Protective effects of angiotensin II type-1 receptor blockade with olmesartan on spinal cord ischemia-reperfusion injury: an experimental study on rats.

BACKGROUND: Spinal cord injury is a major complication of thoracoabdominal aortic operations. We aimed to investigate neuroprotective role of olmesartan administered to rats before ischemia against ischemia-reperfusion (I-R) injury.

METHODS: Twenty-four Wistar albino rats were randomly divided into three groups (n = 8 per group): group I (control group, the sham-operation group), group II (the I-R group undergoing aortic occlusion without pharmacologic treatment), and group III (olmesartan-treated group receiving 3 mg/kg/d olmesartan for 14 days before ischemia). Spinal cord ischemia was induced by infrarenal aortic clamping for 45 minutes, followed by reperfusion. Neurological status was assessed by using modified Tarlov score preoperatively and at 48 hours postoperatively. Spinal cords were harvested for histopathologic examination with hematoxylin-eosin staining and biochemical analysis for tissue malondialdehyde, superoxide dismutase, and glutathione peroxidase levels.

RESULTS: The rats in the ischemia group had severe deficits including paraplegia after surgery, and they had a worse neurological status compared with the sham group (p < 0.05). The mean Tarlov scores in the ischemia and olmesartan-treated groups at 48 hours postoperatively were 1.6 +/- 0.4 and 2.2 +/- 0.9, respectively (p < 0.05). Histopathologic analyses demonstrated typical changes of ischemic necrosis in the ischemia group; however, olmesartan attenuated tissue necrosis. Decreased spinal cord tissue malondialdehyde (p = 0.047) and increased tissue superoxide dismutase (p = 0.001) and glutathione peroxidase (p = 0.009) levels were measured in the olmesartan-treated group compared with the ischemia group.

CONCLUSION: Olmesartan may protect the spinal cord from I-R injury and reduce the incidence of associated neurological dysfunction after temporary aortic occlusion.