Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Beubler, E; Schuligoi, R; Chopra, AK; Ribardo, DA; Peskar, BA.
Cholera toxin induces prostaglandin synthesis via post-transcriptional activation of cyclooxygenase-2 in the rat jejunum.
J Pharmacol Exp Ther. 2001; 297(3):940-945
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- Führende Autor*innen der Med Uni Graz
- Beubler Eckhard
- Co-Autor*innen der Med Uni Graz
- Peskar Bernhard
- Schuligoi Rufina
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- Abstract:
- The mechanisms of diarrhea in Asiatic cholera have been studied extensively. Cyclic AMP, 5-hydroxytryptamine, prostaglandins, and the function of neuronal structures have been implicated in the pathogenesis of cholera. To elucidate the role of the different isoforms (COX-1 and COX-2) of cyclooxygenase in cholera toxin (CT)-induced fluid secretion and intraluminal prostaglandin E(2) (PGE(2)) release in the rat jejunum in vivo, the effects of the COX-2 inhibitors NS-398 ([N-(2-cyclohexaloxy-4-nitrophenyl)methanesulfonamide]) and DFU [5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulfonyl)phenyl-2(5H)-furanone], and of the COX-1 inhibitor SC-560, were studied. Net fluid transport was measured gravimetrically and PGE(2) by radioimmunoassay. COX-1 and COX-2 mRNA expression were determined by reverse transcription-polymerase chain reaction (RT-PCR) and COX-2 protein by Western blot analysis in mucosal scrapings. CT caused profuse net fluid secretion in all control rats. The COX-2 inhibitors NS-398 and DFU, but not the COX-1 inhibitor SC-560 or dexamethasone, dose-dependently inhibited CT-induced fluid secretion and PGE(2) release. RT-PCR showed expression of COX-1 and of COX-2 mRNA in control rats. CT did not induce an increase and dexamethasone did not reduce COX-2 mRNA, whereas lipopolysaccharide caused a marked induction of COX-2 mRNA, which was inhibited by dexamethasone. A weak band of COX-2 protein was observed in controls; however, CT enhanced COX-2 levels, which remained unaffected by dexamethasone. It can be assumed that post-transcriptional modulation is responsible for CT-induced increase in COX-2 protein. COX-1 does not seem to be involved. Therefore, PGE(2) produced by COX-2 seems to be responsible for the profuse fluid secretion induced by CT, and COX-2 appears to be a specific target for the treatment of Asiatic cholera.
- Find related publications in this database (using NLM MeSH Indexing)
- Animals -
- Blotting, Western -
- Cholera Toxin - pharmacology
- Cyclooxygenase 1 - pharmacology
- Cyclooxygenase 2 - pharmacology
- Cyclooxygenase 2 Inhibitors - pharmacology
- Cyclooxygenase Inhibitors - pharmacology
- Dexamethasone - pharmacology
- Dinoprostone - biosynthesis
- Dose-Response Relationship, Drug - biosynthesis
- Female - biosynthesis
- Furans - pharmacology
- Glucocorticoids - pharmacology
- Intestinal Mucosa - drug effects
- Isoenzymes - antagonists and inhibitors
- Jejunum - drug effects
- Lipopolysaccharides - pharmacology
- Membrane Proteins - pharmacology
- Nitrobenzenes - pharmacology
- Prostaglandin-Endoperoxide Synthases - genetics
- Protein Processing, Post-Translational - drug effects
- Pyrazoles - pharmacology
- RNA, Messenger - metabolism
- Rats - metabolism
- Reverse Transcriptase Polymerase Chain Reaction - metabolism
- Sulfonamides - pharmacology