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  Background & objectives : Epileptic seizures accompany disturbances in learning, memory, and cognitive skills. With regard to antiepileptic potential of curcumin and its beneficial effect on memory, the effect of its administration on learning and memory in kainate-epileptic rats was investigated.

  Methods: Forty male rats were divided into sham, positive control ( valproate-treated epileptic), epileptic, and two curcumin-treated epileptic groups. Rat model of epilepsy was induced by unilateral intrahippocampal administration of 4 μg of kainate per rat. Rats received intraperitoneal injection of curcumin (50 and 100 mg/kg) daily for 1 week before surgery. For evaluation of learning and memory, initial (IL) and step-through latencies (STL) were determined using passive avoidance test and alternation behavior percentage was obtained according to Y maze test.

  Results: Regarding IL, there was no significant difference between the groups. In contrast, STL significantly decreased in curcumin-50-treated epileptic group (p<0.05) (a change from 263.1 to 184.5 s). However, this parameter significantly increased in curcumin-100-treated epileptic group as compared to epileptic group (p<0.01) (a change from 263.1 to 220.3 s). In addition, STL was also significantly higher in valproic acid-treated epileptic group versus epileptic group (p<0.05) (a change from 145.7 to 210.3 s). Alternation percentage was also significantly higher in curcumin-50- and curcumin-100-treated epileptic groups relative to epileptic group (p<0.05) (a change from 60.5 to 77.6 and 80.3%).

  Conclusion: Curcumin could dose-dependently enhance the consolidation and recall in epileptic animals and could improve spatial memory in such animals.

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Background & objectives: Ritalin is one of the drugs used in the treatment of attention-deficit/hyperactivity disorder (ADHD). This study aimed to investigate the comparative effect of Ritalin with grape seed extract on passive avoidance learning in adult male rats.

Methods: In this experimental study, 40 adult male Wistar rats divided randomly into 5 groups of 8 rats including control, sham and three experimental groups. The control group received no treatment. The sham group received 1 ml of distilled water per day. At the same time the experimental groups received 100 mg/kg grape seed extract, 1 mg/kg Ritalin or 100 mg/kg grape seed extract together with 1 mg/kg of Ritalin by gavage for 28 days. For measuring the amount of avoidance learning, Shuttle box was used. Data analyzed by ANOVA and consistent Tukey's tests using SPSS-18 software and p>0.05 considered as significant.

Results: The results showed that Ritalin decreases the passive avoidance learning, while the grape seed extract alone or together with Ritalin increases passive avoidance learning.

Conclusion:  The outcome of this research shows that taking Ritalin leads to decreasing passive avoidance learning. However, the simultaneous taking Ritalin with grape seed extract inhibits the Ritalin effect and increasing the learning.

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Background & objectives: Diabetes mellitus cause cognitive defects. Royal Jelly has been claimed to improve the neurological damage caused by diabetes. In this study, the effect of oral administration of royal jelly on memory and passive avoidance learning was studied in diabetic male rats.
Methods: This experimental study was conducted in Qazvin University of Medical Sciences on 48 male Wistar rats. The animals were divided into control, diabetic without treatment, diabetic recipient of glibenclamide (600 μg/kg) and three diabetic groups treated with 50, 100 and 200 mg/kg royal jelly (n=8). Diabetes was induced in the animals by intraperitoneal injection of streptozotocin (60mg/kg/ip). Treatment in the groups performed by gavage from the onset of hyperglycemia for 30 days. At the end of the test, the passive avoidance learning and memory and blood glucose were measured. Data were analyzed by by SPSS software using ANOVA and post-hoc LSD tests, and p<0.05 was considered significant.
Results: Diabetes reduced the latency time of dark room entering. Royal jelly treatment delayed the entrance to the dark room significantly at 24 h, 48 h and 2 weeks after the shock, especially at doses of 100 (p<0.05) and 200 mg/kg (p<0.01) compared to untreated diabetic animals.
Conclusion: According to the results, diabetes causes memory impairment, and royal jelly administration can reduce the memory impairment due to diabetes.

