Therapeutic action of acetylcholine in malathion toxicity.

Administration of malathion to the developing Philosamia ricini larvae induces accumulation of acetylcholine, marked inhibition of acetylcholinesterase activity, depletion of all nutrients, heavy weight loss and high mortality. Pre-treatment of the larvae with acetylcholine via feed, reduces malathion toxicity and conversely, feeding of acetylcholine to malathion-treated larvae reverses the toxic effects. Resumption of normal control feed to malathion-treated insects results in higher mortality than in insects fed acetylcholine after exposure to malathion. This emphasizes the therapeutic action of acetylcholine. Feeding of a mixture of equal quantities of malathion and acetylcholine recorded significantly lower mortality among insects in comparison to those fed malathion alone. This further supports the protective action of acetylcholine. Reversal of malathion toxicity and the protective action of acetylcholine have been attributed to the mediation of choline, an essential insect vitamin that gets released as a catabolic product of acetylcholine.