Dr Jeffrey Zigman and his team UT Southwestern Medical Center in Dallas conducted an experiment where mice had their food intake restricted for 10 days. As a result, the mice's level of hunger hormone called ghrelin increased by four times. In comparison to the other group of mice who were not restricted of food, the first group showed lower levels of depression and anxiety during the tests.
Ghrelin is a hormone that signals about feeling of hunger, moving from the stomach to the brain. Blocking the response of the body to ghrelin is one of the common weight loss methods. However, as the findings indicate, this method may have an unwanted side effect, causing depression or other mood fluctuations.
During the experiment, scientists also examined the mice, who were genetically engineered to be responsive to ghrelin hormone. They were also restricted of food, but showed no antidepressant effect. This group of mice who where exposed to stress to increase their level of ghrelin hormone also did not show the same effect as normal mice.
The findings of the study suggest that chronic stress increases the level of ghrelin leading to lower levels of depression and anxiety. However, this may lead to increased food intake and body weight.
The results of the study may be helpful in designing a drug containing the hormone that will be used in treatment of the patients, who have such appetite disorders as anorexia.
Dr Zigman said that the results can be explained by the fact that during an evolution, hunger helped people stay composed in order to find food and survive.