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Figure 5 | Journal of Biomedical Science

Figure 5

From: DNIC-mediated analgesia produced by a supramaximal electrical or a high-dose formalin conditioning stimulus: roles of opioid and α2-adrenergic receptors

Figure 5

Contribution of the opioidergic pathway to DNIC. The opioid receptor was antagonized by a 2 mg/kg intraperitoneal naloxone injection at time point 15 and 1 mg/kg at time point 30. Naloxone itself did not alter the tail-flick latency in the control group (A, the C+Nal line). (A, B) The E50-induced DNIC was not reversed by naloxone administration, whereas the Fm20-induced DNIC was reversed in both the early and late phases by time point-to-point comparisons (C) or by total pain summation (D). Veh, saline; Nal, naloxone. The horizontal thick bar indicates the electrical stimulating period. Rat numbers: E50+Veh = 9, E50+NAL = 7, C+NAL = 9, Fm20+Veh = 10, Fm20+Nal = 9. ** p < 0.01, *** p < 0.001 vs. C+Nal; # p < 0.05 vs. Fm20+Nal; one-way ANOVA with Bonferroni's post hoc test.

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