Figure 1.

Norepinephrine is synthesized from dopamine by dopamine β-hydroxylase in neurons of the locus coeruleus. Before the final β-oxidation, norepinephrine is transported into synaptic vesicles by a vesicual monoamine transporter. The vesicles are then transported along the axons comprising the noradrenergic bundle to release sites. At the synapse norepinephrine is released into the synaptic cleft where it binds to various pre- and post-synaptic adrenergic receptors which subsequently activate distinct G protein coupled signal cascades.