High dose erythropoietin promotes functional recovery of rats following facial nerve crush.

Erythropoietin (Epo) has neuroprotective activity in a variety of settings. Thus, we investigated whether Epo has a role in the functional recovery of rats after facial nerve injury. The right facial nerve of 24 Wistar rats (6 wks old) was crushed twice at the level of the stylomastoid foramen, for 30 s each time, using jeweler's forceps held perpendicular to the nerve. The left facial nerve did not undergo the surgical lesion. The rats were randomly divided into 4 groups: (group 1) the control group (placebo, treated with saline); and groups treated with Epo at a dose of 1,000 U/kg body weight (group 2), 5,000 U/kg body weight (group 3), and 10,000 U/kg body weight (group 4). The Epo and saline were administered subcutaneously pre-operatively and treatment was repeated every 24 h for the first 2 weeks after the operation. Behavioral recovery from facial paralysis was measured daily, beginning 1 day after surgery, until full recovery of the eye blink reflex and whisker movements were observed. The average recovery times for the full blink reflex and whisker movements were significantly shorter (about 2-3 days) in rats treated with a high dose Epo (5,000, 10,000 U/kg body weight) compared to the placebo-treated rats (p<0.05). There was no significant difference between low dose Epo-treated rats (1,000 U/kg body weight) and the placebo-treated rats. These results suggest that high dose Epo can promote the functional recovery of rats following facial nerve injury. Further studies are warranted to probe alternative treatment schedules (dose, mode of administration), underlying histological mechanisms and combination treatment with additional neuroprotective factors.