Objective  To investigate the function of melatonin (MEL) on liver transplantation by detecting the effect of MEL on glucose regulated protein-78 (GRP-78) and CCAAT enhancer-binding protein homologous protein (CHOP) involved in the endoplasmic reticulum stress (ERS) pathways in livers of rats with liver transplantation.

  Methods  The rat orthotopic liver transplantation model was established by using'magnetic-loop method'. Male SD rats were randomized into 3 groups: the sham operation group (Sham group), the orthotopic liver transplantation group (OLT group) and the orthotopic liver transplantation+MEL treatment group (OLT+MEL group), 8 rats in each group. Serum sample and liver sample were collected at 24 h after operation. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected. Liver tissues were stained with hematoxylin-eosin (HE) and pathological changes of liver tissues of each group were observed. The messenger ribonucleic acid (mRNA) and protein expression levels of GRP-78 and CHOP were detected by polymerase chain reaction and Western blot.

  Results  Compared with the Sham group, the serum ALT and AST of the OLT group increased significantly (both in P < 0.01), liver tissues injury was serious, and mRNA and protein expression levels of GRP-78 and CHOP increased significantly (all in P < 0.01). Compared with the OLT group, ALT and AST of the OLT+MEL group decreased significantly (both in P < 0.05), liver tissues injury was alleviated, and mRNA and protein expression levels of GRP-78 and CHOP decreased significantly (all in P < 0.05).

  Conclusions  MEL may reduce mRNA and protein expression levels of GRP-78 and CHOP involved in the ERS pathways of transplant liver, which may be one of its mechanisms to alleviate liver injury after liver transplantation.