神經壓迫傷害的解除對於疼痛覺行為, 表皮感覺神經再支配和脊髓內神經細胞胞外訊息調節激酶（ERK）表現的影響

Effects of decompression on neuropathic pain behaviors, skin reinnervation and ERK expression in the spinal cord in chronic constriction injury

曾拓榮(To-Jung Tseng)

指導教授 ： 謝松蒼

國立臺灣大學/醫學院/解剖學研究所/博士(2007年)

https://doi.org/10.6342/NTU.2007.00343

摘要

神經受傷所引起的疼痛覺敏感的行為反應 (Neuropathic pain behaviors) 與背根神經節 (Dorsal root ganglia) 內神經細胞的周邊和中樞神經軸突的表現有關，包括皮膚內的神經支配 (Skin innervation) 和脊髓背角的可塑性 (Dorsal horn plasticity)。在臨床應用上，解除神經壓迫可以舒緩神經病變引起的疼痛反應；然而，實驗設計上缺乏動物模式探討神經受傷後產生的疼痛行為在時間軸上的變化性以及其對於感覺神經再生到標的物的影響。我們建立了大鼠在慢性壓迫神經傷害 (Chronic constriction injury (CCI)) 並且移除壓迫物質的動物模式，實驗區分成兩群 (Decompression group and CCI group) 來探討在手術後第四週移除壓迫物質與否的差異性。我們對於此影響進一步比較：(1)皮膚內的神經支配指數 (Skin innervation index)：表皮內神經密度比值 (Epidermal nerve densities: operated/contralateral side)；(2)脊髓背角內神經細胞表現活化性胞外訊息調節激酶的指數 (Dorsal horn index of extracellular signal-regulated kinase (ERK) activation)，脊髓背角內表現活化性胞外訊息調節激酶的神經細胞比值 (The number of phosphorylated ERK (+) cells: operated/contralateral side)。兩群動物在手術後第四週時顯示熱覺過敏 (Thermal hyperalgesia) 和機械性刺激敏感 (Mechanical allodynia) 現象，並且在Skin innervation index (protein gene product 9.5 (PGP 9.5), substance P (SP), and calcitonin gene-related peptide (CGRP)) 的評估上顯示兩群動物在受傷側表現相似的神經退化程度；然而，Dorsal horn index of ERK activation則顯示在兩群動物中在受傷側的脊髓背角內表現活化性胞外訊息調節激酶的神經細胞數目皆增加。Decompression group從手術後六週開始對於熱覺過敏與機械性刺激敏感現象有減緩的趨勢，並且在手術後第八週時顯示疼痛覺反應行為完全消失。Skin innervation index (SP) 亦顯示增加的趨勢，但是Skin innervation index (PGP 9.5, CGRP) 在兩群動物間則無顯著差異。Decompression group在手術後第八週時顯示Dorsal horn index of ERK activation回復到正常表現數值，CCI group則顯示較高的指數並且仍然具有疼痛覺敏感的行為現象。針對長期性的疼痛覺自然回復現象，發現CCI group在手術後第十二週疼痛行為反應消失並且在Dorsal horn index of ERK activation亦回復到正常表現數值。雖然Decompression group在手術後第二十四週比CCI group顯示較佳的Skin innervation index (PGP 9.5)，可是對於正常皮膚神經支配卻仍然表示不完全的皮膚神經再支配現象。這些結果說明了移除神經壓迫源可以(1)加速疼痛覺行為的消失，(2)皮膚內表現SP的神經再支配現象較佳，(3)在長期的觀察中，皮膚內表現PGP 9.5的神經具有較優的再支配性，(3)脊髓背角內表現活化胞外訊息調節激酶的神經細胞數目減少並回復正常；雖然CCI group的疼痛覺行為消失時間較晚，此時脊髓背角內表現活化胞外訊息調節激酶的神經細胞數目趨於正常，然而，皮膚內表現PGP 9.5的神經再支配現象仍受限制。

關鍵字

受傷引起的神經疼痛 ； 慢性壓迫神經傷害 ； 解除壓迫手術 ； 皮膚內神經支配 ； 物質 P ； 降血鈣素基因調節胜肽胞外訊息調節激酶

並列摘要

Injury-induced neuropathic pain behaviors is related to changes in peripheral and central terminals of dorsal root ganglia neurons, i.e. skin innervation and dorsal horn plasticity. Decompression is an important therapeutic strategy to relieve neuropathic pain clinically; there is, however, lack of animal models to study its temporal course of neuropathic pain behaviors and its influence on nerve regeneration to sensory targets. To address these issues, we established a model of decompression on rats with chronic constriction injury (CCI) and investigated the influences of decompression by removing ligatures at postoperative week (POW 4), the decompression group; for comparison, all ligatures remained through the experimental period in the CCI group. The effects were compared with (1) skin innervation index, a ratio (operated/contralateral side) of epidermal nerve densities and (2) dorsal horn index of extracellular signal-regulated kinase (ERK) activation, a ratio (operated/contralateral side) of the number of phosphorylated ERK (+) cells in the dorsal horn. At POW 4, both groups exhibited thermal hyperalgesia and mechanical allodynia and the skin innervation indexes of protein gene product 9.5 (PGP 9.5), substance P (SP), and calcitonin gene-related peptide (CGRP) were reduced to similar degrees, however, the dorsal horn indexes of extracellular signal-regulated kinase (ERK) activation had increased to a similar degree in both groups. Beginning from POW 6, the decompression group exhibited significant reductions of thermal hyperalgesia and mechanical allodynia compared to the CCI group (p < 0.001). At POW 8, neuropathic pain behaviors had completely disappeared in the decompression group, and had a higher skin innervation index of SP than the CCI group (0.45 ± 0.05 vs. 0.16 ± 0.03, p < 0.001). These indexes were similar in both groups for PGP 9.5 (0.32 ± 0.09 vs. 0.14 ± 0.04, p = 0.11) and CGRP (0.38 ± 0.06 vs. 0.21 ± 0.07, p = 0.09). At POW 8, the animals with a normalization of dorsal horn index (1.17 ± 0.11 vs. 1.02 ± 0.12 at POW 0, p = 0.071) in the decompression group; the dorsal horn index remained elevated in the CCI group (2.48 ± 0.30, p < 0.001) with persistent neuropathic pain behaviors. The CCI group showed a delay in the normalization of neuropathic pain behaviors at POW 12. In the CCI group, the elevation of the dorsal horn index had reversed (1.30 ± 0.09 vs. 1.06 ± 0.14 at POW 0, p = 0.14). Although the decompression group had a higher skin innervation index of PGP 9.5 than the CCI group at POW 24 (0.59 ± 0.13 vs. 0.34 ± 0.13, p < 0.05), skin reinnervation remained incomplete after decompression compared to the baseline skin innervation index of PGP 9.5 (1.04 ± 0.10 at POW 0, p < 0.001). These findings demonstrate the temporal changes in the disappearance of neuropathic pain behaviors after decompression and suggest that decompression causes different patterns of skin reinnervation for different markers of skin innervation and normalization of ERK activation in the dorsal horn.

並列關鍵字

Injury-induced neuropathic pain ； Chronic constriction injury ； Surgical decompression ； Skin innervation ； Substance P ； Calcitonin gene-related peptide ； Extracellular signal-regulated kinase

參考文獻

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The spectrum of fiber loss in a model of neuropathic pain in the rat: an electron microscopic study.

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Putting the spinal cord together again.