Increased Expression of Toll-like Receptor 2 mRNA after Facial Nerve Injury in Rat

Abstract

Abstract Objectives: The aim of this study was to determine whether TLRs mRNA is expressed in the distal facial nerve after facial nerve injury. Methods: The adult male Sprague-Dawley with a body weight of 200–250g underwent injury of unilateral facial nerve. Crush or cutting injury was given at the midpoint between the facial nerve trunk and the facial nerve branch. The whisker movement of vibrissae muscle was examined 4 and 14 days after facial nerve injury. The normal facial nerve on the left side and the damaged facial nerve on the right side were taken under the inhalation anesthesia and real-time polymerase chain reaction was performed. Results: In the whisker movement of vibrissae muscle, the crush group and the cutting group showed worse scores on the 14th day than the 4th scores in each group (p<0.05). On the 4th day of injury, the expression of TLR 7 mRNA was highest in the crush group, and on the 14th day of injury, the expression of TLR 7 mRNA was highest in the cutting group. On the 14th day of injury, the expression of TLR 2 mRNA was significantly higher in the cutting group than in the control group (p<0.05), on the 4th day of injury, the expression of TLR 9, 13 mRNA was significantly lower in the crush and cutting groups than in the control group (p<0.05). Conclusions: The expression of TLR 2 mRNA in the distal facial nerve after facial nerve injury in the cutting group was significantly higher than that in the control group, but the expressions of TLR 9 and 13 mRNA in the crush and cutting groups were significantly low. Therefore, TLR mRNA may be involved in facial nerve damage and regeneration.