Background To recognize the biochemical adjustments induced by rest deprivation at a proteomic level, we compared the hippocampal proteome of rats possibly after 4 hours of rest or rest deprivation obtained simply by gentle handling. with an increase of proteins displaying higher abundance pursuing sleep. Of these, 16 proteins were also present in sufficient amount for a sequencing attempt and among the 13 identified proteins, the most relevant cellular function that was affected was cell metabolism. Conclusion At a proteomic level, short term sleep deprivation is characterized FLAG tag Peptide supplier by a higher expression of some proteins in the hippocampus and a lower abundance of other proteins in the adrenals (compared to normal sleep control). Altogether, this could indicate a general activation of a number of cellular mechanisms involved in the maintenance of wakefulness and in increased energy expenditure during sleep deprivation. These findings are relevant to suggested functions of sleep like energy repletion and the restoration of molecular stocks or a more global homeostasis of synaptic processes. Background Sleep is present in all vertebrate species studied so far suggesting that it might underpin one or several vital functions [1,2]. Sleep has been associated with functions as diverse as thermoregulation , energy conservation , immune defense , tissue restoration  and brain plasticity [7,8]. One way to approach the functions of sleep is to assess the effects of sleep deprivation on behavioral and physiological responses at the organism, tissue and cellular levels. Several studies addressing gene transcription through the sleep-wake cycle identified a number of genes that are differentially expressed during wakefulness and sleep (for reviews, see [9,10]). Physiological changes in cellular properties are eventually derived from gene transcription followed by gene translation and protein synthesis. In consequence, the characterization of protein changes that contribute to the cellular phenotype is an indispensable complement to genomic studies in understanding the link between cellular activity and behavior. To our knowledge, at the present time, only one proteomic study of the effect of sleep deprivation has been published. Using classical 2D-gel electrophoresis, Basheer et al. studied levels of protein expression in the rat basal forebrain after 6 hours of sleep deprivation by gentle handling . In this analysis, 89 spots showed more than a two-fold difference between 6 hours sleep-deprived rats and undisturbed sleeping controls. The fact that several identified proteins in their FLAG tag Peptide supplier study either belong to the cytoskeleton or are closely associated with synaptic function suggests that changes in synaptic transmission or plasticity may occur after 6 hours of sleep uvomorulin deprivation in a wake-promoting area of the rat basal forebrain. Since the hippocampus plays an important role in spatial memory , in humans  FLAG tag Peptide supplier as well as in rodents  and sleep deprivation is known to disturb the memory consolidation process , our objective was to identify changes in proteins levels happening in the rat hippocampus after the brief (4 hours) amount of rest or of total rest deprivation by mild handling. Because the hippocampus is also a target of stress hormones , we measured stress by classical stress indices  (stomach ulceration, adrenal hypertrophy and body weight loss). We also looked at the proteomic changes in the rat adrenals after 4 hours sleep deprivation since adrenals are physiologically affected by sleep deprivation . Results Sleep deprivation The activity of rats during 4 hours at the beginning of the light period was behaviorally scored. The mean duration of behaviorally scored sleep in undisturbed rats was 144.6 56.8 minutes. Sleep-deprived rats never slept during the 4 hours of sleep deprivation. Undisturbed rats were not awoken while sleep deprived rats were awoken 80.8 22.5 times during the 4 hours. Figure ?Figure11 shows, for consecutive 30-min intervals,.