Distribution of calcitonin gene-related peptide-like immunoreactivity in various rat tissues: correlation with substance P and other tachykinins and sensitivity to capsaicin.
Calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) has been measured in various tissues of control rats and rats pretreated with systemic capsaicin, s.c. (50 mg/kg as newborns or as adults, 125 mg/kg as adults) and compared with the tissue level of substance P- and tachykinin-like immunoreactivities (SP-LI and TK-LI). The rank order of CGRP-LI concentration in various tissues was as follows: trigeminal ganglion greater than urinary bladder greater than ureter much greater than distal duodenum much greater than proximal duodenum much greater than skin (snout) greater than thymus = right atrium = vas deferens. A complete depletion of CGRP-LI following capsaicin treatment of both adult and newborn animals was observed in urinary bladder, ureter, atrium, vas deferens and skin. Capsaicin pretreatment of both adult and newborn rats reduced CGRP-LI in the duodenum by about 50%. CGRP-LI in trigeminal ganglion was reduced only in newborn animals, while it was not affected in the thymus. The CGRP-LI/SO-LI ratio varied in these tissues between 33.2 (urinary bladder) and 0.9 (proximal duodenum). A significant correlation was found between CGRP-LI and SP-LI or TK-LI in tissues where immunoreactivities were depleted by capsaicin, as well as in the urinary bladder of individual animals. The correlation between CGRP-LI with SP-LI and TK-LI upon treatment with capsaicin indicates that neurons containing SP and TK as well as CGRP, and neurons containing CGRP only, are affected in a similar manner by capsaicin.
Geppetti
P
P
Institute of Internal Medicine and Clinical Pharmacology, University of Florence, Italy.
Frilli
S
S
Renzi
D
D
Santicioli
P
P
Maggi
C A
CA
Theodorsson
E
E
Fanciullacci
M
M
D000818:Animals; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin / Q000494:pharmacology*; D005260:Female; D008297:Male; D009479:Neuropeptides / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000276:immunology / Q000378:metabolism*; D015320:Tachykinins / Q000276:immunology / Q000378:metabolism; D014018:Tissue Distribution
D009479:Neuropeptides; D015320:Tachykinins; D013373:Substance P; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin