Absence of acrylamide-induced genotoxicity in CYP2E1-null mice: Evidence consistent with a glycidamide-mediated effect
ABSTRACT Acrylamide, an animal carcinogen and germ cell mutagen present at low (ppm) levels in heated carbohydrate-containing foodstuffs, is oxidized by cytochrome P4502E1 (CYP2E1) to the epoxide glycidamide, which is believed to be responsible for the mutagenic and carcinogenic activity of acrylamide. We recently reported a comparison of the effects of acrylamide on the genetic integrity of germ cells of male wild-type and CYP2E1-null mice [B.I. Ghanayem, K.L. Witt, L. El-Hadri, U. Hoffler, G.E. Kissling, M.D. Shelby, J.B. Bishop, Comparison of germ-cell mutagenicity in male CYP2E1-null and wild-type mice treated with acrylamide: evidence supporting a glycidamide-mediated effect, Biol. Reprod. 72 (2005) 157-163]. In those experiments, dose-related increases in dominant lethal mutations were detected in uterine contents of female mice mated to acrylamide-treated wild-type males but not CYP2E1-null males, clearly implicating CYP2E1-mediated formation of glycidamide in the induction of genetic damage in male germ cells. We hypothesized that acrylamide-induced somatic cell damage is also caused by glycidamide. Therefore, to examine this hypothesis, female wild-type and CYP2E1-null mice were administered acrylamide (0, 25, 50mg/kg) by intraperitoneal injection once daily for 5 consecutive days. Twenty-four hours after the final treatment, blood and tissue samples were collected. Erythrocyte micronucleus frequencies were determined using flow cytometry and DNA damage was assessed in leukocytes, liver, and lung using the alkaline (pH>13) single cell gel electrophoresis (Comet) assay. Results were consistent with the earlier observations in male germ cells: significant dose-related increases in micronucleated erythrocytes and DNA damage in somatic cells were induced in acrylamide-treated wild-type but not in the CYP2E1-null mice. These results support the hypothesis that genetic damage in somatic and germ cells of mice-treated with acrylamide is dependent upon metabolism of the parent compound by CYP2E1. This dependency on metabolism has implications for the assessment of human risks resulting from occupational or dietary exposure to acrylamide. CYP2E1 polymorphisms and variability in CYP2E1 activity associated with, for example, diabetes, obesity, starvation, and alcohol consumption, may result in altered metabolic efficiencies leading to differential susceptibilities to acrylamide toxicities in humans.
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ABSTRACT: Background: Acrylamide (AA) is an important industrial chemical primarily. AA is also found in carbohydrate-rich foods that are prepared at high temperatures, such as French fries and potato chips. It is demonstrated that AA is a carcinogen and reproductive toxin and has ability to induce sperm damage. Objective: The aim of this study was to observe the effects of AA on sperm parameters and evaluation of sperm chromatin quality and testosterone hormone in mice. Materials and Methods: Totally, 16 adult male mice were divided into two groups. Mice of group A fed on basal diet; group B received basal diet and AA (10 mg/kg, water solution) for 35 days. The right cauda epididymis was incised and then placed in Ham’s F10 culture media at 37oC for 15 min. Released spermatozoa were used to analyze count, motility, morphology and viability. To determine the sperm DNA integrity and chromatin condensation, the cytochemical techniques including Aniline blue, Acridine orange and Chromomycin A3 staining were used. Results: AA-treated mice had poor parameters in comparison with control animals. In sperm chromatin assessments, except TB (p=0.16), significant differences were found in all of the tests between two groups. It was also seen a significant decrease in concentration of blood testosterone in AA-treated animals when compared to controls (p<0.001). Conclusion: According to our results, AA can affect sperm parameters as well as sperm chromatin condensation and DNA integrity in mice. These abnormalities may be related to the reduction in blood testosterone.Iranian Journal of Reproductive Medicine 05/2014; 12(5):335-42. · 0.19 Impact Factor
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ABSTRACT: Acrylamide is formed in heat processing of many common foods. According to animal cancer tests acrylamide is a carcinogen. To estimate the cancer risk from exposure via food, the response at high doses in the cancer tests with rats has to be extrapolated to the exposure levels in humans. Acrylamide is biotransformed to the epoxide glycidamide, which is assumed to be the cancer-risk increasing agent. Therefore in vivo doses of both acrylamide and glycidamide should be measured in rats and humans and related to the acrylamide intake. In vivo doses (area under the time-concentration curve, AUC) of reactive compounds can be determined from measured reaction products, adducts, to hemoglobin (Hb). A study in mice showed that the food matrix does not have an influence on the absorbed amount of acrylamide from food. There was a linear dose-response of Hb-adduct levels from acrylamide and glycidamide.
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ABSTRACT: Acrylamide is a toxin that humans are readily exposed to due to its formation in many carbohydrate rich foods cooked at high temperatures. Acrylamide is carcinogenic, neurotoxic and causes reproductive toxicity when high levels of exposure are reached in mice and rats. Acrylamide induced effects on fertility occur predominantly in males. Acrylamide exerts its reproductive toxicity via its metabolite glycidamide, a product which is only formed via the cytochrome P450 detoxifying enzyme CYP2E1. Glycidamide is highly reactive and forms adducts with DNA. Chronic low dose acrylamide exposure in mice relevant to human exposure levels results in significantly increased levels of DNA damage in terms of glycidamide adducts in spermatocytes, the specific germ cell stage where Cyp2e1 is expressed. Since cells in the later stages of spermatogenesis are unable to undergo DNA repair, and this level of acrylamide exposure causes no reduction in fertility, there is potential for this damage to persist until sperm maturation and fertilisation. Cyp2e1 is also present within epididymal cells, allowing for transiting spermatozoa to be exposed to glycidamide. This could have consequences for future generations in terms of predisposition to diseases such as cancer, with growing indications that paternal DNA damage can be propagated across multiple generations. Since glycidamide is the major contributor to DNA damage, a mechanism for preventing these effects is inhibiting the function of Cyp2e1. Resveratrol is an example of an inhibitor of Cyp2e1 which has shown success in reducing damage caused by acrylamide treatment in mice. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 04/2015; 777. DOI:10.1016/j.mrfmmm.2015.04.008 · 4.44 Impact Factor