ABSTRACT
ObjectiveTo investigate the effects of exercise on the hippocampal formation and the myelinated nerve fibers in the hippocampal formation of middle-aged rats. MethodsTen 14-month female SD rats were randomly divided into exercise group and sedentary group.Rats in the exercise group were forced to run on a treadmill for 4 months. After 4 months, spatial learning capacity of two group rats was tested using the Morris water maze.Then, the hippocampal formation and the myelinated nerve fibers in the hippocampal formation were quantitatively estimated using transmission electronic microscopy and stereological techniques. Results Treadmill running enhanced the spatial learning capacity of the rats. The volume of hippocampal formation and the total length of the myelinated nerve fibers in the hippocampal formation were significantly increased after 4 months exercise.However,there was no significant difference in the total volume of the myelinated fibers in the hippocampal formation between the two groups.The absolute distributions of the total length of the myelinated fibers in the hippocampal formation of two groups indicated that the exercise-induced increase of the total length of the myelinated nerve fibers in the hippocampal formation was mainly due to the increase of the myelinated fibers with small diameter. Conclusions Four months running exercise remarkably influence the spatial learning capacity,hippocampal formation and the myelinated fibers in the hippocampal formation of the middle-aged famale SD rats. The present results reveal a potential mechanism for the fact that exercise might improve brain function.
ABSTRACT
ObjectiveTo investigate the effects of short-term enriched environment on the hippocampal formation and the myelinated fibers in the hippocampal formation of mid-aged male rats. MethodsTwenty 14-month old male SD rats were randomly divided into enriched group and standard group. Enriched rats were reared in enriched environment and standard rats were reared in standard environment for 4 months. Then, the spatial learning capacity of enriched rats and standard rats was tested with the Morris water maze. After the Morris water maze test, the total volume of the hippocampal formation and the myelinated nerve fibers in the hippocampal formation were quantitatively estimated with transmission electronic microscopy technique and stereological methods. Results There was not significant difference in the spatial learning capacity between enriched group and standard group. The total volume of the hippocampal formation of enriched rats was not significantly increased by 4.6% when compared with that of standard rats. The total volume, total length and mean diameter of the myelinated nerve fibers in the hippocampal formation of enriched rats were significantly increased when compared with those of standard rats. Conclusions Four-months enriched environment significantly affected the myelinated fibers in the hippocampal formation of mid-aged male SD rats. The present results might provide an important theoretical basis for searching the ethology strategy to delay the progress of brain aging in the future.
ABSTRACT
Objective:To investigate the effects of the short-term enriched environment on the spatial learning capacity of middle-aged rats and to figure out if the effects are sex dependent.Methods:14-month old male and female Sprague-Dawley rats were randomly divided into enriched group and standard group.Enriched rats were reared in enriched environment and standard rats were reared in standard environment for 4 months prior to the assessment in Morris water maze.Results:Compared with the standard environment, enriched environment could only promote the spatial learning capacity of the middle-aged female rats.The spatial learning capacity of standard male rats was superior to that of the standard females;however,the spatial learning capacity of enriched male rats was equal to that of the enriched females.Conclusion:Short-term enriched environment remarkably improved the spatial learning capacity of middle-aged female rats.The spatial learning capacity of middle-aged male rats was better than female rats,but the plasticity of the brain function in middle-aged female rats may be better than that in male rats.The results in the present study provide an important theoretical basis for the future study that searches for behavioral strategy to postpone the progress of brain aging.