Protective Effects And Mechanism Of Polypeptides From Chlamys Farreri On Thymocytes Damaged By H₂O₂

AIM The polypeptides(PCF, Molicular weight: 912) was isolated from Chlamys farreriusing enzyme engineering technique. We established the oxidative models of thymocytescaused by H2O2 to study the protective effects of PCF on thymocytes from the Qunming micedamaged by 12.5μM H2O2. MATHODS The cells were randomly divided into six groups:control group, H2O2 model group, H2O2+0.5%PCF group, H2O2+0.25%PCF group,H2O2+0.125%PCF group and H2O2+0.1%Vc group. The concentration of SOD, GSH-Px,ROS, MDA, T-AOC, A-ASC and the cells' viability were determined by biochemical andMTT methods respectively. The free calcium, mitochondria memberine potential and the rateof apoptosis on thymocytes were tested using flow cytometry(FCM). The expressions of P53,Bax and Bcl-2 proteins were examined by immunocytochemical technic. Also we determinedthe p21WAF1mRNA, p38mRNA expressions through the technique of in situ hybridation. Theultrastructure of the cells was observed through electron microscope. RESULTS The resultsindicated that PCF could enhance the activities of GSH-Px, SOD, A-ASC, T-AOC and ODvalues in cells. The concentration of cellular free calcium was decreased by PCF. PCFdecreased the amounts of ROS, MDA and the rates of apoptosis in cells. It also raised theexpression of Bcl-2 gene and decreased the expression of P53, Bax. The Mrna expression ofp21 and p38 decreased in PCF groups. The ultrastructural damages of the cells were inhibitedby PCF. The results showed that the observed indexes of the PCF groups are significantlydifferent compared with model group(P<0.05). CONCLUSION PCF has the protective effectson damages of thymocytes caused by the oxidation of H2O2. The mechanisms might berelated to inhibiting of the amount of ROS and raising the expressioin of Bcl-2 gene,increasing anti-oxidative enzymes in cells and inhibiting the lipid peroxide.