Protective effects of EGCG on heat stress-induced apoptosis in porcine skeletal muscle satellite cells

【Objective】 This study aimed to investigate the effects and mechanisms of epigallocatechin gallate（EGCG） on apoptosis of porcine skeletal muscle satellite cells induced by heat stress，providing theoretical reference for alleviating heat stress responses and promoting muscle growth in pigs. 【Method】 A heat stress model of porcine skeletal muscle satellite cells was established by treating cells at 41.5°C for 2 d. The effects of heat stress and EGCG on cell growth level were assessed using the CCK-8 assay. Hoechst 33258 staining and flow cytometry were used to detect effects of heat stress and EGCG on cell apoptosis levels. Followed by real-time fluorescence quantitative PCR to measure the relative expression levels of Bcl-2，BAX，Caspase-3，Caspase-9 and Cytc genes，exploring the effects of EGCG on apoptosis related gene expression under heat stress. Western blotting was performed to detect the relative expression levels of Bcl-2 and BAX proteins and the BAX/Bcl-2 ratio，investigating the effects of EGCG on apoptosis related protein expression under heat stress. 【Result】 Treatment at 41.5°C for 2 d extremely significantly decreased cell growth level（P<0.01，the same below）and extremely significantly increased apoptosis rate. Heat stress significantly increased the relative expression of Caspase-3 and Cytc genes and BAX protein（P<0.05，the same below）and extremely significantly elevated the relative expression of BAX and Caspase-9 genes，while extremely significantly reduced the relative expression of Bcl-2 gene and significantly reduced the relative expression of Bcl-2 protein. EGCG alleviated the decrease in cell growth level and the increase in apoptosis level of porcine skeletal muscle satellite cells induced by heat stress，reduced the relative expression of pro-apoptotic genes（BAX，Caspase-3，Caspase-9 and Cytc）and BAX protein，and increased the relative expression of the anti-apoptotic gene Bcl-2 and Bcl-2 protein. 【Conclusion】 EGCG mitigates the decline in growth level of porcine skeletal muscle satellite cells induced by heat stress，and alleviates apoptosis by regulating the relative expression of anti- and pro-apoptotic genes and proteins，including Bcl-2，BAX，Caspase-3，Caspase-9 and Cytc.