The localization and release of substance P and calcitonin gene-related peptide at nerve fibre endings in rat cutaneous nerve neuroma.
This study uses radiological and immunocytochemical techniques to investigate the localization, content, transport and release of substance P- and calcitonin gene-related peptide-like immunoreactivity (SP-LI and CGRP-LI, respectively) in nerve fibre endings in 1-, 3- and 5-week-old cutaneous nerve neuromas. Neuromas were induced by ligating and transecting the saphenous nerve in anaesthetized Sprague-Dawley rats. The content of both neuropeptides in 3-week-old saphenous nerve neuroma was significantly reduced compared to that in normal saphenous nerve. At 5 weeks the levels of the peptides in the neuromas had returned to normal but remained reduced in the nerve just proximal to the neuroma. Following a 24-h ligation of the nerve proximal to 3-week-old neuromas there was a diminished immunocytochemical staining for SP-LI and CGRP-LI both proximal and distal to the ligature when compared to that seen at ligations of normal nerves. This indicates a decreased transport of the neuropeptides both to and from the 3-week-old neuromas. The density of neuropeptide staining at ligatures of nerves with 5 week or older neuromas had increased, but still remained less than that seen at ligations of normal nerve. Both a basal and a bradykinin-induced release of SP-LI and CGRP-LI from nerve fibre endings in the neuroma was demonstrated. The basal release was demonstrated by exposing the neuromas, in situ, to solutions containing 50 microM morphine plus 2 mM CoCl2 for 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)
White
D M
DM
II Physiologisches Institut der Universität, Heidelberg, F.R.G.
Leah
J D
JD
Zimmermann
M
M
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D008297:Male; D009411:Nerve Endings / Q000378:metabolism*; D009463:Neuroma / Q000378:metabolism*; D010524:Peripheral Nervous System Neoplasms / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000378:metabolism*
D013373:Substance P; D015740:Calcitonin Gene-Related Peptide; D001920:Bradykinin