Epidermal growth factor upregulates serotonin transporter and its association with visceral hypersensitivity in irritable bowel syndrome

Figure 4 Effects of epidermal growth factor on serotonin transporter in rat intestinal epithelial cells. Intestinal epithelial cells (IEC-6) cells were treated with epidermal growth factor (EGF) (0, 20, 40, 60, and 80 ng/mL) for 24 h. A: Western blots were performed to detected serotonin transporter (SERT) protein expressions. GAPDH was used to verify equivalent protein loading (^aP < 0.05 vs control; ^cP < 0.05 vs 20, 80, and 160 ng/mL); B: SERT gene expression was examined by real-time PCR (^aP < 0.05 vs control; ^eP < 0.05 vs 20 and 80 ng/L). To determine the optimal time for EGF treatment, IEC-6 cells were treated with EGF (40 ng/L) for the indicated times (0, 3, 6, 12, 24, and 48 h); C: SERT protein levels were examined by Western blot (^aP < 0.05 vs control); D: SERT gene expression was examined by real-time PCR (^aP < 0.05 vs control; ^gP < 0.05 vs 48 h); E: Uptake of [³H]-serotonin in cells pre-treated with 40 ng/ml EGF for 24 h (^IP < 0.05 vs 24 h) . All values are mean ± SD of three independent experiments.