Capsaicin-induced release of neurokinin A from muscle and mucosa of gastric corpus: correlation with capsaicin-evoked release of calcitonin gene-related peptide.
It has been proposed that capsaicin-sensitive nerves might participate in a gastric defence mechanism, possibly via a local release of sensory neuropeptides. In this study, it was examined whether capsaicin might induce the release of neurokinin A (NKA), substance P (SP) and calcitonin gene-related peptide (CGRP) from different regions of rat stomach. Firstly, the tissue content of NKA-, SP- and CGRP-like immunoreactivity (LI) was measured in the fundus, in the corpus, in the muscle layer and in the mucosa of corpus of control rats and rats pre-treated with systemic capsaicin, s.c. (50 mg/kg as newborn). A large depletion (about 80%) of CGRP-LI following capsaicin treatment was observed in all regions examined, while no difference was observed for NKA-LI and SP-LI. NKA-LI, SP-LI and CGRP-LI release induced by capsaicin was measured in different regions of the rat stomach. Both in the gastric fundus and in the corpus, capsaicin (10 microM) produced a remarkable release of of CGRP-LI and NKA-LI, but not of SP-LI. A second administration of the drug had no longer effect, indicating desensitization. In the gastric corpus, the capsaicin-induced NKA-LI and CGRP-LI release was larger from the muscle layer than from the mucosa. The present findings provide neurochemical evidence that both NKA-LI and CGRP-LI are released from different regions of the rat stomach and both peptides should therefore be taken into account when considering the efferent function of capsaicin-sensitive primary afferents at gastric level.
Renzi
D
D
Department of Clinical Pathophysiology, University of Florence, Italy.
Evangelista
S
S
Mantellini
P
P
Santicioli
P
P
Maggi
C A
CA
Geppetti
P
P
Surrenti
C
C
D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D002211:Capsaicin / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008297:Male; D009132:Muscles / Q000187:drug effects / Q000378:metabolism; D015288:Neurokinin A / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013194:Staining and Labeling; D013270:Stomach / Q000187:drug effects; D013373:Substance P / Q000378:metabolism
D013373:Substance P; D015288:Neurokinin A; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin