Abstract: ObjectiveTo investigate the effects of methylprednisolone （MP） on the proliferation and expression of glial fibrillary acidic protein (GFAP) in astrocytes after spinal cord injury in rats. MethodsThe spinal cords in T₈～T₁₀ in 48 male Wistar rats (10 weeks old) were exposed and the right site were semi-transected. 24 rats were administrated MP through tail vein as experiment group, and the other rats were injected equal volumes of normal saline as the control group. They were assessed with Basso, Beattie, and Bresnahan (BBB) score for ethological test every 4 d, and were sacrificed, perfused 3 d, 7 d, 14 d and 28 d after operation. The spinal cords were removed and postfixed, The expression of GFAP was observed with immunohistochemical staining and gray values determination. The GFAP positive cells were also counted. ResultsThere was no significant difference in BBB score between these groups until 21 d after operation; but the MP group rats showed significantly better functional recovery than the control group 25 d after operation. The number of positive astrocytes was less in the MP group than in the control group 3 and 7 d after operation, but there was no significant difference 14 d after operation. The GFAP expression in glial scar was significantly lower in the MP group than in the control in the first 21 d after operation, but no significant difference 28 d after operation. ConclusionThe large dose methylprednisolone administration can decrease the number of active AS, attenuate the formation of glial scars, and improve the functional recovery of the hind limbs after acute spinal cord injury.

Key words: spinal cord injury, methylprednisolone, glial fibrillary acidic protein, astrocyte, rats