The Effect of Methylprednisolone on the Therapeutic Window of Systemic Hypothermia for the Treatment of Experimental Mild Traumatic Spinal Cord Injury in Rat

Many studies have shown the neuroprotective effect of systemic hypothermia in the treatment of spinal cord injury. But the effect of delay hypothermia is not known.The goal of this study was to evaluate the effects of Methylprednisolone on the therapeutic window of hypothermia treatment following experimental Spinal Cord Injury (SCI) by measuring the accumulation of Polymorphonuclear leukocytes(PMN) at the traumatic site. In an experimental study, twenty-four Wistar albino rats (260–300 g) were divided in to six groups of four each: A(only laminectomy), B(Trauma laminectomy + cord injury), C(methylprednisolone laminectomy + cord injury + methylprednisolone), D(early hypothermia laminectomy + cord injury + early hypothermia), E(late hypothermia laminectomy + cord injury + late hypothermia), and F(late hypothermia + Methylprednisolone laminectomy + cord injury + late hypothermia +MP). Traumatic spinal cord injury (SCI) was induced by using Weight drop method(30 g.cm) on the anesthetized animals at T9 level. Tissue samples from the spinal cord were harvested 7 hours after laminectomy. PMNs counting was performed by light microscope and the data were analyzed using One-way ANOVA. Early hypothermia and methylprednisolone inhibited PMN accumulation, but late hypothermia (induced 3 hours after trauma) did not show significant effect on PMN count. Delay hypothermia and Methylprednisolone decreased the number of PMN, but it seemes that this effect was related to methylprednisolone. Adding methylprednisolone to delay hypothermia, did have significant beneficial effect, but it was not more than "methylprednisolone alone" group. Methylprednisolone can not extend the Therapeutic window of systemic moderate hypothermia for the treatment of experimental mild traumatic spinal cord injury in rat.