Neuroprotective effect of N-acetylcysteine and hypothermia on the spinal cord ischemia-reperfusion injury

The purpose of this study was to investigate the effect of N-acetylcysteine (NAC) on spinal cord ischemia-reperfusion (I-R) in rabbits. Thirty rabbits were divided into five equal groups, group I (sham-operated, no I-R), group II (control, only I-R), group III (I-R + NAC), group IV (I-R + hypothermia), group V (I-R + NAC + hypothermia). Spinal cord ischemia was induced by clamping the aorta both below the left renal artery and above the aortic bifurcation. Forty-eight hours postoperatively, the motor function of the lower limbs was evaluated in each animal according to Tarlov Score. Spinal cord samples were taken to evaluate the histopathological changes. The sham-operated rabbits (group I) showed no neurologic deficit (Score = 4). Paraplegia (Score = 0) developed in all rabbits in the control group (group II). Administration of 50 mg/kg of NAC (group III) resulted in significant reduction of motor dysfunction (Score = 3.1 +/- 1.3, p = 0.002). Application of hypothermia alone (group IV) showed significant recovery of motor functions (Score = 3.0 +/- 1.1, p = 0.002), and combination of hypothermia and 50 mg/kg of NAC (group V) showed complete recovery of lower limb motor function (Score = 4, p = 0.001). Histologic examination of the spinal cord in rabbits with paraplegia revealed several injured neurons. The cords of animals with no motor function deficits showed only minimal cellular infiltrates in the gray matter, and there was good preservation of nerve cells. NAC showed protective effects of the spinal cord. Moderate hypothermia alone also showed protective effects. Combined use of NAC and hypothermia resulted in highly significant recovery of spinal cord function. (C) 2003 The International Society for Cardiovascular Surgery. Published by Elsevier Ltd. All rights reserved.