• International Journal of Oral Biology
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• v.42 no.1
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• pp.1-8
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• 2017

In the present study, we investigated the role of peripheral ionotropic receptors in artemin-induced thermal hyperalgesia in the orofacial area. Male Sprague-Dawley rats weighting 230 to 280 g were used in the study. Under anesthesia, a polyethylene tube was implanted in the subcutaneous area of the vibrissa pad, which enabled drug-injection. After subcutaneous injection of artemin, changes in air-puff thresholds and head withdrawal latency time were evaluated. Subcutaneous injection of artemin (0.5 or $1{\mu}g$) produced significant thermal hyperalgesia in a dose-dependent manner. However, subcutaneous injection of artemin showed no effect on air-puff thresholds. IRTX ($4{\mu}g$), a TRPV1 receptor antagonist, D-AP5 (40 or $80{\mu}g$), an NMDA receptor antagonist, or NBQX (20 or $40{\mu}g$), an AMPA receptor antagonist, was injected subcutaneously 10 min prior to the artemin injection. Pretreatment with IRTX and D-AP5 significantly inhibited the artemin-induced thermal hyperalgesia. In contrast, pretreatment with both doses of NBQX showed no effect on artemin-induced thermal hyperalgesia. Moreover, pretreatment with H-89, a PKA inhibitor, and chelerythrine, a PKC inhibitor, decreased the artemin-induced thermal hyperalgesia. These results suggested that artemin-induced thermal hyperalgesia is mediated by the sensitized peripheral TRPV1 and NMDA receptor via activation of protein kinases.