Cellular and molecular fingerprinting of the glomerulus as a critical site of nephrotoxic injury by benzo(a)pyrene /
The present studies were conducted to assess the nephrotoxicity of benzo(a)pyrene (BaP) in vivo and begin to define a plausible mechanism of toxicity using an in vitro model. Ten week-old female Sprague-Dawley rats were challenged with BaP (10 mg/kg, i.p.) for up to 16 weeks. Kidney morphology, pr...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
2001.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=728908711&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The present studies were conducted to assess the nephrotoxicity of benzo(a)pyrene (BaP) in vivo and begin to define a plausible mechanism of toxicity using an in vitro model. Ten week-old female Sprague-Dawley rats were challenged with BaP (10 mg/kg, i.p.) for up to 16 weeks. Kidney morphology, protein expression and function were evaluated. Morphometric analysis demonstrated that cellularity of the glomerulus was significantly higher in BaP-treated rats relative to control counterparts. At the ultrastructural level, podocyte injury was present in BaP exposed rats. α-smooth muscle actin expression, associated with mesangial cell injury, was increased in glomeruli at 16 weeks of BaP challenge. Meanwhile, proliferating cell nuclear antigen expression, an index for actively proliferating cells, was decreased. Clinical chemistries showed that total protein and albumin levels in the urine were significantly higher in BaP challenged rats at 16 weeks. These data showed that BaP induces glomerular hypercellularity, injures GMCs and podocytes, and induces glomerular dysfunction. Given that an adaptive response of glomerular cells (GCs) in vitro to BaP injury involves a reduction of the number of cells with mesenchymal characteristics to a predominance of epithelial cell phenotypes, in vitro studies were conducted to examine critical glomerular mesenchymal/epithelial interactions. GC, single cell clone (SCC) 1 (mesenchymal) and SCC 4E (epithelial) cultures were challenged with BaP (3.0 []M) for 24 hours. Protein expression, proliferation rates and gene expression were examined to characterize GCs involved in the adaptive response to BaP injury. Immunofluorescence experiments demonstrated that BaP challenged cultures were dominated by podocytic cells and DNA synthesis studies illustrated that BaP significantly inhibited GMC proliferation, but unaffected GVECs. Co-cultured experiments demonstrated that GMCs inhibited GVEC proliferation. CYP1A1 and CYP1B1 gene expression and associated activities in mesangial and podocytic clones after BaP challenge identified oxidative metabolism as a critical step in mesangial cell cytotoxicity. Candidate mesenchymal-derived inhibitors of GVEC proliferation, transforming growth factor beta 1, prostaglandin E₂, and nitric oxide, did not inhibit SCC 4E proliferation rates. These data showed that disruption of GMCs by BaP might effect podocytic function. Collectively, these studies demonstrate that the glomerulus is a critical site of BaP toxicity. |
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| Item Description: | Vita. "Major Subject: Toxicology". |
| Physical Description: | xiii, 132 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 104-130). |