Navigation Links
The hormone of darkness: melatonin could hurt memory formation at night
Date:11/15/2007

HOUSTON 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 teams findings in a paper titled Melatonin Suppresses Nighttime Memory Formation in Zebrafish, appearing Nov. 16 in Science, the worlds 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 antioxidants 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.

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. Theyre 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, Romans 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 hormones 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 melatonins antioxidant properties. Such benefits include fighting free radical damage to slow some forms of neurodegeneration, such as in Parkinsons and Alzheimers 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 hormones 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 melatonins antioxidant benefits while improving nighttime memory formation that is now inhibited by it.

Romans 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.


'/>"/>

Contact: Lisa Merkl
lkmerkl@uh.edu
713-743-8192
University of Houston  
Source:Eurekalert

Related medicine news :

1. Drop in breast cancer incidence linked to hormone use, not mammograms
2. Researchers develop long-lasting growth hormone
3. One of the Largest Post-WHI Physician Surveys Shows More Education is Needed: Patient Misinformation About Hormone Therapy Remains High
4. Less than one-third of women aware of landmark hormone therapy study, Stanford researcher finds
5. Most Women Unaware of Hormone Replacement Study
6. Survival data presented from phase II study of hormone-resistant prostate cancer patients
7. Hormone May Play Key Part in Creating Memories
8. Hormone Therapy for Prostate Cancer Linked to Heart Risks
9. Wyeth to Appeal Nevada Hormone Therapy Trial Verdict
10. New data on hormone therapy must lead to re-evaluation of official guidelines
11. From Hot Flashes to Breast Cancer: ZRT Labs Hormone Testing Catches On As Women Consider Safer, More Natural Options.
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
The hormone of darkness: melatonin could hurt memory formation at night
(Date:5/27/2016)... ... May 27, 2016 , ... Two director-level employees of ... Tribute to Women and Industry (TWIN) 2016 honorees. The award recognizes businesswomen who ... this year, Geri Boone, Director of the MLTSS (Managed Long-Term Services and Supports) Program ...
(Date:5/27/2016)... ... 27, 2016 , ... With over 60 percent of acute stroke survivors being ... product to aid in the rehabilitation process has steadily increased. Ekso Bionics had been ... hemiplegia due to stroke. , Ekso Bionics has now received clearance from the U.S. ...
(Date:5/27/2016)... ... May 27, 2016 , ... ... help educate the many who are unaware of the plight of aphasia. In ... run within the “Stroke Awareness” campaign. , The link between stroke and aphasia ...
(Date:5/27/2016)... ... , ... Aimed at nurses and employees in the health care world, this ... the nursing and health care industry. It also provides insight to the developing trends ... , As the nursing industry is coming out of one of the biggest recessions ...
(Date:5/26/2016)... (PRWEB) , ... May 26, 2016 , ... Despite last ... meeting, expect Janet Yellen and company to wait until March 2017 for an interest ... University’s J. Mack Robinson College of Business. , “The Federal Open Market Committee (FOMC) ...
Breaking Medicine News(10 mins):
(Date:5/27/2016)... Amarantus BioScience Holdings, Inc. (OTCQX: AMBS), ... Neurology and Orphan Diseases, today announced that President & CEO ... conferences: SeeThru Equity MicroCap Conference   ... City , NY When: Tuesday, May 31 st ... Where: Grand Hyatt Hotel, 109 East 42 nd ...
(Date:5/26/2016)... -- According to a new market report published ... Industry Analysis, Size, Share, Growth, Trends, and Forecast 2015 - ... valued at US$ 5.89 Bn in 2014 and is anticipated ... 2023 to reach US$ 7.99 Bn in 2023. ... free drug delivery devices and the market is estimated based ...
(Date:5/26/2016)... TARE (Transarterial Radio-embolization) Using ... and Overall Decreased Use of Hospital Resource ... specialist healthcare company, has today announced the publication ... of ISPOR (International Society for Pharmacoeconomics and Outcomes ... using yttrium-90 glass microspheres is associated with cost ...
Breaking Medicine Technology: