Oral Biosci Med 2 (2005), No. 4 (27.01.2006)
TRPV1 Receptor Mechanisms Involved in Capsaicin-Induced Oedema in the Temporomandibular Joint Region
Hu, J. W./Fiorentino, P. M./Cairns, B. E./Sessle, B. J.
Purpose: Recent evidence indicates that capsaicin (CAP), the active and pungent ingredient of hot red peppers, can induce inflammation and pain when it is applied to peripheral tissues. It has been shown to excite small-diameter afferent nerve fibers supplying the tissues by acting on a specific membrane receptor, the TRPV1 (or VR1) receptor. Since it is unclear how CAP application produces an inflammatory action in temporomandibular joint (TMJ) tissues, the aim of this study was to determine if CAP application to the rat TMJ region induces inflammatory changes such as oedema through an action on the TRPV1 receptor.
Materials and Methods: In eight groups of anaesthetized rats (each group, n=8), CAP (0.001%, 0.01%, 0.1%, or 1%) was injected into the TMJ region and was preceded by injection of vehicle or the TRPV1 receptor antagonists capsazepine or ruthenium red. Oedema was monitored by expansion of the TMJ tissues.
Results: Compared with vehicle controls, CAP 1%, 0.1% and 0.01% induced significantly greater oedema (p<0.05, ANOVA) in a dose dependent manner. The oedema became apparent as early as 15 minutes after the CAP injection and lasted over 120 minutes. Both the competitive antagonist capsazepine and the non competitive antagonist ruthenium red could significantly reduce the CAP induced oedema.
Conclusions: These findings indicate that CAP can induce a significant inflammatory response within the TMJ region in a dose-dependent fashion, and that this effect is mediated, at least in part, by TRPV1 receptor mechanisms.
Keywords: temporomandibular joint, oedema, capsaicin