Nicotinic receptors mediate stress-nicotine detrimental interplay via dopamine cells' activity.

Epidemiological studies report strong association between mood disorders and tobacco addiction. This high comorbidity requires adequate treatment but the underlying mechanisms are unknown. We demonstrate that nicotine exposure, independent of drug withdrawal effects, increases stress sensitivity, a major risk factor in mood disorders. Nicotine and stress concur to induce long-lasting cellular adaptations within the dopamine (DA) system. This interplay is underpinned by marked remodeling of nicotinic systems, causing increased ventral tegmental area (VTA) DA neurons' activity and stress-related behaviors, such as social aversion. Blocking beta2 or alpha7 nicotinic acetylcholine receptors (nAChRs) prevents, respectively, the development and the expression of social stress-induced neuroadaptations; conversely, facilitating alpha7 nAChRs activation specifically in the VTA promotes stress-induced cellular and behavioral maladaptations. Our work unravels a complex nicotine-stress bidirectional interplay and identifies alpha7 nAChRs as a promising therapeutic target for stress-related psychiatric disorders.Molecular Psychiatry advance online publication, 25 July 2017; doi:10.1038/mp.2017.145.