G-CSF對慢性結紮損傷模式所引起的神經變異性疼痛之影響

Abstract

神經變異性疼痛為神經受損所引起的一種慢性疼痛現象，會嚴重影響病患的生活品質，目前並無有效的治療方法。近期研究結果顯示，顆粒細胞生長因子 ( G-CSF ) 會促進一種名為 PMN 細胞的白血球增生，由於這種白血球會分泌類鴉片物質。故我們假設使用 G-CSF 後，增生的 PMN 細胞分泌的類鴉片物質具有減輕疼痛的效果。本實驗利用慢性綑綁模式 ( CCI )，來達到模擬神經變異性疼痛的效果，手術前先注射 G-CSF ( 0.7 mg/kg, i.v. )，再進行行為測試，包括熱敏感與觸覺兩項實驗。而結果顯示未注射 G-CSF 的組別對熱水和壓力的承受力均下降，而注射 G-CSF 組別對熱水和壓力的承受力均趨近於未受傷的組別，顯示 G-CSF 確實擁有減輕疼痛的效果。利用流式細胞儀和免疫染色觀察坐骨神經的細胞切片或其組織液，發現注射 G-CSF 的組別其 PMN 細胞或能分泌類鴉片物質的 PMN 細胞確實有增加，而且能侵入受傷神經內，這個結果符合我們的假設，即 G-CSF 的藥效來自 PMN 細胞所分泌的類鴉片物質。另外我們又利用 SQ-RT-PCR 來了解 G-CSF 是否影響前發炎細胞激素的表現。結果顯示注射 G-CSF 組別其 IL-1β 和 IL-6 的表現量顯著下降，故我們推論 G-CSF 不僅是透過 PMN 細胞分泌的類鴉片物質，還可能透過抑制 IL-1β 和 IL-6 表現來抑制發炎反應產生，進而抑制了由發炎反應所引起的神經變異性疼痛。Neuropathic pain is due to long-term dysfunction of the nervous system and is difficult to managements and treatments. Under inflammatory conditions, leukocytes secrete opioid peptides, which bind to opioid receptors on peripheral sensory neurons and mediate antinociception. The majority of opioid-containing leukocytes are PMN during early inflammation. Granulocyte-colony stimulating factor (G-CSF) is a particular growth factor that works by encouraging the bone marrow to produce more stem cells which then differentiate into white blood cells, especially the PMN. Therefore, G-CSF has a potential to become an anti-nociceptive agent. In the study we use chronic constriction injury model to produce neuropathic pain in rats with nerve injury. Thereafter, we performed behavior tests including thermal and mechanical responses. Our results indicated the experimental group with i.v. G-CSF showed less severe neuropathic pain than control with normal saline within 2 days post-operation. In flow cytometry and immuno-histochemical studies the numbers of PMN cells around sciatic nerve in the group with G-CSF treatment showed much more than the control group. The results demonstrated the effects of G-CSF on neuropathic pain are probably through the opioid compounds secreted by PMN cells. Besides, we find that G-CSF maybe inhabit the expression of several proinflammatory cytokine, like IL-1β and IL-6 by SQ-RT-PCR. So the mechanism of G-CSF to save pain may not only due to the opioid compound secreted by PMN cells but inhabit the expression of IL-1βand IL-6 to suppress the inflammatory and neuropathic pain.