Objectives: To explore the effect of intrathecal administration of exogenous noggin (NOG) on the pain behavior in the neuropathic pain (NP) rats through L5 spinal nerve ligation (SNL), and to examine the regulative role of NOG in astrocyte activation, inflammatory cytokines and downstream signals.
Methods: A total of 40 adult male Sprague Dawley (SD) rats were randomly divided into 3 groups: a control group (n=10), a SNL group (SNL+intrathecal injection of artificial cerebrospinal fluid, n=15), and a SNL+NOG group (SNL+intrathecal injection of recombinant NOG protein, n=15). Von-Frey filaments were used to test the changes of paw withdrawal threshold (PWT) at Day 1 before operation, and Day 1, Day 4, Day 7 and Day 14 after operation in each group. Immunofluorescence was used to observe the activation of astrocyte located in the dorsal horn of spinal cord in the 3 groups. Western blotting was conducted to detect the expression levels of glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), signal transducer and activator of transcription (STAT3) and phosphorylation STAT3 (p-STAT3).
Results: Compared with the control group, the PWT in the SNL group was markedly decreased at each time point, together with the increase in GFAP, IL-6 and the ratio of p-STAT3/STAT3 (all P<0.05). Meanwhile, compared with the SNL group, the PWT in the lumbar swelling of spinal cord in the SNL+NOG group was elevated at Day 4 and lasted to Day 14 (P<0.05), accompanied by the decrease in GFAP, IL-6 and the ratio of p-STAT3/STAT3 (all P<0.05).
Conclusions: The intrathecal administration of NOG may alleviate NP in the SNL rats through inhibiting astrocyte activation and down-regulating the STAT3 signal pathway.
目的: 观察鞘内给予外源性头蛋白(noggin，NOG)对腰5脊神经结扎(L5 spinal nerve ligation，SNL)致神经病理性疼痛(neuropathic pain，NP)大鼠疼痛行为学的影响，并同时检测NOG对脊髓内星形胶质细胞活性、炎性因子及下游信号的调控作用。方法: 40只雄性Sprague Dawley大鼠随机分为空白对照组(n=10)、SNL组(暴露并结扎L5脊神经+鞘内给予人工脑脊液，n=15)和SNL+NOG组(暴露并结扎L5脊神经+鞘内给予NOG，n=15)。使用Von-Frey测痛纤维检测手术前1天及术后第1，4，7，14天每组大鼠后足机械缩足阈值(paw withdrawal threshold，PWT)的改变；应用免疫荧光法观察各组大鼠术后第7天脊髓背角处星形胶质细胞的激活情况；应用蛋白质印迹法观察各组大鼠术后第7和14天脊髓内胶质细胞原纤维酸性蛋白(glial fibrillary acidic protein，GFAP)、白细胞介素-6 (interleukin-6，IL-6)、转录信号转导剂和激活剂-3(signal transducer and activator of transcription 3，STAT3)以及磷酸化STAT3(p-STAT3)的表达。结果: 与空白对照组相比，SNL组术后各时点PWT均明显下降，同时伴有脊髓腰膨大处GFAP、IL-6的表达及p-STAT3/STAT3的比率明显升高(均P<0.05)；与SNL组相比，SNL+NOG组在术后第4天出现PWT上升(P<0.05)，并维持至术后第14天，且同时伴有脊髓腰膨大内GFAP、IL-6的表达及p-STAT3/STAT3比率显著降低(均P<0.05)。结论: 鞘内给予外源性NOG能够缓解SNL大鼠痛觉过敏的症状，这与降低星形胶质细胞活性、减轻IL-6的表达以及下调STAT3信号通路的激活有关。.
Keywords: astrocyte activation; bone morphogenetic proteins; neuropathic pain; noggin; signal transducer and activator of transcription 3.