Abstract
Expanding knowledge about the cellular composition of subcortical brain regions demonstrates large heterogeneity and differences from the cortical architecture. Recently, we described three subtypes of somatostatin-expressing (Sst) neurons in the mouse ventral tegmental area (VTA) and showed their local inhibitory action on the neighbouring dopaminergic neurons (Nagaeva et al., 2020). Here, we report that VTA Sst neurons also project far outside the VTA and innervate several forebrain regions that are mainly involved in the regulation of emotional behaviour. When we deleted these VTA Sst neurons several behaviours and drug effects were affected, such as home cage activity, sensitization of locomotor activity to morphine, fear conditioning responses, and reactions to inescapable stress of forced swimming, often in a sex-dependent manner. Interestingly, the majority of these Sst projecting neurons was found to express Vglut2 and Th, but not Dat. Together, these data demonstrate that VTA Sst neurons have their selective projection targets, which are distinct from the main targets of VTA dopamine neurons and involved in the regulation of a variety of behaviours mostly associated with the stress response. This, in turn, makes these VTA neurons a meaningful addition to the somatostatinergic system of the brain.
Competing Interest Statement
The authors have declared no competing interest.
