Navigation Links
Discovery clarifies role of peptide in biological clock

A biologist at Washington University in St. Louis is giving the VIP treatment to laboratory mice in hopes of unraveling more clues about our biological clock.

VIP is not "very important person," but vasoactive intestinal polypeptide (VIP), a neuropeptide originally found in the gut, that is also made by a specialized group of neurons in the brain.

Erik Herzog, Ph.D., Washington University assistant professor of Biology in Arts & Sciences, has discovered that VIP is needed by the brain's biological clock to coordinate daily rhythms in behavior and physiology. Neurons in the biological clock, an area called the suprachiasmatic nucleus (SCN), keep 24-hour time and are normally synchronized as a well-oiled marching band coming onto the field at half time. Herzog and graduate student, Sara Aton, found that mice lacking the gene that makes VIP or lacking the receptor molecule for VIP suffer from internal de-synchrony. When they recorded the electrical activity of SCN neurons from these mice, they found that many had lost their beat while others were cycling but unable to synch to each other.

But when Herzog and Aton added VIP to the mice cells, the synchronicity was restored, showing that VIP couples pacemaker cells and drives rhythms in slave cells.

"VIP between SCN neurons is like a rubber band between the pendulums of two grandfather clocks, helping to synchronize their timing. Some researchers had proposed that knocking out VIP or the receptor for it stopped the clock," Herzog said. "We've found that the biological clock is still running, but its internal synchrony is uncoordinated. This causes irregular patterns of sleep and wake, for example."

The study was published on-line in Nature Neuroscience on March 6, 2005. Herzog's work is funded by the National Institutes of Health.

"In a light-dark schedule, these mice looked normal, but as soon as you leave off the lights, they reveal their internal de-synchrony," he sai d. "The mice showed multiple rhythms, getting up both earlier and earlier and later and later on subsequent days so that their daily activity patterns were splitting apart."

Herzog and Aton recorded neuron activity from the SCN using a multielectrode array with 60 electrodes upon which they place SCN cells, a "clock in a dish." This enabled them to record data from many cells for many days.

"We found that the VIP mutants, indeed, can generate circadian rhythms, but the neurons can't synchronize to each other," Herzog said. "We showed that we could restore rhythms to the arrhythmic neurons and synchrony to the SCN by providing VIP once a day."

The SCN is a part of the hypothalamus that can be found on the bottom of the brain just above the roof of your mouth where your optic nerves cross. There are roughly 10,000 neurons in this nucleus on either side of your brain. The timekeeping mechanism in these cells depends on daily cycles in gene activity.

Herzog found in his latest study that the percentage of rhythmic cells in the mutant SCN was very low, and he believes these rhythmic neurons are specialized circadian pacemakers.

"We suspect that at least some of the pace making cells in the SCN are VIP cells, and one of the things we'll try to do next is confirm this. We will also try to understand better how VIP synchronizes pacemakers," he said.

It is surprising that the process is regulated by a peptide, usually a slow signaling agent, rather than a neurotransmitter, associated with fast events, Herzog said.

"We're trying to understand the mechanics of how the system synchronizes and the secondary messenger systems as well," Herzog said. "We're getting closer to the heart and soul of circadian rhythmicity by uncoupling the (biological) clock."


Source:Washington University in St. Louis

Related biology news :

1. Fundamental Finding Yields Insight into Stem Cells, Cancer; Opens Door to Drug Discovery
2. Discovery of key proteins shape could lead to improved bacterial pneumonia vaccine
3. UCSD Discovery Shows How Embryonic Stem Cells Perform Quality Control Inspections
4. Discovery Could Lead To Novel Approaches In HIV Treatment
5. Discovery Promises Simpler Therapy for Sickle Cell Disease
6. Discovery may lead to better Candidiasis drug
7. Protein Discovery Could Unlock The Secret To Better TB Treatment
8. Eliminate Data Analysis Bottlenecks in Drug Discovery
9. Discovery of New Dopamine Action May Yield Alternative Psychiatric Drugs
10. Discovery could be key to bioterrorism defense
11. Discovery of an American salamander where it shouldnt be: Korea
Post Your Comments:

(Date:11/9/2015)... , Nov. 9, 2015  Synaptics Inc. (NASDAQ: ... today announced broader entry into the automotive market with ... match the pace of consumer electronics human interface innovation. ... are ideal for the automotive industry and will be ... Europe , Japan ...
(Date:10/29/2015)... , Oct. 29, 2015  The J. Craig Venter ... titled, "DNA Synthesis and Biosecurity: Lessons Learned and Options ... of Health and Human Services guidance for synthetic biology ... --> --> ... has the potential to pose unique biosecurity threats. It ...
(Date:10/29/2015)... , October 29, 2015 ... authentication company focused on the growing mobile commerce ... announces that StackCommerce, a leading marketplace to discover ... the Wocket® smart wallet on StackSocial for this ... ("NXT-ID" or the "Company"), a biometric authentication company ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... - ProMetic Life Sciences Inc. (TSX: PLI) (OTCQX: PFSCF) ("ProMetic" ... , President and Chief Executive Officer of ProMetic, will be ... th Annual Healthcare Conference to be held at the ... st , at 8.50am (ET) and ProMetic,s management team ... presentation will be available live via a webcast accessible at ...
(Date:11/24/2015)... Nev. , Nov. 24, 2015  PDL BioPharma, Inc. ... P. McLaughlin , the company,s president and chief executive officer, ... Healthcare Conference next week in New York City ... occur on Tuesday, December 1, 2015 at 9:30 a.m. EST. ... Please connect to the website at least 15 minutes prior ...
(Date:11/24/2015)... Nov. 24, 2015 According to two new studies, ... This is something that many doctors, scientists, and public health ... remains: with fewer PSA tests being done, will there be ... Dr. David Samadi, "Despite the efforts made in ... the second leading cancer cause of death in men, killing ...
(Date:11/23/2015)... 2015 China Cord Blood Corporation (NYSE: ... of cord blood collection, laboratory testing, hematopoietic stem cell ... preliminary unaudited financial results for the second quarter and ... 2015. --> --> ... for the second quarter of fiscal 2016 increased by ...
Breaking Biology Technology: