神經移植後之研究末梢組織神經再生及神經滋養因子表現

Abstract

在外傷或腫瘤切除後的神經缺損，常需利用神經移植手術來重建神經的功能。而在神經移植後，末梢組織神經再生決定了最後功能的恢復。之前研究神經功能的恢復程度主要是根據切片形態學來做評估，很少研究是根據末梢神經再生來探討功能恢復程度。我們利用小鼠神經移植手術模式來研究各種末梢組織的神經再生及神經滋養因子表現。手術方式是將小鼠右側的坐骨神經切一段下來，然後再利用顯微手術，將神經原位縫回去。我們利用神經再生指數來做各種末梢組織神經再生的比較，神經再生指數的定義是手術側的神經定量數據除以對照側的神經定量數據。另外我們利用逆轉錄-聚合酶反應(RT-PCR)來定量小鼠足墊皮膚及足底肌肉各種神經滋養因子信使RNA表現的量。在手術後3個月，足底肌肉的神經再生比皮膚的神經再生好(P<0.0001)，也比汗腺自律神經好(P<0.0001)。汗腺自律神經再生也比皮膚的神經再生好(P=0.014)。逆轉錄-聚合酶反應(RT-PCR)定量神經滋養因子信使RNA顯示足底肌肉的腦源性神經滋養因子(brain-derived neurotrophic factor, BDNF)、神經膠質細胞來源神經滋養因子(glial cell line-derived neurotrophic factor , GDNF)、神經滋養因子3(neurotrophin 3, NT3) 信使RNA 在手術側較高。相對的在小鼠足墊皮膚各種神經滋養因子信使RNA的量在手術側及對照側都相類似。在神經移植後，相對於皮膚而言，足底肌肉達到最好的神經再生。這可能是因為BDNF、GDNF、NT3在肌肉有較大量的表現。

Reinnervation of target tissues determines functional outcomes after nerve grafting, which is important in traumatic injury due to accidents or consequences due to surgical removal of tumors. Previous studies documented the influences of nerve repair mainly based on nerve morphometry but rarely compared the final outcomes according to target reinnervation patterns by nerve fibers of different categories. To study the differences in target reinnervation and expression patterns of trophic factors in target tissues, we used a mouse model of sciatic nerve graft. We analyzed the innervation indexes of different target tissues after transection-reimplantation on the sciatic nerve, which were defined as a parameter on the operated side normalized to that on the control side. A reverse-transcription polymerase chain reaction (RT-PCR) was performed in the footpad skin and plantar muscle to study mRA expression of various neurotrophins. The results of target reinnervation quantification showed that muscle reinnervation appeared to be the best compared to the skin reinnervation (p < 0.0001) and sweat gland reinnervation (p < 0.0001) at postoperative month 3. The sudomotor reinnervation was relatively higher than the cutaneous reinnervation (p = 0.014). The abundance of trophin transcripts for brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and neurotrophin 3 (NT3) was higher in plantar muscles on the operated side than that on the control side. In contrast, transcripts of BDNF, GDNF, nerve growth factor, and NT3 were all similar in the footpad skin between the operated and control sides. The study results suggested that compared to the skin, muscles achieved the best reinnervation after nerve grafting which was related to higher expressions of BDNF, GDNF, and NT3 in muscles than the skin.