There are several factors that trigger almost everyone to be interested in eating even when full or not hungry. The whole food industry itself is built on tempting individuals to eat, whether needed or not, through aroma, appearance, packaging and, and emotional associations. Some wonder if eating despite being full has to do with the taste or the environment that encourages indulgence. In a new study, researchers of University of Michigan, explore group of brain cells which drive eating past the point of fullness. They carried out the study on mice which the scientist believed to better understand similar mechanism in human. It shows that two brain cells battle over to control the feeding behavior, where the signals to stop eating is not powerful enough to function against the strong urge to eat.
The study also showed the involvement of brain’s own natural opioid system which when blocked by a drug called naloxone can halt over-eating. According to Prof. Huda Akil, a neuroscientist at the University of Michigan, their findings could help to promote the fight against the global obesity epidemic. In a mouse model, the researchers studied feeding behavior being linked to two clusters of brain cells: pro-opiomelanocortin (POMC) and Agouti-Gene-Related Peptide (AgRP). These group of cells are located adjacent to each other within a region called arcuate nucleus or Arc of the brain.
In previous studies, including work of several U-M laboratories, the roles of POMC and AgRP neurons in feeding behavior have been demonstrated, especially when the food is scarce for a long time since last eating. However, the interaction of these two neurons remained unclear.
According to currently study published in ‘Proceedings of the National Academy of Science’, researchers used optogenetics technique to stimulate and deactivate POMC in mice by using laser light, considering the earlier known role of these neurons in feeding behavior.
The results showed that stimulation of PMOC cells also activated the neighboring AgRP cells. These two groups of cells have found to be derived from same parent cells during embryonic development. Therefore, activation of PMOC neurons by the researchers also captured the AgRP cells.
Huda Akil and colleagues found that when both the cells were stimulated, AgRP had more influence on the eating behavior and over-powered PMOC nerve cells which is responsible for stopping the urge to eat. Further, c-fos activation technique was used to investigate the signals that are effects of activating these two nerve cells.
In the final set of experiments, activation of AgRP has found to facilitate the brain’s opioid system. Administering the rodents with opioid blocker drug naloxone stopped the feeding behavior, revealed the researchers. This suggests that the brain’s opioid system may play an important role in wanting to eat beyond the need.