Sleepless aged rats show biological cloc...( One of the problems of the aged is gett...)

One of the problems of the aged is getting a good nights sleep. Often, the elderly sleep fitfully through the night only to be overcome by drowsiness during the day and nodding off then. A general feeling of tiredness and irritability goes hand-in-hand with this condition. Now a biologist at Washington University in St. Louis and colleagues from France and the University of Virginia have found this problem may be traced to a faulty biological clock at least in aged rats.

Erik Herzog, Ph.D., assistant professor of biology at Washington University, examined cells involved in the generation of circadian rhythms the 24-hour cycles in things like alertness and hormone levels. In collaboration with Fabienne Aujard, D.V.M., Ph.D., of Frances Centre National de la Recherche Scientifique, and Gene Block, Ph.D., professor of biology at the University of Virginia, Herzog found that the electrical activity of the clock cells in aged rats was not regular compared with that of young and middle-aged rats.

"In the case of the aged rats, many of them showed fragmented behavioral rhythms," Herzog explained. "They were still rhythmic, but showed bouts of activity when the rats normally would have rested and inactivity when the young animals were active. "So, the rats, like elderly humans, took naps when they would have normally been active. Remarkably, the cells in their biological clock reflected this behavior."

The research is supported by the National Institutes of Health and will be published in the forthcoming issue of Neuroscience. Herzog cannot surmise exactly what role aging is playing in this irregularity, but he doesnt think its a result of the circadian rhythm network breaking down.

"The deterioration of rhythmicity would appear to be a single cell property," he said. "The individual pacemaker cells appear to be losing their ability to mark time. We could argue that this is evidence of aging acting at the level of sin
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Contact: Tony Fitzpatrick
tony_fitzpatrick@aismail.wustl.edu
314-935-5272
Washington University in St. Louis
13-Aug-2001

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