'Hunger hormone' fights depression

Ghrelin, the "hunger hormone", might help ward off stress-induced depression and anxiety but it will cause you to put on weight.

A new study on mice has found that chronic stress causes ghrelin levels to go up and that behaviours associated with depression and anxiety decrease when ghrelin levels rise.

An unfortunate side effect, however, is increased food intake and body weight, said Jeffrey Zigman of University of Tennessee, the study's senior author.

"Our findings support the idea that these hunger hormones don't do just one thing. Rather, they coordinate entire behavioural response to stress and probably affect mood, stress and energy levels," said Michael Lutter, co-author.

It is known that fasting causes ghrelin to be produced in the gastrointestinal tract and that the hormone then plays a role in sending hunger signals to the brain.

Research groups, including Zigman's, have suggested that blocking the body's response to ghrelin signals might be one way to help control weight by decreasing food intake and increasing energy expenditure.

"However, this new research suggests that if you block ghrelin signalling, you might actually increase anxiety and depression, which would be bad," Zigman said.

Zigman said the findings make sense when considered from an evolutionary standpoint. Earlier, the one common human experience was securing enough food to prevent starvation.

Our hunter-gatherer ancestors needed to be as calm and collected as possible when it was time to venture out in search of food or risk becoming dinner themselves, Zigman said.

Findings of the study are slated to appear in the forthcoming issue of the journal Nature Neuroscience.