Objective: To investigate the inhibitory effect of salidroside (Sal) on pulmonary microvascular endothelial cell (HPMEC) apoptosis induced by simulated microgravity and its mechanism.
Methods: Human pulmonary microvascular endothelial cells cultured in vitro were divided into control group, clinorotation group and clinorotation+Sal pretreatment groups. Microgravity was simulated by clinorotation. The apoptotic rate of HPMECs was detected by flow cytometry using Annexin V-FITC staining, and the expressions of bcl-2, bax, and caspase-3 at the mRNA and protein levels were determined by real-time PCR and Western blotting, respectively.
Results: A 72-h clinorotation significantly induced apoptosis in HPMECs. Real-time PCR results demonstrated a significantly lowered bcl-2 but increased bax and caspase-3 mRNA expressions in clinorotation group as compared with those in the control group. Western blotting showed that clinorotation inhibited the protein expressions of PI3K and p-AKT and increased caspase-3 protein expression. Salidroside significantly inhibited the cell apoptosis, reversed the expressions of Bcl-2 and Bax, and attenuated the decrease in the protein expression of PI3K and phosphorylation level of AKT. Salidroside also antagonized the activation of caspase-3.
Conclusion: PI3K/AKT pathway and caspase 3 are involved in the apoptosis of HPMVECs induced by clinorotation, and the effect of clinorotation can be reversed by salidroside, suggesting the potential value of salidroside for application in spaceflight.