval training (HIT) during the last 3 weeks of the feeding period. Sedentary HFD fed and chow fed mice served as controls. Left-ventricular (LV) post-ischemic functional recovery and infarct size were measured in isolated perfused hearts. We also assessed the effect of 3-week HIT on mitochondrial function and myocardial oxygen consumption (MVO2). Sedentary HFD fed mice developed marked obesity and insulin resistance, and demonstrated reduced post-ischemic cardiac functional recovery and increased infarct size. Three weeks of HIT did not induce cardiac hypertrophy and only had a mild effect on obesity and insulin resistance. Despite this, HIT improved post-ischemic LV functional recovery and reduced infarct size. This increase in ischemic-tolerance was accompanied by an improved mitochondrial function as well as reduced MVO2. The present study highlights the beneficial effects of exercise training with regard to improving the ischemic-tolerance in hearts with cardiomyopathy following obesity and insulin resistance. This study also emphasizes the exercise-induced improvement of cardiac energetics and mitochondrial function in obesity/diabetes.
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Affiliation(s)
- Neoma T Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Line Rossvoll
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Jim Lund
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Anne D Hafstad
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Ellen Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT - The Arctic University of Norway, Tromsø, Norway
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4
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Abstract
Perivascular adipose tissue (PVAT) is no longer recognised as simply a structural support for the vasculature, and we now know that PVAT releases vasoactive factors which modulate vascular function. Since the discovery of this function in 1991, PVAT research is rapidly growing and the importance of PVAT function in disease is becoming increasingly clear. Obesity is associated with a plethora of vascular conditions; therefore, the study of adipocytes and their effects on the vasculature is vital. PVAT contains an adrenergic system including nerves, adrenoceptors and transporters. In obesity, the autonomic nervous system is dysfunctional; therefore, sympathetic innervation of PVAT may be the key mechanistic link between increased adiposity and vascular disease. In addition, not all obese people develop vascular disease, but a common feature amongst those that do appears to be the inflammatory cell population in PVAT. This review will discuss what is known about sympathetic innervation of PVAT, and the links between nerve activation and inflammation in obesity. In addition, we will examine the therapeutic potential of exercise in sympathetic stimulation of adipose tissue.
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Affiliation(s)
- Sophie N Saxton
- Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Core Technology Facility (3rd floor), 46 Grafton Street, M13 9NT, Manchester, UK.
| | - Sarah B Withers
- Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Core Technology Facility (3rd floor), 46 Grafton Street, M13 9NT, Manchester, UK
- School of Environment and Life Sciences, University of Salford, Manchester, UK
| | - Anthony M Heagerty
- Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Core Technology Facility (3rd floor), 46 Grafton Street, M13 9NT, Manchester, UK
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5
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Boardman NT, Hafstad AD, Lund J, Rossvoll L, Aasum E. Exercise of obese mice induces cardioprotection and oxygen sparing in hearts exposed to high-fat load. Am J Physiol Heart Circ Physiol 2017; 313:H1054-H1062. [DOI: 10.1152/ajpheart.00382.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 08/03/2017] [Accepted: 08/08/2017] [Indexed: 02/03/2023]
Abstract
Exercise training is a potent therapeutic approach in obesity and diabetes that exerts protective effects against the development of diabetic cardiomyopathy and ischemic injury. Acute increases in circulating fatty acids (FAs) during an ischemic insult can challenge the heart, since high FA load is considered to have adverse cardiac effects. In the present study, we tested the hypothesis that exercise-induced cardiac effects in diet-induced obese mice are abrogated by an acute high FA load. Diet-induced obese mice were fed a high-fat diet (HFD) for 20 wk. They were exercised using moderate- and/or high-intensity exercise training (MIT and HIT, respectively) for 10 or 3 wk, and isolated perfused hearts from these mice were exposed to a high FA load. Sedentary HFD mice served as controls. Ventricular function and myocardial O2 consumption were assessed after 10 wk of HIT and MIT, and postischemic functional recovery and infarct size were examined after 3 wk of HIT. In addition to improving aerobic capacity and reducing obesity and insulin resistance, long-term exercise ameliorated the development of diet-induced cardiac dysfunction. This was associated with improved mechanical efficiency because of reduced myocardial oxygen consumption. Although to a lesser extent, 3-wk HIT also increased aerobic capacity and decreased obesity and insulin resistance. HIT also improved postischemic functional recovery and reduced infarct size. Event upon the exposure to a high FA load, short-term exercise induced an oxygen-sparing effect. This study therefore shows that exercise-induced cardioprotective effects are present under hyperlipidemic conditions and highlights the important role of myocardial energetics during ischemic stress. NEW & NOTEWORTHY The exercise-induced cardioprotective effects in obese hearts are present under hyperlipidemic conditions, comparable to circulating levels of FA occurring with an ischemic insult. Myocardial oxygen sparing is associated with this effect, despite the general notion that high fat can decrease cardiac efficiency. This highlights the role of myocardial energetics during ischemic stress.
