cAMP反应元件结合蛋白介导磷酸化细胞外信号调节激酶在神经病理性痛形成中的作用

采用行为学、免疫组织化学和Western blot方法,观察鞘内注射细胞外信号调节激酶(extracellular signal-regulate kinase,ERK)信号转导通路阻滞剂对慢性压迫性损伤(chronic constriction injury,CCI)大鼠痛行为及脊髓背角内磷酸化cAMP反应元件结合蛋白(phosphorylated cAMP response-element binding protein,pCREB)和Fos表达变化的影响,探讨ERK／CREB转导通路在神经病理性疼痛中的作用。结果表明,CCI可明显增加双侧脊髓背角pCREB、损伤侧脊髓背角浅层Fos阳性神经元表达,以CCI后3与5d时尤为显著。鞘内沣射促分裂原活化蛋白激酶激酶(mitogen-activated protein kinase kinase,MEK)阻滞剂U0126及ERK反义寡核苷酸在减轻大鼠痛行为的同时,能明显抑制双侧脊髓背角内pCREB的表达,同时,Fos阳性神经元的表达也明显减少。大鼠痛行为及脊髓背角pCREB和Fos的表达在时相上一致。上述结果提示pCREB参与pERK介导的神经病理性疼痛。

cAMP response-element binding protein participates in the phosphorylated extracellular signal-regulate kinase mediated neuropathic pain

It has been reported that extracellular signal-regulate kinase (ERK) is involved in the modulation of nociceptive information and central sensitization produced by intense noxious stimuli and/or peripheral tissue inflammation. Few studies have explored the relationship between ERK and cAMP response-element binding protein (CREB) in neuropathic pain after nerve injury, such as chronic constriction injury (CCI) of the sciatic nerve. In the present study, CCI model was employed to investigate the activation of ERK on the expression of phosphorylated CREB (pCREB) in chronic neuropathic pain. Lumbar intrathecal catheters were chronically implanted in male Sprague-Dawley rats. The left sciatic nerve was loosely ligated proximal to the sciatica's trifurcation at around 1.0- mm intervals with 4-0 silk suture. Mitogen-activated protein kinase kinase (MEK) inhibitor U0126 and phosphorothioate-modified antisense oligonucleotides (ODN) were intrathecally administered one day before and three consecutive days after CCI. Thermal and mechanical nociceptive thresholds were assessed with the paw withdrawal lantency (PWL) to radiant heat and von Frey filaments respectively. The expression of pCREB and Fos were assessed by both Western blot and immunohistochemical analysis. The results showed that intrathecal injection of U0126 or ERK antisense ODN attenuated significantly CCI-induced mechanical and thermal hyperalgesia. Correlating with behavior results, the injection also markedly suppressed the increase of CCI-induced pCREB and c-Fos expression. The results obtained suggest that CREB participates in the pERK-mediated neuropathic pain.