DALLAS – June 15, 2008 – New research at UT Southwestern Medical Center may explain why some people who are stressed or depressed overeat.
While levels of the so-called "hunger hormone" ghrelin are known to increase when a person doesn't eat, findings by UT Southwestern scientists suggest that the hormone might also help defend against symptoms of stress-induced depression and anxiety.
"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," said Dr. Jeffrey Zigman, assistant professor of internal medicine and psychiatry at UT Southwestern and senior author of a study appearing online today and in a future print edition of Nature Neuroscience.
Dr. Michael Lutter, instructor of psychiatry at UT Southwestern and lead author of the study, said, "Our findings support the idea that these hunger hormones don't do just one thing; rather, they coordinate an entire behavioral response to stress and probably affect mood, stress and energy levels."
What I wonder: If you are under stress and ghrelin goes up then do you get more stress-reduction benefit from ghrelin if you manage to refrain from eating more? Does weight gain cause a decrease in ghrelin and therefore less stress-reduction benefit from ghrelin?
Ghrelin reduces the stress reaction from getting bullied.
To test whether ghrelin could regulate depressive symptoms brought on by chronic stress, the researchers subjected mice to daily bouts of social stress, using a standard laboratory technique that induces stress by exposing normal mice to very aggressive "bully" mice. Such animals have been shown to be good models for studying depression in humans.
The researchers stressed both wild-type mice and altered mice that were unable to respond to ghrelin. They found that after experiencing stress, both types of mice had significantly elevated levels of ghrelin that persisted at least four weeks after their last defeat encounter. The altered mice, however, displayed significantly greater social avoidance than their wild-type counterparts, indicating an exacerbation of depression-like symptoms. They also ate less than the wild-type mice.
Avoid the alpha male bullies. Or beat them up. The health costs of being a beta male are very real.
|Share |||Randall Parker, 2008 June 19 10:44 PM Brain Appetite|