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Affiliation(s)
- Neoma T. Boardman
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Anne D. Hafstad
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Jim Lund
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Line Rossvoll
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Ellen Aasum
- Cardiovascular Research Group, Faculty of Health Sciences, Department of Medical Biology, UiT-The Arctic University of Norway, Tromsø, Norway
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Mahmoud AM. Exercise Amaliorates Metabolic Disturbances and Oxidative Stress in Diabetic Cardiomyopathy: Possible Underlying Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:207-230. [DOI: 10.1007/978-981-10-4307-9_12] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
Macrovascular complications of diabetes, including diabetic cardiovascular disease (CVD), occur through a number of hyperglycaemia-induced mechanisms that include generation of oxidative stress, accumulation of advanced glycation end-products (AGE) and activation of protein kinase C (PKC). Cardiac oxidative stress is associated with increased cardiac fibrosis and hypertrophy, and reduced cardiac performance and contractility, leading to severe cardiac dysfunction and potentially fatal cardiac events. It occurs under conditions of excessive synthesis of reactive oxygen species (ROS). The ensuing activation of transcription factors such as nuclear factor-κB produces inflammation, fibrosis, hypertrophy and further oxidative stress, which itself causes DNA and membrane damage. This review summarises the mechanisms that generate ROS in the diabetic heart: mitochondrial electron leakage, activity of ROS-generating enzymes such as NADPH oxidase, xanthine oxidase and 12/15 lipoxygenase, uncoupling of nitric oxide synthase, accumulation of AGEs and activation of PKC. There is interaction between many of these ROS-generating pathways, with data from a range of published studies indicating that a common upstream pathway is the interaction of AGEs with their receptor (RAGE), which further promotes ROS synthesis. Therefore, agents targeted at decreasing ROS production have been investigated for prevention or treatment of diabetic CVD through reducing oxidative stress, and this review considers some of the studies carried out with anti-oxidant therapies and the feasibility of this approach for protecting against diabetic cardiomyopathy.
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Affiliation(s)
- Alyssa Faria
- Diabetes Research Group, Division of Diabetes & Nutritional Sciences, King's College London, London SE1 1UL, United Kingdom
| | - Shanta J Persaud
- Diabetes Research Group, Division of Diabetes & Nutritional Sciences, King's College London, London SE1 1UL, United Kingdom.
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Exercise Training Attenuates Upregulation of p47(phox) and p67(phox) in Hearts of Diabetic Rats. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:5868913. [PMID: 26989452 PMCID: PMC4771908 DOI: 10.1155/2016/5868913] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/24/2015] [Accepted: 12/21/2015] [Indexed: 01/22/2023]
Abstract
Exercise training (ExT) is currently being used as a nonpharmacological strategy to improve cardiac function in diabetic patients. However, the molecular mechanism(s) underlying its beneficial effects remains poorly understood. Oxidative stress is known to play a key role in the pathogenesis of diabetic cardiomyopathy and one of the enzyme systems that produce reactive oxygen species is NADH/NADPH oxidase. The goal of this study was to investigate the effect of streptozotocin- (STZ-) induced diabetes on expression of p47(phox) and p67(phox), key regulatory subunits of NADPH oxidase, in cardiac tissues and determine whether ExT can attenuate these changes. Four weeks after STZ treatment, expression of p47(phox) and p67(phox) increased 2.3-fold and 1.6-fold, respectively, in left ventricles of diabetic rats and these increases were attenuated with three weeks of ExT, initiated 1 week after onset of diabetes. In atrial tissues, there was increased expression of p47(phox) (74%), which was decreased by ExT in diabetic rats. Furthermore, increased collagen III levels in diabetic hearts (52%) were significantly reduced by ExT. Taken together, ExT attenuates the increased expression of p47(phox) and p67(phox) in the hearts of diabetic rats which could be an underlying mechanism for improving intracardiac matrix and thus cardiac function and prevent cardiac remodeling in diabetic cardiomyopathy.
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da Silva E, Natali AJ, da Silva MF, Gomes GDJ, da Cunha DNQ, Toledo MM, Drummond FR, Ramos RMS, Dos Santos EC, Novaes RD, de Oliveira LL, Maldonado IRDSC. Swimming training attenuates the morphological reorganization of the myocardium and local inflammation in the left ventricle of growing rats with untreated experimental diabetes. Pathol Res Pract 2016; 212:325-34. [PMID: 26896925 DOI: 10.1016/j.prp.2016.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 12/19/2015] [Accepted: 02/01/2016] [Indexed: 01/27/2023]
Abstract
Diabetic cardiomyopathy is associated with cardiac remodeling, myocardial dysfunction, low-grade inflammation, and reduced cardiac adiponectin in patients with type 1 diabetes mellitus (T1DM). Alternatively, physical exercise is an important strategy for the management of diabetes. This study aimed to investigate the influence of low-intensity swimming training in cardiac cytokines, structural remodeling, and cardiomyocyte contractile dysfunction in growing rats with untreated experimental DM. Thirty-day-old male Wistar rats were divided into four groups (n=14, per group): sedentary control (SC), exercised control (EC), sedentary diabetic (SD), and exercised diabetic (ED). Diabetes was induced by streptozotocin (60 mg kg(-1), i.p.). Animals from exercised groups swam (5 days/week, 90 min/day, loading up to 5% body weight around the animal's chest) for 8 weeks. The left ventricle (LV) was removed for molecular, morphological, and cardiomyocyte mechanical analysis. Diabetic animals presented cardiac remodeling with myocardial histoarchitectural disorganization, fibrosis, and necrosis. The capillary density was lower in diabetic animals. LV cardiomyocytes from diabetic animals exhibited more prolonged time to the peak of contraction and time to half relaxation than those from control animals. The cardiac levels of interleukin 10, nitric oxide, and total and high molecular weight (HMW) adiponectin were significantly decreased in diabetic animals. Exercise training reduced the level of TNF-α, increased capillary density, and attenuated the histopathological parameters assessed in diabetic rats. In conclusion, the cardiac structural remodeling coexists with reduced levels of total and HMW adiponectin, inflammation, and cardiomyocyte contractility dysfunction in experimental DM. More important, low-intensity swimming training attenuates part of these pathological changes, indicating the beneficial role for exercise in untreated T1DM.
