Dose-dependent antinociceptive effects of intrathecal mPAP.
(A) Effects of increasing amounts of mPAP on paw withdrawal latency to a radiant heat source. (B) Paw withdrawal threshold to a semi-flexible tip mounted on an electronic von Frey apparatus. (A, B) BL = Baseline. Injection (i.t.) volume was 5 µL. n = 8 wild-type mice were used per dose. There were significant differences over time between mice injected with heat-inactivated (0 U) mPAP and mice injected with active (1 U or 2 U) mPAP (Repeated measure two-way ANOVA; P<0.0001 for each dose). Post-hoc paired t-tests were used to compare responses at each time point between mice injected with active mPAP to mice injected with heat-inactivated mPAP (** P<0.005; *** P<0.0005). For the heat-inactivated mPAP control, the protein concentration was equivalent to the maximum 2 U dose of mPAP (1.1 mg/mL). All data are presented as means±s.e.m.