Nicotinic acetylcholine receptors and nicotine addiction

Nicotine is an addictive chemical compound and the main psychoactive ingredient in tobacco. It acts on nicotinic acetylcholine receptors (nAChRs) in the mesolimbic reward pathway of the brain. Neurones of this pathway release dopamine, which helps establish nicotine addiction over time. Nicotine also activates the habenulo-interpeduncular pathway, which suppresses the centres responsible for withdrawal symptom development. Different types of nAChRs, which vary in their sensitivity to nicotine and ability to desensitise, are present in these pathways. This allows nAChRs to adapt to prolonged nicotine exposure in a way that discourages quitting. Various pharmaceutical, biotechnological and legislative efforts are being made to overcome the addiction associated adaptations in the brain.