Recovery of rat muscle size but not function more than 1 year after a single botulinum toxin injection

Samuel R. Ward, Viviane B. Minamoto, Kentaro P. Suzuki, Jonah B. Hulst, Shannon N. Bremner, Richard L. Lieber*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Introduction: Neurotoxin injection is used to treat a wide variety of neuromuscular disorders. The purpose of this study was to measure the functional and structural properties of botulinum toxin–injected adult rat skeletal muscle over nearly the entire lifespan. Methods: Ten groups of animals were subjected to either neurotoxin injection [Botox, Type A (BT-A); Allergan, Irvine, California] or saline solution injection. Neurotoxin-injected animals (n = 90) were analyzed at different time-points: 1 week; 1 month; 3 months; 6 months; 12 months; or 18 months. Results: In spite of the recovery of structural features, such as muscle mass and fiber area, dorsiflexion torque production remained significantly depressed by 25%, even at 12 months after neurotoxin injection. Discussion: The data demonstrate that, after a single BT-A injection, although gross muscle morphology recovered over a 12-month time period, loss of contractile function did not recover. Muscle Nerve 57: 435–441, 2018.

Original languageEnglish (US)
Pages (from-to)435-441
Number of pages7
JournalMuscle and Nerve
Issue number3
StatePublished - Mar 2018


  • Botox
  • aging
  • denervation neurotoxin
  • muscle fiber type
  • muscle physiology
  • neuromuscular junction

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)


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