| The oxidative damage of broilers exposed to high levels of relative oxygen species(ROS)caused by oxidative stress can impair the meat quality,which blocks the healthy development of modern broiler industry.It is worth noting that many previous studies investigate the problem of oxidative damage based on one of a variety of stressors that indirectly induce the production of ROS,which results in the precise mechanism of oxidative damage in muscle of broilers remains elusive.The direct way of increasing body ROS levels could provide a new research idea for clarifying the mechanism of oxidative damage.As a highly active ROS in organism,hydrogen peroxide(H2O2)can be generated by almost all oxidative stressors.Taurine has been demonstrated to have antioxidative function.Therefore,the objective of this project is to study the responsive relationship between the change in meat quality and oxidative damage induced by high levels of ROS in muscle of broilers administrated with H2O2.Moreover,we further explore the occurrence rule of apoptosis and autophagy,and the expression regularity of NF-?B signal pathway in both in vivo and in vitro experiments to investigate the mechanism of oxidative damage induced by ROS.Then,we study the soothing effect of taurine on oxidative damage of muscle.We will clarify the molecule mechanism of H2O2-induced oxidative damage and the antioxidative function of taurine.The results will provide an important theoretical basis for alleviating broiler oxidative stress by establishing strategies for scientific management and nutrition regulation in broiler industry.1.Effects of H2O2-injection on growth performance,meat quality and oxidative damage of liver and muscle in broilersExperiment 1:We investigated the change of growth performance of broilers exposed to H2O2 and further explored the occurrence of apoptosis and autophagy,as well as the expression of NF-?B in these signaling pathways in the liver.A total of 320 one-day-old Arbor Acres male broiler chickens were raised on a basal diet and randomly divided into five treatments which were arranged as non-injected treatment(Control),physiological saline(0.75%,1 mL/kg BW)injected treatment(Saline)and 0.74,1.48,or 2.96 mmol/kg BW H2O2-injected treatments(H2O2(0.74),H2O2(1.48)and H2O2(2.96)).The experimental period is 42 d,and all birds in saline and H2O2 treatments were administered the injections on days 16 and 37 of the experiment.The results showed that 1.48 and 2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)body weight gain(BWG)than the control and saline treatments in 22-42 days and 1-42 days post-hatch,whereas the feed/gain ratio(F/G)of H2O2(2.96)treatment in 22-42 days and 1-42 days post-hatch,and F/G of H2O2(1.48)treatment in 1-42 days post-hatch were significantly higher(P<0.05)than the control and saline treatments.pH24h value in the muscle of H2O2(2.96)treatment and pH24h value in the breast muscle of H2O2(i.48)treatment were significantly lower(P<0.05),and drip loss in the thigh muscle and shear force value in the muscle of H2O2(2.96)treatment were significantly higher(P<0.05)than the control and saline treatments.Compared with the control and saline treatments on 21 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)relative weight of liver,total antioxidant capacity(T-AOC)and catalass(CAT)activity in the serum,the activities of total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-Px),total sulfhydryl content in the serum and liver,whereas significantly higher(P<0.05)the contents of advanced oxidative protein products(AOPPs)in serum,the 8-hydroxy-2'-deoxyguanosine(8-OHdG)and malondialdehyde(MDA)in the serum and liver,protein carbonyl content in the liver,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)relative weight of liver,T-AOC and total sulfhydryl content in the serum,T-SOD activity in serum and liver,and GSH-Px activity in the liver,whereas significantly higher(P<0.05)MDA content in the liver.Compared with the control and saline treatments on 21 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)T-AOC,the activities of T-SOD and GSH-Px in the muscle,total sulfhydryl content in the thigh muscle,whereas significantly higher(P<0.05)the contents of protein carbonyl,8-OHdG,AOPPs and MDA in the muscle,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)T-AOC and GSH-Px activity in the thigh muscle,whereas significantly higher(P<0.05)MDA content in the breast muscle.Compared with the control and saline treatments on 42 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)T-AOC and CAT activity in serum,total sulfhydryl content in the serum and liver,the activities of T-SOD and GSH-Px,whereas significantly higher(P<0.05)relative weight of pancreas,the contents of 8-OHdG in serum,AOPPs and MDA in the serum and liver,ROS formation,protein canbonyl content in the liver,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)T-AOC