[The mechanism of the development of drug dependence]

Drug dependence, the physical and psychological one after chronic drug administration, is a serious clinical and social problem. The mechanism of development of drug dependence is mainly related to the modification of dopaminergic system. In addition, recent reports demonstrate that the other neuronal systems including noradorenergic, glutamatergic, serotonergic, histaminergic and orexinergic neurons could regulate the activity of dopaminergic neurons that results in the development of drug addiction after chronic drug administration. In the cellular and molecular levels, the up-regulation of some key signaling molecules such as cAMP and PKA or peptides such as NPY and dynorphin may be involved in the mechanisms. In this review, we outline the recent knowledge about the mechanism of development of drug addiction.