Correlation between organophosphate poisoning, acetylcholinesterase inhibition, and increased cyclic GMP levels in malathion-treated insects.
Organophosphate poisoning with malathion caused large increases (up to 125 and 440%, respectively) in the level of cyclic GMP in larvae of Mamestra configurata Wlk. and in the fly Sarcophaga bullata Parker. Cyclic AMP was little affected. The malathion-induced increase in cyclic GMP was time and dose dependent. Time-course studies with the head and thorax of S. bullata demonstrated that the increase in cyclic GMP level occurred precipitously after a lag period  of about 1 h, during which time the activity of acetylcholinesterase (EC 3.1.1.7) was progressively inhibited. The abrupt increase in cyclic GMP began when acetylcholinesterase activity had been inhibited to a sufficient extent to permit accumulation of acetylcholine. It is suggested that the accumulation of acetylcholine in the malathion-poisoned insects caused cyclic GMP levels to rise.  Cyclic GMP may have a role in cholinergic transmission in normally functioning insect neural tissue. Increased levels of cyclic GMP induced by organophosphate and organocholorine (Bodnaryk, R. P. (1976) Can. J. Biochem. 54, 957-962) insecticides appear to be a vital and previously unrecognized biochemical lesion in insects poisoned by these compounds.
D000818:Animals; D002800:Cholinesterase Inhibitors; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism*; D004175:Diptera / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007814:Larva; D007915:Lepidoptera / Q000378:metabolism; D008294:Malathion / Q000494:pharmacology*
D002800:Cholinesterase Inhibitors; D000242:Cyclic AMP; D006152:Cyclic GMP; D008294:Malathion