Circadian Influences on Myocardial Ischemia-Reperfusion Injury and Heart Failure.

The impact of circadian rhythms on cardiovascular function and disease development is well established, with numerous studies in genetically modified animals emphasizing the circadian molecular clock's significance in the pathogenesis and pathophysiology of myocardial ischemia and heart failure progression. However, translational preclinical studies targeting the heart's circadian biology are just now emerging and are leading to the development of a novel field of medicine termed circadian medicine. In this review, we explore circadian molecular mechanisms and novel therapies, including (1) intense light, (2) small molecules modulating the circadian mechanism, and (3) chronotherapies such as cardiovascular drugs and meal timings. These promise significant clinical translation in circadian medicine for cardiovascular disease. (4) Additionally, we address the differential functioning of the circadian mechanism in males versus females, emphasizing the consideration of biological sex, gender, and aging in circadian therapies for cardiovascular disease.

Circadian influence on the microbiome improves heart failure outcomes.

Myocardial infarction (MI) leading to heart failure (HF) is a major cause of death worldwide. Previous studies revealed that the circadian system markedly impacts cardiac repair post-MI, and that light is an important environmental factor modulating the circadian influence over healing. Recent studies suggest that gut physiology also affects the circadian system, but how it contributes to cardiac repair post-MI and in HF is not well understood. To address this question, we first used a murine coronary artery ligation MI model to reveal that an intact gut microbiome is important for cardiac repair. Specifically, gut microbiome disruption impairs normal inflammatory responses in infarcted myocardium, elevates adverse cardiac gene biomarkers, and leads to worse HF outcomes. Conversely, reconstituting the microbiome post-MI in mice with prior gut microbiome disruption improves healing, consistent with the notion that normal gut physiology contributes to cardiac repair. To investigate a role for the circadian system, we initially utilized circadian mutant Clock∆19/∆19 mice, revealing that a functional circadian mechanism is necessary for gut microbiome benefits on post-MI cardiac repair and HF. Finally, we demonstrate that circadian-mediated gut responses that benefit cardiac repair can be conferred by time-restricted feeding, as wake time feeding of MI mice improves HF outcomes, but these benefits are not observed in MI mice fed during their sleep time. In summary, gut physiology is important for cardiac repair, and the circadian system influences the beneficial gut responses to improve post-MI and HF outcomes.

Diallyl disulfide ameliorates isoproterenol induced cardiac hypertrophy activating mitochondrial biogenesis via eNOS-Nrf2-Tfam pathway in rats.

The beneficial effect of garlic on cardiovascular disease is well known. However, the use of raw garlic against cardiac hypertrophy is not established. In the present study we explored whether raw garlic and its compound, diallyl disulfide (DADS) could inhibit hypertrophy through H2S and/or mitochondrial biogenesis. Cardiac hypertrophy was induced in rat by giving isoproterenol at the dose of 5 mg/kg/day subcutaneously for 14 days through alzet minipump. Aqueous garlic homogenate, DADS and NaHS (liberate H2S) were fed to third, forth and fifth group of rats for 14 days at a dose of 250 mg/kg/day, 50 mg/kg/day, 14 µM/kg/day respectively. Garlic and DADS reduced cardiac hypertrophy markers and normalized mitochondrial ETC-complex activities, mitochondrial enzyme activites and mitochondrial biogenetic and apoptotic genes expression. Garlic and DADS enhanced eNOS and p-AKT level in rat heart along with increased NRF2 protein level and Tfam gene expression. However, normalization was not observed after administration of NaHS which generates H2S in-vivo. In conclusion, garlic and DADS induces mitochondrial biogenesis and ameliorates cardiac hypertrophy via activation of eNOS-Nrf2-Tfam pathway in rats.

Garlic and cardioprotection: insights into the molecular mechanisms.

