Toxins cholinergic poisoning

Botulism is most commonly caused by ingestion of a neurotoxin produced by Clostridium botulinum in improperly canned food. Poisoning may also occur after wound contamination with the organism. Infant botulism may occur when spores of the organism germinate and manufacture the toxin in the intestinal tract of infants. Botulinum toxin works by inhibiting ACh release at all cholinergic synapses. 

A similar plant is water hemlock, which contains a different toxin, called cicutoxin. This is very potent and exposure to it is often fatal. One study of poisonings with this plant found that 30 per cent of victims died. It affects primarily the brain and the spinal cord, causing seizures and epileptic fits, possibly by overstimulating certain nerves (cholinergic pathways). 

Food-borne botulism results from the ingestion of food contaminated with preformed toxins or toxin-producing spores from C. bo-tulinum. C. botulinum poisoning is relatively rare only 110 cases are reported per year in the United States. Botulism is almost always associated with improper preparation or storage of food. Seven distinct toxins (A to G) have been described. The toxins, which are produced by the bacteria and released on lysis, are the most potent biologic or chemical toxins known to humans. The toxin prevents the release of acetylcholine at the peripheral cholinergic nerve terminal. Toxin activity has prompted the use of minute locally injected doses to treat select spastic disorders, such as blepharospasm, hemifacial spasm, and certain dystonias. ... 

They bind initially to ganglioside in the neuromuscular jimction, one subunit then being internalized as with the diphtheria toxin (Box 29-A). Botulinum toxins specifically enter motor neurons, while tetanus toxin is taken up via synaptic vesicle endocytosis by both peripheral and central neurons. Retrograde axonal transport carries the toxin into the central nervous system and across synaptic clefts into cholinergic intemeurons, which are poisoned. 

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