Study On The Mechanism Of Mitophagy Induced By Pesticide Chlorpyrifos In The Brains Of Common Carp(Cyprinus Carpio L.)

Chlorpyrifos is a broad-spectrum organophosphorus pesticide.Its extensive use leads to environmental pollution and harms non-target organisms.Chlorpyrifos can enter waters through drift,runoff and leaching,which can affect the health of aquatic organisms.Common carp(Cyprinus carpio L.)is one of the most widely distributed fish in the world and can be used as a model animal of environmental pollution.In this study,the brain poisoning model of chlorpyrifos on common carp was established,and 54 healthy common carp were divided into control group and treatment group.The concentration of chlorpyrifos in the treatment group was 14.5?g L^-1(the concentration of chlorpyrifos was 1/50 of LC50 of common carp).The experimental group was exposed for 45 days,and their behavior changes were observed,weight and body length data were recorded,and samples were collected.Histomorphology(microstructure and ultrastructure),biomarkers(ACh E,Na⁺-K⁺-ATPase?Ca²⁺-ATPase and Mg²⁺-ATPase),oxidative stress indexs(CAT,SOD,GSH-Px,GST,T-AOC,H₂O₂,MDA and GSH),endoplasmic reticulum stress(PERK,ATF4,enr1 and e IF2a),glucose metabolism related genes(pck2,phkb,pgm1 and dlat),and mitophagy related genes(PINK1,Park2,mfn1,mfn2,OPA1,sirt1,LC3-?,LC3-?and SQSTM1)and mi R-7a to explore the mechanism of mitophagy induced by chlorpyrifos in common carp brain tissue.The results showed that:(1)Chlorpyrifos exposure led to poor swimming balance,slow swimming and disorderly swimming route,backward swimming and side turning,black fish body,increased secretion of mucus,and inactive feeding.Growth slowed down and brain-body ratio increased.Chlorpyrifos affected the behavior and growth of common carp.(2)Microstructure results showed that chlorpyrifos exposure caused brain tissue damage of common carp.The boundaries between nerve cells were not clear,the arrangement was disordered,the number of Nissellite was reduced,and the brain tissue had red blood cells oozing.The results showed that chlorpyrifos had damaged the brain tissue of common carp.(3)The ultrastructure of common carp brain tissue showed typical characteristics of mitochondrial autophagy,including fracture of mitochondrial ridges and vacuolation of some mitochondria.Autolysosomes and autophagosomes were observed,which contained mitochondria and cytoplasmic materials.The results showed that chlorpyrifos damaged the mitochondria of common carp brain tissue,leading to the occurrence of mitophagy.(4)Chlorpyrifos inhibited the activity of ACh E and decreased the activity of ATPases(Na⁺-K⁺-ATPase,Ca²⁺-ATPase and Mg²⁺-ATPase).(5)After chlorpyrifos exposure,the contents of H₂O₂ and MDA,SOD,GPX,CAT,GST and T-AOC activities and GSH content of the antioxidant stress-related factors in the brain tissue of common carp increased,which caused the imbalance between oxidation and antioxidant,indicating that chlorpyrifos caused oxidative stress in the brain tissue of common carp.(6)Chlorpyrifos up-regulated m RNA levels of ER stress-related genes PERK,ATF4,ERN1and e IF2?.The results showed that chlorpyrifos caused endoplasmic reticulum stress in common carp brain tissue.(7)The m RNA levels of glucose metabolism-related genes pgm1 and dlat in the brain tissues of common carp were increased by excessive chlorpyrifos,while the m RNA levels of pck2 and phkb were decreased,indicating that chlorpyrifos caused glucose metabolism disorder in the brain tissues of common carp.(8)Chlorpyrifos up-regulated the m RNA levels of PINK1,Park2,LC3-?,and LC3-?,and down-regulated the m RNA levels of sirt1,mfn2,OPA1,mfn1,and SQSTM1.suggesting that chlorpyrifos caused mitochondrial autophagy in the brain tissues of common carp.PINK1/Park2mediated mitochondrial autophagy in the brain tissues of common carp.(9)Chlorpyrifos up-regulated the level of mi R-7a and down-regulated the level of VDAC1,which was the target gene of mi R-7a,and mi R-7a/VDAC1 axis was involved in chlorpyrifo-induced mitophagy in common carp brain tissue.In conclusion,miR-7a/VDAC1,oxidative stress and endoplasmic reticulum stress were involved in the mechanism of mitophagy induced by chlorpyrifos in common carp brain tissues.This study enriches and improves the toxicity mechanism of chlorpyrifos,and provides reference for risk assessment of pesticide chlorpyrifos exposure and healthy breeding of common carp.