Observation and establishment of an animal model of tractive spinal cord injury in rats

Objective: To establish an animal model of tractive spinal cord injury in rats in order to investigate its pathophysiological changes and clinical significance.Methods: T12-L3 spines were tracted longitudinally with a special spinal retractor that was put on the proccessus transverses of T12-L3 vertebrae of the rat after exposing T13-L2 spinal cord via dual laminectomy.At the same tine, the spinal cord function was monitored by cortical somatosensory evoked potential （CSEP）. Rats were randomly divided into four groups according to the amplitude of CSEP P1-N1 wave, the amount of the decreasing P1-N1 wave was 30% （the 30% group）, 50% （the 50% group） and 70% （the 70% group）, respectively. After traction, the changes of the neural behavioral function in rats were observed and the morphological structure of the spinal cord was analyzed quantitaltively with image analysis system of computer.Results: With traction of spine, compared with the control group, the 30% group had no marked difference in combined behavioral score （CBS）, neuron count, section area of neuron and Nissl body density, but the 50% and 70% groups had marked differece (P<（0.01）). Light microscope showed that the neuron volume was slightly small and the Nissl body was reduced lightly in the 30% group; the neuron space was enlarged and the neuron was degenerative, reductive, and dissolved, and the spinal cord structure was destroyed in the 50% and 70% groups.Conclusions: The animal model of tractive spial cord injury in rats is a reproducible, graded and clinic mimic. The model in this article provides a valuable assistance in further understanding etiopathology and screening effective miasures of therapy and prophylaxis of the injury.