Proteomic changes in rat thyroarytenoid muscle induced by botulinum neurotoxin injection

Botulinum neurotoxin (BoNT) injection into the thyroarytenoid (TA) muscle is a commonly performed medical intervention for adductor spasmodic dysphonia. The mechanism of action of BoNT at the neuromuscular junction is well understood, however, aside from reports focused on myosin heavy chain isoform abundance, there is a paucity of data addressing the effects of therapeutic BoNT injection on the TA muscle proteome. In this study, 12 adult Sprague Dawley rats underwent unilateral TA muscle BoNT serotype A injection followed by tissue harvest at 72 h, 7 days, 14 days, and 56 days postinjection. Three additional rats were reserved as controls. Proteomic analysis was performed using 2-D SDS-PAGE followed by MALDI-MS. Vocal fold movement was significantly reduced by 72 h, with complete return of function by 56 days. Twenty-five protein spots demonstrated significant protein abundance changes following BoNT injection, and were associated with alterations in energy metabolism, muscle contractile function, cellular stress response, transcription, translation, and cell proliferation. A number of protein abundance changes persisted beyond the return of gross physiologic TA function. These findings represent the first report of BoNT-induced changes in any skeletal muscle proteome, and reinforce the utility of applying proteomic tools to the study of system-wide biological processes in normal and perturbed TA muscle function.