Azelnidipine protects myocardium in hyperglycemia-induced cardiac damage

Maternal Obesity: A Focus on Maternal Interventions to Improve Health of Offspring

Maternal obesity has many implications for offspring health that persist throughout their lifespan that include obesity and cardiovascular complications. Several different factors contribute to obesity and they encompass interplay between genetics and environment. In the prenatal period, untreated obesity establishes a foundation for a myriad of symptoms and negative delivery experiences, including gestational hypertensive disorders, gestational diabetes, macrosomia, and labor complications. However, data across human and animal studies show promise that nutritional interventions and physical activity may rescue much of the adverse effects of obesity on offspring metabolic health. Further, these maternal interventions improve the health of the offspring by reducing weight gain, cardiovascular disorders, and improving glucose tolerance. Mechanisms from animal studies have also been proposed to elucidate the signaling pathways that regulate inflammation, lipid metabolism, and oxidative capacity of the tissue, ultimately providing potential specific courses of treatment. This review aims to pinpoint the risks of maternal obesity and provide plausible intervention strategies. We delve into recent research involving both animal and human studies with maternal interventions. With the increasing concerning of obesity rates witnessed in the United States, it is imperative to acknowledge the long-term effects posed on future generations and specifically modify maternal nutrition and care to mitigate these adverse outcomes.

Melatonin protects the heart and pancreas by improving glucose homeostasis, oxidative stress, inflammation and apoptosis in T2DM-induced rats

Cardiomyopathy and pancreatic injury are health issues associated with type 2 diabetes mellitus (T2DM) and are characterized by elevated oxidative stress, inflammation and apoptosis. Melatonin (MLT) is a hormone with multifunctional antioxidant activity. The protective effects of MLT on the heart and pancreas during the early development of diabetic cardiomyopathy and pancreatic injury were investigated in male Wistar rats with T2DM. MLT (10 mg/kg) was administered daily by gavage for 15 days after diabetic induction. Treatment of diabetic rats with MLT significantly normalized the levels of serum glucose, HbA1-c, and the lipid profile and improved the insulin levels and insulin resistance compared with diabetic rats, affirming its antidiabetic effect. MLT significantly prevented the development of oxidative stress and sustained the levels of glutathione and glutathione peroxidase activity in the heart and pancreas of diabetic animals, indicating its antioxidant capacity. Additionally, MLT prevented the increase in proinflammatory cytokines and expression of Bax, caspase-3 and P53. Furthermore, MLT enhanced the anti-inflammatory cytokine IL-10 and antiapoptotic protein Bcl-2. MLT controlled the levels of troponin T and creatine kinase-MB and lactate dehydrogenase activity, indicating its anti-inflammatory and antiapoptotic effects. Histological examinations confirmed the protective effects of MLT on T2DM-induced injury in the myocardium, pancreas and islets of Langerhans. In conclusion, the protective effects of melatonin on the heart and pancreas during the early development of T2DM are attributed to its antihyperglycemic, antilipidemic and antioxidant influences as well as its remarkable anti-inflammatory and antiapoptotic properties.

Hyperglycemia exacerbates ischemic stroke outcome independent of platelet glucose uptake

OBJECTIVE

Hyperglycemia is a common comorbidity for ischemic stroke and is associated with worsened neurological outcomes. Platelets are central mediators of ischemic stroke and hyperglycemia mediates platelet hyperactivity. In this study, we investigated the contribution of platelet glucose metabolism to ischemic stroke.

METHODS

Mice lacking both Glut1 and Glut3 specifically in platelets (DKO) and their littermate controls (WT) were subjected to 1-hour transient middle cerebral artery occlusion under normoglycemic and streptozotocin-induced hyperglycemic conditions after which stroke outcomes, platelet activation, and platelet-neutrophil aggregate (PNA) formation were examined.

RESULTS

Under normoglycemic conditions, DKO mice were protected from ischemic stroke with smaller brain infarct volumes and improved cerebral blood flow. In addition, DKO mice had reduced platelet activation, PNA, and cerebral neutrophil recruitment after stroke. Hyperglycemia significantly increased infarct size and cerebral Evans blue extravasation and worsened neurological outcomes and cerebral blood flow in both WT and DKO mice, abolishing the protective effect witnessed under normoglycemic conditions. Flow cytometric analysis after stroke demonstrated increased platelet activation and neutrophil trafficking to the brain, independent of platelet glucose metabolism. Finally, platelets from healthy DKO mice were unable to become procoagulant upon dual agonist stimulation. Conversely, hyperglycemia increased platelet mitochondrial reactive oxygen species production which potentiated procoagulant platelet formation in WT mice and restored procoagulant platelet formation in DKO mice.