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Affiliation(s)
- Edson da Silva
- Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil; Department of Basic Sciences, Federal University of Jequitinhonha and Mucuri Valleys, Diamantina, MG, Brazil.
| | - Antônio José Natali
- Department of Physical Education, Federal University of Viçosa, Viçosa, MG, Brazil
| | | | - Gilton de Jesus Gomes
- Department of Physical Education, Federal University of Viçosa, Viçosa, MG, Brazil; Department of Physical Education, Federal University of Jequitinhonha and Mucuri Valleys, Diamantina, MG, Brazil
| | | | | | - Filipe Rios Drummond
- Department of Physical Education, Federal University of Viçosa, Viçosa, MG, Brazil
| | | | - Eliziária Cardoso Dos Santos
- Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil; Faculty of Medicine, Federal University of Jequitinhonha and Mucuri Valleys, Diamantina, MG, Brazil
| | - Rômulo Dias Novaes
- Department of General Biology, Federal University of Viçosa, Viçosa, MG, Brazil; Biomedical Sciences Institute, Federal University of Alfenas, MG, Brazil
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Hafstad AD, Boardman N, Aasum E. How exercise may amend metabolic disturbances in diabetic cardiomyopathy. Antioxid Redox Signal 2015; 22:1587-605. [PMID: 25738326 PMCID: PMC4449627 DOI: 10.1089/ars.2015.6304] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
SIGNIFICANCE Over-nutrition and sedentary lifestyle has led to a worldwide increase in obesity, insulin resistance, and type 2 diabetes (T2D) associated with an increased risk of development of cardiovascular disorders. Diabetic cardiomyopathy, independent of hypertension or coronary disease, is induced by a range of systemic changes and may through multiple processes result in functional and structural cardiac derangements. The pathogenesis of this cardiomyopathy is complex and multifactorial, and it will eventually lead to reduced cardiac working capacity and increased susceptibility to ischemic injury. RECENT ADVANCES Metabolic disturbances such as altered lipid handling and substrate utilization, decreased mechanical efficiency, mitochondrial dysfunction, disturbances in nonoxidative glucose pathways, and increased oxidative stress are hallmarks of diabetic cardiomyopathy. Interestingly, several of these disturbances are found to precede the development of cardiac dysfunction. CRITICAL ISSUES Exercise training is effective in the prevention and treatment of obesity and T2D. In addition to its beneficial influence on diabetes/obesity-related systemic changes, it may also amend many of the metabolic disturbances characterizing the diabetic myocardium. These changes are due to both indirect effects, exercise-mediated systemic changes, and direct effects originating from the high contractile activity of the heart during physical training. FUTURE DIRECTIONS Revealing the molecular mechanisms behind the beneficial effects of exercise training is of considerable scientific value to generate evidence-based therapy and in the development of new treatment strategies.
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Affiliation(s)
- Anne D Hafstad
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Neoma Boardman
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Ellen Aasum
- Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromsø, Norway
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Bussey CT, de Leeuw AE, Lamberts RR. Increased haemodynamic adrenergic load with isoflurane anaesthesia in type 2 diabetic and obese rats in vivo. Cardiovasc Diabetol 2014; 13:161. [PMID: 25496763 PMCID: PMC4266208 DOI: 10.1186/s12933-014-0161-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 12/01/2014] [Indexed: 12/13/2022] Open
Abstract
Background Increasing numbers of type 2 diabetic and obese patients with enhanced rates of cardiovascular complications require surgical interventions, however they have a higher incidence of perioperative haemodynamic complications, which has been linked to adrenergic dysfunction. Therefore, we aimed to determine how α- and β-adrenoceptor (AR)-mediated haemodynamic responses are affected by isoflurane anaesthesia in experimental type 2 diabetes and obesity in vivo. Methods Sixteen-week old male Zucker type 2 Diabetic Fatty (ZDF) rats, Zucker Obese rats and their lean counterparts (n = 7-9 per group) were instrumented with radio telemeters to record blood pressure and heart rate and with vascular access ports for non-invasive intravenous drug delivery in vivo. Haemodynamic effects of α-AR (phenylephrine; 1-100 μg.kg−1) or β-AR (dobutamine; 2-120 μg.kg−1) stimulation were assessed under conscious and anaesthetised (isoflurane; 2%) conditions. Results Vascular α-AR sensitivity was increased in both diabetic (non-diabetic 80 ± 3 vs. diabetic 95 ± 4 ΔmmHg at 100 μg.kg−1; p < 0.05) and obese (lean 65 ± 6 vs. obese 84 ± 6 ΔmmHg at 20 μg.kg−1; p < 0.05) conscious rats. Interestingly, anaesthesia exacerbated and prolonged the increased α-AR function in both diabetic and obese animals (non-diabetic 51 ± 1 vs. diabetic 68 ± 4 ΔmmHg, lean 61 ± 5 vs. obese 84 ± 2 ΔmmHg at 20 μg.kg−1; p < 0.05). Meanwhile, β-AR chronotropic sensitivity was reduced in conscious diabetic and obese rats (non-diabetic 58 ± 7 vs. diabetic 27 ± 8 Δbpm, lean 103 ± 12 vs. obese 61 ± 9 Δbpm at 15 μg.kg−1; p < 0.05). Anaesthesia normalised chronotropic β-AR responses, via either a limited reduction in obese (lean 51 ± 3 vs. obese 66 ± 5 Δbpm; NS at 15 μg.kg−1) or increased responses in diabetic animals (non-diabetic 49 ± 8 vs. diabetic 63 ± 8 Δbpm, at 15 μg.kg−1; NS at 15 μg.kg−1). Conclusions Long term metabolic stress, such as during type 2 diabetes and obesity, alters α- and β-AR function, its dynamics and the interaction with isoflurane anaesthesia. During anaesthesia, enhanced α-AR sensitivity and normalised β-AR function may impair cardiovascular function in experimental type 2 diabetes and obesity.
