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 New yeast species discovered in Braunschweig, Germany
13.12.2019 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH

nachricht Saliva test shows promise for earlier and easier detection of mouth and throat cancer
13.12.2019 | Elsevier

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Virus multiplication in 3D

Vaccinia viruses serve as a vaccine against human smallpox and as the basis of new cancer therapies. Two studies now provide fascinating insights into their unusual propagation strategy at the atomic level.

For viruses to multiply, they usually need the support of the cells they infect. In many cases, only in their host’s nucleus can they find the machines,...

Im Focus: Cheers! Maxwell's electromagnetism extended to smaller scales

More than one hundred and fifty years have passed since the publication of James Clerk Maxwell's "A Dynamical Theory of the Electromagnetic Field" (1865). What would our lives be without this publication?

It is difficult to imagine, as this treatise revolutionized our fundamental understanding of electric fields, magnetic fields, and light. The twenty original...

Im Focus: Highly charged ion paves the way towards new physics

In a joint experimental and theoretical work performed at the Heidelberg Max Planck Institute for Nuclear Physics, an international team of physicists detected for the first time an orbital crossing in the highly charged ion Pr⁹⁺. Optical spectra were recorded employing an electron beam ion trap and analysed with the aid of atomic structure calculations. A proposed nHz-wide transition has been identified and its energy was determined with high precision. Theory predicts a very high sensitivity to new physics and extremely low susceptibility to external perturbations for this “clock line” making it a unique candidate for proposed precision studies.

Laser spectroscopy of neutral atoms and singly charged ions has reached astonishing precision by merit of a chain of technological advances during the past...

Im Focus: Ultrafast stimulated emission microscopy of single nanocrystals in Science

The ability to investigate the dynamics of single particle at the nano-scale and femtosecond level remained an unfathomed dream for years. It was not until the dawn of the 21st century that nanotechnology and femtoscience gradually merged together and the first ultrafast microscopy of individual quantum dots (QDs) and molecules was accomplished.

Ultrafast microscopy studies entirely rely on detecting nanoparticles or single molecules with luminescence techniques, which require efficient emitters to...

Im Focus: How to induce magnetism in graphene

Graphene, a two-dimensional structure made of carbon, is a material with excellent mechanical, electronic and optical properties. However, it did not seem suitable for magnetic applications. Together with international partners, Empa researchers have now succeeded in synthesizing a unique nanographene predicted in the 1970s, which conclusively demonstrates that carbon in very specific forms has magnetic properties that could permit future spintronic applications. The results have just been published in the renowned journal Nature Nanotechnology.

Depending on the shape and orientation of their edges, graphene nanostructures (also known as nanographenes) can have very different properties – for example,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The Future of Work

03.12.2019 | Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

 
Latest News

Supporting structures of wind turbines contribute to wind farm blockage effect

13.12.2019 | Physics and Astronomy

Chinese team makes nanoscopy breakthrough

13.12.2019 | Physics and Astronomy

Tiny quantum sensors watch materials transform under pressure

13.12.2019 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>