Mesenchymal stem cell-derived exosomes increase ATP levels,decrease oxidative stress and activate PI3K/Akt pathway to enhance myocardial viability and prevent adverse remodeling after myocardial ischemia/reperfusion injury

We have previously identified exosomes as the paracrine factor secreted by mesenchymal stem cells. Recently, we found that the key features of reperfusion injury, namely loss of ATP/NADH, increased oxidative stress and cell death were underpinned by proteomic deficiencies in ischemic/reperfused myocardium, and could be ameliorated by proteins in exosomes. To test this hypothesis in vivo, mice (C57Bl6/J) underwent 30 min ischemia, followed by reperfusion (I/R injury). Purified exosomes or saline was administered 5 min before reperfusion. Exosomes reduced infarct size by 45% compared to saline treatment. Langendorff experiments revealed that intact but not lysed exosomes enhanced viability of the ischemic/reperfused myocardium. Exosome treated animals exhibited significant preservation of left ventricular geometry and contractile performance during 28 days follow-up. Within an hour after reperfusion, exosome treatment increased levels of ATP and NADH, decreased oxidative stress, increased phosphorylated-Akt and phosphorylated-GSK-3β, and reduced phosphorylated-c-JNK in ischemic/reperfused hearts. Subsequently, both local and systemic inflammation were significantly reduced 24 h after reperfusion. In conclusion, our study shows that intact exosomes restore bioenergetics, reduce oxidative stress and activate pro-survival signaling, thereby enhancing cardiac function and geometry after myocardial I/R injury. Hence, mesenchymal stem cell-derived exosomes are a potential adjuvant to reperfusion therapy for myocardial infarction.     

Efficacy of olmesartan and nifedipine on recurrent hypoxia-induced left ventricular remodeling in diabetic mice

AimsRecurrent hypoxia due to sleep apnea syndrome is implicated in cardiovascular events, especially in diabetic patients, but the underlying mechanisms remain controversial. We previously reported that angiotensin II receptor blockers can improve hypoxia-induced left ventricular remodeling. The aim of this study was to examine the effect on left ventricular remodeling of adding a calcium channel blocker to angiotensin II receptor blocker therapy in diabetic mice exposed to recurrent hypoxia.Main methodsMale db/db mice (8-week-old) and age-matched control db/+ mice were fed a Western diet and subjected to recurrent hypoxia (oxygen at 10 ± 0.5% for 8 h daily during the daytime) or normoxia for 3 weeks. Hypoxic db/db mice were treated with the vehicle, olmesartan (3 mg/kg/day), nifedipine (10 mg/kg/day), or both drugs.Key findingsRecurrent hypoxia caused hypertrophy of cardiomyocytes, interstitial fibrosis, and a significant increase in expression of the oxidative stress marker 4-hydroxy-2-nonenal (4-HNE) in the left ventricular myocardium. Treatment with olmesartan, nifedipine, or both drugs had no effect on systolic blood pressure, and each treatment achieved similar suppression of 4-HNE expression. Olmesartan and the combination with olmesartan and nifedipine significantly prevented cardiomyocyte hypertrophy more than treatment with nifedipine alone. On the other hand, olmesartan combined with nifedipine significantly reduced cytokine expression, superoxide production and matrix metalloproteinase (MMP)-9 activity, and significantly suppressed interstitial fibrosis in the left ventricular myocardium.SignificanceThe combination with olmesartan and nifedipine, as well as a monotherapy with olmesartan, exerts preferable cardioprotection in diabetic mice exposed to recurrent hypoxia.     

