Effects of cypermethrin on the electroencephalographic activity of the rat:: A model of chemically induced seizures

Cypermethrin is a potent representative member of the type II pyrethroid insecticides. This pyrethroid is used worldwide and has become a part of our environment. Until the present study, little information about its toxic effects in the central nervous system (CNS) was available. The aim of this study was, then, to determine the effects of repeated exposure to cypermethrin by means of assessing the electroencephalographic (EEG) activity in the rat. Cypermethrin was administered daily in a 300 mg/kg IP dose, below the LD(50) value. After daily administration, the EEG activity was recorded and evaluated for 30 min. Paroxysmal epileptic activity appeared after the first and second days of cypermethrin administration. Frequency and numbers of bursts of epileptic activity also increased throughout the days of exposure to cypermethrin. Some of the paroxysmal events were present with behavioral anomalies, such as generalized tonic-clonic seizures. These effects are important because they could be related to the incidence of epileptic activity in humans chronically exposed to cypermethrin. (C) 1999 Elsevier Science Inc. All rights reserved.