Effect of PPARγ on the analgesic effects of pioglitazone

ZHAO Xiao-yuan; SHI Hong; WEI Chao; HONG Li-zhi; ZHANG Hui-ling

Abstract：Objective: To investigate the analgesia induced by pioglitazone (Piog), a potent peroxisome proliferator-activated receptor gamma (PPARγ) agonist, and the influence of PPARγ on the analgesic effects of Pi-og. Methods: Piog was administered intraperitoneally (0.78, 1.25 and 2 mg·kg~(-1), ip) or intra-cerebral ventric-ularly (0.02 or 0.04 mg·kg~(-1), icy). The antinociceptive action was tested using the acetic acid writhing test in mice. The involvement of PPARγ in Piog-induced analgesia was examined by pretreatment of mice with a selective PPARγ/antagonist GW9662 (1, 0.5 μg·kg~(-1), ip or 5, 10 μg·kg~(-1), icy). Results: Piog (0.78, 1.25 or 2 mg·kg~(-1), ip) exhibited a dose-dependent analgesic action in mice using acetic acid writhing test. In the mouse acid writhing test, the intra-cerebral ventricle administration of Piog (1/50th of a systemic dose) produced marked analgesic effects. The specific PPARγ antagonist GW9662 (1 mg·kg~(-1), ip or 5, 10 μg·kg~(-1), icy) abolished the Piog-mediated analgesia in the mouse acetic acid writhing test. Conclusion: Piog shows analgesic effect. Central nervous system may be involved in Piog's analgesic effect. The central PPARγ appears to be associated with the antinociception of Piog.