TNF-α inhibitor protects against myocardial ischemia/reperfusion injury via Notch1-mediated suppression of oxidative/nitrative stress

TNF-α inhibitor reportedly protects against myocardial ischemia/reperfusion (MI/R) injury. It can also increase Notch1 expression in inflammatory bowel disease, revealing the regulation of Notch1 signaling by TNF-α inhibitor. However, the interaction between TNF-α inhibitor and Notch1 signaling in MI/R remains unclear. This study aimed to determine the involvement of TNF-α inhibitor with Notch1 in MI/R and delineate the related mechanism. Notch1-specific small interfering RNA (20 μg) or Jagged1 (a Notch ligand, 12 μg) was delivered through intramyocardial injection. Forty-eight hours after injection, mice received 30 min of myocardial ischemia followed by 3 h (for cell apoptosis and oxidative/nitrative stress) or 24 h (for infarct size and cardiac function) of reperfusion. Ten minutes before reperfusion, mice randomly received an intraperitoneal injection of vehicle, etanercept, diphenyleneiodonium, 1400W, or EUK134. Finally, downregulation of Notch1 significantly reversed the alleviation of MI/R injury induced by etanercept, as evidenced by enlarged myocardial infarct size, suppressed cardiac function, and increased myocardial apoptosis. Moreover, Notch1 blockade increased the expression of inducible NO synthase (iNOS) and gp^91phox, enhanced NO and superoxide production, and accelerated their cytotoxic reaction product, peroxynitrite. Furthermore, NADPH inhibition with diphenyleneiodonium or iNOS suppression with 1400W mitigated the aggravation of MI/R injury induced by Notch1 downregulation in mice treated with etanercept. Additionally, either Notch1 activation with Jagged1 or peroxynitrite decomposition with EUK134 reduced nitrotyrosine content and attenuated MI/R injury. These data indicate that MI/R injury can be attenuated by TNF-α inhibitor, partly via Notch1 signaling-mediated suppression of oxidative/nitrative stress.     

Cardioprotective effects of lipoic acid,quercetin and resveratrol on oxidative stress related to thyroid hormone alterations in long-term obesity

This study investigated possible mechanisms for cardioprotective effects of lipoic acid (LA), quercetin (Q) and resveratrol (R) on oxidative stress related to thyroid hormone alterations in long-term obesity. Female C57BL/6 mice were fed on high-fat diet (HFD), HFD + LA, HFD + R, HFD + Q and normal diet for 26 weeks. Body weight, blood pressure, thyroid hormones, oxidative stress markers, angiotensin converting enzyme (ACE), nitric oxide synthase (NOS) and ion pump activities were measured, and expression of cardiac genes was analyzed by real-time polymerase chain reaction. HFD induced marked increase (P < .05) in body weight, blood pressure and oxidative stress, while plasma triidothyronine levels reduced. ACE activity increased (P < .05) in HFD mice (0.69 ± 0.225 U/mg protein) compared with controls (0.28 ± 0.114 U/mg protein), HFD + LA (0.231 ± 0.02 U/mg protein) and HFD + Q (0.182 ± 0.096 U/mg protein) at 26 weeks. Moreover, Na⁺/K⁺-ATPase and Ca^2 +-ATPase activities increased in HFD mice whereas NOS reduced. A 1.5-fold increase in TRα1 and reduction in expression of the deiodinase iodothyronine DIO1, threonine protein kinase and NOS3 as well as up-regulation of AT1α, ACE, ATP1B1, GSK3β and Cja1 genes also occurred in HFD mice. Conversely, LA, Q and R inhibited weight gain; reduced TRα1 expression as well as increased DIO1; reduced ACE activity and AT1α, ATP1B1 and Cja1 gene expression as well as inhibited GSK3β; increased total antioxidant capacity, GSH and catalase activity; and reduced blood pressure. In conclusion, LA, resveratrol and quercetin supplementation reduces obesity thereby restoring plasma thyroid hormone levels and attenuating oxidative stress in the heart and thus may have therapeutic potential in heart diseases.     

