Effect of pyrethroids on pentobarbital-induced sleeping time in relation to the chemical structure

The effect of pyrethroids on pentobarbital-induced sleeping time was examined in mice. Pentobarbital-induced sleeping time was defined as the time interval from loss of righting reflex to reappearance of righting reflex. Mice were administered pyrethroids orally 2 h before the intraperitoneal injection of pentobarbital at a dose of 45 mg/kg. Pyrethroids with a cyano group on the alcohol moiety, such as cyphenothrin, cypermethrin, fenvalerate and fenpropathrin shortened the pentobarbital-induced sleeping time, while pyrethroids with an ethynyl group on the acid moiety, such as prallethrin, furamethrin and empenthrin, prolonged sleeping time. Pyrethroids with neither a cyano nor an ethynyl group had no effect on sleeping time. We, thus, found a clear relationship between the chemical structure of pyrethroids and their effect on pentobarbital-induced sleeping time.