Developmental toxicity of desbromoleptophos in chicks: Enzyme inhibition, malformations and functional deficits

The relationship among inhibition of acetylcholinesterase (AChE), inhibition of neuropathy target enzyme (NTE), and developmental toxicity of the organophosphorus ester desbromoleptophos (DBL) was evaluated in chicks exposed on day 3 or day 15 of incubation or 10 days posthatching. DBL induced prolonged inhibition of AChE and NTE when administered either early or late in incubation, structural malformations if administered before organogenesis, posthatching paresis if administered after organogenesis, and delayed deficits of gait if administered after hatching. The posthatching paresis and abnormal gait are not determined solely by either AChE inhibition or NTE inhibition, since they occur in the absence of the latter and are not invariably seen in the presence of the former (Toxicology 49: 253-261; 1988).