Expression of Toll-Like Receptor Messenger Ribonucleic Acid in the Distal Facial Nerve after Facial Nerve Injury

Background and Objectives This study aimed to evaluate whether Toll-like receptors (TLRs) messenger ribonucleic acid (mRNA) were expressed in the facial nerve after incurring a crush or an injury of the facial nerve. Materials and Method An adult Sprague-Dawley underwent a crush or injury of the unilateral facial nerve. The crush or injury was incurred by a cutting at the midpoint between the facial nerve trunk and its branch. The whisker movement of vibrissae muscle was examined 4 and 14 days after injury. Real-time polymerase chain reaction was performed for the normal facial nerve taken from the left side and the damaged nerve taken from the right side. Results On the 4th day of injury, the expression of TLR 9, 13 mRNA was significantly lower in the crush and injured groups than in the control group (p<0.05). On the 14th day of injury, the expression of TLR 2 mRNA was significantly higher in the injured group than in the control group (p<0.05). Conclusion The expressions of TLR 9, 13 mRNA in the distal facial nerve after injury in the crush and injured groups were significantly lower than that in the control group, but the expression of TLR 2 mRNA in the injured group was significantly higher. Therefore, TLRs may be involved in facial nerve damage and regeneration.