Effect of methylprednisolone pretreatment of ischemia-reperfusion injury of spinal cord on expression of caspase-3 in rats

Objective To investigate the effect of methylprednisolone (MP) pretreatment of ischemia-reperfusion injury of spinal cord (SCII) on expression of caspase-3 in rats. Methods One hundred and twenty healthy, purebred, adult male SD rats were randomly divided into 3 equal groups (n = 40).Croup A was a normal one in which only the abdominal aorta was exposed without establishing an injury model. Croup B was an SCII model in which the abdominal aorta was first obstructed for 30 minutes and then relaxed and next reperfused. After reperfusion for 3 hours, the rats were killed to harvest samples of lumbar spinal cord. Group C was an MP pretreatment one in which tail intravenous injection of MP (30mg/kg) was conducted 30 minutes before establishment of an SCII model. Pathological changes of the injured spinal cord were observed by HE staining, and expressions of caspase-3 in the spinal cord tissue were observed by immunohistochemical staining. Results In group A, the outlines of neuronal cells were clear with polarity and a round nucleus. Ramified Nissl bodies were evenly arranged around the nucleus. Cytoplasm was stained uniformly dark. Organizational structure was integrated and clear without neutrophile granulocyte infiltration,hemorrhage or edema. In group B, neuronal cells were swelling and decreased in quantity, with blunt polarity and mild atrophy of nucleolus. Cranuloses of Nissl bodies were observed with pale staining. There was neutrophile granulocyte infiltration. In group C, mild edema was observed in part of neuronal cells, nucleoli were still clear and there was no neutrophile granulocyte infiltration. Caspase-3 was highly expressed in the spinal cord tissue in group B, with significant differences compared with group A ( P < 0. 05). Expression of caspase-3 in the spinal cord was slightly increased in group C, but the difference was significant compared with group B (P < 0. 05) . Conclusion Since MP pretreatment can reduce expression of caspase-3 in SCII rats, preventive use of MP may alleviate SCII and help protect neural function of the spinal cord. Key words: Spinal cord;  Reperfusion injury;  Methylprednisolone;  Rats;  Caspase-3