Figure 1.

Antihyperalgesic effect of PC1 administration as single bolus. (A) CCI of the sciatic nerve caused a marked reduction of the ipsilateral PWL, assessed with the plantar test, from the first day after surgery. PWL reached minimal values on day 3 and returned to normal values 40 days after surgery. (B) PWT, assessed with the von Frey filament stimulation, was clearly reduced in the injured paw from day 12 after CCI reached minimal levels on day 17 and was still significantly lower than in contralateral paw on day 40. Thermal and tactile sensitivity of the contralateral paw remained near the basal level throughout the experiment. (C) Single s.c. administration of PC1 (30, 75 and 150 µg kg⁻¹ s.c.) on day 3 after CCI, when thermal hyperalgesia was maximal, dose-dependently reduced the established CCI-induced thermal hyperalgesia. (D) Single s.c. administration of PC1 (30, 75 and 150 µg kg⁻¹ s.c.) on day 17 after CCI, when allodynia have reached maximum level, dose-dependently reduced the established allodynia. The highest dose (150 µg kg⁻¹ s.c) abolished thermal and tactile hyperalgesia for about 2 h. (E) A single bolus p.n. injection of PC1 (5, 15, 50 ng per mice) in the injured paw on day 3 after CCI dose-dependently reverted the established CCI-induced thermal hypersensitivity. The highest dose of PC1 (50 ng) abolished hyperalgesia for about 2 h. (F) A single bolus i.t. injection of PC1 (1, 10 and 100 ng per mice) induced a rapid, dose-dependent reduction of the established thermal hyperalgesia. The highest dose of PC1 (100 ng) abolished thermal hyperalgesia for about 2 h. Data represent means ± SEM of five mice. *P < 0.05, **P < 0.01, ***P < 0.001 CCI/saline versus sham; °P < 0.05; °°P < 0.01; °°°P < 0.001 CCI/PC1 versus CCI/saline mice; two-way anova, followed by Bonferroni's test.