Mouse brain, effects pyrethroids

Eriksson P, Nordbrg A (1990) Effects of two pyrethroids, bioallethrin and deltamethrin, on subpopulations of muscarinic and nicotinic receptors in the neonatal mouse brain. Toxicol Appl Pharmacol 102 456-463... 

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 ... 

In this paper, we report that DDT and its analogs, as well as pyrethroids, enhance veratridine-dependent sodium uptake in mouse brain synaptosomes. We also demonstrate the extension of these methods to study insecticide effects on sodium channel function in rainbow trout. 

Effects of Pyrethroids on Mouse Brain Sodium Channels... 

We explored the potency of pyrethroid action in this system using deltamethrin, NRDC 157 (3-phenoxybenzyl [lR,cis]-3-( 2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate the non-cyano analog of deltamethrin), and their nontoxic enantiomers as test compounds ( Table II). Deltamethrin produced half-maximal enhancement of veratridine-dependent activation at 25 nM, whereas NRDC 157 was approximately tenfold less potent and the nontoxic enantiomers were inactive. These findings demonstrate that the effect of pyrethroids on mouse brain sodium channels is both potent and stereospecific for toxic isomers. The relative potencies of deltamethrin and NRDC 157 in this assay also agree well with their... 

Current efforts in these studies involve a detailed characterization of pyrethroid-activator interactions and the examination of a broader range of pyrethroids and other compounds as enhancers of activation. Recently, we have found that cismethrin is one of the most effective pyrethroids in this system, producing enhancement at high concentrations equal to or greater than that observed with deltamethrin (Figure 2). The action of cismethrin in the mouse brain system is quite different from its action on neuroblastoma cell sodium channels, where it has no effect on veratridine-dependent activation but is able to antagonize the enhancement produced by other pyrethroids (5). 

Grammon DW, Sanders G. Pyrethroid-receptor interactions stereospecific binding and effects on sodium channels in mouse brain preparations. Neurotoxicology 1985 6 35-46. 

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