Nighttime 'Malfunction' Of Biological Clock Discovered

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

Gregg W. Roman, assistant professor in the department of biology and biochemistry at UH, his team describes the findings in a paper titled "Melatonin Suppress night operation Memory Formation in the Zebrafish" published November 16 in Science , in the World Wide leading scientific journal of global news and commentary.

often called "hormone of darkness," Melatonin is a hormone the body produces, which may regulate sleep patterns and wakes up in the people. In almost all organisms tested, this means the natural antioxidants are high during the night and during the day lower. In addition to what the body produces naturally many people also Melatonin supplements to combat Jet Lag, offset seasonal affect disorder and regulate nighttime dementia.

Roman says that melatonin may actually hurt you in the night, to be found in a study of zebrafish (Danio rerio) that directly inhibit melatonin memory formation.

"This work is about the mechanism by which the biological clock controls the formation of new memories," said Roman. "We were interested in the circadian control -- the day the night cycle control -- of learning and memory formation. We have noted, zebra fish are capable of learning very well during its active phase during the day, but to learn a bad at night during sleep or quiet phase. "

The experiments were with zebra fish for several reasons. They are small and breed in large numbers (and therefore less expensive to use), and they are daily values, the same as human activity rhythms. Zebra fish are most active during the day and less active at night, while many other vertebrate animal models, such as rodents, the nightly. Roman reasons, if you are interested in how the biological clock governs cognitive functions in humans, you should create a system that the model is sensitive 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 one of endogenous (or internal) clock originated in the zebrafish, led Roman and his colleagues on the hypothesis that melatonin may be responsible for poor learning and memory formation in the night. To test whether melatonin has been involved in the inhibition of the night learning and memory formation, which they treated zebra fish during the day, with this hormone, to see how the fish. It is interesting that melatonin not affect learning, but significantly impeded the formation of new memories, the melatonin-treated fish with fish is similar trains during the night in a test for 24 hours memory.

"The next step was signaling inhibits melatonin during the night with a melatonin receptor antagonist and testing for the effects on memory formation," said Roman. "It was huge -- the results were, excuse the expression, like day and night. We saw dramatic improvements in the nightly memory inhibition of melatonin signaling, indicating that the reason the zebrafish was not in the form memories of the night because of the hormone melatonin. "

Continue with the pineal gland, the main source of melatonin in fish and in people, Roman pupils Oliver Rawashdeh removed from the gland the fish and found that they could now memories at a high level during the night. Remove the melatonin-producing gland, the researchers of the hormone to alleviate the negative side effects that may show that more Melatonin inhibits the formation of new memories during the night.

With these findings, Roman hopes to be able to hold and the positive effects of melatonin's antioxidant properties. These benefits include combating free radicals damage to slow some forms of neurodegeneration, like Parkinson's and Alzheimer's diseases, and stopping of DNA damage, which has the potential to be a preventative against cancer. And since the positive antioxidant effect is directly and independently of receptor signaling, there is hope that removing the melatonin receptor signaling is against this hormone only the negative effects on cognitive functions.

addition, Roman said that the inhibition of melatonin signaling receptor antagonists may help, with a large number of nocturnal cognitive tasks that help people such as students, for the finals, airplane pilots, ER doctors and the night-shift workers. Roman also believes that a natural role of melatonin can be used to facilitate the storage of memories, during the day, and that further studies are necessary to the ultimate role of melatonin, in memory formation.

"The value of melatonin as a supplement is largely due to its antioxidant properties," said Roman. "The use of melatonin receptor antagonists has no influence on this attribute, but it can alleviate a significant adverse effect on cognitive functions at night."

In other words, a "best of both worlds" scenario could lead to the benefits of melatonin's antioxidant benefits, while improving nighttime memory formation, which is now locked .

Roman's team of UH breakthrough for this study include Gregory M. Cahill, a professor of biology and biochemistry, and two of her students and research assistants, Oliver Rawashdeh and Nancy Hernandez's Borsetti .

----------------------------< Br> article adapted from Medical News today from the original press release. ,

Source: Roman

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Source: Lisa Merkl

University of Houston