ABSTRACT
The hippocampus makes new memories and is involved in mental cognition, and the hippocampal dentate gyrus (DG) is critical because neurogenesis, which occurs throughout life, occurs in the DG. We observed the differentiation of neuroblasts into mature neurons (granule cells) in the DG of C57BL/6 mice at various early postnatal (P) ages: P1, P7, P14, and P21 using doublecortin (DCX) immunohistochemistry (IHC) for neuroblasts and calbindin D-28k (CB) IHC for granule cells. DCX-positive cells decreased in the DG with age; however, CB+ cells increased over time. At P1, DCX and CB double-labeled (DCX+CB+) cells were scattered throughout the DG. At P7, DCX+CB+ cells (about 92% of CB+ cells) were seen only in the granule cell layer (GCL) of the dorsal blade. At P14, DCX+CB+ cells (about 66% of CB+ cells) were found in the lower half of the GCL of both blades. In contrast, at P21, about 18% of CB+ cells were DCX+CB+ cells, and they were mainly located only in the subgranular zone of the DG. These results suggest that the developmental pattern of DCX+CB+ cells changes with time in the early postnatal stages.
Subject(s)
Animals , Mice , S100 Calcium Binding Protein G , Cognition , Dentate Gyrus , Hippocampus , Immunohistochemistry , Neurogenesis , NeuronsABSTRACT
Earthworm extract has shown anticancer characteristics. In the present study, we examined the effect of chronic treatment with a high dose of earthworm (Eisenia andrei) extract (EE) on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus (DG) of 3-week-old mice using 5-bromo-2'-deoxyuridine (BrdU) and Ki-67 immunohistochemistry for cell proliferation and doublecortin (DCX) immunohistochemistry for neuroblast differentiation, respectively. BrdU-, Ki-67-, and DCX-immunoreactive cells were easily detected in the subgranular zone of the DG in vehicle (saline)-treated mice. However, BrdU-, Ki-67-, and DCX-immunoreactive cells in the 500 mg/kg EE-treated mice decreased distinctively compared to those in the vehicle-treated mice. In addition, brain-derived neurotrophic factor (BDNF) immunoreactivity and its protein level decreased markedly in the DG of the EE-treated group compared to those in the vehicle-treated group. These results indicate that chronic treatment with high dose EE decreased cell proliferation and neuroblast differentiation, and that BDNF immunoreactivity decreased in the DG of EE-treated mice.
Subject(s)
Animals , Mice , Brain-Derived Neurotrophic Factor , Bromodeoxyuridine , Cell Proliferation , Dentate Gyrus , Immunohistochemistry , Neurogenesis , OligochaetaABSTRACT
Neurogenesis is sustained throughout adulthood in the mammalian brain due to the proliferation and differentiation of adult neural progenitor cells found in the subventricular zone of the lateral ventricles and subgranular zone of the dentate gyrus. This review covers recent findings that elucidate different aspects of regulation of neurogenesis, including proliferation, migration and differentiation into mature neurons and functional integration into the existing neural circuits. Furthermore, this review also discusses the effects of pathological conditions on adult neurogenesis in both rodent models and human patients as well as some of the potential problems or limitations in neurogenesis research, which may shed some light on developing novel research strategies for replacement treatment of neurological disorders.
ABSTRACT
Objective The proliferation and differentiation of neural stem cells in the subventricular zone(SVZ) and subgranular zone(SGZ) have been observed in normal old rats or treated by middle cerebral artery occluded(MCAO) and sham operation respectively. Methods Old rats were used to make models of middle cerebral artery occluded(MCAO).By BrdU pulse labeling and immunohistochemical single staining,the change of the number of BrdU positive cells was observed in SVZ and SGZ of normal rats or cerebral ischemia rats after MCAO 3d,7d,14d,21d,28d and sham operation respectively.By BrdU accumulating label and immunohistochemical double staining,BrdU/NeuN and BrdU/GFAP positive cells were determined in SVZ and SGZ of aged rats after MCAO 14d. Results BrdU positive cells were found in bilateral SVZ and SGZ of all groups above mentioned.Compared with normal and sham groups,BrdU positive cells of SVZ and SGZ in cerebral ischemia rats were strikingly increased.BrdU positive cells reached the peaks in SVZ at 7d and in SGZ at 14d after MCAO.At 14d after MCAO,BrdU/NeuN(0.98%) or BrdU/GFAP(12.56%) double labled cells were observed in SVZ,but no double labled cell was observed in SGZ.Conclusion The focal cerebral ischemia markedly stimulated proliferation of neural stem cells in SVZ and SGZ in old rats,and some proliferative cells in SVZ can differentiate into neurons or glial cells.