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Background & objectives: Epidemiological Studies have shown that diabetes increase the risk of developing Alzheimer’s disease (AD).also several studies have confirmed that long term use of Metformin (Met) improves cognitive function in diabetic patients.  The aim of the present study was to investigate the effects of Met on learning and memory in diabetic and non-diabetic rats.
Methods: Animals were divided into 2 groups including healthy and diabetic group. In healthy group, normal rats subdivided into control, saline and Met groups which received saline or Met (500mg/kg) and in diabetic group including DM, DM+saline and DM+Met subgroups, diabetic rats  received saline or Met (100, and 200mg/kg) for 20 days. Diabetes was induced by intraperitoneal injection (ip) of streptozotocin (STZ).
Results: Our results showed that Met (500mg/kg, ip) impaired spatial learning but improved spatial memory in normal rats. The results also showed that Met improved learning and memory in diabetic rats in a dose dependent manner, so that the rats of DM+Met group compared to DM+saline group found platform in less time and with less distance traveled. Met also increased the percentage of time elapsed and the distance swum in the target quadrant in diabetic rats during the probe trial.
Conclusion: An intraperitoneal injection of STZ resulted in a significant decline in learning and memory and treatment with Met can enhance learning and memory in a dose dependent manner, therefore, it is useful for treatment of cognitive impairment in diabetic patients.
 

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Background & objectives: Mitochondrial dysfunction is one of the main risk factors for neurological diseases which are associated with aging. On the other hand, aerobic exercise has beneficial effects on the brain health and cognitive function, and also improves mitochondrial dynamics. Therefore, the aim of the present study was to investigate the effect of 4 weeks of aerobic exercise on spatial learning, memory performance and mitochondrial dynamics in the hippocampal tissue of old rats.
Methods: For this purpose, 14 male Wistar rats at 20 months of age were randomly divided into 2 groups: aerobic exercise (n=7) and control group (n=7). The exercise group performed 4 weeks of treadmill training (5 days per week at a speed of 10 to 15 m/min). Forty-eight hours after the last training session, the animals underwent behavioral tests. Twenty-four hours after the behavioral test, all rats were killed and hippocampal tissue was extracted. The mRNA expression of OPA1, Mfn2 and Drp1 genes were assayed using Real Time-PCR. The Independent t test was used for statistical analysis.
Conclusion: Aerobic exercise in old animals improved spatial learning and memory performance, increased hippocampal OPA1 gene expression, and decreased Drp1 gene expression compared to the control group (p≤0.01).
Conclusion: It seems that aerobic exercise can improve the function of brain mitochondria by modulating fusion and fission processes and it can be considered as an effective non-pharmacological method to deal with aging-related learning and memory perturbations.

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Background & objective: Alzheimer's disease (AD) is the most common cause of dementia among the elderly, threatening their quality of life. On the other hand, regular exercise is associated with improved brain health and cognitive function. However, the mechanisms of these benefits have not yet been fully elucidated. Therefore, the aim of this study was to investigate the effect of 4 weeks of moderate intensity interval aerobic training on cognitive function and expression level of PGC1α and VEGF genes in the hippocampus of old rats with AD.
Methods: For this purpose, 20-month-old male Wistar rats were divided into three groups of AD (n=8), AD+exercise training (n=8) and control (n=8). Intra-hippocampal injection of Aβ₄₂ was used to induce AD. The animals in the exercise group performed moderate-intensity interval aerobic exercise for 4 weeks, 5 days a week. To assess spatial learning and memory, the animals underwent the Morris water maze test 48 hours following the last training session. Then, the animals were killed and hippocampal tissue was extracted. Real time-PCR method was used to measure gene expression. Statistical analysis was performed using one-way analysis of variance and Pearson correlation coefficient at the significance level of p£0.05.
Results: The results showed that Aβ₄₂ injection impaired spatial learning and memory function and reduced the expression level of PGC1α and VEGF genes in hippocampal tissue (p£0.05). Aerobic exercise improved spatial learning and memory function and increased PGC1α and VEGF genes expression (p£0.01). Also, a significant positive relationship was observed between the PGC1α and VEGF gene expression levels in the hippocampus (r= 0.859, p≤0.01). In addition, there was a significant inverse relationship between PGC1α and VEGF genes expression and the mean time spent to find the platform (r= -0.9, p£0.01 and r= -0.750, p£0.01, respectively), and a significant positive relationship with the time spent in the target quadrant (r= -0.794, p£0.01 and r= -0.632, p£0.01, respectively).
Conclusion: In general, aerobic training improves spatial learning and memory performance in old animals with AD; up-regulation of the exercise-induced PGC1α/VEGF pathway in the brain, at least in part, appears to be involved in this adaptation.