Expression of transforming growth factor (TGF) – β during healing of indomethacin-induced small intestinal ulcers in rats *
Background : The role of transforming growth factor (TGF) -β in the healing of small intestinal mucosal injury is not clearly understood. The aim of this study was to characterize the expression of TGF-β and to assess the effect of lecithin on indomethacin-induced small intestinal ulcers in rats. Materials and methods : 1) Small intestinal ulcers were induced by intracolonic indomethacin in male Wistar rat The expression and localization of TGF-β protein were determined immunohistochemically. The number of TGF-β positive cells at the mesenteric and anti-mesenteric sides of the small intestine was compared between indomethacin-treated group and control group. 2) After the induction of ulcers, the rats were divided into two treatment groups and an untreated group, The former groups were treated with either lecithin dissolved in 2.5% ethanol solution (lecithin group)or with 2.5% ethanol solution alone (vehicle groups). Small intestinal damage was assessed by the ulcer index of length (UIL). the ulcer index of width (UIW), the wall thickness of the ulcer base (WT) and the number of TGF-β positive cells. Results: 1) TGF-β positive cells were found in the lamina propria and the submucosa. The number of positive cells at both the mesenteric and anti-mesenteric sides increased more significantly in the indomethacin-treated group than in the control group from 3 to 24 hours after the treatment. From 3 to 7 days. positive cells increased only at the anti-mesenteric side. At 21 days, the value was significantly higher at the mesenteric side, 2) The number of TGF-β positive cells at the anti-mesenteric side increased more significantly in the lecithin group and the vehicle group than in the untreated group at 14 days. At this time point, UIW and WT were significantly lower in the lecithin group than in the untreated group. Conclusion ; The expression of TGF-β seems to increase during the early phase of small intestinal mucosal injury. During the healing stage, lecithin possibly reduces wall thickness on the affected site without attenuating the expression of TGF-β (Accepted on October 12, 2000) Kawasaki Igakkaishi 26(4) : 223-232. 2000
