BDNF is encoded by the BDNF gene, which is located on chromosome 11p14 [84], and has been associated with opioid dependence [86]. As a regulator of many cellular signaling pathways, BDNF is hypothesized to play a role in the transition from drug use to dependence, specifically the reward pathway that is apparent in addiction [82]. A study by Guillin et al [34] showed that increased concentrations of BDNF in the ventral tegmental area (VTA) induced an over-expression of the D3 receptor, creating a reward state similar to that of opioids.
