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Intrinsic Regulation of CGRP Release by Dental Pulp Sympathetic Fibers

¹ Department of Endodontics, UTHSCSA School of Dentistry, Mail Code 7892, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900;
² Division of Endodontics, University of Minnesota School of Dentistry; and
³ Department of Oral Medicine, University of Washington School of Dentistry;

^* corresponding author, Hargreaves{at}UTHSCSA.edu

Neurotransmission from sympathetic and peptidergic afferent fibers participates in the regulation of pulpal blood flow (PBF) via opposing effects. In this study, we directly tested the hypothesis that activation of pulpal sympathetic terminals inhibits exocytosis of immunoreactive calcitonin gene-related peptide (iCGRP) from peptidergic afferents innervating bovine dental pulp. The results demonstrate that norepinephrine inhibits capsaicin-evoked iCGRP release. The application of -adrenergic antagonists (phentolamine or phenoxybenzamine) increased spontaneous release of iCGRP. Moreover, administration of agents that evoke the release of sympathetic neurotransmitters (guanethidine or reserpine) inhibited capsaicin-evoked iCGRP release. Collectively, these results indicate that sympathetic neurotransmission inhibits exocytosis from pulpal peptidergic afferent fibers. Analysis of these data supports the hypothesis that peripheral sympathetic vasomotor control may operate by a direct mechanism (vasoconstriction) as well as by an indirect mechanism (e.g., inhibition of exocytosis from afferent fibers). Since capsaicin-sensitive neurons are nociceptors, it is possible that certain sympathetic neurotransmission may modulate pain.

KEY WORDS: dental pulp • sympathetic • capsaicin • CGRP

This article has been cited by other articles:

				J.L. Gibbs and K.M. Hargreaves Neuropeptide Y Y1 Receptor Effects on Pulpal Nociceptors J. Dent. Res., October 1, 2008; 87(10): 948 - 952. [Abstract] [Full Text] [PDF]