Simultaneous Inhibition of PGE2 and PGI2 Signals Is Necessary to Suppress Hyperalgesia in Rat Inflammatory Pain Models
Analgesic effect of compound I and/or RO3244019 in acute and chronic inflammatory pain models. (a) Results of adjuvant-induced chronic inflammatory pain model. Male Lewis rats received a single, right hind-paw intradermal injection of M. butyricum (100 g/0.05 mL/paw) in a liquid paraffin emulsion on Day 0. At Day 19, animals with established hyperalgesia (pain score = 5) were orally administered compounds or 0.5% MC. Pain response was examined 1, 2, 3, and 4 h after administration. (b) Male Wistar-Imamichi rats received a single, right hind-paw intradermal injection of dead Brewer’s yeast (20%/0.1 mL/paw). After 18.5 h, compounds or 0.5% MC were administered orally to animals with established hyperalgesia (pain threshold: 60 g–120 g). Pain threshold was measured 1, 2, 3, and 4 h after administration. Results are shown as the mean ± SEM ( = 6/group). The statistical analysis was performed by Steel’s test for multiple comparisons. for compound treated versus 0.5% MC (0 mg/kg) treated animals.