Abstract: Using a behavioral study to characterize the effects of TMP administered by intraplantarlly and intrathecally on the acute nociception（flinching） mediated by P2X receptor activation of rat hindpaw. The P2X₃ receptor antagonist TNP-ATP（0.3μmol/L） significantly depressed the acute nociception mediated by ATP （1 μ mol/L） and α,β -meATP （0.6μmol/L） in rat hindpaw. Intraplantar administration of TMP （0.1-10 mmol/L） inhibited the acute nociception in a dose-dependent manner mediated by ATP （1 μ mol/L） or α，β -meATP （0.6μmol/L） in rat hindpaw. Intrathecal ly applied TMP （50 mmol/L） inhibited the nociception induced by ATP （1 μmol/L） or α , β -meATP （0.6 μ mol/L） in rat hindpaw. TMP inhibited the nociceptive behaviors induced by P2X₃ receptor mediated excitation of nociceptive afferents.

Key words: Rat, Tetramethylpyrazine, ATP, P2X receptors, Nociception, Intraplantar drug administration, Intrathecal drug administration