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Hydration status affects osteopontin expression in the rat kidney

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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 situ hybridization, 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.

No MeSH data available.


Light micrographs illustrating OPN immunostaining in the cortex (A). Occasionally, OPN expression was observed in Bowman's capsules (B, arrows) and distal tubules (inset, arrow). Rectangles mark areas magnified. G, glomerulus; PT, proximal tubule.
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Figure 3: Light micrographs illustrating OPN immunostaining in the cortex (A). Occasionally, OPN expression was observed in Bowman's capsules (B, arrows) and distal tubules (inset, arrow). Rectangles mark areas magnified. G, glomerulus; PT, proximal tubule.

Mentions: Dehydration caused a marked increase in OPN immunoreactivity in the inner stripe of the outer medulla (panel D in Fig. 2). There was a moderate increase in immunoreactivity in the descending thin limb. In addition, strong labeling was present in thick ascending limb segments, notably at the apical surface of the cells (panel E in Fig. 2). Occasionally, a few cells of some distal convoluted tubules and the parietal epithelium of Bowman's capsule exhibited positive immunostaining in the cortex (Fig. 3).


Hydration status affects osteopontin expression in the rat kidney
Light micrographs illustrating OPN immunostaining in the cortex (A). Occasionally, OPN expression was observed in Bowman's capsules (B, arrows) and distal tubules (inset, arrow). Rectangles mark areas magnified. G, glomerulus; PT, proximal tubule.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037293&req=5

Figure 3: Light micrographs illustrating OPN immunostaining in the cortex (A). Occasionally, OPN expression was observed in Bowman's capsules (B, arrows) and distal tubules (inset, arrow). Rectangles mark areas magnified. G, glomerulus; PT, proximal tubule.
Mentions: Dehydration caused a marked increase in OPN immunoreactivity in the inner stripe of the outer medulla (panel D in Fig. 2). There was a moderate increase in immunoreactivity in the descending thin limb. In addition, strong labeling was present in thick ascending limb segments, notably at the apical surface of the cells (panel E in Fig. 2). Occasionally, a few cells of some distal convoluted tubules and the parietal epithelium of Bowman's capsule exhibited positive immunostaining in the cortex (Fig. 3).

View Article: PubMed Central - PubMed

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 situ hybridization, 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.

No MeSH data available.