Action of diisopropylfluorophosphate and of diacetylmonoxime on acetylcholine levels and on cholinesterase activity in the central nervous system.

The modification of the acetylcholinesterase (AChE) activity and of the acetylcholine (ACh) levels caused by diisopropylfluorophosphate (DFP) alone and in association with 300 mg/kg of diacetylmonoxime (DAM) have been studied in the olfactory brain, in the cortex and in the medulla-pons of the rat. DFP caused a reduction of the levels of ACh at 0.25 and 0.5 mg/kg. An increase of the levels of ACh was observed at 4.0 mg/kg of DFP only in the olfactory brain and in the cortex. A dose-dependent reduction of the AChE activity was observed after DFP. DAM reactivated the AChE activity to the levels of the controls after 0.25 and 0.5 mg/kg of DFP. In this experimental situation, the ACh levels returned to the control levels after 0.25 mg/kg of DFP and, in the medulla-pons, also after 0.5 mg/kg of DFP. DAM caused a partial recovery of the AChE activity but no modification of the ACh levels at 1.0, 2.0 and 4.0 mg/kg of DFP.