Figure 2.

A: NT/NTR1 signaling promotes the expression of VEGF. NCM460-NTR1 cells were treated as indicated with 10⁻⁷-mol/L NT. VEGF mRNA levels were assessed by qPCR. Results are representative of two separate experiments. B: VEGF protein levels were assessed at indicated time points by enzyme-linked immunosorbent assay. C: NTR1-KO mice or WT littermates received as indicated intracolonic enema of TNBS (250 mg/kg). Forty-eight hours later, mice were sacrificed and colon tissues were collected for RNA isolation. The levels of VEGFα expression were detected by qPCR. Results are representative of two separate experiments. D: C57BL6J mice received intracolonic enema of 250 mg/kg TNBS, and 48 hours later mice received intracolonic enema of 300 μg/kg NT twice a day (8 hours apart) for the following 4 days. Mice were sacrificed on the 6th day, colon tissues were isolated, and VEGF mRNA levels in colon samples were assessed by qPCR. Results are representative of two separate experiments. Data are expressed as means ± SEM. n = 3 (A); n = 6 (B); n = 8 per group (C and D). ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001 (Student's t-test).