Reduced 11beta-hydroxysteroid dehydrogenase activity in the remaining kidney following nephrectomy.
Intracellular access of steroids to gluco- and mineralocorticoid receptors is regulated by reduced 11beta-hydroxysteroid dehydrogenase (OHSD) 1 and 2. These enzymes convert active 11beta-OH-steroids into inactive 11-keto-steroids. The purpose of the present study was to establish whether the 11beta-OHSD1 and 11beta-OHSD2 are modulated in the remnant kidney 24 h or 14 days after uninephrectomy (UNX) in rats. Overall, 11beta-OHSD activity was analyzed by measuring the ratio of the exogenous 11beta-OH-steroid prednisolone to its 11-keto metabolite prednisone in vivo in kidney tissue using high performance liquid chromatography. To determine which isoenzyme accounts for the changed activity 24 h after UNX, the oxidation and reduction attributable to 11beta-OHSD1 and oxidation to 11beta-OHSD2 were analyzed in total renal extracts and in isolated glomeruli, proximal convoluted tubules (PCT), cortical ascending limbs, and cortical convoluted tubules (CCT). The messenger RNA content of 11beta-OHSD1 and 11beta-OHSD2 was measured by RT-PCR in renal tissues and single segments, using glyceraldehyde-3-phosphate-dehydrogenase as an internal standard. Protein amounts of 11beta-OHSD1 and 11beta-OHSD2 were assessed by Western blot. The prednisolone/prednisone ratio increased 24 h after UNX in 9 out of 10 animals (P < or = 0.0011), and was unchanged 14 days after UNX. 11Beta-OHSD1 oxidation (P < or = 0.032) and reduction activity (P < or = 0.002) declined 24 h after UNX in total extracts. 11Beta-OHSD1 oxidase activity was more than 3 times higher in PCT than in glomeruli, cortical ascending limbs, and CCT, and declined by 50% after UNX (P < or = 0.001). The reductase activity did not change following UNX in PCT. 11Beta-OHSD2 activity was 5-15 times higher in CCT than in the other segments, and decreased significantly after UNX (P < or = 0.008). UNX did not affect messenger RNA and protein levels of both enzymes in total renal extracts. In conclusion, 11beta-OHSD1 and 11beta-OHSD2 are predominantly expressed in PCT and CCT, respectively, and their corresponding oxidative activities decline after UNX. Thus, the access of 11beta-glucocorticosteroids to gluco- and mineralocorticoid receptors in the remaining kidney is facilitated after UNX.
Escher
G
G
Department of Medicine, University Hospital of Berne, Inselspital, Switzerland.
Vogt
B
B
Beck
T
T
Guntern
D
D
Frey
B M
BM
Frey
F J
FJ
D042842:11-beta-Hydroxysteroid Dehydrogenases; D000818:Animals; D015153:Blotting, Western; D005260:Female; D006913:Hydroxysteroid Dehydrogenases / Q000032:analysis / Q000378:metabolism*; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D009392:Nephrectomy; D009399:Nephrons / Q000201:enzymology; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D011239:Prednisolone / Q000378:metabolism; D011241:Prednisone / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase; D051381:Rats; D017208:Rats, Wistar
D007527:Isoenzymes; D012333:RNA, Messenger; D011239:Prednisolone; D006913:Hydroxysteroid Dehydrogenases; D042842:11-beta-Hydroxysteroid Dehydrogenases; D012194:RNA-Directed DNA Polymerase; D011241:Prednisone