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 Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>