A Study On The Changes Of Axons, Myelin Sheath, APP And Nogo After Multiple Cerebral Concussion In Rats

Objective:To observe the changes of neuronal axons , myelin, APP and Nogo following multiple cerebral concussion (MCC) in rats , our target is to study the path—machanism of second-impact syndrome (SIS). Methods: Animal modle of MCC was induced by a metallic pendulum- striker concussive device in rats. Animals subject -ted MCC were randomized into six injured groups (the group of 1d, 2d, 4d, 8,16d and 24d post- concussive injury, n=8).8 intact rats served as one control. Axons and myelin sheath were conducted respect- tively histochemistry staining using Biels -chowsky and weil's methods. APP and Nogo were marked used anti-APP and anti-Nogo polyclonal antibody by the immunohistochemistry (streptavidin - peroxi -dase , S-P) method. The intensity of the positive APP and Nogo-immuno -reactive axons in brain stem were qualitatively analyzed by light microscope; The axons diameter and the degeneration of myelin sheath in brain stem, the expression of APP and Nogo in neuron of brain stem, CA3 and FrP were quantitative evaluation by computer image analyze system. The data were analyzed by rank sum test, one-way anova and q test. Results:1.Some axons pathological changes in brain stem were observed .that is axonal swelling, misalignment, disconnection and giving rise to axonal retraction bulbs. The axons diameter in brain stem of all MCC groups increased comparing with the control group , and there were significant different from control (P<0. 05) at 2d and 4d groups . 2. Myelin sheath in brain stem after injuryed show the signs of various severity of myelin sheath swelling, degenerating and tortousity. All MCC...