PPARγ activation improves the molecular and functional components of I(to) remodeling by angiotensin II

Diabetic cardiomyopathy was attenuated by cinnamon treatment through the inhibition of fibro-inflammatory response and ventricular hypertrophy in diabetic rats

Diabetic cardiomyopathy (DCM) is a chronic complication of diabetes that emphasizes the urgency of developing new drug therapies. With an illustrious history in traditional medicine to improve diabetes, cinnamon has been shown to possess blood lipids lowering effects and antioxidative and anti-inflammatory properties. However, the extent to which it protects the diabetic heart has yet to be determined. Forty-eight rats were administered in the study and grouped as: control; diabetic; diabetic rats given 100, 200, or 400 mg/kg cinnamon extract, metformin (300 mg/kg), valsartan (30 mg/kg), or met/val (combination of both drugs), via gavage for six weeks. Fasting blood sugar (FBS) and markers of cardiac injury including creatine kinase-muscle/brain (CK-MB), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were evaluated in blood samples. Malondialdehyde (MDA) levels, the total contents of thiol, superoxide dismutase (SOD), and catalase (CAT) activities were measured. Histopathology study and gene expression measurement of angiotensin II type 1 receptor (AT1), atrial natriuretic peptide (ANP), beta-myosin heavy chain (β-MHC), and brain natriuretic peptide (BNP) were done on cardiac tissue. FBS and cardiac enzyme indicators were reduced in all treated groups. A reduction in MDA level and enhancement in thiol content alongside with increase of SOD and CAT activities were observed in extract groups. The decrease of inflammation and fibrosis was obvious in treated groups, notably in the high-dose extract group. Furthermore, all treated diabetic groups showed a lowering trend in AT1, ANP, β-MHC, and BNP gene expression. Cinnamon extract, in addition to its hypoglycemic and antioxidant properties, can prevent diabetic heart damage by alleviating cardiac inflammation and fibrosis. PRACTICAL APPLICATIONS: This study found that cinnamon extract might protect diabetic heart damage by reducing inflammation and fibrosis in cardiac tissue, in addition to lowering blood glucose levels and increasing antioxidant activity. Our data imply that including cinnamon in diabetic participants' diets may help to reduce risk factors of cardiovascular diseases.

Molecular mechanisms in microRNA-mediated TRB3 gene and hypertension left ventricular hypertrophy

The present study investigated the relationship between microRNA-mediated TRB3 gene and hypertension left ventricular hypertrophy at the molecular level. Polymorphic site in TRB3 gene was identified by direct PCR method, and the correlation between the SNP site and ventricular hypertrophy was determined. MicroRNAs target gene sequence interacting on the TRB3 polymorphic site was screened by bioinformatics, and the effect of microRNAs on the TRB3 polymorphic site was finally verified by luciferase test. Two polymorphic sites rs6186912 and rs6186923 were found in the TRB3 gene, and the direct relationship between rs6186923 polymorphic site and the hypertension left ventricular hypertrophy in patients with myocardial hypertrophy was compared and analyzed. Pictar software was used to analyze the effect of miR-100 on rs6186923, and the argumentation was verified by luciferase test. In conclusion, the study showed that the TRB3 gene polymorphism rs6186923 was able to affect the TRB3 gene by affecting the binding of miR-100, which indirectly caused the formation of hypertension left ventricular hypertrophy.

Changes in levels of angiotensin II and its receptors in a model of inverted stress-induced cardiomyopathy

Background

Stress-induced cardiomyopathy (SIC) has gained increasing attention worldwide and is characterized by extensive ventricular akinesis, Beta-blockers and angiotensin-converting enzyme inhibitors (ACEIs) are the main treatments for SIC patients. The pharmacological mechanism of action of beta-blockers results in the inhibition of the biological effects of catecholamines. However, the mechanism of action of ACEIs in the treatment of cardiomyopathy is not known. Our aim is to assess changes in levels of angiotensin II, angiotensin-II receptors and ACE responses to SIC.

