Human eating habits are primarily driven by two motivations: satisfying hunger or seeking pleasure. While eating to fulfill hunger is essential, indulging solely for pleasure can lead to overeating. This behavior is often linked to obesity and other metabolic disorders. Understanding the brain mechanisms that regulate these two types of eating behaviors is crucial for preventing these health issues.
Illustrative image from Pixabay
The brain plays a central role in managing eating habits, regulating hunger, and responding to pleasurable food stimuli. Among the neural players involved, proenkephalin (Penk)-labeled neurons, an endogenous opioid, are known for their role in body weight regulation. Prior to this study, researchers suspected these neurons influenced both hunger-driven and pleasure-driven eating, but without understanding their specific mechanisms.
To better comprehend this phenomenon, a research team conducted a study on mice, focusing on Penk neurons in a brain region called the diagonal band of Broca (DBB). They utilized genetic manipulation techniques to specifically activate these neurons and observe the effects on the mice's eating behaviors. They measured differences in food consumption in response to hunger and to particularly pleasurable foods rich in fats and sugars.
The results revealed that activating Penk neurons in the DBB resulted in opposing effects on the two types of eating. Activating these neurons increased hunger-driven eating while reducing pleasure-driven eating. The researchers were surprised by this finding, as other groups of neurons had previously shown similar effects on both types of eating behaviors.
The researchers discovered that these Penk neurons project to two distinct brain regions, accounting for the contrasting effects. One subpopulation of neurons projects to the paraventricular nucleus of the hypothalamus, activating during fasting periods to promote hunger-driven eating. Another subpopulation projects to the lateral hypothalamus, inhibiting the consumption of high-fat and high-sugar foods, moderating pleasure-driven eating.
These findings alter the understanding of the brain mechanisms involved in obesity and open new avenues for research and treatment of this public health issue. Researchers are now considering targeting these neural circuits to develop more effective obesity treatments. A better understanding of these mechanisms could also help promote healthier eating habits by balancing food needs and pleasure desires.
Article author: Cédric DEPOND