ubiquinone and Learning-Disabilities

Diabetes mellitus can induce impairment in learning and memory. Cognitive and memory deficits are common in older adults and especially in those with diabetes. This is mainly because of hyperglycemia, oxidative stress, and vascular abnormalities. Coenzyme Q10 (CoQ10) can decrease oxidative stress, hyperglycemia, and inflammatory markers, and improve vascular function. Therefore, the aim of the present study was to investigate the possible effects of CoQ10 on cognitive function, learning, and memory in middle-aged healthy and diabetic rats. Adult middle-aged male Wistar rats (390-460 g, 12-13 months old) were divided into 6 experimental groups. Diabetes was induced by a single i.p. injection of streptozotocin (60 mg/kg). CoQ10 (20 or 120 mg/kg, orally by gavage) was administered for 45 days. The cognitive function and learning memory of rats were evaluated using novel object recognition (NOR) and passive avoidance tests. The discrimination index of the NOR test in the diabetic groups receiving CoQ10 (20 or 120 mg/kg) and the healthy group receiving CoQ10 (120 mg/kg) was significantly higher than that in the control group. In addition, the step through latency was significantly longer and the time spent in the dark compartment was significantly shorter in the diabetic groups receiving CoQ10 than in the control group. CoQ10 supplementation can improve learning and memory deficits induced by diabetes in older subjects. In addition, CoQ10 at higher doses can improve cognitive performance in older healthy subjects.

Topics: Aging; Animals; Cognition; Diabetes Mellitus, Experimental; Dietary Supplements; Learning; Learning Disabilities; Male; Memory; Memory Disorders; Random Allocation; Rats, Wistar; Ubiquinone

The ameliorating effects of idebenone and indeloxazine hydrochloride on the impairment of memory and learning were studied in cerebral embolized rats. The embolized rats had impaired memory and learning ability in the radial maze task; these were demonstrated by a decrease in correct responses and an increase in total errors. In particular, the rats showed severe impairment of working memory, as shown by a marked increase in the numbers of re-entries into the arm that had been already visited. Idebenone (30 mg/kg, p.o.) exerted marked ameliorating effects on the impairment in the embolized rats: the drug significantly increased the correct responses and decreased the errors. Indeloxazine hydrochloride also improved the memory impairment in the embolized rats, as shown by a reduction of the errors. The ameliorating effects of these drugs may be due mainly to improvement of hypofunctions of the central nervous system. These results confirm that idebenone and indeloxazine hydrochloride may have ameliorating actions on impairment of memory and learning induced by brain hypofunction, and they suggest that the action of idebenone is more potent than that of indeloxazine hydrochloride.

Topics: Animals; Antidepressive Agents; Benzoquinones; Intracranial Embolism and Thrombosis; Learning Disabilities; Male; Memory Disorders; Morpholines; Quinones; Rats; Rats, Inbred Strains; Ubiquinone

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.

Topics: Acetylcholine; Animals; Benzoquinones; Cerebral Cortex; Cerebrovascular Disorders; Discrimination Learning; Learning Disabilities; Male; Memory Disorders; Memory, Short-Term; Quinones; Rats; Rats, Inbred Strains; Scopolamine; Serotonin; Ubiquinone

The effect of 6-(10-hydroxydecyl)-2, 3-dimethoxy-5-methyl-1, 4-benzoquinone (idebenone, CV-2619) on brightness discrimination learning of the operant type was examined in rats with central serotonergic dysfunction. The animal model was produced by feeding Wistar rats a diet deficient in tryptophan (a precursor of serotonin) as the control group. The control rats with central serotonergic dysfunction showed lower ability to learn the discrimination task (multiple VI 15 seconds extinction schedule) than normal feeding rats. Rats which were chronically administered with idebenone (60 mg/kg/day) admixed with the tryptophan deficient diet were used as an experimental group. In the control and experimental groups, total responses (R+ + R-) were significantly increased in the early stage of learning test period, compared with the normal rats. In the late stage of the learning periods, the numbers of R-decreased in idebenone-treated group but not in control group. Therefore, the correct response ratio [( R+/(R+ + R-)] X 100) was significantly higher in the treated group than in the control. The results suggest that idebenone, which has an improving action on cerebral energy metabolism and a stimulating action on central serotonergic turnover, may exert an ameliorating effect on impaired discrimination learning in rats with central serotonergic dysfunction.

Topics: Animals; Benzoquinones; Brain Diseases; Conditioning, Operant; Discrimination Learning; Learning Disabilities; Male; Quinones; Rats; Rats, Inbred Strains; Serotonin; Tryptophan; Ubiquinone; Visual Perception