Featured Research

from universities, journals, and other organizations

Leptin Linked To Obesity And Blood Clots

Date:
April 3, 2002
Source:
University Of Michigan Health System
Summary:
High levels of leptin, a hormone produced by fat cells in the body, could explain why obese people develop dangerous blood clots -– which can cause heart attacks and strokes – more often than people who are not overweight.

ANN ARBOR, Mich. – High levels of leptin, a hormone produced by fat cells in the body, could explain why obese people develop dangerous blood clots -– which can cause heart attacks and strokes – more often than people who are not overweight.

The association between obesity and blood clots is well known; but the cause has remained a mystery. Now, new research with mice conducted by scientists at the University of Michigan Medical School and published in the April 3 issue of the Journal of the American Medical Association, indicates that leptin may be responsible.

“Our results suggest that clot formation begins with some type of interaction between leptin and the leptin receptor on platelets – blood cells which stick together to make clots,” says Daniel T. Eitzman, M.D., a cardiologist at the U-M Cardiovascular Center and an assistant professor of internal medicine in the Medical School.

Knowing how to block this leptin-receptor interaction could help prevent heart attacks and strokes in people who are either obese or overweight, which is half the adult population of the United States.

According to Eitzman, leptin released by fat cells regulates body weight in part by suppressing appetite. When leptin levels in blood go up, the brain signals us to stop eating. But the system breaks down for those who are grossly overweight. Since they have more and larger leptin-producing fat cells than thinner people, their leptin levels increase substantially with every pound of additional weight gain. When leptin reaches very high levels in the blood, Eitzman explains, obese people become resistant to leptin’s signal – making them increasingly vulnerable to leptin-induced blood clotting.

While it certainly plays a major role, Eitzman emphasizes that leptin may not be the only factor involved. “The link between obesity and cardiovascular disease is very complex, and there is much we don’t know about how other blood clotting factors are regulated in obesity,” he says.

Eitzman’s discovery of the relationship between leptin and clotting was a lucky accident. Originally, he had no intention of focusing on leptin at all. He just wanted to examine how obesity affects blood clot formation. So he decided to use the fattest laboratory mice he could find – a strain of mutant mice that just happened to be missing the gene required to produce leptin.

When Eitzman began his experiments, the first results were surprising. Contrary to his expectations, leptin-deficient obese mice took nearly twice as long (an average of 75.2 minutes) to form blood clots as normal mice (42.2 minutes). Eitzman ran his experiment again -- this time using a different strain of obese mice, which were missing the gene for the leptin receptor. These mice also took an abnormally long time to clot (68.6 minutes).

“Finally we tried injecting the mice with leptin, and that’s when clotting times in the leptin-deficient mice dropped to normal [41.8 minutes],” said Eitzman. “That’s when we first knew that leptin was the critical factor. To confirm our results, we transplanted bone marrow from leptin-deficient to normal mice. When the transplanted bone marrow began producing platelets without the leptin receptor, clotting time in the normal mice was prolonged significantly.”

Recent research by other scientists found evidence for leptin’s role in human blood clotting. Results from the West of Scotland Coronary Prevention Study, published in the December 2001 issue of Circulation, showed that high levels of leptin were an independent risk factor for cardiovascular thrombotic events, such as heart attacks and strokes, in 1,160 men enrolled in the prospective study.

“We suspect that the more leptin in blood plasma, the higher the risk of forming blood clots, but we haven’t quantified the relationship yet,” Eitzman says. “We know that losing weight lowers the amount of leptin in your bloodstream, however. So for now diet and exercise remain the best way to prevent blood clots and the strokes and heart attacks they cause.”

Eitzman and his research team also are studying the relationship between leptin and insulin sensitivity to try to discover why diabetics have a higher-than-normal risk of blood clots.

This study was funded by the National Institutes of Health. Other U-M Medical School researchers involved in the study included Peter F. Bodary, Ph.D., the paper’s lead author, who is now at the University of Toledo; Randal J. Westrick, graduate student; Kevin J. Wickenheiser, undergraduate; and Yuechen Shen, M.D., research associate.


Story Source:

The above story is based on materials provided by University Of Michigan Health System. Note: Materials may be edited for content and length.


Cite This Page:

University Of Michigan Health System. "Leptin Linked To Obesity And Blood Clots." ScienceDaily. ScienceDaily, 3 April 2002. <www.sciencedaily.com/releases/2002/04/020403025940.htm>.
University Of Michigan Health System. (2002, April 3). Leptin Linked To Obesity And Blood Clots. ScienceDaily. Retrieved August 20, 2014 from www.sciencedaily.com/releases/2002/04/020403025940.htm
University Of Michigan Health System. "Leptin Linked To Obesity And Blood Clots." ScienceDaily. www.sciencedaily.com/releases/2002/04/020403025940.htm (accessed August 20, 2014).

Share This




More Health & Medicine News

Wednesday, August 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Possible Ebola Patient in Isolation at California Hospital

Possible Ebola Patient in Isolation at California Hospital

Reuters - US Online Video (Aug. 20, 2014) — A patient who may have been exposed to the Ebola virus is in isolation at the Kaiser Permanente South Sacramento Medical Center. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Raw: World's Oldest Man Lives in Japan

Raw: World's Oldest Man Lives in Japan

AP (Aug. 20, 2014) — A 111-year-old Japanese was certified as the world's oldest man by Guinness World Records on Wednesday. Sakari Momoi, a native of Fukushima in northern Japan, was given a certificate at a hospital in Tokyo. (Aug. 20) Video provided by AP
Powered by NewsLook.com
Do More Wedding Guests Make A Happier Marriage?

Do More Wedding Guests Make A Happier Marriage?

Newsy (Aug. 20, 2014) — A new study found couples who had at least 150 guests at their weddings were more likely to report being happy in their marriages. Video provided by Newsy
Powered by NewsLook.com
Ebola-Hit Sierra Leone's Freetown a City on Edge

Ebola-Hit Sierra Leone's Freetown a City on Edge

AFP (Aug. 19, 2014) — Residents of Sierra Leone's capital voice their fears as the Ebola virus sweeps through west Africa. Duration: 00:56 Video provided by AFP
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