8-O-乙酰山栀子苷甲酸通过抑制脊髓背角JNK的磷酸化水平改善大鼠炎性痛的研究

目的:探究8-O-乙酰山栀子苷甲酸(8-O-acetyl-SM,8-Oa S)对于慢性炎性痛模型大鼠痛行为及脊髓背角星形胶质细胞内c-Jun氨基酸末端激酶(c-Jun N-terminal kinase,JNK)磷酸化水平的影响。方法:运用大鼠足底注射完全弗式佐剂(complete Freund’s adjuvant,CFA)的方法建立慢性炎性痛模型;通过腹膜腔注射8-Oa S进行干预;采用von Frey丝测定大鼠足底50%机械性缩足反射阈值;应用免疫荧光组织化学染色法观察大鼠腰膨大节段脊髓背角胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)及磷酸化的JNK(phosphorylatedc-Jun N-terminal kinase,p JNK)表达;应用Western Blot方法对大鼠脊髓背角内GFAP、JNK以及p-JNK的表达水平进行定量分析。结果:(1)行为学结果显示:与对照组相比,CFA模型大鼠机械性痛阈明显降低(P0.01),腹膜腔注射8-Oa S可有效提高CFA诱导的机械性痛阈值(P0.05);(2)免疫荧光染色结果显示:CFA模型脊髓背角内GFAP的表达量明显高于正常组,且p JNK基本表达于星形胶质细胞内;(3)Western Blot结果显示:与对照组相比,CFA造模后7 d脊髓背角内GFAP和p JNK表达明显上调,腹膜腔给予8-Oa S可以显著下调CFA诱导的脊髓背角内GFAP和p JNK的水平(P0.01)。结论:腹膜腔内给予8-Oa S可有效提高炎性痛大鼠的机械性痛阈,其机制是通过下调脊髓背角星形胶质细胞内JNK信号通路的磷酸化水平进而抑制星形胶质细胞的激活。

8-O-acetyl-SM attenuates chronic inflammatory pain via inhibition of JNK phosphorylation in spinal dorsal horn of rats

Objective:To explore effects of 8-O-acetyl-SM (8-OaS) on complete Freund's adjuvant (CFA)-induced nociceptive behavior and expressions of phosphorylated c-Jun N-terminal kinase (pJNK) of astrocytes in the spinal dorsal horn of rats.Methods:Chronic inflammatory pain was established by intraplanter injection of complete Freund's adjuvant (CFA).8-OaS was injected intraperitoneally (i.p.).yon Frey filaments were used to investigate the 50％ mechanical allodynia of the planta of rats.Immunofluorescent histochemistry was applied to observe the expression of glial fibrillary acidic protein (GFAP) and pJNK.Western Blot was performed to qualitatively analyze the expression levels of GFAP,JNK and pJNK.Results:(1) Behavioral results showed that the mechanical withdrawl threshold was obviously and significantly decreased in CFA group compared to control group (P ＜ 0.01),and i.p.treatment of 8-OaS can greatly attenuate CFA-induced mechanical allodynia (P ＜ 0.05).(2) Immunofluorescent histochemical staining showed that the expression of GFAP was significantly increased in spinal dorsal horn of CFA rats.Moreover,it was observed that pJNK was almost entirely expressed in astrocytes.(3) Western Blot data revealed that the expression levels of GFAP and pJNK were significantly increased in CFA rats,and i.p.injection of 8-OaS could obviously inhibit the activation of astrocytes and pJNK (P ＜ 0.01).Conclusion:i.p.administration of 8-OaS can significantly attenuate CFA-induced mechanical allodynia.The underlying mechanism of the potential analgesia effect of 8-OaS iscontributedto the suppression of phosphorylation of pJNK and the activation of astrocytes.