Effects Of Sleep Deprivation On The Expression Of Heat Shock Protein70 And Neuronal Cytoskeleton Protein In Rat Brain

The harmful effects of sleep deprivation have been recognized for some time in humans. Short periods of sleep loss results in significant cognitive deficits while long term disturbances in sleep have been associated with reduced life span. In rats, prolonged sleep deprivation leads to a syndrome characterized by increased food intake, weight loss, increased energy expenditure, progressive decline in body temperature, and eventually death. However, histological studies of sleep deprivation animal did not find any neuronal degeneration or apoptosis. Damage of organelles including mitochondria, Golgi apparatus, ribosomes, nucleoli was not found in brain cells after sleep deprivation either.To further investigate the possible mechanisms of sleep deprivation, we observed the expression pattern of heat shock protein70(HSP70), microrube-associated protein 2 (MAP2) and neurofilament(NF) after rapid eye movement(REM) sleep deprivation. The experiments were carried out on adult male Wistar rats, which had been deprived of paradoxical sleep according to the modified multiple platform method (MMPM) by Deborah Suchecki. Immunohistochemistry, western blot and electron microscopic technique were used in this study. The results showed that the expression of HSP70 increased significantly in the rat cerebral cortex and hippocampual CA1, CA3 and dentate gyrus after 1 day REM sleep deprivation. The expression of MAP2 and NF decreased in the same areas after 5 day REM sleep deprivation. The western blot results supported these observations. Electron microscopic examination indicated that loosening and deletion of neurofilament appeared in the axons after 5 day REM sleep deprivation, consistent with results obtained by immunohistochemistry and westernblot. The increase expression of HSP70 might be a neuroprtective response to insults induced by short term sleep deprivation. Stress response genes over expression might contribute to one of this homeostatic reaction. The decrease of NF might be related to the functional deficits of central nerve system after sleep deprivation, such as memory, cognition, skill learning etc.