Expression of endogenous AcSDKP and its precursor thymosin beta 4 in early stage of liver fibrosis induced by carbon tetrachloride in rats

Objective To study the physiological levels and expression of endogenous AcSDKP and its precursor thymosin beta 4 in early liver fibrosis induced by carbon tetrachloride(CCl4) in rats.Methods The rat model of liver fibrosis was induced through subcutaneous injection of CCl4 for 2 weeks and 6 weeks.Liver function was detected and histological appearance was examined by HE staining.Real-time PCR(RT-PCR) was used to quantify expression of AcSDKP's precursor thymosin beta 4(Tβ4) and non-specific thymosin beta 10(Tβ10) mRNA.Enzyme immunoassay was used to determine endogenous AcSDKP in liver homogenate.Results CCl4 injection caused severe liver damages and liver fibrosis at 2 weeks and 6 weeks.As shown by RT-PCR,Tβ4 increased by 0.8-fold(P=0.012) and 4.9-fold (P=0.003) at 2 weeks and 6 weeks respectively compared to corresponding control,but Tβ10 unchanged.In normal rats,the endogenous AcSDKP in the liver were(3.77±0.29) nmol/g and(4.10±1.20) nmol/g at 2 weeks(body weight 259 g) and 6 weeks(body weight 349 g) respectively and it did not statistically differ between the two time points.However,AcSDKP significantly decreased by 28%(P=0.025) and 33%(P=0.042) at 2 weeks and 6 weeks respectively compared to corresponding control.Conclusion In CCl4-induced early liver fibrosis,the AcSDKP precursor Tβ4 expression is significantly elevated in contrast to markedly decreased endogenous AcSDKP,it suggests that the catabolish of endogenous AcSDKP accelerates.The result suggests that inefficiency of endogenous AcSDKP may play an important role in early development of liver fibrosis.