Chaperone Hsp70 is involved in the molecular mechanisms of slow wave sleep regulation

Hsp70 ameliorates sleep deprivation-induced anxiety-like behavior and cognitive impairment in mice

BACKGROUND

Many neurobehavioral processes, including psychomotor, cognitive, and affection are negatively impacted by sleep deprivation (SD), which may be harmful to a person's physical and mental health. Heat shock proteins (Hsps) have been demonstrated to play a protective role in a number of neurodegenerative diseases and are essential for maintaining intracellular protein homeostasis, but their roles in SD remain elusive.

METHODS

A mouse SD model was constructed using a modified multi-platform water environment method. The cognitive function was tested by novel object recognition test and Y-maze test, and anxiety-like behaviors were assessed by open field test (OFT). Protein expression was determined by Western blotting assay and ELISA assay.

RESULTS

We found that SD could profoundly enhance anxiety levels and impair cognitive function in mice. SD also reduced the expression levels of p-cAMP-response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) and increased microglial activation and neuroinflammatory response in the hippocampus of mice. The intranasal injection of human recombinant Hsp70 protein could alleviate SD-induced anxiety and cognitive impairment, as well as restore pCREB and BDNF levels and reduce microglia-induced neuroinflammation in the hippocampus of SD mice.

CONCLUSIONS

Hsp70 treatment might serve as a potential treatment for mitigating SD-related unfavorable symptoms.

Chaperone Hsp70 (HSPA1) Is Involved in the Molecular Mechanisms of Sleep Cycle Integration

The molecular mechanisms of sleep cycle integration at the beginning and the end of the inactive period are not clear. Sleep cycles with a predominance of deep slow-wave sleep (SWS) seem to be associated with accelerated protein synthesis in the brain. The inducible Hsp70 chaperone corrects protein conformational changes and has protective properties. This research explores (1) whether the Hspa1 gene encoding Hsp70 protein activates during the daily rapid-eye-movement sleep (REMS) maximum, and (2) whether a lower daily deep SWS maximum affects the Hspa1 expression level during the subsequent REMS. Combining polysomnography in male Wistar rats, RT-qPCR, and Western blotting, we reveal a three-fold Hspa1 upregulation in the nucleus reticularis pontis oralis, which regulates REMS. Hspa1 expression increases during the daily REMS maximum, 5-7 h after the natural peak of deep SWS. Using short-term selective REMS deprivation, we demonstrate that REMS rebound after deprivation exceeds the natural daily maximum, but it is not accompanied by Hspa1 upregulation. The results suggest that a high proportion of deep SWS, usually observed after sleep onset, is a necessary condition for Hspa1 upregulation during subsequent REMS. The data obtained can inform the understanding of the molecular mechanisms integrating SWS and REMS and key biological function(s) of sleep.