Inhibition of endogenous thioredoxin-1 in the heart of transgenic mice does not confer cardioprotection in ischemic postconditioning

Thioredoxin-1 maintains the cellular redox status and decreases the infarct size in ischemia/reperfusion injury. However, whether the increase of thioredoxin-1 expression or its lack of activity modifies the protection conferred by ischemic postconditioning has not been yet elucidated. The aim was to evaluate if the thioredoxin-1 overexpression enhances the posctconditioning protective effect, and whether the lack of the activity abolishes the reduction of the infarct size. Wild type mice hearts, transgenic mice hearts overexpressing thioredoxin-1, and a dominant negative mutant (C32S/C35S) of thioredoxin-1 were used. The hearts were subjected to 30 min of ischemia and 120 min of reperfusion (Langendorff) (I/R group) or to postconditioning protocol (PostC group). The infarct size in the Wt-PostC group decreased in comparison to the Wt-I/R group (54.6 ± 2.4 vs. 39.2 ± 2.1%, p < 0.05), but this protection was abolished in DN-Trx1-PostC group (49.7 ± 1.1%). The ischemia/reperfusion and postconditioning in mice overexpressing thioredoxin-1 reduced infarct size at the same magnitude (35.9 ± 2.1 and 38.4 ± 1.3%, p < 0.05 vs. Wt-I/R). In Wt-PostC, Trx1-I/R and Trx1- PostC, Akt and GSK3β phosphorylation increased compared to Wt-I/R, without changes in DN-Trx1 groups. In conclusion, given that the cardioprotection conferred by thioredoxin-1 overexpression and postconditioning, is accomplished through the activation of the Akt/GSK3β survival pathway, no synergic effect was evidenced. Thioredoxin-1 plays a key role in the postconditioning, given that when this protein is inactive the cardioprotective mechanism was abolished. Thus, diverse comorbidities or situations modifying the thioredoxin activity, could explain the absence of this strong mechanism of protection in different clinical situations.     

Inhibition of human vascular NADPH oxidase by apocynin derived oligophenols

Enzymatic oxidation of apocynin, which may mimic in vivo metabolism, affords a large number of oligomers (apocynin oxidation products, AOP) that inhibit vascular NADPH oxidase. In vitro studies of NADPH oxidase activity were performed to identify active inhibitors, resulting in a trimer hydroxylated quinone (IIIHyQ) that inhibited NADPH oxidase with an IC₅₀ = 31 nM. Apocynin itself possessed minimal inhibitory activity. NADPH oxidase is believed to be inhibited through prevention of the interaction between two NADPH oxidase subunits, p47^phox and p22^phox. To that end, while apocynin was unable to block the interaction of his-tagged p47^phox with a surface immobilized biotinylated p22^phox peptide, the IIIHyQ product strongly interfered with this interaction (apparent IC₅₀ = 1.6 μM). These results provide evidence that peroxidase-generated AOP, which consist of oligomeric phenols and quinones, inhibit critical interactions that are involved in the assembly and activation of human vascular NADPH oxidase.     

Effect of preischemic β-adrenoceptor stimulation on postischemic contractile dysfunction

AimsShort periods of preischemic β-adrenoceptor stimulation protect hearts against postischemic left ventricular dysfunction. It was the aim of this study to decide whether this procedure mimics ischemic preconditioning by the generation of preischemic hemodynamic and energetic stress or whether it represents an endogenous phenomenon and to investigate the influence of age and hypertension.Main methodsIsolated rat hearts were investigated ex vivo by Langendorff perfusion and exposed to an established ischemia/reperfusion protocol (45 min no-flow ischemia and 90 min reperfusion). Left ventricular developed pressure (LVDP), rate pressure product, and ± dP/dt were analyzed.Key findingsIsoprenaline concentration dependently increased LVDP up to 40 ± 15 mm Hg (approximately EC₅₀ of 9.9 ± 0.5 nM). Isoprenaline given prior to ischemia attenuated the subsequent postischemic ventricular dysfunction (approximately EC₅₀ of 1.4 ± 0.2 pM). However, concentrations high enough to improve LVDP in normoxic hearts did not improve postischemic recovery albeit a significant reduction of hypercontraction-induced cell damage. The effect on functional recovery was attenuated by atenolol, H89, and wortmannin suggesting that β-adrenoceptor stimulation, protein kinase A, and PI 3-kinase activation are involved. The effect was conserved in hearts from 13 month old rats but lost in age-matched spontaneously hypertensive rats.SignificanceThe study identifies preischemic β-adrenoceptor stimulation as a pharmacological preconditioning protocol that does not simply mimic classical ischemic preconditioning by induction of hemodynamic or energetic stress prior to a prolonged ischemic period. The observed loss of effectiveness in hypertensives may contribute to the reduced ischemic tolerance of hypertensives.     

