Nerve-muscle pedicle implantation in the denervated thyroarytenoid muscle of aged rats

Conclusion: Nerve-muscle pedicle (NMP) implantation was effective in the recovery of atrophic changes in the denervated thyroarytenoid (TA) muscle in aged rats. Objectives: To evaluate the effects of NMP implantation on the denervated TA muscle in aged rats. Methods: Wistar rats aged 20 months and 8 weeks were respectively divided into two groups in which the left recurrent laryngeal nerve (RLN) was transected without (aged/young DNV group) or with (aged/young NMP group) NMP implantation. The aged DNV and NMP groups were further divided into two subgroups, based on the period after RLN transection (10 or 20 weeks). In the DNV groups, we assessed the area of muscle and the number of neuromuscular junctions (NMJs) histologically. In the NMP groups, we performed electromyography and histological assessments. For electromyography, we stimulated the transferred nerve and evaluated the muscle action potentials (MAPs) of the TA muscle. Results: The muscle areas in the aged NMP groups were significantly larger than those in the aged DNV groups. More NMJs were found in aged NMP groups compared with aged DNV groups. MAPs were seen in all NMP animals. No significant differences were observed between the aged and young NMP groups in histological and physiological assessments.