and T-SOD activity in serum,whereas significantly higher(P<0.05)MDA content in the serum and liver,ROS formation,protein carbonyl content in the liver.Compared with the control and saline treatments on 42 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the relative muscle weight,the activities of mitochondrial complex ? and ?,the mitochondrial membrane potential in the breast muscle,T-AOC,the activities of GSH-Px and T-SOD,total sulfhydryl content in the muscle,whereas significantly higher(P<0.05)the contents of protein carbonyl,8-OHdG,AOPPs and MDA in the muscle,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)mitochondrial complex ? activity and membrane potential in the breast muscle,T-SOD activity and total sulfhydryl content in the muscle,GSH-Px activity in the thigh muscle,whereas significantly higher(P<0.05)the contents of protein carbonyl and 8-OHdG in the breast muscle,MDA content in the thigh muscle.Meanwhile,H2O2-treated broilers exhibited significantly higher(P<0.05)ROS formation in the muscle compared to that by the control and saline treatments,and 2.96 mmol/kg BW H2O2 had a negative effect on histomorphology and apoptotic cell number.2.The mechanism of H2O2-induced oxidative damage of liver and muscle in broilersExperiment 2:The experimental design was as same as experiment 1.We investigated the relationship between meat quality and oxidative damage caused by H2O2 in the breast muscle of broilers.Moreover,we explored the occurrence of apoptosis and autophagy,as well as the expression of NF-?B in these signaling pathways,to provide evidence of possible oxidative damage mechanisms.The results showed that compared with the control and saline treatments on 21 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the mRNA expressions of nuclear factor kappa B subunit 1(p50),B-cell CLL/lymphoma 2(Bcl-2),v-rel reticuloendotheliosis viral oncogene homolog A(RelA)and the protein expressions of nuclear factor kappa B(NF-?B)in the liver,whereas siginificantly higher(P<0.05)the mRNA expressions of caspases(3,6,8),autophagy-related gene 6(Beclin 1),microtubule-associated protein 1 light chain 3(LC3)-?/LC3-?,Bcl-2 associated X(Bax)in the liver.Compared with the control and saline treatments on 21 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the mRNA expressions of p50?Bcl-2 and RelA in the muscle,whereas significantly higher(P<0.05)the mRNA of caspases(3,6,8),Beclin 1 and Bax in the muscle,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the mRNA expressions of p50 and Bcl-2 in the breast muscle.Compared with the control and saline treatments on 42 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the expression of NF-?B in the liver,whereas significantly higher(P<0.05)the mRNA expressions of caspases(3,6,8)and protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-II/LC3-? and protein expression of total LC3-?,Bax mRNA expression in the liver,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly higher(P<0.05)the mRNA expression of caspase-6 and the protein expressions of total caspase-3 and total LC3-?,Bax mRNA expression in the liver.Compared with the control and saline treatments on 42 day post-hatch,2.96 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the mRNA expressions of p50,RelA,Bcl-2 and protein expression of total NF-?B in the muscle,whereas significantly higher(P<0.05)the mRNA expressions of caspases(3,6,8)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-II/LC3-? and the protein expression of total LC3-II,Bax mRNA expression in the muscle,and 1.48 mmol/kg BW H2O2-treated broilers exhibited significantly lower(P<0.05)the protein expression of total NF-?B in the breast muscle,p50 mRNA expression in the thigh muscle,whereas significantly higher(P<0.05)the mRNA and protein expressions of caspase-3 in the breast muscle,protein expression of total LC3-II in the muscle.3.Effects of H2O2 on oxidative damage of C2C12 cellsExperiment 3:We investigated the change of C2C12 cells exposed to H2O2 and further explored the possible path of oxidative damage.C2C12 cells attached to the substrate,the medium was added with PDTC(PDTC treatment,n=6)for 24 h or(H2O2 treatment,n=6)for 24 h.The final PDTC concentration in medium was 20 ?mol/L.The final H2O2 concentration in medium was 0.5 mmol/L.Cells cultured in DMEM were treated as control(n=6).The results showed that cells in PDTC treatments had significantly higher(P<0.05)total apoptotic rate,the mRNA expressions of caspases(3,6,9)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-?/LC3-? and the protein expression of total LC3-II,whereas significantly lower(P<0.05)the mRNA expressions of p50,Bcl-2,RelA,Cox-2 and protein expression of total NF-?B compared to that by the control treatment.Moreover,H2O2-treated cells exhibited significantly higher(P<0.05)ROS formation,total apoptotic rate,the mRNA expressions of caspases(3,6,8,9)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-?/LC3-I and the protein expression of total LC3-?,the mRNA expressions of Bax,whereas significantly lower(P<0.05)the mRNA expressions of p50,Bcl-2,RelA,Cox-1,2 and protein expression of total NF-?B compared to that by the control treatment.4.Alleviative effect and mechanism of taurine on H2O2-induced oxidative damage of muscle in broilersExperiment 4:We investigated Alleviative effect and mechanism of taurine on excessive ROS casused oxidative damage of muscle in broilers exposed to H2O2.A total of 192 28-day-old Arbor Acres male broiler chickens were randomly divided into three treatments which were arranged as non-injected treatment with basal diet(Control),2.96 mmol/kg BW H2O2-injected treatment with basal diet(H2O2 treatment),and 2.96 mmol/kg BW H2O2-injected treatment with 0.5%taurine diet(H2O2+taurine treatment).The experimental period is 14 d,and all birds in H2O2 and H2O2+taurine treatments were administered the injections on days 9 of the experiment.The results showed that BWG,FI,relative muscle weight,drip loss in breast muscle of H2O2 treatment and pH24h value in the muscle of H2O2 and H2O2+taurine treatments were significantly lower(P<0.05),and F/G of H2O2 treatment and shear force value in the muscle of H2O2 and H2O2+taurine treatments were significantly higher(P<0.05)than the control treatment.Compared with the control treatment,H2O2-treated broilers exhibited significantly lower(P<0.05)the activities of mitochondrial complex ? and ?,the mitochondrial membrane potential,T-AOC and T-SOD,GSH-Px activities,total sulfhydryl content in the breast muscle,whereas significantly higher(P<0.05)ROS formation,the contents of protein carbonyl,8-OhdG,AOPPs and MDA in the breast muscle,and broilers in H2O2+taurine treatment exhibited significantly lower(P<0.05)T-SOD activity whereas significantly higher(P<0.05)ROS formation,the contents of AOPPs and MDA in the breast muscle.Compared with the control treatment,H2O2-treated broilers exhibited significantly lower(P<0.05)the mRNA expressions of p50,Bcl-2,RelA and protein expression of total NF-?B in the breast muscle,whereas significantly higher(P<0.05)the mRNA expressions of caspases(3,6,8)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-II/LC3-? and the protein expression of total LC3-?,Bax mRNA expression in the breast muscle,and broilers in H2O2+taurine treatment exhibited significantly lower(P<0.05)the mRNA expressions of p50,Bcl-2 and protein expression of total NF-?B in the breast muscle,whereas significantly higher(P<0.05)the mRNA expressions of caspases(3,6,8)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-II/LC3-I and the protein expression of total LC3-? in the breast muscle.Moreover,BWG and FI of H2O2+taurine treatment were significantly higher(P<0.05),and F/G,shear force value in the breast muscle were significantly lower(P<0.05)than H2O2 treatment.Compared with the H2O2 treatment,broilers in H2O2+taurine treatment exhibited significantly higher(P<0.05)mitochondrial complex ? activity,T-AOC and T-SOD,GSH-Px activities in the breast muscle,whereas significantly lower(P<0.05),ROS formation,the contents of protein carbonyl and AOPPs in the breast muscle.Compared with the H2O2 treatment,broilers in H2O2+taurine treatment exhibited significantly higher(P<0.05)the mRNA expressions of p50,Bcl-2 and protein expression of total NF-?B in the breast muscle,whereas significantly lower(P<0.05)the mRNA expressions of caspases(3,6,8)and the protein expression of total caspase-3,the mRNA expression of Beclin 1,LC3-II/LC3-I and the protein expression of total LC3-? in the breast muscle.As mentioned above,the conclusions are as follows:(1)Oxidative stress induced by high concentration of H2O2 promoted the ROS formation in liver and muscle and impairment of mitochondrial function in breast muscle,and had a negative effect on histomorphology and redox status in liver and muscle,underlying a decline in growth performance and meat quality of broilers.(2)Apoptosis and autophagy processes triggered by excessive ROS increased by H2O2 that suppressed the NF-?B signaling pathway in liver and breast muscle.These observations provided additional evidence to explain a possible molecular mechanism of oxidative damage in broilers.(3)H2O2 could promot the ROS formation,and apoptosis and autophagy processes triggered by excessive ROS that suppressed the NF-?B signaling pathway in C2C12 cells,as well as the role of PDTC which is specific inhibitor of NF-?B.(4)Dietary taurine could improve the decline in growth performance and meat quality of broilers exposed to H2O2,and alleviated the oxidative damage of breast muscle induced by H2O2.This could attribute to apoptosis and autophagy processes regulated by reduced ROS induced by taurine that activated the NF-?B signaling pathway. |
PDF Full Text Request