description
Nicotine is one of the main psychoactive ingredients in tobacco that contributes to the harmful tobacco smoking habit. A common feature of addictive drugs, including nicotine, is that they increase dopamine (DA) release in the nucleus accumbens (NAc). The principal dopaminergic projections to NAc arise from neurons in the ventral tegmental area (VTA). In the VTA, alpha6- and alpha4beta2-containing nAChRs (alpha6*-AChRs and alpha4beta2*-AChRs, respectively) are located on GABAergic terminals and provide inhibitory inputs onto DAergic neuons, while alpha7*-nAChRs are located on glutamatergic terminals and activation of these receptors enhances glutamate release and increases excitability of DAergic neurons. Nicotine acts as an agonist to activate and desensitize these nicotinic acetylcholine receptors (nAChRs). After a short exposure to nicotine, alpha6*- and alpha4beta2*- nAChRs on GABAergic afferents are desensitized, decreasing GABA release and decreasing local inhibition of DA neurons. But the alpha7*-nAChRs on glutamatergic afferents remain active and enhance glutamate excitation of the DA neurons, leading to increased DA release in the NAc -and so facilitate the reinforcing effects of nicotine

external resources
NCBI:583255
KEGG:hsa05033
PUBMED:19498417
PUBMED:15661626
PUBMED:12436424
PUBMED:19669944
PUBMED:19434058
PUBMED:19184650
PUBMED:15165747
PUBMED:12716925
PUBMED:18723034
PUBMED:18640919
PUBMED:11906697
PUBMED:14708004
PUBMED:17009926
PUBMED:14747518
PUBMED:20485364
PUBMED:16251989
PUBMED:20833261

genes
CACNA1A , CACNA1B , CHRNA4 , CHRNA7 , CHRNB2 , GABRA1 , GABRA2 , GABRA3 , GABRA4 , GABRA5 , GABRA6 , GABRB1 , GABRB2 , GABRB3 , GABRD , GABRE , GABRG1 , GABRG2 , GABRG3 , GABRP , GABRR1 , GABRR2 , GRIA1 , GRIA2 , GRIA3 , GRIA4 , GRIN1 , GRIN2A , GRIN2B , GRIN2C , GRIN2D , CHRNA6 , GABRQ , SLC17A7 , SLC17A6 , GRIN3A , GRIN3B , SLC32A1 , GABRR3 , SLC17A8 ,