Mrp-8 and -14 mediate CNS injury in focal cerebral ischemia

Several reports have recently demonstrated a detrimental role of Toll-like receptors (TLR) in cerebral ischemia, while there is little information about the endogenous ligands which activate TLR-signaling. The myeloid related proteins-8 and-14 (Mrp8/S100A8; Mrp14/S100A9) have recently been characterized as endogenous TLR4-agonists, and thus may mediate TLR-activation in cerebral ischemia. Interestingly, not only TLR-mRNAs, but also Mrp8 and Mrp14 mRNA were found to be induced in mouse brain between 3 and 48 h after transient 1 h focal cerebral ischemia/reperfusion. Mrp-protein was expressed in the ischemic hemisphere, and co-labeled with CD11b-positive cells. To test the hypothesis that Mrp-signaling contributes to the postischemic brain damage, we subjected Mrp14-deficient mice, which also lack Mrp8 protein expression, to focal cerebral ischemia. Mrp14-deficient mice had significantly smaller lesion volumes when compared to wild-type littermates (130 ± 16 mm³ vs. 105 ± 28 mm³) at 2 days after transient focal cerebral ischemia (1 h), less brain swelling, and a reduced macrophage/microglia cell count in the ischemic hemisphere. We conclude that upregulation and signaling of Mrp-8 and-14 contribute to neuroinflammation and the progression of ischemic damage.     

Neuroprotective effect of ischemic preconditioning via modulating the expression of adropin and oxidative markers against transient cerebral ischemia in diabetic rats

IntroductionIschemic preconditioning (IPreC) can render the brain more tolerant to a subsequent potential lethal ischemic injury. Hyperglycemia has been shown to increase the size of ischemic stroke and worsen the clinical outcome following a stroke, thus exacerbating oxidative stress. Adropin has a significant association with cardiovascular disease, especially with diabetes. In this study, we aimed to evaluate the role of the IPreC due to modulating the expression of adropin and oxidative damage markers against stroke by induced transient middle cerebral artery occlusion (MCAo) in streptozotocin (STZ)-induced diabetic rats.Material-method72 male Spraque Dawley rats were allocated to 8 groups. In order to evaluate alterations of anti/oxidative status and adropin level, we induced transient MCAo seven days after STZ-induced diabetes. Also we performed IPreC 72 h before transient MCAo to assess whether IPreC could have a neuroprotective effect against ischemia-reperfusion injury.ResultsThe general characteristics of STZ-treated rats (STZ) included reduced body weight and elevated blood glucose levels compared to non-diabetic ones. Ischemic preconditioning before cerebral ischemia significantly reduced infarction size compared with the other groups [IPreC + MCAo (27 ± 11 mm³) vs. MCAo (109 ± 17 mm³) p < 0.001; STZ + IPreC + MCAo (38 ± 10 mm³) vs. STZ + MCAo (165 ± 45 mm³) p < 0.001, respectively]. The mean total antioxidant status level in IPreC groups was higher than other groups (p ≤ 0.05). Moreover, IPreC considerably decreased mean adropin levels compared with other groups (p ≤ 0.05).ConclusionThe study results supported the neuroprotective effects of ischemic preconditioning in MCA infarcts correlated with the level of oxidative damage markers and adropin.     

