Featured Research

from universities, journals, and other organizations

Obesity may shut down circadian clock in the cardiovascular system

Date:
April 13, 2011
Source:
American Physiological Society
Summary:
Researchers have found that a key gene clock of the cardiovascular system does not work properly when obesity is present. The findings are believed to be the first of their kind.

Obese individuals typically suffer more medical problems than their leaner counterparts. They are more likely to be diagnosed with insulin resistance, diabetes, increased stress hormones, hypothyroidism, and sleep apnea. Researchers at the Georgia Health Sciences University in Augusta have also found the potential for something else, using an animal model. They have found that a master clock gene -- which regulates the cardiovascular system -- does not fluctuate regularly as it does in non-obese animals. This means that a key gene clock of the cardiovascular system does not work properly when obesity is present. The findings are believed to be the first of their kind.

The study was conducted by Shuiqing Qiu, Eric Belin de Chantemele, James Mintz, David J. Fulton, R. Daniel Rudic and David W. Stepp. Members of the team will present their findings, entitled, "Impact of obesity on the vascular circadian clock," at the Experimental Biology 2011 meeting (EB 2011), being held April 9-13, 2011 at the Walter E. Washington Convention Center, Washington, DC.

Circadian Biology and Obesity

Humans and animals are essentially programmed to physiologically respond to a day/night cycles based on the 24-hour rotation of the planet. The body has been trained through evolution to respond to day cues by eating and perusing activities and to rest and sleep cues during darkness. Indeed, there is a molecular basis that precisely controls rhythms, a group of genes dubbed the circadian clock, including one molecule also aptly named 'Clock'.

In obese individuals, the natural circadian rhythms are believed to be disrupted. Obese individuals frequently eat at irregular times, and especially late at night. In addition, they often suffer from sleep apnea, which disturbs their sleep rhythm thus causing them to miss a good night's sleep. Shift workers tend to be obese because their physiological requirements are backwards (breakfast may start at 10:00 p.m.) and swing shift workers (who work a week on the day shift followed by a week on the night shift) are predisposed to obesity because their physiological cues "swing" back and forth thus interrupting the natural circadian rhythms.

The Study

With obesity known to affect at least the eat/sleep cycles, the researchers set out to determine whether obesity might also affect the molecular components of the clock that governs the vascular system, the system of the heart and blood vessels that are responsible for moving blood throughout the body. They conducted their research in two phases.

Methodology/Findings: I

In phase I, they examined the circadian variation in the cardiovascular chamber of three groups of mice (lean, obese and diabetic) at three time intervals: early morning, mid-day and evening, and measured the gene expression in the cardiovascular genes during these times.

In the lean animals they found evidence of a cardiovascular rhythm. Among the evidence was the presence of endothelial nitric oxide synthase (eNOS), an enzyme helps coordinate blood flow, thus tends to be elevated at the end of the day and lower in the morning.

By contrast, they found this rhythm was lost in obese animals. For example, eNOS had either shifted its pattern, peaked at the wrong time, or was flat overall. The obese animals had thus lost their ability to control circadian variation of eNOS.

Methodology/Findings: II

In phase II, the team used the data to examine whether the lack of rhythmic response could translate into a cardiovascular defect. They did so by examining a series of specific molecules from the cardiovascular clock genes and by measuring the acceleration of the genes in the blood vessels.

In the lean animals they found that a key regulator of circadian rhythm, a gene called Clock, was high at 7:00 a.m. and low at 7:00 p.m. In the obese animals the expression of the gene remained flat throughout the 24-hour cycle.

Conclusions and Next Steps

David Stepp, Ph.D., a senior researcher on the team, summed up the findings by saying, "Based on the results of this study we now know that obesity impairs the clock machinery of the vasculature system and that correlates with a variation in expression of cardiovascular genes and their loss of the circadian rhythm." Having identified that the Clock gene does not work in the presence of obesity, he says the team has new studies underway to help explain why.


Story Source:

The above story is based on materials provided by American Physiological Society. Note: Materials may be edited for content and length.


Cite This Page:

American Physiological Society. "Obesity may shut down circadian clock in the cardiovascular system." ScienceDaily. ScienceDaily, 13 April 2011. <www.sciencedaily.com/releases/2011/04/110411131339.htm>.
American Physiological Society. (2011, April 13). Obesity may shut down circadian clock in the cardiovascular system. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2011/04/110411131339.htm
American Physiological Society. "Obesity may shut down circadian clock in the cardiovascular system." ScienceDaily. www.sciencedaily.com/releases/2011/04/110411131339.htm (accessed July 23, 2014).

Share This




More Health & Medicine News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Idaho Boy Helps Brother With Disabilities Complete Triathlon

Newsy (July 23, 2014) An 8-year-old boy helped his younger brother, who has a rare genetic condition that's confined him to a wheelchair, finish a triathlon. Video provided by Newsy
Powered by NewsLook.com
Thousands Who Can't Afford Medical Care Flock to Free US Clinic

Thousands Who Can't Afford Medical Care Flock to Free US Clinic

AFP (July 23, 2014) America may be the world’s richest country, but in terms of healthcare, the World Health Organisation ranks it 37th. Thousands turned out for a free clinic run by "Remote Area Medical" with a visit from the Governor of Virginia. Duration: 2:40 Video provided by AFP
Powered by NewsLook.com
Stone Fruit Listeria Scare Causes Sweeping Recall

Stone Fruit Listeria Scare Causes Sweeping Recall

Newsy (July 22, 2014) The Wawona Packing Company has issued a voluntary recall on the stone fruit it distributes due to a possible Listeria outbreak. Video provided by Newsy
Powered by NewsLook.com
Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Huge Schizophrenia Study Finds Dozens Of New Genetic Causes

Newsy (July 22, 2014) The 83 new genetic markers could open dozens of new avenues for schizophrenia treatment research. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins