Establishment Of Animal Model For Experimental Autoimmune Encephalomyelitis And Matrix Metalloproteinase-9 Expression On EAE Rats

Objective1.To establish the animal model for experimental autoimmune encephal-myelitis (EAE) in wistar rats.2.To observe the behavior and the pathological characteristics of experimental autoimmune encephalomyelitis rat model. To detect the expression of matrix metalloproteinase-9 in EAE rats.3.To support a new consider for the treatment of multiple sclerosis.Methods:Female wistar rats were randomly divided into EAE group and complete Freund's adjuvant (CFA) group. The EAE group was induced by injecting four foot pads with guinea-pig spinal cord homogenate in complete Freund's adjuvant (GPSCH-CFA)0.4 milliliter, and coinjecting the left-back foot with bordetella pertussis vaccine (BPV) 0.2 milliliter every rat. The CFA group was injected with equal NS and CFA. Rats in each group were weighed,and clinical scores were evaluated every day. Investigate the histomorphological changes by HE staining.The MMP-9 expression in the central nervous system of EAE rats was observe by immunohistochemistry.Results:1,Changes in animal behavior:The onset of clinical syndrome on the EAE rats begined at 8-12d post inoculation. The posterior limbs weakness and paralysis appeared.While the animals crawled with forelimbs, the parts in the rear of xiphoid were on the ground. The posterior limbs dragged,with the foot plantar above. The muscular tone of tail decreased. Some rats may appeared incontinence.About 3 days later after onset the clinical syndrome reached peak. The severityindex may appeared following conditions:forelimbs hypomyotonia and limb paralysis.7 days later after onset the clinical syndrome recovered.The weight of EAE rats declined obviously.The clinical scores of EAE rats were higher than CFA rats. The highest score was 5. The CFA rats did not show the clinical syndrome of EAE. Activities and appetite were normal. The weight gradually increased.2. Histopathological chang:Under lightmicroscope,a amount of inflamma-tory cell infiltrated the brain and spinal cord of the EAE rats, in the white matter, especially around the cerebral ventricle.. Most inflammatory cells were lymphocytes, enclosing minor veins like cuffing infiltration. In KB staining demyelinating could be seen in the brain and spinal cord in crest time.. In Bodian staining the axons appaered to be normal all through the course of disease。Immunohistochemistry stainingcells,bloodshowed specific MMP-9 expression in EAE brain and spinal cord.The positive signal can be found mainly in lymphocytes and monocytes.The kytoplasm of classic positive cells was brown. The positive infiltrated cells reduced at 14 days post onset. Under electronmicroscope, the mitochondria in endothelial cells enlarged in EAE brain and spinal cord. Medullary corpuscles or ridge missing appeared. Atresia stenosis can be found. within The mitochondria and endoplasmic reticulum in Neurons enlarged. The microtubule and microfilament of myelinated nerve fiber axons were sparse. Mitochondria enlarged.Sheath twisted, separated or fractured.Conclusion1.The experimental autoimmune encephalomyelitis model had been successfully established by injected with GPSCH-CFA and coinjected with BPV in wistar rats.2.In the brain and spinal cord of EAE rats there were a amount of inflammatory cell infiltrated, enclosing minor veins like cuffing infiltration. Staining demyelinating could be seen in the white matter. The axons appaered to be normal. The pathological of EAE rats changes consistent with the pathological of multiple sclerosis.3.The expression of matrix metalloproteinase-9 in EAE rats was incresed consistently with the disease severity. It indicates that matrix metalloproteinase-9 plays an important role in the pathogenesis of EAE.