Changes in the PWMT prior to surgery and on days 0, 3, 7, 14 and 21 post-surgery. Compared with the sham group, there was a significant decrease in PWMT following chronic constriction injury (**P<0.01) in each of the remaining groups. Pio administration attenuated the reduction in PWMT on postoperative days 3, 7, 14 and 21 post-surgery compared with the vehicle group (##P<0.01), and this effect was reversed by co-administration with GW. PWMT, paw withdrawal mechanical threshold; Pio, pioglitazone; GW, GW9662.