All these data allow us to suggest that the pharmacological combination of GAL(1-15)+SSRIs could be an effective augmentation therapy that not only enhances the antidepressant effects of SSRIs but also could modulate several systems altered in depressive patients as the HPA axis and several neuronal limbic circuits implicated in depression symptoms as despair and anhedonia, based in the interactions between the galaninergic and serotonergic systems. This evidence concerns the gene GAL and major depressive disorder.