The Effects Of NF-κB On Hepatic Oval Cells And The Possible Regulating Mechanism Of Baicalin In Acute Liver Injury Rats

Hepatic oval cell(HOC) is liver stem cell,with multidirectionaldifferentiation potential.Liver has a strong ability to repair itself,only when itdamaged seriously and hepatocytes proliferation impaired,oval cells areactivated and differentiate into hepatocytes and bile duct cells,participating inthe repair of injuring liver.But excessive proliferation of HOC can producecanceration,it’s necessary to know the mechanism of oval cell proliferationand differentiation for treatment of liver injury. Nuclear factor kappa B(NF-κB)is a important nuclear transcription factor,taking part in hepatic oval cellproliferation regulation,and it could be a target of drugs in liver injurytreatment.Liver injury caused by various reasons， such as hepatitis viruses,alcohol,drugs and toxins，and oxidative stress is the principal mechanism.Many factors participate in this process,such as reactive oxygen species(ROS),Endothelin-1(ET-1),which can activate NF-κB and produce inflammation.Baicalin that belongs to flavonoids is a active component of traditionalChinese medicine radix scutellariae,confirmed to have functions ofantibacterial, antioxidant, anti-inflammatory, scavenging free radicals and soon.Recent studies found that baicalin has protective effect against liverinjury,but its mechanism is still not clear.This study research the effects ofNF-κB on oval cell proliferation and differentiation and the possiblemolecular mechanism of baicalin on oval cell.Objective:By building the oval cell proliferation model of acute liverinjury in rats and intervening with baicalin,exploring the effects ofNF-κB on hepatic oval cells and the possible mechanism of baicalinfor injuring liver.Methods:Healthy adult Sprague–Dawley(SD) rats, male or female, weighing200g±20g，were randomly divided into4groups.The control groupwas given sham operation.Model group rats were given daily15mg/kg of2-acetylaminofluorene（AAF） by gavage for4days,a standard2/3partialhepatectomy （2/3PH）was performed at the5th day,continuing the lavage for5days after surgery. Baicalin low-dose group and high-dose group were dailygiven respectively50mg/kg and100mg/kg of baicalin by lavage whenmodeling until killed.Rats were respectively killed at1d,7d,14d,and21d afterPH in each group,4rats of each time point,serum and liver tissue sampleswere collected.Then observing the pathology morphology of liver byhematoxylin and eosin (H&E) staining;identifying the ultrastructure of hepaticoval cell under electron microscopy;determining the expressions of OV6byusing immunofluorescence technique;determining the expressions of c-kit、AFP、CK19by immunohistochemical staining;determining the expressions ofNF-κB respectively by reverse transcription-polymerase chain reaction(RT-PCR) and Western Blotting;and testing the MDA、H2O2and ET-1ofserum.Result:①Routine pathological microscopy showed a normal liverlobular architecture and cell structure,not found the typical oval cells incontrol group.In model group, hepatic lobule structure was destroyed,degeneration and necrosis of parenchymal cells were found, and hepatic ovalcells were visible.The oval cell number of baicalin intervention group was lessthan the model group at each time point,and the high does group reduced moredramatically.②Observing under the electron microscopy,the oval cells aresmall,about7to10microns in diameter, the nucleus is relatively large, highnuclear/cytoplasmic ratios,and the cytoplasm is rich in free ribosomes but rarein rough endoplasmic reticulum and mitochondria,Tonofilament bundles arevisible.③The expressions of c-kit、OV6、AFP、CK19were no significantchange over time in sham operation group,but they began to increase afterPH,peaked at14th day and decreased at21st day, and there is significancestatistical difference between groups (P<0.05).Compared with the modelgroup,the OV6,c-kit and AFP of baicalin intervention group expressed less （P<0.05） but CK19expressed more（P<0.05）,and the high does groupchanged more obviously(P<0.05).④The expressions of NF-κB also began toincrease after PH,peaked at14th day and decreased at21st day in modelgroup,consistent with the proliferation of oval cells.They reduced in baicalinintervention groups,and the high does group changed more obviously.Thedifference between groups was statistically significant(P<0.05).⑤SerumMDA、 H2O2and ET-1dramatically increased(P<0.05)， however,administration of different doses of baicalin(50,100mg/kg) per dayattenuated the changes，and attenuation of the high does group was moreremarkable(P＜0.05).Conclusion:Proliferation and differentiation of hepatic oval cells relatesto the activation of NF-κB.Baicalin could inhibit oval cells proliferation andinduces them to differentiate into hepatocytes and bile duct cells throughdown-regulating NF-κB signaling pathway,it could be a possible mechanismof baicalin for protecting liver...