Nicotine mainly shows its action through specific nicotinic acetylcholine receptors located in the brain. It stimulates presynaptic acetylcholine receptors thereby enhancing Ach release and metabolism.
The dopaminergic system is also stimulated by it and thus increasing the concentration of dopamine in nuclear accumbens. Nicotine induces GABA release by binding to excitatory nACh receptors located on presynaptic GABA neurons.
The serotonergic system may be involved in smoking behaviour because nicotine increases the brain's serotonin secretion, nicotine withdrawal decreases serotonin levels and a selective serotonin reuptake inhibitor antagonises the response to nicotine.
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