Leptin increases mitotic index and regeneration ratio in hepatectomized rats

BACKGROUND The aim of this study was to evaluate the potential effect of intraperitoneal administration of leptin on the hepatic regeneration and the mitotic index. MATERIAL AND METHODS 56 Sprague-Dawley rats were divided into 7 groups each containing 8 rats. Group 1 was evaluated as the sham group and no surgical procedure was performed on animals. The rats in groups 2, 3, and 4 (named C24, C48, C72, respectively) were given intraperitoneal injection of 2 ml/kg normal saline 60 minutes before the surgical procedure consisting of laparotomy and 70% hepatectomy. These groups were used as controls at 24, 48, and 72 hours. The rats in groups 5, 6, and 7 (named L24, L48, and L72, respectively) were given intraperitoneal injection of 20 µg/kg doses of recombinant mouse leptin 60 minutes before the same surgical procedure. These groups were evaluated as the experiment groups at 24, 48, and 72 hours. Blood samples were collected for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) and the remaining tissue samples were obtained for liver histopathology, regeneration rate, and mitotic index (MI). The weights of the remaining livers were also noted. RESULTS The values of AST and ALT were higher in the groups that were administered leptin and they had significantly higher mitotic index than the other groups. Leptin also significantly increased the regeneration ratio as compared to the control group. The weights of the remaining livers were also higher in the leptin groups. CONCLUSIONS Intraperitoneal administration of leptin was observed to increase liver regeneration and mitotic rate in 70% hepatectomized rats.