Archives of Toxicology 1980-10-01

Repeated small doses of a neurotoxic organophosphate. Monitoring of neurotoxic esterase in brain and spinal cord.

M Lotti, M K Johnson

Index: Arch. Toxicol. 45(4) , 263-71, (1980)

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Abstract

The effects of small repeated oral doses of mono-2-cresyl diphenyl phosphate (MOCP, 2.5 mg/kg/day) on hen brain and spinal cord neurotoxic esterase (NTE) were measured. The enzyme levels were depressed to about 40% and 55% of normal respectively and maintained at that level for 8 weeks. No clinical and only doubtful histological signs of neuropathy were detected. Neuropathy could be precipitated by depressing the level to < 20% either with a single high dose (50 mg/kg), or by an increase of the repeated dose level to 5 mg/kg/day. There was no correlation between inhibition of NTE in the nervous tissue and the "NTE-like" activity in lymphocytes. "NTE-like" activity in spleen was consistently inhibited but to a lesser extent than that in the brain or spinal cord. Brain AChE and BuChE were not affected.