Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Insulin pulses keep the liver lean

20.07.2005


Insulin, a hormone long recognized as a generator of fat, also keeps fat in the liver under control, according to a new study in the July issue of Cell Metabolism. The newly discovered role for insulin may explain how an organ frequently flooded with the fat-building hormone normally stays trim and also suggests new dietary strategies and treatments to avoid fatty liver, a growing healthcare epidemic, said the researchers.



Insulin produced by the pancreas allows cells to take up glucose from the bloodstream and burn it for energy. In the liver, insulin promotes the synthesis and storage of lipids and carbohydrates and blocks their breakdown and release into the bloodstream. A failure to make or respond to insulin in people with diabetes causes blood sugar levels to rise.

The current study uncovered a new mechanism whereby acute insulin pulses limit fat synthesis in the liver. This protective mechanism fails in obese mice and mice with persistently high levels of insulin, the researchers also found.


The findings suggest that periods of fasting between meals play a critical role in maintaining a lean and healthy liver by allowing insulin levels to rise and fall, said study lead author Sonia Najjar of the Medical University of Ohio.

Furthermore, she said, the results emphasize the central role of the liver in metabolic control. A liver overwhelmed with insulin--as can occur in those who overeat--may become resistant to the hormone, leading to greater fat production and visceral weight gain. Resulting hikes in blood sugar and fat can also spell diabetes and heart disease, Najjar added.

"When we eat, the pancreas produces insulin, which stimulates the absorption of sugar and fat by the liver," Najjar said. "But in today’s Western society, large portions and frequent munching may lead insulin levels to remain high all the time. In that case, the liver no longer perceives pulses of the hormone and becomes resistant."

The researchers found that insulin pulses acutely reduce the activity of fat-building fatty acid synthase (FAS) in the liver by activating a second liver molecule, called CEACAM1. In mice lacking CEACAM1, insulin lost its ability to limit liver FAS activity. Obese mice and those with too much insulin also failed to exhibit a reduction in liver FAS activity following insulin delivery, suggesting that insulin’s effects depend on prior levels of the hormone, the researchers reported.

"The current data demonstrate that CEACAM1 is at the intersection of the pathways regulating insulin and fat metabolism in liver," Najjar said.

"Although mutations in CEACAM1 have not been found in patients with diabetes or insulin resistance, it is tempting to speculate that CEACAM1-dependent inhibition of fatty acid synthesis might be compromised as a consequence or even a cause of the insulin-resistant state," wrote Alan Saltiel of the University of Michigan in an accompanying preview. In this case, he added, finding ways to mimic the effects of CEACAM1 might help to alleviate chronically elevated blood and liver lipids in patients with diabetes.

Heidi Hardman | EurekAlert!
Further information:
http://www.cell.com

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>