title: Inhibition and recovery of maternal and foetal cholinesterase enzymes following fenitrothion administration in CD rats.
abstract: The purpose of this study was to characterize tissue esterase activity and blood fenitrothion concentrations in the rat dam and foetus following in-utero exposure to the organophosphate insecticide fenitrothion. Time-mated, 8-week-old rats were gavaged on gestation day 19 with 0, 5, or 25 mg fenitrothion kg-1. Fenitrothion was absorbed rapidly from the gastrointestinal tract, with peak maternal and foetal blood levels observed 0.5-1.0 h after dosing. Fenitrothion concentrations in maternal and foetal blood were virtually identical and demonstrated a non-linear dose-response relationship. Acetylcholinesterase and carboxylesterase activities in maternal liver and blood and in foetal liver and brain decreased within 30-60 min of fenitrothion exposure. Esterase inhibition occurred at a fenitrothion dose (5 mg kg-1) that has not been previously associated with reproductive toxicity, suggesting that esterase inhibition should be considered as the critical effect in risk assessments for this pesticide.
authors.affiliation: CIIT Centers for Health Research, Research Triangle Park, NC 27709, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Sochaski
authors.forename: B M
authors.initials: BM
authors.lastname: McManus
authors.forename: M F
authors.initials: MF
authors.lastname: Struve
authors.forename: D G
authors.initials: DG
authors.lastname: Wallace
authors.forename: D C
authors.initials: DC
authors.lastname: Dorman
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D002802:Cholinesterases / Q000378:metabolism*; D005260:Female; D005278:Fenitrothion / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology*; D005333:Fetus / Q000187:drug effects* / Q000201:enzymology*; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D011247:Pregnancy; D051381:Rats
chemical_list: D002800:Cholinesterase Inhibitors; D002802:Cholinesterases; D005278:Fenitrothion