Study On The Mechanism Of Liver Damage Caused By Organophosphorus Flame Retardant EHDPHP In Chickens

Organophosphorus flame retardants(OPFRs)are associated with environmental pollution,animal health risks and have a great impact on many industries,particularly on farming.2-Ethylhexyl diphenyl phosphate(EHDPHP)is one of the newest and most widely used organophosphorus flame retardants.Previous studies have confirmed the toxic effects of EHDPHP on rodents,but the mechanisms of toxicity damage have not been studied in depth.At present,there are no studies assessing the toxicity of EHDPHP to birds.Therefore,in this experiment,chicken liver was used as the target organ for the toxic effects of EHDPHP,and the toxic effects and mechanisms of EHDPHP exposure on chickens were explored.90 pre-fed 7-day-old Hyland White Feather laying hens were treated with different concentrations of EHDPHP by gavage and sampled for analysis on days 14,28 and 42 of the trial.Examination of the effects of EHDPHP on chicken growth and development through changes in clinical performance and body weight.Examination of morphological and structural damage to chicken liver tissue caused by EHDPHP through ocular changes,histopathological and ultrastructural changes in chicken livers.The changes of AST and ALT activity in chicken liver tissue were detected by the biochemical kits to determine the effects of EHDPHP on chicken liver function.The effects of EHDPHP on liver oxidative stress indexes were analyzed by detecting the activities of SOD,GSH-Px and the content of MDA in liver tissue.The changes of iron content in chicken liver tissues were measured by inductively coupled plasma mass spectrometry,and the expression of ferroptosis-related factors(FTH-1 and TFR,GPX4,ACSL4,LOX and COX-2)were measured by real-time fluorescence quantitative PCR and Western Blot;the expression of inflammation-related indicators(NF-κB;IL-1β,IL-6 and TNF-α)were measured by real-time fluorescence quantitative PCR,Western Blot and ELISA.The results revealed that EHDPHP inhibited the growth and development of chickens.The dissection,microstructural and ultrastructural observations clearly reflected the damage caused to the liver by EHDPHP exposure.Specifically,the liver was enlarged and dark red in color;under the light microscope,the liver showed varying degrees of bruising,sinusoidal stenosis,hepatic plate disorder,vacuolar degeneration and necrosis of hepatocytes,and inflammatory cell infiltration.Transmission electron microscopy showed mitochondrial atrophy,thickening of bilayer membrane structure,reduction of mitochondrial cristae and disappearance of some mitochondrial cristae in exposed hepatocytes.The biochemical kit results showed that the levels of AST and ALT in liver tissues decreased with increasing dose of gavage(P<0.05).Meanwhile,the levels of oxidative stressin chicken liver tissue increased significantly(P<0.05)with increasing dose of gavage.EHDPHP exposure increased iron content in liver tissues(P<0.05)and caused a significant increase(P<0.05)in the m RNA and protein expression levels of ferroptosis-related factors ACSL4 and COX-2 and a significant decrease(P<0.05)in the m RNA and protein expression levels of GPX4.the relative expression of LOX and TFR m RNA was significantly upregulated.EHDPHP exposure resulted in a significant increase(P<0.05)in the relative m RNA expression levels of liver tissue inflammatory factors NF-κB,IL-1β,IL-6,and TNF-α with increasing dose of instillation;the ratio of p NF-κB/NF-κB and the expression of IL-1β,IL-6,and TNF-α were significantly higher(P<0.05).The above findings suggest that EHDPHP can cause damage to chicken liver through oxidative stress and ferroptosis,promote the synthesis and secretion of inflammatory factors,and affect growth and development in chickens.This study provides a scientific experimental basis for the diagnosis and prevention of EHDPHP exposure.