Impulsive Eating and Melanin-Concentrating Hormone Signaling

The Link Between Impulsivity and Eating Behavior

Researchers have identified a melanin-concentrating hormone (MCH) signaling pathway in the brain that plays a significant role in regulating impulsive eating. Impulsivity is associated with various issues, including overeating, addiction to drugs or gambling, attention deficit disorder, and Parkinson’s disease. Many individuals have experienced moments of giving in to intense food cravings, often followed by regret. While occasional impulsive eating may not have serious consequences, frequent indulgence can lead to weight gain, obesity, diabetes, and disordered eating patterns.

Understanding Brain Circuits and Treatment Development

As scientists delve deeper into the brain circuitry associated with impulsive behavior and neuroplasticity, new treatment options for managing overeating may emerge. A recent study published in *Nature* has shed light on a central nervous system (CNS) pathway involving MCH, revealing its influence on impulsive eating in rats.

Study Findings on MCH Signaling Pathway

The MCH molecule, a peptide consisting of 19 amino acids, is produced in the hypothalamus and is crucial for various behavioral and physiological processes, including eating. The hippocampus, responsible for memory and learning, is particularly responsive to internal chemical signals and receives MCH signals from the hypothalamus.

In the study, researchers trained rats to wait 20 seconds between lever presses to receive a high-fat and high-sugar pellet. If a rat pressed the lever too soon, it had to wait an additional 20 seconds for the reward. Advanced chemogenetic and pharmacological techniques were then employed to activate the CNS MCH signaling pathway in the rats’ brains. The frequency of lever presses was measured post-activation to gauge impulsivity.

Results and Implications

The results indicated that activating the MCH signaling pathway led to increased impulsive behavior in rats, without affecting their caloric intake, hunger, desire for palatable food, or locomotor activity. The researchers propose that the MCH signaling pathway likely amplifies impulsive behavior by impairing the rats’ ability to restrain themselves from seeking food and diminishing their consideration of the consequences of their actions.

Interestingly, the study revealed that impulsivity increased when the MCH signaling pathway was entirely disrupted. This finding suggests that the MCH signaling pathway operates bidirectionally, where both increased (upregulation) and decreased (downregulation) signaling can heighten impulsive behavior. Further research is necessary to explore the interaction between MCH signaling variations.

Context and Future Directions

These findings align with previous research linking the ventral hippocampus to impulsivity and food-motivated behaviors. While it was known that elevated MCH levels in the brain could boost food intake, this study is the first to demonstrate MCH’s role in mediating impulsive behavior. Consequently, the MCH signaling system emerges as a promising target for obesity drug development, potentially offering insights into treating other impulsive behaviors.

About the Author

Written by Maria-Elena Bernal B.Sc. (Hons)

References

Noble, E. E., Wang, Z., Liu, C. M., Davis, E. A., Suarez, A. N., Stein, L. M., … Kanoski, S. E. (2019, October 29). Hypothalamus-hippocampus circuitry regulates impulsivity via melanin-concentrating hormone. Retrieved from https://www.nature.com/articles/s41467-019-12895-y#citeas.
University of Georgia. (n.d.). Researchers discover brain circuit linked to food impulsivity. Retrieved from https://www.eurekalert.org/pub_releases/2019-12/uog-rdb121119.php.
Image by Ryan McGuire from Pixabay.