Neuroprotective Effect Of Rhepo On Facial Motoneurons After Facial Nerve Injury In Rats

Objective: To observe the neuroprotective effect of rhEPO on injuried facial motoneurons(FMNs) and its impact on the esspression of Caspase-3.Methods: The rat modeIs of faciaI nerve injury were established by crashing main trunk of the left facial nerve.75 female rats were randomly divided into 3 groups: rhEPO treatment group(treated with rhEPO 5000U/kg ip once a day following injury for two weeks,n=25), control group(treated with the same dose of normal saline ip once a day following injury for two weeks,n=25) ,sham operation group(n=25).Rats were sacrificed 3,7,14,21,28d after injury.The survival of FMNs after facial nerve injury was studied by Toluidine blue staining.The apoptosis of the injured FMNs was detected by TUNEL staining.The expression of Caspase-3 were detected by immunohistochemistry method.Results: (1)The survival rates of FMNs both in rhEPO treatment group and control group decreased gradually from 7d to 28d, the survival rates of FMNs in rhEPO treatment group were significantly higher than that in control group(P<0.05)(.2) No TUNEL-positive cells were observed 3d after injury both in rhEPO treatment group and control group,but noted on 7d after injury and the number peaked at 14d in control group. The apoptotic cell numbers in the rhEPO treatment group were significantly lower than that in control group from 7d to 21d(P<0.05).(3) The expression of Caspase-3 increased 3d after injury and peaked at 14d in control group. The expression level of Caspase-3 in rhEPO treatment group was significantly lower than that in control group at each time point(P<0.05).(4)The rats'palp of control group began to move slightly without the action of closing eyes at 18d,a part of rat'palp recovered forward,it could move rhythmicly,but the amplitude and velocity of the movement were abnormal,these rats could not close eyes completely at 28d. The rats'palp of treatment group began to move slightly with the movement of palpebra superior at 18d, the movement of rats palp approached to normal in treatment group,the rats could close eyes completely at 28dConclusion: rhEPO can effectively protect facial motoneurons and reduce the expression of Caspase-3 after facial nerve injury; apoptosis inhibition and decreased expression of Caspase-3 by rhEPO may be an important mechanism for treatment of traumatic facial paralysis.