Effect of total flavonoids of Radix Ilicis pubescentis on cerebral ischemia reperfusion model

This paper aims to observe the effects of total flavonoids of Radix Ilicis pubescentis on mouse model of cerebral ischemia reperfusion. Mice were orally given different doses of total flavonoids of Radix Ilicis pubescentis 10 d, and were administered once daily. On the tenth day after the administration of 1 h in mice after anesthesia, we used needle to hook the bilateral common carotid artery (CCA) for 10 min, with 10 min ischemia reperfusion, 10 min ischemia. Then we restored their blood supply, copy the model of cerebral ischemia reperfusion; We then had all mice reperfused for 24 h, and then took their orbital blood samples and measured blood rheology. We quickly removed the brain, with half of the brain having sagittal incision. Then we fixed the brains and sectioned them to observe the pathological changes of brain cells in the hippocampus and cortex. We also measured the other half sample which was made of brain homogenate of NO, NOS, Na⁺-K⁺-, ATP enzyme Mg²⁺-ATPase and Ca²⁺-ATPase. Acupuncture needle hook occlusion of bilateral common carotid arteries can successfully establish the model of cerebral ischemia reperfusion. After comparing with the model mice, we concluded that Ilex pubescens flavonoids not only reduce damage to the brain nerve cells in the hippocampus and cortex, but also significantly reduce the content of NO in brain homogenate, the activity of nitric oxide synthase (NOS) and increases ATP enzyme activity (P < 0.05, P < 0.01). In this way, cerebral ischemia reperfusion injury is improved. Different dosages of Ilex pubescens flavonoids on mouse cerebral ischemia reperfusion model have good effects.     

HIV proteins (gp120 and Tat) and methamphetamine in oxidative stress-induced damage in the brain: Potential role of the thiol antioxidant N-acetylcysteine amide

An increased risk of HIV-1 associated dementia (HAD) has been observed in patients abusing methamphetamine (METH). Since both HIV viral proteins (gp120, Tat) and METH induce oxidative stress, drug abusing patients are at a greater risk of oxidative stress-induced damage. The objective of this study was to determine if N-acetylcysteine amide (NACA) protects the blood brain barrier (BBB) from oxidative stress-induced damage in animals exposed to gp120, Tat and METH. To study this, CD-1 mice pre-treated with NACA/saline, received injections of gp120, Tat, gp120 + Tat or saline for 5 days, followed by three injections of METH/saline on the fifth day, and sacrificed 24 h after the final injection. Various oxidative stress parameters were measured, and animals treated with gp120 + Tat + Meth were found to be the most challenged group, as indicated by their GSH and MDA levels. Treatment with NACA significantly rescued the animals from oxidative stress. Further, NACA-treated animals had significantly higher expression of TJ proteins and BBB permeability as compared to the group treated with gp120 + Tat + METH alone, indicating that NACA can protect the BBB from oxidative stress-induced damage in gp120, Tat and METH exposed animals, and thus could be a viable therapeutic option for patients with HAD.     

High-selenium lentil diet protects against arsenic-induced atherosclerosis in a mouse model

Background: Cardiovascular disease (CVD) is a major cause of death worldwide, and arsenic (As) intake, mainly through drinking water, is a well-known risk factor for CVD as well as other health problems. Selenium (Se) is a known antagonist to As toxicity. Objective: We tested the potential of high-Se lentils from the Canadian prairies as a therapeutic food to alter the outcome of As-enhanced atherosclerosis. Materials and Methods: Male ApoE^−/− mice exposed to a moderate level of As (200 ppb) in their drinking water, and control mice on tap water received one of three lentil diets: Se-deficient (0.009 mg/kg), Se-adequate (0.16 mg/kg) or Se-high (0.3 mg/kg). After 13 weeks, lesion formation in the aortic arch and sinus were assessed. Intralesional cellular composition, serum lipid levels and hepatic oxidative stress were assessed as well. Results: Arsenic-exacerbated plaque formation was reduced in the sinus and completely abolished in the aortic arch of mice on the Se-fortified lentil diet, whereas lesions were increased in As-exposed mice on both the Se-deficient and Se-adequate diets. Notably, Se deficiency contributed to proatherogenic composition of serum lipids in As-exposed mice as indicated by high-density lipoprotein:low-density lipoprotein. At least adequate Se status was crucial for counteracting As-induced oxidative stress. Conclusion: This study is the first to show the potential of high-Se lentils to protect against As-triggered atherosclerosis, and this invites further investigations in human populations at risk from As contamination of their drinking water.     

