When a nerve impulse arrives at a 5-HT or noradrenaline nerve terminal the neurotransmitter is released from the synaptic vesicle into the synaptic cleft. Neurotransmitter molecules bind to their specific receptors on the post-synaptic membrane and the nerve impulse is propagated or inhibited, depending on the receptor type. 5-HT and noradrenaline molecules are then released from their receptors and taken back into the nerve terminal via either the 5-HT or noradrenaline re-uptake transporters. 5-HT and noradrenaline are degraded by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT), these enzymes are found in the nerve terminal.1,2
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