Effect of osthole on p38 MAPK signaling related pathway of rat model with inflammatory radicular pain induce by nucleus pulposus in the spinal horn / 中国药理学通报

ABSTRACT

Aim To observe the effect of epidurally application of osthole on the model of nucleus pulposusinduced inflammatory radicular pain and the expression of p38 MAPK signaling related pathway in the spinal dorsal horn of rats.Methods The model of radicular pain was generated by putting nucleus pulposus to the L5 dorsal root ganglion (DRG).50％ MWT was measured using Von Frey filaments to calculate mechanical pain threshold before and after operation.50 μL of 20 g · L-1 osthole was administered epidurally in group Ost and 50 μL of 100 mL · L-1 DMSO in group DMSO at postoperative day (POD).The expression of phosphorylated p38 (p-p38),IL-18 and IL-18R in the lumbar spinal dorsal horn was detected by Western blot.IL-18 mRNA was assessed by real-time PCR.Results The mechanical pain threshold significantly decreased after operation (P ＜ 0.05),while the expression of protein p-p38 MAPK,IL-18,IL-18R and IL-18 mRNA was significantly different.Compared with DMSO group,50％ MWT was significantly increased and accompanied with the decrease of protein p-p38,IL-18,IL-lgR and IL-18 mRNA in Ost group after drug administration (P ＜ 0.05).The correlation analysis between protein concentration of p38 MAPK and IL-18 mRNA showed that the Spearman correlation coefficient was 0.9 (P ＜ 0.05).Conclusion p-p38 and IL-18 of spinal dorsal horn participate in the rat model with inflammatory radicular pain induced by nucleus pulposus,and IL-18R plays a role in maintenance of the pain.Osthole administered epidurally in the early stage of pain could alleviate the pain for a long time,which may be related with inhibiting p38 MAPK signaling related pathways.