Botulinum neurotoxins: mechanism of action and therapeutic applications.

Recent studies have led to the discovery of the molecular lesions in motor neurons caused by botulinum neurotoxins. These neurotoxins are metalloproteinases that enter the cytosol and very specifically cleave protein components of the neuroexocytosis apparatus. Consequently, acetylcholine cannot be released and the muscle is paralysed. For this reason, botulinum neurotoxins are increasingly being used to treat a variety of conditions where a functional paralysis of neuromuscular junctions is useful as therapy.