Effects of prostaglandins on ornithine decarboxylase activity in rat small intestine.
Role of prostaglandins on feeding-associated induction of ornithine decarboxylase in small intestine was studied. Rats received intraperitoneal injection of either saline, or 16,16-dimethyl prostaglandin E2, or TRY-200 (a stable prostaglandin I2 analog), or refeeding, after a 44 hr-fast. Four hours later, mucosae from duodenum, jejunum, and ileum were scraped for subsequent measurements of enzyme activity of ornithine decarboxylase by a radiometric technique. Refeeding resulted in a profound induction of enzyme activity throughout the small intestine. Parenteral administration of prostaglandin I2 also led to a significant induction with the level similar to refeeding. The stimulatory effect of prostaglandin I2 was completely abolished by a specific and irreversible enzyme inhibitor, difluoromethylornithine. Prostaglandin E2 had a similar but lesser effect than prostaglandin I2 on the induction of the enzyme activity. Pretreatment with indomethacin, a cyclooxygenase inhibitor had no effect on feeding-associated enzyme induction. These results indicate that although exogenous prostaglandin I2 appears to be a potent stimulant for ornithine decarboxylase activity in rat small intestine, endogenous prostaglandins seem to play little or no role in feeding-associated induction of ornithine decarboxylase.
Department of Medicine, Nihon University School of Medicine, Tokyo.
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Kuwayama
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Naito
D000704:Analysis of Variance; D000818:Animals; D015232:Dinoprostone / Q000494:pharmacology*; D000518:Eflornithine / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D011464:Epoprostenol / Q000031:analogs & derivatives / Q000494:pharmacology*; D005215:Fasting / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000201:enzymology; D007421:Intestine, Small / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D009955:Ornithine Decarboxylase / Q000096:biosynthesis / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
C071408:TRY 200; D011464:Epoprostenol; D009955:Ornithine Decarboxylase; D015232:Dinoprostone; D000518:Eflornithine