Obesity vaccine hits obstacle

In an effort to combat obesity, scientists are exploring repressing ghrelin, a stomach hormone the levels of which rise and fall with hunger. The problem? A study shows ghrelin plays a vital role in regulating acute stress and offers potential therapeutic efficacy in human mood and stress disorders.

The study, published in Biological Psychiatry, shows that ghrelin increases anxiety in calm environments, but reduces anxiety in stressful situations. Decreases in ghrelin also led to decreases in food intake and increases in energy expenditure in animal tests, which is why researchers are exploring regulating the hormone for an obesity vaccine.

Researchers put mice that had been genetically modified to lack ghrelin through a number of behavioral tests to monitor their anxiety levels. Then, the researchers put the mice through acute stress and repeated the tests. The results were then compared with those of normal mice. The results showed that under acute stress, mice without ghrelin receptors experienced extreme levels of anxiety. Conversely, the normal mice responded to the stress with the release of ghrelin and lower levels of anxiety.

And, as The Atlantic reports, chronic stress could lead to compensatory overeating, counteracting the vaccine's effects. Something to weigh as the search for an obesity vaccine continues.

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