Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biological clock more influenced by temperature than light

15.07.2003


’The brain’s Timex’



Getting over jet lag may be as simple as changing the temperature --your brain temperature, that is.

That’s a theory proposed by Erik Herzog, Ph.D. assistant professor of biology in Arts & Sciences at Washington University in St. Louis. Herzog has found that the biological clocks of rats and mice respond directly to temperature changes.


Biological clocks, which drive circadian rhythms, are found in almost every living organism. In mammals, including humans, these clocks are responsible for 24-hour cycles in alertness and hormone levels, for instance. The control panel for these daily rhythms is the suprachiasmatic nucleus (SCN), otherwise known as "the brain’s Timex." The SCN, located above the roof of the mouth in the hypothalamus, is normally synchronized to local time by light signals carried down the optic nerves. Herzog worked directly with mice SCN cells located in vitro, grown in a dish.

"We found that we can rapidly change the phase of the pacemaker. We can shift its timing to a new time zone," said Herzog. "This paper shows for the first time that we can take control of the clock in a dish. We can tell it what time we want it to think it is."

Herzog’s findings were recently published in the Journal of Neurophysiology.. His work was funded by the National Institute of Mental Health.

The findings have significant future implications. If brain temperature can be controlled, travellers might never have to deal with jet lag again. Shifting to a new time zone might be accomplished with relative ease.

Herzog says that brain temperature is relatively immune to environmental temperature, but can be affected by bursts of physical activity, fever, nursing, or a dose of aspirin or melatonin, a drug already used to lessen the effects of jet lag.

In his study, Herzog first needed to establish that the SCN would function normally over a wide range of constant temperatures. He tested the cells in a range from 24 C to 370C. With each change in temperature, the SCN cells continued to operate like clockwork.

"Just like a good watch, the SCN needs to be accurate over a range of temperatures. Your wristwatch would be of no use to you if it sped up every time it became warm. Biological clocks work the same way. Amazingly enough, the SCN can oscillate over a wide range of temperatures."

But Herzog was keeping the cells in constant temperature and, he noted, this is not the way your brain really works. Normally, brain temperature fluctuates by about 1.50C every day. Temperature is at its minimum at daybreak, at its maximum during mid-day. This fluctuation exists even in the absence of any environmental cues, such as light and dark. "If you lived in a cave," Herzog notes, "you’d still have a daily rhythm in temperature.

"So we asked the question if that cycling of temperature, if that 1.50C, would have any effect on the pacemaking of the SCN." The answer was a resounding yes.

Herzog simply warmed the isolated SCN during the day and cooled it during the night, reversing the rat’s normal daily fluctuation. He found that he could change the time at which the SCN "peaked."

"It shows that the SCN synchronized to the temperature cycle. The temperature cycle entrained it. We fooled the clock by giving it a novel daily schedule, saying ’This isn’t the end of the day. This is morning.’"

Herzog’s research also sought to disprove the notion put forth in 1998 that shining light on the backs of the knees would be enough to adjust circadian rhythm to a new time zone.

The idea was that by sensing light at the appropriate time people can become synchronized to a new time zone. So Herzog wanted to know: Does the SCN by itself have any light sensitivity?

"We took the SCN out of the animal, put it in a dish, and exposed it to light at night and dark during the day. We asked: does it synchronize to that light-dark schedule? The answer was no." The human biological clock requires the signals from eyes to synchronize to the local light cycle.

Taken together, Herzog’s findings indicate that, to avoid jet lag on our next trip to Paris, we should be sure to see the dawn while keeping our brains cool. Future work might lead to a better understanding of what changes brain temperature and why.

Tony Fitzpatrick | EurekAlert!
Further information:
http://www.wustl.edu/

More articles from Life Sciences:

nachricht When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie

nachricht WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>