Blockade of Adrenal Medulla-Derived Epinephrine Potentiates Bee Venom-Induced Antinociception in the Mouse Formalin Test: Involvement of Peripheral β-Adrenoceptors
Figure 1
Graphs illustrating the antinociceptive effect of DBV administered at three different doses in normal and adrenalectomized mice, based on analysis of formalin-induced pain responses during the early (a) and late (b) phases of the formalin test. (a) During the early phase, there were no changes in licking behavior in either the normal or adrenalectomized groups treated with DBV at any of the doses tested. (b) During the late phase, administration of a high dose (1 K) of DBV in normal mice significantly inhibited the pain behavior as compared with the vehicle-treated group (***). In adrenalectomized mice, formalin injection produced similar pain responses to those observed in nonadrenalectomized mice. Treatment with DBV (1 K and 10 K) significantly suppressed the paw licking time compared to the vehicle-injected animal group (* and ***), while the lowest dose (100 K) of DBV had no effect on formalin-induced pain responses. Treatment with each of the three doses (1 K, 10 K, and 100 K) of DBV suppressed pain behavior compared to the same dose of DBV administered to the normal mice (nonadrenalectomized) group (# and ##).
