Dynamic change of myogenin in denervated rat mimetic muscle.

We previously reported double innervation of rat mimetic muscles with labeling of facial nuclei. However, whether denervated mimetic muscles are affected after such nerve repair is not known. Rats were divided into five groups: Group A, controls; Group B, complete facial palsy; Group C, complete facial palsy with repair using end-to-end neurorrhaphy; Group D, incomplete facial palsy; and Group E, incomplete facial palsy with repair using end-to-side neurorrhaphy. Preoperatively and postoperatively, facial palsy and myogenin (Myog) expression in mimetic muscles were evaluated. Expression peaked on day 7 in Group B but was lower in Groups C and D. Expression in Groups D and E was comparable on day 28, and each model's score showed characteristic changes. Myog expression in facial mimetic muscles increases with denervation and decreases with nerve repair. Determining Myog expression levels in mimetic muscles just after nerve repair may help surgeons predict postoperative prognosis in facial palsy.