Systemic hypothermia following spinal cord compression injury in the rat: an immunohistochemical study on MAP 2 with special reference to dendrite changes

Systemic hypothermia has been shown to exert neuroprotective effects in exp erimental ischemic CNS models caused by vascular occlusions. The present st udy addresses the question as to whether systemic hypothermia has similar n europrotective qualities following severe spinal cord compression trauma us ing microtubule-associated protein 2 (MAP2) immunohistochemistry combined w ith the avidin-biotin-peroxidase complex method as marker to identify neuro nal and dendritic lesions. Fifteen rats were randomized into three equally sized groups. One group sustained thoracic laminectomy. the others severe s pinal cord compression trauma of the T8-9 segment. The control roup contain ed laminectomized animals submitted to a hypothermic procedure in which the esophageal temperature was reduced from 38 degrees C to 30 degrees C. The two trauma groups were either submitted to the same hypothermic procedure o r kept normothermic during the corresponding time. All animals were sacrifi ced 24 h following the surgical procedure. The MAP2 immunostaining in the n ormothermic trauma group indicated marked reductions in MAP2 antigen in the cranial and caudal peri-injury zones (T7 and T10, respectively). This redu ction was much less pronounced in the hypothermic trauma group. In fact, th e MAP2 antigen was present in almost equally sized areas in both the hypoth ermic groups independent of previous laminectomy alone or the addition of t rauma. Our study thus indicates that hypothermia has a neuroprotective effe ct on dendrites of rat spinal cords subjected to compression trauma.