CONCLUSION

Hyperglycemia aggravates ischemic stroke outcome independent of platelet glucose uptake. Furthermore, we demonstrated that hyperglycemia primes procoagulant platelet formation. This underlines the therapeutic potential for strategies targeting procoagulant platelet formation for the treatment of acute ischemic stroke.

Polydatin and polydatin-loaded chitosan nanoparticles attenuate diabetic cardiomyopathy in rats

Hyperglycemia is associated with impairment of heart function. The current study aimed to investigate the ameliorative effect of polydatin-loaded chitosan nanoparticles (PD-CSNPs), polydatin (PD) and metformin (MET) on diabetic cardiomyopathy in rats. Rats divided into six groups; normal-control, diabetic-control, diabetic + CSNPs (diabetic rats treated with 50 mg/kg blank chitosan nanoparticles), diabetic + PD-CSNPs (diabetic rats treated with PD-CSNPs equivalent to 50 mg/kg of polydatin), diabetic + PD (diabetic rats given 50 mg/kg polydatin), diabetic + MET (diabetic rats given 100 mg/kg metformin), orally and daily for 4 weeks. Treatment of diabetic rats with PD-CSNPs, PD and MET showed a significant reduction in the values of glucose and glycosylated hemoglobin with improvement in heart function biomarkers through decreasing serum creatine kinase and creatine kinase myocardial band activities compared to diabetic control. The treatment agents also suppressed the elevated lipid peroxidation product, increased values of glutathione content, superoxide dismutase, superoxide peroxidase, and catalase activities in the heart of diabetic treated rats. Furthermore, PD-CSNPs, PD and MET decreased heart tissue levels of a pro-inflammatory cytokine; tumor necrosis factor-alpha and nuclear factor-kappa β, upregulation of heart gene expressions; nuclear factor erythroid 2-related factor 2 and heme oxygenase-1. Histological and ultrastructural examinations revealed the ameliorative effect of PD-CSNPs, PD and MET against the harmful of diabetic cardiomyopathy by reducing the cardiac fibers, necrotic cardiac myocytes, inflammatory cell infiltration, and the arrangement of the myofibrils and intercalated discs. In conclusion, the new formula of PD-CSNPs was more effective than PD and MET in amelioration the diabetic cardiomyopathy through its antioxidant, anti-inflammatory and prolonged-release properties.

The potential effect of garlic extract and curcumin nanoparticles against complication accompanied with experimentally induced diabetes in rats

BACKGROUND

Modified herbal medicines implicate the combination of several therapeutic practices of native systems of medicine that may extend many earlier generations, which frequently afford valuable therapeutic benefits.

PURPOSE

In this study, the role of nano-curcumin and aged garlic extract (AGE) as two modified phytomedicines on alleviating both of advanced glycation end products (AGEPs) and oxidative stress (OS) in streptozotocin (STZ) induced diabetic rats were investigated during this study.

METHOD

Nano-curcumin and AGE suspension were orally administrated at a dose of 300, 500 mg/kg body weight respectively. Serum glucose, insulin, total cholesterol, triglycerides and myocardial enzyme activities including creatine kinase-isoenzyme (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) were determined biochemically, while quantitative real-time polymerase chain reaction (qRT-PCR)-test had been used to determine relative of manganese-superoxide dismutase (Mn-SOD) and receptor for advanced glycation end products (RAGE) gene expressions in the heart tissue of rats. Structure of rat's heart tissue was examined by histopathological analysis (H&E).

RESULTS

AGE increased the body weight and insulin concentration, while, it decreased serum glucose concentration, CK-MB, and LDH enzyme activities in comparing with the diabetic group. In addition, total cholesterol, triglycerides, and AST didn't show any significant changes in serum values of AGE compared to diabetic rats. Nano-curcumin suspension decreased the serum levels of triglycerides, CK- MB, LDH, and AST. While, there were non-significant changes in the body weight, glucose, insulin, and total cholesterol level of the same group compared with the STZ- untreated induced diabetic rats. The transcript quantity of manganese-superoxide dismutase gene (Mn-SOD) was highly accumulated (3.25 and 3.87-fold) in the heart tissue sample of the induced diabetic rats in response to both nano-Curcumin and AGE suspension respectively. While AGE was the most potent treatment where it caused down regulation of the receptor for advanced glycation end products gene (RAGE) expression (1.79-fold). Results of histopathological analyses under the light microscope showed restoring the structural integrity of the myocytes towards normalization in diabetic hearts treated with each of nano-curcumin and AGE suspension compared with the untreated diabetic heart samples.

