Previous studies have shown an attenuating effect of ginsenoside Re on myocardial injury induced by hypoxia/reoxygenation (H/R). However, the underlying mechanism remains unclear. This study was designed to determine the underlying mechanism by which ginsenoside Re protects from myocardial injury induced by H/R. HL-1 cells derived from AT-1 mouse atrial cardiomyocyte tumor line were divided into control, H/R, and H/R + ginsenoside Re groups. Cell viability was measured by CCK-8 assay. ATP levels were quantified by enzymatic assays. Signaling pathway was predicted by network pharmacology analyses and verified by luciferase assay and gene-silencing experiment. The relationship between ginsenoside Re and its target genes and proteins was analyzed by docking experiments, allosteric site analysis, real-time PCR, and ubiquitination and immunoprecipitation assays. Our results showed that ginsenoside Re treatment consistently increased HL-1 cell viability and significantly up-regulated ATP levels after H/R-induced injury. Network pharmacology analysis suggested that the effect of ginsenoside Re was associated with the regulation of the Hypoxia-inducing factor 1 (HIF-1) signaling pathway. Silencing of HIF-1α abrogated the effect of ginsenoside Re on HL-1 cell viability, which was restored by transfection with an HIF-1α-expressing plasmid. Results of the bioinformatics analysis suggested that ginsenoside Re docked at the binding interface between HIF-1α and the von Hippel-Lindau (VHL) E3 ubiquitin ligase, preventing VHL from binding HIF-1α, thereby inhibiting the ubiquitination of HIF-1α. To validate the results of the bioinformatics analysis, real-time PCR, ubiquitination and immunoprecipitation assays were performed. Compared with the mRNA expression levels of the H/R group, ginsenoside Re did not change expression of HIF-1α mRNA, while protein level of HIF-1α increased and that of HIF-1α[Ub]n decreased following ginsenoside Re treatment. Immunoprecipitation results showed that the amount of HIF-1α bound to VHL substantially decreased following ginsenoside Re treatment. In addition, ginsenoside Re treatment increased the expression of GLUT1 (glucose transporter 1) and REDD1 (regulated in development and DNA damage response 1), which are targets of HIF-1α and are critical for cell metabolism and viability. These results suggested that Ginsenoside Re treatment attenuated the myocardial injury induced by H/R, and the possible mechanism was associated with the inhibition of HIF-1α ubiquitination.

Background Febuxostat, a novel nonpurine selective inhibitor of xanthine oxidase（XO）, may be used in the prevention and management of atrial fibrillation（AF）. The purpose of this study was to evaluate the effects of febuxostat on atrial remodeling in a rabbit model of AF induced by rapid atrial pacing（RAP） and the mechanisms by which it acts. Methods Twenty-four rabbits were randomly divided into four groups: sham-operated group（Group S）, RAP group（Group P）, RAP with 5 mg/kg per day febuxostat group（Group LFP）, and RAP with 10 mg/kg per day febuxostat group（Group HFP）. All rabbits except those in Group S were subjected to RAP at 600 beats/min for four weeks. The effects of febuxostat on atrial electrical and structural remodeling, markers of inflammation and oxidative stress, and signaling pathways involved in the left atrium were examined. Results Shortened atrial effective refractory period（AERP）, increased AF inducibility, decreased m RNA levels of Cav1.2 and Kv4.3, and left atrial enlargement and dysfunction were observed in Group P, and these changes were suppressed in the groups treated with febuxostat. Prominent atrial fibrosis was observed in Group P, as were increased levels of TGF-β1, Collagen I, and α-SMA and decreased levels of Smad7 and eNOS. Treatment with febuxostat attenuated these differences. Changes in inflammatory and oxidative stress markers induced by RAP were consistent with the protective effects of febuxostat. Conclusions This study is the first to find that febuxostat can inhibit atrial electrical and structural remodeling of AF by suppressing XO and inhibiting the TGF-β1/Smad signaling pathway.

Repeated exhaustive exercise could cause obvious oxidative stress-related injury in cardiomyocytes. This study was designed to investigate effects of allicin on rat myocardial oxidative injury during repeated exhaustive exercise, and its molecular mechanisms. Forty Sprague Dawley rats (6-7 wk old) were randomly divided into five groups: control (Control group); rats undergoing seven consecutive daily sessions of exhaustive swimming (SW group); and three groups of SW rats also receiving allicin at 4.2, 6.3 or 12.6 mg/kg for 7 d (SW+Allicin group). The effects of repeated exhaustive exercise on structural, functional and molecular biological changes in heart have been examined. Haematoxylin-eosin staining showed that treatment with allicin relieved myocardial cell swelling and inflammatory cell infiltration induced by repeated exhaustive exercise. Myocardial superoxide dismutase (SOD) activity was significantly reduced in the SW group compared with the Control group (P<0.01), while the levels of cardiac troponin T (cTnT), heart fatty acid binding protein (H-FABP), cortisol (COR), high sensitivity C reactive protein (hs-CRP), malondialdehyde (MDA), and the apoptotic index were significantly higher in the SW group than in the Control group (P<0.01). In addition, the protein levels of phosphorylated (p-) Akt, p-FOXO3a, Bcl-xL and nuclear sirtuin 1 (SIRT1) were significantly lower in the SW than in the Control group (P<0.01). All these effects were reversed by allicin (P<0.01). Allicin treatment significantly increased the activity of SOD, and inhibited the activities of cTnT, H-FABP, COR, hs-CRP and MDA, especially in the SW+Allicin (6.3 or 12.6 mg/kg) groups. Moreover, allicin treatment (4.2, 6.3 or 12.6 mg/kg) significantly increased the protein levels of p-Akt, p-FOXO3a, SIRT1, Bcl-xL compared with those in the SW group, while the protein levels of FOXO3a, Bax, cytochrome c and cleaved caspase-3 were changed in the opposite direction. These data suggested that allicin protected rat cardiomyocytes from oxidative stress-induced injury and apoptosis during repeated exhaustive exercise by enhancing FOXO3a phosphorylation via Akt and SIRT1 activation.