Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The hormone of darkness: melatonin could hurt memory formation at night

19.11.2007
Professor Gregg Roman and UH team discover nighttime 'malfunction' of biological clock

What do you do when a naturally occurring hormone in your body turns against you? What do you do when that same hormone – melatonin – is a popular supplement you take to help you sleep? A University of Houston professor and his team of researchers may have some answers.

Gregg W. Roman, assistant professor in the department of biology and biochemistry at UH, describes his team’s findings in a paper titled “Melatonin Suppresses Nighttime Memory Formation in Zebrafish,” appearing Nov. 16 in Science, the world’s leading journal of original scientific research, global news and commentary.

Frequently called “the hormone of darkness,” melatonin is a hormone the body produces that may regulate patterns of sleeping and awakening in humans. In almost all organisms tested, this antioxidant’s natural levels are high during the night and low during the day. In addition to what the body produces naturally, many people also take melatonin supplements to fight jet lag, balance out seasonal affect disorder and regulate nighttime dementia.

... more about:
»Melatonin »formation »hormone »memories »night

Roman says, however, that melatonin could actually be hurting you at night, finding in a study with zebrafish (Danio rerio) that melatonin directly inhibits memory formation.

“This work is about the mechanism by which the biological clock controls the formation of new memories,” Roman said. “We were interested in the circadian control – the day-night cycle control – of learning and memory formation. We found zebrafish are capable of learning very well during their active phase during the day, but learn very poorly at night during their sleep or quiet phase.”

The experiments were performed using zebrafish for several reasons. They’re small and breed in large numbers (thereby being less expensive to use), and they are diurnal, having the same activity rhythms as people. Zebrafish are most active during the day and less active at night, whereas many other vertebrate model systems, such as rodents, are nocturnal. Roman reasons that if you are interested in how the biological clock regulates cognitive function in humans, you should use a model system that reacts to the clock the same way people do.

More than two years worth of work, including the discovery that the ability to learn and remember was controlled by an endogenous (or internal) clock originating within the zebrafish, led Roman and his colleagues to hypothesize that melatonin may be responsible for poor learning and memory formation during the night. In order to test whether melatonin was involved in inhibiting nighttime learning and memory formation, they treated the zebrafish during the day with this hormone to see how the fish performed. Interestingly, melatonin failed to affect learning, but dramatically inhibited the formation of new memories, with the melatonin-treated fish resembling fish trained during the night in a test for 24-hour memory.

“The next step was to inhibit melatonin signaling during the night with a melatonin receptor antagonist and test for effects on memory formation,” Roman said. “It was tremendous – the results were, excuse the expression, like night and day. We saw dramatic improvements in nighttime memory formation by inhibiting melatonin signaling, indicating that the reason the zebrafish did not form memories at night was because of the melatonin hormone.”

Next, with the pineal gland being the primary source of melatonin in fish and in people, Roman’s student Oliver Rawashdeh removed this gland from the fish and found they could now form memories at high levels even during the night. Removing this melatonin-producing gland allowed the researchers to alleviate the hormone’s negative side effects, further demonstrating that melatonin inhibits the formation of new memories during the night.

With these findings, Roman hopes to be able to retain the beneficial effects of melatonin’s antioxidant properties. Such benefits include fighting free radical damage to slow some forms of neurodegeneration, such as in Parkinson’s and Alzheimer’s diseases, and stopping DNA damage, which has potential to act as a preventative against cancer. And, since the positive antioxidant effect is direct and independent of receptor signaling, there is hope that removing the melatonin receptor signaling will combat only this hormone’s negative effects on cognitive function.

Additionally, Roman said that inhibiting melatonin signaling with receptor antagonists may help with a large number of nighttime cognitive tasks, helping such people as students studying for finals, airplane pilots, ER physicians and night-shift workers. Roman also thinks that a natural role of melatonin may be to facilitate the storage of memories made during the day and that more studies are required to understand the ultimate role melatonin has in memory formation.

“The value of melatonin as a supplement is largely due to its antioxidant properties,” Roman said. “The use of melatonin receptor antagonists will not affect this attribute, but may alleviate an important side effect on nighttime cognitive function.”

In other words, a ‘best of both worlds’ scenario could result, taking advantage of melatonin’s antioxidant benefits while improving nighttime memory formation that is now inhibited by it.

Roman’s team at UH for this breakthrough study includes Gregory M. Cahill, associate professor of biology and biochemistry, and two of their students and research assistants, Oliver Rawashdeh and Nancy Hernandez de Borsetti.

Lisa Merkl | EurekAlert!
Further information:
http://www.uh.edu
http://www.uh.edu/news-events/

Further reports about: Melatonin formation hormone memories night

More articles from Life Sciences:

nachricht New gene potentially involved in metastasis identified
26.03.2019 | Institute of Science and Technology Austria

nachricht Decoding the genomes of duckweeds: low mutation rates contribute to low genetic diversity
26.03.2019 | Westfälische Wilhelms-Universität Münster

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New gene potentially involved in metastasis identified

Gene named after Roman goddess Minerva as immune cells get stuck in the fruit fly’s head

Cancers that display a specific combination of sugars, called T-antigen, are more likely to spread through the body and kill a patient. However, what regulates...

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Listening to the quantum vacuum

26.03.2019 | Physics and Astronomy

The struggle for life in the Dead Sea sediments: Necrophagy as a survival mechanism

26.03.2019 | Earth Sciences

Mangroves and their significance for climate protection

26.03.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>