Tephrosia sinapouethyl acetate extract inhibits inflammatory pain in mice: Opioid receptor dependent inhibition of TNFαand IL-1βproduction

The intraperitoneal pre-treatment with extract inhibited in a dose-dependent (30-300 mg/kg) dependent manner the mechanical hyperalgesia induced by carrageenin (up to 93% inhibition). The post-treatment (100 mg/kg) inhibited CFA-induced hyperalgesia (up to 63% inhibition). Naloxone (1 mg/kg) prevented the inhibitory effect of the extract over carrageenin-induced mechanical (100%) and thermal (100%) hyperalgesia, neutrophil recruitment (52%) and TNFα (63%) and IL-1β (98%) production, thermal threshold in naïve mice (99%), PGE2-induced mechanical hyperalgesia (88%) and acetic acid-induced writhing response (49%). There was no significant alteration in the rota-rod test, and AST and ALT serum levels by extract treatment. Discussion and conclusion. Tephrosia sinapou ethyl acetate extract reduces inflammatory pain by activating an opioid receptor-dependent mechanism.