title: Altered expression of COX-1, COX-2, and mPGES in rats with nephrogenic and central diabetes insipidus.
abstract: Prostaglandins have an important role in renal salt and water reabsorption. PGE2 is the main kidney prostaglandin and is thought to be mainly produced in the kidney inner medulla (IM). There are indications that PGE2 synthesis in nephrogenic (NDI) and central (CDI) diabetes insipidus is altered. We hypothesize that the expression of the major PGE2 synthesis enzymes cyclooxygenases 1 and 2 (COX-1, COX-2) and membrane-associated PGE2 synthase (mPGES) is altered in the kidneys of rats with NDI and CDI. Wistar rats treated with lithium for 4 wk were used as the NDI model. One-half of the NDI model rats were additionally dehydrated for 48 h. Brattleboro (BB) rats that lack endogenous antidiuretic hormone were used as the CDI model. Expression and localization of COX-1, COX-2, and mPGES in IM, inner stripe of outer medulla (ISOM), and cortex were determined by immunoblotting and immunohistochemistry. In lithium-induced NDI, expression of COX-1, COX-2, and mPGES was markedly decreased in IM. In ISOM and cortex, COX-1 expression was marginally reduced and mPGES expression was unaltered. COX-2 expression was undetected in ISOM and marginally increased in cortex. Consistent with this, the density of COX-2-expressing cells in macula densa was significantly increased, indicating differential regulation of COX-2 in IM and cortex. Dehydration of NDI rats resulted in a marked increase in COX-2 immunolabeling in IM interstitial cells, and there was no significant change in COX-1 and mPGES expression in any kidney zone. Treatment of DDAVP in BB rats for 6 days resulted in a markedly increased expression of COX-1, COX-2, and mPGES in IM. In the cortex, there were no changes in the expression of COX-1 and mPGES, whereas COX-2 expression was decreased. These results identify markedly reduced expression of COX-1, COX-2, and mPGES in IM in lithium-induced NDI. Furthermore, there were major changes in the expression of COX-1, COX-2, and mPGES in rats with CDI.
authors.affiliation: The Water and Salt Research Center, University of Aarhus, DK-8000 Aarhus C, Denmark.
authors.forename: Primoz
authors.initials: P
authors.lastname: Kotnik
authors.forename: Jakob
authors.initials: J
authors.lastname: Nielsen
authors.forename: Tae-Hwan
authors.initials: TH
authors.lastname: Kwon
authors.forename: Ciril
authors.initials: C
authors.lastname: Krzisnik
authors.forename: Jørgen
authors.initials: J
authors.lastname: Frøkiaer
authors.forename: Søren
authors.initials: S
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D003681:Dehydration; D018500:Diabetes Insipidus, Nephrogenic / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism*; D020790:Diabetes Insipidus, Neurogenic / Q000188:drug therapy / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis / Q000652:urine; D019746:Intramolecular Oxidoreductases / Q000378:metabolism*; D007671:Kidney Concentrating Ability / Q000187:drug effects; D007672:Kidney Cortex / Q000201:enzymology; D007679:Kidney Medulla / Q000201:enzymology; D008094:Lithium / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins; D011141:Polyuria / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D051381:Rats; D011910:Rats, Brattleboro; D017208:Rats, Wistar; D012076:Renal Agents / Q000494:pharmacology; D014667:Vasopressins / Q000172:deficiency / Q000378:metabolism; D014868:Water Deprivation
chemical_list: D008565:Membrane Proteins; D012076:Renal Agents; D014667:Vasopressins; D008094:Lithium; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D019746:Intramolecular Oxidoreductases; C495729:membrane-associated PGE synthase, rat; D003894:Deamino Arginine Vasopressin; D015232:Dinoprostone