Sleep deprivation suppresses neurogenesis in the adult hippocampus of rats

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Abstract
We reported previously that 96 h of sleep deprivation (SD) reduced cell proliferation in the dentate gyrus (DG) of the hippocampus in adult rats. We now report that SD reduces the number of new cells expressing a mature neuronal marker, neuronal nuclear antigen (NeuN). Rats were sleep‐deprived for 96 h, using an intermittent treadmill system. Total sleep time was reduced to 6.9% by this method in SD animals, but total treadmill movement was equated in SD and treadmill control (CT) groups. Rats were allowed to survive for 3 weeks after 5‐bromo‐2‐deoxyuridine (BrdU) injection. The phenotype of BrdU‐positive cells in the DG was assessed by immunofluorescence and confocal microscopy. After 3 weeks the number of BrdU‐positive cells was reduced by 39.6% in the SD group compared with the CT. The percentage of cells that co‐localized BrdU and NeuN was also lower in the SD group (SD: 46.6 ± 1.8% vs. CT: 71.9 ± 2.1, P < 0.001). The percentages of BrdU‐labeled cells co‐expressing markers of immature neuronal (DCX) or glial (S100‐β) cells were not different in SD and CT groups. Thus, SD reduces neurogenesis in the DG by affecting both total proliferation and the percentage of cells expressing a mature neuronal phenotype. We hypothesize that sleep provides anabolic or signaling support for proliferation and cell fate determination.