The Effects of Crowding Stress on Cortex of MouseCerebellum

Abstract

Background and Objectives: Nowadays, the remarkable growth of population and its subsequent overcrowding in big cities maybe an important factor in causing neural system sensivity against environmental agents.Taking this issue into account, the present study aimed at investigating the effects of social stress on cortex of mouse cerebellum.Methods: 60 adult male mice of the NMRI strain were selected at the age of 5-6 weeks and were randomly divided into 6 groups. In the first three groups, 5 animals per cage (as control), 10 animals per cage (mild stress condition) and 15 animals per cage (sever stress condition) were housed for one month and the next three groups with same condition in same manner were housed for two months (groups 4, 5 and 6). All animals were anesthetized and weighed. The samples of right lobe of cerebellum were removed and fixed for light microscopic study. The thickness of the molecular and granular layers and the number and height of purkinje cells were analyzed by Image Tool soft ware.Results: The results showed that the mean weight of animals in group 3 and group 6(sever stress condition) were significantly reduced compared to the control group (p<0.001), while the mean weight of animals in mild stress conditions was not significantly reduced compared to controls. The mean number of purkinje cells between groups 2 and 6 showed a significant difference (p<0.004). The mean height of purkinje cells in all stress groups (group 2, 3, 5 and 6) was significantly reduced compared to group 1 (p<0.001). The thickness of the molecular and granular layers in all stress groups showed insignificant difference compared to the control group.Conclusion: It can be concluded that the social stress has a detrimental effect on cortex of mouse cerebellum by decreasing the weights of animals, the number and height of cerebellar purkinje cells.

Keywords

• Crowding Stress
• Purkinje Cells
• Mice
• Cerebellum