Methods

A model of inverted SIC was established in rabbits by vagal electrical stimulation. The serum concentration of angiotensin II and angiotensin (1-7) was detected by enzyme-linked immunosorbent assay. Expression of angiotensin-II receptors was measured by Western blotting and real-time reverse transcription-polymerase chain reaction (RT-PCR), with localization detected by immunofluorescent staining. ACE-II expression in the myocardium was measured by Western blotting.

Results

From one day after vagal stimulation, concentrations of angiotensin II were significantly higher in the experimental group than those in the control group (P <0.05). Stress induced a time-dependent decrease in angiotensin subtype-1 (AT1) expression and a time-dependent increase in AT2 expression only in the apical portion of the myocardium. From three days after vagal stimulation, angiotensin (1-7) levels were significantly lower in the experimental group compared with the control group (P <0.05). Expression of the ACE-II protein was significantly downregulated in the experimental group compared with the control group from three days after vagal stimulation (P <0.05).

Conclusions

Expression of angiotensin II, its receptors, ACE-II and angiotensin (1-7) was altered in response to SIC. The renin-angiotensin system could represent a therapeutic target in the prevention of SIC.

Electronic supplementary material

The online version of this article (doi:10.1186/s40001-014-0054-8) contains supplementary material, which is available to authorized users.

Pioglitazone improves potassium channel remodeling induced by angiotensin II in atrial myocytes

BACKGROUND

It has been demonstrated that atrial electrical remodeling contributes toward atrial fibrillation (AF) maintenance, and that angiotensin II (AngII) is involved in the pathogenesis of atrial electrical remodeling. Peroxisome proliferator activated receptor-γ (PPAR-γ) agonists have been shown to inhibit atrial electrical remodeling, but the underlying mechanisms are poorly understood. In the present study we investigated the regulating effects of PPAR-g agonist on AngII-induced potassium channel remodeling in atrial myocytes.

MATERIAL/METHODS

Whole-cell patch-clamp technique was used to record transient outward potassium current (Ito), ultra-rapid delayed rectifier potassium (Ikur), and inward rectifier potassium current (Ik1). Real-time PCR was used to assess potassium channel subunit mRNA expression.

RESULTS

Compared with the control group, AngII reduced Ito and Ikur current density as well as amplified Ik1 current density, which were partially prevented by pioglitazone. Furthermore, pioglitazone alleviated the downregulation of Ito subunit (Kv 4.2) and Ikur subunit (Kv 1.5), as well as the upregulation of Ik1 subunit (Kir 2.1 and Kir 2.2) mRNA expression stimulated by AngII.

CONCLUSIONS

These results suggest that pioglitazone exhibits a beneficial effect on AngII-induced potassium channel remodeling. PPAR-γ agonists may be potentially effective up-stream therapies for AF.

Pharmacokinetics, antitumor and cardioprotective effects of liposome-encapsulated phenylaminoethyl selenide in human prostate cancer rodent models

PURPOSE

Cardiotoxicity associated with the use of doxorubicin (DOX), and other chemotherapeutics, limits their clinical potential. This study determined the pharmacokinetics and antitumor and cardioprotective activity of free and liposome encapsulated phenyl-2-aminoethyl-selenide (PAESe).

METHODS

The pharmacokinetics of free PAESe and PAESe encapsulated in liposomes (SSL-PAESe) were determined in rats using liquid chromatography tandem mass-spectrometry. The antitumor and cardioprotective effects were determined in a mouse xenograft model of human prostate (PC-3) cancer and cardiomyocytes (H9C2).

RESULTS

The encapsulation of PAESe in liposomes increased the circulation half-life and area under the drug concentration time profile, and decreased total systemic clearance significantly compared to free PAESe. Free- and SSL-PAESe improved survival, decreased weight-loss and prevented cardiac hypertrophy significantly in tumor bearing and healthy mice following treatment with DOX at 5 and 12.5 mg/kg. In vitro studies revealed PAESe treatment altered formation of reactive oxygen species (ROS), cardiac hypertrophy and gene expression, i.e., atrial natriuretic peptide and myosin heavy chain complex beta, in H9C2 cells.

CONCLUSIONS

Treatment with free and SSL-PAESe exhibited antitumor activity in a prostate xenograft model and mitigated DOX-mediated cardiotoxicity.