OBJECTIVETo study different effects of Herba Lycopodii (HL) Alcohol Extracted Granule combined methylprednisolone on behavioral changes, brain derived neurotrophic factor (BDNF) expression levels, and N-methyl-D-aspartate (NMDA) receptor levels in rats with spinal cord injury (SCI).

METHODSMale adult SD rats were randomly divided into five groups, i.e., the sham-operation group, the model group, the HL treatment group, the methylprednisolone treatment group, the HL + methylprednisolone treatment group. Rats in the HL treatment group were intragastrically administered with HL at the daily dose of 50 mg/kg for 5 successive days. Rats in the methylprednisolone treatment group were intramuscularly injected with 50 mg/kg methylprednisolone within 8 h after spinal cord contusion, and then the dose of methylprednisolone was reduced for 10 mg/kg for 5 successive days. Rats in the HL + methylprednisolone treatment group received the two methods used for the aforesaid two groups. Basso Beattie and Bresnahan (BBB) score (for hindlimb motor functions) were assessed at day 0, 3, 7, and 28 after operation. At day 13 after SCI, injured spinal T8-10 was taken from 8 rats of each group and stored in liquid nitrogen. The N-methyl-D-aspartate (NMDA) receptor affinity (Kd) and the maximal binding capacity (Bmax) were determined using [3H]MK-801 radioactive ligand assay. Rats' injured spinal cords were taken for immunohistochemical assay at day 28 after SCI. Expression levels of BDNF in the ventral and dorsal horn of the spinal cord were observed.

RESULTSCompared with the sham-operation group, the number of BDNF positive neurons in the ventral and dorsal horn of the spinal cord increased in the model group, Bmax increased (470 ± 34), Kd decreased, and BBB scores decreased at day 3 -28 (all P <0. 05). Compared with the SCI model group, the number of BDNF positive neurons and Kd increased, BBB scores at day 3 -28 increased (P <0. 05) in each medicated group. Bmax was (660 ± 15) in the methylprednisolone treatment group, (646 ± 25) in the HL treatment group, and (510 ± 21) in the HL +methylprednisolone treatment group (P <0. 05). Compared with the methylprednisolone treatment group, the number of BDNF positive neurons and Kd increased, BBB scores at day 7 -28 increased, and Bmax decreased in the HL treatment group and the HL + methylprednisolone treatment group (all P <0. 05). Compard with the HL treatment group, the number of BDNF positive neurons and Kd increased, and Bmax decreased (all P < 0.05).

CONCLUSIONSHL could effectively improve motor functions of handlimbs, increase expression levels of BDNF in the spinal cord, and lessen secondary injury by affecting spinal levels of NMDA receptors. It showed certain therapeutic and protective roles in treating SCI. Its effect was better than that of methylprednisolone with synergism.