A Study On Facial Motorneurons Death And Its Regulatory Gene Expression Following Facial Nerve Injury

Objective To investigate the morphology of facial motorneurons and the expression of Bcl-2 p~53 following facial nerve transection or crush at its stylomastoid foramen in SD rats. At the same time, to explore the role of applied medicine Minocycline in the recovery of facial nerve's function and the protection to its motorneurons after facial nerve injury. Method 65 rats were divided into three groups randomly: the group I: the left facial nerves in 30 rats were transected at its stylomastoid foramen while the right crushed; the group II: Minocycline was applied in another 30 rats after its facial nerves were injured as the group I; the group III: all of 5 rats were not performed any injury. The morphology of facial motorneurons was observed after facial nerve injury by using HE staining. Moreover, the expression of BCL-2 and p53 protein in facial motorneurons was also analyzed by using the method PowerVision Two-Step immunohisto — chemical staining. Result (1) Facial nerve crush did not result in the death of facial motorneurons; (2) Facial nerve transection could lead to the death of its motorneurons. The number of motorneurons in the two groups (I II) was obviously less than that of the group III. (3) Minocycline could promote the rapid recovery of crushed facial nerve. In addition, the protective function of Minocycline to facial motorneurons was observed following facial nerve transaction. (4) The expression of BCL-2 and p53 following facial nerve transaction was significantly higher than those of normal control group III throughout the experiment. Conclusion (1) There is a relationship between facial motorneurons apoptosis and the patterns of facial nerve injuries. Facial nerve transection can resultin the death of motorneurons. (2) Minocycline can promote the rapid recovery of the crushed facial nerve and obviously prevent facial motorneurons from dying after transaction as well. (3) BCL-2 and p53 genes might play a great role in the process of facial motorneurons apoptosis following facial nerve transection, the ratio of BCL-2 / p53may control facial motorneurons apoptosis.