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 New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>