When a drug blocks reuptake or breakdown of a neurotransmitter by the action of enzymes, the drug is acting as an neurons.
Within a neuron, precursor are substances that are converted into neurotransmitters by synthetic enzymes. The neurotransmitters are then packed into vesicules for transport to the synapse and release there. Neurotransmitters are released into the synapse when calcium ions trigger opening of the docked vesicule.
The neurotransmitters then cross the synaptic gap and bind with postsynaptic receptors, which are activated to open ion channels with the result that the post-synaptic neuron is either fired or inhibited.
Further release of neurotransmitters is inhibited by autoreceptors, which tell the presynaptic terminal button to stop releasing neurotransmitters. Reuptake absorbs remaining neurotransmitters in the synapse back into the terminal button. Another termination method is enzymatic deactivation.
