Neurotoxin

Neurotoxins are substances that disrupt the structure or function of the nervous system, damaging neurons or interfering with neural signaling. They can be natural or synthetic and vary in potency and target, from ion channels and synaptic vesicles to receptors and mitochondrial pathways. Some act on peripheral nerves or muscle junctions, others affect the central nervous system.

Mechanisms include inhibition or stimulation of neurotransmitter release, blockade or modulation of ion channels (such as sodium, potassium, and calcium channels), interference with receptor function, or impairment of cellular energy production. Notable effects include flaccid paralysis from impaired acetylcholine release, or spastic paralysis from loss of inhibitory neurotransmission.

Prominent examples encompass botulinum neurotoxin, produced by Clostridium botulinum, which cleaves SNARE proteins and blocks acetylcholine release at neuromuscular junctions; tetanus neurotoxin, from Clostridium tetani, which disrupts inhibitory neurotransmission in the spinal cord; tetrodotoxin and saxitoxin, which block voltage-gated sodium channels; conotoxins, a diverse group of peptide toxins from cone snails with varied targets on ion channels and receptors; domoic acid, a marine toxin that overactivates glutamate receptors; and plant-derived alkaloids such as curare alkaloids that block nicotinic acetylcholine receptors, as well as organophosphates like sarin that inhibit acetylcholinesterase.

Safety and medical relevance: exposure requires prompt medical evaluation and supportive care; specific antitoxins are available for some agents, and decontamination may be indicated. Some neurotoxins have legitimate clinical uses in controlled doses, with botulinum toxin being the most widely known example in medicine and aesthetics.