CONCLUSION

Nano-curcumin and AGE suspension have a great therapeutic potential in the treatment of DCM, Diabetic cardiomyopathy, by attenuating cardiac inflammation, myocardial fibrosis, and programmed myocardial cell deaths through inhibiting OS and AGEPs accumulation in diabetic heart tissue. Furthermore, the hypoglycemic antioxidant properties of AGE resulted in more potent therapeutic effect than nano-curcumin in the treatment of diabetic hearts.

Limonin alleviates macro- and micro-vascular complications of metabolic syndrome in rats: A comparative study with azelnidipine

BACKGROUND

Hypertension is a serious component of metabolic syndrome (MetS).

HYPOTHESIS

This research investigates the potential protective effect of limonin against MetS-associated hypertension in comparison with azelnidipine, a common calcium channel blocker.

STUDY DESIGN

MetS was induced in rats by 10% fructose in water and 3% salt in diet over a 16-week period. Limonin (50 mg/kg) and azelnidipine (5 mg/kg) were administered daily in the last four weeks METHODS: Non-invasive blood pressure (BP) was recorded in conscious animals. Concentration-response curves for phenylephrine (PE) and acetylcholine (ACh) were analysed in thoracic aorta (macrovessels) and kidney microvessels. Blood glucose level, serum insulin level, advanced glycation end products (AGEs), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA) and transforming growth factor-β1 (TGF-β1) were determined.

RESULTS

Limonin alleviated elevations in systolic and diastolic BP associated with MetS similar to levels associated with azelnidipine. Limonin prevented the MetS induced exaggerated macro- and micro-vascular contractility to PE and the impaired dilatation to ACh. However, in vitro incubation with limonin partially alleviated the deteriorated vascular reactivity of aorta isolated from MetS animals or AGEs injured aorta. Limonin did not have direct relaxant effect on the isolated vessel. On the other hand, limonin reduced the elevated serum levels of AGEs, TNF-α and MDA. Limonin suppressed the vascular fibrosis through reducing the elevated serum level of TGF-β1 and excessive aortic collagen deposition. Limonin decreased the elevated HOMA-IR in MetS animals.

CONCLUSION

Limonin offsets the hypertensive and vascular impairment associated with MetS via attenuation of inflammation and fibrosis. Its impact is comparable to that of azelnidipine.

The Antioxidant Potential of Azadirachta indica Ameliorates Cardioprotection Following Diabetic Mellitus-Induced Microangiopathy

BACKGROUND

Cardiac complications associated with diabetes mellitus have become major cause of concern. Antidiabetic drugs, with varied mode of action, are although available, apprehensions exist for their limited action or side effects upon prolonged use. Efforts are therefore inclined toward finding other alternatives. The present study was, thus, undertaken to evaluate the cardioprotective effect of Azadirachta indica (AI) on microangiopathic changes in rat model of diabetes.

MATERIALS AND METHODS

Diabetes was induced in male rats by single intraperitoneal injection of streptozotocin (60 mg/kg body weight). Seven days after glucose levels are stabilized, aqueous leaf extract of AI (ALE) (600 mg/kg(1) body weight) was administered orally to diabetic animals every day for 7 days.

RESULTS

High blood glucose characterizing diabetes in these animals was found to show increased lipid peroxidation (LPO), altered antioxidant biomarkers together with microangiopathic alterations. The treatment of diabetic rats with ALE reduced the levels of blood glucose, LPO, and restored the activities of antioxidant enzyme. Light and transmission electron microscopic analysis revealed reduced necrotic areas and inflammation in tissue architecture of ALE treated heart in comparison to untreated diabetic group.

CONCLUSION

AI provides cardioprotection by ameliorating oxidative stress in rat model of diabetic mellitus.

