Melatonin is best known as a dietary supplement for helping people get to sleep, but the naturally occurring hormone also plays a part in regulating the biological clocks of mammals.
Thomas Champney, associate professor in the Department of Human Anatomy of the College of Medicine at The Texas A&M University System Health Science Center, has studied the effects of melatonin in rodents for over 20 years. Champney is also an affiliate faculty member of Texas A&M University’s new Center for Biological Clocks Research.
“Melatonin is produced by the pineal gland, a small organ located in the brain, and helps regulate the daily rhythms of mammalian physiological processes,” Champney said. “Amounts of melatonin are low during the day and high at night, helping to explain its use as a sleep aid. My research, however, rather than focusing on daily rhythms, centers on the seasonal and yearly aspects of rodent (particularly hamster) physiological cycles.
“For example, melatonin production influences the immune system, causing it to cycle up and down on a yearly basis,” he observed. “It also plays an important part in the rodent reproductive cycle. Since most animals want to produce their young in the spring and the duration of melatonin is greater in the longer, darker winter months, the hormone helps the animal sense the optimum times for reproduction to produce spring-time litters.
“Essentially, long duration melatonin levels tell the hamsters it’s winter, thus it?s not the right time for sex for an animal with such a short gestational period.”
Champney studies pineal gland function in the presence and absence of melatonin.
“I’ve found, for example, that melatonin given in the morning has no effect on the hamsters, but if it is given to them in the afternoon, it will impact their physiological processes,” Champney said. “Thus, the animals appear to exhibit a differential sensitivity to melatonin at given times of the day.”
Champney has also been observing the effect of melatonin on cultured cells from the adrenal glands of rats. These cells secrete dopamine, and melatonin seems to influence that process. Other studies he’s conducted indicate that melatonin given in conjunction with anticonvulsants can moderate seizures in
rodents.
Although Champney’s research doesn’t extend to humans, he said that the biggest benefits of the hormone in people involve treatment of jet lag and initiating sleep.
“If one begins taking melatonin, before a trip, at the time when he would be getting to sleep at his destination, jet lag seems to be lessened,” Champney said. “As to the other implications of my studies, there does not appear to be any connection between melatonin and human reproduction.”
Champney’s work will be part of the program of the newly approved Center for Biological Clocks Research, administered through the Texas A&M Department of Biology but involving researchers from other university departments and the A&M System Health Science Center. The Center will build upon current institutional interdisciplinary research strengths in the field of biological rhythms and the ‘clocks’ that control them.
The Texas A&M University System Health Science Center provides the state with health education, outreach and research. Its five components located in communities throughout Texas are Baylor College of Dentistry, the College of Medicine, the Graduate School of Biomedical Sciences, the Institute of Biosciences and Technology and the School of Rural Public Health.

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