Activation of trigeminal nociceptive neurons by parotid PAR-2 activation in rats.

Neuroreport

Division of Physiology and Pathophysiology, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502, Japan.

Published: July 2004

To clarify involvement of protease-activated receptor-2 (PAR-2) in parotid pain, we examined whether PAR-2 activation in the parotid gland could activate trigeminal nociceptive neurons in anesthetized rats, by analyzing immunoreactive Fos as a nociceptive marker. Either the PAR-2 agonist SLIGRL-NH2 or capsaicin, injected into the parotid duct, caused expression of Fos in the trigeminal subnucleus caudalis, although the PAR-2-inactive reversed peptide had no such effect. The Fos expression caused by PAR-2 activation was inhibited by ablation of capsaicin-sensitive sensory neurons. Intraductal SLIGRL-NH2 did not increase vascular permeability in the parotid gland. Our data thus reveal that activation of PAR-2 in the parotid gland can cause activation of trigeminal nociceptive neurons via capsaicin-sensitive sensory nerves most probably by a non-inflammatory mechanism.

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http://dx.doi.org/10.1097/01.wnr.0000134991.97051.6bDOI Listing

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