Majority believe that a plate of food that looks delicious and mouthwatering makes us want to eat more. But how much would you eat?Obviously until our tummy is full.But we do commonly come across people who continue to eat even when the button of their shirts could burst open anytime. Scientists from UT Southwestern Medical Center have been recently involved in a research to explain why some people eat even on a full stomach.
Prior research has revealed that ghrelin is a key hormone which is involved in hunger.An evident increase in the amount of this hormone during mealtime increases our appetite through its effects on the brain.The latest research conducted in mice however shows that ghrelin might also work on the brain to make some people eat “pleasurable” foods even on a full stomach. Dr. Jeffrey Zigman, assistant professor of internal medicine and psychiatry at UT Southwestern and co-senior author of the study appearing online and in a future of Biological Psychiatry explains this phenomenon in terms of Rewards.”Rewards” generally can be defined as things that make us feel better and give us sensory pleasure and motivate us to obtain more of it.Similar is the case with ghrelin.It increases specific rewarding aspects of eating. Dr. Mario Perello, postdoctoral researcher in internal medicine is the lead author of the current study which aims to find out “why someone who is stuffed from lunch still eats – and wants to eat – that high-calorie dessert.” For this two standard behavioral tests were conducted. In the first, they evaluated whether mice that were fully sated preferred a room where they had previously found high-fat food over one that had only offered regular bland chow. They found that when mice in this situation were administered ghrelin, they strongly preferred the room that had been paired with the high-fat diet. Mice without ghrelin showed no preference. “We think the ghrelin prompted the mice to pursue the high-fat chow because they remembered how much they enjoyed it,” Dr. Perello said. “It didn’t matter that the room was now empty; they still associated it with something pleasurable.” The researchers also found that blocking the action of ghrelin, which is normally secreted into the bloodstream upon fasting or caloric restriction, prevented the mice from spending as much time in the room they associated with the high-fat food. For the second test, the team observed how long mice would continue to poke their noses into a hole in order to receive a pellet of high-fat food. “The animals that didn’t receive ghrelin gave up much sooner than the ones that did receive ghrelin,” Dr. Zigman said. Humans and mice share the same type of brain-cell connections and hormones, as well as similar architectures in the so-called “pleasure centers” of the brain. In addition, the behavior of the mice in this study is consistent with pleasure- or reward-seeking behavior seen in other animal studies of addiction, Dr. Zigman said. The next step, Dr. Perello said, is to determine which neural circuits in the brain regulate ghrelin’s actions.
