Navigation Links
Support cells, not neurons, lull the brain to sleep
Date:1/28/2009

Brain cells called astrocytes help to cause the urge to sleep that comes with prolonged wakefulness, according to a study in mice, funded by the National Institutes of Health. The cells release adenosine, a chemical known to have sleep-inducing effects that are inhibited by caffeine.

"Millions of Americans suffer from disorders that prevent a full night's sleep, and others from pilots to combat soldiers have jobs where sleepiness is a hazard. This research could lead to better drugs for inducing sleep when it is needed, and for staving off sleep when it is dangerous," says Merrill Mitler, Ph.D., a program director with the NIH's National Institute of Neurological Disorders and Stroke (NINDS).

The study appears Jan. 29, 2009 in Neuron, and was funded by NINDS, the National Institute of Mental Health (NIMH) and the National Institute on Aging (NIA), all part of NIH. It is the result of a collaboration among Michael Halassa, M.D., and Philip Haydon, Ph.D., at Tufts University School of Medicine in Boston and Marcos Frank, Ph.D., and Ted Abel, Ph.D. at the University of Pennsylvania School of Medicine in Philadelphia.

Although the exact purpose of sleep is unknown, everyone seems to need it, and some research suggests that it strengthens memories by adjusting the connections between neurons. As the waking hours tick by, all animals experience an increasing urge to sleep, known as sleep pressure. If sleep is delayed, a deep, long sleep usually follows as the body's means of compensating.

Prior studies pointed to adenosine as a trigger for sleep pressure. The chemical accumulates in the brain during waking hours, eventually helping to stimulate the unique patterns of brain activity that occur during sleep.

Dr. Halassa says that the results of the new study show that "adenosine from astrocytes clearly regulates sleep pressure." He notes that this is the first time a non-neuronal cell within the brain has been shown to influence behavior. Unlike neurons, astrocytes do not fire electrical spikes, and they are often described as support cells.

In experiments on mice, Dr. Halassa and his colleagues used a genetic switch, called the dnSNARE transgene, to block the release of adenosine and other chemicals from astrocytes. The researchers then deprived the mice of sleep for short periods, and evaluated them with behavioral tests and with electroencephalography (EEG), a means of recording brain activity.

Mice subjected to the genetic blockade exhibited less sleep pressure than control mice. Following sleep deprivation, they did not need as much compensatory sleep, and during the early phases of sleep, they had patterns of brain activity consistent with low sleep pressure. When they were evaluated with a memory test, they performed as if their sleep had been undisturbed.

The researchers observed similar results when they used certain compounds to block the effects of adenosine on neurons. Neurons have several types of cell-surface receptors that enable them to respond to adenosine, but only pharmacological blockade of the A1 type of receptor was effective. That result shows that adenosine acts through the A1 receptor to produce sleep pressure.

Taken together, the results hint at the possibility of new drugs that could increase or decrease sleep pressure as necessary. The best available sleep aids tend to be effective at inducing sleep, but not effective at keeping it steady throughout the night. Meanwhile, the most commonly used stimulant, caffeine, acts on multiple types of adenosine receptors, and can affect sleep patterns even when it is consumed in the morning. Drugs that target astrocytes or the A1 receptors on neurons might be more effective at fine-tuning the urge to sleep, the study authors say.

The dnSNARE mice also will prove useful for answering some long-standing questions about sleep, experts say. For instance, since the dnSNARE mice are resistant to sleep deprivation, they might help explain why some people need less sleep than others. Further studies of the dnSNARE mice could help reveal why people need sleep at all.

This research "puts astrocytes at the heart of why we sleep," says Dr. Halassa.


'/>"/>

Contact: Daniel Stimson
stimsond@ninds.nih.gov
301-496-5751
NIH/National Institute of Neurological Disorders and Stroke
Source:Eurekalert

Related medicine news :

1. Purkinje Announces EMR Promotions in Support of National Healthcare Reform Initiatives
2. Call- Shadow IP Call Management Software, V.5. Now 64 bit with SIP and Enhanced Platform Support
3. Manhattan Research Survey Finds That Physicians Overwhelmingly Support Commercially-Funded Continuing Medical Education
4. Lance Armstrong Foundation Selects Ogilvy Public Relations Worldwide to Support the LIVESTRONG Global Cancer Campaign
5. Impac Software Announces Clinical Release of RapidArc Support
6. Technology Leaders Call on Congress to Support Investments in Digital Infrastructure as Part of Economic Stimulus and Recovery Plan
7. Grassroots Group Gets Travel Advantage Network Support
8. Developing countries need support to ethically conduct unlinked anonymous HIV testing
9. The Quantum Group Announces Support of Technology Bill Before Congress
10. Seattle Reproductive Medicine Study Investigates Newly Formulated Medications for Luteal Support in IVF
11. National Council of Legislators From Gaming States Adopts Resolution Supporting 100% Smokefree Gaming Venues
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/24/2017)... ... ... “The Adventures of Joey, The Dog Who Barks at Puddles”: a boisterous story about ... as God intended. “The Adventures of Joey, The Dog Who Barks at Puddles” is ... for writing, especially about truth and human behavior. , Published by Christian Faith Publishing, ...
(Date:3/23/2017)... , ... March 23, 2017 , ... A recent report ... entry into teacher preparation programs. The NCTQ report suggests, based on a review of ... would significantly improve teacher quality in the U.S. It argues that this higher bar ...
(Date:3/23/2017)... ... March 23, 2017 , ... ... to their communities, 16 more public health departments have been awarded national accreditation ... another 4.5 million people into the expanding network of communities across the nation ...
(Date:3/23/2017)... ... March 23, 2017 , ... PAINWeekEnd (PWE) Oklahoma City, on ... Avenue, will be an educational and exciting program providing busy clinicians and allied ... chronic pain. , Oklahoma is in a healthcare crisis. The state ranks 46th ...
(Date:3/23/2017)... ... 23, 2017 , ... The MBI “Hall of Fame” recognizes the contributions of those whose careers ... impact on the careers of all others involved. , On Monday, March 21st, ... MBI’s Hall of Fame. The induction took place during the World of Modular – ...
Breaking Medicine News(10 mins):
(Date:3/24/2017)... Wash. , March 23, 2017  Mirabilis ... of advanced medical technology for non-invasive surgery, announced ... Mirabilis System for treatment of uterine fibroids throughout ... it had received approval from the US Food ... of the Mirabilis System in the United States.  ...
(Date:3/23/2017)... Research and Markets has announced the addition of the ... 2025" report to their offering. ... The Global Cryostat Market is poised to ... to reach approximately $3.5 billion by 2025. This industry ... segments on global as well as regional levels presented in the ...
(Date:3/23/2017)... March 23, 2017  Transportation Insight, a multi-modal lead ... supply chain management firm with expertise serving clients in ... Rick Zaffarano was named a 2017 ... Chain by the only publication exclusively dedicated to covering ... chain. "Rick has brought to Transportation Insight ...
Breaking Medicine Technology: