Vasodilatory effects and coexistence of calcitonin gene-related peptide (CGRP) and substance P in sensory nerves of cat dental pulp.
Substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactivity (-IR) were localized by immunohistochemistry in the same nerve cell bodies in the trigeminal ganglia as well as in nerve terminals of the dental pulp. The distribution of SP- and CGRP-IR nerves were identical in the dental pulp and mainly associated with blood vessels. The level of CGRP-IR in the dental pulp, as measured by radio-immunoassay (RIA), was 1.4 +/- 0.2 pmol g-1 wet wt, which is in the same range as that found for substance P. Local intra-arterial infusion of synthetic CGRP and substance P produced vasodilatation in the dental pulp as measured by both laser Doppler flowmetry and an 125I clearance technique. The CGRP was effective as a vasodilator when infused in the femtomole per minute range, and SP in the picomole range. The effect of CGRP (50 fmol min-1) was 10 times larger when given after SP (15 pmol min-1) than before it. Since the two peptides coexist in the same neurons, it is suggested that they both contribute to the vasodilation seen upon antidromic stimulation of sensory nerves.
D000818:Animals; D015740:Calcitonin Gene-Related Peptide; D002415:Cats; D003782:Dental Pulp / Q000098:blood supply / Q000294:innervation*; D005455:Fluorescent Antibody Technique; D007261:Infusions, Intra-Arterial; D007457:Iodine Radioisotopes; D007834:Lasers; D009479:Neuropeptides / Q000008:administration & dosage / Q000378:metabolism*; D011863:Radioimmunoassay; D012212:Rheology; D011984:Sensory Receptor Cells / Q000378:metabolism*; D013373:Substance P / Q000008:administration & dosage / Q000378:metabolism*; D014276:Trigeminal Nerve / Q000378:metabolism; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000378:metabolism*
D007457:Iodine Radioisotopes; D009479:Neuropeptides; D014665:Vasodilator Agents; D013373:Substance P; D015740:Calcitonin Gene-Related Peptide