Muscle Fiber-Type Changes Induced by Botulinum Toxin Injection in the Rat Larynx

Abstract

This study examined muscle fiber-type alterations after single or multiple botulinum toxin (BT) injections to better understand possible morphologic changes induced by therapeutic BT injections in patients with spasmodic dysphonia. Muscle fiber staining was accomplished in rat intrinsic laryngeal muscles with antibodies to specific myosin heavy chains. Results indicated that the typical baseline distributions of type II muscle fibers (ie, types IIa, IIb, IIx, and IIL) were altered by BT injection, while no change was observed in type I fibers. Embryonic fibers were observed only along the needle insertion site at 7 days post BT injection. Although inferences from these animal data to human neuromuscular function must be made with caution, our findings provide insight into the possible cellular and molecular changes characterizing BT-injected muscles.

Get full access to this article

View all access options for this article.

References

Coffield

Considine

Simpson

. The site and mechanism of action of botulinum toxin. In: Jankovic

Hallett

, editors. Therapy with botulinum toxin. New York: Marcel Dekker; 1994. p. 3–13.

Grow

Kendall-Wassmuth

Grober

et al. Muscle fiber type correlates with innervation topography in the rat serratus anterior muscle. Muscle Nerve 1996;19:605–13.

Soha

Callaway

Van Essen

. Lack of fiber type selectivity during reinnervation of neonatal rabbit soleus muscle. Dev Biol 1989;131:401–14.

Sullivan

Powers

Criswell

et al. Myosin heavy chain composition in young and old rat skeletal muscle: Effects of endurance exercise. J Appl Physiol 1995;78:2115–20.

Merati

Bodine

Bennett

et al. Identification of novel myosin heavy chain gene expressed in the rat larynx. Biochim Biophys Acta 1996;1306:153–9.

Horn

AKE

Porter

Evinger

. Botulinum toxin paralysis of the orbicularis oculi muscle. Type and time course of alterations in muscle structure, physiology and lid kinematics. Exp Brain Res 1993;96:39–53.

Költgen

Ceballos-Baumann

Franke

. Botulinum toxin converts muscle acetylcholine receptors from adult to embryonic. Muscle Nerve 1994;17:779–84.

Brown

Holland

Ironton

. Nodal and terminal sprouting from motor nerves in fast and slow muscles of the mouse. J Physiol (Lond) 1980;306:493–510.

Brown

Holland

Hopkins

. Motor nerve sprouting. Annu Rev Neurosci 1981;4:17–42.

10.

Inagi

Connor

Ford

et al. Physiologic assessment of botulinum toxin effects in the rat larynx. Laryngoscope 1998;108:1048–54.

11.

Inagi

Schultz

Ford

. An anatomical study of the rat larynx: Establishing the rat model for neuromuscular function. Otolaryngol Head Neck Surg 1998;118:74–81.

12.

SAS/STAT user's guide. Version 6. 4th ed. Vol 2. Cary (NC): SAS Institute; 1989.

13.

Ermini

Ford

Schultz

. The rat as an animal model for assessing the results of botulinum toxin on laryngeal muscle. Abstracts of the 18th Meeting of the Association for Research in Otolaryngology, St Petersburg Beach (FL), Feb 5–9, 1995. p. 20.

14.

Merati

Turner

WJD

Dang

et al. Fiber type size and composition of rat thyroarytenoid muscle in the normal and denervated state. Otolaryngol Head and Neck Surg 1995;113:118–9.