Effect of NaCl on growth and Cd accumulation of halophyte Spartina alterniflora under CdCl2 stress

A study quantifying the effect of NaCl on growth and Cd accumulation of Spartina alterniflora subjected to Cd stress was conducted. Seedlings were cultivated in the presence of 1 or 3 mM Cd alone, or combined with NaCl (50 or 100 mM). The results showed that NaCl magnified the phytotoxicity of moderate Cd stress (1 mM Cd) on plants due to reduced levels of plant biomass, plant height, and chlorophyll a + b, while no synergistic effects were recorded under severe Cd stress (3 mM Cd). Proline and Ca^2 + accumulated along with additional NaCl under moderate Cd stress, instead of reduced or unchanged levels under severe Cd stress owing to different adoption strategies caused by NaCl under different Cd stresses. NaCl reduced the oxidative stress in Cd-treated plants through increasing levels of antioxidative enzymes (catalase (CAT) and peroxidase (POD)) under moderate Cd stress. With NaCl addition, Cd^2 + contents in S. alterniflora increased and reduced under moderate and severe Cd stress, respectively. However, total Cd^2 + amounts increased with increasing NaCl concentration due to biological dilution. NaCl improved the increase of Cd^2 + translocation factor (TF) under moderate Cd stress, indicating that NaCl might improve Cd^2 + uptake and translocation from roots to shoots, and enhance the phytoextraction of S. alterniflora on Cd; while phytostabilization of Cd under severe Cd stress may be possible due to the reduced TF. Thus, NaCl alleviated phytotoxicity caused by Cd stress through improved management of osmotic solutes and oxidative status, and affected Cd accumulations in S. alterniflora differently under moderate and severe Cd stresses.     

Novel hypoglycemic effects of Ganoderma lucidum water-extract in obese/diabetic (+db/+db) mice

In this study, we evaluated the pharmacological effects of Ganoderma lucidum (G. lucidum) (water-extract) (0.003, 0.03 and 0.3 g/kg, 4-week oral gavage) consumption using the lean (+db/+m) and the obese/diabetic (+db/+db) mice. Different physiological parameters (plasma glucose and insulin levels, lipoproteins-cholesterol levels, phosphoenolpyruvate carboxykinase (PEPCK), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA reductase) and isolated aorta relaxation of both species were measured and compared. G. lucidum (0.03 and 0.3 g/kg) lowered the serum glucose level in +db/+db mice after the first week of treatment whereas a reduction was observed in +db/+m mice only fed with 0.3 g/kg of G. lucidum at the fourth week. A higher hepatic PEPCK gene expression was found in +db/+db mice. G. lucidum (0.03 and 0.3 g/kg) markedly reduced the PEPCK expression in +db/+db mice whereas the expression of PEPCK was attenuated in +db/+m mice (0.3 g/kg G. lucidum). HMG CoA reductase protein expression (in both hepatic and extra-hepatic organs) and the serum insulin level were not altered by G. lucidum. These data demonstrate that G. lucidum consumption can provide beneficial effects in treating type 2 diabetes mellitus (T2DM) by lowering the serum glucose levels through the suppression of the hepatic PEPCK gene expression.     

