Co-immunostaining for keratin and bromo-2-deoxyuridine (BrdU) in the hindpaw skin four weeks post-fracture. (A) Top panels are images from a normal control rat, middle panels are from a fracture rat, and lower panels are from a fracture rat treated with an NK1 receptor antagonist (LY303870 20 mg/kg, i.p. daily for 8 days), showing keratin staining (red) and BrdU (a marker of DNA synthesis) staining (green). Fracture increased BrdU staining in keratinocytes, indicating increased cellular proliferation, and LY303870 treatment prevented this increase. Scale bar = 50 μm. (B) There was a 3.3 fold increase in BrdU-positive cell numbers at 4 weeks post-fracture in the ipsilateral fracture paw (FX-IPSI), but not in the contralateral paw (FX-CONTRA), and this increase was blocked in fractured rats treated with LY303870 (FX + LY303870). Data were analyzed using one-way analysis of variance (ANOVA) followed by Neuman-Keuls multiple comparison test. ***P < 0.001 for FX-IPSI (n = 9) vs. control (n = 9), and ###
P < 0.001 for FX + LY303870 (n = 4) and FX-CONTRA (n = 9) vs. FX-IPSI cohorts.