title: Reduced Cerebral Oxygen Content in the DG and SVZ In Situ Promotes Neurogenesis in the Adult Rat Brain In Vivo.
abstract: Neurogenesis in the adult brain occurs mainly within two neurogenic structures, the dentate gyrus (DG) of the hippocampus and the sub-ventricular zone (SVZ) of the forebrain. It has been reported that mild hypoxia promoted the proliferation of Neural Stem Cells (NSCs)in vitro. Our previous study further demonstrated that an external hypoxic environment stimulated neurogenesis in the adult rat brain in vivo. However, it remains unknown how external hypoxic environments affect the oxygen content in the brain and result in neurogenesis. Here we use an optical fiber luminescent oxygen sensor to detect the oxygen content in the adult rat brain in situ under normoxia and hypoxia. We found that the distribution of oxygen in cerebral regions is spatiotemporally heterogeneous. The Po2 values in the ventricles (45∼50 Torr) and DG (approximately 10 Torr) were much higher than those of other parts of the brain, such as the cortex and thalamus (approximately 2 Torr). Interestingly, our in vivo studies showed that an external hypoxic environment could change the intrinsic oxygen content in brain tissues, notably reducing oxygen levels in both the DG and SVZ, the major sites of adult neurogenesis. Furthermore, the hypoxic environment also increased the expression of HIF-1α and VEGF, two factors that have been reported to regulate neurogenesis, within the DG and SVZ. Thus, we have demonstrated that reducing the oxygen content of the external environment decreased Po2 levels in the DG and SVZ. This reduced oxygen level in the DG and SVZ might be the main mechanism triggering neurogenesis in the adult brain. More importantly, we speculate that varying oxygen levels may be the physiological basis of the regionally restricted neurogenesis in the adult brain.
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China; Brain Research Center, College of Basic Medical Sciences, Third Military Medical University, Chongqing, China.
authors.forename: Kuan
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Yanzhao
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhao
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Liying
authors.initials: L
authors.lastname: Wu
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Kuiwu
authors.initials: K
authors.lastname: Wu
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Lun
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Dahu
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China.
authors.forename: Yongqi
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China; Beijing Institute for Brain Disorders, 10 Xitoutiao, You Anmen, Fengtai District, Beijing, P.R. China.
authors.forename: Ming
authors.initials: M
authors.lastname: Fan
authors.affiliation: Department of Brain Protection and Plasticity, Institute of Basic Medical Sciences, Beijing, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Zhu
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D049109:Cell Proliferation; D018891:Dentate Gyrus / Q000378:metabolism; D015870:Gene Expression; D000860:Hypoxia / Q000378:metabolism; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008297:Male; D058953:Neural Stem Cells / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology; D010101:Oxygen Consumption; D016548:Prosencephalon / Q000378:metabolism; D051381:Rats; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D042461:Vascular Endothelial Growth Factor A