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    Changes of nNOS positive neurons in hippocampus and memory consolidation after paradoxical sleep deprivation in rats

    ZHANG Fuª²Kang, HOU Yiª²Ping, SONG Yanª²Feng, LIU Xiangª²Wen, WANG Deª²Gui

    Department of Anatomy, School of Basic Medicine, Lanzhou University, Lanzhou 730000, China

    ¡¾Abstract¡¿ AIM: To study the changes of memory processes and consolidation during paradoxical sleep in rats and to observe the alteration of neuronal nitric oxide synthase immunoreactivity (nNOSª²IR) neurons in hippocampus after paradoxical sleep deprivation. METHODS: Aradoxical sleep deprivation was performed using the "lower pot technique" The control groups (CC), tank control groups(TC) and paradoxical sleep deprivation groups(PSD) were tested in Morris Water Maze. At the end of the experiment, the animals were sacrificed under chloral hydrate anesthesia (0.4 g/kg) by intraª²aortic perfusion of a fixative solution. Coronal sections were cut at 25 ¦Ìm thickness on a freezing microtome and up to five series of adjacent sections were collected for nNOS immunohistochemical processing using streptavidinª²biotinª²peroxidase complex technique (SABC technique). RESULTS: The memory consolidation in PSD 24 h, PSD 48 h and PSD 72 h rats declined significantly compared with that in TC 24, 48, 72 h as well as CC 24, 48, 72 h rats (P<0.05), indicating that PSD caused a significant impairment in reference memory. The nNOSª²expressing cells in hippocampus of PSD 24, 48, 72 h rats were significantly fewer than those in TC 24, 48, 72 h as well as CC 24, 48, 72 h rats (P<0.05). CONCLUSION: ¢ÙParadoxical sleep deprivation may cause a disturbance of memory processes and consolidation and paradoxical sleep is associated with memory. ¢ÚThe nNOSª²IR neurons in hippocampus formation decrease in PSD groups compared with those in CC and TC groups. nNOS in hippocampus may play a key role during paradoxical sleep and spatial memory. ......