Abstract
Purinergic receptor mechanisms have recently been implicated in peripheral (Rong et al 2000) and central (Hu et al 2002, Chiang et al 2005) nociceptive processing. Of the 7 iontotropic purinergic receptor subtypes (P2X receptor family), the expression of the P2X3 receptor is reported to be much higher than that of the other P2x receptor subtypes in trigeminal ganglia (Xiang et al 1998) and it has recently been found in TMJ tissues (Ichikawa et al 2004, Shinoda et al 2005). To clarify further the role of P2X receptors in TMJ-related functions, the application of P2X receptor agonist to the TMJ elicits nociceptive behaviors (Oliveira et al 2005, Shinoda et al 2005). The first aim of the present study was to test if the application of a P2X receptor agonist to the rat TMJ induces reflex activity in the jaw muscles and if this excitatory effect can be blocked by peripheral application of P2X receptor antagonist. The second aim was to test if blockade of peripheral NMDA receptors can influence the reflex jaw muscle activity evoked by ATP agonist. [J Physiol Sci. 2006;56 Suppl:S157]
