THE ROLE OF THE SPLEEN, PLATELETS, AND PLASMA HEPATOCYTE GROWTH-FACTOR ACTIVITY ON HEPATIC REGENERATION IN RATS

BACKGROUND: Hepatocyte growth factor (HGF) is a humoral factor that ma y act as a trigger for hepatic regeneration. In this study, changes in the plasma HGF activity on hepatic regeneration in a splenectomized c ondition were measured for the first time, while the role of the splee n and platelets on hepatic regeneration were also carefully evaluated. STUDY DESIGN: Seventy-five male Wister rats were classified into thre e groups: group A consisted of rats who underwent a sham operation and a partial hepatectomy; group B consisted of those who underwent a spl enectomy and partial hepatectomy; and group C consisted of those who u nderwent a splenectomy, partial hepatectomy, and were administered an antiplatelet agent. RESULTS: At 24 hours after partial hepatectomy, th e weights of the livers of the rats in groups B and C were significant ly 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 hi gher than that of group B. Regarding the number of platelets, the tran sient 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 g roup B, and 12 hours in group C. CONCLUSIONS: It is suggested that the spleen plays an inhibitory role in hepatic regeneration. In the early stage of hepatic regeneration, platelets possibly control HGF inducti on, while in the following stage, a possible feedback mechanism is als o postulated to exist.