Garlic is widely recognized for its immense therapeutic potential. Garlic has been shown to exert its beneficial effects against a wide spectrum of diseases, including cancer, diabetes, and microbial infections, as well as immunological and cardiovascular disorders. Most of the research on garlic has indicated that garlic and its active compounds are effective in reducing cardiovascular and metabolic risk by normalizing abnormal plasma lipids, oxidized low density lipoproteins, abnormal platelet aggregation, high blood pressure, and cardiac injury. Some of the beneficial effects of dietary garlic against cardiovascular disorders are mediated via the generation of hydrogen sulfide and nitric oxide in cardiomyocytes and endothelial cells. Garlic has the potential to protect the heart against myocardial infarction, doxorubicin-induced cardiotoxicity, arrhythmia, hypertrophy, and ischemia-reperfusion injury. The induction of cardiac endogenous antioxidants and the reduction of lipid peroxidation by garlic has been reported by several different groups. Other mechanisms, such as regulating ion channels, modulating Akt signaling pathways, histone deacetylase inhibition, and cytochrome P450 inhibition, could be responsible for the cardioprotective effect of garlic. Although several mechanisms have been identified for the cardioprotective effect of garlic, there is a need for further research to identify the specific molecular mechanism of cardioprotection in different cardiac diseases.

A proteomic view of isoproterenol induced cardiac hypertrophy: prohibitin identified as a potential biomarker in rats.

BACKGROUND: The present study aimed at using a proteomics based approach to: a) analyze and contrast the proteome of the healthy and isoproterenol induced hypertrophied hearts and b) identify potential biomarkers for diagnosis of cardiac hypertrophy. METHODS: Male Sprague Dawley (SD) rats were administered isoproterenol (ISO, 5 mg/kg, sc, once daily) for 14 days to induce cardiac hypertrophy. There was a significant (p<0.05) increase (~ 55%) in the heart weight to tail length ratio after 14 days of treatment and cardiac hypertrophy was evidenced by significant increase of ß-MHC and ANP, two indicative markers of cardiac hypertrophy, in the treated heart compared to that of control. Following confirmation of hypertrophy, 2DE of the tissue samples was done followed by MS/MS analysis of the protein spots to obtain a proteomic view for identification of novel biomarkers. RESULTS: Several important proteins were identified by proteomics analysis. They belong to the major functional categories such as cholesterol and protein metabolism, muscle contraction and development, transport, TCAcycle, ATP-biosynthesis, chaperone, signal transduction, DNA synthesis and ubiquitinisation. Careful examination of these protein spots by image analysis led to the successful identification of 7 differentially expressed proteins in the diseased sample. Further extension of this work for validation of differential expression of these proteins was also achieved by RTPCR and western blotting. CONCLUSIONS: Our results demonstrate characteristic protein expression profile in control and hypertrophy condition in SD rats and also expand the existing knowledge on differentially expressed proteins in hypertrophy. The study signifies the importance of reduced expression of a novel protein such as Prohibitin (PHB) which may be associated with the cardiomyocytes growth and cardiac hypertrophy. However, further work is necessary to confirm the role of PHB in human heart and its potential role in diagnostic and therapeutic intervention in the clinic.

Cardioprotective effect of ritonavir, an antiviral drug, in isoproterenol induced myocardial necrosis: a new therapeutic implication.

BACKGROUND: Ritonavir is a HIV protease inhibitor. In addition to its antiviral effect, Ritonavir directly inhibits the insulin-regulated glucose transporter GLUT4 and blocks glucose entry into fat and muscle cells. However, the effect of Ritonavir on cardiac GLUT4 inhibition during myocardial necrosis is not investigated. In the present study, we evaluated the role of Ritonavir in isoproterenol-induced myocardial necrosis in vivo and compared the effect with Phlorizin, a nonslective SGLTs inhibitor. METHODS: Isoproterenol (ISO) (150 mg/kg/day, i.p for 2 consecutive days) was administered to mice to cause myocardial necrosis. Phlorizin (400 mg/kg/day i.p twice daily for 2 days) and Ritonavir (10 mg/kg/day i.p twice daily for 2 days) were administered in two different groups of mice before isoproterenol administration. RESULTS AND DISCUSSION: Isoproterenol (ISO) (150 mg/kg/day, i.p for 2 consecutive days) administration caused significant (p < 0.05) increase in heart/body weight ratio, and myocardial necrosis as evident by significant (p < 0.05) increase in serum markers i.e. SGOT and CK; and cardiac histopathological changes. Significant (p < 0.05) reduction in myocardial SOD and catalase activities, and GSH level along with a significant (p < 0.05) rise in myocardial TBARS and nitric oxide levels were observed after ISO administration. However, administration of phlorizin, a SGLT1 inhibitor has been found to exhibit partial protection in ISO induced myocardial necrosis, as observed by significant decrease in heart/body weight ratio and myocardial nitric oxide level; significant increase in myocardial SOD and catalase activities along with no histopathological alterations. On the other hand, administration of ritonavir, a nonspecific GLUT inhibitor has been found to exhibit complete protection as observed by normalisation of heart/body weight ratio, serum markers, antioxidant enzymes activities and histopathological alterations. In vitro study with heart homogenate confirmed no antioxidant effect of ritonavir and phlorizin in the absence and presence of isoproterenol. CONCLUSIONS: Our study concluded that ritonavir, a nonspecific GLUT inhibitors showed complete protection in catecholamine induced myocardial necrosis.

