Antiproliferative Effects of Bombesin and Neurotensin on Oval Cells in Exprerimental Biliary Obstruction in Rats
S Assimakopoulos, AC Tsamandas, C Georgiou, C Vagianos, CD Scopa. University of Patras, Patras, Greece
Background: Oval cells (OC) are liver stem cells involved in organ's regeneration following diverse types of injury, while their numbers increase in direct proportion with liver injury severity. This study investigates the effect of the neuropeptides bombesin (BBS) and neurotensin (NT) on OC proliferation in the cholestatic rat liver.
Design: Seventy male Wistar rats were randomly divided into 5 groups: controls, sham operated, bile duct ligated (BDL), BDL+BBS (10μg/kg/d), BDL+NT (300μg/kg/d). After 10 days, rats were sacrificed and total bilirubin and ALT levels were determined. Liver tissue samples were evaluated for expression of alpha-fetoprotein (AFP) mRNA (in situ hybridization), CK19 and Ki67 antigen expression (immunohistochemistry) and apoptosis (TUNEL). Cells with morphologic features of OC that were CK19(+) and AFP mRNA(+) were scored in morphometric analysis and their proliferation (Ki67+ OC) was recorded. Also, proliferation, apoptosis were evaluated in hepatocytes and cholangiocytes. Hepatic oxidative stress was estimated on liver homogenates by measurements of lipid peroxidation and glutathione redox state.
Results: The neuropeptides BBS and NT significantly attenuated cholestatic liver injury as evidenced by reduction of ALT activity and hepatic oxidative stress. Both agents exerted similar and cell type-specific effects on OC, hepatocytes and cholangiocytes: (a) as table shows OC proliferation and accumulation in the cholestatic liver was attenuated, (b) hepatocyte proliferation was increased along with a decreased rate of their apoptosis (p<0.001 in each case) and (c) cholangiocyte proliferation was attenuated and their apoptosis was increased (p<0.001 in each case).
|Markers||Control (I)(n=10)||Sham (II)(n=15)||BDL (III)(n=15)||BDL+BBS (IV)(n=15)||BDL+NT (V)(n=15)|