Featured Research

from universities, journals, and other organizations

Most-used diabetes drug works in different way than previously thought

Date:
January 6, 2013
Source:
University of Pennsylvania School of Medicine
Summary:
Researchers found that the diabetes drug metformin works in a different way than previously understood. Their research in mice found that metformin suppresses the liver hormone glucagon's ability to generate an important signaling molecule, pointing to new drug targets.

Proposed model: Metformin enters the cell and acts on the mitochondria, causing increased AMP. Elevated cellular AMP levels inhibit membrane bound adenylyl cyclase, causing a reduction in cellular cAMP levels and decreased PKA activation and target phosphorylation.
Credit: Morris Birnbaum, M.D., Ph.D., Perelman School of Medicine, University of Pennsylvania; Nature

A team, led by senior author Morris J. Birnbaum, MD, PhD, the Willard and Rhoda Ware Professor of Medicine, with the Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, found that the diabetes drug metformin works in a different way than previously understood. Their research in mice found that metformin suppresses the liver hormone glucagon's ability to generate an important signaling molecule, pointing to new drug targets. The findings were published online this week in Nature.

Related Articles


For fifty years, one of the few classes of therapeutics effective in reducing the overactive glucose production associated with diabetes has been the biguanides, which includes metformin, the most frequently prescribed drug for type 2 diabetes. The inability of insulin to keep liver glucose output in check is a major factor in the high blood sugar of type 2 diabetes and other diseases of insulin resistance.

"Overall, metformin lowers blood glucose by decreasing liver production of glucose," says Birnbaum. "But we didn't really know how the drug accomplished that."

Imperfectly Understood

Despite metformin's success, its mechanism of action remained imperfectly understood. About a decade ago, researchers suggested that metformin reduces glucose synthesis by activating the enzyme AMPK. But this understanding was challenged by genetic experiments in 2010 by collaborators on the present Nature study. Coauthors Marc Foretz and Benoit Viollet from Inserm, CNRS, and Universitι Paris Descartes, Paris, found that the livers of mice without AMPK still responded to metformin, indicating that blood glucose levels were being controlled outside of the AMPK pathway.

Taking another look at how glucose is regulated normally, the team knew that when there is no food intake and glucose decreases, glucagon is secreted from the pancreas to signal the liver to produce glucose. They then asked if metformin works by stopping the glucagon cascade.

The Nature study describes a novel mechanism by which metformin antagonizes the action of glucagon, thus reducing fasting glucose levels. The team showed that metformin leads to the accumulation of AMP in mice, which inhibits an enzyme called adenylate cyclase, thereby reducing levels of cyclic AMP and protein kinase activity, eventually blocking glucagon-dependent glucose output from liver cells.

From this new understanding of metformin's action, Birnbaum and colleagues surmise that adenylate cyclase could be a new drug target by mimicking the way in which it is inhibited by metformin. This strategy would bypass metformin's affect on a cell's mitochondria to make energy, and possibility avoid the adverse side effects experienced by many people who take metformin, perhaps even working for those patients resistant to metformin.


Story Source:

The above story is based on materials provided by University of Pennsylvania School of Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. Russell A. Miller, Qingwei Chu, Jianxin Xie, Marc Foretz, Benoit Viollet, Morris J. Birnbaum. Biguanides suppress hepatic glucagon signalling by decreasing production of cyclic AMP. Nature, 2013; DOI: 10.1038/nature11808

Cite This Page:

University of Pennsylvania School of Medicine. "Most-used diabetes drug works in different way than previously thought." ScienceDaily. ScienceDaily, 6 January 2013. <www.sciencedaily.com/releases/2013/01/130106145741.htm>.
University of Pennsylvania School of Medicine. (2013, January 6). Most-used diabetes drug works in different way than previously thought. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2013/01/130106145741.htm
University of Pennsylvania School of Medicine. "Most-used diabetes drug works in different way than previously thought." ScienceDaily. www.sciencedaily.com/releases/2013/01/130106145741.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. Video provided by Newsy
Powered by NewsLook.com
Winter Can Cause Depression — Here's How To Combat It

Winter Can Cause Depression — Here's How To Combat It

Newsy (Nov. 23, 2014) — Millions of American suffer from seasonal depression every year. It can lead to adverse health effects, but there are ways to ease symptoms. Video provided by Newsy
Powered by NewsLook.com
Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

Ebola-Hit Sierra Leone's Late Cocoa Leaves Bitter Taste

AFP (Nov. 23, 2014) — The arable district of Kenema in Sierra Leone -- at the centre of the Ebola outbreak in May -- has been under quarantine for three months as the cocoa harvest comes in. Duration: 01:32 Video provided by AFP
Powered by NewsLook.com
Don't Fall For Flu Shot Myths

Don't Fall For Flu Shot Myths

Newsy (Nov. 23, 2014) — Misconceptions abound when it comes to your annual flu shot. Medical experts say most people older than 6 months should get the shot. 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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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