Protective effects of high-density lipoprotein on mice cardiomyocytes induced by oxygen and glucose deprivation through Akt signaling pathway

Abstract

To investigate the protective effect of high-density lipoprotein (HDL) on the mice cardiac myocytes induced by oxygen and glucose deprivation (OGD). Cardiac cells of primary scavenger receptor-B1 knockout mice (SR-B1-/-) and normal C57 mice (SR-B1+/+) were obtained by protease digestion and differential adhesion method. (1) The two kinds of cells were divided into normal control group (Con group), OGD group, OGD+HDL group. Propidium iodide (PI) staining were used to determine the necrosis of cardiac myocytes. (2) SR-B1+/+ cardiac cells were divided into Con group, OGD group, OGD+HDL group, and phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) inhibitor LY294002 group. PI staining were used to determine the necrosis of cardiac myocytes. TUNEL staining was used to determine the cell apoptosis. The kit was used to determine the contents of MB isoenzyme of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) in the culture medium supernatant. The expressions of SR-B1 and Akt protein were determined by Western Blot. (1) In SR-B1+/+ cardiomyocytes, HDL could inhibit cell necrosis induced by OGD. There was no protective effect of HDL on OGD in the SR-B1-/- cardiomyocytes. (2) The study of SR-B1+/+ cells was showed that compared with Con group, necrotic cells were significantly increased and cell activity were significantly decreased, the cell viability were significantly decreased, the contents of LDH and CK-MB in supernatant were significantly increased, the expressions of phosphorylated Akt (p-Akt) and SR-B1 were significantly decreased in OGD group. Compared with OGD group, the number of necrotic cells in the OGD+HDL group was significantly decreased [PI positive cells rate: (26.71±5.94)% vs. (64.24±18.34)%], the cell activity was significantly increased [(63.84±6.95)% vs. (26.71±5.13)%], the contents of LDH and CK-MB in supernatant were significantly decreased [LDH (U/L): 896.3±161.5 vs. 1 568.3±243.5, CK-MB (U/L): 304.3±72.9 vs. 583.6±81.6], the expressions of p-Akt and SR-B1 were significantly increased (p-Akt/t-Akt: 0.84±0.13 vs. 0.18±0.06, SR-B1/β-actin: 1.23±0.19 vs. 0.09±0.02), with statistically significant differences (all P < 0.05). Compared with OGD+HDL group, necrotic cells in LY294002 group were increased, cell activity was decreased, LDH and CK-MB contents in supernatant were increased, p-Akt and SR-B1 expressions were decreased; there was no statistical difference between LY294002 group and OGD group. There was no significant difference in cell apoptosis among the 4 groups. HDL has protective effect on the mice myocardial cells. The mechanism may be related with the up regulation of the expression of SR-B1 protein by the activation of PI3K/Akt pathway.