https://www.ncbi.nlm...cles/PMC5171775
Although the co-release of GABA or glutamate with dopamine is more common than originally suspected, significant populations of VTA neurons are devoid of dopamine markers but express markers indicative of GABA or glutamate release. <...> We found also that a subset of VGLUT2+ VTA neurons projecting to the ventral pallidum (VP) or lateral habenula (LHb) co-release glutamate and GABA. However, in the absence of other inputs and congruent with the behavioural reinforcement induced by short stimulus trains, train activation of VGLUT2+ VTA inputs to VP were net excitatory, but net inhibitory in the LHb.