Sleep deprivation reduces proliferation of cells in the dentate gyrus of the hippocampus in rats

The dentate gyrus (DG) of the adult hippocampus gives rise to progenitor cells, which have the potential to differentiate into neurons. To date it is not known whether sleep or sleep loss has any effect on proliferation of cells in the DG. Male rats were implanted for polysomnographic recording, and divided into treadmill sleep-deprived (SD), treadmill control (TC) and cage control (CC) groups. SD and TC rats were kept for 96 h on a treadmill that moved either for 3 s on/ 12 s off (SD group) or for 15 min on/60 min off (TC group) to equate total movement but permit sustained rest periods in TC animals. To label proliferating cells the thymidine analogue 5-bromo-2'deoxyuridine (BrdU) was injected after the first 48 h of the experimental procedure in all groups (50 mg kg(-1), I.P.). The percentage of time awake per day was 93.2% in the SD group vs. 59.6% in the TC group and 49.9% in the CC group (P < 0.001). Stereological analysis showed that the number of BrdU-positive cells in the DG of the dorsal hippocampus was reduced by 54% in the SD group in comparison with the TC and by 68% in comparison with the CC group. These results suggest that sleep deprivation reduces proliferation of cells in the DG of the dorsal hippocampus.