Mechanism Of Neurotoxicity Induced By Deoxynivalenol In Poultry

Deoxynivalenol（DON）is a secondary metabolite produced by Fusarium,widely exists in agricultural products and feed.DON was confirmed as one of the most dangerous abiogenetic food contaminants by the world health organization.At present,there are many reports about DON toxicity research,however,the neurotoxic mechanism of DON has not been fully elucidated because of the complexity of the nervous system,and further explorations are needed.In this experiment,Fusarium graminearum was cultivated and DON was extracted and purified.After feeding a week,120 Hailan chicken（male,1 day old）were selected and randomly divided into four groups and 30 chicken of each,according to single factor experiment design.Chicken in control and treatment groups were fed the same full price diets.Chicken in low,middle and high dose of groups were oral gavaged DON solution with 0.27 mg·kg^-1,1.68 mg·kg^-1 and 12.21 mg·kg^-1 according to the feed intake,respectively.Chicken in control group were oral gavaged with the same dose of sodium chloride.The trial was conducted for 36 days,poison attack once every seven day,a total of 5 times.Before gavaged,10 chicken were randomly selected from each group,the blood was collected via wing vein for the detection of DON accumulation.At the end of the test,20 chicken from each group were slaughtered,and brain tissues were quickly collected and weighed,observe brain lesions.The contents of DON in brain tissues,calcium homeostasis,neurotransmitter levels were researched,and the ultrastructure of nerve tissue and nerve cell changes were observed.The result shows as follows:1.In the condition of temperature is 27 ℃,water content is 45 %,fusarium graminearum is grow well on the corn culture medium,and toxin-producing quantity was the highest on the 20 th day.DON was extracted and purified by the methods of crystallization and recrystallization,and the content of DON was 51.26 mg·kg^-1 in the mildew corn according to the high performance liquid charomatography（HPLC）.The purity of DON was 94.01 %.2.Compared with the control group,the chicken appeared depressed in spirit,loss of appetite,individual difference,a few light green loose stools,bloody stool occasionally,and clinical symptoms turned more serious as the increase of infected dose in treatment group on the second week.Autopsy found that the chicken brain tissue of treatment group appeared different degree of swelling,haemorrhage and the color of brain was darkengradually with the increase of infected dose.However,at the end of the trial,there was no accumulation of DON in the sera and brain tissues through HPLC detection in treatment groups.3.Pathological slice showed that,compared with control group,the chicken brain cells clearancein increased in low dose treatment group,part of the microglia surrounding nerve cells increased.In middle dose treatment group,brain cells clearance further increased,at the same time,the microglia surrounding nerve cells began to devour nerve cells.In high dose treatment group,the brain cells became sparse,appearing obviously devourment of nerve cells,which was accompanied by some nerve fiber frature.4.According to the scanning electron microscope of nervous tissue,in control group,the neuron cell membrane and nuclear membrane were integrity,chromatin distribution was uniformity.The morphology,structure and the surrounding protuberant of mitochondria and endoplasmic reticulum were all normal.Neuronal cell body of low dose treatment group appeared mild degeneration,which showed that the neuron cell membrane and nuclear membrane were integrity,chromatin distribution was uniformity.Part of the mitochondria in vacuoles degeneration,rough endoplasmic reticulum appeared mild extension and fracture,ribosomes were decreased.Neuronal cell body of middle dose treatment group appeared severe degeneration,which showed the neuron cell membrane and nuclear membrane were integrity,cell body and cytoplasm swelling,nucleus was normal.Rough endoplasmic reticulum appeared mild extension,fracture and reduced,ribosomes were decreased,the mitochondria in vacuoles was degenerated and reduced.Neuronal cell body of high dose treatment group appeared watery degeneration,even necrosis.Main shows were as follows: severe swelling in cell body and cytoplasm,part of the neuron cell membrane and nuclear membrane were damaged.The mitochondria swelling and cristae broadening gap.What was more serious was that some organelles disappear.5.Compared with the control group,the contents of [Ca²⁺]i in nerve cells and the amount of CAM in brain tissue of middle and high dose treatment group were decreased significantly（P<0.05）,the two indicators in low dose treatment group were no significant difference（P>0.05）.Compared with control group,the gene expressionquantity of CAM mRNA in treatment groups were reduced significantly（P < 0.05）,but there was no significant difference between treatment groups（P>0.05）.After determined by HPLC with fluorescene detection,it found that the chicken brain tissues excluding5-HIAA.Compared with the control group,both NE and 5-HT in brain tissues of treatmentgroups had a tendency of rise,DA showed a tendency of reduce,but all treatment groups had no significant difference（P>0.05）.Above all,DON can change brain tissue morphological structures at a certain extent,and it can damage neurons cells,reduce [Ca²⁺] i levels in nerve cells.Reduce the amount of CAM in brain tissues and its relative expression of m RNA.It suggests that DON has neurotoxin effects to the chicken.