Fig. 2

Amphetamine and its related signalling pathway: Positive ions (Ca²⁺ and Na⁺) can pass through the membrane when these receptors are activated. Released DA binds to the D1R receptor at the same time. Depolarization occurs as a result of positive ion flux, resulting in an increase in Ca²⁺ concentration. When activated D1R binds to Gs, it causes adenyl cyclase, an enzyme that converts ATP to cAMP, to become activated, which activates the PKA signalling pathway. The cAMP binds to the CREB protein, which regulates gene expression and thereby induces the expression of PDYN, arc and c-fos genes, which are responsible for the induction and maintenance of addiction