觀察小鼠在施打奧沙力鉑後引起的疼痛反應以及周邊神經變化

Abstract

周邊神經病變(peripheral neuropathy) 所引起的神經性疼痛 (neuropathic pain)會嚴重影響病患的生活品質，常見於疾病的症狀或者治療的副作用，例如：糖尿病患者晚期的慢性疼痛，以及癌症化療造成的末肢疼痛。無論是在臨床或是實驗室中，只有少數方法可用於了解末梢神經纖維狀況，如組織切片(tissue biopsy)或定量感覺測試(Quantitative sensory testing)。這些方法皆有其自身的缺陷和局限，例如：造成開放性傷口，或只能觀察行為間接獲得周邊神經的健康狀況。 本研究基於我們實驗室使用的Nav1.8-cre-Tdtomato小鼠和共聚焦顯微鏡所發展而成的方法，有別於傳統活體組織切片或者以測定行為等間接的方式去了解周邊神經的狀況，此方式不僅可以在不造成開放性傷口的情況下直接觀察周圍神經纖維在皮下的狀態，還可以在特定皮膚區域在不同時間點進行連續的實時追蹤。結合癌症化療藥物奧沙利鉑引起的疼痛模型，本實驗目標在於以活體實時觀察周邊皮下神經纖維之方式研究奧沙利鉑引起的異常疼痛與皮下感覺神經型態學上的干係。 在施打了奧沙利鉑後，在曠野實驗中小鼠移動距離明顯下降，且在機械痛實驗中施打奧沙利鉑的小鼠有明顯疼痛，然而小鼠後腳皮下鈉離子電位感測型通道1.8表現型(Nav1.8)有表現的神經不論是長度或是體積皆沒有顯著性變化。本篇發現化療引起的機械性疼痛不是由於皮下感覺神經退化所引起，可能造成異常疼痛的原因有細胞膜上膜離子通道表現型改變進而造成痛覺異常等。

Neuropathic pain caused by peripheral neuropathy can severely affect the patient's quality of life. It is often found in the disease symptoms or medical treatment side effects, such as chronic pain in the advanced stages of diabetes and cancer chemotherapy neuropathic pain. Neither clinical or laboratory, only few methods can exam terminal neuron fibres status, like tissue biopsy or Quantitative sensory testing (QST). All these methods have its own defects and limits, such as skin damage and indirectly approaching. This study is based on a method developed by the Nav1.8-cre-Tdtomato mouse and confocal microscope used in our laboratory. Our method not only directly observe the state of the peripheral nerve fibres under the skin without causing an open wound, but also continuously track in real time at different time points in specific skin area. After oxaliplatin injection, mouse behavior changed but nerve morphology remained consistent. In open field test, locomotor activities droped in week 2 and 3. Anxiety also developed after oxaliplatin treatment. In von Frey test, mice developed severe mechanical allodynia in week 1, 2, and 3. By our in vivo image, results show either Nav1.8 expressed cutaneous nerve length or volume remained consistent under oxaliplatin treatment. All results indicate that oxaliplatin induced mechanical allodynia has no relation with cutaneous nerves morphology change. Mechanical allodynia may be caused by remodeling expression of ion channels or oxidative stress in cell body, which we cannot approach by this method.