Effects of lncRNA MALAT1-mediated ß-catenin signaling pathway on myocardial cell apoptosis in rats with myocardial ischemia/reperfusion injury.

OBJECTIVE: To investigate the effects of long non-coding ribonucleic acid (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on myocardial ischemia/reperfusion (I/R) injury in rats and its mechanism, and to provide a certain reference for the clinical prevention and treatment of myocardial infarction. MATERIALS AND METHODS: A total of 60 male Sprague-Dawley rats were divided into 3 groups using a random number table, including the Sham group (n=20), I/R group (n=20) and I/R + MALAT1 small interfering RNA (siRNA) group (n=20). An I/R model was established by means of recanalization after ligation of the left anterior descending coronary artery of the rats. The rats in the I/R + MALAT1 siRNA group were used to establish a model of MALAT1 knockdown by injecting MALAT1 siRNA from the tail vein. The myocardial infarction area in each group was detected via 2,3,5-triphenyl tetrazolium chloride (TTC) staining. The ejection fraction% (EF%) and fractional shortening% (FS%) of the heart in each group were measured through echocardiography. Hematoxylin and eosin (H&E) staining was adopted to determine the morphological changes in myocardial cells in each group. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was performed to detect the apoptosis levels of myocardial cells and fibroblasts in the cardiac tissues in each group, and Western blotting assay was conducted to measure the expression levels of apoptosis-related proteins [B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax)]. In addition, the content of ß-catenin in the three groups of rats was determined via immunohistochemical staining. Finally, the impacts of MALAT1 siRNA on the expression level of ß-catenin protein were detected using Western blotting assay. RESULTS: MALAT1 siRNA could prominently ameliorate the I/R-induced cardiac insufficiency in the rats and improve the EF% and FS% of the heart (p<0.05). Moreover, MALAT1 siRNA was able to remarkably inhibit the I/R injury-induced myocardial infarction, reducing the infarction area from (59.54±3.45) to (24.85±1.30; p<0.05). The results of the H&E staining indicated that compared with those in the I/R group, the myofilaments of the myocardial cells were well-arranged, the degrees of degradation and necrosis of the myofilaments declined, and the cellular edema was relieved markedly in the I/R + MALAT1 siRNA group. It was shown in the results of immunohistochemistry and Western blotting that MALAT1 siRNA could notably reverse the I/R-induced up-regulation of ß-catenin expression (p<0.05). CONCLUSIONS: MALAT1 knockdown can significantly ameliorate the I/R-induced myocardial injury and improve the cardiac function of the rats, whose mechanism is probably correlated with the inhibition of MALAT1 siRNA on ß-catenin. Therefore, MALAT1 siRNA is expected to become a new target for the treatment of myocardial infarction.

Aldose reductase inhibitor Epalrestat alleviates high glucose-induced cardiomyocyte apoptosis via ROS.

OBJECTIVE: To clarify the role of aldose reductase inhibitor (ARI) in the high glucose-induced cardiomyocyte apoptosis and its mechanism. MATERIALS AND METHODS: In this study, H9c2 cardiomyocytes were employed as objects, high-glucose medium as stimulus, and ARI Epalrestat as a therapeutic drug. The cell apoptosis and activity changes of nitric oxide synthase (NOS), NO, and reactive oxygen species (ROS) were evaluated via Hoechst staining, enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), and Western blotting. In addition, the mitochondrial membrane potential was measured via fluorescence counting. RESULTS: Epalrestat inhibited the activity of AR to improve high glucose-induced oxidative stress in cardiomyocytes, weaken ROS activity, relieve the inhibition on NO activity, alleviate mitochondrial membrane potential damage, reduce the level of high glucose-induced cardiomyocyte apoptosis, and suppress the expression and activity of Caspase-3, thereby preventing high glucose-induced cardiomyocyte apoptosis. CONCLUSIONS: ARI protects against high glucose-induced cardiomyocyte apoptosis.

The effects of a fat- and sugar-enriched diet and chronic stress on nonalcoholic fatty liver disease in male Wistar rats.

PURPOSE: The pathogenesis of nonalcoholic fatty liver disease (NAFLD) is still under debate. The aim of this study was to investigate the effects of a long-term fat- and sugar-enriched diet (FSED) and chronic stress (CS) on NAFLD. METHODS: Male Wistar rats were fed on either a standard diet or a FSED and given CS, a random electric foot shock (2 hr/morning and afternoon per day), or not for 12 weeks. After the experimental period, epididymal adipose tissue weight, sign of visceral obesity (VO), and hepatic index (HI) were measured. At sacrifice blood samples and liver were obtained. Histology of the liver was blindly determined by a pathologist. RESULTS: Histopathologically, moderate to severe steatosis, ballooning hepatocytes, and portal or lobules inflammation were observed in the FSED+CS group. However, mild to moderate steatosis with a few portal inflammation in the FSED group and mild steatosis or not with a few portal inflammation in the CS group were found correspondingly. In addition, more severe blood-fat disorder, high HI, fatty metabolic dysfunction, oxidative stress, high expressions of C-reactive protein mRNA and low expressions of peroxisome proliferator-activated receptor alpha mRNA in the liver were also revealed in the FSED+CS group. But, the degree of VO was not different between the FSED and FSED+CS groups. CONCLUSION: The observations strongly suggest that chronic stress can aggravate fat- and sugar-enriched diet-induced NAFLD from steatosis to steatohepatitis in male Wistar rats, although VO is not changed.