[Facial paralysis induced by herpes simplex virus type 1 and the study of facial neurons apoptosis in mice].

Objective: To study the apoptosis of facial motor neurons and the expression of apoptosis-related genes, Bcl-2 and Bax, in the animal model of viral facial paralysis.

Methods: Total of 84 Balb/c mice were divided into viral inoculation group and nerve transaction group. The animals were executed 1, 3, 7, 10, 15, 20 and 30 days after being operated respectively. The histopathological features of facial neurons in brain stem were observed by HE and Nissl stain. The changes of facial neuronal apoptosis were observed by TUNEL. The changes of expression of Bcl-2 and Bax genes in facial neurons were observed by immunohistochemistry staining.

Results: After nerve transection, increased apoptotic cells were found in homolateral facial motor nucleus and the peak appeared at 10 and 15 days. The level of Bcl-2 expression in neurons declined while the expression of Bax increased gradually. Correspondingly, the ratio of Bcl-2/Bax declined. In the viral inoculation group, no visible change of apoptosis and Bax expression, but the level of Bcl-2 and the ratio of Bcl-2/Bax increased gradually.

Conclusions: Comparing to axotomy, facial motor nucleus in HSV-1 infective animal model are free of apoptosis. Both the mild form of lesion and the ability to block apoptosis of HSV-1 are likely to be involved into the phenomenon. Bcl-2 and Bax might interfere with the apoptotic response.