Protective Effects Of Hawthorn Leaves Flavonoids On Lipotoxicitic Damage Of Islet βTC3Cells Induced By Free Fatty Acid

Hawthorn leaves flavonoids（HLF）is the main active substance extractedfrom the leaves of hawthorn. In recent years a large number of studies showedthat HLF benefited the regulation of lipid metabolism. Research also showedthat HLF could improve the hyperinsulinemia of rats. However, it hadn’t beenreported that whether HLF could protect the islet cell against the damage of thelipotoxicity. So the protecive effects of HLF on lipotoxicitic damage in isletβTC3cells induced by free fatty acid was observed and analyzed in this study.OBJECTIVE:To observe the protective concentration and treat time of HLF from thedamage induced by PA（palmic acid）and the protective effects of HLF to theability of insulin secretion of islet βTC3cell stimulted by different concentrationglucose and PA. METHOND:It was observed with MTT that the damage of lipid toxicity to islet βTC3cell induced by the PA and the HLF protective effects. The islet βTC3cells weredivided into the normal group, BSA group, PA group, HLF+PA group. HLF wasused as10,30,50,100μg/ml for24hours, so that the effective concentrationcould be screened. With above result,50μg/ml HLF was selected to be usedtogether with PA for24、48、72hours as well to observe the best treat time ofHLF. After that, cells apoptosis, induced by0.4mmol/L PA and PA together with50μg/ml HLF, was observed by TUNEL method. Then we calculated the cellapoptosis indices. Next, Radioimmunoassay was used to analyze the ability ofthe islet βTC3cell secreting insulin after treated by glucose of5mmol/L and22.4mmol/L within different groups. Finally, The expression of Bcl-2/Baxprotein was detected by Western Blot method.RESULTS:1．The results obtained from MTT indicated that the10-100μg/ml HLFcould effectively protect the islet βTC3cells from the damage of0.4mmol/L PA,and the cell viability was higher in every HLF and PA concentration groups thanthat in PA group (P<0.05). On the other hand, the treatment of the50μg/ml HLFtogether with PA to the islet βTC3cells for24h was demonstrated to be the mosteffective in cell protection.2．The results of TUNEL showed that the apoptosis rate of the50μg/mlHLF and0.4mmol/L PA group was lower than that of the PA group（P<0.05）.3. After stimulation of the glucose concentration of5mmol/l and22.4mmol/l, the islet βTC3cells treated by the50μg/ml HLF together with PA,secreted much more insulin than the islet βTC3cells treated by PA;and whenstimulated by the glucose concentration of22.4mmol/l, every group showedweaker ability of secreting insulin than that of5mmol/l.4. The results of Western Blot showed PA decreased the expression of anti-apoptosis protein Bcl-2, but increased the expression of pro-apoptosisprotein Bax. However, HLF increased the expression of anti-apoptosis proteinBcl-2, and decreased the expression of pro-apoptosis protein Bax. The resultsalso showed Bcl-2/Bax ratio of the HLF group was higer than the PA group（P＜0.05）.CONCLUSION:When the islet βTC3cells treated by HLF and PA together, the trend of cellactivity reduction was decreased as well as the apoptosis., which maybecontributed to the mechanism of apotosis protein Bcl-2/Bax. We also observedthat HLF could decrease the reduction of islet βTC3cells’ability of secretinginsulin induced by PA.But the specific mechanism needed to be further study.