HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chad, D. Articles by Reichlin, S. Search for Related Content PubMed PubMed Citation Articles by Chad, D. Articles by Reichlin, S.

Unmyelinated axon subpopulations in the rat peripheral nervous system

Departments of Neurology (Drs. Chad, Rasool, and Bradley and Mr. Good) and Medicine (Dr. Reichlin) of the Tufts-New England Medical Center, Boston, MA.

using the neurotoxin capsaicin, we examined subpopulations of unmyelinated axons in mixed (sciatic), cutaneous (sural), and muscular (nerve to soleus) nerves. Administration of capsaicin to neonatal rats caused reduction of the sciatic nerve immunoreactive (IR)-substance P (by 45%) and IR-somatostatin (by 84%) contents. This correlated with a substantial reduction in unmyelinated axons in the sciatic and sural nerves (45% and 65%, respectively), although there was no significant decrease in unmyelinated axons in the nerve to soleus. In a parallel study, we have shown that sympathetic ganglia-derived unmyelinated axons account for about 20 to 25% of the total unmyelinated axon population in both the sural nerve and the nerve to soleus. Thus, in the sural nerve, the majority of unmyelinated axons are dorsal root ganglia-derived, contain either substance P or somatostatin, and are capsaicin-sensitive; whereas in the nerve to soleus, the majority of unmyelinated axons are dorsal root ganglia-derived but are insensitive to capsaicin and do not contain substance P or somatostatin. These latter unmyelinated axons presumably contain a yet to be defined neurotransmitter and may be the axons connecting with muscular ergoreceptors, a subpopulation of unmyelinated axons that are biochemically and functionally distinct from the unmyelinated axons of cutaneous nerves.

Address correspondence and reprint requests to Dr. Chad, Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01605.

This work was supported in part by a grant from the MDA. Dr. Chad was a Research Fellow of the MDA.

Portions of this paper were presented at the thirty-fourth annual meeting of the American Academy of Neurology, Washington, DC, April 1982.

Accepted for publication November 1, 1982.

This article has been cited by other articles:

				Final Report on the Safety Assessment of Capsicum Annuum Extract, Capsicum Annuum Fruit Extract, Capsicum Annuum Resin, Capsicum Annuum Fruit Powder, Capsicum Frutescens Fruit, Capsicum Frutescens Fruit Extract, Capsicum Frutescens Resin, and Capsaicin International Journal of Toxicology, January 1, 2007; 26(1_suppl): 3 - 106. [Abstract] [Full Text] [PDF]