Glucose-regulated protein Grp78 affects characteristics of sleep and thermoregulation in rats

It was shown previously that sleep deprivation in representatives of warm-blooded animals evokes an elevation of the glucose-regulated protein 78 (Grp78) gene expression in the brain structures involved in the control of sleep and thermoregulation. However it is currently unknown what role the increased Grp78 expression plays in the mechanisms that maintain homeostasis of sleep and thermoregulation. Using electrophysiological methods, it has been shown in this study that microinjections of Grp78 into the third brain ventricle of Wistar rats evokes an increase mostly in deep non-rapid-eye-movement (NREM) sleep (due to a lengthening of the NREM sleep episodes) and a decrease in the amount of rapid-eye-movement sleep. The period of deep NREM sleep was accompanied by a reduced muscle contractile activity. Our results provide evidence that Grp78 is implicated in the molecular mechanisms of maintenance of deep NREM sleep typically accompanied by a decrease in muscle contractile activity.