Abstract
We have reported that the pattern of the Trigemino-Facial reflex (T-F R) changes during axonal regeneration after facial nerve (MB; trunk of the temporal-zygomatico-orbital and both superior and inferior buccolabial branch) suture in the cat. The T-F R is induced only in the ipsilateral MB but never in PA (posterior auricular branch) in normal cats, but the reflex can be detected in PA as well as in MB during axonal regeneration after MB suture. The pattern of T-F R returned to normal at 3 to 4 months after suture. In the present study, we examined the relation between the pattern of T-F R and functional recovery by comparing the number of retrogradely labeled MB motoneurons and the antidromic latencies. At various postoperative days, 5% fast blue (FB) was injected into the distal part of the sutured MB and the labeled MB neurons were examined and compared with in normal animals. The labeled MB neurons were first detected at 6 days after suture, and the number increased until 85 days after suture. The number of labeled neurons returned to the normal values at 129 days (2909±140 vs. 3027 at 129 days). The antidromic latency was 1.37ms at 10 days and shortened progressively until around 4-5 months after suture. At 165 days, the latency (1.05 msec, N=4) also returned to the normal (1.0±0.2msec, N=95). The present results indicate that the pattern of T-F R returned to the normal, when the axonal regeneration and functional recovery have completed. The neural mechanisms of the appearance of aberrant T-F R in PA should be studied further. [Jpn J Physiol 54 Suppl:S155 (2004)]
