© 1988 Oxford University Press
research-article |
The Effects of Type I and II Pyrethroids on Motor Activity and the Acoustic Startle Response in the Rat1
Neurotoxicology Division, Health Effects Research Laboratory, U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711
Received May 11, 1987; accepted December 14, 1987
The Effects of Type I and II Pyrethroids on Motor Activity and the Acoustic Startle Response in the Rat. CROFTON, K. M, AND REITER, L. W. (1988). Fundam Appl. Toxicol 10, 624–634. Recent data have demonstrated that the in vivo effects of low dosages of two pyrethroids, cismethrin and deltamethrin, can be differentiated. Two behavioral tests, locomotor activity and the acoustic startle response (ASR), were utilized to separate the behavioral actions of Type I and II pyrethroids using permethrin, RU11679, cypermethrin, RU26607, fenvalerate, cyfluthnn, flucythrinate, fluvalinate and p, p'-DDT. Dosage-effect functions for all compounds were determined for both figure-eight-maze activity and the ASR in the rat. All compounds were administered poin 1 ml/kg corn oil 1.5–3 hr prior to testing. All compounds produced dosage-dependent decreases in locomotor activity. The Type I compounds, permethrin and RU 11679, along with p, p'-DDT, increased amplitude and had no effect on latency to onset of the ASR. In contrast, the Type II pyrethroids, cypermethrin, cyfluthrin, and flucythrinate, decreased amplitude and increased the latency to onset of the ASR. Fenvalerate increased the amplitude, had no effect on latency, but unlike the other compounds tested, increased ASR sensitization. Fluvalinate had no effect on any measure of the ASR. These data provide further evidence of the differences between the in vivo effects of low dosages of Type I and II pyrethroids, and extend the findings of our previous work to other representatives of the two classes of pyrethroids.