Navigation Links
Insulin pulses keep the liver lean

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 resea rchers 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.

Najjar et al.: "Insulin acutely decreases hepatic fatty acid synthase activity." Publishing in Cell Metabolism, Vol. 2, July 2005, pages 43-53. DOI 10.1016/j.cmet.2005.06.001. www.cellmetabolism.org


'"/>

Source:Cell Press


Related biology news :

1. NIH Researchers Discover How Insulin Allows Entry of Glucose Into Cells
2. Insulin receptor stops progression of Alzheimers disease
3. Field of beams - Novel system uses polarized light pulses to reveal crop health
4. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
5. New methods of gene delivery using lasers
6. UNC launches study of liver injury caused by drugs
7. Gene therapy cures inherited liver disease in rats
8. Mouse with designer liver has enhanced glucose tolerance, insulin response
9. Excess liver gene protects against high-fat diet
10. Recombinant DNA technology may enable oral, rather than injectable, delivery of protein drugs
11. Self-assembled DNA buckyballs for drug delivery
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:4/5/2017)... , April 5, 2017 Today HYPR ... that the server component of the HYPR platform is ... providing the end-to-end security architecture that empowers biometric authentication ... HYPR has already secured over 15 million users across ... manufacturers of connected home product suites and physical access ...
(Date:4/3/2017)... 2017  Data captured by IsoCode, IsoPlexis ... a statistically significant association between the potency ... and objective response of cancer patients post-treatment. ... whether cancer patients will respond to CAR-T ... as to improve both pre-infusion potency testing and ...
(Date:3/30/2017)... -- Trends, opportunities and forecast in this market to ... AFIS, iris recognition, facial recognition, hand geometry, vein recognition, ... industry (government and law enforcement, commercial and retail, health ... and by region ( North America , ... , and the Rest of the World) ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... October 12, 2017 , ... ... the first-ever genomics analysis platform specifically designed for life science researchers to ... of pioneering researcher Rosalind Franklin, who made a major contribution to the ...
(Date:10/11/2017)... ... 11, 2017 , ... ComplianceOnline’s Medical Device Summit is back for its 4th ... in San Francisco, CA. The Summit brings together current and former FDA office bearers, ... and government officials from around the world to address key issues in device compliance, ...
(Date:10/11/2017)... Tbilisi, Georgia (PRWEB) , ... October 11, 2017 , ... ... disaster, taking the lives of over 5.5 million people each year. Especially those living ... the greenovative startup Treepex - based in one of the most pollution-affected countries globally ...
(Date:10/10/2017)... Los Angeles, CA (PRWEB) , ... ... ... Pharmaceuticals, Inc., a development-stage cancer-focused pharmaceutical company advancing targeted antibody-drug conjugate (ADC) ... all uses of targeted HPLN (Hybrid Polymerized Liposomal Nanoparticle), a technology developed ...
Breaking Biology Technology: