Effect of diisopropyl phosphofluoridate on analgesia and motor behavior in the rat

Abstract

1. 1. Diisopropyl phosphofluoridate (DFP) produced analgesia and behavioral depression. Morphine, 3.0 mg/kg, and DFP, 1.5 mg/kg, produced quantitatively similar degrees of analgesia. 2. 2, Antinociception induced by DFP was reversed by atropine and also by naloxone, a pure narcotic antagonist. Morphine-induced analgesia was reversed only by naloxone. 3. 3. Serotonin (5-HT) levels were increased by DFP administration in several brain regions. Pretreatment of the animals with para-chlorophenylalanine (PCPA) prevented the DFP augmentation of 5-HT levels but did not affect behavioral effects or analgesia produced by DFP. 4. 4. These results suggest that DFP acts via the central cholinergic system to produce analgesia, that this effect may not depend on 5-HT, and that DFP and morphine-induced analgetic states may be related.