Effect of organophosphorus compounds on acetylcholine synthesis in brain

Effects of parathion and di-isopropyl fluorophosphate (DFP) on acetylcholine (ACh) synthesis in the mouse brain were investigated. In addition to well known cholinesterase (ChE) inhibition, parathion showed inhibitory effects on the activity of synaptosomal choline acetyltransferase (ChAc), and on the uptake of [14C-methyl]-choline and ACHh synthesis in subcellular fractions of the brain. DFP inhibited ChE activity, but had no significant effects on the choline uptake and ACh synthesis per se. Possible significance of these findings in the pharmacological actions of organophosphorus compounds is briefly discussed.