OBJECTIVETo investigate the effects and apoptosis of intrathecal injection of Methylprednisolone Sodium Succinate (MPss) for acute spinal cord injury (SCI) in New Zealand rabbits.

METHODSSeventy-two healthy New Zealand rabbits were used for the procedure and were randomly divided into two groups: SCI group and SHAM group, which was both divided into 6 subgroups, such as the vehicle group, the MPss intrathecal injection groups (1.5 mg/kg, 3.0 mg/kg, 6.0 mg/kg group), the MPss intravenous injection group and the combined injection group. TARLOV score was tested daily to evaluate the motor function. The rabbits were sacrificed 7 days after the surgery and the thoracic spinal cord sections and the sacral sections where MPss was injected were harvested for HE and TUNEL staining. Two-Factors Repeated Measures analysis of variance for TARLOV scores tested at various times and One-Way ANOVA analysis of variance for data between groups were used.

RESULTSeven days after surgery in SCI group, there was no statistical difference between the TARLOV scores of intrathecal injection of MPss 3.0 mg/kg group, 6.0 mg/kg group and MPss intravenous injection group (P > 0.05), which were all better than the vehicle group (F = 4.762, P < 0.05). Referring to the lymphocyte infiltration at the injury site in SCI group, there was statistical difference between MPss intrathecal injection 6.0 mg/kg group (1.33 ± 0.21) and the vehicle group (2.67 ± 0.21) (F = 5.793, P < 0.05) and no statistical difference between intrathecal injection of MPss 6.0 mg/kg group and MPss intravenous injection group (P > 0.05). As for the lymphocyte infiltration at the intrathecal injection site in SHAM group, there was statistical difference between MPss intrathecal injection 6.0 mg/kg group (2.50 ± 0.55) and the vehicle group (0.50 ± 0.55) (F = 17.333, P < 0.05). TUNEL staining in SCI group showed statistical difference between MPss intrathecal injection 6.0 mg/kg group (6.3 ± 1.5) and the vehicle group (20.3 ± 2.2) (F = 71.279, P < 0.05).

CONCLUSIONSIntrathecal injection of MPss can improve the functional recovery of lower limb and decrease apoptosis of neuron cells,which can provide same effects as the traditional intravenous injection of MPss in New Zealand rabbits.