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Main Title Dose-Related Inhibition of Brain and Plasma Cholinesterase in Neonatal and Adult Rats Following Sublethal Organophosphate Exposures.
Author Pope, C. N. ;
CORP Author Northeast Louisiana Univ., Monroe. School of Pharmacy.;Health Effects Research Lab., Research Triangle Park, NC.
Publisher c1992
Year Published 1992
Report Number EPA/600/J-92/274;
Stock Number PB92-209360
Additional Subjects Cholinesterase inhibitors ; Brain ; Blood ; Organophosphate insecticides ; Dursban ; Regression analysis ; Methyl parathion ; Parathion ; In vivo analysis ; Rats ; Newborn animals ; Reprints ;
Library Call Number Additional Info Location Last
NTIS  PB92-209360 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 11p
Developing mammals are markedly more sensitive to acute toxicity from exposure to a variety of organophosphorus (OP) pesticides. The present study examined dose-related inhibition of both brain and plasma cholinesterase activity in neonatal and adult rats exposed to sublethal doses of one of three common OP pesticides, methyl parathion, parathion and chlorpyrifos. Effective dose 50 (i.e., ED50 or dose which would inhibit 50% of the cholinesterase activity) values were determined and then correlated with an indicator of acute toxicity, the maximal tolerated dose (MTD). It was found that ED50 estimates for both brain and plasma cholinesterase correlated highly (r = 0.932-0.992) with previously derived MTD values. In no case was there a significant difference between in vivo brain and plasma cholinesterase sensitivity as expressed by ED50 values. The correlation between the extent of brain and plasma cholinesterase inhibition across doses in neonatal rats was high (r = 0.962-0.975) but lower in adults (r = 0.700-0.943). The results suggest that in vivo inhibitory potency of the three OPs towards either brain or plasma ChE activity is highly correlated with sensitivity to acute toxicity in both neonatal and adult rats. Additionally, under defined experimental conditions, plasma ChE inhibition may be a useful quantitative index for the degree of brain cholinesterase inhibition following OP exposures. (Copyright (c) 1992 Elsevier Scientific Publishers Ireland Ltd.)