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Subcellular localization of synaptophysin in noradrenergic nerve terminals: A biochemical and morphological study
Author(s) -
Annaert Wim G.,
Llona Isabel,
De Ridder Erik,
Weyns Andre,
Quatacker Jos,
De Potter Werner P.
Publication year - 1995
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.890210110
Subject(s) - synaptophysin , vesicle , synaptic vesicle , chromogranin a , vas deferens , biology , chemistry , medicine , endocrinology , biophysics , biochemistry , membrane , immunohistochemistry , immunology
The subcellular localization of synaptophysin was investigated in noradrenergic nerve terminals of bovine vas deferens and dog spleen and compared with membrane‐bound and soluble markers of noradrenergic storage vesicles. At the light microscopical level chromogranin A‐ and cytochrome b 561 ‐ immunoreactivity revealed an identical and very dense innervation of the entire vas deferens. In the case of synaptophysin, most immunoreactivity was found only in the outmost varicosities closest to the lumen, which were also positive for chromogranin A. Small dense‐core vesicles of dog spleen were purified using a combination of velocity gradient centrifugation and size exclusion chromatography. Small dense‐core vesicles were enriched 64 times as measured by the noradrenaline content. Enrichments for dopamine‐β‐hydroxylase were in a similar range. Synaptophysin‐containing vesicles were smaller in size and they did not contain the typical noradrenergic markers dopamine‐β‐hydroxylase, cytochrome b 561 , and noradrenaline. Instead, they might store adenosine triphosphate (ATP). A greater part of synaptophysin immunoreactivity was consistently found at high sucrose densities at the position of large dense‐core vesicles. © 1995 Wiley‐Liss, Inc. We conclude that in the noradrenergic nerve terminal: (1) small dense‐core vesicles have a membrane composition similar to large dense‐core vesicles, indicating that the former are derived from the latter; and (2) synaptophysin seems not to be present on small dense‐core vesicles. We suggest the possibility that synaptophysin‐containing vesicles form a residual population whose role in neurotransmission has been taken over by large and small densecore vesicles following noradrenergic differentiation.