The effects of triethylcholine and hemicholinium-3 on the acetylcholine content of rat brain

Intraventricular injections of triethylcholine made in conscious rats produced catatonia preceded in a number of animals by a seizure. Hemicholinium-3 also produced a brief period of catatonia but any seizures which occurred did so only after an interval of about 1 hr. Both compounds reduced the total amount of brain acetylcholine and this effect was prevented when choline was administered at the same time. A small intraventricular dose of triethylcholine, which was not sufficient to affect the total amount of brain acetylcholine, did reduce the amount of free acetylcholine. A larger dose decreased both the free and bound components. An intraperitoneal injection of triethylcholine had no effect on brain acetylcholine. The catatonia and seizures produced by triethylcholine and hemicholinium-3 cannot be related to any apparent changes in either brain acetylcholine content or acetylcholinesterase activity.