SUMMARY

The streptozotocin (STZ) treatment (60 mg/kg body weight) to animals induced diabetic changes such as elevated blood glucose levels, decreased body weight, altered lipid profiles together with development of proxidant state evidenced by elevated levels of lipid peroxidation (LPO), depletion in reduced glutathione (GSH) levels and altered antioxidant enzymes with consequent microangiopathic alterations in heart tissue evinced by localization of necrotic and inflamed areas in heart tissueThe treatment of animals with Azadirachta indica leaf extract (ALE) (600 mg/kg body weight) post-STZ treatment significantly reversed the adverse effects witnessed by normalized blood glucose levels, improvement in reduced body weight and stabilized lipid profilesFurther, ALE treatment also significantly reduced the LPO indices, improvement in GSH content and restoration of antioxidant enzyme activities, suggesting antioxidatant potential of ALEThe microangiopathic changes in the heart tissue consequent to induction of diabetes and oxidative stress by STZ as reiterated through light microscopy and transmission electron microscopy were found to be reversed by ALE treatment. These observations pointed toward cardiopreventive effects of ALE following microangiopathic changes as seen following induction of diabetes mellitus. Abbreviations used: AI: Azadirachta indica, ALE: Azadirachta indica Leaves Extract. STZ: Streptozotocin, LPO Lipid per oxidation, GSH: Glutathione, GSSG: Glutathione disulphide, SOD: Superoxide dismutase, GP: Glutathione peroxidase, GR: Glutathione reductase.

Oleuropein offers cardioprotection in rats with simultaneous type 2 diabetes and renal hypertension

Objectives:

The study aimed at examining the role of oxidative stress in cadioprotective effects of oleuropein in a rat model of simultaneous type 2 diabetes and renal hypertension.

Materials and Methods:

Five groups of male Sprague-Dawley rats including a control group, a diabetic-hypertensive group receiving vehicle, and three diabetic-hypertensive groups receiving oleuropein at 20, 40, or 60 mg/kg/day were used. Blood pressure and glucose, serum malondialdehyde, and erythrocyte superoxide dismutase were measured, and animal's hearts with ischemia/reperfusion injuries were used using Langendorff technique.

Results:

Blood pressure, blood glucose, serum malondialdehyde, infarct size, coronary effluent creatine kinase-MB, and coronary resistance of diabetic-hypertensive group were significantly higher than those of the control group, while those of the oleuropein-receiving groups were significantly lower than those of the diabetic hypertensive group receiving the vehicle. Erythrocyte superoxide dismutase, left ventricular developed pressure, and rate of rise and rate of decrease of ventricular pressure of diabetic-hypertensive group were significantly lower than those of the control group. These parameters as well as heart rate of oleuropein-receiving groups were significantly higher than those of the diabetic-hypertensive group.

Conclusion:

The findings indicate that oleuropein offered cardioprotection, which might be partly mediated by its antioxidant properties.

Hydroalcoholic extract of Allium eriophyllum leaves attenuates cardiac impairment in rats with simultaneous type 2 diabetes and renal hypertension

Some species of Allium family have been shown to offer cardioprotection in animal studies. This study aimed at examining possible role of oxidative stress in the cardioprotective effects of hydroalcoholic extract of Allium eriophyllum in rats with simultaneous type 2 diabetes and renal hypertension. Six groups of male Spargue-Dawley rats (8-10 rats each) including a sham-control, a diabetic group, a renal hypertensive group, three groups of animals with simultaneous diabetes and hypertension receiving vehicle, or the extract at 30 or 100 mg/kg/day were used. Four weeks after receiving vehicle or extract, blood pressure, fasting blood glucose, and serum superoxide dismutase and glutathione reductase levels were measured, and isolated heart studies were performed. Systolic blood pressure, fasting blood glucose, coronary effluent creatine kinase-MB, infarct size and coronary resistance of diabetic hypertensive group receiving vehicle were significantly higher than those of the sham-control group and treatment with the extract prevented the increase of these variables. Moreover, rate of rise and decrease of left ventricular pressure, left ventricular developed pressure, rate pressure product and serum levels of superoxide dismutase and glutathione reductase of diabetic hypertensive group receiving vehicle were significantly lower than those the sham-control group, and treatment with the extract prevented the decrease of these variables. The findings indicate that hydroalcoholic extract of A. eriophyllum leaves, possibly by an antioxidant mechanism, protected against simultaneous diabetes and hypertension-induced cardiac dysfunction.

A novel role for SIRT-1 in L-arginine protection against STZ induced myocardial fibrosis in rats

BACKGROUND

L-arginine (L-ARG) effectively protects against diabetic impediments. In addition, silent information regulator (SIRT-1) activators are emerging as a new clinical concept in treating diabetic complications. Accordingly, this study aimed at delineating a role for SIRT-1 in mediating L-ARG protection against streptozotocin (STZ) induced myocardial fibrosis.

