Study On The Mechanism Of Apoptosis Of Caused By Heavy Mental Cadmium Exposure In Common Carp Kidneys

Cadmium（Cd）is a toxic heavy metal that can accumulate in animals and humans through the food chain.Human activities will increase the concentration of Cd in the water,which will affect the health of aquatic organisms.Common carp（Cyprinus carpio L.）is a widely cultivated freshwater fish.The kidney is the excretory organ and a target organ for Cd.Studies have found that apoptosis is a mechanism of body poisoning.However,it is not clear whether Cd poisoning causes apoptosis in common carp kidneys.Therefore,this experiment established a common carp model of Cd poisoning,and 54 healthy common carps were randomly divided into the control group and the Cd group.The concentration of the Cd group was 0.26 mg/L(1/25 of the 96-hour LC₅₀).On the 45th day of the experiment,common carp blood and kidney tissues were collected.The automatic biochemical analyzer was used to detect blood test indexes of renal function（CREA,UREA and UA）,the digital slice scanner and transmission electron microscope were used to observe the microstructure and ultrastructure of kidney,respectively.The ICP-MS method was used to detect trace elements（Fe,Mn,Zn,Se,Mo,and Cd）,the assay kits were used to detect oxidative stress related indicators（SOD,GPx,CAT,H₂O₂,and MDA）and ATPase(Na⁺K⁺-ATPase,Ca²⁺Mg²⁺-ATPase,Ca²⁺-ATPase,and Mg²⁺-ATPase),The TUNEL method was used to detect apoptosis,the q RT-PCR method was used to detect mi R-143,mitochondrial apoptosis pathway related genes（P53,Bax,Apaf-1,AIF,Caspase-9,and Caspase-3）and death receptor apoptosis pathway related genes（Fas,Fas L,FADD,TNF-α,TNFR1,TRADD,and Caspase-8）and energy metabolism related genes（PK,LDHA,LDHB,HK1,HK2,Aldh1a2,Idh1,and CS）,the Western Blot method was used to detect mitochondrial apoptosis pathway related genes（Bax,Bcl-2,Cyt-C,Apaf-1,Caspase-9,and Caspase-3）.To study the mechanism of apoptosis caused by Cd exposure in common carp kidneys.The results showed that:（1）Cd exposure caused the shrinking of glomeruli,renal capsules space expanded,and there were red blood cells infiltration in the glomeruli and renal interstitium,Cd exposure caused common carp kidney damage;（2）Cd exposure increased the concentration of CREA,UREA,and UA in the blood,Cd exposure led to decline in renal function;（3）After Cd treatment,the content of Fe,Mn,Zn,Se,and Mo decreased,Cd exposure decreased trace element content;（4）Cd exposure decreased the activities of SOD,GPx,and CAT,increased the contents of H₂O₂ and MDA,Cd exposure caused oxidative stress;（5）Cd exposure caused nuclear chromatin agglutination,cytoplasmic contraction,and mitochondrial swelling in kidney tissues,and increased the apoptotic rate of cells,Cd exposure caused apoptosis;（6）Cd exposure increased m RNA expression of P53,Bax,Apaf-1,AIF,Caspase-9,and Caspase-3,and protein expression of Bax,Cyt-C,Apaf-1,Caspase-9,and Caspase-3;reduced m RNA and protein expression of Bcl-2,the mitochondrial apoptosis pathway was involved in apoptosis caused by Cd exposure;（7）Cd exposure increased m RNA expression of Fas,Fas L,FADD,TNF-α,TNFR1,TRADD,and Caspase-8,the death receptor apoptosis pathway was involved in apoptosis caused by Cd exposure;（8）In the Cd poisoning model,the expression of mi R-143 increased,the expression of Bcl-2decreases,Bcl-2 is the target gene of mi R-143,mi R-143/Bcl-2 axis mediated apoptosis caused by Cd exposure;（9）Cd exposure inhibited the activities of Na⁺K⁺-ATPase,Ca²⁺Mg²⁺-ATPase,Ca²⁺-ATPase,and Mg²⁺-ATPase,Cd exposure affected energy metabolism;（10）Cd exposure reduced the m RNA expression of energy metabolism-related genes（PK,LDHA,LDHB,HK1,HK2,Aldh1a2,Idh1,and CS）,Cd exposure led to energy metabolism disorder.