Gut Peptide Motilin Proven to Directly Stimulate Appetite Through the Vagus Nerve

Researchers simultaneously monitored gastric contractions and food intake in conscious house musk shrews. Plasma motilin levels were measured during different phases of the migrating motor complex. Intravenous motilin and ghrelin were administered during phase I contractions to test feeding effects. Vagotomy was performed to test nerve dependency. Brain c-Fos immunohistochemistry identified activated neurons in appetite-regulating brain regions.

Motilin has long been known to trigger stomach contractions and hunger sensations, but direct evidence that it regulates food intake was lacking — partly because rats and mice lack functional motilin genes. This study fills that gap, establishing motilin as a genuine appetite-regulating peptide hormone and identifying the neural pathway (vagus nerve → brainstem → hypothalamus) through which it works. This positions motilin as a potential therapeutic target for appetite disorders, adding to the growing toolkit of gut peptides that could be harnessed for metabolic medicine.

The discovery that motilin directly regulates appetite through a defined neural pathway adds a new player to the gut-brain peptide axis alongside ghrelin, GLP-1, and PYY. As the pharmaceutical industry develops peptide-based treatments for obesity and appetite disorders, understanding motilin's role could lead to new therapeutic approaches — or help explain why some patients with gastric motility disorders also have appetite dysregulation.

The study used Suncus murinus (house musk shrew) rather than a more commonly studied animal, and results may not directly translate to humans. The relationship between motilin and food intake in humans requires clinical confirmation. The study focused on acute motilin administration rather than chronic effects. The comparison with ghrelin was limited and quantitative dose-response data were not fully detailed in the abstract.