METHODS

Male Wistar rats were allocated into five groups; (i) normal control rats received 0.1 M sodium citrate buffer (pH 4.5); (ii) STZ at the dose of 60 mg/kg dissolved in 0.1 M sodium citrate buffer (pH 4.5); (iii) STZ + sirtinol (Stnl; specific inhibitor of SIRT-1; 2 mg/Kg, i.p.); (iv) STZ + L-ARG given in drinking water (2.25%) or (v) STZ + L-ARG + Stnl.

RESULTS

L-ARG increased myocardial SIRT-1 expression as well as its protein content. The former finding was paralleled by L-ARG induced reduction in myocardial fibrotic area compared to STZ animals evidenced histopathologically. The reduction in the fibrotic area was accompanied by a decline in fibrotic markers as evident by a decrease in expression of collagen-1 along with reductions in myocardial TGF-β, fibronectin, CTGF and BNP expression together with a decrease in TGF-β and hydroxyproline contents. Moreover, L-ARG increased MMP-2 expression in addition to its protein content while decreasing expression of PAI-1. Finally, L-ARG protected against myocardial cellular death by reduction in NFκ-B mRNA as well as TNF-α level in association with decline in Casp-3 and FAS expressions andCasp-3protein content in addition to reduction of FAS positive cells. However, co-administration of L-ARG and Stnl diminished the protective effect of L-ARG against STZ induced myocardial fibrosis.

CONCLUSION

Collectively, these findings associate a role for SIRT-1 in L-ARG defense against diabetic cardiac fibrosis via equilibrating the balance between profibrotic and antifibrotic mediators.

Evaluation of buspirone on streptozotocin induced type 1 diabetes and its associated complications

We have evaluated the effect of buspirone (1.5 mg/kg/day, p.o.) type 1 diabetes induced cardiovascular complications induced by streptozotocin (STZ, 45 mg/kg, i.v.) in Wistar rats. Various biochemical, cardiovascular, and hemodynamic parameters were measured at the end of 8 weeks of treatment. STZ produced significant hyperglycaemia, hypoinsulinemia, and dyslipidemia, which was prevented by buspirone treatment. STZ produced increase in serum creatinine, urea, lactate dehydrogenase, creatinine kinase, and C-reactive protein levels and treatment with buspirone produced reduction in these levels. STZ produced increase in cardiac and LV hypertrophy index, LV/RV ratio, and LV collagen, which were decreased by buspirone treatment. Buspirone also prevented STZ induced hemodynamic alterations and oxidative stress. These results were further supported by histopathological studies in which buspirone showed marked reduction in fibrosis and cardiac fiber disarray. In conclusion, our data suggests that buspirone is beneficial as an antidiabetic agent in type 1 diabetes mellitus and also prevents its cardiac complications.

Effects of Short-term Renovascular Hypertension and Type 2 Diabetes on Cardiac Functions in Rats

BACKGROUND

The cardiac effects simultaneously occurring during experimental hypertension and diabetes have rarely been investigated. This study aimed at examining the effects of short-term renovascular hypertension and type 2 diabetes on cardiac functions.

METHODS

Five groups (7 each) of male Sprague-Dawley rats, including a control group, a diabetes (induced by Streptozocin and Nicotinamide) group, a renovascular hypertensive (induced by placing Plexiglas clips on the left renal arteries) group, a sham group, and a simultaneously hypertensive-diabetic group, were used. The animals' hearts were used for isolated heart studies, and the indices of cardiac functions and coronary effluent creatine kinase MB were measured. The results were analyzed using One-way Analysis of Variance, followed by the Duncan Multiple Range test.

RESULTS

The diabetic group had a significantly lower rate of rise (-29.5%) and decrease (-36.18%) in ventricular pressure, left ventricular developed pressure (-28.8%), and rate pressure product (-35%), and significantly higher creatine kinase MB (+166%) and infarct size (+36.2%) than those of the control group. The hypertensive group had a significantly higher rate of rise (+12.17%) and decrease (+16.2%) in ventricular pressure, left ventricular developed pressure (+16%), and rate pressure product (+24%), and significantly lower creatine kinase MB (-30%) and infarct size (-27%) than those of the sham group. Simultaneously, the diabetic and hypertensive rats had a significantly higher rate of rise (+32%) and decrease (+30.2%) in ventricular pressure, left ventricular developed pressure (+17.2%), and rate pressure product (+22.2%), and significantly lower creatine kinase MB (-24%) and infarct size (-16.2%) than those of the diabetic group.

CONCLUSION

The findings indicated that the simultaneity of hypertension with type 2 diabetes attenuated diabetes-induced cardiac impairment.

