| Lead is a common toxic heavy metal pollutant in the environment.It can threaten the health of poultry by feeding through the digestive tract.The liver is one of the key target organs attacked by lead.Many research findings revealed that oxidative stress is one of the main pathogenesis of lead-induced body damage.Allicin and quercetin are two plant extracts with strong antioxidant capacity.They can increase antioxidative effects and reduce lipid peroxidation and promote the excretion of heavy metals in the body by chelating them.In order to study the counteractive effect of against poisoning of chickens caused by lead ion,this experiment took chicken as the object,dividing 96 10-day-old chickens into 8 groups randomly.Each group is equally divided between male and female.They are the control group,lead group,allicin group,quercetin group,allicin and quercetin co-treatment group,lead and allicin co-treatment group,lead and quercetin co-treatment group,lead and allicin and quercetin co-treatment group.The chickens in the control group were given 0.5ml DDW daily by gavage.The way of lead poisoning was gavage with lead acetate solution(160 mg Pb/kg·bw/d).Garlicin was administered by mixed feeding(150 mg/kg-bw/d).Quercetin was administered by mixed feeding(600 mg/kg-bw/d).The test was treated continuously for 90 d.The protective effect and mechanism of allicin and quercetin alone or in combination on lead-induced liver toxic injury in chickens were studied in this experiment.1.The effect of Lead exposure on growth and development in chicken,and the protective effects of allicin and quercetin alone or in combination.To explore the effects of lead on chicken growth and the protective effects of allicin and quercetin alone or in combination,,blood was collected from the jugular vein of chickens on the 30th,60th,and 90th day for blood routine,blood biochemistry,and serum lead concentration detection in this test.Changes were recorded in chicken body weight within 90 days.The complete liver,kidney,brain,spleen and heart of chicken were collected,weighed and the organ index was calculated after 90 days.The lead content was determined in the liver.The results showed that:Compared with the control group,the weight of chickens in the lead group decreased,but the difference was not significant(p>0.05).Compared with the lead group,the weight of the allicin and quercetin treatment groups alone or in combination increased,but the difference was also not significant(p>0.05).Compared with the control group,the liver and kidney indices of chickens in the lead group were significantly increased(p<0.05),and serum and liver lead concentrations in the lead group were significantly increased(p<0.01).RBC and Hb in the lead group decreased significantly or extremely significantly from the 60th day(p<0.05 or p<0.01).Alb,TP and Glo decreased significantly or extremely significantly on the 90th day(p<0.05 or p<0.01).AST?LDH?UA?CR and CK in the lead group increased significantly from the 60th day(p>0.05).Compared with the lead group,allicin and quercetin alone or in combination significantly reduced liver index and kidney index(p<0.05 or p<0.05),significantly reduced lead content in serum and liver of chickens(p<0.01),and significantly or extremely significantly relieved the pathological changes of RBC,Hb,AST,LDH,Alb and CK induced by lead(p<0.05 or p<0.01).Compared with lead and allicin co-treatment group,lead and Allicin and quercetin co-treatment group had a significant decrease in serum lead concentration at the 30th day(p>0.05),UA and CR decreased significantly the 90th day(p>0.05).Compared with the lead and quercetin co-treatment group,the lead and Allicin and quercetin co-treatment group had a significant decrease in serum lead concentration at the 30th and 90th day(p>0.05),and significantly decreased in serum LDH at the 90th day(p>0.05),while the rest changes were not significant.The results show that lead can affect the growth and development of multiple organs and systems in chickens.Lead accumulates abundantly in the liver.Allicin and quercetin used alone or in combination can have a certain protective effect on this.The combined application of allicin and quercetin has a better protective effect on various organs.2.Effects of lead on antioxidant capacity of chicken liver and protective effects of allicin and quercetin alone or in combination.To explore the mechanism of lead damage to the antioxidant capacity of chicken livers and the antioxidant protective effects of allicin and quercetin alone or in combination,this test detected the MDA content and the antioxidant enzymes GSH,GSH-PX,GSH-ST,CAT,SOD,T-AOC activity in liver tissues of each group collected on the 90th day.The results showed that:On the 90th day,compared with the control group,MDA content in chicken liver tissues of the lead group was significantly increased(p<0.01),while GSH activity,GSH-PX,GSH-ST,CAT,SOD activity and T-AOC activity were significantly or significantly