The observation is as old as gastrointestinal surgery. Back in those days when patients suffering from a stomach ulcer had to undergo surgery a lot more often than today, one of the most popular methods was surgical vagectomy, i. e. the clipping of the Nervus vagus. Primary target: To reduce the production of gastric acid. But the surgeons observed a loss of appetite, the patients ate less calories and lost weight – at least until the body adjusted to the new situation by anti regulation mechanisms.
Shock therapy for hungry stomachs
The US-company EnteroMedics has taken this old surgeon's observations to heart and developed a pacemaker attacking the Nervus vagus with extremely high frequent electronic impulses.
That way the parasympathetic main innovator of the upper gastrointestinal system is supposed to be paralyzed – not completely but intermittently. The hope: that's how the anti-obese effect of the surgical vagectomy can be achieved without those accustoming effects usually showing after surgery. The method is planned to be an alternative to stomach resections and gastric banding which limit the ingestion by surgical coercive measures.
Compared to those approaches, the method called VBLOC (Vagal Blocking for Obesity Control) has to be considered a rather tender one. Just five small cuts for a minimal-invasive surgery and the two electrodes are connected laparoscopically to both sides at the Vagus nervus, i. e. at the Vagus main branches close to the phrenic at the gastro-esophageal exit. Similar to a cardiac pacemaker the cable leads to an implant called "Neuro-regulator". This can be syntonized by the physician wireless, but requires an inductor coil. With a diameter of twelve centimeters after all, it sits on the skin and is connected by cable to a controller the size of a phone receiver containing not much more than a rechargeable battery. The controller itself can be attached to a belt.
Muscles, adenoids, epithelia: All listen to the Nervus vagus
Currently clinical studies in several centers specializing in Adiposity are testing the effectiveness of the new method. Whoever is living outside the US and wants to participate in the studies can get registered online to get information. Naturally there is no guarantee that this will work out. A certain scepticism is appropriate: According to EnteroMedics no studies have been made so far with any comparable basic approach. But good old vagectomy was made on obese patients with the target of weight reduction before and condemned because effects did not last.
If they succeed though to breach the accustoming effect by intermittent stimulation, then quite a bit speaks for this new method. Because the Nervus vagus is participating in several processes and blocking them could reduce the appetite. Vagus activity benefits the expansion of the stomach during ingestion thus making room for more food. It also stimulates secretion of gastric acid and digestion enzymes. So a blockage of the Vagus could – with a detour via decrease of neurohumoral impulses – have a positive influence on the central regulation of appetite in the Hypothalamus.
All the eggs in one basket
Regulation of appetite and the share of the Nervus vagus in it is not really known in detail. The whole thing is sort of vabanque gambling for EnteroMedics and the company gambles for high stakes: To push things, the company plans to acquire 86.25 million US Dollars with an initial publics offering on the stock market. The example of the biotech company Paion currently shows that this is a risky thing for potential investors. Paion's major product, the active agent Desmoteplase for lyse therapy for stroke patients failed in a phase III-study and sent the Paion stocks down the tube by 75 percent just now in early June.