Which gastrointestinal hormone is specifically known for decreasing appetite?

The correct choice is oxyntomodulin, which is a gastrointestinal hormone that has been shown to play a significant role in regulating appetite. Oxyntomodulin is secreted by the intestinal L-cells in response to nutrient intake. It functions by signaling the brain to reduce hunger, effectively decreasing appetite.

In addition to appetite suppression, oxyntomodulin also has metabolic effects including the stimulation of energy expenditure. This makes it an intriguing target for research into obesity treatment, as it addresses both appetite control and energy balance.

While other hormones such as GLP-1 and PYY are also associated with appetite regulation, oxyntomodulin is particularly distinct in its effects. GLP-1 enhances insulin secretion and improves glycemic control, which contributes indirectly to appetite suppression, but its primary role is more centered on glucose metabolism. Similarly, while PYY is an important hormone that also decreases appetite after meals, its effects are more prominent in the context of postprandial signaling rather than a direct appetite suppressant like oxyntomodulin. Insulin primarily regulates glucose homeostasis and has appetite-modulating effects but is not considered a dedicated appetite suppressant in the same way oxyntomodulin is.

Thus, oxyntomodulin stands out as a specialized