Shenfu injection prevents sepsis-induced myocardial injury by inhibiting mitochondrial apoptosis

Shenfu injection (SFI) is a well-known Chinese herbal medicine widely used in the treatment of septic shock in China.The aims of this study are to investigate the protective effects of SFI on sepsis-induced myocardial injury in mice and to identify the underlying mechanism of action.Seventy-two male C57/B6J mice (5-6 weeks old) were randomly divided into five groups: control (NC), sham sepsis (sham), sepsis (Lipopolysaccharide- LPS), sepsis treated with a low dose SFI, and sepsis treated with a high dose SFI. Sepsis was induced in mice by intraperitoneal injection of LPS. Myocardial tissue samples were collected from different groups at 6 h, 12 h, and 24 h post-LPS injection. Myocardial injury was examined using hematoxylin-eosin (HE) and TUNEL staining. Western-blot analysis was performed to determine the protein expression of B-cell lymphoma 2 (Bcl-2), BH3 interacting-domain death agonist (Bid), truncated-Bid (t-Bid) and caspase-9 in all the groups. Moreover, the structural changes in the mitochondria of cardiomyocytes were also observed by transmission electron microscopy.HE staining revealed structural damage, local necrosis, interstitial edema, inflammatory cell infiltration and vacuolar changes in the myocardial tissue in the sepsis (LPS) group; almost intact myocardial tissue was observed in the high dose SFI group with improvements in interstitial edema and inflammatory cell infiltration. We observed that LPS-induced cardiomyocyte apoptosis was significantly improved with high dose SFI as compared with sepsis (LPS) group (P ˂ 0.05). LPS was found to decrease the protein expression of Bcl-2 and increase the level of Bid, t-Bid and caspase-9. Treatment with SFI significantly increased the Bcl-2 protein expression (P ˂ 0.05) and decreased the protein expression of Bid, t-Bid and caspase-9 as compared with LPS group (P ˂ 0.05). Markedly swollen myocardial mitochondria with partial vacuolation were observed in LPS treated mice while SFI treatment was found to significantly improve the LPS-induced morphological damage of the mitochondria.In conclusion, we demonstrate that SFI protects against sepsis-induced myocardial injury in mice through the suppression of myocardial apoptosis. It upregulates the protein expression of Bcl-2 and downregulates the protein expression of Bid, t-Bid and caspase-9, and alleviates sepsis-induced mitochondrial damage.