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Differential metabolism of inorganic arsenic in mice from genetically diverse Collaborative Cross strains.

ABSTRACT: Mice have been frequently used to study the adverse effects of inorganic arsenic (iAs) exposure in laboratory settings. Like humans, mice metabolize iAs to monomethyl-As (MAs) and dimethyl-As (DMAs) metabolites. However, mice metabolize iAs more efficiently than humans, which may explain why some of the effects of iAs reported in humans have been difficult to reproduce in mice. In the present study, we searched for mouse strains in which iAs metabolism resembles that in humans. We examined iAs metabolism in male mice from 12 genetically diverse Collaborative Cross (CC) strains that were exposed to arsenite in drinking water (0.1 or 50 ppm) for 2 weeks. Concentrations of iAs and its metabolites were measured in urine and livers. Significant differences in total As concentration and in proportions of total As represented by iAs, MAs, and DMAs were observed between the strains. These differences were more pronounced in livers, particularly in mice exposed to 50 ppm iAs. In livers, large variations among the strains were found in percentage of iAs (15-48%), MAs (11-29%), and DMAs (29-66%). In contrast, DMAs represented 96-99% of total As in urine in all strains regardless of exposure. Notably, the percentages of As species in urine did not correlate with total As concentration in liver, suggesting that the urinary profiles were not representative of the internal exposure. In livers of mice exposed to 50 ppm, but not to 0.1 ppm iAs, As3mt expression correlated with percent of iAs and DMAs. No correlations were found between As3mt expression and the proportions of As species in urine regardless of exposure level. Although we did not find yet a CC strain in which proportions of As species in urine would match those reported in humans (typically 10-30% iAs, 10-20% MAs, 60-70% DMAs), CC strains characterized by low %DMAs in livers after exposure to 50 ppm iAs (suggesting inefficient iAs methylation) could be better models for studies aiming to reproduce effects of iAs described in humans.

SUBMITTER: Styblo M

PROVIDER: S-EPMC7244219 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Differential metabolism of inorganic arsenic in mice from genetically diverse Collaborative Cross strains.

Stýblo Miroslav M Douillet Christelle C Bangma Jacqueline J Eaves Lauren A LA de Villena Fernando Pardo-Manuel FP Fry Rebecca R

Archives of toxicology 20190906 10

Mice have been frequently used to study the adverse effects of inorganic arsenic (iAs) exposure in laboratory settings. Like humans, mice metabolize iAs to monomethyl-As (MAs) and dimethyl-As (DMAs) metabolites. However, mice metabolize iAs more efficiently than humans, which may explain why some of the effects of iAs reported in humans have been difficult to reproduce in mice. In the present study, we searched for mouse strains in which iAs metabolism resembles that in humans. We examined iAs m ...[more]

PMID: 31493028

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Project description:Identification of molecular determinants of the inter-individual and sex variability in the development of nonalcoholic fatty liver disease (NAFLD) is of great importance. Next-generation sequencing (NGS) derived transcriptome profiling (RNA-seq) is a powerful technique to investigate gene transcripts and gene variants for the systems-based analysis of molecular and cellular pathways. The goal of this study was to determine transcriptomic profiles in the livers of male and female Collaborative Cross (CC) mice fed a high-fat and high-sucrose (HF/HS) diet or a control diet for 12 weeks and to identify inter-individual- and sex-specific gene expression differences during the development of NAFLD. Liver mRNA profiles of 10 CC mouse strains (CC003/Unc, CC011/Unc, CC013/GeniUnc, CC019/TauUnc, CC032/GeniUnc, CC040/TauUnc, CC041/TauUnc, CC042/GeniUnc, CC043/GeniUnc, and CC060/Unc) fed an HF/HS diet were generated by deep sequencing, in triplicate, using Illumina NextSeq 500 NGS system. The sequence reads that passed quality filters were analyzed at the transcript level using TopHat followed by Cufflinks. The total number of differentially expressed genes identified by RNA-seq varied between sexes and individual mouse strains and correlated with the severity of liver steatosis. Pathway analysis of differentially expressed genes showed dysregulation of genes involved in lipid metabolism, cell proliferation and death, inflammation, and fibrogenesis pathways in the livers of males and females CC mice. The RNA-seq data were validated and confirmed by qRT-PCR analysis of 27 selected genes associated with lipid metabolism and fibrogenesis using TaqMan assays. Our results show that RNA-seq based transcriptome analysis offers a comprehensive, quantitative, and qualitative evaluation of whole-genome expression that can be used for the identification of unique genes associated with the inter-individual and sex differences in susceptibility to NAFLD at the population level.

Project description:RationaleFew effective treatments exist for cocaine use disorders due to gaps in knowledge about its complex etiology. Genetically defined animal models provide a useful tool for advancing our understanding of the biological and genetic underpinnings of addiction-related behavior and evaluating potential treatments. However, many attempts at developing mouse models of behavioral disorders were based on overly simplified single gene perturbations, often leading to inconsistent and misleading results in pre-clinical pharmacology studies. A genetically complex mouse model may better reflect disease-related behaviors.ObjectivesScreening defined, yet genetically complex, intercrosses of the Collaborative Cross (CC) mice revealed two lines, RIX04/17 and RIX41/51, with extreme high and low behavioral responses to cocaine. We characterized these lines as well as their CC parents, CC004/TauUnc and CC041/TauUnc, to evaluate their utility as novel model systems for studying the biological and genetic mechanisms underlying behavioral responses to cocaine.MethodsBehavioral responses to acute (initial locomotor sensitivity) and repeated (behavioral sensitization, conditioned place preference, intravenous self-administration) exposures to cocaine were assessed. We also examined the monoaminergic system (striatal tissue content and in vivo fast scan cyclic voltammetry), HPA axis reactivity, and circadian rhythms as potential mechanisms for the divergent phenotypic behaviors observed in the two strains, as these systems have a previously known role in mediating addiction-related behaviors.ResultsRIX04/17 and 41/51 show strikingly divergent initial locomotor sensitivity to cocaine with RIX04/17 exhibiting very high and RIX41/51 almost no response. The lines also differ in the emergence of behavioral sensitization with RIX41/51 requiring more exposures to exhibit a sensitized response. Both lines show conditioned place preference for cocaine. We determined that the cocaine sensitivity phenotype in each RIX line was largely driven by the genetic influence of one CC parental strain, CC004/TauUnc and CC041/TauUnc. CC004 demonstrates active operant cocaine self-administration and CC041 is unable to acquire under the same testing conditions, a deficit which is specific to cocaine as both strains show operant response for a natural food reward. Examination of potential mechanisms driving differential responses to cocaine show strain differences in molecular and behavioral circadian rhythms. Additionally, while there is no difference in striatal dopamine tissue content or dynamics, there are selective differences in striatal norepinephrine and serotonergic tissue content.ConclusionsThese CC strains offer a complex polygenic model system to study underlying mechanisms of cocaine response. We propose that CC041/TauUnc and CC004/TauUnc will be useful for studying genetic and biological mechanisms underlying resistance or vulnerability to the stimulatory and reinforcing effects of cocaine.

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Differential metabolism of inorganic arsenic in mice from genetically diverse Collaborative Cross strains.

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Differential metabolism of inorganic arsenic in mice from genetically diverse Collaborative Cross strains.

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