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Effect of pregnancy on the disposition of 2,2',3,5',6-pentachlorobiphenyl (PCB 95) atropisomers and their hydroxylated metabolites in female mice
Journal article   Open access   Peer reviewed

Effect of pregnancy on the disposition of 2,2',3,5',6-pentachlorobiphenyl (PCB 95) atropisomers and their hydroxylated metabolites in female mice

Izabela Kania-Korwel, Christopher D Barnhart, Pamela J Lein and Hans-Joachim Lehmler
Chemical research in toxicology, Vol.28(9), pp.1774-1783
09/21/2015
DOI: 10.1021/acs.chemrestox.5b00241
PMCID: PMC4579038
PMID: 26271003
url
https://doi.org/10.1021/acs.chemrestox.5b00241View
Published (Version of record) Open Access

Abstract

Chiral PCBs, such as PCB 95, are developmental neurotoxicants that undergo atropisomeric enrichment in nonpregnant adult mice. Because pregnancy is associated with changes in hepatic cytochrome P450 enzyme activity as well as lipid disposition and metabolism, this study investigates the effect of pregnancy on the maternal disposition of chiral PCBs. Female C57BL/6 mice (8 weeks old) were dosed daily beginning 2 weeks prior to conception and continuing throughout gestation and lactation (56 days total) with racemic PCB 95 (0, 0.1, 1.0, or 6.0 mg/kg body wt/day) in peanut butter. Levels and chiral signatures of PCB 95 and its hydroxylated metabolites (OH-PCBs) were determined in adipose, blood, brain, and liver. Tissue levels of PCB 95 increased 4- to 12-fold with increasing dose, with considerable enrichment of the second eluting atropisomer in all tissues (EF range 0.11 to 0.26). OH-PCBs displayed atropisomeric enrichment in blood and liver but were not detected in adipose and brain. Levels of PCB 95 and its metabolites were 2- to 11-fold lower in pregnant dams relative to those previously reported in nonpregnant age-matched female mice; however, PCB 95 and OH-PCB profiles and chiral signatures were similar between both studies. In contrast, human brain samples contained racemic PCB 95 residues (EF = 0.50). These results demonstrate that changes in cytochrome P450 enzyme activity and lipid disposition during pregnancy reduce the PCB body burden in dams but do not affect metabolite profiles or chiral signatures. The differences in chiral signatures between mice and humans suggest species-specific differences in atropisomeric disposition, the toxicological significance of which remains to be determined.
Brain - metabolism Dose-Response Relationship, Drug Pregnancy Animals Hydroxylation Humans Mice, Inbred C57BL Female Polychlorinated Biphenyls - pharmacokinetics Mice ISRP Project 3 2015-2020 ISRP Project 5 2015-2020 Synthesis Core

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