By Rachel Ehrenberg, Science News
A nip of Pernod or Ouzo before dinner to stimulate the appetite may be a sound strategy.
When mouse gut cells are stimulated with bitter compounds they trigger secretion of a hunger hormone, researchers report online January 18 in the Proceedings of the National Academy of Sciences.
Whetting the appetite with a before-dinner drink, or aperitif—from the Latin aprire, to open—has long been associated with improved digestion. The often bitter drinks typically contain a secret mixture of herbs and spices, sometimes to deliberately quell the taste of another common aperitif ingredient—quinine.
Quinine is one of a number of compounds that stimulate the bitter taste receptors—cells that, in the mouth, are seen as a first line of defense against ingesting toxins. So scientists thought that eating such compounds would inhibit appetite, not rev it up.
But when mice were fed a bitter mixture, their levels of the hunger hormone ghrelin spiked, a research team from the Catholic University of Leuven in Belgium reports. These mice then went on a half-hour eating binge, unlike counterparts that had impaired machinery for sensing bitter compounds. Oddly, this binge was followed by several hours of fasting, and experiments revealed a delay in digestion of the large meal.
“Perhaps everything looks better when ghrelin levels are high—it stimulates you to eat food and then stop, perhaps preventing you from overeating,” says study leader Inge Depoortere, a specialist in gut-hormone physiology.
The bitter compounds do appear to inhibit the contractile muscles that help move stuff from the stomach to the intestine. This might be a mice-specific mechanism—since the rodents don’t have a vomiting reflex, the delay in digestion may prevent toxic compounds that make it past the mouth from being fully absorbed. But it might it might be part of an even broader phenomenon—scientists recently reported that breathing bitter compounds relaxes the muscles cells that squeeze an airway shut (SN: 11/20/10, p. 8).
The research is intriguing and highlights how much there is to learn about the molecules and biochemical pathways that regulate eating, says Catia Sternini of the digestive diseases division at the UCLA School of Medicine. There are numerous cells that respond to the enormous array of compounds that travel through the gut. Teasing out which cells do what, and when, may eventually help researchers treat gastrointestinal or eating problems in people, but much work needs to be done before that drink is in hand.
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