Brain starved of hormone can spark binge eating

GLP-1 peptides are small sequences of amino acids that have various functions, including how our bodies regulate eating.

A hormone deficiency in the brain may be a reason why we eat even if we’re not hungry.

In a series of experiments carried out on laboratory mice, the Rutgers University team showed that reducing GLP-1 levels in the central nervous system correlates with an increase in appetite.

Absence of a hormone in the brain may trigger overeating in people who eat for pleasure rather than as a response to hunger, researchers say.

A new study published this week in the journal Cell Reports suggests that overeating happens when people don’t have enough of a hormone called glucagon-like peptide-1, or GLP-1. The mice with reduced levels of the hormone ate “beyond their need for calories” and consumed more high-fat food.

The Rutgers researchers say that it was previously not clear how the GLP-1 was released into the brain and how that contributed to regulation of appetite. This new study, though, reveals that activating the GLP-1 hormone in the mesolimbic system hindered communication between neurons which communicate to control reward behaviors, including eating. Thus, rodents deprived of this hormone started eating more and craving foods with a high fat content. This allows the central nervous system to adapt to outside environments and control how much a body consumes, according to the researchers.

Senior author Assistant Professor Zhiping Pang said: ‘These are the same areas of the brain that controls other addictive behaviours like drug and alcohol abuse and nicotine addiction. This study does have broad implications when it comes to understanding how the GLP-1 functions to influence motivational behaviors. “Conversely when we enhanced GLP-1 signaling in the brains of mice we were able to block the preference of high fat foods”.

The Rutgers scientists acknowledge there are other reasons why people overeat, but they said targeting these neurons might be a more effective way to curb obesity than current treatments. There are a lot of physiological and motivational factors that can provide a better understanding of eating habits of modern times, and why a dysfunction in this could occur, and then we can figure out how to treat these dysfunctions. A drug that mimics the GLP-1 hormone-used first to improve glucose tolerance for those with type 2 diabetes-and recently approved by the US Food and Drug Administration is now being used as a treatment for obesity.

The drug targets the whole body, which has side effects that can cause problems for the pancreas, gallbladder and kidney.

“By finding out how the central nervous system regulates food intake behaviour via GLP-1 signalling, we may be able to provide more targeted therapy with fewer side effects”, Pang said.