Inhibition and recovery of maternal and foetal cholinesterase enzymes following fenitrothion administration in CD rats.
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.
Sochaski
M A
MA
CIIT Centers for Health Research, Research Triangle Park, NC 27709, USA.
McManus
B M
BM
Struve
M F
MF
Wallace
D G
DG
Dorman
D C
DC
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
D002800:Cholinesterase Inhibitors; D002802:Cholinesterases; D005278:Fenitrothion