Figure 2.

GsMTx-4 reverses mechanical hyperalgesia associated with inflammation. A, Intradermal injection of the simplified inflammatory soup (PGE₂ and 5-HT, 100 ng each) induces a decrease in mechanical threshold that was reversed by intradermal injection of GsMTx-4 (1000 ng) at the same site (116 ± 2 g, n = 12 for baseline; 72 ± 1 g, n = 12 after PGE₂ and 5-HT; and 116 ± 2 g, n = 6 after GsMTx-4; *p < 0.001, Tukey's post hoc multiple comparison test). B, Intradermal injection of carrageenan (1%, 5 μl) in rat hindpaw induces a significant decrease in mechanical nociceptive threshold that was reversed by intradermal injection of GsMTx-4 (1000 ng) at the same site (118 ± 1 g for baseline, 75 ± 2 g after carrageenan, and 113 ± 3 g after GsMTx-4; n = 8; *p < 0.001, Tukey's post hoc multiple comparison test). The effect of GsMTx-4 is reversible; 24 h after its administration, the decrease in mechanical threshold was not significantly different from pre-GsMTx-4 baseline (p > 0.05, Tukey's post hoc multiple comparison test).