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Morphological evidence for functional capsaicin receptor expression and calcitonin gene-related peptide exocytosis in isolated peripheral nerve axons of the mouse.
- Source :
-
Neuroscience [Neuroscience] 2004; Vol. 126 (3), pp. 585-90. - Publication Year :
- 2004
-
Abstract
- Rat sciatic nerve axons express capsaicin, proton and heat sensitivity and respond to stimulation with a Ca2+-dependent and graded calcitonin gene-related peptide (CGRP) release. In this study we demonstrate that similar functions, including capsaicin-induced CGRP release, are to be found in the desheathed sciatic nerve of the mouse. We have morphologically investigated the mechanisms of this axonal release in regions away from the active zones of synapses. Capsaicin receptor 1 (TRPV1) and CGRP immunostaining was performed using electron microscopic visualization. TRPV1 was identified in the axoplasm and inside vesicles--presumably on axonal transport--as well as in considerable quantity in the axonal plasma membrane of unmyelinated nerve fibers. Most of the unmyelinated axons were immunopositive for CGRP and in unstimulated nerves CGRP-containing vesicles almost entirely filled the axoplasm. After capsaicin stimulation (10(-6) M for 5 min), the fibers appeared depleted of CGRP with only few vesicles remaining as well as some residual staining of the axoplasm. In addition a large number of vesicles were fused with the axonal membrane, forming classical exocytotic figures--the omega structures--lined with CGRP immunoreactive product. These results present morphological evidence for the distribution of TRPV1 along unmyelinated axons in peripheral nerve and also provide the first demonstration of vesicular neuropeptide exocytosis along unmyelinated axons in peripheral nerve.
- Subjects :
- Animals
Axons drug effects
Axons ultrastructure
Calcitonin Gene-Related Peptide drug effects
Capsaicin pharmacology
Cytoplasmic Vesicles drug effects
Cytoplasmic Vesicles metabolism
Cytoplasmic Vesicles ultrastructure
Exocytosis drug effects
Female
Male
Mice
Microscopy, Electron
Rats
Receptors, Drug drug effects
Sciatic Nerve drug effects
Sciatic Nerve ultrastructure
Axons metabolism
Calcitonin Gene-Related Peptide metabolism
Exocytosis physiology
Receptors, Drug biosynthesis
Sciatic Nerve metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0306-4522
- Volume :
- 126
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 15183508
- Full Text :
- https://doi.org/10.1016/j.neuroscience.2004.03.017