PROSTAGLANDIN-E-2 MODULATES SEROTONIN-IMMUNOREACTIVE AND GASTRIN CCK-IMMUNOREACTIVE CELLS IN THE DUODENAL MUCOSA OF THE RAT/

Groups of Sprague-Dawley rats were given placebo or prostaglandin E-2 (PGE(2)) at 25 or 5,000 mu g/kg or 15,R,15-methyl-PGE(2) (MePGE(2)) at 5 or 50 mu g/kg, twice daily, orally, for I month. Histological secti ons from the proximal duodenum were processed for immunohistochemistry and the volume density of immunoreactive endocrine cells was determin ed using point-counting grids. The surface density of the villous lini ng was estimated by using a cycloid test system. Thereafter, the total volumes of endocrine cells and the total surface area of the villous lining were calculated after estimating the mucosal volume. The volume density of serotonin-immunoreactive cells was increased in the duoden um of rats given 25 or 5,000 mu g/kg PGE(2) (p < 0.05). The total volu me of these cells increased in the animals given 25 mu g/kg PGE(2) (p < 0.05). The total volume of gastrin/CCK-immunoreactive cells was high er in rats given 25 mu g/kg PGE(2) or 50 mu g/kg MePGE(2) than in cont rols (p < 0.05). The volume density of somatostatin-immunoreactive cel ls increased in rats given 5 mu g/kg MePGE(2), but the total volumes w ere not different between the groups. The area of somatostatin-immunor eactive cell profiles was enlarged in the animals given 5,000 mu g/kg PGE(2) (p < 0.05). The mucosal volume was enlarged by prostaglandins. The epithelial thickness increased in rats given the highest doses of PGE(2) (p < 0.05). The concentration of motilin-like immunoreactivity increased in the duodenum of rats given 5 mu g/kg MePGE(2) (p < 0.05). We conclude that oral administration of PGE(2) for 1 month increased the total volumes of serotonin- and gastrin-CCK-immunoreactive cells a nd the tissue concentration of motilin-like immunoreactivity, which in dicates that prostaglandins modulate endocrine cells in a stable stead y-state condition.