Accordingly, functional interrelationships related to mesocortical and mesolimbic pathways of A2A/D2 receptor interactions that are impaired by ethanol administrations may result in emotional, motivational, rewarding, and addiction behavior disruption and learning dysfunction, which reinforces the putative role of the adenosine modulation system in several neuropathologies, such as anxiety, drug addiction, schizophrenia, and depression [71,122]. This evidence concerns the gene IGKV2D-29 and major depressive disorder.