A rat model of spinal cord ischemic injury

Abstract

There is a need of ischemic model of spinal cord injury to identify the therapeutic window for intervention of ischemic injury in humans. Calcium for long has been known to be a key source of neuronal damage during ischemic injury. The purpose of this study is to develop an in vivo model of spinal cord ischemia in rats and to confirm the functionality of the model by studying the expression pattern of inositol 1,4,5-triphosphate receptor isoform 1 (IP3R1) and ryanodine receptor isoform 2 (RyR2). Ischemic injury was induced by clamping the aorta below the azygous vein using thoracotomy approach for 27 minutes. Behavioral and histopathologic studies were done at 0, 2, 4, 8, and 48 hours after injury. Eighteen rats suffered from complete paralysis and two showed perceptible movement of the joints of their hind limbs. There was no paralysis in five animals (Sham Group). Histopathology with hemotoxylin and eosin stain at 8 and 48 hours demonstrated neuronal cell loss and diffused neuronal necrosis. Glial fibrillary acidic protein staining showed severe reactive gliosis. Apoptosis was also visualized at 48 hours of ischemia. Expression of IP3R1 and RyR2 was upregulated after ischemic injury and expression of RyR2 increased until 8 hours after injury, while the maximum expression of IP3R1 was observed 4 hours after injury. This preliminary study confirmed that this model of ischemic spinal cord injury causes paralysis and significant changes in neurology and histopathology with time. Increased expression of IP3R1 and RyR2 confirms the functionality of the model by showing increased intracellular calcium levels. Keywords: Calcium, Ischemic injury, Spinal cord, Rat model DOI:10.5055/jndr.2013.0008