[Post-ischemic treatment of nalmefene hydrochloride attenuated lung ischemia-reperfusion injury in rats via the Sirt1/Nrf2/HO-1 pathway with inhibition of ferroptosis].

Objective: To study the effect and mechanism of post-ischemic treatment of nalmefene in alleviating the lung ischemia-reperfusion injury by inhibiting ferroptosis through activation of the Sirt 1/Nrf 2/HO-1 axis. Methods: A total of 60 rats were randomly divided into six groups equally (n=10): the sham group, the model group(I/R), the nalmefene group, the nalmefene+EX527 group, the nalmefene+ML385 group, the nalmefene+Fe-citrate group (nalmefene+Fe group). The sham group without drug treatment was not treated with ischemia-reperfusion. The pulmonary ischemia-reperfusion model was established by occlusion of the left pulmonary hilum in the model group without drug treatment. After ischemic treatment, the nalmefene group was injected with nalmefene (15 µg/kg) via the tail vein at 5 minutes before reperfusion. The nalmefene+EX527 group, the nalmefene+ML385 group, and the nalmefene+Fe group were injected intraperitoneally with EX527 (5 mg/kg), ML385 (30 mg/kg), Fe-citrate(15 mg/kg), respectively, 2 h before moulding and then injected with nalmefene (15 µg/kg) via the tail vein at 5 minutes before reperfusion. All rats were sacrificed three hours after reperfusion, and the specimens from the upper lobe of the left lung tissue were preserved. The degree of lung tissue injury and the wet/dry weight ratio were assessed in each group of rats. Fe 2+, MDA, TNF-α, and IL-6 content, GSH activity and the expression levels of Sirt1, Nrf2, HO-1, ACSL4 and GPX4 were determined. Results: Compared with the sham group, the wet/dry weight ratio, lung tissue injury score, ACSL 4 expression level, Fe 2+, TNF-α, IL-6 and MDA content, Sirt 1, Nrf 2, HO-1 messenger RNA and protein expression levels were significantly increased (P<0.01), while GPX 4 expression level and GSH activity were significantly decreased in the model group (P<0.01). Compared with the model group, wet/dry weight ratio, lung tissue injury score, ACSL 4 expression level, Fe 2+, TNF-α, IL-6, and MDA content decreased significantly (P<0.01), Nrf 2, HO-1 messenger RNA and protein, GPX 4 expression, and GSH activity were significantly increased in the nalmefene group and the nalmefene+EX527 group (P<0.01). Sirt 1 messenger RNA and protein expression increased significantly in the nalmefene (P<0.01) and the nalmefene+EX527 groups (P>0.05). In the nalmefene+ML385 group, the wet/dry weight ratio, lung tissue injury score, TNF-α and IL-6 content were decreased significantly (P<0.01), while Sirt 1 messenger RNA and protein expression levels were significantly increased (P<0.01), but there were no significant changes in Nrf 2, HO-1 messenger RNA and protein expression levels, ACSL 4 and GPX 4 expression levels, Fe 2+, MDA content, and GSH activity (P>0.05). In the nalmefene+Fe group, wet/dry weight ratio, lung-injury score, TNF-α, IL-6, MDA content were decreased significantly (P<0.01), messenger RNA and protein expression levels of Sirt 1, Nrf 2, HO-1, and GSH activity were increased significantly (P<0.01), but there were no significant changes in Fe 2+content, ACSL 4 and GPX 4 expression levels (P>0.05). Compared with the nalmefene group, in the nalmefene+EX527 group, the nalmefene+ML385 group and the nalmefene+Fe group, wet/dry weight ratio, lung tissue damage score, ACSL 4 expression level, TNF-α, IL-6 and MDA content were significantly increased (P<0.01), the expression level of GPX 4 and GSH activity were significantly decreased (P<0.01). The expression levels of Sirt 1, Nrf 2, HO-1 messenger RNA and protein were significantly decreased in the nalmefene+EX527 group (P<0.01). The expression levels of Nrf 2, HO-1 messenger RNA and protein decreased significantly in the namemefene+ML385 group (P<0.01), but there was no significant change in Sirt 1 messenger RNA and protein expression level (P>0.05). Sirt 1, Nrf 2, HO-1 messenger RNA-protein expression levels did not change significantly in the nalmefene+Fe group (P>0.05). Conclusion: Post-ischemic treatment with nalmefene hydrochloride may alleviate pulmonary ischemia-reperfusion injury by inhibiting ferroptosis through activation of the Sirt 1/Nrf 2/HO-1 axis.