The effects of short-term enriched environment on capillaries of the middle-aged rat cortex.

There has been no study investigating the effects of enriched environment on the capillaries of cortex with new stereological methods. In the present study, both 14 month female and male Sprague-Dawley rats were randomly divided into enriched environment (EE) rats and standard environment (SE) rats. EE rats were reared in enriched environment and SE rats were reared in standard environment for 4 months. The effects of short-term enriched environment on the cortex volume and on the total volume, total length, total surface area and mean diameter of the capillaries in the cortex of mid-aged Sprague-Dawley rats were quantitatively investigated with immunohistochemistry technique and unbiased stereological methods. There were no significant differences in the cortex volume, the total length and total surface area of the capillaries in the cortex between EE rats and SE rats. The total volume of the capillaries in the cortex of female EE rats and male EE rats was significantly increased when compared to female SE rats and male SE rats. The mean diameter of the capillaries in the cortex of female EE rats was significantly decreased when compared to that in female SE rats, but there was no significant difference in the mean diameter of the capillaries in the cortex between male EE rats and male SE rats. The present results indicate that enriched environment had a positive effect on the capillaries in the cortex of middle-aged rats. The present study might provide an important morphological basis for searching the ethology strategy to delay the progress of brain aging in the future.