Changes in proline accumulation and antioxidative enzyme activities in Groenlandia densa under cadmium stress

In this study an experiment was carried out to study the process of stress adaptation in Groenlandia densa (opposite-leaved pondweed) grown under cadmium stress (0–20 mg L^?1 Cd). The results showed that Cd concentrations in plants increased with increasing Cd supply levels and reached a maximum of 0.43 mg kg^?1 DW at 0.5 mg L^?1 Cd concentrations. The level of photosynthetic pigments and soluble proteins decreased only upon exposure to high Cd concentrations. At the same time, the level of malondialdehyde (MDA) increased with increasing Cd concentration. These results suggested an alleviation of stress that was presumably the result of by antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST) as well as ascorbate peroxidase (APX), which increased linearly with increasing Cd levels. Cellular antioxidants levels showed a decline suggesting a defensive mechanism to protect against oxidative stress caused by Cd. In addition, the proline content in G. densa increased with increasing cadmium levels. These findings suggest that G. densa is equipped with an efficient antioxidant mechanism against Cd-induced oxidative stress which protects the plant's photosynthetic machinery from damage.Our present work concluded that G. densa has a high level of Cd tolerance and accumulation. We also found that moderate Cd treatment (0.05–5 mg L^?1 Cd) alleviated oxidative stress in plants, while the addition of higher amounts of Cd (10–20 mg L^?1) could cause an increasing generation of ROS, which was effectively scavenged by the antioxidative system.     

Niacin bound chromium treatment induces myocardial Glut-4 translocation and caveolar interaction via Akt,AMPK and eNOS phosphorylation in streptozotocin induced diabetic rats after ischemia-reperfusion injury

Diabetes, one of the major risk factors of metabolic syndrome culminates in the development of Ischemic Heart Disease (IHD). Refined diets that lack micronutrients, mainly trivalent chromium (Cr³⁺) have been identified as the contributor in the rising incidence of diabetes. We investigated the effect of niacin-bound chromium (NBC) during ischemia/reperfusion (IR) injury in streptozotocin induced diabetic rats. Rats were randomized into: Control (Con); Diabetic (Dia) and Diabetic rats fed with NBC (Dia + NBC). After 30 days of treatment, the isolated hearts were subjected to 30 min of global ischemia followed by 2 h of reperfusion. NBC treatment demonstrated significant increase in left ventricular functions and significant reduction in infarct size and cardiomyocyte apoptosis in Dia + NBC compared with Dia. Increased Glut-4 translocation to the lipid raft fractions was also observed in Dia + NBC compared to Dia. Reduced Cav-1 and increased Cav-3 expression along with phosphorylation of Akt, eNOS and AMPK might have resulted in increased Glut-4 translocation in Dia + NBC. Our results indicate that the cardioprotective effect of NBC is mediated by increased activation of AMPK, Akt and eNOS resulting in increased translocation of Glut-4 to the caveolar raft fractions thereby alleviating the effects of IR injury in the diabetic myocardium.     

Protective effect of curcumin against intracerebral streptozotocin induced impairment in memory and cerebral blood flow

AimsThe aim of the present study is to investigate the effect of curcumin on cerebral blood flow (CBF), memory impairment, oxidative stress and cholinergic dysfunction in intracerebral (IC) streptozotocin (STZ) induced memory impairment in mice.Main methodsMemory impairment was induced by STZ (0.5 mg/kg, IC) administered twice with an interval of 48 h in mice. Memory function was assessed by Morris water maze and passive avoidance test. CBF was measured by Laser Doppler Flowmetry (LDF). To study the preventive effect, curcumin (10, 20 and 50 mg/kg, PO) was administered for 21 days starting from the first dose of STZ. In another set of experiment, curcumin was administered for 7 days from 19th day after confirming STZ induced dementia to observe its therapeutic effect. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain on day 21.Key findingsThe major finding of this study is that STZ (IC) caused a significant reduction in CBF along with memory impairment, cholinergic dysfunction and enhanced oxidative stress. Curcumin dose dependently improved CBF in STZ treated mice together with amelioration of memory impairment both in preventive and therapeutic manner.SignificanceThe present study clearly demonstrates the beneficial effects of curcumin, the dietary staple of India, on CBF, memory and oxidative stress which can be exploited for dementia associated with age related vascular and neurodegenerative disorders.     