Effect of light exposure on metalloporphyrin-treated newborn mice

BACKGROUND

Neonatal hyperbilirubinemia arises from increased bilirubin production and decreased bilirubin elimination. Although phototherapy safely and effectively reduces bilirubin levels, recent evidence shows that it has adverse effects. Therefore, alternative treatments are warranted. Metalloporphyrins, competitive inhibitors of heme oxygenase (HO), the rate-limiting enzyme in bilirubin production, effectively reduce bilirubin formation; however, many are photoreactive. Here, we investigated possible photosensitizing effects of chromium mesoporphyrin (CrMP) and zinc deuteroporphyrin bis-glycol (ZnBG).

METHODS AND RESULTS

Administration of CrMP or ZnBG to 3-d-old mouse pups (3.75-30.0 μmol/kg intraperitoneally) and exposure to cool white (F20T12CW) and blue (TL20W/52) fluorescent lights (+L) for 3 h, resulted in a dose-dependent mortality (50% lethal dose (LD50) = 21.5 and 19.5 μmol/kg, respectively). In contrast to ZnBG, there was no significant difference in survival between the CrMP+L and CrMP groups. Following 30 μmol/kg ZnBG+L, we found significant weight loss, decreased liver antioxidant capacities, and increased aspartate aminotransaminase levels. At 6-d post-light exposure, ZnBG+L-treated pups showed gross and histologic skin changes at doses >7.5 μmol/kg. No lethality was observed following treatment with 30 μmol ZnBG/kg plus exposure to blue light-emitting diodes. Phototoxicity of ZnBG was dependent on light source, emission spectrum, and irradiance.

CONCLUSION

Low doses of ZnBG (<3.75 μmol/kg) retained maximal HO inhibitory potency without photosensitizing effects, and therefore are potentially useful in treating neonatal hyperbilirubinemia.

Cardiac fibrosis and dysfunction in experimental diabetic cardiomyopathy are ameliorated by alpha-lipoic acid

Background

Alpha-lipoic acid (ALA), a naturally occurring compound, exerts powerful protective effects in various cardiovascular disease models. However, its role in protecting against diabetic cardiomyopathy (DCM) has not been elucidated. In this study, we have investigated the effects of ALA on cardiac dysfunction, mitochondrial oxidative stress (MOS), extracellular matrix (ECM) remodeling and interrelated signaling pathways in a diabetic rat model.

Methods

Diabetes was induced in rats by I.V. injection of streptozotocin (STZ) at 45 mg/kg. The animals were randomly divided into 4 groups: normal groups with or without ALA treatment, and diabetes groups with or without ALA treatment. All studies were carried out 11 weeks after induction of diabetes. Cardiac catheterization was performed to evaluate cardiac function. Mitochondrial oxidative biochemical parameters were measured by spectophotometeric assays. Extracellular matrix content (total collagen, type I and III collagen) was assessed by staining with Sirius Red. Gelatinolytic activity of Pro- and active matrix metalloproteinase-2 (MMP-2) levels were analyzed by a zymogram. Cardiac fibroblasts differentiation to myofibroblasts was evaluated by Western blot measuring smooth muscle actin (α-SMA) and transforming growth factor–β (TGF-β). Key components of underlying signaling pathways including the phosphorylation of c-Jun N-terminal kinase (JNK), p38 MAPK and ERK were also assayed by Western blot.

Results

DCM was successfully induced by the injection of STZ as evidenced by abnormal heart mass and cardiac function, as well as the imbalance of ECM homeostasis. After administration of ALA, left ventricular dysfunction greatly improved; interstitial fibrosis also notably ameliorated indicated by decreased collagen deposition, ECM synthesis as well as enhanced ECM degradation. To further assess the underlying mechanism of improved DCM by ALA, redox status and cardiac remodeling associated signaling pathway components were evaluated. It was shown that redox homeostasis was disturbed and MAPK signaling pathway components activated in STZ-induced DCM animals. While ALA treatment favorably shifted redox homeostasis and suppressed JNK and p38 MAPK activation.

Conclusions

These results, coupled with the excellent safety and tolerability profile of ALA in humans, demonstrate that ALA may have therapeutic potential in the treatment of DCM by attenuating MOS, ECM remodeling and JNK, p38 MAPK activation.

