Idebenone improves learning and memory impairment induced by cholinergic or serotonergic dysfunction in rats.
The effects of idebenone, a cerebral metabolic enhancer, on learning and memory impairment in two rat models with central cholinergic or serotonergic dysfunction were investigated using positively reinforced learning tasks. A delayed alternation task using a T maze was employed to test the effect of idebenone on short-term memory impairment induced by a cholinergic antagonist, scopolamine. A correct response, defined as a turn toward the arm opposite to that in the forced run, was rewarded with food pellets. Scopolamine (0.2 and 0.5 mg/kg, i.p.) significantly decreased the correct responses to the chance level in the 60-s-delayed alternation task. The scopolamine (0.2 mg/kg, i.p.)-induced impairment of short-term memory was improved by idebenone (3-30 mg/kg, i.p.) or an acetylcholinesterase inhibitor, physostigmine (0.1 and 0.2 mg/kg, i.p.), administered simultaneously. The central serotonergic dysfunction model was produced by giving rats a diet deficient in tryptophan, a precursor of serotonin. The rats fed on a tryptophan-deficient diet (TDD) showed a slower learning process in the operant brightness discrimination task (mult V115 EXT) than did rats fed on a normal diet. Idebenone (60 mg/kg/day) admixed with the TDD decreased the number of lever-pressing responses emitted during the extinction periods. The percentage of correct responses was significantly higher in the idebenone-treated group than in the control TDD group. These results suggest that idebenone may improve both the impairment of short-term memory induced by a decreased cholinergic activity and the retardation of discrimination learning induced by central serotonergic dysfunction.
Yamazaki
N
N
Central Research Division, Takeda Chemical Industries, Ltd., Osaka, Japan.
Nomura
M
M
Nagaoka
A
A
Nagawa
Y
Y
D000109:Acetylcholine / Q000502:physiology*; D000818:Animals; D016227:Benzoquinones; D002540:Cerebral Cortex / Q000187:drug effects; D002561:Cerebrovascular Disorders / Q000150:complications* / Q000503:physiopathology*; D004193:Discrimination Learning / Q000187:drug effects; D007859:Learning Disabilities / Q000188:drug therapy*; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced / Q000188:drug therapy*; D008570:Memory, Short-Term / Q000187:drug effects; D011809:Quinones / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012601:Scopolamine; D012701:Serotonin / Q000502:physiology*; D014451:Ubiquinone / Q000031:analogs & derivatives
D016227:Benzoquinones; D011809:Quinones; D014451:Ubiquinone; D012701:Serotonin; D012601:Scopolamine; C036619:idebenone; D000109:Acetylcholine