Abstract
Previous studies by our group have demonstrated that angiotensin-converting enzyme (ACE) inhibition in the developing kidney modulates transforming growth factor-beta receptors. Blocking of angiotensin II (ANG II) mainly through angiotensin II type 1 receptor (AT1) has been implicated in mediating this ACE inhibition. The present study was designed to investigate the effects of an AT1 antagonist, losartan, on transforming growth factor-beta1 (TGF-beta1), TGF-beta receptor I [TbetaRI, activin-like kinase (ALK)-1, ALK-5], TGF-beta receptor II (TbetaRII), and alpha-smooth muscle actin (alpha-SMA) expression in the developing kidney. Newborn rat pups were treated with losartan (30 mg/kg per day) or normal saline for 7 days. Kidneys were removed for immunohistochemistry, reverse transcription polymerase chain reaction (PCR), and Western blotting of TGF-beta1, ALK-1, ALK-5, TbetaRII, and alpha-SMA. Renal ALK-5 and TbetaRII protein expressions in the losartan-treated group were found to be significantly increased (P<0.05), whereas TGF-beta1, ALK-1, and alpha-SMA protein expressions were not changed by losartan treatment. The losartan-treated group also showed significantly increased mean tubular diameter and interstitial area of the kidney (P<0.05). These results suggest that AT1 inhibition in the developing kidney impairs renal growth and development and modulates the expression of ALK-5 and TbetaRII.
MeSH terms
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Actins / genetics
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Actins / metabolism
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Activin Receptors, Type I / drug effects
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Activin Receptors, Type I / genetics
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Activin Receptors, Type I / metabolism*
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Angiotensin II / antagonists & inhibitors
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Angiotensin II / physiology
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Angiotensin II Type 1 Receptor Blockers / pharmacology*
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Angiotensin-Converting Enzyme Inhibitors / pharmacology
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Animals
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Animals, Newborn / metabolism
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Enzyme Inhibitors / pharmacology
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Female
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Gene Expression Regulation, Developmental / drug effects
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Gene Expression Regulation, Developmental / physiology
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Kidney / drug effects
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Kidney / growth & development*
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Kidney / metabolism*
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Losartan / pharmacology*
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Pregnancy
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Protein Serine-Threonine Kinases
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Rats
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Rats, Sprague-Dawley
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Receptor, Angiotensin, Type 1 / drug effects*
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Receptor, Angiotensin, Type 1 / physiology
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Receptor, Transforming Growth Factor-beta Type I
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Receptor, Transforming Growth Factor-beta Type II
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Receptors, Transforming Growth Factor beta / drug effects
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Receptors, Transforming Growth Factor beta / genetics
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Receptors, Transforming Growth Factor beta / metabolism*
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Transforming Growth Factor beta1 / genetics
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Transforming Growth Factor beta1 / metabolism
Substances
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Actins
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Angiotensin II Type 1 Receptor Blockers
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Angiotensin-Converting Enzyme Inhibitors
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Enzyme Inhibitors
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RNA, Messenger
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Receptor, Angiotensin, Type 1
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Receptors, Transforming Growth Factor beta
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Transforming Growth Factor beta1
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smooth muscle actin, rat
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Angiotensin II
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Protein Serine-Threonine Kinases
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Activin Receptors, Type I
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Receptor, Transforming Growth Factor-beta Type I
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Receptor, Transforming Growth Factor-beta Type II
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Tgfbr1 protein, rat
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Losartan