TUESDAY, Aug. 1, 2006 (HealthDay News) -- - Like the body clock, which uses cues from the sun to tell you when to sleep, you also have a "food clock" that reminds you when to eat. And scientists now say they're gaining insight into what makes it tick.
In a new study, a team of American and Japanese researchers report that they've discovered genes in mice that play a role in helping the food clock hijack the body clock when necessary.
While it's too early to know for sure, the findings could bring scientists one step closer to adjusting the body's clocks to help obese people lose weight, said study senior author Dr. Masashi Yanagisawa, a professor of molecular genetics at the University of Texas Southwestern Medical Center. "I don't have any concrete idea for a medication right now, but this is the first step," he added.
Scientists have long known about the 24-hour body clock, which adjusts your sleeping cycles to day-and-night cycles. "It is the master clock, and it dominates everything else under normal conditions," Yanagisawa said.
But recently, scientists have also become aware of the molecular food clock. In the new study, the researchers tried to figure out how it works by tinkering with the feeding cycles of mice.
Mice are nocturnal and normally eat at night. But the scientists adjusted their eating patterns by only making food available in a short period during daytime.
As a result, the mice switched their waking patterns after a few weeks, essentially becoming diurnal animals that are active in the daytime. The mice also showed an increase in wakefulness and food-seeking behavior right before food became available.
The researchers euthanized the mice at various times of day and analyzed their brains. They found that certain genes turned on in the mice around their scheduled mealtimes, Yanagisawa said.
Apparently, these genes overpower the ones that suggest the mice should be sleeping during the day. "The food clock is normally a dormant state. It's kind of silent," Yanagisawa said. But in the experiments, "ultimately food is more important than light. The animal suddenly starts to ignore the master clock and the food clock clicks in," he added.
According to Yanagisawa, the new study adds to existing research suggesting that an area of the brain known as the dorsomedial hypothamalic nucleus is the food clock, he said.
The next step is to figure out how "this clock is regulating our appetite and motivation to eat," he said.
In the future, scientists will need to figure out several things about the clock, said Dr. Joseph Bass, a metabolism researcher at Northwestern University. Among the mysteries: how does the food clock center communicate with the rest of the brain? How do disruptions in eating cycles affect it? And how can the "circuits" be adjusted?
Ultimately, such research could help scientists better understand conditions such as obesity and diabetes, which are connected to the body's metabolism, added sleep researcher Dr. Robert Vorona, an assistant professor at Eastern Virginia Medical School.
The findings appear in this week's issue of the Proceedings of the National Academy of Sciences.
More information
The basics of body clocks are explained by the National Institute of Mental Health.
