A hormone plays a crucial role

Dec 28, 2009 19:01 GMT  ·  By
Drs. Mario Perello, Michael Lutter, Jeffery Zigman (from left) have been the leaders of the new UT Southwestern research
   Drs. Mario Perello, Michael Lutter, Jeffery Zigman (from left) have been the leaders of the new UT Southwestern research

The human brain is designed in such a way that, after we eat as much as we need, it sends commands that let us know we're full. In some cases, however, this mechanism malfunctions, and people continue to eat various foods even after they no longer need them. Now, investigators at the University of Texas Southwestern (UT Southwestern) Medical Center believe they may have found the culprit, in the so-called hunger hormone ghrelin. The research has also demonstrated that the chemical only acts in some people, and that it only makes them eat pleasurable foods.

“What we show is that there may be situations where we are driven to seek out and eat very rewarding foods, even if we're full, for no other reason than our brain tells us to,” the co-senior author of the study, Dr. Jeffrey Zigman, explains. He is also a UT Southwestern assistant professor of internal medicine and psychiatry. The paper detailing the new findings currently appears online in the scientific journal Biological Psychiatry, and is scheduled to be published in print too, in a future issue of the publication.

In previous works, it was found that ghrelin was one of the chemicals that boosted the response of reward and pleasure centers of the brain, but in people who consumed alcohol or drugs. Zigman's group is the first to propose that the hormone also plays an important part in stimulating the reward centers of the brain when people eat pleasurable foods too. Rewards “give us sensory pleasure, and they motivate us to work to obtain them. They also help us reorganize our memory so that we remember how to get them,” Zigman adds.

The team leader reveals that the next goal in the investigation is to determine the exact neural pathways that the hormone employs in its action. This knowledge could allow the team to propose the development of new types of drugs, or other therapies, that would block the chemical's actions and therefore make people feel full after eating just the right amount of food they need. “The animals that didn't receive ghrelin gave up [extra food] much sooner than the ones that did receive ghrelin,” Zigman concludes.