Alteration of purinergic neurotransmission in isolated atria of streptozotocin-induced diabetic rats

Cardiac dysfunctions are described in diabetes. However, the role of purinergic neurotransmission in diabetes-related cardiovascular diseases is unknown. The purpose of this study was to evaluate the purinergic neurotransmission in isolated atria from streptozotocin-induced diabetic rats. The animals were grouped as control and diabetic with 30 days (D30) and 60 days (D60) after streptozotocin-induced diabetes. The isolated left and right atria were used in functional experiments. The effects of adenosine triphosphate, uridine diphosphate, and adenosine were evaluated on atrial inotropism and chronotropism. The antagonists 8-cyclopentyl-1,3-dipropylxanthine and pyridoxal-phosphate-6-azophenyl-2',4'-disulfonate were also used, as blockers of P1 and P2 receptors, respectively. A negative inotropic effect followed by a positive inotropic effect was induced by adenosine triphosphate in isolated atria. This negative inotropic effect was decreased by 25% in left atria of D30. Additionally, the apparent affinity for adenosine was diminished in left atria of D30, suggesting changes in P1 receptor function. No changes were found in the right atria of D30 stimulated by adenosine. The left atria and right atria stimulated by uridine diphosphate showed an increased inotropic effect of 92% and 17%, respectively. No changes were observed in left and right atria of D30 stimulated by uridine diphosphate. Our data showed the involvement of purinergic neurotransmission in diabetes-related cardiovascular changes.

High glucose-induced Ca2+ overload and oxidative stress contribute to apoptosis of cardiac cells through mitochondrial dependent and independent pathways

BACKGROUND

Cardiac cell apoptosis is the initiating factor of cardiac complications especially diabetic cardiomyopathy. Mitochondria are susceptible to the damaging effects of elevated glucose condition. Calcium overload and oxidative insult are the two mutually non-exclusive phenomena suggested to cause cardiac dysfunction. Here, we examined the effect of high-glucose induced calcium overload in calpain-1 mediated cardiac apoptosis in an in vitro setting.

METHODS

H9c2, rat ventricular myoblast cell line was treated with elevated glucose condition and the cellular consequences were studied. Intracellular calcium trafficking, ROS generation, calpain-1 activation and caspase-12 and caspase-9 pathway were studied using flow cytometry, confocal microscopy and Western blot analysis.

RESULTS

High-glucose treatment resulted in increased intracellular calcium ([Ca2+]i) which was mobilized to the mitochondria. Concomitant intra-mitochondrial calcium ([Ca2+]m) increase resulted in enhanced reactive oxygen and nitrogen species generation. These events led to mitochondrial dysfunction and apoptosis. Cardiomyocyte death exhibited several classical markers of apoptosis, including activation of caspases, appearance of annexin V on the outer plasma membrane, increased population of cells with sub-G0/G1 DNA content and nuclear condensation. Key findings include elucidation of cell signaling mechanism of high-glucose induced calcium-dependent cysteine protease calpain-1 activation, which triggers non-conventional caspases as alternate mode of cell death.

CONCLUSION

This information increases the understanding of cardiac cell death under hyperglycemic condition and can possibly be extended for designing new therapeutic strategies for diabetic cardiomyopathy.

GENERAL SIGNIFICANCE

The novel findings of the study reveal that high glucose induces apoptosis by both mitochondria-dependent and independent pathways via concomitant rise in intracellular calcium.

Taurine exerts hypoglycemic effect in alloxan-induced diabetic rats, improves insulin-mediated glucose transport signaling pathway in heart and ameliorates cardiac oxidative stress and apoptosis

Hyperlipidemia, inflammation and altered antioxidant profiles are the usual complications in diabetes mellitus. In the present study, we investigated the therapeutic potential of taurine in diabetes associated cardiac complications using a rat model. Rats were made diabetic by alloxan (ALX) (single i.p. dose of 120mg/kg body weight) and left untreated or treated with taurine (1% w/v, orally, in water) for three weeks either from the day of ALX exposure or after the onset of diabetes. Animals were euthanized after three weeks. ALX-induced diabetes decreased body weight, increased glucose level, decreased insulin content, enhanced the levels of cardiac damage markers and altered lipid profile in the plasma. Moreover, it increased oxidative stress (decreased antioxidant enzyme activities and GSH/GSSG ratio, increased xanthine oxidase enzyme activity, lipid peroxidation, protein carbonylation and ROS generation) and enhanced the proinflammatory cytokines levels, activity of myeloperoxidase and nuclear translocation of NFκB in the cardiac tissue of the experimental animals. Taurine treatment could, however, result to a decrease in the elevated blood glucose and proinflammatory cytokine levels, diabetes-evoked oxidative stress, lipid profiles and NFκB translocation. In addition, taurine increased GLUT 4 translocation to the cardiac membrane by enhanced phosphorylation of IR and IRS1 at tyrosine and Akt at serine residue in the heart. Results also suggest that taurine could protect cardiac tissue from ALX induced apoptosis via the regulation of Bcl2 family and caspase 9/3 proteins. Taken together, taurine supplementation in regular diet could play a beneficial role in regulating diabetes and its associated complications in the heart.

