Cimetidine does not change the effect of Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) on the opiate form of footshock-induced analgesia.

It has been demonstrated that cimetidine blocks the effect of naloxone on footshock-induced analgesia. To study the effect of cimetidine on the antiopiate properties of an endogenous peptide Tyr-MIF-1, the opiate form of intermittent footshock-induced analgesia was elicited in the rat. The nociceptive responses were determined using the hot-plate test (52.5 degrees C). Intraperitoneal pretreatment with cimetidine (100 mg/kg) or chlorpheniramine maleate (20 mg/kg) did not affect the footshock-induced analgesia, and did not change the antagonizing effect of Tyr-MIF-1 (0.2 mg/kg) on this model of antinociception. It is concluded that cimetidine and chlorpheniramine maleate do not change the antagonizing effect of Tyr-MIF-1 on the opiate form of intermittent footshock-induced analgesia.