Influence Of Altitude Environment On The Adult Neurogenesis In Mice

In recent years, people have found that neural stem cells still exist in human and animals, and these neural stem cells can constantly generate new neurons and astrozytes in life span. In most adult mammalian CNS, active neurogenesis occurs throughout life in the subventricular zone (SVZ) of the lateral ventricle and in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. However, the mechanisms of proliferation, differentiation and survival about adult neurogenesis remain unclear. It has been found that experimental changes of living environment can significantly affect the proliferation, differentiation and survival of neural stem cells in the SGZ of the dentate gyrus. However,it has not been reported that how the changes of natural environment affect the adult neurogenesis.Objective:The aim of this study is to investigate the influence of high-altitude living environment of the Qinghai-Tibet Plateau on the proliferation and differentiation of adult neural stem cells in the SGZ of the dentate gyrus in mice.Methods:Healthy adult Kunming mice were divided into two groups:one altitude of control group is1519m in Lanzhou, the other altitude of experimental group is4547m in Tuotuohe on Qinghai-Tibet Plateau.We monitored the weight of the mice. Immunocytochemistry was used to investigate quantificationally the proliferation, differentiation and more than once proliferation of adult neural stem cells in the SGZ of the dentate gyrus in mice. Meanwhile, we investigate correlation analysis between proliferation of adult neural stem cells and the weight of the mice.Results:The weight of mice decrease after living in altitude environment. The BrdU-positive cells of experimental group significantly reduced by40%compared with the control group (P<0.05), indicating that the altitude environment inhibit the proliferation of adult neural stem cells in dentate gyrus of mice. The proliferation of adult neural stem cells and the weight of the mice was no-associative. The percentage of BrdU/Prox-1double labeled positive cells in BrdU-positive cells showed no significant differences between the experimental group and the control group (P>0.05), indicating that the differentiation of newly generated cells were not influenced by the altitude environment. More than90%BrdU-positive cells in dentate gyrus were prox-1-postive, indicating that most of the newly generated cells differentiated into granule cells (neurons).Conclusion:Under the high-altitude and hypoxia of the Qinghai-Tibet Plateau, the weight of mice decrease, and the proliferation of neural stem cells in the SGZ of the dentate gyrus of mice is significantly decreased.However it’s no-associative between the proliferation of adult neural stem cells and the weight of the mice, and their rate of differentiation to the granule cells is not significantly affected. Therefore these changes may helps the animals adapt to the high altitude surroundings.