Mammalian targets, pyrethroid insecticides

Pyrethroid insecticides (deltamethrin, NRDC 157, cismethrin), DDT analogs ( p,j> -DDT, (>,j> -DDT, methoxychlor, EDO), and a DDT-pyrethroid hybrid compound (GH401) enhanced veratridine-dependent sodium uptake by mouse brain synaptosomes The effectiveness of these compounds in the sodium uptake assay was in good agreement with their acute mammalian toxicities. , -DDT also enhanced veratridine-dependent sodium uptake by fish brain synaptosomes These findings demonstrate the utility of ion flux assays to study interactions of insecticides with sodium channels in the central nervous system and to explore species differences in insecticide target site sensitivity ... 

The establishment of a common mechanism of mammalian toxicity for the pyrethroids is not a straight forward process, as it was for the organophosphorus and carbamate insecticides, due to the occurrence of multiple potential target sites and the varied action of pyrethroids at these sites as reviewed above. In view of... 

The data presented above show clearly that GABA receptors of mammalian brain are targets for the toxic action of cyclodiene, yBHC and pyrethroids. Although, the binding and flux assays, used so sucessfully to study interactions of these insecticides with mammalian brain, have had limited success when applied to insect tissues, there is ample evidence to suggest that GABA receptors of insects are targets for AVM (7, 21) cyclodienes and pyrethroids (17, 22). 

In fact, only two new classes of insecticides have been developed for commercial use in the last 30 years. Both the synthetic pyrethroids and the avermectins have excellent mammalian saftety. However, both are encumbered by previously evolved target site resistance, selected by over-use of DDT and cyclodiene insecticides, respectively. Thus, the remaining importance of the OPs and the carbamates is obvious. 

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