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Affiliation(s)
- Carol T Bussey
- HeartOtago, Department of Physiology, Otago School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand.
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12
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Silva E, Natali AJ, Silva MF, Gomes GJ, Cunha DN, Ramos RM, Toledo MM, Drummond FR, Belfort FG, Novaes RD, Maldonado IR. Ventricular remodeling in growing rats with experimental diabetes: The impact of swimming training. Pathol Res Pract 2013; 209:618-26. [DOI: 10.1016/j.prp.2013.06.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/31/2013] [Accepted: 06/25/2013] [Indexed: 01/27/2023]
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The functional state of hormone-sensitive adenylyl cyclase signaling system in diabetes mellitus. JOURNAL OF SIGNAL TRANSDUCTION 2013; 2013:594213. [PMID: 24191197 PMCID: PMC3804439 DOI: 10.1155/2013/594213] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 09/05/2013] [Indexed: 12/18/2022]
Abstract
Diabetes mellitus (DM) induces a large number of diseases of the nervous, cardiovascular, and some other systems of the organism. One of the main causes of the diseases is the changes in the functional activity of hormonal signaling systems which lead to the alterations and abnormalities of the cellular processes and contribute to triggering and developing many DM complications. The key role in the control of physiological and biochemical processes belongs to the adenylyl cyclase (AC) signaling system, sensitive to biogenic amines and polypeptide hormones. The review is devoted to the changes in the GPCR-G protein-AC system in the brain, heart, skeletal muscles, liver, and the adipose tissue in experimental and human DM of the types 1 and 2 and also to the role of the changes in AC signaling in the pathogenesis and etiology of DM and its complications. It is shown that the changes of the functional state of hormone-sensitive AC system are dependent to a large extent on the type and duration of DM and in experimental DM on the model of the disease. The degree of alterations and abnormalities of AC signaling pathways correlates very well with the severity of DM and its complications.
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The role of insulin-thyroid hormone interaction on β-adrenoceptor-mediated cardiac responses. Eur J Pharmacol 2013; 718:533-43. [PMID: 23811535 DOI: 10.1016/j.ejphar.2013.06.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 06/04/2013] [Accepted: 06/16/2013] [Indexed: 02/05/2023]
Abstract
β-adrenoceptor-mediated responses are known to be attenuated in diabetic rat hearts, related to decreased receptor sensitivity and density. These impaired responses were improved with insulin in diabetic rats, but not in thyroidectomized diabetic rats. We aimed to investigate the possible interaction between insulin and thyroid hormones to restore diabetes-induced alterations on β-adrenoceptor-mediated responses. Male Sprague-Dawley rats were divided into seven groups: control (C), diabetic (D), insulin-treated diabetic (DI), thyroidectomized diabetic (TxD), insulin-treated thyroidectomized diabetic (TxDI), insulin+low dose 3,3',5-triiodo-L-thyronine (T3) treated (TxDIT2.5) or insulin+high dose T3 (TxDIT5) treated thyroidectomized diabetic rats. Diabetes was induced with 38 mg/kg streptozotocin. Cardiac function was assessed through pressure-volume analysis and papillary muscle experiments. QPCR and western blot experiments were performed to evaluate cardiac gene expressions. Hemodynamic parameters were impaired in diabetes, and were mostly corrected in DI and TxDIT5 groups. Isoprenaline- and BRL37344-induced contractile responses were also decreased in diabetes. Isoprenaline responses were improved significantly in DI and TxDIT5 groups, whereas BRL 37344-mediated responses were increased slightly. Reduced β1-adrenoceptor and SERCA 2A mRNA levels in diabetes were corrected in DI and TxDIT5 groups. Decreased SERCA 2A and increased β3-adrenoceptor protein levels in diabetes were improved in DI and TxDIT5 groups. No significant changes were found in phospholamban or endothelial nitricoxide synthase protein levels. These results show that the beneficial effects of insulin on β-adrenoceptor-mediated responses in diabetic rats are dependent upon adequate concentrations of thyroid hormones.
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A model of poorly controlled type 1 Diabetes Mellitus and its treatment with aerobic exercise training. DIABETES & METABOLISM 2013; 39:226-35. [PMID: 23522732 DOI: 10.1016/j.diabet.2013.02.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 01/31/2013] [Accepted: 02/04/2013] [Indexed: 10/27/2022]
Abstract
BACKGROUND Modern exogenous insulin therapy can improve the quality of life of Type 1 Diabetic Mellitus (T1DM) patients, although maintenance of normal glycaemic levels is often a challenge given the variety of factors that alter it. A number of studies have examined the effect of exercise in T1DM; however, the majority of experimental studies have utilized diabetic rodents with severe hyperglycaemia. Given that T1DM patients are likely to refrain from hyperglycaemia, studies examining the effects of regular exercise in which blood glucose is poorly controlled would better represent the T1DM population. METHODS The current study examined the ability of a ten-week aerobic exercise training program to modify markers of cardiovascular function and bone health in STZ-induced diabetic rodents maintained in the 9-15 mM glycaemic range through insulin therapy. RESULTS Moderate hyperglycaemia, when prolonged, leads to significant changes in cardiac structure, bone health, and glucose handling capacity. Ten weeks of exercise was able to alleviate many of these deleterious events as no significant cardiovascular functional alterations were evident except a reduction in resting heart rate and an increase in stroke volume index. Further, despite changes in cardiac dimensions, exercise was able to elevate cardiac output index and increase the E/A ratio of exercising diabetic animals which would be indicative of improvements of cardiac function. CONCLUSIONS Together, this study demonstrates that despite moderate hyperglycaemia, the combined role of a ten-week exercise training program coupled with insulin therapy is able to alleviate many of the well-known complications associated with diabetes progression.
