A new study in mice finds that at high doses, VIP, a molecule that normally synchronizes biological clock cells in the brain, knocks them out of synch, allowing them to reset quickly to a new light-dark cycle.
The researchers - from Washington University in St. Louis, MO, and the University of California, Santa Barbara - suggest the finding may help develop treatments for sleep problems brought on by jet lag and shift work.
In a recent issue of the Proceedings of the National Academy of Sciences (PNAS), they explain how desynchronized neurons took only half as long as undisturbed brain cells to entrain to a new light-dark cycle.
In mammals, the master biological clock is a cluster of 20,000 neurons that form the suprachiasmatic nucleus (SCN) - a knot of brain tissue about the size of a grain of rice, which in humans sits on the brain's midline.
Marking time
Each brain cell in the SCN keeps time, but being individual cells, they have different rhythms.
However, they seem to tell each other about their individual timekeeping using a molecule called VIP (vasoactive intestinal polypeptide), which helps them stay synchronized, as Erik Herzog, a professor of biology in Arts & Sciences at Washington University, explains:
"They're like a society where each cell has its own opinion on what time of day it is. They need to agree on the time of day in order to coordinate daily rhythms in alertness and metabolism."
He says if you get rid of VIP or the receptor for VIP, the cells fall out of step with each other.
But as the researchers were trying to discover exactly how VIP works to synchronize cells, they found to their surprise that with too much VIP, the cells become desynchronized. And the more VIP that was released, the more desynchronized they became.
Prof. Herzog explains:
"It's almost as if at higher doses the cells become blind to the information from their neighbors."
No comments:
Post a Comment