ABSTRACT
Objective:To investigate the effect of rapamycin on hepatic ischemia-reperfusion injury (HIRI) in Sprague Dawley (SD) rats and its underlying mechanism.Methods:Forty-eight specific pathogen-free SD male rats with the body weight of 180-200 g and the age of 4-8 weeks were randomly divided into 3 groups, 16 rats each group. In the rapamycin group, the rats were injected with rapamycin intraperitoneally everyday lasting for 3 days before the surgery, and in the model group and the sham group, the rats were injected with normal saline intraperitoneally. The HIRI model was performed in the rapamycin group and the model group. Serum of 8 rats was randomly harvested from each group at 2 h and 24 h after the surgery and was used to detect level of alanine aminotransferase(ALT), total bilirubin, and lactate dehydrogenase. At the meantime, liver tissues were collected for HE staining, and enzyme-linked immunosorbent assay of superoxide dismutase(SOD), glutathione, hexokinase 2, phosphofructokinase 1(PFK1), and adenosine triphosphate. Polymerase chain reaction and Western blots were used to determine the levels of mammalian target of rapamycin(mTOR), ribosomal protein S6 kinase 1(S6K1), and protein kinase B and their phosphorylation levels respectively.Results:Two hours post the surgery, the serum level of ALT(150.9±18.7) U/L, total bilirubin(5.15±0.69) μmol/L, and lactate dehydrogenase(9 547±365) U/L were higher in the model group than sham group (42.4±10.7) U/L, (2.48±0.24) μmol/L, (4 424±376) U/L and rapamycin group (87.7±11.2) U/L, (3.09±0.12) μmol/L, (8 268±264) U/L, and all differences were statistically significant (all P<0.05). HE staining and serum assay showed that the lesion of liver tissuesand of liver function were damaged in the model group, and mitigated in the rapamycin group at 2h and 24h after the surgery. At 2h and 24h after the surgery, liver SOD, glutathione, hexokinase 2, PFK1, and adenosine triphosphate in the model group were lower than those in the sham group and the rapamycin group, and all differences were statistically significant (all P<0.05). The relative levels of mTOR, S6K1, and their phosphorylation level in the model group were higher than those in the sham group and the rapamycin group at 2 h and 24 h after the surgery, but the relative levels of protein kinase B and phosphorylated protein kinase B were lower than those in the sham group and the rapamycin group, and all differences were statistically significant (all P<0.05). Conclusions:Rapamycin improves glucose metabolism and reduces oxidative stress via upregulating the phosphorylated protein kinase B through inhibition of mTOR signaling pathway, thus alleviates HIRI in rats.