Carbamate poisoning. Effects of selected carbamate pesticides on plasma enzymes and brain esterases of Japanese quail (Coturnix coturnix japonica)

Lethal and sublethal doses (0.33 or 0.5 X LD sub(50), LD sub(50), and 2 or 3 X LD sub(50)) of aldicarb, methiocarb, oxamyl, pirimicarb, and thiofanox were administered to Japanese quail. Lethal doses of carbamates gave >64% inhibition of plasma AChE and >75% inhibition of plasma ChE. Plasma esterase activities at 24 h after dosing generally returned to control levels or above. Lethal doses of carbamates produced similar to 40-60% inhibition of brain AChE although the maximal inhibition for pirimicarb treatment was 97%. A dose-response relationship for brain AChE was only found in lethally dosed quail given oxamyl and pirimicarb. No birds surviving the carbamate treatments at 24 h showed significant inhibition of brain AChE, and birds surviving doses of aldicarb, methiocarb, and pirimicarb showed elevated esterase levels. After 24 h, increases in plasma GOT levels were observed in survivors from all the carbamate treatments. Elevation in plasma GDH levels were observed only in survivors from the aldicarb treatments. The changes resulting from sublethal carbamate dosing are discussed and compared with the responses obtained on dosing organophosphate pesticides to Japanese quail.