Ghrelin From the Stomach Stimulates Appetite and Opposes Leptin's Satiety Signal | Research

The takeaway

Ghrelin, the stomach-derived GH secretagogue ligand, stimulated food intake and body weight gain in rats through vagus nerve and hypothalamic pathways, acting as an appetite signal that opposes leptin.

Hunger hormone identified
Ghrelin from the stomach signals hunger through the vagus nerve and hypothalamus, directly opposing leptin's satiety message

What the researchers found

Ghrelin stimulated food intake and weight gain in rats through vagal and hypothalamic mechanisms, with ghrelin levels suppressed by feeding and increased by leptin, establishing the ghrelin-leptin axis for appetite regulation.

Why it matters

Identifying ghrelin as the stomach's hunger signal complemented leptin's satiety signal, completing the peripheral hormonal framework for appetite regulation and opening new obesity treatment targets.

How the study worked

Animal study examining ghrelin's effects on food intake, body weight, and interactions with leptin and vagus nerve signaling in rats. Central and peripheral ghrelin administration tested.

What this study cannot tell us

Rat study. Acute ghrelin effects may differ from chronic signaling. The exact mechanisms of ghrelin-leptin interaction were not fully resolved.

How to read the evidence

Moderate evidence from comprehensive animal studies characterizing ghrelin's appetite and energy balance effects.

When this study was published

Published in 2001. Ghrelin is now well-established as a key hunger hormone, with ghrelin-based drug development ongoing for obesity and cachexia.

The bigger picture

Ghrelin's identification as the hunger hormone completed the leptin-ghrelin axis, providing a bidirectional hormonal framework for understanding appetite. This has driven drug development targeting both sides of this system.

Questions still open

Can ghrelin antagonists treat obesity?
Does ghrelin resistance develop with chronic overeating?
How do ghrelin levels change with bariatric surgery?

Common questions

What is ghrelin?

Ghrelin is a hormone produced by the stomach that signals hunger to the brain. It's the opposite of leptin (which signals fullness). Together, they form the body's main hormonal system for controlling appetite.

Could blocking ghrelin help with weight loss?

In theory, yes — blocking the hunger signal should reduce appetite. Ghrelin antagonists are being developed for obesity. However, the body's appetite system has many backup mechanisms, which complicates this approach.

Read the original research

Ghrelin is an appetite-stimulatory signal from stomach with structural resemblance to motilin.

Gastroenterology, 120(2), 337-45

View on PubMed ↗

Citation

Asakawa, A; Inui, A; Kaga, T; Yuzuriha, H; Nagata, T; Ueno, N; Makino, S; Fujimiya, M; Niijima, A; Fujino, M A; Kasuga, M. (2001). Ghrelin is an appetite-stimulatory signal from stomach with structural resemblance to motilin.. Gastroenterology, 120(2), 337-45.