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Abstract
AbstractThe changes in hormone-regulated adenylyl cyclase (AC) signaling system implicated in control of the nervous, cardiovascular and reproductive systems may contribute to complications of diabetes mellitus (DM). We investigated the functional state of AC system in the brain, myocardium, ovary and uterus of rats with neonatal DM and examined the influence of intranasally administered insulin on the sensitivity of this system to biogenic amines and polypeptide hormones. The regulatory effects of somatostatin and 5-HT1BR-agonist 5-nonyloxytryptamine acting via Gi protein-coupled receptors were significantly decreased in DM and partially restored in insulin-treated rats. The effects of hormones, activators of AC, are changed in tissue- and receptorspecific manner, and intranasal insulin restored the effects rather close to the level in control. In insulin-treated non-diabetic rats, AC stimulating effects of isoproterenol and relaxin in the myocardium and of human chorionic gonadotropin in the ovaries were decreased, while the effects of hormones, inhibitors of AC, were increased. These data indicate that with intranasal insulin, Gi protein-mediated signaling pathways continue to gain strength. The obtained data on the influence of hormones on AC system in the brain, myocardium, ovary and uterus allow looking anew into the mechanisms of therapeutic effects of intranasal insulin.
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Exercise increases insulin content and basal secretion in pancreatic islets in type 1 diabetic mice. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:481427. [PMID: 21912535 PMCID: PMC3170797 DOI: 10.1155/2011/481427] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 05/17/2011] [Indexed: 11/28/2022]
Abstract
Exercise appears to improve glycemic control for people with type 1 diabetes (T1D). However, the mechanism responsible for this improvement is unknown. We hypothesized that exercise has a direct effect on the insulin-producing islets. Eight-week-old mice were divided into four groups: sedentary diabetic, exercised diabetic, sedentary control, and exercised control. The exercised groups participated in voluntary wheel running for 6 weeks. When compared to the control groups, the islet density, islet diameter, and β-cell proportion per islet were significantly lower in both sedentary and exercised diabetic groups and these alterations were not improved with exercise. The total insulin content and insulin secretion were significantly lower in sedentary diabetics compared to controls. Exercise significantly improved insulin content and insulin secretion in islets in basal conditions. Thus, some improvements in exercise-induced glycemic control in T1D mice may be due to enhancement of insulin content and secretion in islets.
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Reduced CGP12177 binding to cardiac β-adrenoceptors in hyperglycemic high-fat-diet-fed, streptozotocin-induced diabetic rats. Nucl Med Biol 2011; 38:1059-66. [PMID: 21831645 DOI: 10.1016/j.nucmedbio.2011.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 03/31/2011] [Accepted: 04/13/2011] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Abnormal sympathetic nervous system and β-adrenoceptor (β-AR) signaling is associated with diabetes. [(3)H]CGP12177 is a nonselective β-AR antagonist that can be labeled with carbon-11 for positron emission tomography. The aim of this study was to examine the suitability of this tracer for evaluation of altered β-AR expression in diabetic rat hearts. METHODS Ex vivo biodistribution with [(3)H]CGP12177 was carried out in normal Sprague-Dawley rats for evaluation of specific binding and response to continuous β-AR stimulation by isoproterenol. In a separate group, high-fat-diet feeding imparted insulin resistance and a single intraperitoneal injection of streptozotocin (STZ) or vehicle evoked hyperglycemia (blood glucose >11 mM). [(3)H]CGP12177 biodistribution was assessed at 2 and 8 weeks post-STZ to measure β-AR binding in heart, 30 min following tracer injection. Western blotting of β-AR subtypes was completed in parallel. RESULTS Infusion of isoproterenol over 14 days did not affect cardiac binding of [(3)H]CGP12177. Approximately half of rats treated with STZ exhibited sustained hyperglycemia and progressive hypoinsulinemia. Myocardial [(3)H]CGP12177 specific binding was unchanged at 2 weeks post-STZ but significantly reduced by 30%-40% at 8 weeks in hyperglycemic but not euglycemic STZ-treated rats compared with vehicle-treated controls. Western blots supported a significant decrease in β(1)-AR in hyperglycemic rats. CONCLUSIONS Reduced cardiac [(3)H]CGP12177 specific binding in the presence of sustained hyperglycemia corresponds to a decrease in relative β(1)-AR expression. These data indirectly support the use of [(11)C]CGP12177 for assessment of cardiac dysfunction in diabetes.
