Establishment and stability of the animal models of spinal cord venom hypertension

Objective To establish a stable model of spinal cord venous hypertension in rabbits. Methods Thirty-six rabbits were recruited and randomly divided into three groups:short-term, mid-half, long-term. In each group,8 rabbits were subjected to arteriovenous fistula establishment, and the rest 4 to sham operation, respectively. Side to side anastomosis between lett renal artery and vein was performed to establish the arteriovenous fistulas. We ligated the distal end of the inferior vena cave as well as its proxi-mal end, in order to make the arterial blood stream drains anomalously to lumbar veins and internal verte-bral veins, resulting in spinal cord congestion and spinal cord venous hypertension. The grade of hind limb function was assayed with Jacobs method,and the kinetic and sensory function of spinal reflex were scored with Reuter method. The changes of behavior in rabbits were observed continuously. MRI and DSA from femoral artery were performed among rabbit models in each group on time to check the arteriovenous fistu- las,and then the animals were sacrificed after perfusion and the spinal cord was removed for histopatholog-ic examination. Results Of the 24 animals in model group,22 survived and 2 died. The survival rate was 91.67%. The kinetic and sensory function of hind limb was decreased after operation as compared with control groups. MRI showed the spinal cord edema at the corresponding stage, but which used for judge-ment of early pathologic change of spinal cord venous hypertension was not specific. Under light microsco-py, the pathological features of spinal cord hypertension were marked capillary expansion and congestion within the spinal cord, perivascular lymphocyte infiltration, gliosis, hyalinized vessels in spinal cord, neu-runs cellular degeneration. Transmission electron microscopy revealed myelin sheath layers loose, the in- creased number of mitochondria within thin-myelinated fibers,and pycnosis neurons. Conclusion We es-tablished an animal model of spinal cord injury caused by spinal cord venous hypertension,which simulated spinal cord vascular malformation of human. The animal model with great reliability and stability could be used for further studies on spinal vascular diseases caused by venous hypertension,and as a perfect model to study the mechanism of spinal cord venous hypertension. Key words: Rabbits;  Spinal cord ;  Venous hypertension;  Model,animal