Sonic hedgehog signaling controls gut epithelium homeostasis following intestinal ischemia-reperfusion in a rat.

Abstract

One of the major regulators of gastrointestinal tract development is the hedgehog signaling pathway. The purpose of this study was to evaluate the role of sonic hedgehog (SHh) signaling 24 and 48h following intestinal ischemia-reperfusion (IR) in a rat. Male rats were divided into four experimental groups: (1) Sham-24h rats underwent laparotomy and were sacrificed after 24h, (2) Sham-48h rats underwent laparotomy and were sacrificed after 48h, (3) IR-24h rats underwent occlusion of both superior mesenteric artery and portal vein for 20min followed by 24h of reperfusion, and (4) IR-48h rats underwent ischemia for 20min followed by 48h of reperfusion. Intestinal structural changes, enterocyte proliferation and enterocyte apoptosis were determined by immunohistochemistry 24 and 48h following IR. SHh-related genes and protein expression were determined using real-time PCR, Western blot and immunohistochemistry. IR-24 rats demonstrated a significant decrease in Shh, Ihh, GIL and Ptch2 mRNA in jejunum and ileum compared to Sham-24 animals that was accompanied by a significant decrease in the number of SHH-positive cells (Immunohistochemistry) in jejunum (2.5-fold decrease) and ileum (37%). After 48h, IR rats demonstrated a significant increase in Dhh, Ihh, Gil and PTCH2 mRNA in jejunum as well as in Dhh, Ihh, SMO, GIL, PTCH2 mRNA in ileum compared to IR-24 animals that was coincided with increased number of SHH-positive cells in jejunum (2.6-fold increase) and ileum (1.4-fold increase). 24h following intestinal IR, inhibited cell turnover was associated with inhibited SHh signaling pathway. Signs of intestinal recovery appeared 48h after IR and were correlated with increase in SHh signaling pathway activity.