Azelnidipine prevents cardiac dysfunction in streptozotocin-diabetic rats by reducing intracellular calcium accumulation, oxidative stress and apoptosis

BACKGROUND

Numerous evidences suggest that diabetic heart is characterized by compromised ventricular contraction and prolonged relaxation attributable to multiple causative factors including calcium accumulation, oxidative stress and apoptosis. Therapeutic interventions to prevent calcium accumulation and oxidative stress could be therefore helpful in improving the cardiac function under diabetic condition.

METHODS

This study was designed to examine the effect of long-acting calcium channel blocker (CCB), Azelnidipine (AZL) on contractile dysfunction, intracellular calcium (Ca2+) cycling proteins, stress-activated signaling molecules and apoptosis on cardiomyocytes in diabetes. Adult male Wistar rats were made diabetic by a single intraperitoneal (IP) injection of streptozotocin (STZ). Contractile functions were traced from live diabetic rats to isolated individual cardiomyocytes including peak shortening (PS), time-to-PS (TPS), time-to-relengthening (TR90), maximal velocity of shortening/relengthening (± dL/dt) and intracellular Ca2+ fluorescence.

RESULTS

Diabetic heart showed significantly depressed PS, ± dL/dt, prolonged TPS, TR90 and intracellular Ca2+ clearing and showed an elevated resting intracellular Ca2+. AZL itself exhibited little effect on myocyte mechanics but it significantly alleviated STZ-induced myocyte contractile dysfunction. Diabetes increased the levels of superoxide, enhanced expression of the cardiac damage markers like troponin I, p67phox NADPH oxidase subunit, restored the levels of the mitochondrial superoxide dismutase (Mn-SOD), calcium regulatory proteins RyR2 and SERCA2a, and suppressed the levels of the anti-apoptotic Bcl-2 protein. All of these STZ-induced alterations were reconciled by AZL treatment.

CONCLUSION

Collectively, the data suggest beneficial effect of AZL in diabetic cardiomyopathy via altering intracellular Ca2+ handling proteins and preventing apoptosis by its antioxidant property.

Effects of calcium channel blockers on glucose tolerance, inflammatory state, and circulating progenitor cells in non-diabetic patients with essential hypertension: a comparative study between azelnidipine and amlodipine on glucose tolerance and endothelial function--a crossover trial (AGENT)

BACKGROUND

Hypertension is associated with impaired glucose tolerance and insulin resistance. Medical treatment that interferes with various steps in the renin-angiotensin system improves glucose tolerance and insulin resistance. However, it remains unclear if long-acting calcium channel blockers (CCBs) such as azelnidipine and amlodipine affect glucose tolerance and insulin resistance in clinical practice.

METHODS

Seventeen non-diabetic patients with essential hypertension who had controlled blood pressure levels using amlodipine (5 mg/day) were enrolled in this study. After randomization, either azelnidipine (16 mg/day) or amlodipine (5 mg/day) was administered in a crossover design for 12-weeks. At baseline and the end of each CCB therapy, samples of blood and urine were collected and 75 g oral glucose tolerance test (OGTT) was performed. In addition, hematopoietic progenitor cells (HPCs) were measured at each point by flow cytometry and endothelial functions were measured by fingertip pulse amplitude tonometry using EndoPAT.

RESULTS

Although blood pressure levels were identical after each CCB treatment, the heart rate significantly decreased after azelnidipine administration than that after amlodipine administration (P < 0.005). Compared with amlodipine administration, azelnidipine significantly decreased levels of glucose and insulin 120 min after the 75 g OGTT (both P < 0.05). Serum levels of high-sensitivity C-reactive protein (P = 0.067) and interleukin-6 (P = 0.035) were decreased. Although endothelial functions were not different between the two medication groups, the number of circulating HPCs was significantly increased after azelnidipine administration (P = 0.016).

CONCLUSIONS

These results suggest that azelnidipine treatment may have beneficial effects on glucose tolerance, insulin sensitivity, the inflammatory state, and number of circulating progenitor cells in non-diabetic patients with essential hypertension.