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Joined 2026-09-21 Message
Incoming links: Nicotine in ChEBI
Nicotine 2026-11-05
Nicotine is an alkaloid whose structure combines a pyridine ring with a substituted pyrrolidine ring. Its neutral molecular formula is . The naturally occurring form specified by ChEBI has S stereochemistry, so connectivity and atom count alone do not state the complete identity.[ref]
Nicotine acts as an agonist at nicotinic acetylcholine receptors. It is a ligand acting on a receptor, not the receptor itself and not acetylcholine. Different receptor subunit combinations and the surrounding circuit can change the observed response.
A 2011 study tested this circuit dependence using loss of the α5 receptor subunit and targeted restoration in the medial habenula. The work connected the subunit to a signal limiting nicotine intake in the tested animals.[ref]
Habenular α5 nicotinic receptor subunit signalling controls nicotine intake by Christie D. Fowler and others. Abstract; subunit loss, habenular rescue and intake-related inhibitory signalling
Changing a receptor component while leaving the chemical ligand identifiable helps distinguish molecular identity from biological sensitivity. It does not reduce every action of nicotine to that one circuit.