Ginsenoside Rb1 Ameliorates Autophagy of Hypoxia Cardiomyocytes from Neonatal Rats via AMP-Activated Protein Kinase Pathway.

OBJECTIVE: To investigate whether ginsenoside-Rb1 (Gs-Rb1) improves the CoCl-induced autophagy of cardiomyocytes via upregulation of adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway. METHODS: Ventricles from 1- to 3-day-old Wistar rats were sequentially digested, separated and incubated in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum for 3 days followed by synchronization. Neonatal rat cardiomyocytes were randomly divided into 7 groups: control group (normal level oxygen), hypoxia group (500 µmol/L CoCl2), Gs-Rb1 group (200 µmol/L Gs-Rb1 + 500 µmol/L CoCl2), Ara A group (500 µmol/L Ara A + 500 µmol/L CoCl2), Ara A+ Gs-Rb1 group (500 µmol/L Ara A + 200 µmol/L Gs-Rb1 + 500 µmol/L CoCl2), AICAR group [1 mmol/L 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) + 500 µmol/L CoCl2], and AICAR+Gs-Rb1 group (1 mmol/L AICAR + 200 µmol/L Gs-Rb1 + 500 µmol/L CoCl2). Cells were treated for 12 h and cell viability was determined by methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and cardiac troponin I (cTnI) levels were detected by enzyme-linked immunosorbent assay (ELISA). AMPK activity was assessed by 2',7'-dichlorofluorescein diacetate (DCFH-DA) ELISA assay. The protein expressions of Atg4B, Atg5, Atg6, Atg7, microtubule-associated protein 1A/1B-light chain 3 (LC3), P62, and active-cathepsin B were measured by Western blot. RESULTS: Gs-Rb1 significantly improved the cell viability of hypoxia cardiomyocytes (P<0.01). However, the viability of hypoxia-treated cardiomyocytes was significantly inhibited by Ara A (P<0.01). Gs-Rb1 increased the AMPK activity of hypoxia-treated cardiomyocytes. The AMPK activity of hypoxia-treated cadiomyocytes was inhibited by Ara A (P<0.01) and was not affected by AICAR =0.983). Gs-Rb1 up-regulated Atg4B, Atg5, Beclin-1, Atg7, LC3B II, the LC3B II/I ratio and cathepsin B activity of hypoxia cardiomyocytes (P<0.05), each of these protein levels was significantly enhanced by Ara A (all P<0.01), but was not affected by AICAR (all P>0.05). Gs-Rb1 significantly down-regulated P62 levels of hypoxic cardiomyocytes (P<0.05). The P62 levels of hypoxic cardiomyocytes were inhibited by Ara A (P<0.05) and were not affected by AICAR (P=0.871). CONCLUSION: Gs-Rb1 may improve the viability of hypoxia cardiomyocytes by ameliorating cell autophagy via the upregulation of AMPK pathway.

Apelin-APJ effects of ginsenoside-Rb1 depending on hypoxia-induced factor 1α in hypoxia neonatal cardiomyocytes.

OBJECTIVE: To investigate whether ginsenoside-Rb1 (Gs-Rb1) inhibits the apoptosis of hypoxia cardiomyocytes by up-regulating apelin-APJ system and whether the system is affected by hypoxia-induced factor 1α (Hif-1α). METHODS: Neonatal rat cardiomyocytes were randomly divided into 6 groups: a control group, a simple CoCl group, a simple Gs-Rb1 group, a CoCl and Gs-Rb1 hypoxia group, a CoCl and 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) group, a CoCl and YC-1 group and a Gs-Rb1 group, in which YC-1 inhibits the synthesis and accelerates the degradation of Hif-1a. The concentration of CoCl, Gs-Rb1 and YC-1 was 500 µmol/L, 200 µmol/L and 5 µmol/L, respectively; the apoptosis ratio was analyzed with a flow cytometer; and apelin, APJ and Hif-1α were assayed with immunocytochemistry, Western blot assays and reverse transcription polymerase chain reaction (RT-PCR). RESULTS: (1) The anti-apoptosis effect of Gs-Rb1 on hypoxia cardiomyocytes was significantly inhibited by YC-1; (2) Hypoxia significantly up-graded the expression of mRNA and protein of apelin; this effect was further reinforced by Gs-Rb1 and significantly inhibited by YC-1; (3) Gs-Rb1 further strengthened the expression of APJ mRNA and APJ proteins once hypoxia occurred, which was significantly inhibited by YC-1; (4) Gs-Rb1 significantly increased the expression of Hif-1α, which was completely abolished by YC-1; (5) There was a negative relationship between AR and apelin (or APJ, including mRNA and protein), a positive correlation between apelin (or APJ) protein and Hif-1a protein, in hypoxia cardiomyocytes. CONCLUSION: The apelin-APJ system plays an important role in the anti-apoptosis effect of Gs-Rb1 on hypoxia neonatal cardiomyocytes, which was partly adjusted by Hif-1α.