Correlation Between Acute Brain Injury And Brain Metabonomics In Dichlorvos-poisoned Broilers

The aim of this study was to establish a brain injury model of acute organophosphorus poisoning in commercial broilers by oral administration of dichlorvos one time,and to explore the differences and correlations of blood glucose,biomarkers of oxidative stress,brain histopathology and brain metabolites in poisoned broilers.A total of forty-eight40--day-old healthy 817 white broilers were randomly divided into three groups: high-dose group(Hig),low-dose group(Low)and control group(Con).On the day of experiment,broilers in Hig group were fed with dichlorvos 11.3 mg/kg;Low group were fed with dichlorvos 2.48 mg/kg;Con group were fed with distilled water.After challenge,the samples of plasma and the tissue samples from cerebrum,cerebella and brainstem were collected.Blood glucose level in broiler was detected by blood glucose meter,and T-AOC,SOD,GSH and MDA content or activity in plasma were detected by kit.HE staining sections,toluidine blue staining sections,glycine silver staining sections,GFAP immunofluorescence sections and transmission electron microscope sections of cerebrum,cerebellum and brain stem of broilers were made.The pathological damage statistics of cerebrum,cerebellum and brainstem tissues and the IOD values of Nissl bodies in cerebrum,cerebellum and brainstem tissues were obtained by Case Viewer and Image-Pro Plus6.0,respectively.The whole brain of broilers were analyzed by LC-MS/MS metabonomics method.Finally,the correlation between pathological damage,blood glucose,biomarkers of oxidative stress and brain metabolites in broilers were analyzed.The results of present study as follows:(1)The broilers in the control group were normal,the broilers in the low-dose group showed depression,dyspnea,salivation,standing instability and bloody watery faeces,while those in the high-dose group showed significant dyspnea,salivation,tears,standing instability,yellowish green watery feces,and even convulsions until death.(2)Compared with the control group,the brain tissue of the two groups was slightly enlarged,the connection between each brain region was not close,the elasticity of brain tissue decreased,the arrangement of cerebellar sulcus was loose and the spacing increased.(3)Compared with the control group,the blood glucose content of broilers in the two poisoned groups were significantly higher(P <0.05 or P < 0.001),and the higher the dose of dichlorvos was,the higher the blood glucose level was.In addition,compared with the control group,the plasma oxidative stress biomarkers(SOD,MDA,GSH and T-AOC)in the two poisoned groups were significantly higher(P < 0.05 or P < 0.001).(4)The results of HE staining showed that the cerebrum,cerebellum and brainstem tissues of the control group were closely connected and the structure was normal,and the perivascular space in the brain of the two attack groups was dilated and the number was significantly increased(P <0.05 or P <0.01).In addition,the cerebellar glial cells,Purkinje cells and granulosa cells were deformed in different degrees(P <0.05 or P <0.01).At the same time,the myelin sheath and myelinated nerve fibers in the brainstem of broilers in the two poisoned groups were swollen.The results of toluidine blue staining showed that there were a large number of Nissl bodies in the cerebrum,cerebellum and brainstem neurons of the control group,while the Nissl bodies of the cerebrum neurons of the two poisoned groups were disintegrated,the cytoplasmic staining of the neurons was light,and the IOD value of the neurons decreased significantly(P <0.001).In addition,the IOD of cerebellar Purkinje cells in high-dose group increased due to the cell shrinkage(P <0.001).In low-dose group,Nissl bodies in cerebellar Purkinje cells disintegrated and neuronal IOD values decreased significantly(P <0.05).There were no significant changes in Nissl bodies in brainstem neurons in the two poisoned groups.The results of glycine silver staining showed that the nerve fibers of cerebrum,cerebellum and brainstem in the control group were clear and the myelin sheath was intact.In the two poisoned groups,the cerebellar myelin sheath swelled or even destroyed,and the brainstem nerve fibers swelled.The results of GFAP immunofluorescence showed that compared with the control group,the expression of GFAP in the cerebrum and cerebellum of broilers in the two poisoned groups decreased,while the expression of GFAP in the brainstem increased.The results of transmission electron microscope showed that compared with the control group,the mitochondria in cerebrum,cerebellum and brain trunk of the two groups were swollen,vacuolated and cristae disordered.(5)Compared with the control group,a total of 289 differential metabolites were detected in the whole brain metabolism analysis of broilers in the poisoned group under positive ion mode.Different doses of dichlorvos could significantly change the secretion of neurotransmitters(acetylcholine,glutamic acid,adenosine,etc.),energy metabolism related products(glucose-6-phosphate,dihydroxyacetone phosphate,D-ribose,acetylcarnitine,etc.),amino acid metabolism related metabolites(glutathione disulfide,leucine,N-acetyl-L-glutamic acid,γ-glutamyl cysteine,etc.)and nucleotide metabolites(uridine,Hypoxanthine,inosinic acid,etc.).(6)Correlation analysis showed that neurotransmitter secreted metabolites,energy metabolites,amino acid metabolites and nucleotide metabolites related to acute dichlorvos poisoning were significantly correlated with blood glucose,biomarkers of oxidative stress and brain injury pathology in broilers.To sum up,the brain injury model of broilers exposed to acute dichlorvos was established successfully,and the normal morphological structure of cerebrum,cerebellum and brainstem was destroyed,resulting in pathological damage in various brain areas.acute dichlorvos poisoning cauld cause hyperglycemia,oxidative stress and brain damage in broilers.Acute dichlorvos poisoning caused the disorder of neurotransmitter secretion in the brain of broilers,and the changes of energy metabolism,amino acid metabolism and nucleotide metabolism,and there was a certain correlation between brain metabolism disorder and brain injury.