Caption: Lipids (red) inside mouse intestinal cells with and without NFIL3. Credit: Lora V. Hooper, University of Texas Southwestern Medical Center, Dallas
The American epidemic of obesity is a major public health concern, and keeping off the extra pounds is a concern for many of us. Yet it can also be a real challenge for people who may eat normally but get their days and nights mixed up, including night-shift workers and those who regularly travel overseas. Why is that?
The most obvious reason is the odd hours throw a person’s 24-hour biological clock—and metabolism—out of sync. But an NIH-funded team of researchers has new evidence in mice to suggest the answer could go deeper to include the trillions of microbes that live in our guts—and, more specifically, the way they “talk” to intestinal cells. Their studies suggest that what gut microbes “say” influences the activity of a key clock-driven protein called NFIL3, which can set intestinal cells up to absorb and store more fat from the diet while operating at hours that might run counter to our fixed biological clocks.
School’s starting soon, and a lot of kids (and some adults) who were sleeping late this summer are struggling to reset their sleep cycles. All summer, those biological clocks have been getting pushed back. Artificial light allows us to work and play into the wee hours, interfering with the natural light-dark cycle that, over most of human history, began at sunrise and ended just after sunset.
But there’s a price to be paid for this modern shifting of biological clocks: research shows that long term indulgence in these late sleep schedules leads to unwanted weight gain and obesity, mood problems, substance abuse, and, of course, morning sleepiness. Light and sleep are critical to good health—and that’s one reason NIH funded a team at the University of Colorado Boulder to investigate the impact of natural light on our modern sleep patterns . Continue reading →
The neurons in the SCN are coupled oscillators, like these metronomes on a moveable table that has enough wiggle that each metronome’s motion affects the others’. Like the metronomes the neurons keep time individually and, because the VIP network couples them, they synchronize their beats.
Video by the Ikeguchi Laboratory, in the graduate school of science and engineering at Saitama University in Japan.
Did you know you have a biological clock in your brain that drives your sleep patterns and metabolism?
The clock is mostly in a brain region called the suprachiasmatic nucleus—a collection of about 20,000 brain cells, or neurons. Each one of these neurons can keep time, just like a metronome sitting on a piano. Together, these 20,000 biological clocks are kept perfectly synchronized, and they are accurate to about a few minutes within a 1440-minute day. A brain signaling chemical called VIP (vasoactive intestinal polypeptide) plays an important role in keeping all of the neurons ticking in unrelenting lock step. But VIP doesn’t work alone. Continue reading →