The Study About The Relationship Between The Expression Of Neurotrophin And Neural Plasticity Of The Rat That Infected By The RSV

Objective: To develop an animal model of recurrent respiratory syncytial virus(RSV) infected SD rats and to study the relationship between the concentration of the NT(including NGF,BDNF,NT3 and NT4) in the lung and airway neural plasticity.Methods: 60 SD rats were randomly divided into 2 groups with 30 rats in each group: control group(group A),RSV-infected group (group B,rats were infected with 5×10⁴TCID50/0.1ML RSV each week),after 8 weeks, the bronchial responsiveness of the SD rats (RSV-inoculated group and control group) was assessed. The bronchial inflammation was assessed by light microscope. SYN and NF expression in the airway of SD rats were assayed by the immunohistochemistry stanining. Hybridization in situ to evaluate whether the RSV have planted in the lung. The concen -tration of NT(including NGF,BDNF,NT3 and NT₄) in the lung of SD rats were detected by ELISA.Results: 1.general state of health: Model rats gradually emerged catarrhalic rhinitis,gasping,mussy hair and activity decreasing; 2.Body temperature:The body temperature was significantly increased compared with the control group(P<0.05) during 24 hours After RSV-inoculated; 3.Weight: There was no significant difference between the two groups; 4.Hybridization in situ to evaluate effects of butylph thalide on RSV RNA expression in rat's lung: Positive signal of RSV RNA can be found in the RSV-infected rat's lung compared with control group; 5. Bronchial responsiveness:There was no significant difference in all groups of the basal airway resistance before inhaled Histamine. The airway resistance kept rising with the escalating concentration of Histamine inhalation,the airway resistance was significantly increased compared with the control group(P<0.05); 6.The pathohistology in SD rats: The RSV infected group showed typical interstitial pneumonia under light microscope. 7.Immunohistochemistry : RSV-inoculated SD rats has a neural plasticity of the airways characterized by the increased expression of SYN and NF. The distribution density was significantly increased compared with the control group(P<0.05). Positive staining was brownish red color granule. Granule was much bulkier compared with the control group ; 8.Supernatant neurotrophins level of lung tissue homogenization: NGF and BDNF were significantly increased compared with the control group(P<0.05); The NT3 and NT4 level have no significant difference in all groups; 9.Relative analysis:The expression of NGF and BDNF are positively related to the expression of SYN (r1=0.892, r2=0.995, P<0.05 ) ,and are positively related to the expression of NF (r1=0.949,r2=0.936, P<0.05) ,and are positively related to the airway hyperresponsiveness (r1=0.929,r2=0.910, P<0.05) .Conclusion: 1 .RSV-inoculated SD rats showed neural plasticity in the airway characterized by the increased expression of NF and SYN; 2.The expression of NGF and BDNF in the lung were increa sed after recurrent RSV infection; 3.NGF and BDNF may participat e in the development of airway neural plasticity and airway hyperre sponsiveness after recurrent RSV infection.