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MacDonald JR, Oellermann M, Rynbeck S, Chang G, Ruggiero K, Cooper GJS, Hickey AJR. Transmural differences in respiratory capacity across the rat left ventricle in health, aging, and streptozotocin-induced diabetes mellitus: evidence that mitochondrial dysfunction begins in the subepicardium. Am J Physiol Cell Physiol 2010; 300:C246-55. [PMID: 21084644 DOI: 10.1152/ajpcell.00294.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In diabetic cardiomyopathy, ventricular dysfunction occurs in the absence of hypertension or atherosclerosis and is accompanied by altered myocardial substrate utilization and depressed mitochondrial respiration. It is not known if mitochondrial function differs across the left ventricular (LV) wall in diabetes. In the healthy heart, the inner subendocardial region demonstrates higher rates of blood flow, oxygen consumption, and ATP turnover compared with the outer subepicardial region, but published transmural respirometric measurements have not demonstrated differences. We aim to measure mitochondrial function in Wistar rat LV to determine the effects of age, streptozotocin-diabetes, and LV layer. High-resolution respirometry measured indexes of respiration in saponin-skinned fibers dissected from the LV subendocardium and subepicardium of 3-mo-old rats after 1 mo of streptozotocin-induced diabetes and 4-mo-old rats following 2 mo of diabetes. Heart rate and heartbeat duration were measured under isoflurane-anesthesia using a fetal-Doppler, and transmission electron microscopy was employed to observe ultrastructural differences. Heart rate decreased with age and diabetes, whereas heartbeat duration increased with diabetes. While there were no transmural respirational differences in young healthy rat hearts, both myocardial layers showed a respiratory depression with age (30-40%). In 1-mo diabetic rat hearts only subepicardial respiration was depressed, whereas after 2 mo diabetes, respiration in subendocardial and subepicardial layers was depressed and showed elevated leak (state 2) respiration. These data provide evidence that mitochondrial dysfunction is first detectable in the subepicardium of diabetic rat LV, whereas there are measureable changes in LV mitochondria after only 4 mo of aging.
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Affiliation(s)
- J R MacDonald
- University of Auckland, School of Biological Sciences, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand
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Lahaye SLD, Gratas-Delamarche A, Malardé L, Vincent S, Zguira MS, Morel SL, Delamarche P, Zouhal H, Carré F, Bekono FR. Intense exercise training induces adaptation in expression and responsiveness of cardiac β-adrenoceptors in diabetic rats. Cardiovasc Diabetol 2010; 9:72. [PMID: 21054861 PMCID: PMC2992048 DOI: 10.1186/1475-2840-9-72] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 11/05/2010] [Indexed: 12/03/2022] Open
Abstract
Background Informations about the effects of intense exercise training on diabetes-induced myocardial dysfunctions are lacking. We have examined the effects of intense exercise training on the cardiac function of diabetic rats, especially focusing on the Langendorff β-adrenergic responsiveness and on the β-adrenoceptors protein expression. Methods Control or Streptozotocin induced-diabetic male Wistar rats were randomly assigned to sedentary or trained groups. The training program consisted of 8 weeks running on a treadmill (10° incline, up to 25 m/min, 60 min/day) and was considered to be intense for diabetic rats. Results This intense exercise training amplified the in vivo diabetes-induced bradycardia. It had no effect on Langendorff basal cardiac contraction and relaxation performances in control and diabetic rats. In diabetic rats, it accentuated the Langendorff reduced responsiveness to β-adrenergic stimulation. It did not blunt the diabetes-induced decrease of β1-adrenoceptors protein expression, displayed a significant decrease in the β2-adrenoceptors protein expression and normalized the β3-adrenoceptors protein expression. Conclusions Intense exercise training accentuated the decrease in the myocardial responsiveness to β-adrenergic stimulation induced by diabetes. This defect stems principally from the β2-adrenoceptors protein expression reduction. Thus, these results demonstrate that intense exercise training induces specific effects on the β-adrenergic system in diabetes.
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Le Douairon Lahaye S, Rebillard A, Zguira MS, Malardé L, Saïag B, Gratas-Delamarche A, Carré F, Bekono FR. Effects of exercise training combined with insulin treatment on cardiac NOS1 signaling pathways in type 1 diabetic rats. Mol Cell Biochem 2010; 347:53-62. [PMID: 20936328 DOI: 10.1007/s11010-010-0611-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 09/28/2010] [Indexed: 10/19/2022]
Abstract
This study examined the effects of a dual treatment combining insulin treatment and exercise training on basal cardiac function and signaling pathways involving β3-AR, NOS1, and RyR2 in type 1 diabetic rats. Male Wistar rats were assigned into a diabetic group receiving no treatment (D), an insulin-treated diabetic (Ins), a trained diabetic (TD), and a trained insulin-treated diabetic (TIns) group. Control group (C) was included in order to confirm the deleterious effects of diabetes. Insulin treatment and/or treadmill exercise training were conducted for 8 weeks. Basal cardiac function was evaluated by Langendorff technique. Cardiac protein expression of β3-AR, NOS1, and RyR2 was assessed using Western blots. Diabetes induced a decrease of both basal diastolic and systolic (±dP/dt) cardiac function (P < 0.05). Moreover, diabetes was associated with an increase of β3-AR and NOS1 and a decrease of RyR2 expression (P < 0.05). Although combined treatment was not able to normalize -dP/dt, it succeeded to normalize +dP/dt of diabetic rats. Combined treatment led to an overexpression of RyR2. Effects of this combined treatment on +dP/dt and RyR2 were greater than the effects of insulin and exercise training, applied solely. Treatments, applied solely or in combination, resulted in a complete normalization of β3-AR and in a down-regulation of NOS1 because this protein expression in all treated diabetic rats became lower than control values (P < 0.01). Our study shows that unlike single treatments, dual treatment combining insulin treatment and exercise training was able to normalize basal systolic function of diabetic rats by a specific regulation of β3-AR-NOS1-RyR2 signaling pathways.
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Affiliation(s)
- Solène Le Douairon Lahaye
- Laboratory Movement Sport and Health Sciences, UFR APS, University of Rennes 2, Avenue Charles Tillon, 35044, Rennes cedex, France.
