Acute effects of the organophosphate paraoxon on schedule-controlled behavior and esterase activity in rats: dose-response relationships.
The effects of acute intraperitoneal administration of paraoxon on behavioral and biochemical parameters were studied in male rats. Rats were trained to press a lever under an FR10 schedule of reinforcement. Rats were injected with 3 sublethal doses of paraoxon (0.5, 0.75, and 1.0 mg/kg) and performance was monitored for four days after exposure. Response rates were depressed significantly for days 1 and 2 with 0.75 and 1.0 mg/kg, but not 0.5 mg/kg, even though there was inhibition of brain and plasma cholinesterases at all doses. Performance recovered prior to brain AChE recovery. There was no clear-cut threshold of brain AChE inhibition required to yield performance deficits, nor was there a direct correlation between significant inhibition in peripheral enzymes which could serve as markers (plasma aliesterases, butyrylcholinesterase, non-iso-OMPA-sensitive cholinesterase, and hepatic aliesterases) and performance deficits, suggesting that other noncholinergic targets may play a role in OP-induced behavioral deficits.
Carr
R L
RL
College of Veterinary Medicine, Mississippi State University, MS 39762.
Chambers
J E
JE
D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D004950:Esterases / Q000378:metabolism*; D008297:Male; D010261:Paraoxon / Q000008:administration & dosage / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D012055:Reinforcement Schedule
D004950:Esterases; D000110:Acetylcholinesterase; D010261:Paraoxon