Serotonin (5‑hydroxytryptamine, 5‑HT) is a remarkably versatile neurotransmitter—produced from dietary tryptophan—that governs mood, sleep, appetite, cognition and even cardiovascular tone. The serotonin pathway (or serotonin signaling pathway) encompasses every step from tryptophan’s conversion by TPH and AADC, to vesicular packaging, calcium‑triggered release, receptor binding across 14+ 5‑HT subtypes, and termination via SERT reuptake and MAO‑A […]