Table 1.

Naturally occurring agonists and antagonists of different nicotinic acetylcholine receptors (nAChRs).

Compound	Source	Activity
acetylcholine	-	Prototypic agonist at all nicotinic receptors
choline	-	Agonist at α7 and muscle nAChRs
nicotine	Tobacco plant	Agonist at most nAChR subtypes; antagonist at α9 nAChR
epibatidine	Epipedobates frogs	Agonist at most nAChR subtypes; antagonist at α9 nAChR
cytisine	Plants of Fabaceae family	Partial agonist at neuronal nAChRs
anatoxin-a	Cyanobacteria	Non-selective agonist of nAChRs
anabaseine	Certain species of ants and marine worms	Agonist at neuronal nAChRs
d-tubocurarine	Chondodendron tomentosum plant	Non-selective antagonist
coniine	Conium maculatum plant	Antagonist at muscle nAChRs
pinnatoxins, 1,3 desmethyl spirolide, gymnodimines	dinoflagellates	Non-selective antagonists
pictamine	Clavelina picta ascidian	Antagonist at neuronal nAChRs