Reduction Mechanism Of Common Mycotoxins Hazard In Fish/Shrimp By Liver Microsome Enzyme Regulation

As the agricultural development is highly valued in our country,the standardized aquaculture has opened up huge prospects for the agricultural economy.But,there are many problems can not be solved timely in the process of aquaculture,due to the lack of professional knowledge which seriously restricts the development of aquaculture.Recently,low-priced plant protein gradually replaces animal protein source in aquatic feed production,which reducing the production cost but increase the risk of mycotoxin contamination at the same time.Moreover,the plant source aquatic feed is easy to mildew during the process of production-transportation and storage.As the mildewed aquatic feed produce mycotoxins,it can cause the growth rate decreased and body damage in fish and shrimp.What's worse,when the contaminated fish and shrimp processed into aquatic food,the residual mycotoxins in food will cause serious food safety problems and harmful to humans health.The literatures showed that plant secondary metabolites,such as rutin,quercetin and tea polyphenols have induced effect on metabolic enzyme activity and those can be induced.Therefore,metabolic capacity of aquatic animals can be increased to metabolize mycotoxin and decrease toxin residues through regulating metabolic enzyme activity by effective inducers,which has important significance to reduce the harm to the aquatic animal.Study the growth rate,metabolism and pathological changes of Litopenaeus vannamei shrimp and Tilapia after exposed to T-2?T-2 toxin?,AFB₁?Aflatoxin B₁?,OTA?Ochracin A?and DON?Deoxynivalenol?toxins through contaminated feed.Then,adding rutin,quercetin and tea polyphenols into feed to study the antagonistic effects to those mycotoxins.Using microcapsule method to prepare three kinds of feeds contain mycotoxins,inducers,mixed mycotoxins and inducers,repectively.Litopenaeus vannamei shrimp and Tilapia were exposed to T-2,AFB₁,OTA and DON for 20 days by microcapsule feeding.Mycotoxin residues in liver and muscle of shrimp and fish were detected by liquid chromatography tandem mass spectrometry?LC-MS/MS?.Damages of mycotoxins in shrimp and fish were evaluated by histology observation and metabolic enzyme activity.Quercetin,rutin and tea polyphenols were addicted to the decrease the mycotoxin injury in shrimp and fish.Conclusions:?1?The weight gain rate and survival rate significantly decreased in shrimp and fish after four kinds of mycotoxins exposure.Hepatopancreas cells of shrimp showed different degrees of injury,especially the decrease in embryo cells,autophagy was observed at high dose exposure.Light purple in hepatocytes cytoplasm after DON exposure that demonstrated significantly liver glycogen consumption in Tilapia.Muscle fibers of shrimp and Tilapia gapped gradually with the increase of exposure dose,and it can be obviously observed in single fibers at 20 d,which suggests that mycotoxin exposure on muscle damage could not be repaired.The residues of mycotoxin in liver and muscle were positively correlated with exposure dose.Four mycotoxins residue accumulation order in shrimp:AFB₁>T-2>OTA>DON.In Tilapia:T-2>AFB₁>OTA.Phase I and phase II metabolic enzymes activity showed an inverted U-shaped change manner,which is in accordant with the poison stimulation effect model.?2?Decreased weight gain rate and survival rate of shrimp and fish were observed after quercetin,rutin and tea polyphenols addition.Compared with quercetin and tea polyphenols,rutin caused significantly increase of liver weight ratio in shrimp and abnormal lumen,slight vacuoles and cell lysis.Increased muscle fiber gap was observed in three inducer groups.Content of cytochrome b₅ was significantly increased in shrimp and fish liver microsomal,which indicated that those inducers have a significant effects on active reaction mediated by b₅.SULT enzyme activity showed a significant increase in three inducer groups.Compared with quercetin and rutin,tea polyphenols induced more kinds of metabolic enzymes and caused less pathological damage in aquatic animals.?3?Increased weight gain rate was observed after DON and inducer combined exposure in shrimp,but was still the lowest in four mycotoxin groups.Compared with other mycotoxin groups,liver weight ratio was relatively high and weight gain rate was decreased in fish after AFB₁ exposure,which showed strong accumulation of AFB₁ in fish.Mycotoxins residues in aquatic animals were lower than exposed alone after combined with those inducers,which showed that the inducer has a certain effect on the elimination of toxin residues.Tea polyphenols have a better reduction on T-2 and AFB₁,while rutin on OTA and DON.Mycotoxins in aquatic animals muscle showed strong accumulation than liver.Completed cell structure,increased content of b₅ and high induction of metabolic enzymes activity were observed in tea polyphenol groups,which indicate that tea polyphenols obviously reduce mycotoxins damages in aquatic animals.Therefore,tea polyphenols can be used as feed addition to reduce damage in aquatic animals after mycotoxin pollution.