Protective Effects Of Taurine On Heat Stress Induced Injury Of Aortic Endothelial Cells In Broilers

Heat stress is an environmental factor that causes severe economic loss to the current intensive breeding industry,makes the huge impact on the long-term development of livestock and poultry industry.Many animal experiments confirmed that heat stress is a major cause of heat stroke death which dues to large range damage to endoehelial cells.The previous studies have found that taurine has cytoprotective effect,however,the protective effect of taurine on endothelial cells injury and apoptosis induced by heat stress is not clear.So,in this study,we investigated the effects of taurine on endothelial cells injury and apoptosis in broilers under heat stress.In order to provide a theoretical basis for the treatment or mitigation of heat stress related diseases in broilers.The test selected 1 Od healthy broilers and adopted tissue culture method to culture primary aortic endothelial cells of broiler.After immunohistochemical identification with Ⅷfactors related antigen kit,used the 3-5 generation cells that in logarithmic growth phase for the subsequent test.Endothelial cells were randomly divided into five groups:normal control(C)group,heat stress(HS)group,heat stress+low concentration Tau(HS+LTau)group,heat stress+medium concentration Tau(HS+MTau)group and heat stress+high concentration Tau(HS+HTau)group.Each group was cultured in cell incubator(37 ℃,5%CO2)for 24h,then except the cells in normal group were cultured in 37℃,5%CO2 cell incubator,the other four group cells were put in 43 ℃ thermostatic water bath for heat stress treatment 6h,simultaneously.Backed to the cell incubator for rewarming culture 1h,then collected the cells and culture supernatant to detect the indexes.The results are as follows:1)Effects of taurine on activity and apoptosis rate of aortic endothelial cells in broilers under heat stress:Via the MTT colorimetric assay and AO/EB staining observation,in HS group,the activity of aortic endothelial cells is decreased and the apoptosis rate is increased.The relative survival rate of endothelial cells cultured with Tau is significantly higher than that in HS group(P<0.05),the apoptosis rate of endothelial cells cultured with Tau is significantly lower than that in HS group(P<0.05).In combination with the MTT and AO/EB analysis results,it shows that taurine has obvious inhibitory effect for the decreased activity and increased apoptosis rate of endothelial cells which induced by heat stress.Among them,adding 40mmol/L Tau shows the better results.2)Effects of taurine on oxidative damage of aortic endothelial cells under heat stress:Compare with C group,the LDH activity and MDA content of HS group are significantly higher(P<0.01),In the antioxidant system,compare with C group,T-SOD activity,GSH-Px activity and T-AOC of endothelial cells in HS group are significantly lower(P<0.01),and after adding taurine,the LDH activity and MDA content in endothelial cells cultured with Tau are significantly lower than that in HS group(P<0.05),the activity of T-SOD,GSH-Px and T-AOC in endothelial cells cultured with Tau are significantly higher than that in HS group(P<0.05).All results show that,HS leads to the decrease of antioxidant capacity in endothelial cells which induced endothelial cells in a serious oxidative damage condition,while administered Tau could decrease the activity of LDH and the content of MDA in endothelial cells,increase the activity of antioxidant enzymes SOD,GSH-Px and T-AOC,inhibit oxidative stress and enhance antioxidant capacity of endothelial cells to improve the effect of oxidative damage.Among them,adding 40mmol/L Tau shows the better results.3)Effects of taurine on apoptosis related genes and proteins in aortic endothelial cells of broilers under heat stress:After heat stress,compared with the C group,the gene and protein expression levels of apoptosis promoting factors,such as Bax,Caspase-9,Caspase-3,Cyt-c and P53 in endothelial cells of HS group are significantly increased(P<0.05),the gene and protein expression levels of anti-apoptotic factor Bcl-2 in endothelial cells of HS group is significantly lower than that in C group(P<0.05),After administered Tau.the gene and protein expression level of Bcl-2 in endothelial cells is higher than that in HS group(P<0.05),the gene and protein expression levels of apoptosis promoting factors,Bax,Caspase-9,Caspase-3,Cyt-c and P53 in endothelial cells are significantly lower than that in HS group(P<0.05).Analysis of the gene and protein expression level,comprehensively,HS induced high expression of pro-apoptotic genes and proteins,and inhibited the expression of anti-apoptotic gene and protein,caused huge apoptosis of endothelial cells.While administered Tau can significantly reverse these changes,taurine can increase the expression of anti-apoptotic factor,Bcl-2,decrease the expression of pro-apoptotic factors Bax,Caspase-9,Caspase-3,Cyt-c and P53 to inhibit mitochondrial mediated apoptosis of endothelial cells and play an anti-apoptotic effect.Among them,the effect of 40mmol/L Tau on HS induced apoptosis of endothelial cells is better.In summary,adding a certain concentration of Tau can enhance the antioxidant capacity of endothelial cells,inhibit the injury of aortic endothelial cells.Tau may play an important role in the protection of endothelial cells injury by inhibiting the decrease of antioxidant capacity and the activation of mitochondria mediated apoptosis pathway which induced by heat stress.Overall,the effect of adding with the final concentration of 40mmol/L Tau is better.