Potentiation of oxycodone antinociception in mice by agmatine and BMS182874 via an imidazoline I2 receptor-mediated mechanism

► Involvement of imidazoline receptors in oxycodone antinociception was determined. ► Efaroxan (EFX) and BU224 were used to determine involvement of I1 and I2 receptors. ► Oxycodone antinociception was unaffected by efaroxan but was blocked by BU224. ► BU224 but not EFX blocked agmatine/BMS182874-potentiated oxycodone antinociception. ► Imidazoline I2 but not I1 receptors are involved in oxycodone antinociception.