Beneficial Effects of Intrathecal Injection of Methylprednisolone Against Spinal Cord Injury in Rats

Abstract

Background: High dose intravenous (i.t.) injection of methylprednisolone (MPSS) for spinal cord injury (SCI) is clinically controversial. Objectives: This study aimed to investigate whether i.t. MPSS would have a beneficial effect on SCI and whether or not it is a safe operation for SCI patients. Methods: An animal experiment was conducted to explore the safety and feasibility of i.t. Administration of MPSS. Male Sprague-Dawley rats were randomly divided into four groups: (1) sham group, i.t. injection of normal saline (NS) (n = 25); (2) control group, SCI surgery (created using the Infinite Horizon IH-400 impactor) with i.t. injection of NS (n = 25); (3) i.t. MPSS1 group, SCI with i.t. injection of MPSS by a pulse therapy (n = 25); (4) i.t. MPSS2 group, SCI with i.t. injection of MPSS intermittently (n = 25). Malondialdehyde (MDA), superoxide dismutase (SOD), and inflammatory cytokines in serum were measured at 6h, 24h, 48h, 7d, and 14d after surgery with commercial assay kits. Glial fibrillary acidic protein (GFAP) level was observed at 14 days after surgery by immunohistochemistry. Motor evoked potentials (MEP) and somatosensory evoked potential (SEP) were monitored and recorded separately before surgery and 1, 7, and 14 days after surgery. Also, locomotor function was evaluated using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Results: The results showed that the levels of MDA and SOD, and three inflammatory cytokines, including IL-1b, IL-6, and TNF-α were reduced in i.t. MPSS groups than that of the control group (all P < 0.05). The expression of GFAP was inhibited after i.t. MPSS treatment. The amplitude was reduced, and the latency period of SEP and MEP recovery was prolonged (all P < 0.05) after MPSS administration. In addition, the recovery of limb function (BBB score) was significantly ameliorated (P < 0.05) in SCI rats treated with MPSS compared with the control group. Conclusions: Our results demonstrated that i.t. MPSS was a potential strategy for reducing the secondary damage after SCI, especially the MPSS pulse therapy.