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 influence the extravasation of plasma proteins following severe spinal cord compression trauma using immunohistochemistry to identify the plasma proteins albumin, fibrinogen and fibronectin. Fifteen rats were assigned to one of three 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° to 30 °C. The two trauma groups were either submitted to the same hypothermic procedure or kept normothermic during the corresponding time. All animals were killed 24 h following the surgical procedure. The normothermic and hypothermic trauma groups had indications of marked extravasation of albumin, fibrinogen and fibronectin at the site of the injury (T8–9). There was also pronounced 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 significant reduction of the expansion compared with that present in normothermic injured rats. Our study thus indicates that hypothermia reduces the extravasation of the plasma proteins albumin, fibrinogen and fibronectin following spinal cord compression in the rat. Such a reduction may contribute to neuroprotective effects exerted by hypothermia.