Animal study suggests inadequate sleep may exacerbate cellular aging in the elderly

Jun 27, 2008

Researchers at the University of Pennsylvania School of Medicine have shown that the unfolded protein response, which is a reaction to stress induced by sleep deprivation, is impaired in the brains of old mice.

The findings suggest that inadequate sleep in the elderly, who normally experience sleep disturbances, could exacerbate an already-impaired protective response to protein misfolding that happens in aging cells. "Protein misfolding and aggregation is associated with many diseases like Alzheimer's and Parkinson's," notes first author Nirinjini Naidoo, PhD, Assistant Professor in the Division of Sleep Medicine. The study appears in the June issue of the Journal of Neuroscience.

The unfolded protein response (UPR) is one part of the quality control system for monitoring protein synthesis in the endoplasmic reticulum, the cellular compartment where some proteins are made. In this study, researchers found that the UPR was activated in 10-week old, sleep-deprived mice, so that misfolded proteins did not accumulate in the endoplasmic reticulum of brain cells in the cerebral cortex. However, in two-year-old, sleep-deprived mice, the UPR failed to do its job and misfolded proteins clogged the endoplasmic reticulum. Old mice that were not stressed by sleep deprivation were shown to already have an impaired UPR.

Sleep in mice is characterized by short periods of inactivity throughout the day and night. On average, mice sleep approximately one hour for every two they are awake. In order to deprive mice of sleep, researchers constantly monitored and gently stroked the mice with a brush to disturb periods of inactivity.

At 3, 6, 9, or 12 hours of sleep deprivation, proteins were examined from the mouse brains. By six hours of sleep deprivation, young mice demonstrated that the UPR system was in place because protein synthesis was shut off by a chaperone protein called BiP/GRP78. In contrast, there was no BiP/GRP78 in old mice so protein synthesis continued.

Old mice also had less of the proteins that refold abnormal proteins than young mice, and old mice had more of the proteins that cause cell death than young mice. Thus, several processes are upset in old mouse brains by sleep deprivation, and the overall result is a further accumulation of misfolded proteins.

"We could speculate that sleep disturbance in older humans places an additional burden on an already-stressed protein folding and degradation system," says Naidoo.

Future studies will examine whether augmenting key protective proteins delays the effects of aging and reduces sleep disturbances.

Source: University of Pennsylvania School of Medicine

Explore further: Jobless and poor, Ghana's youth turn to selling blood

add to favorites email to friend print save as pdf

Related Stories

Engineering light-controlled proteins

Jul 03, 2014

(Phys.org) —A University of Wyoming professor has engineered proteins that can be activated by near-infrared light as a way to control biological activities in deep tissues of small mammals.

Chrono, the last piece of the circadian clock puzzle?

Apr 15, 2014

All organisms, from mammals to fungi, have daily cycles controlled by a tightly regulated internal clock, called the circadian clock. The whole-body circadian clock, influenced by the exposure to light, dictates the wake-sleep ...

Mouse groups reveal complex relationships

Sep 03, 2013

A common belief is that our modern, stimulation-filled environment encourages individualistic behavior (or anti-social behavior, depending on one's point of view), while simpler surroundings give rise to ...

Higgs Boson tops journal Science's top 10 of 2012

Dec 21, 2012

The discovery of the Higgs Boson, an invisible particle that explains the mystery of mass, leads a list of the top 10 scientific advances of 2012 released Thursday by the US journal Science.

Recommended for you

The human race evolved to be fair for selfish reasons

Sep 19, 2014

"Make sure you play fairly," often say parents to their kids. In fact, children do not need encouragement to be fair, it is a unique feature of human social life, which emerges in childhood. When given the o ...

Non-stop PET/CT scan provides accurate images

Sep 18, 2014

Siemens is improving PET/CT imaging and data quality while reducing radiation exposure. The Biograph mCT Flow PET/CT scanner is a new positron emission tomography/computed tomography (PET/CT) system that, ...

User comments : 0