Growth hormone downregulated the excessive apoptosis of ileal intestinal epithelial cells in rats during the early course of acute necrotizing pancreatitis.

INTRODUCTION: Growth hormone (GH) has beneficial effects in protecting the intestinal barrier integrity of rats with acute necrotizing pancreatitis (ANP), and the balance between apoptosis and proliferation of intestinal epithelium is one of the key factors in maintenance of the intestinal barrier homeostasis. AIM: To evaluate further the effect of GH on cell apoptosis of intestinal epithelium in rats with ANP.
METHODOLOGY: Seventy-two rats were randomly divided into 3 groups: sham operation (SO) group (n = 24); ANP group (n = 24); and ANP with GH treatment group (n = 24). ANP in rats was established by injection of 5% sodium taurocholate into the biliopancreatic duct, and laparotomized animals without induction of ANP (sham operation) served as controls. The rats in the GH treatment group received human recombinant GH (0.75 U/kg body weight) subcutaneously once, immediately after operation. The segment of ileum was removed and the detached epithelial cells of ileum were harvested at 3 hours, 6 hours, 12 hours, and 24 hours after operation. Apoptosis of intestinal epithelium was studied by DNA gel electrophoresis, fluorescein isothiocyanate (FITC)-labeled annexin V and propidium iodide (PI) staining under flow cytometry, and the terminal deoxynucleotidyl transferase-mediated d-UTP-biotin nick end labeling (TUNEL) histochemical method.
RESULTS: All specimens harvested at different time points from rats with ANP showed a marked DNA ladder pattern after agarose gel electrophoresis, in comparison with those in the SO group, indicating DNA fragmentation appeared at the early stage in the ANP group. However, a DNA ladder pattern was seen only at 3 hours after operation in the GH-treated rats. The apoptotic percentage assayed by flow cytometry with use of an annexin V kit at 6 hours in the ANP group was significantly higher than in the control group (80% +/- 9% versus 28% +/- 6%; p < 0.01) and was decreased markedly in the GH treatment group (27% +/- 15% versus 80% +/- 9%, p < 0.01). The apoptotic index, studied by the TUNEL method, was obviously higher in the ANP group than in the control group (3 hours: 18 +/- 4 versus 6 +/- 2; 6 hours: 20 +/- 3 versus 8 +/- 2; 12 hours: 15 +/- 2 versus 11 +/- 1; 24 hours: 14 +/- 2 versus 5 +/- 1; p < 0.01), whereas the apoptotic index in the GH treatment group decreased at 3 hours and 6 hours (10 +/- 2 versus 18 +/- 4; 10 +/- 2 versus 20 +/- 3; p < 0.01). The same results were achieved for the apoptotic index of villi tips in the three groups.
CONCLUSION: Apoptosis is a principle model of intestinal epithelial cell death at the early stage of ANP, and GH may downregulate the apoptosis significantly. This action probably is involved in the mechanisms contributing to the protective effects of GH on intestinal barrier integrity in ANP.