Pyrethroid effects on operant responding and feeding.

The effects of permethrin, its cis and trans isomers, and deltamethrin on operant behavior and food intake were examined. Male Sprague-Dawley rats were trained to respond on a VI20 second schedule of food reinforcement. Rats were injected intraperitoneally with pyrethroids or their Emulphor vehicle 20 minutes prior to testing. Technical grade permethrin (15-60 mg/kg) produced a dose-related decrease in operant response rate. The 60 mg/kg dose decreased rates by 60%. Lower doses of cis-permethrin (30 mg/kg) and deltamethrin (2 mg/kg) also produced significant decreases in response rate. A 30 mg/kg dose of trans-permethrin was without effect. Food intake was also measured for 1.5 and 24 hour periods after tech-permethrin treatment. Food intake was decreased over both intervals by the 60 mg/kg dose. The results of these studies indicate that subconvulsive doses of pyrethroid insecticides can have significant effects on learned behavior and food intake.