ABSTRACT

Dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) are both important neurotransmitters in the human brain. A schematic drawing of a neurotransmitter synapse representative for both DA and serotonin is shown in Figure 11.1. Neurotransmitters are released from vesicles into the synaptic cleft where they subsequently can activate a number of postsynaptic receptors (PR). The neurotransmitters may also activate a number of autoreceptors (AR) which regulate the synthesis and release of the transmitters, and generally, activation of autoreceptors leads to inhibition of neurotransmitter synthesis and release. The autoreceptors can be localized both presynaptically or somatodendritically (on the cell bodies). The concentration of neurotransmitter in the synapse may also be regulated by active reuptake into the presynaptic terminal by transporters (T).