Aldosterone Modulates Cell Proliferation and Apoptosis in the Neonatal Rat Heart

In the present study, we investigated whether and how the mineralocorticoid receptor antagonist spironolactone affects cardiac growth and development through apoptosis and cell proliferation in the neonatal rat heart. Newborn rat pups were treated with spironolactone (200 mg/kg/d) for 7 days. The cell proliferation was studied by PCNA immunostaining. The treatment with spironolactone decreased proliferating myocytes by 32% (P<0.05), and reduced myocytes apoptosis by 29% (P<0.05). Immunoblot and immunohistochemistry for the expression of p38, p53, clusterin, TGF-beta2, and extracellular signal-regulated kinase were performed. In the spironolactone group, p38, p53, clusterin, and TGF-beta2 protein expression was significantly decreased (P<0.05). These results indicate that aldosterone inhibition in the developing rat heart induces cardiac growth impairment by decreasing proliferation and apoptosis of myocytes.

Endothelin A Receptor Blockade Influences Apoptosis and Cellular Proliferation in the Developing Rat Kidney

Endothelin systems are believed to play important roles in the emergence and maintenance of functions of various organs during perinatal development, including the kidney. The present study was designed to investigate the roles of endothelin systems on physiologic renal growth and development. Newborn rat pups were treated with either Bristol-Myers Squibb-182874 (30 mg/kg/day), a selective endothelin A receptor (ET(A)R) antagonist, or vehicle for 7 days. To identify cellular changes, kidneys were examined for apoptotic cells by terminal deoxynucleotide transferasemediated nick-end labeling stain and proliferating cell nuclear antigen (PCNA) by immunohistochemical (IHC) stain. To clarify the molecular control of these processes, immunoblots and reverse transcriptase-polymerase chain reaction for Clusterin, Bcl-2, Bcl-X(L), Bax, and p53 were performed. ETAR antagonist treatment resulted in reduced kidney weights, decreased PCNA-positive proliferating cells, and increased apoptotic cells. The protein expressions of renal Bcl-X(L) and Bax in the ETAR antagonist-treated group were significantly decreased, whereas the mRNA expressions of these genes were not changed. There were no significant differences in the expressions of Clusterin, Bcl-2, and p53. In conclusion, inhibition of endogenous endothelins impairs renal growth, in which decreased cellular proliferation, increased apoptosis and decreased expressions of renal Bcl-X(L) and Bax are possibly implicated.

Effect of angiotensin II inhibition on the epithelial to mesenchymal transition in developing rat kidney / 소아과

PURPOSE: To investigate the effects of angiotensin II inhibition on the epithelial to mesenchymal transition (EMT) in the developing kidney, we tested the expression of EMT markers and nestin in angiotensin converting enzyme (ACE) inhibitor-treated kidneys. METHODS: Newborn rat pups were treated with enalapril (30 mg/kg/d) or a vehicle for 7 days. Immunohistochemistry for the expression of alpha-smooth muscle actin (SMA), E-cadherin, vimentin, and nestin were performed. The number of positively-stained cells was determined under 100 magnification in 10 random fields. RESULTS: In the enalapril-treated group, alphaSMA-positive cells were strongly expressed in the dilated tubular epithelial cells. The number of alphaSMA-positive cells in the enalapril-treated group increased in both the renal cortex and medulla, compared to the control group (P<0.05). The expression of E-cadherin-positive cells was dramatically reduced in the cortical and medullary tubular epithelial cells in the enalapril-treated group (P<0.05). The number of vimentin- and nestin-positive cells in the cortex was not different in comparisons between the two groups; however, their expression increased in the medullary tubulointerstitial cells in the enalapril-treated group (P<0.05). CONCLUSION: Our results show that ACE inhibition in the developing kidney increases the renal EMT by up-regulatingalphaSMA and down-regulating E-cadherin. Enalapril treatment was associated with increased expression of vimentin and nestin in the renal medulla, suggesting that renal medullary changes during the EMT might be more prominent, and ACE inhibition might differentially modulate the expression of EMT markers in the developing rat kidney.