Uptake and axonal transport of horseradish peroxidase isoenzymes by different neuronal types

Key B. and Giorgi P.P. (1987) Uptake and axonal transport of horseradish peroxidase isoenzymes by different neuronal types. Neuroscience, 22 3: 1135-1144. doi:10.1016/0306-4522(87)92988-5


Author Key B.
Giorgi P.P.
Title Uptake and axonal transport of horseradish peroxidase isoenzymes by different neuronal types
Journal name Neuroscience   Check publisher's open access policy
ISSN 0306-4522
Publication date 1987-01-01
Sub-type Article (original research)
DOI 10.1016/0306-4522(87)92988-5
Volume 22
Issue 3
Start page 1135
End page 1144
Total pages 10
Subject 2800 Neuroscience
Abstract The uptake and transport of basic and acidic horseradish peroxidase isoenzymes was compared in the neuromuscular, visual and olfatory systems of Xenopus larvae and postmetamorphic frogs. The concentration (w/v) of the two preparations was corrected to compensate for their difference in enzymatic activity (unit/w), which was seven-fold higher in basic horseradish peroxidase. Uptake and transport of horseradish peroxidase isoenzymes could be demonstrated with 7% basic horseradish peroxidase, but not with equal amounts of 49% acidic horseradish peroxidase in all systems investigated: retrograde transport from terminals of retinal ganglion cells, isthmotectal neurons and spinal motoneurons, as well as anterograde transganglionic transport along olfactory neurons. A very weak labelling of the same neuronal pathways by acidic horseradish peroxidase was obtained only after increasing the amount injected by approximately two-fold. Basic horseradish peroxidase isoenzymes were also preferentially taken up and transported retrogradely by broken axons of the optic nerve. When tested, similar results were obtained in both larvae and frogs suggesting that preferential uptake and transport of basic horseradish peroxidase is a general feature of all neurons and of all developmental stages. Electron microscopical analysis of the outer layers of the optic tectum revealed that, in the same experimental conditions producing no retrotrade labelling of optic axons, acidic horseradish peroxidase was rarely found to enter nerve terminals. It appears that interactions between horseradish peroxidase and neuronal membranes occur during uptake and transport and that molecular charge plays an important role, beyond non-specific fluid-phase endocytosis. We suggest that differences between horseradish peroxidase isoenzymes as neuronal tracers reflect a process of adsorptive endocytosis related to general characteristics of neuronal membranes (regardless of age) and not to specific receptor-mediated interactions characteristic of neuronal specificity.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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