Effects of aniracetam on one-trial passive avoidance tests and cholinergic neurons in discrete brain regions of rats.
Using rats in one-trial passive avoidance tests, the anti-amnesic effects of the nootropic drug aniracetam were investigated; moreover, the action of aniracetam upon the cholinergic system in the brain was studied. In one-trial passive avoidance tests, aniracetam prolonged significantly the retention time for 100 mg/kg, p.o. However, the retention-prolonging effect was diminished when the dose was increased to 300 mg/kg p.o. Investigation of the action of the drug upon the cholinergic system revealed that ACh and choline content in the corpus striatum was not increased by any doses of aniracetam. ACh content in the hippocampus was increased by doses of 100-300 mg/kg, p.o., but choline was not significantly increased by any doses, while in the cerebral cortex ACh content was significantly increased by a dose of 300 mg/kg, p.o. In addition, the decrease in hippocampal ACh and choline content following an injection of scopolamine was lessened by aniracetam 100 mg/kg, p.o. and 100-300 mg/kg, respectively. In order to elucidate the mechanism of these actions of aniracetam, the ACh-releasing action and changes in choline content of the extracellular spaces in the hippocampus were investigated, but no effects were observed. The results obtained indicate that aniracetam has an inhibitory effect upon scopolamine-induced amnesia. The mechanism of this effect may be an action upon the cholinergic system; therefore, some action with respect to the impairment of cholinergic neurotransmission in the hippocampus induced by scopolamine appears to be of particular importance.
Department of Pharmacology, Taiho Pharmaceutical Co., Ltd., Tokushima, Japan.
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Toide
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001921:Brain / Q000166:cytology / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D002794:Choline / Q000378:metabolism; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D003956:Dialysis; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects*; D010275:Parasympathetic Nervous System / Q000187:drug effects*; D011760:Pyrrolidinones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012601:Scopolamine / Q000494:pharmacology
D011760:Pyrrolidinones; C036466:aniracetam; D012601:Scopolamine; D002794:Choline; D000109:Acetylcholine