title: Hydration status affects osteopontin expression in the rat kidney.
abstract: Osteopontin (OPN) is a secretory protein that plays an important role in urinary stone formation. Hydration status is associated with the development of urolithiasis. This study was conducted to examine the effects of dehydration and hydration on OPN expression in the rat kidney. Animals were divided into three groups, control, dehydrated, and hydrated. Kidney tissues were processed for light and electron microscope immunocytochemistry, in situhybridization, and immunoblot analysis. Dehydration induced a significant increase in OPN protein expression, whereas increased fluid intake induced a decrease in protein expression. Under control conditions, OPN protein and mRNA expression were only detected in the descending thin limb (DTL). Dehydration induced increased expression in the DTL and the development of detectable expression in the thick ascending limb (TAL). In contrast, OPN expression levels declined to less than the controls in the DTL after hydration, while no expression of either protein or mRNA was detectable in the TAL. Immunoelectron microscopy demonstrated that hydration status altered tubular ultrastructure and intracellular OPN expression in the Golgi apparatus and secretory cytoplasmic vesicles. These data confirm that changes in oral fluid intake can regulate renal tubular epithelial cell OPN expression.
authors.affiliation: Department of Anatomy, Ewha Womans University School of Medicine, Seoul 03760, Korea.
authors.forename: Su-Youn
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Department of Anatomy, Ewha Womans University School of Medicine, Seoul 03760, Korea.
authors.forename: Sae-Jin
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Anatomy, Ewha Womans University School of Medicine, Seoul 03760, Korea.
authors.forename: Hong-Lin
authors.initials: HL
authors.lastname: Piao
authors.affiliation: Department of Anatomy, Ewha Womans University School of Medicine, Seoul 03760, Korea.
authors.forename: Suk-Young
authors.initials: SY
authors.lastname: Yang
authors.affiliation: Division of Nephrology, College of Medicine, University of Florida, Gainesville, FL 32608, USA.|Nephrology Section, North Florida/South Georgia Veterans Health System (NF/SGVHS), Gainesville, FL 32608, USA.
authors.forename: I David
authors.initials: ID
authors.lastname: Weiner
authors.affiliation: Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Anatomy, Ewha Womans University School of Medicine, Seoul 03760, Korea.
authors.forename: Ki-Hwan
authors.initials: KH
authors.lastname: Han
mesh_terms: D000818:Animals; D003890:Desiccation; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology / Q000378:metabolism* / Q000503:physiopathology / Q000648:ultrastructure; D007669:Kidney Calculi / Q000235:genetics* / Q000503:physiopathology / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D053495:Osteopontin / Q000235:genetics* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D053495:Osteopontin
keywords: hydration; osteopontin; renal stone; tubular epithelial cells