Garlic provides protection to mice heart against isoproterenol-induced oxidative damage: role of nitric oxide.

Garlic has been widely recognized as a cardioprotective agent. However, the molecular mechanism of its cardioprotective effects is not well established. Here we hypothesized that aqueous garlic homogenate may mediate cardioprotection via nitric oxide (NO). Mice were fed with saline and aqueous garlic homogenate (250 and 500 mgkg(-1)day(-1) orally) for 30 days. In another set of experiment, mice were pre-treated with saline, aqueous garlic homogenate (AGH) (250 mgkg(-1)day(-1) for 30 days), and AGH (30 days) along with L-NAME (20 mgkg(-1)day(-1) i.p. for last 7 days) before inducing acute myocardial infarction by isoproterenol (s.c. injection of isoproterenol 150 mgkg(-1)day(-1) for 2 days) and sacrificed after 48 h. Dose dependent increase in serum NO level was observed after garlic 250 and 500 mgkg(-1) dose feeding. While no change in serum SGPT and SGOT level, a significant decrease in serum LDH level was observed after garlic feeding. Garlic-induced NO formation was further confirmed in human aortic endothelial cells (HAEC). Administration of isoproterenol caused a significant decrease in endogenous antioxidants i.e., myocardial catalase, GSH and GPx activity, and mitochondrial enzyme activities like citrate synthase and ß hydroxyacyl CoA dehydrogenase. All those deleterious cardiac changes induced by isoproterenol were significantly attenuated by garlic homogenate. However this beneficial effect of garlic was blunted when garlic was administered with L-NAME, a nonspecific inhibitor of nitric oxide synthase (NOS). Further, a significant increase in myocardial TBARS and decrease in total antioxidant activity was observed in L-NAME treated group compared to isoproterenol treated group. Administration of L-NAME in mice from control group lowered serum and cardiac NO levels without any change of oxidative stress parameters. In conclusion, our study provides novel evidence that garlic homogenate is protective in myocardial infarction via NO-signaling pathway in mice.

Immunomodulatory potential of rhizome and seed extracts of Nelumbo nucifera Gaertn.

ETHNOPHARMACOLOGICAL RELEVANCE: Nelumbo nucifera Gaertn. (Nymphaeaceae) is a well-known aquatic plant which has been used for the treatment of several disorders including skin disease, cough, inflammation, fever and many other disorders. AIM OF THE STUDY: To explore the immunomodulatory activity of extract of rhizome (NNRE) and seed (NNSE) of the plant. MATERIALS AND METHODS: The immunomodulatory activity of NNRE and NNSE was evaluated using various in vivo models including the total and differential leukocyte count (TLC and DLC), nitroblue-tetrazolium reduction (NBT) test, neutrophil adhesion test, phagocytic response and delayed type hypersensitivity (DTH) reaction. Sheep red blood cells (SRBC, 5 x 10(9)cells/ml) were used to immunize the animals. NNRE and NNSE at the doses of 100 and 300 mg/kg were administrated. RESULT: The TLC and lymphocyte count increased significantly but the neutrophil count was decreased for NNRE and NNSE treated groups compared to the control. A dose-dependent potentiation of DTH reaction induced by SRBC was observed from the extracts. The percentage of neutrophil adhesion to the nylon fiber was increased in NNRE treated groups (63.22 and 62.91%) compared to the NNSE treated group (54.86 and 54.23%). A potential phagocytic response was seen on treatment of the extracts, and significant changes were observed in the formation of formazone crystals. CONCLUSION: This finding suggests that the extract of rhizome and seed Nelumbo nucifera stimulate defense system by modulating several immunological parameters.