Dataset Information

Comparison of Toxicity and Recovery in the Duodenum of B6C3F1 Mice Following Treatment with Intestinal Carcinogens Captan, Folpet, and Hexavalent Chromium.

ABSTRACT: High concentrations of hexavalent chromium (Cr(VI)), captan, and folpet induce duodenal tumors in mice. Using standardized tissue collection procedures and diagnostic criteria, we compared the duodenal histopathology in B6C3F1 mice following exposure to these 3 carcinogens to determine whether they share similar histopathological characteristics. B6C3F1 mice ( n = 20 per group) were exposed to 180 ppm Cr(VI) in drinking water, 12,000 ppm captan in feed, or 16,000 ppm folpet in feed for 28 days. After 28 days of exposure, villous enterocyte hypertrophy and mild crypt epithelial hyperplasia were observed in all exposed mice. In a subset of mice allowed to recover for 28 days, duodenal samples were generally indistinguishable from those of unexposed mice. Changes in the villi and lack of observable damage to the crypt compartment suggest that toxicity was mediated in the villi, which is consistent with earlier studies on each chemical. These findings indicate that structurally diverse agents can induce similar (and reversible) phenotypic changes in the duodenum. These intestinal carcinogens likely converge on common pathways involving irritation and wounding of the villi leading to crypt regenerative hyperplasia that, under protracted high-dose exposure scenarios, increases the risk of spontaneous mutation and tumorigenesis.

SUBMITTER: Thompson CM

PROVIDER: S-EPMC5761716 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Comparison of Toxicity and Recovery in the Duodenum of B6C3F1 Mice Following Treatment with Intestinal Carcinogens Captan, Folpet, and Hexavalent Chromium.

Thompson Chad M CM Wolf Jeffrey C JC McCoy Alene A Suh Mina M Proctor Deborah M DM Kirman Christopher R CR Haws Laurie C LC Harris Mark A MA

Toxicologic pathology 20171121 8

High concentrations of hexavalent chromium (Cr(VI)), captan, and folpet induce duodenal tumors in mice. Using standardized tissue collection procedures and diagnostic criteria, we compared the duodenal histopathology in B6C3F1 mice following exposure to these 3 carcinogens to determine whether they share similar histopathological characteristics. B6C3F1 mice ( n = 20 per group) were exposed to 180 ppm Cr(VI) in drinking water, 12,000 ppm captan in feed, or 16,000 ppm folpet in feed for 28 days. ...[more]

PMID: 29161989

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Project description:Significant occupational and environmental exposures to hexavalent chromium, a metal with broad toxicity potential in humans, have been reported. In order to understand the mechanisms of dermal toxicity induced by hexavalent chromium, global gene expression profiling of human dermal fibroblasts exposed to a toxic concentration of potassium dichromate was performed. Microarray analysis of the gene expression profile in the fibroblasts treated with potassium dichromate identified significant differential expression of approximately 1,200 transcripts compared with the control cells. Hierarchical cluster analysis of the gene expression profile demonstrated a clear separation of the treated cells from the control group of cells. Functional categorization of the differentially expressed genes identified the enrichment of genes involved in several cellular processes, including apoptosis and oxidative stress, in the fibroblasts exposed to hexavalent chromium. Induction of apoptosis and generation of hydroxyl radicals indicative of oxidative stress in the dermal fibroblasts in response to their exposure to hexavalent chromium were independently confirmed by TUNEL assay and electron spin resonance (ESR) analysis, respectively. The potassium dichromate-induced cytotoxicity, differential gene expression, apoptosis, and oxidative stress were significantly blocked by the addition of ferrous sulfate, an agent known for its ability to reduce hexavalent chromium to the insoluble and therefore impermeable trivalent form, to the cell culture medium. Taken together, our data provide insights into the potential mechanisms underlying the dermal toxicity of hexavalent chromium and suggest a definite role for apoptosis and oxidative stress in Cr(VI)-induced cytotoxicity in human dermal fibroblasts. 16 samples were analyzed in this experiment. Exponentially growing human dermal fibroblasts (3x105 cells) were cultured in T25 cell culture flasks. When the cells were approximately 70% confluent, hexavalent potassium dichromate (5µM) was added to the medium with or without 40µM ferrous sulfate. Following 16 hours of culturing at 37oC, total RNA was isolated for gene expression studies. Details of the samples are: Control 4 Samples: Cr(0)-1, Cr(0)-2, Cr(0)-3, Cr(0)-4 Cr 5 µM 4 Samples: Cr(5)-5, Cr(5)-6, Cr(5)-7, Cr(5)-8 FeSO4 40 µM 4 Samples: Fe(40)-9, Fe(40)-10, Fe(40)-11, Fe(40)-12 Cr 5 µM + FeSO4 40 µM 4 Samples: Cr(5)+Fe(40)-13,Cr(5)+Fe(40)-14, Cr(5)+Fe(40)-15, Cr(5)+Fe(40)-16

Project description:This study was conducted to investigate the molecular mechanisms of selenium (Se) antagonism of hexavalent chromium (Cr6+)-induced toxicity. Potassium dichromate (K2Cr2O7) and selenium-enriched yeast (SeY) were used to construct the single Cr6+ and combined Se/Cr6+ exposure broiler models, and then the broilers were randomly divided into four groups (C group, Se group, Se/Cr6+ group, and Cr6+ group). After a 42-day experiment, the spleen tissues of broilers were excised and weighted. The antagonistic mechanisms of Se and Cr6+ were evaluated using histopathological assessment, serum biochemical tests, oxidative stress kits, ELISA, qPCR, and Western blotting. On the whole, there were no significant changes between the C and Se groups. The spleen organ index in the Cr6+ group was significantly decreased, but SeY increased spleen organ index to a certain extent. The levels of SOD and GSH were reduced, and the MDA content was elevated by Cr6+; however, these changes were mitigated by Se/Cr6+ exposure. Importantly, Cr6+ exposure induced a series of histopathological injuries in broiler spleen tissues, while these symptoms were significantly relieved in the Se/Cr6+group. Furthermore, Cr6+ significantly decreased the levels of T-globulin, IgA, IgM, and IgG in serum. Contrarily, dramatically more T-globulin IgA, IgM, and IgG were found in the Se/Cr6+group than in the Cr6+ group. Revealed by the results of qPCR and WB, the expressions of NF-κB, IκBα, and p-IκBα were upregulated in Cr6+ groups, while they were downregulated in Se/Cr6+ group compared to that in Cr6+ group. Besides IFN-γ and IL-2, the expressions of pro-inflammatory cytokines were significantly increased by Cr6+ exposure, but the SeY supplement relived the expression levels mediated by Cr6+ exposure. In conclusion, our findings suggest SeY has biological activity that can protect broiler spleens from immunosuppression and inflammation induced by Cr6+, and we speculate that the NF-κB signaling pathway is one of its mechanisms.

Dataset Information

Comparison of Toxicity and Recovery in the Duodenum of B6C3F1 Mice Following Treatment with Intestinal Carcinogens Captan, Folpet, and Hexavalent Chromium.

Publications

Comparison of Toxicity and Recovery in the Duodenum of B6C3F1 Mice Following Treatment with Intestinal Carcinogens Captan, Folpet, and Hexavalent Chromium.

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