Brain cholinesterase activity of bobwhite acutely exposed to chlorpyrifos

Abstract

Northern bobwhite, Colinus virginianus, were orally dosed with the organophosphorus insecticide chlorpyrifos to examine effects on brain chohnesterase (ChE) activity. Two‐week‐old quail were acutely exposed and euthanized at selected times following gavage‐dosing, ranging from I to 120 h later. The ChE activity was determined in treated birds and compared to concurrently tested control (corn oil) birds. It was found that a lag time of 2 to 4 h following exposure was necessary to detect significant ChE depression caused by chlorpyrifos. The lowest dose that produced ChE depression in these tests was between —30 and 50 mg chlorpyrifos/kg body weight, with some mortality occurring at the high end of that range. Depression typically persisted for at least 24 h.

Acute Toxicity and Cholinesterase Inhibition in Chicks Dosed Orally with Organophosphate Insecticides

“…The most important diagnostic or biomarker endpoint of OP exposure and poisoning is decreased ChE activity in the blood (erythrocytes, plasma or serum) and other tissues, brain in particular (3)(4)(5)(6)(7)(8). Birds have no ChE activity in erythrocytes; therefore, the extent of their exposure to and/or OP poisoning is based on ChE activity in plasma and nervous tissue (3,(9)(10)(11).…”

“…The toxicity of OP insecticides in birds is generally associated with lower plasma or brain ChE activities (9,(12)(13)(14). Decreases in ChE activity to 50 % or less of the normal is accepted as confirmation of exposure or diagnosis of acute poisoning with these insecticides (3,15,16).…”

“…Decreases in ChE activity to 50 % or less of the normal is accepted as confirmation of exposure or diagnosis of acute poisoning with these insecticides (3,15,16). Various reports indicate close association between reduced blood or brain ChE activity and acute toxicosis induced by doses close to or higher than the median lethal doses (LD 50 ) of OP insecticides in rodents and birds (3,9,(16)(17)(18)(19).…”

Ecological Risk Assessment for Chlorpyrifos in Terrestrial and Aquatic Systems in the United States

“…Chlorpyrifos inhibits acetylcholinesterase activity causing acetylcholine to accumulate at nerve terminals and neuromuscular junctions, which leads to cholinergic overstimulation (Testai et al 2010 ). In birds, CPY poisoning can be detected biochemically as reduced cholinesterase activity in plasma and brain tissues (Cairns et al 1991 ;Parsons et al 2000 ;Timchalk 2010 ). A gavage study with northern bobwhite ( C. virginianus ) found reduced brain cholinesterase activity at concentrations of 47 mg ai kg −1 bwt of CPY and greater (Cairns et al 1991 ).…”

“…In birds, CPY poisoning can be detected biochemically as reduced cholinesterase activity in plasma and brain tissues (Cairns et al 1991 ;Parsons et al 2000 ;Timchalk 2010 ). A gavage study with northern bobwhite ( C. virginianus ) found reduced brain cholinesterase activity at concentrations of 47 mg ai kg −1 bwt of CPY and greater (Cairns et al 1991 ). Cholinesterase activity remained inhibited for at least 24-48 h thereafter.…”