Fig. 5.

LPS-mediated PGE₂ radioprotects intestine. (A) LPS or dmPGE₂ treatment before IR inhibits apoptosis. Mice received LPS or dmPGE₂ as shown in Fig. 4a, along with indomethacin or NS398. The number of apoptotic cells per crypt was determined after terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining. Values are mean ± SEM (n = 3 mice). a, P < 0.001 compared with control; b, P < 0.001 compared to LPS alone; c, P < 0.002 compared to dmPGE₂ alone. (B) LPS or dmPGE₂ treatment protects crypt stem cells. Two hours before death, BrdUrd was administered to the mice to label the S-phase cells. Sections were immunostained for BrdUrd and scored (n = 3 mice). a, P < 0.001 compared to radiated controls; b, P < 0.001 compared to LPS-treated; c, P = 0.1 compared to dmPGE₂-treated. (C) Schematic representation of the antagonistic activity of CUGBP2- and COX-2-dependent PGE₂ on apoptosis in intestinal epithelial cells.