Systemic hypothermia following compression injury of rat spinal cord: reduction of plasma protein extravasation demonstrated by immunohistochemistry

Systemic hypothermia has neuroprotective effects in experimental models of central nervous system ischemia caused by vascular occlusions. The present study addresses the question as to whether systemic hypothermia can influen ce the extravasation of plasma proteins following severe spinal cord compre ssion trauma using immunohistochemistry to identify the plasma proteins alb umin, fibrinogen and fibronectin. Fifteen rats were assigned to one of thre e groups and received either thoracic (T) laminectomy or severe spinal cord compression trauma of the T8-9 segment. One group comprised laminectomized animals without compression trauma submitted to a hypothermic procedure in which the core temperature was reduced from 38 degrees to 30 degrees C. Th e two trauma groups were either submitted to the same hypothermic procedure or kept normothermic during the corresponding time. All animals were kille d 24 h following the surgical procedure. The normothermic and hypothermic t rauma groups had indications of marked extravasation of albumin, fibrinogen and fibronectin at the site of the injury (T8-9). There was also pronounce d extravasation in the cranial and caudal peri-injury zones (T7 and T10) of normothermic injured rats but, with few exceptions, not in the hypothermic ones with the same degree of compression. By measuring the cross-sectional area of the peri-injury zones we found in the hypothermic trauma group a s ignificant reduction of the expansion compared with that present in normoth ermic injured rats. Our study thus indicates that hypothermia reduces the e xtravasation of the plasma proteins albumin, fibrinogen and fibronectin fol lowing spinal cord compression in the rat. Such a reduction may contribute to neuroprotective effects exerted by hypothermia.