Hunger hormone 'increases' during stress

New York, Jun 16 (PTI) Ever wondered why you tend
to overeat when you are stressed? Well, a study has the answer
finally -- it's due to "hunger hormone" ghrelin which also has
an "anti-depressant" effect.

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.

Now, a team at the University of Texas has found that
ghrelin increases during chronic stress which in turn triggers
feelings of hunger in the brain -- however, behaviours linked
to anxiety decrease when the "hunger hormone" levels rise.

According to lead researcher Jeffrey Zigman, "Our
findings suggest that chronic stress causes ghrelin levels to
go up and behaviours associated with depression and anxiety
decrease when ghrelin levels rise. An unfortunate side effect
is increased food intake and body weight."

The researchers have based their findings on an
analysis of rodents -- they restricted the food intake of the
mice for ten days, thereby causing the ghrelin levels of the
animals to quadruple.

Compared with rodents who had free access to food,
their calorie-restricted counterparts showed lower levels of
anxiety when being subjected to mazes and other behaviour
tests, the 'Nature Neuroscience' journal reported.

The team also looked at mice genetically engineered to
be unable to respond to ghrelin. When they're fed a restricted
calorie diet, they did not experience the antidepressant or
anti-anxiety effects.

The researchers found the same thing when they induced
higher ghrelin levels by subjecting the mice to stress. Those
who couldn't respond to ghrelin had higher depression levels
like symptoms than the normal mice.

"Our findings support the idea that these hunger
hormones don't do just one thing; rather, they coordinate an
entire behavioural response to stress and probably affect
mood, stress and energy levels," the 'ScienceDaily' quoted the
study's lead author Dr Michael Lutte as saying.