title: Acrylamide inhibits nerve sprouting induced by botulinum toxin type A.
abstract: Botulinum toxin type A is a potent muscle relaxant that blocks the transmission and release of acetylcholine at the neuromuscular junction. Intramuscular injection of botulinum toxin type A has served as an effective and safe therapy for strabismus and focal dystonia. However, muscular weakness is temporary and after 3-4 months, muscle strength usually recovers because functional recovery is mediated by nerve sprouting and reconstruction of the neuromuscular junction. Acrylamide may produce neurotoxic substances that cause retrograde necrotizing neuropathy and inhibit nerve sprouting caused by botulinum toxin type A. This study investigated whether acrylamide inhibits nerve sprouting after intramuscular injection of botulinum toxin type A. A tibial nerve sprouting model was established through local injection of botulinum toxin type A into the right gastrocnemius muscle of Sprague-Dawley rats. Following intramuscular injection, rats were given intraperitoneal injection of 3% acrylamide every 3 days for 21 days. Nerve sprouting appeared 2 weeks after intramuscular injection of botulinum toxin type A and single-fiber electromyography revealed abnormal conduction at the neuromuscular junction 1 week after intramuscular injection of botulinum toxin type A. Following intraperitoneal injection of acrylamide, the peak muscle fiber density decreased. Electromyography jitter value were restored to normal levels 6 weeks after injection. This indicates that the maximal decrease in fiber density and the time at which functional conduction of neuromuscular junction was restored were delayed. Additionally, the increase in tibial nerve fibers was reduced. Acrylamide inhibits nerve sprouting caused by botulinum toxin type A and may be used to prolong the clinical dosage of botulinum toxin type A.
authors.affiliation: Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Second Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xiang
authors.affiliation: Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China.
authors.forename: Xingyue
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Neurology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang Province, China.
authors.forename: Huaying
authors.initials: H
authors.lastname: Cai
keywords: acrylamide; action potential mean consecutive difference; botulinum toxin type A; dysmyotonia; electromyography; fiber density; nerve fibers; nerve regeneration; nerve sprouting; neural regeneration; neuromuscular junction; peripheral nerve regeneration; single-fiber EMG