Role of nitric oxide in facial nerve paralysis in mice induced by herpes simplex type 1 infection

本研究旨在阐明一氧化氮(NO)在单纯疱疹病毒1型(HSV-1)感染诱发面瘫中的作用，并评价依达拉奉预防病毒源面瘫的作用。用高效液相色谱分光光度法测定面神经组织中NO的含量。在面瘫发生前，接种HSV-1的一侧(右侧)和对照侧(左侧)之间的NO水平没有显著差异。面神经麻痹发生时，瘫痪侧的NO水平高于对侧。面瘫恢复后，双侧均未达到同一水平。在接种HSV-1但未发生面神经麻痹的小鼠中，两侧NO水平相同。激光共聚焦显微镜免疫组织化学研究显示，面神经麻痹动物膝状神经节的炎性细胞中可见诱导型一氧化氮合酶(INOS)。仅在患侧瘫痪时才能识别，对侧不识别。在接种HSV-1后立即给予自由基清除剂依达拉奉，最长达11天。结果表明，依达拉奉10 mg/kg能有效降低面瘫的发生率。综上所述，一氧化氮可能通过诱导型一氧化氮合酶在膝状神经节产生，在单纯疱疹病毒1型诱发面瘫的过程中起重要作用，而依达拉朋可预防这种损伤。

The present study was under gone to elucidate a role of nitric oxide (NO) on induction of facial palsy by inoculation of herpes simplex type 1 (HSV-1), and to evaluate the effects of edarabone to prevent occurrence of facial palsy of the viral origin. NO levels of in the facial nerve were measured by use of a high performance liquid chromatography and absorption photometry. Before the incidence of facial palsy, no substantial difference in NO levels was noted between HSV-1 inoculated sides (right) and the control (left) sides. When the facial nerve palsy occurred, NO levels of the paralyzed side were higher than of the other side. Following recovery of the palsy, NO of both sides were at the same level. In the mice that facial nerve paralysis did not occur in spite of inoculation of HSV-1, NO of both sides were at the same level. According to immunohistological study using the confocal laser microscope, inducible nitric oxide synthase (iNOS) was observed in the inflammatory cells at the geniculate ganglion in animals with facial palsy presents. It was recognized only at the involved paralyzed side not at the contralateral side. Edarabone, a free radical scavenger, was administed to the animals immediately after inoculation of HSV-1 for as long as 11 days. The results indicated that 10mg/kg of edarabone was effective in reducing the incidence of facial palsy. In conclusion, NO, which is supposed to be produced at the geniculate ganglion via iNOS, plays an important role in induction of facial palsy by HSV-1, and, such damages may be prevented by use of edarabone.