The Effect of Preventive, Therapeutic and Protective Exercises on Hippocampal Memory Mediators in Stressed Rats

Background: Exercise plays a significant role in learning and memory. The present study focuses on the hippocampal corticosterone (CORT), interleukin-1 beta­(IL-1β), glucose, and brainderived neurotrophic factor (BDNF) levels in preventive, therapeutic, and protective exercises in stressful conditions. Methods: Forty male rats were randomly divided into four groups: the control group and the preventive, therapeutic, and protective exercise groups. The treadmill running was applied at a speed of 20-21m/min and a chronic stress of 6 hours/day for 21 days. Subsequently, the variables were measured in the hippocampus. Results: The findings revealed that the hippocampal CORT levels in the preventive exercise group had a significant enhancement compared to the control group. In the protective and particularly the therapeutic exercise groups, the hippocampal CORT levels declined. Furthermore, the hippocampal BDNF levels in the preventive and the therapeutic exercise groups indicated significantly decreased and increased, respectively, in comparison with the control group. In the preventive exercise group, however, the hippocampal glucose level turned out to be substantially higher than that in the control group. Conclusion: It appears that the therapeutic exercise group had the best exercise protocols for improving the hippocampal memory mediators in the stress conditions. By contrast, the preventive exercise group could not improve these mediators that had been altered by stress. It is suggested that exercise time, compared to stress, can be considered as a crucial factor in the responsiveness of memory mediators.

Effects of Cholestasis on Learning and Locomotor Activity in Bile Duct Ligated Rats

Background: Cognitive functions are impaired in patients with liver disease. Bile duct ligation causes cholestasis that impairs liver function. This study investigated the impact of cholestasis progression on the acquisition and retention times in the passive avoidance test and on the locomotor activity of rats. Methods: Cholestasis was induced in male Wistar rats by ligating the main bile duct. Locomotor activity, learning and memory were assessed by the passive avoidance learning test at day 7, day 14, and day 21 post-bile duct ligation. The serum levels of bilirubin, alanine aminotransferase, and alkaline phosphatase were measured. Results: The results showed that acquisition time and locomotor activity were not affected at day 7 and day 14, but they were significantly (P < 0.05) impaired at day 21 post-bile duct ligation compared with the results for the control group. Additionally, memory was significantly impaired on day 7 (P < 0.01), day 14, and day 21 (P < 0.001) compared with the control groups. The levels of total bilirubin, direct bilirubin, indirect bilirubin, alanine aminotransferase, and alkaline phosphatase were significantly higher at day 7, day 14, and day 21 post-bile duct ligation compared with the levels in the sham group. Conclusion: Based on these findings, both liver and memory function were affected in the early stage of cholestasis (7 days after bile duct ligation), while learning and locomotor activity were impaired at 21 days after bile duct ligation following the progression of cholestasis.

effect of synchronized running activity with chronic stress on passive avoidance learning and body weight in rats

Different stressors induce learning and memory impairment and physical activity influence learning and memory enhancement. In this research, we investigated the effect of synchronized running activity with stress on acquisition and retention time of passive avoidance test. Male Wistar rats were randomly divided into five groups as follows: Control [Co], Sham [Sh], Exercise [Ex], Stress [St], synchronized exercise with stress [St and Ex] groups. Chronic restraint stress was applied by 6 h/day for 21 days and treadmill running 1 h/day for 21 days. For evaluation of learning and memory, initial and step-through latency were determined at the end of study by using passive avoidance learning test. Our results showed that: [1] Exercise under no stress provides beneficial effects on memory acquisition and retention time compared to Control group; especially retention time had significantly [P < 0.05] increased in exercised group. [2] Chronic stress with and without synchronized exercise significantly [P < 0.01, P < 0.05, respectively] impaired acquisition and retention time. [3] Body weight differences were significantly [P < 0.01, P < 0.001 and P < 0.001] lower than Control group in exercise, stress and synchronized exercise with stress groups, respectively. [4] Adverse effects of restraint stress [psychical stress] were probably greater than physical activity effects on learning, memory and weight loss. The data confirmed that synchronized exercise with stress had not significantly protective role in improvement of passive avoidance acquisition and retention time; hence it did not significantly improve learning and memory deficit in stressed rats; whereas exercise alone could improve memory deficit in rats

effect of synchronized forced running with chronic stress on short, mid and long- term memory in rats

Impairment of learning and memory processes has been demonstrated by many studies using different stressors. Other reports suggested that exercise has a powerful behavioral intervention to improve cognitive function and brain health. In this research, we investigated protective effects of treadmill running on chronic stress-induced memory deficit in rats. Fifty male Wistar rats were randomly divided into five groups [n=10] as follows: Control [Co], Sham [Sh], Stress [St], Exercise [Ex] and Stress and Exercise [St and Ex] groups. Chronic restraint stress was applied by 6h/day/21days and also treadmill running at a speed 20-21m/min for 1h/day/21days. Memory function was evaluated by the passive avoidance test in different intervals [1, 7 and 21 days] after foot shock. Our results showed that: 1] Although exercise alone showed beneficial effects especially on short and mid-term memory [P<0.05] in comparison with control group, but synchronized exercise with stress had not significantly improved short, mid and long-term memory deficit in stressed rats. 2] Short and mid-term memory deficit was significantly [P<0.05] observed in synchronized exercise with stress and stress groups with respect to normal rats. 3] Memory deficit in synchronized exercise with stress group was nearly similar to stressed rats. 4] Helpful effects of exercise were less than harmful effects of stress when they were associated together. The data correspond to the possibility that although treadmill running alone has helpful effects on learning and memory consolidation, but when it is synchronized with stress there is no significant benefit and protective effects in improvement of memory deficit induced by chronic stress. However, it is has a better effect than no training on memory deficit in stressed rats

effect of treadmill running on passive avoidance learning in animal model of Alzheimer disease

Alzheimer's disease was known as a progressive neurodegenerative disorder in the elderly and is characterized by dementia and severe neuronal loss in the some regions of brain such as nucleus basalis magnocellularis. It plays an important role in the brain functions such as learning and memory. Loss of cholinergic neurons of nucleus basalis magnocellularis by ibotenic acid can commonly be regarded as a suitable model of Alzheimer's disease. Previous studies reported that exercise training may slow down the onset and progression of memory deficit in neurodegenerative disorders. This research investigates the effects of treadmill running on acquisition and retention time of passive avoidance deficits induced by ibotenic acid nucleus basalis magnocellularis lesion. Male Wistar rats were randomly selected and divided into five groups as follows: Control, sham, Alzheimer, exercise before Alzheimer, and exercise groups. Treadmill running had a 21 day period and Alzheimer was induced by 5 micro g/ micro l bilateral injection of ibotenic acid in nucleus basalis magnocellularis. Our results showed that ibotenic acid lesions significantly impaired passive avoidance acquisition [P < 0.01] and retention [P < 0.001] performance, while treadmill running exercise significantly [P < 0.001] improved passive avoidance learning in NBM-lesion rats. Treadmill running has a potential role in the prevention of learning and memory impairments in NBM-lesion rats