Comparison of effects of anatoxin-a(s) and paraoxon, physostigmine and pyridostigmine on mouse brain cholinesterase activity.

Anatoxin-a(s), an alkaloid neurotoxin from the freshwater cyanobacterium, Anabaena flos-aquae NRC-525-17, was compared to paraoxon, physostigmine and pyridostigmine for effects on brain cholinesterase after i.p. injection into Balb/c mice. The duration of clinical signs in mice injected with anatoxin-a(s) persisted longer than in mice given the carbamates and was comparable with that of paraoxon. Anatoxin-a(s) did not inhibit brain cholinesterase activity suggesting that this toxin is unable to cross the blood-brain barrier.