Background: β-Blockers reduce temporomandibular joint (TMJ) pain. We asked whether they also reduce TMJ inflammation and, if so, whether this anti-inflammatory effect contributes to its analgesic action.
Methods: We measured many parameters of the inflammatory response after co-administration of the β-blocker propranolol with the inflammatory agent carrageenan in the TMJ of female rats. We also hypothesized that the activation of β-adrenoceptors in the TMJ induces nociception mediated, at least in part, by the inflammatory response. To test this hypothesis, we examined the nociceptive response induced by the activation of the β-adrenoceptors in the TMJ in female rats pretreated with thalidomide and fucoidan.
Results: We found that the co-administration of propranolol with carrageenan in the TMJ of female rats significantly reduced several parameters of the inflammatory response induced by carrageenan such as plasma extravasation, neutrophil migration and the release of the pro-inflammatory cytokines TNF-α, IL-1β and CINC-1. Furthermore, the injection of the β-adrenergic receptor agonist isoproterenol in the TMJ induced nociception that was significantly reduced by thalidomide, fucoidan and by the co-administration of propranolol but not of the α-adrenergic receptor antagonist phentolamine.
Conclusions: Propranolol has anti-inflammatory effects that contribute to its antinociceptive action in the TMJ of females.
Significance: β-Blockers have an anti-inflammatory effect on temporomandibular joint (TMJ) that contributes to its analgesic effect. The results of this work suggest that β-blockers can be used to treat the painful conditions of TMJ, especially when they are associated with an inflammatory process.
© 2017 European Pain Federation - EFIC®.