Do you still find yourself going for that extra piece of chocolate fudge cake even though you are not feeling hungry? Well, that might be due to the absence of a hormone in your brain which is making you eat more just for the pleasure of it.
According to a new Rutgers Robert Wood Johnson Medical School study published in Cell Reports, it was found that when the hormone called glucagon like peptide-1 (GLP-1) was reduced in the central nervous system of laboratory mice, they overeat and ate more high-fat food.
Advertisement"The mice in which the GLP-1 deficiency was induced ate beyond the need for calories and showed an increase preference for high-fat food," said Vincent Mirabella, a medical school and doctoral student who co-authored the study. Whereas when the GLP-1 signaling system in the brain of the mice was enhanced, they were able to block the preferences of high-fat foods.
Along with many other functions in the body, the GLP-1 peptides play a role in regulating the body's eating behavior. These peptides are small sequences of amino acids that are secreted from cells in both the small intestine and the brain. They are supposed to let our brain know when we are satisfied and stop eating.
It has still been unclear as to how the GLP-1 released in the brain contributes to appetite regulation, said Rutgers scientists. But this is not the only reason why people overeat, the study shows new evidence that targeting neurons in the mesolimbic dopamine system is a better way to control overeating and obesity with lesser side effects than targeting the whole body. The mesolimbic dopamine system, also known as reward pathway, plays a major role in the neurobiology of addiction. This system is the most significant neural pathway of the brain where changes occur in all known forms of addiction.
When the GLP-1 hormone is activated in the mesolimbic system, it hindered the communication between neurons which interact to control reward behaviors, including eating. The result of the study was that the mice consumed less food altogether and importantly, lost the preference for high fat food.
"These are the same areas of the brain that controls other addictive behaviors like drug and alcohol abuse and nicotine addiction," said senior author and assistant professor Zhiping Pang. "We believe that our work has broad implications in understanding how GLP-1 functions to influence motivational behaviors."
The central nervous system controls the eating behaviors such as why we eat, how much we eat and when we stop eating which enables the body to respond to its environment. This is the reason why it is necessary to understand the motivation behind 'hedonic hunger', the drive to eat for pleasure instead to gain energy. The motivational factors and physiological factors will provide a better understanding of modern eating habits, such as why a dysfunction may occur and can provide insights on more targeted therapies.
There are very limited effective therapies for treating obesity. A drug that was recently approved by the US Food and Drug Administration is now being used as treatment for obesity. The drug mimics the GLP-1 hormone which was initially used to improve glucose tolerance for those with type 2 diabetes. However this injectable medication that targets the whole body, can possibly cause serious side effects including pancreatitis, gall bladder disease and kidney problems.
"Over eating, which causes obesity, can be considered a food addiction, a neuropsychiatric disorder. By finding out how the central nervous system regulates food intake behavior via GLP-1 signaling, we may be able to provide more targeted therapy with fewer side effects," said Pang.