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Daniels A, van Bilsen M, Janssen BJA, Brouns AE, Cleutjens JPM, Roemen THM, Schaart G, van der Velden J, van der Vusse GJ, van Nieuwenhoven FA. Impaired cardiac functional reserve in type 2 diabetic db/db mice is associated with metabolic, but not structural, remodelling. Acta Physiol (Oxf) 2010; 200:11-22. [PMID: 20175764 DOI: 10.1111/j.1748-1716.2010.02102.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
AIM To identify the initial alterations in myocardial tissue associated with the early signs of diabetic cardiac haemodynamic dysfunction, we monitored changes in cardiac function, structural remodelling and gene expression in hearts of type 2 diabetic db/db mice. METHODS Cardiac dimensions and function were determined echocardiographically at 8, 12, 16 and 18 weeks of age. Left ventricular pressure characteristics were measured at 18 weeks under baseline conditions and upon dobutamine infusion. RESULTS The db/db mice were severely diabetic already at 8 weeks after birth, showing elevated fasting blood glucose levels and albuminuria. Nevertheless, echocardiography revealed no significant changes in cardiac function up to 18 weeks of age. At 18 weeks of age, left ventricular pressure characteristics were not significantly different at baseline between diabetic and control mice. However, dobutamine stress test revealed significantly attenuated cardiac inotropic and lusitropic responses in db/db mice. Post-mortem cardiac tissue analyses showed minor structural remodelling and no significant changes in gene expression levels of the sarcoplasmic reticulum calcium ATPase (SERCA2a) or beta1-adrenoceptor (beta1-AR). Moreover, the phosphorylation state of known contractile protein targets of protein kinase A (PKA) was not altered, indicating unaffected cardiac beta-adrenergic signalling activity in diabetic animals. By contrast, the substantially increased expression of uncoupling protein-3 (UCP3) and angiopoietin-like-4 (Angptl4), along with decreased phosphorylation of AMP-activated protein kinase (AMPK) in the diabetic heart, is indicative of marked changes in cardiac metabolism. CONCLUSION db/db mice show impaired cardiac functional reserve capacity during maximal beta-adrenergic stimulation which is associated with unfavourable changes in cardiac energy metabolism.
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Affiliation(s)
- A Daniels
- Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
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Le Douairon Lahaye S, Gratas-Delamarche A, Malardé L, Carré F, Rannou Bekono F. Huit semaines d’entraînement intense en endurance diminuent les β2-adrénocepteurs dans le cœur de rat diabétique. Sci Sports 2010. [DOI: 10.1016/j.scispo.2010.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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De Marinis YZ, Salehi A, Ward CE, Zhang Q, Abdulkader F, Bengtsson M, Braha O, Braun M, Ramracheya R, Amisten S, Habib AM, Moritoh Y, Zhang E, Reimann F, Rosengren A, Shibasaki T, Gribble F, Renström E, Seino S, Eliasson L, Rorsman P. GLP-1 inhibits and adrenaline stimulates glucagon release by differential modulation of N- and L-type Ca2+ channel-dependent exocytosis. Cell Metab 2010; 11:543-553. [PMID: 20519125 PMCID: PMC4310935 DOI: 10.1016/j.cmet.2010.04.007] [Citation(s) in RCA: 204] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 02/03/2010] [Accepted: 04/07/2010] [Indexed: 12/30/2022]
Abstract
Glucagon secretion is inhibited by glucagon-like peptide-1 (GLP-1) and stimulated by adrenaline. These opposing effects on glucagon secretion are mimicked by low (1-10 nM) and high (10 muM) concentrations of forskolin, respectively. The expression of GLP-1 receptors in alpha cells is <0.2% of that in beta cells. The GLP-1-induced suppression of glucagon secretion is PKA dependent, is glucose independent, and does not involve paracrine effects mediated by insulin or somatostatin. GLP-1 is without much effect on alpha cell electrical activity but selectively inhibits N-type Ca(2+) channels and exocytosis. Adrenaline stimulates alpha cell electrical activity, increases [Ca(2+)](i), enhances L-type Ca(2+) channel activity, and accelerates exocytosis. The stimulatory effect is partially PKA independent and reduced in Epac2-deficient islets. We propose that GLP-1 inhibits glucagon secretion by PKA-dependent inhibition of the N-type Ca(2+) channels via a small increase in intracellular cAMP ([cAMP](i)). Adrenaline stimulates L-type Ca(2+) channel-dependent exocytosis by activation of the low-affinity cAMP sensor Epac2 via a large increase in [cAMP](i).
