Activin and activin receptor expression changes in liver regeneration in rat

Background. This study aimed to investigate regulatory mechanisms of hepatocyte proliferation by comparing liver regeneration of the remnant lobe after 70% partial hepatectomy (PH) and portal vein branch ligation (PBL) in rat. Methods. Expressions of activins beta A, beta C, and beta E and their receptors were investigated after PH and PBL. The proliferating cell nuclear antigen (PCNA) labeling index was used to monitor hepatocyte proliferation. Results. The PCNA labeling index in the regenerative lobe of PBL rats reached a peak at 48 h, a delay of 24 h compared with the remnant lobe in PH rats. In the postoperative early stage, the expression of activin beta A, beta C, and beta E mRNAs was stronger in PBL than PH. At 72 h the expression of activin receptor type IIA mRNA reached a peak in PH but was significantly lower in PBL. Conclusions. Hepatocyte proliferation, and the regulated expression of activins and their receptors, differs during liver regeneration after PH and PBL in the rat. Thus, regulation of activin signaling through receptors is one of the factors determining liver regeneration after PH and PBL. (C) 2005 Elsevier Inc. All rights reserved.