VEGFR-1 tyrosine kinase deficiency reduced expression of pain-related targets in the dorsal root ganglion (DRG) after disc stabbing surgery. (A, C & E) Double immunofluorescence staining of NGF (A), CGRP (C) or TRPV1 (E) with NeuN (green) labeled neurons in DRGs of each group of mice. Co-localization of the two stains appears yellow. 4, 6-diamidino-2-phenylindole (DAPI) stains nuclei blue. Bars=20 μm. (B, D &F) Quantitative analyses show that expression of NGF, CGRP and TRPV1 in DRGs from the DDD group of vegfr-1TK−/− mice was significantly lower than that from the DDD group of WT mice at 12 weeks after surgery. (n=5 per group) (Values are mean ± SD. **P< 0.01, ***P< 0.001).