The role of the spleen, platelets, and plasma hepatocyte growth factor activity on hepatic regeneration in rats.

Abstract

Hepatocyte growth factor (HGF) is a humoral factor that may act as a trigger for hepatic regeneration. In this study, changes in the plasma HGF activity on hepatic regeneration in a splenectomized condition were measured for the first time, while the role of the spleen and platelets on hepatic regeneration were also carefully evaluated. Seventy-five male Wistar rats were classified into three groups: group A consisted of rats who underwent a sham operation and a partial hepatectomy; group B consisted of those who underwent a splenectomy and partial hepatectomy; and group C consisted of those who underwent a splenectomy, partial hepatectomy, and were administered an antiplatelet agent. At 24 hours after partial hepatectomy, the weights of the livers of the rats in groups B and C were significantly greater than those of group A, while the labeling index of group C was significantly higher than that of group A and also tended to be higher than that of group B. Regarding the number of platelets, the transient increase in group A occurred earlier than that of either group B or C. The plasma HGF activities also showed a transient increase and the maximum levels were reached at 24 hours in group A, six hours in group B, and 12 hours in group C. It is suggested that the spleen plays an inhibitory role in hepatic regeneration. In the early stage of hepatic regeneration, platelets possibly control HGF induction, while in the following stage, a possible feedback mechanism is also postulated to exist.