GPR139 and schizophrenia: Another GPR139 agonist 4-oxo-3,4-dihydro-1,2,3-benzotriazine has been reported to improve social withdrawal in a preclinical model of the negative symptom of schizophrenia (Atienza et al., 2018), involving the mesocortical pathway (initiate from VTA but instead project to the prefrontal cortex) (Ekhtiari and Paulus, 2016).