Chemical neuroanatomy of the vesicular amine transporters

Acetylcholine, catecholamines, serotonin, and histamine are classical neuro transmitters, These small molecules also play important roles in the endocr ine and immune/inflammatory systems, Serotonin secreted from enterochromaff in cells of the gut epithelium regulates gut motility; histamine secreted f rom basophils and mast cells is a major regulator of vascular permeability and skin inflammatory responses; epinephrine is a classical hormone release d from the adrenal medulla, Each of these molecules is released from neural , endocrine, or immune/inflammatory cells only in response to specific phys iological stimuli. Regulated secretion is possible because amines are store d in secretory vesicles and released via a stimulus-dependent exocytotic ev ent. Amine storage-at concentrations orders of magnitude higher than in the cytoplasm-is accomplished in turn by specific secretory vesicle transporte rs that recognize the amines and move them from the cytosol into the vesicl e. Immunohistochemical visualization of specific vesicular amine transporte rs (VATs) in neuronal, endocrine, and inflammatory cells provides important new information about how amine-handling cell phenotypes arise during deve lopment and how vesicular transport is regulated during homeostatic respons e events, Comparison of the chemical neuroanatomy of VATs and amine biosynt hetic enzymes has also revealed cell groups that express vesicular transpor ters but not enzymes for monoamine synthesis, and vice versa: their functio n and regulation is a new topic of investigation in mammalian neurobiology, The chemical neuroanatomy of the vesicular amine transporters is reviewed here. These and similar data emerging from the study of the localization of the recently characterized vesicular inhibitory and excitatory amino acid transporters will contribute to understanding chemically coded synaptic cir cuitry in the brain, and amine-handling neuroendocrine and immune/inflammat ory cell regulation.