Figure 1.

Effect of pertussis toxin (PTX) pretreatment on clonidine- and guanabenz-induced antinociception in the mouse hot-plate test. (a) Prevention by PTX (0.25 μg per mouse, i.c.v.) of clonidine (0.05–0.20 mg kg⁻¹, s.c.) antinociception. The test was performed 7 days after a single i.c.v. injection of vehicle or PTX. Vertical lines represent s.e.mean; between 11 and 16 mice were tested. ^*P<0.05, ^**P<0.01 in comparison with vehicle-clonidine treated mice. (b) Prevention by PTX (0.25 μg per mouse, i.c.v.) of guanabenz (0.02–0.50 mg kg⁻¹, s.c.) antinociception. The test was performed 7 days after a single i.c.v. injection of vehicle or PTX. Vertical lines represent s.e.mean; between 12 and 19 mice were tested. ^*P<0.05, ^**P<0.01 in comparison with vehicle-guanabenz treated mice.