ABSTRACT
All psychoactive drugs work on some part of the synapse. It is important to note at the outset that drugs are not classified according to where they act. Drugs like p-chlorophenylalanine affect the synthesis of 5HT by blocking the enzymatic reaction that converts tryptophan into 5-hydroxy-trypto-phan. Another presynaptic effect can be on the storage of the neurotransmitter. The classic example here is reserpine. This drug depletes catecholamine neurons of their neurotransmitter. The final stage of presynaptic action is release from the terminal bouton. For example, dopamine release can be blocked by gamma-hydroxybutyrate (GHB). GHB acts particularly on the dopamine cells of the basal ganglia. It is becoming popular at 'raves' but has been labeled as a date-rape drug. Drugs can also block reuptake of the neurotransmitter, and the group of antidepressants called the tricyclics work in this way. These drugs include desipramine, which blocks the reuptake of norepinephrine, and imipramine and amitryptyline, which block the reuptake of serotonin.
