Determination of hindpaw skin cytokine and NGF levels at 3 weeks after fracture (FX) in WT, SP deficient (SP KO, Tac1−/−
), and CGRP receptor deficient (RAMP1 KO, RAMP1−/−
) mice. TNFα (A, E), IL-1β (B, F), IL-6 (C, G) and NGF (D, H) production in hindpaw skin were determined by Bio-Rad bead suspension array (for cytokines) and EIA (for NGF). Baseline cytokine and NGF levels were the same in all 3 groups of mice. Tibia fracture induced a significant increase in all three cytokine levels and NGF production in WT FX group vs WT Controls, however, fracture did not induce increased TNFα (A), IL-1β (B), or NGF (D) levels in SP KO FX mice compared to unfractured SP KO Control mice. The IL-6 (C) levels were elevated in the SP KO FX mice, compared to unfractured SP KO Control mice, but the IL-6 increase the SP KO FX mice was considerable reduced compared to the IL-6 levels in the WT FX mice. A similar pattern was observed in the RAMP1 KO mice for TNFα (E), IL-1β (F), or NGF (H), except the increase in IL-6 (G) levels in the RAMP1 KO FX mice was even greater than the increase observed in the WT FX mice. Data are expressed as mean values (pg/mg protein) ± SE (n = 8 per group). *P < 0.05, **P < 0.001, and ***P < 0.0001 vs the respective unfractured Control mice; #P < 0.05, ##P < 0.001, and ###P < 0.0001 vs WT FX mice.