Biological Organs Have their Own Circadian Clocks

Mo HongYi

It is known that everybody has a Circadian rhythm. Interestingly, scientists have discovered that the organs in our bodies are just like numerous independent lives with their own internal clocks.

Scientists believed that the circadian rhythm of a body was strictly controlled by the master clock located in the brain, but they now have discovered that this is not true. In an article published in the May issue of Nature (Vol. 417, 78 - 83 (2002)), researchers from Harvard Medical School and some other research institutes reported an interesting discovery. By studying the tissues from the hearts and livers of mice, they discovered that the physiological activities of a body were controlled by the local circadian clocks of the organs in the body. The chiming of each organ clock triggers different waves of gene activities, which can be adjusted over time to accommodate new schedules and life activities. The different organ clocks appear to be strikingly idiosyncratic in appearance. For example, the clock located in the liver and the one in the heart use very different sets of genes to perform functions that are basically the same. In the article, Weitz explained, "Different tissues have to be cycling for different reasons. This allows organs to reset their activities according to their own priorities, which makes a lot of sense."

The discovery shows that the organs have their own relatively independent metabolic activities. Ancient Chinese science actually regards these organs as independent lives. For example, the Tao school maintains that our human body is a universe with various kinds of lives in it. Traditional Chinese medicine also treats each organ as an independent system and each different organ with different attributes. They have their own independent life activities, while interacting with each other. For example, in traditional Chinese medicine, there is the theory of five elements: Kidney belongs to water, Liver belongs to wood, Lung belongs to metal, Spleen belongs to earth, etc.. Different organs interact with each other via the principle of mutual generation and mutual inhibition among the five elements. Moreover, ancient Chinese science believes that everything in the world has its own spirit; therefore one would pay attention to the time and season for picking the tea leaves, etc. In addition, there are strict requirements for the virtue of the persons who pick the herbs and teas. In a prescription of Traditional Chinese medicine, different components play different roles in the formula, such as the "emperor," the "minister," the "assistant," and the "envoy." The belief that all things have their own spirits is consistent with scientific experiments.

1. Nature 417, 78 - 83 (2002); doi:10.1038/nature744
2. http://www.sciencedaily.com/releases/2002/04/020422072758.htm
3. Harvard Medical School (http://www.hms.harvard.edu/)

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