Effect of Methylprednisolone on Neurological Behavior and the BDNF and NMDA Receptor Expression after Traumatic Spinal Cord Injury in Rats

Objective To study the effect of methylprednisolone on spinal cord injury rats' neural behavior and the expression of brain derived neurotrophic factor(BDNF) and N-methyl-D-aspartic acid(NMDA).Methods To establish rat model of spinal cord injury(SCI),the rats were randomly divided into sham operation group,SCI group and methylprednisolone group(n=16 in each group).Eight rats were used for the behavioral assessment and BDNF measurement,the other eight animals was for the NMDA receptor test in each group.Within 8 h spinal cord contusion,methylprednisolone(50 mg/kg) was injected for methylprednisolone group,then after that the intramuscular injection of methylprednisolone was per day reduction in 10 mg/kg,till 5 days.By using immunohistochemical staining,the distribution of BDNF in the spinal cord and positive cell localization was observed and the number of positive cells were counted.The NMDA receptor affinity(Kd) and maximum binding amount(Bmax) were measured with MK-801 radioligand method,and the rat hind limb functional was also evaluated with BBB score analysis.Results Both the number of BDNF positive cells and the BBB score in methylprednisolone group was significant higher than that of SCI group;While increased receptor affinity(Kd) and decreased Bmax for NMDA receptor in methylprednisolone group was seen less than in SCI group(P0.05).Conclusion Methylprednisolone can improve the function of rat hind limb,increase BDNF level and decreased NMDA receptor expression after spinal cord injury.