The effectiveness of different neuroprotective agents in facial nerve injury: An experimental study

Objectives/Hypothesis To examine and compare the neuroprotective effects of dexamethasone, oxytocin, and resveratrol administration on regeneration after facial nerve crush injury in a rat model. Study Design Prospective, randomized, controlled animal study. Methods A crush-type facial nerve injury was performed on the right side of all rats (injury group [IG]), whereas there was no injury on the left side (sham group [SG]). These main groups were divided into five subgroups: 1) no medicine (control); 2) physiological serum; 3) dexamethasone; 4) oxytocin; and 5) resveratrol (Res) administered (intraperitoneal injection) for 28 days. Functional recovery was evaluated by daily eye-blink reflex and facial electromyography. Nerve-muscle degeneration and regeneration, apoptosis, and intercellular connections were evaluated in histopathological and immunohistochemical examinations. Results Recovery time of the postinjury eye-blink reflex demonstrated faster recovery in IG + Res when compared with the other subgroups. In peak-to-peak amplitude values, a significant increase was observed in the dexamethasone (P = 0.007) and oxytocin subgroups (P = 0.004) and was even more apparent in the resveratrol subgroup (P < 0.001). Nerve regeneration is apparent in the resveratrol subgroup. Apoptotic changes were evaluated immunohistochemically with TUNEL and Caspase 3 and 6 antibodies staining. Caspase 3 and 6 immunoexpressions of resveratrol and oxytocin subgroups were moderate when compared with dexamethasone subgroup. Except for the resveratrol subgroup, which had an increase in expression, the majority of subgroups were similar to SG in terms of intercellular connections (Connexin 32 and 43). Conclusion Resveratrol leads to the best outcome after facial nerve crush injury in rats when compared with dexamethasone and oxytocin, even though these agents demonstrate a significant improvement in facial nerve regeneration.