Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why obesity surgery helps in diabetes

03.09.2008
To manage obesity, various different surgical procedures can be performed on the stomach, including so-called bypass surgery in which, as well as reducing the size of the stomach, a bypass is created to send food directly into the distal gut (which, before the operation, is far from the stomach).

In obese patients who also suffer from diabetes, spectacular improvement in the diabetes is routinely observed following this type of operation although the mechanism underlying this phenomenon was not understood.

Now, experiments conducted in mice by scientists from Université Claude Bernard – Lyon 1, Inserm, CNRS, INRA and the Hôpital Bichat in Paris, have elucidated the mechanism in question. The bypass stimulates glucose synthesis in the gut, an effect that is sustained between meals. Detection of this glucose induces the sending of a signal to the brain which leads to enhanced responsiveness to insulin. These findings—which are reported in the September issue of the journal Cell Metabolism—could point to novel therapeutic approaches in both obesity and diabetes.

In obese patients, the main objective of gastric surgery is to reduce the size of the stomach and this is most commonly achieved by implanting a gastric ring. When the patient also suffers from diabetes, the latter condition tends to improve once he or she has lost some weight. Bypass surgery however has a specific effect in that dramatic improvement is obtained almost immediately—as of discharge of the patient from hospital—a phenomenon which has been hitherto poorly understood. In this form of surgery, as well as reducing the size of the stomach, a bypass is created to send food directly into the distal intestine (which, before the operation, is far from the stomach). The proximal intestine (which is physiologically located immediately after the stomach) is left in place but it no longer receives any food.

Fabrizio Andréelli and his team (Inserm Unit 695, Hôpital Bichat, Paris) have developed models of "ring" and "bypass" surgery in mice in order to elucidate the specific effects of the two techniques.

It was already known that, in the gut (specifically in the wall of the portal vein*), there is a nerve-based system capable of detecting glucose and sending this information to the brain. In 2005, Gilles Mithieux (Inserm Unit 855, Université Lyon 1, INRA–USC 2028) showed that when de novo glucose synthesis is triggered in the intestine (in a process called neoglucogenesis), this signalling system is activated. The sending of the message results in attenuation of feelings of hunger and also has a beneficial effect on blood glucose regulation.

* the portal vein collects blood coming from the gut
Now, the teams of Fabrizio Andréelli and Gilles Mithieux, in collaboration with those of Christophe Magnan (CNRS UMR 7059, Paris 7) and Bernard Thorens (Lausanne), have tested the hypothesis that intestinal neoglucogenesis is involved in the observed, specific effects of gastric bypass surgery. They fed mice a diet rich in lipids and carbohydrates (sugar) to mimic metabolic conditions in diabetic obesity.

The scientists observed strong expression of genes involved in glucose synthesis throughout the guts of the "bypass" mice but not "ring" mice. They also observed that, between meals, glucose was still being released into the portal vein after the ingested food had been absorbed. Enough glucose was being released to trigger the portal vein signalling system, thereby leading to a reduction in the amount of food eaten and dramatic improvement in the ability of insulin to bring the blood glucose concentration down.

These findings shed light on why gastric bypass surgery induces such rapid improvement in diabetes, a phenomenon which was hitherto unexplained.

According to the authors, "These results could point to new therapeutic strategies—surgery or drugs—relevant not only to obesity but also to diabetes".

Séverine Ciancia | alfa
Further information:
http://www.inserm.fr
http://www.cellmetabolism.org/

More articles from Health and Medicine:

nachricht Unique brain 'fingerprint' can predict drug effectiveness
11.07.2018 | McGill University

nachricht Direct conversion of non-neuronal cells into nerve cells
03.07.2018 | Universitätsmedizin der Johannes Gutenberg-Universität Mainz

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>