Aging does not alter the number or phenotype of putative stem/progenitor cells in the neurogenic region of the hippocampus.
To investigate whether dramatically waned dentate neurogenesis during aging is linked to diminution in neural stem/progenitor cell (NSC) number, we counted cells immunopositive for Sox-2 (a putative marker of NSCs) in the subgranular zone (SGZ) of young, middle-aged and aged F344 rats. The young SGZ comprised approximately 50,000 Sox-2+ cells and this amount did not diminish with aging. Quantity of GFAP+ cells and vimentin+ radial glia also remained stable during aging in this region. Besides, in all age groups, analogous fractions of Sox-2+ cells expressed GFAP (astrocytes/NSCs), NG-2 (oligodendrocyte-progenitors/NSCs), vimentin (radial glia), S-100beta (astrocytes) and doublecortin (new neurons). Nevertheless, analyses of Sox-2+ cells with proliferative markers insinuated an increased quiescence of NSCs with aging. Moreover, the volume of rat-endothelial-cell-antigen-1+ capillaries (vascular-niches) within the SGZ exhibited an age-related decline, resulting in an increased expanse between NSCs and capillaries. Thus, decreased dentate neurogenesis during aging is not attributable to altered number or phenotype of NSCs. Instead, it appears to be an outcome of increased quiescence of NSCs due to changes in NSC milieu.
Hattiangady
Bharathi
B
Department of Surgery (Neurosurgery), Duke University Medical Center, Durham, NC 27710, United States.
Shetty
Ashok K
AK
D000375:Aging / Q000502:physiology*; D000818:Animals; D001253:Astrocytes / Q000502:physiology; D001973:Bromodeoxyuridine / Q000378:metabolism; D002196:Capillaries / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D049109:Cell Proliferation; D002552:Cerebral Ventricles / Q000166:cytology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D000089662:Doublecortin Protein; D024002:HMGB Proteins / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D011938:Rec A Recombinases / Q000378:metabolism; D055748:SOXB1 Transcription Factors; D013234:Stem Cells / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
D004268:DNA-Binding Proteins; C000714848:Dcx protein, rat; D000089662:Doublecortin Protein; D024002:HMGB Proteins; D019394:Ki-67 Antigen; D009419:Nerve Tissue Proteins; D055748:SOXB1 Transcription Factors; C527784:Sox2 protein, rat; D014157:Transcription Factors; D014746:Vimentin; D011938:Rec A Recombinases; D001973:Bromodeoxyuridine