生长分化因子15对福尔马林诱导双相疼痛的镇痛作用及机制的初步探究

Antinociceptive effect and mechanism of growth differentiation factor 15 on formalin-induced pain in mice

目的:探讨生长分化因子15(growth differentiation factor 15,GDF-15)对福尔马林诱导的双相疼痛的镇痛作用及其可能机制。方法:首先采用中枢给药鞘内注射GDF-15(50 ng)进行了福尔马林诱导双相疼痛实验,并设置不同剂量组系统性腹腔注射GDF-15(10、30、100μg/kg)进行福尔马林诱导双相疼痛实验,记录比较福尔马林诱导双相疼痛阈值;采用蛋白免疫印迹和组织免疫荧光实验检验GDF-15的特异性受体胶质细胞源性神经营养因子家族α样受体(glial cell-line derived neurotrophic factor receptor alpha-like,GFRAL)的表达情况;并采用实时荧光PCR法检测中枢给予GDF-15(50 ng)对福尔马林小鼠脊髓白细胞介素(interleukin,IL)-6、IL-1β、肿瘤坏死因子(tumor necrosis factor,TNF)-α、强啡肽原(prodynorphin,PDYN)以及前脑啡肽(proenkephalin,PENK)的mRNA表达的影响。结果:中枢给予GDF-15对福尔马林Ⅱ相炎性疼痛有显著镇痛作用,而对Ⅰ相急性疼痛未见显著作用(P<0.05);系统性给予GDF-15对福尔马林Ⅱ相炎性疼痛有显著镇痛作用(P<0.05),且呈剂量依赖性;GDF-15的特异性受体GFRAL在大脑、小脑和脊髓中表达,在脊髓背角中仅在神经元细胞表达;中枢给予GDF-15可以降低福尔马林小鼠脊髓中促炎因子IL-6(P<0.05)和TNF-α(P<0.05)的表达。结论:GDF-15对福尔马林诱导的Ⅱ相炎性疼痛存在镇痛作用,且可能是通过降低促炎因子IL-6和TNF-α的表达发挥作用。

Objective:The current study intended to examine the antinociceptive effect of growth differentiation factor 15(GDF-15)and to elucidate its possible mechanism of action.Methods:Mice formalin-induced pain model with intrathecal administration of GDF-15(50 ng)and intraperitoneal administration of GDF-15(10,30,100μg/kg)was used in this study to examine the antinociceptive effect of GDF-15.The expression of glial cell-line derived neurotrophic factor receptor alpha-like(GFRAL)which is considered to be the specific receptor of GDF-15 was assessed using Western blot and immunofluorescence techniques.The expression of interleukin(IL)-6,IL-1β,tumor necrosis factor(TNF)-α,prodynorphin(PDYN)and proenkephalin(PENK)in the formalin micespinal cords was also evaluated.Results:Intrathecal administration of GDF-15(50 ng)showed a significant antinociceptive effect informalin-induced tonic pain(P<0.05)but not in formalin-induced acute pain.Intraperitoneal administration of GDF-15(10,30,100μg/kg)produced a dose-dependent antinociceptive effect in mice formalin-induced tonic pain.GFRAL was expressed in brain,cerebellum and spinal cord,and only in neurons of the spinal cord dorsal horn.Moreover,intrathecal injection of GDF-15 inhibited the expression of proinflammatory mediators IL-6(P<0.05)and TNF-α(P<0.05)in the spinal cord of formalin mice.Conclusion:GDF-15 exhibits a significant antinociceptive effect in formalin-induced inflammatory hyperalgesia and its possible mechanism may be by reducing the expression of pro-inflammatory factors IL-6 and TNF-α.