Direct Link Found Between 'Hunger Hormone' And 'Depression'
The American researchers say that they already knew that the level of ghrelin known as "hunger hormone" increases when a person doesn’t eat food and this very hormone helps in defending against symptoms of stress induced depressiondefine and anxiety.
The researchers conducted the experiment on mice and found that the increased levels of the hormone showed fewer signs of depression and anxiety.
Senior author of the study, Dr. Jeffrey Zigman, assistant professor of internal medicine and psychiatry at UT Southwestern said, "Our findings in mice suggest that chronic stress causes ghrelin levels to go up and that behaviors associated with depression and anxiety decrease when ghrelin levels rise. An unfortunate side effect, however, is increased food intake and body weight."
Dr. Jeffrey Zigman and team knew beforehand that not eating food causes the gut to produce ghrelin, which sends hunger signals to the brain. This led them to suggest blocking ghrelin as an approach to weight control.
"However, this new research suggests that if you block ghrelin signaling, you might actually increase anxiety and depression, which would be bad," Dr. Zigman said.
In the experiment the researchers restricted the food intake of laboratory mice for ten days, causing their ghrelin levels to rise. When compared with control group, mice who had free access to food, the calorie restricted mice showed lower levels of depression and anxiety when subjected to mazes and other standard behaviour tests.
The research, published in the journal Nature Neuroscience found that mice genetically engineered to be unable to respond to ghrelin. When mice were made to eat a specific calorie diet they did not experience the antidepressant or anti-anxiety like effects.
Same results were found when the researchers induced higher ghrelin levels by subjecting the mice to daily bouts of social stress. The team found that those mice that could not respond to ghrelin had higher levels of depression like symptoms than the normal mice.
He said, "We're very interested to see whether ghrelin treatment could help people with anorexia nervosa, with the idea being that in a certain population, calorie restriction and could have an antidepressant effect and could be reinforcing for this illness."
When upset, stress eaters often crave sweets, "junk food" or "comfort food." At times, a person may feel a loss of control over their eating, resulting in shame or guilt.