Synthesis and pharmacological validation of a novel series of non-steroidal FXR agonists

To overcome the known liabilities of GW4064 a series of analogs were synthesized where the stilbene double bond is replaced by an oxymethylene or amino-methylene linker connecting a terminal benzoic acid with a substituted heteroaryl in the middle ring position. As a result we discovered compounds with increased potency in vitro that cause dose-dependent reduction of plasma triglycerides and cholesterol in db/db mice down to 2 × 1 mg/kg/day upon oral administration.     

Glyceollin improves endoplasmic reticulum stress-induced insulin resistance through CaMKK-AMPK pathway in L6 myotubes

Glyceollin has been shown to have antidiabetic properties, although its molecular mechanism is not known. Here, we have investigated the metabolic effects of glyceollin in animal models of insulin resistance and in endoplasmic reticulum (ER) stress-responsive muscle cells. db/db mice were treated with glyceollin for 4 weeks and triglycerides, total cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) levels were measured. Glyceollin reduced serum insulin and triglycerides and increased HDL levels in db/db mice. Furthermore, glyceollin caused a significant improvement in glucose homeostasis without altering body weight and food intake in db/db mice. In muscle cells, glyceollin increased the activity of AMP-activated protein kinase (AMPK) as well as cellular glucose uptake. Fatty acid oxidation was also increased. In parallel, phosphorylation of acetyl-CoA carboxylase (ACC) at Ser-79 was increased, consistent with decreased ACC activity. An insulin-resistant state was induced by exposing cells to 5 μg/ml of tunicamycin as indicated by decreased insulin-mediated tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and glucose uptake. Inhibition of insulin-mediated tyrosine phosphorylation of IRS-1 and glucose uptake under ER stress was prevented by glyceollin. Strikingly, glyceollin reduced ER stress-induced, c-Jun NH₂-terminal kinase activation and subsequently increased insulin signaling via stimulation of AMPK activity in L6 myotubes. Pharmacologic inhibition or knockdown of Ca²⁺/calmodulin-dependent protein kinase kinase blocked glyceollin-increased AMPK phosphorylation and insulin sensitivity under ER stress conditions. Taken together, these results indicate that glyceollin-mediated enhancement of insulin sensitivity under ER stress conditions is predominantly accomplished by activating AMPK, thereby having beneficial effects on hyperglycemia and insulin resistance.     

Enhanced ROS production by NADPH oxidase is correlated to changes in antioxidant enzyme activity in human heart failure

In pathological conditions, the balance between reactive oxygen species (ROS) and antioxidants may shift toward a relative increase of ROS, resulting in oxidative stress. Conflicting data are available on antioxidant defenses in human failing heart and they are limited to the left ventricle. Thus, we aimed to investigate and compare the source of oxidant and antioxidant enzyme activities in the right (RV) and left (LV) ventricles of human failing hearts. We found a significant increase in superoxide production only by NADPH oxidase in both failing ventricles, more marked in RV. Despite unchanged mRNA or protein expression, catalase (CAT) and glutathione peroxidase (GPx) activities were increased, and their increases reflected the levels of Tyr phosphorylation of the respective enzyme. Manganese superoxide dismutase (Mn-SOD) activity appeared unchanged. The increase in NADPH oxidase-dependent superoxide production positively correlated with the activation of both CAT and GPx. However, the slope of the linear correlation (m) was steeper in LV than in RV for GPx (LV: m = 2.416; RV: m = 1.485) and CAT (LV: m = 1.007; RV: m = 0.354). Accordingly, malondialdehyde levels, an indirect index of oxidative stress, were significantly higher in the RV than LV. We conclude that in human failing RV and LV, oxidative stress is associated with activation of antioxidant enzyme activity. This activation is likely due to post-translational modifications and more evident in LV. Overall, these findings suggest a reduced protection of RV against oxidative stress and its potential contribution to the progression toward overt heart failure.