[Effects of scutellarin benzyl ester on the expressions of Bcl-2 and Bax in cardiomyocytes injured by acute hypoxia].

Objective: To investigate the effects of scutellarin benzyl ester on the expressions of Bcl-2 and Bax in cardiomyocytes after acute injury of hypoxia.

Methods: Cardiomyocytes harvested from neonatal Sprague-Dawley (SD) rats were cultured for 4 days. The cells of the primary culture were assigned randomly to five groups: control group, hypoxia model group (acute hypoxic injury was induced by exposing cells to anoxic condition with 95%N₂ and 5%CO₂) and high, moderate and low dose of scutellarin benzyl ester groups (pretreated with 100, 50 and 25 μmol/L scutellarin benzyl ester before hypoxia) with 6 wells in each group. After hypoxic injury for 6 hours, the activity of lactate dehydrogenase (LDH) and content of nitric oxide (NO) in media were measured by biochemical methods. The mRNA and protein expressions of Bcl-2 and Bax were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting, respectively.

Results: After hypoxic injury, comparing with those in control group, the leakage of LDH (U/L) in hypoxia model group increased (288.10 ± 30.69 vs. 78.75 ± 12.85) and the release of NO (μmol/L) decreased (9.02 ± 1.55 vs. 24.11 ± 2.04, both P<0.01). However, high, moderate and low dose of scutellarin benzyl ester could significantly reduce the LDH leakage (64.19 ± 22.90, 101.35 ± 22.71, 141.34 ± 23.08) and high and moderate dose of scutellarin benzyl ester could increase the NO release (14.45 ± 3.57, 12.38 ± 1.57), with remarkably significant statistical difference (all P<0.01). After hypoxic injury, comparing with those in control group, the mRNA and protein expressions of Bcl-2 in hypoxia model group decreased (Bcl-2 mRNA: 0.544 ± 0.108 vs. 0.837 ± 0.213, Bcl-2 protein: 0.813 ± 0.041 vs. 0.917 ± 0.046), and the mRNA and protein expressions of Bax in hypoxia model group increased (Bax mRNA: 0.918 ± 0.228 vs. 0.493 ± 0.123, Bax protein: 0.623 ± 0.031 vs. 0.490 ± 0.025, all P<0.01). Comparing with those in hypoxia model group, high and moderate dose of scutellarin benzyl ester could up-regulate the mRNA and protein expressions of Bcl-2 (Bcl-2 mRNA: 0.708 ± 0.123, 0.604 ± 0.116 vs. 0.544 ± 0.108, Bcl-2 protein: 0.887 ± 0.044, 0.850 ± 0.043 vs. 0.813 ± 0.041) and down-regulate the mRNA and protein expressions of Bax (Bax mRNA: 0.614 ± 0.136, 0.728 ± 0.152 vs. 0.918 ±0.228, Bax protein: 0.518 ± 0.026, 0.547 ± 0.027 vs. 0.623 ± 0.031, all P<0.01). However, there was no statistical difference in the mRNA and protein expressions of Bcl-2 and Bax between hypoxia model group and low dose of scutellarin benzyl ester group (Bcl-2 mRNA 0.551 ± 0.112, Bcl-2 protein 0.823 ± 0.041; Bax mRNA 0.857 ± 0.218, Bax protein 0.617 ± 0.031).

Conclusion: Scutellarin benzyl ester has a protective effect on acute myocardial hypoxic injury, and the mechanism is probably related to the regulation of the expressions of Bcl-2 and Bax.