DRD2 and major depressive disorder: Such a notion is justified when considering an interesting hypothesis, which can explain this phenomenon, that suggests that the anhedonia observed in patients with depression is related to a decrease in the sensitivity of postsynaptic D2 dopamine receptors (D2R) in the nucleus accumbens that are responsible for the reward function, as well as those connecting the therapeutic effects of long-term antidepressant administration with the increase in sensitivity of D2R in these brain areas [16].