Dynamic expression of the neurotrophic factor IV in the rat model of facial nerve injury

Objective To evaluate dynamic expression changes of neurotrophin-4(NT-4)in the rat facial nerve,vibrissae muscle and facial nucleus in response to facial nerve injury.Methods A rat model of facial nerve injury was established.Subsequently,all facial nerves,the vibrissae muscle and pons were taken out on days 1,3,7,14,and 21 after injury.Expression of NT-4 mRNA was detected by RT-PCR.Expression of NT-4 at the protein level was simultaneously determined by Western blot and immunohistochemisty.Results Expression of NT-4 was detected in the facial nerve,vibrissae muscle and facial nucleus.Expression of NT-4 was elevated and reached a peak at 14th day in the facial nerve and facial nucleus,whereas it was reduced in the muscle.Conclusions Expression of NT-4 was increased in the facial nerve and nucleus and decreased in the vibrissae muscle after facial nerve injury.These indicate that expression of NT-4 in the nerve tissue could be closely related to the injury in the facial nerve.