A novel mechanism involved in 5-hydroxytryptamine-induced nociception : the indirect activation of primary afferents
C. H. Tambeli, M. C. G. Oliveira, J. T. Clemente, A. Pelegrini-da-Silva, C. A. Parada
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The aim of this study was to test the hypothesis that 5-hydroxytryptamine induces nociception by an indirect action on the primary afferent nociceptor in addition to its previously described direct action. Injection of 5-hydroxytryptamine into the s.c. tissue of the hind paw of rats produced...
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The aim of this study was to test the hypothesis that 5-hydroxytryptamine induces nociception by an indirect action on the primary afferent nociceptor in addition to its previously described direct action. Injection of 5-hydroxytryptamine into the s.c. tissue of the hind paw of rats produced nociceptive flinch behavior and inflammatory cell migration, that were significantly reduced by the nonspecific selectin inhibitor fucoidan. 5-Hydroxytryptamine-induced nociception was also significantly reduced by local blockade of the 5-HT3 receptor by tropisetron, by the cyclooxygenase inhibitor indomethacin and by local blockade of the beta1-adrenergic receptor or of the D1 receptor by atenolol or SCH 23390, respectively. Neither guanethidine depletion of norepinephrine in the sympathetic terminals nor local blockade of the beta2-adrenergic receptor by ICI-118,551 significantly reduced 5-hydroxytryptamine-induced nociception. Taken together, these findings indicate that 5-hydroxytryptamine induces nociception by a novel, indirect and norepinephrine-independent mechanism mediated by neutrophil migration and local release of prostaglandin and dopamine. Furthermore, to test whether dopamine acts on beta1-adrenergic and/or D1 receptor to contribute to 5-hydroxytryptamine-induced nociception, dopamine was s.c. injected either alone or combined with atenolol or with SCH 23390. S.c.-injected dopamine also produced a dose-dependent nociceptive behavior that was significantly reduced by both SCH 23390 and atenolol. Based on that it is proposed that dopamine, once released, activates D1 and beta1-adrenergic receptors to contribute to 5-hydroxytryptamine-induced nociception
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A novel mechanism involved in 5-hydroxytryptamine-induced nociception : the indirect activation of primary afferents
C. H. Tambeli, M. C. G. Oliveira, J. T. Clemente, A. Pelegrini-da-Silva, C. A. Parada
A novel mechanism involved in 5-hydroxytryptamine-induced nociception : the indirect activation of primary afferents
C. H. Tambeli, M. C. G. Oliveira, J. T. Clemente, A. Pelegrini-da-Silva, C. A. Parada
Fontes
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Neuroscience Vol. 141, no. 3 (Sept., 2006), p. 1517-1524 |