Researchers suggest that targeting the NT peptide could be a promising treatment strategy for obesity.
As such, the high rates of obesity in the U.S. mean the condition has become a major public health concern.
While overeating and lack of physical activity are considered the primary causes of overweight and obesity, researchers are increasingly finding there may be other factors at play.
In a new study published in the journal Nature, researchers reveal how a peptide called neurotensin (NT) promotes obesity by boosting fat absorption.
NT is primarily produced in the central nervous system and gastrointestinal tract. The peptide is involved in the regulation of fat metabolism; it is released following fat consumption and promotes fat absorption in the intestine.
Previous studies have suggested a link between NT and increased growth of some cancers, while other research has indicated that high fasting levels of pro-NT - a hormone that is a precursor to NT - is linked to the development of cardiovascular disease and breast cancer.
Study leader Dr. Mark Evers, director of the University of Kentucky Markey Cancer Center, and colleagues say their findings indicate that NT could be a promising target for the treatment of obesity.
Obesity risk doubled with high pro-NT levels
For their research, the team analyzed data of 4,632 men and women who were part of the Malmö Diet and Cancer Study and who were followed up for an average of 16.5 years.
Compared with normal-weight, healthy subjects, individuals who were obese and had insulin resistance were found to have significantly higher levels of fasting pro-NT.
Furthermore, the researchers found that individuals who had the highest levels of pro-NT were at twice the risk of becoming obese later in life than those who had the lowest levels of the hormone.
To investigate the possible mechanisms behind the link between NT and obesity, the researchers analyzed mouse models that were deficient in NT.
After feeding these mice a high-fat diet, the team found that the rodents absorbed less fat than normal mice. What is more, the NT-deficient mice were less likely to develop insulin resistance and fatty liver disease - conditions linked to high fat intake.
Further investigation in both mice and fruit flies revealed that NT blocks the activity of an enzyme called AMPK, which plays a major role in metabolism regulation.
Overall, the researchers believe their findings suggest that NT could be a biomarker for obesity, and inhibiting the peptide could offer a promising treatment for the condition.
"Our findings have redefined how we view the role of NT. NT appears to be a metabolically 'thrifty' peptide which increases the absorption of ingested fats; however, with the abundance of fats in typical Western diets, NT can have a detrimental effect by contributing to increased obesity and related metabolic disorders."
Dr. Mark Evers
Furthermore, Dr. Evers notes that, given the association between NT and increased cancer growth, their findings might explain why obese individuals are at greater cancer risk than non-obese individuals.
The team plans to investigate this possible association in future research.