Hepatic branch vagotomy can block liver regeneration enhanced by ursodesoxycholic acid in 66% hepatectomized rats

The effect of hepatic branch vagotomy on liver regeneration induced by ursodesoxycholic acid was examined in 66% hepatectomized rats. A standard feeding was obtained from animals with hepatic branch vagotomy, and all rats examined received pair food intake. Liver regeneration was evaluated by the hepatocyte mitotic index. When ursodesoxycholic acid 12.5 mg kg−1 day−1 was administered orally, a significant increase in the mitotic index was observed 2 and 3 days after hepatectomy, and the mitotic index response 2 days after hepatectomy was dose-dependent in the range of 0–25 mg kg−1 day−1. Hepatic branch vagotomy suppressed the mitotic index 2 days after hepatectomy, and the mitotic index increase due to ursodesoxycholic acid was blocked by hepatic branch vagotomy, but not by gastric branch vagotomy. It was also noted that hepatic branch vagotomy or ursodesoxycholic acid or both did not affect serum parameters indicating liver and kidney function. Because ursodesoxycholic acid exists in the bile juice, these results suggest that the hepatic vagus nerve is specifically active with endogenous bile acids in the control of liver regeneration.