Anticholinesterase Activity of Aldicarb and Carbofuran in Neuron Cultures

Abstract

The anticholinesterase activity of the carbamate insecticides, carbofuran and aldicarb, was examined in primary cultures of chick embryo forebrain neurons. Both compounds inhibited acetylcholinesterase, with carbofuran being more potent than aldicarb by more than two orders of magnitude. Preincubation of carbofuran with hepatic S9, derived from rat or chick, decreased its anticholinesterase activity, with chick S9 exerting the greater deactivating effect. Conversely, preincubation of aldicarb with rat control S9 increased its anticholinesterase activity, while chick S9 had only a slight effect. Preincubation of the test compounds with S9 obtained from animals induced with phenobarbitone or 3-methylcholanthrene generally had a slightly deactivating effect, with the exception of aldicarb, where preincubation with induced rat hepatic S9 fractions slightly increased its potency as an anticholinesterase agent when compared to the effects of control S9. Preincubation of aldicarb and carbofuran with hepatic S9 fractions from both rat and chick altered their anticholinesterase activities, so that they were more predictive of their relative potential species toxicities in vivo. The relative toxicities of aldicarb and carbofuran, within a given species, however, were not as well predicted. This model may be of use in assessing the potential toxicities of carbamate pesticides with respect to species differences.