Abstract
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 > urinary bladder > ureter ⪢ distal duodenum ⪢ proximal duodenum ⪢ skin (snout) > 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/SP-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.
Published Version
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