decreased(p<0.05 or P<0.01).Compared with the lead group,the activities of GSH,GSH-PX,GSH-ST,CAT,SOD and T-AOC in the allicin and quercetin alone or in the combined treatment group increased(p>0.05 or p<0.05),MDA content is significantly or extremely significantly decreased;Compared with allicin or quercetin alone treatment group,allicin and quercetin combined treatment group GSH,GSH-PX,GSH-ST,CAT,SOD,T-AOC increased(p<0.05 or p>0.05),MDA content decreased(p<0.05 orp>0.05).The results show that lead can destroy the oxidative defense system of chicken liver,allicin and quercetin alone or in combination which has a certain protective effect on the oxidative defense system of chicken liver.The combined application of allicin and quercetin has a better protective effect on the liver's antioxidant defense system.3.The pathological damage of lead to chicken liver and the protective effect of allicin and quercetin alone or in combination.To explore the histological changes of lead on chicken liver and the protective effect of allicin and quercetin alone or in combination,the liver tissues of chickens collected on the 90th day were observed by optical microscope and transmission electron microscope.The results showed that:Compared with the control group,the chickens in the lead group showed obvious liver damage,manifested as hepatocytes spotted necrosis,pyknosis or fragmentation of nuclei,a small amount of brown-yellow pigment deposition.More lymphocytes and heterophils were seen around the blood vessels infiltration.The ultrastructure of the lead group also showed the morphological characteristics of apoptosis,which was manifested as shrinkage of the nucleus,damage to the nuclear membrane,marginalization of chromatin,vacuolation of mitochondria,breakage and disappearance of mitochondrial ridges;Compared with the lead group,the liver tissue,nucleus,and mitochondrial damage in the lead and allicin co-treatment group,lead and quercetin co-treatment group,lead and allicin and quercetin co-treatment group were all reduced.The effect of allicin and quercetin co-treatment group was the most obvious.The results show that lead can cause damage to chicken liver tissues and cells.Allicin and quercetin alone or in combination have a certain protective effect.The combined application of allicin and quercetin has a better protective effect on lead-poisoned chicken liver tissues and cells.4.Effects of lead on mitochondrial apoptosis pathway in chicken liver and protective effects of allicin and quercetin alone or in combination.To explore the toxicity mechanism of lead to chicken liver and the protective mechanism of allicin and quercetin,the experiment used immmunohistochemistry to detect the expression of Bax protein in the mitochondrial apoptosis pathway of each group collected on the 90th day.The expression changes of Bcl-2,Bax,CytC,Caspase-3 and Caspase-9 mRNA were examined by Qrt-PCR.The results showed that:Immunohistochemical assay showed that Bax expression was increased in lead group compared with control group.The results of Qrt-PCR showed that the ratio of Bcl-2/Bax was extremely significantly decreased(p<0.01)and the transcription levels of CytC,Caspase-3 and Caspase-9 were extremely significantly increased in the lead group compared with the control group.(P<0.01);Compared with the control group,the ratio of Bcl-2/Bax was significantly increased in the quercetin group(p<0.05);Compared with the lead group,the ratio of Bcl-2/Bax was extremely significantly increased(p<0.01)and the transcription levels of CytC,Caspase-3 and Caspase-9 were extremely significantly decreased(p<0.01)in the allicin and quercetin treatment groups alone or in combination;Compared with the allicin or quercetin alone treatment group,the ratio of Bcl-2/Bax was significantly or extremely significantly increased(p<0.05 or P<0.01)and the transcription levels of CytC,Caspase-3,Caspase-9 were significantly or extremely significantly decreased(p<0.05 or p<0.01)in the allicin and quercetin combined treatment group.The results showed that lead could cause damage to animal hepatocytes through mitochondrial apoptotic pathway.Allicin and quercetin alone or in combination had certain protective effects by inhibiting mitochondrial apoptotic pathway,in which the combination of allicin and quercetin had better protective effects on hepatocytes.Conclusion:Lead can affect the growth and development of multiple organs in chickens,damage the blood system,and accumulate in the liver.Lead causes certain oxidative damage to chicken liver,destroys the ultrastructure of liver tissue and liver cells,and activates the mitochondrial apoptosis pathway of liver cells.Allicin and quercetin alone or in combination can improve liver antioxidant properties,relieve the damage of lead to liver tissue,and alleviate lead-induced liver cell damage by inhibiting mitochondrial apoptosis pathway.Moreover,the combined protective effect is more obvious. |
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