Coupled to second messenger pathways controlling ion channels via G-proteins
Two Structural Categories of NTs
1) Small molecules containing nitrogen - catecholamines (dopamine, norepi, epi), serotonin, GABA, glutamate, acetylcholine, histamine, NO
2) Neuropeptides - endophins (bind to opioid receptors), GH, TSH
Synthesized from a common pathway beginning with L-tyrosine which is supplied in the diet or synthesized in the liver from phenylalanine via phenylalanine hydroxylase
L-tyrosine goes through a hydroxylation via tyrosine hydroxylase and cofactor tetrahydrobiopterin to become dihydroxyphenylalanine (DOPA). Decarboxylation then occurs via DOPA decarboxylase and the cofactor pyridoxal phosphate to create Dopamine. Another hydroylation occurs via dopamine-beta-hydroxylase (DBH) with cofactors Copper and Vit C to become Norepi. Phenylethanol-amine N-methyl-transferase uses methylation to create Epi from Norepi.