Sodium tanshinone IIA sulfate protects myocardium against paraquat-induced toxicity through activating the Nrf2 signaling pathway in rats

Objective: To investigate the therapeutic effect and mechanism of sodium tanshinone IIA sulfate (STS) on paraquat (PQ)-induced myocardial injuries in a rat model. Methods: Healthy adult Sprague Dawley rats were randomly divided into normal control, PQ, and PQ + STS groups. PQ group was given a single intragastric administration of PQ (80 mg/kg). PQ + STS group was intraperitoneally injected with STS (1 ml/kg) at 30 min following PQ exposure. Rats in control and PQ groups were injected with equal amount of saline. After 12, 24, 48, and 72 h, rats were killed, and the apoptosis of myocardial cells was detected. Myocardial expression of Bax and Bcl-2 was measured. The activity of the nuclear erythroid 2-related factor 2 (Nrf2) pathway was assessed by Western blot. Results: The apoptotic cells in PQ group were significantly increased in a time-dependent manner compared with the control group (p < 0.01). The rats in PQ group exhibited significantly lower Bcl-2 expression, but notably higher Bax expression at 12, 24, 48, and 72 h after PQ exposure (p < 0.05 or 0.01). STS intervention markedly reduced the proportion of apoptotic myocardial cells, increased Bcl-2 expression, and decreased Bax expression at 24, 48, and 72 h after treatment (p < 0.05 or 0.01). The expression of phosphorylated Nrf2 and heme oxygenase 1 in PQ + STS group was significantly increased compared with PQ and control groups (p < 0.05 or 0.01). Conclusion: STS effectively inhibits PQ-induced myocardial cell apoptosis in rats via modulating the Nrf2 pathway, suggesting its potential as a promising therapeutic agent for PQ-induced myocardium damage.