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Exocytosis of norepinephrine at axon varicosities and neuronal cell bodies in the rat brain
Author(s) -
Chiti Zohreh,
Teschemacher Anja G.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.06-7342com
Subject(s) - axon , norepinephrine , exocytosis , neuroscience , cell bodies , chemistry , biology , microbiology and biotechnology , endocrinology , dopamine , secretion , central nervous system
ABSTRACT Norepinephrine secretion from central neurons was widely assumed to occur by exocytosis, but the essential characteristics of this process remained unknown. We developed an approach to study it directly by amperometry using carbon fiber microelec‐trodes in organotypic rat brainstem slice cultures. Nor‐adrenergic neurons from areas A1 and A2 were fluorescently labeled by an adenoviral vector with no‐radrenergic‐specific promoter. Quantal events, consistent with exocytotic release of norepinephrine, were registered at noradrenergic axonal varicosities as well as at cell bodies. According to their charge integrals, events were grouped into two populations. The majority (~40 fC) were compatible with full exocytotic fusion of small clear and dense core vesicles shown in previous morphometric studies. The quantal size distribution was modulated by treatment with reserpine and amitriptyline. In addition, much larger quantal events (>1 pC) occurred at predominantly axonal release sites. The time course of signals was severalfold faster than in adrenal chromaffin cells, suggesting profound differences in the release machinery between these cell types. Tetrodotoxin eliminated the majority of events, indicating that release was partially, but not entirely, action potential driven. In conclusion, central norepi‐nephrine release has unique characteristics, distinguishing it from those of other monoaminergic cells in periphery and brain.—Chiti, Z., Teschemacher, A. G. Exocytosis of norepinephrine at axon varicosities and neuronal cell bodies in the rat brain. FASEB J. 21, 2540–2550 (2007)