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Affiliation(s)
- Yang Z De Marinis
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Albert Salehi
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Caroline E Ward
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Fernando Abdulkader
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, 05508-00 São Paulo, Brazil
| | - Martin Bengtsson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Orit Braha
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Matthias Braun
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Reshma Ramracheya
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Stefan Amisten
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Abdella M Habib
- Cambridge Institute for Medical Research, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0XY, UK
| | - Yusuke Moritoh
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Enming Zhang
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Frank Reimann
- Cambridge Institute for Medical Research, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0XY, UK
| | - Anders Rosengren
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Tadao Shibasaki
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Fiona Gribble
- Cambridge Institute for Medical Research, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0XY, UK
| | - Erik Renström
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Susumu Seino
- Division of Cellular and Molecular Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
| | - Lena Eliasson
- Lund University Diabetes Centre, Department of Clinical Sciences, Clinical Research Centre, Lund University, SE20502 Malmö, Sweden
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
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Stølen TO, Høydal MA, Kemi OJ, Catalucci D, Ceci M, Aasum E, Larsen T, Rolim N, Condorelli G, Smith GL, Wisløff U. Interval training normalizes cardiomyocyte function, diastolic Ca2+ control, and SR Ca2+ release synchronicity in a mouse model of diabetic cardiomyopathy. Circ Res 2009; 105:527-36. [PMID: 19679837 DOI: 10.1161/circresaha.109.199810] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
RATIONALE In the present study we explored the mechanisms behind excitation-contraction (EC) coupling defects in cardiomyocytes from mice with type-2 diabetes (db/db). OBJECTIVE We determined whether 13 weeks of aerobic interval training could restore cardiomyocyte Ca(2+) cycling and EC coupling. METHODS AND RESULTS Reduced contractility in cardiomyocytes isolated from sedentary db/db was associated with increased diastolic sarcoplasmic reticulum (SR)-Ca(2+) leak, reduced synchrony of Ca(2+) release, reduced transverse (T)-tubule density, and lower peak systolic and diastolic Ca(2+) and caffeine-induced Ca(2+) release. Additionally, the rate of SR Ca(2+) ATPase-mediated Ca(2+) uptake during diastole was reduced, whereas a faster recovery from caffeine-induced Ca(2+) release indicated increased Na(+)/Ca(2+)-exchanger activity. The increased SR-Ca(2+) leak was attributed to increased Ca(2+)-calmodulin-dependent protein kinase (CaMKIIdelta) phosphorylation, supported by the normalization of SR-Ca(2+) leak on inhibition of CaMKIIdelta (AIP). Exercise training restored contractile function associated with restored SR Ca(2+) release synchronicity, T-tubule density, twitch Ca(2+) amplitude, SR Ca(2+) ATPase and Na(+)/Ca(2+)-exchanger activities, and SR-Ca(2+) leak. The latter was associated with reduced phosphorylation of cytosolic CaMKIIdelta. Despite normal contractile function and Ca(2+) handling after the training period, phospholamban was hyperphosphorylated at Serine-16. Protein kinase A inhibition (H-89) in cardiomyocytes from the exercised db/db group abolished the differences in SR-Ca(2+) load when compared with the sedentary db/db mice. EC coupling changes were observed without changes in serum insulin or glucose levels, suggesting that the exercise training-induced effects are not via normalization of the diabetic condition. CONCLUSIONS These data demonstrate that aerobic interval training almost completely restored the contractile function of the diabetic cardiomyocyte to levels close to sedentary wild type.
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Affiliation(s)
- Tomas O Stølen
- Norwegian University of Science and Technology, Department of Circulation and Medical Imaging, Olav Kyrres gt. 9, 7489 Trondheim, Norway
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Abstract
Effects and mechanisms of a single bout of physical load and of the regular exercise (training) on the carbohydrate and fat metabolism are reviewed. During exercise and in the following couple of hours sugar utilization improves, "activity functions like insulin". Proper exercise contributes to using up the fat reserves, and slimmer body, fat reduction can be maintained by the combination of exercise and diet-control. Instructions in "exercise for everybody" and particularly for both type diabetics are detailed. In prevention of cardio-metabolic pathologies the most important measure were avoiding the overweight state by rational alimentation and regular physical activity.
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Affiliation(s)
- Péter Apor
- Semmelweis Egyetem Testnevelés- és Sporttudományi Kar Budapest Czakó u. 9. 1016
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Shao CH, Wehrens XHT, Wyatt TA, Parbhu S, Rozanski GJ, Patel KP, Bidasee KR. Exercise training during diabetes attenuates cardiac ryanodine receptor dysregulation. J Appl Physiol (1985) 2009; 106:1280-92. [PMID: 19131475 DOI: 10.1152/japplphysiol.91280.2008] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The present study was undertaken to assess the effects of exercise training (ExT) initiated after the onset of diabetes on cardiac ryanodine receptor expression and function. Type 1 diabetes was induced in male Sprague-Dawley rats using streptozotocin (STZ). Three weeks after STZ injection, diabetic rats were divided into two groups. One group underwent ExT for 4 wk while the other group remained sedentary. After 7 wk of sedentary diabetes, cardiac fractional shortening, rate of rise of left ventricular pressure, and myocyte contractile velocity were reduced by 14, 36, 44%, respectively. Spontaneous Ca(2+) spark frequency increased threefold, and evoked Ca(2+) release was dyssynchronous with diastolic Ca(2+) releases. Steady-state type 2 ryanodine receptor (RyR2) protein did not change, but its response to Ca(2+) was altered. RyR2 also exhibited 1.8- and 1.5-fold increases in phosphorylation at Ser(2808) and Ser(2814). PKA activity was reduced by 75%, but CaMKII activity was increased by 50%. Four weeks of ExT initiated 3 wk after the onset of diabetes blunted decreases in cardiac fractional shortening and rate of left ventricular pressure development, increased the responsiveness of the myocardium to isoproterenol stimulation, attenuated the increase in Ca(2+) spark frequency, and minimized dyssynchronous and diastolic Ca(2+) releases. ExT also normalized the responsiveness of RyR2 to Ca(2+) activation, attenuated increases in RyR2 phosphorylation at Ser(2808) and Ser(2814), and normalized CaMKII and PKA activities. These data are the first to show that ExT during diabetes normalizes RyR2 function and Ca(2+) release from the sarcoplasmic reticulum, providing insights into mechanisms by which ExT during diabetes improves cardiac function.
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Affiliation(s)
- Chun-Hong Shao
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
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