Tes7370

All rats were habituated to the environment prior to behavioral testing [44 (link)]. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of rats were measured on days 0, 3, 7, and 14 after CCI induction [9 (link)]. The 0-day was considered the day before CCI induction. A series of Von Frey filaments (2, 4, 6, 8, 10, and 15 g) (North Coast Medical, San Jose, CA, USA) was utilized to determine MWT value [16 (link)]. A plantar algometer (Tes7370, Ugo Basile, Comerio, Italy) was used to measure TWL value on the plantar surface of rat paws.

To measure the paw withdrawal mechanical threshold (PWMT), rats were placed in a plastic cage with a metal mesh floor, and Von Frey filaments (North Coast Medical, San Jose, CA, United States) ranging from .4 to 26 g were applied vertically to the plantar surface of the left hind paw until the filament was slightly bent, as described in our previous studies (Shen et al., 2020 (link); Zhang et al., 2022 (link)). The paw withdrawal threshold was determined using the up-and-down method. The PWMT was recorded as the minimum stimulus force required to induce withdrawal responses (lifting or licking).
We used a thermal pain test instrument (Tes7370, Ugo Basile, Comerio, Italy) to test the paw withdrawal thermal latency (PWTL) (Shen et al., 2020 (link); Zhang et al., 2022 (link)). Briefly, rats were placed in the same chamber, which was placed on a 2-mm-thick heat-conducting glass plate. The rats were irradiated with a radiant heat source stimulator (cut-off time: 30 s) on the plantar surface of the left hind paw, and the thermal withdrawal latency was recorded. We repeated the measurement three times at 5-min intervals, and the mean latency was calculated as the PWTL.
The PWMT and PWTL of rats were measured 1 day before and 1–7 days after surgery, respectively. All behavioral tests were performed after the rats were acclimated to a specific individual chamber for at least 30 min.