Effects
of two classes of pyrethroids, permethrin and resmethrin (type I), cypermethrin and deltamethrin (type 11), on basal (calmodulin-deficient) and calmodulin stimulated activities of Ca2+ ATPase and adenylate cyclase from rat brain were studied in vifro. None of the pyrethroids inhibited synaptosomal basal CaZ+ ATPase, but permethrin and deltamethrin inhibited basal adenylate cyclase in the nuclear fraction of a brain homogenate. Both groups of pyrethroids decreased the calmodulin activated Ca" ATPase and adenylate cyclase from brain synaptosomes and nuclear fraction. The results indicate that calmodulin-stimulated CaZ+ ATPase is more sensitive to type I1 pyrethroids and pyrethroids are more effective on calmodulin stimulated enzymes than basal enzyme activities. Since calmodulin, adenylate cyclase and CaZ+ ATPase are known to participate in various brain processes, it is possible that pyrethroids alter neural transmission, however, additional in vivo work would be needed to confirm this possibility.
MATERIALS AND METHODS
Animals
Male Sprague-Dawley rats weighing about 250 g each were obtained from Charles River Breeding Laboratories, Wilmington, MA. for these experiments.