Project Details
Description
PROJECT SUMMARY
Insufficient sleep, sleep disorders, and resulting problems with health and cognition are increasingly common
in the United States. Many sleep disorders may be associated with abnormal sleep homeostasis: an innate
regulatory process that balances sleep need, sleep intensity, and sleep amount as a function of prior time
spent awake. Sleep homeostasis requires a feedback circuit to maintain the system within defined limits.
However, the cellular components and protein signaling pathways of this feedback circuit remain incompletely
defined. Our understanding of sleep homeostasis thus far is primarily based on the study of neurons, but I
showed that non-neuronal cells (i.e. astrocytes) also play a role. I posit that the homeostatic feedback circuit
includes a neuronal waking signal that reflects sleep need and an astroglial integrator of the neuronal waking
signal. I propose that the wake-promoting neurotransmitter noradrenaline (NA) is a candidate for the neuronal
waking signal that interacts with astrocytes. I further propose that calcium (Ca2+) is the astroglial integrator of
sleep need because 1) NA increases astroglial Ca2+ activity and 2) I showed that astroglial Ca2+ plays a role in
sleep homeostasis. My overall hypothesis is that wake-promoting neurons increase astroglial Ca2+ signaling
during elevated sleep need. I will test this hypothesis in two AIMS: 1) Determine how NA impacts astroglial
Ca2+ dynamics before, during, and after sleep deprivation (SD); 2) Determine how sleep loss impacts astroglial
protein signaling. For AIM 1, I will use a multifaceted approach to optogenetically inhibit or stimulate NA
neurons while imaging Ca2+ dynamics in adjacent astrocytes and recording electroencephalographic brain
state activity in freely behaving mice. Optogenetics, Ca2+ imaging, and electroencephalographic recordings will
occur simultaneously under baseline conditions and during SD & recovery. Using this multimodal approach, I
can temporally register cell-type specific neuronal activity and astroglial Ca2+ dynamics within distinct arousal
states in freely behaving mice. For AIM 2, I will determine which astroglial proteins respond to changes in sleep
need. I will use ultra-performance liquid chromatography-tandem mass spectrometry to quantify astroglial
proteins from rested and SD mice using targeted and untargeted proteomics. Targeted proteomics will include
NA- & Ca2+-related signaling proteins as well as synaptic, metabolic, and gap junction proteins because these
proteins are implicated in sleep homeostasis. I will also determine the phosphorylation status of these proteins
because phosphorylation status changes with sleep need and is an important post-translational modification in
astrocytes. Astrocytes will be isolated from brains of wild type mice and mutant mice with reduced astroglial
Ca2+ signaling. In this way, I can determine which astroglial proteins are 1) responsive to changes in sleep
need and 2) Ca2+-dependent. The proposed studies use innovative methods to define biological substrates of
sleep homeostasis. These findings, in turn, will further characterize the contribution of non-neuronal cells in the
regulation of sleep-wake behavior and will expand our understanding of physiological and disordered sleep.
Status | Finished |
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Effective start/end date | 09/1/23 → 04/30/24 |
Funding
- National Institute of Neurological Disorders and Stroke: $249,000.00
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