Quick summary
Motilin is a 22-amino acid GI hormone regulating the migrating motor complex that clears the bowel between meals. Erythromycin acts as a motilin receptor agonist off-label; selective agonists are in gastroparesis trials.
Overview
Motilin is a 22-amino acid gastrointestinal hormone secreted by Mo/M cells of the upper small intestine during the fasting state. It is the primary regulator of the migrating motor complex (MMC), the coordinated pattern of gastrointestinal contractions that clear the bowel between meals. Motilin is released in approximately 100-minute cycles during fasting and is a key target for prokinetic drug development for gastroparesis and dysmotility.
Mechanism of action
Motilin binds the motilin receptor (MLNR), a class A GPCR predominantly expressed on smooth muscle cells and interstitial cells of Cajal in the GI tract. Receptor activation via Gq/11 coupling increases intracellular calcium and triggers coordinated smooth muscle contraction, initiating phase III of the migrating motor complex. Erythromycin and motilide antibiotics function as non-peptide motilin receptor agonists and are used off-label as prokinetics. The motilin-ghrelin receptor system shares structural homology, as both peptides derive from related gene families.
Dosing protocols
| Purpose | Route | Dosage | Frequency | Notes |
|---|---|---|---|---|
| GI motility research (animal) | intravenous | 1–30 pmol/kg/min | infusion per experimental protocol |
Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.
Research summary
Motilin's role in GI motility has been studied for decades. Clinical interest centers on developing selective motilin receptor agonists for diabetic gastroparesis and chronic intestinal dysmotility. Motilides (erythromycin-derived compounds) show clinical efficacy but are limited by tachyphylaxis. Small-molecule motilin receptor agonists (mitemcinal, camicinal) have advanced to phase II trials for gastroparesis with mixed results. Motilin also coordinates gastric acid secretion and gallbladder emptying during the interdigestive state.[1][2][3][4]
Evidence grading
Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.
Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data
Side effects
Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.
Common stacks
Peptides commonly paired with Motilin for synergistic effects.
Legal status
Motilin peptide is available for research use only and is not approved for human therapeutic use. Erythromycin (a non-peptide motilin receptor agonist) is FDA-approved as an antibiotic and used off-label as a prokinetic.
Sourcing & access
Research compound
Motilin is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).
Frequently asked questions
Motilin is a 22-amino acid gastrointestinal hormone secreted by Mo/M cells of the upper small intestine during fasting. It is the primary regulator of the migrating motor complex, the coordinated GI contractions that clear the bowel between meals, released in approximately 100-minute cycles.
Motilin binds the motilin receptor (MLNR), a class A GPCR on smooth muscle cells and interstitial cells of Cajal. Activation via Gq/11 coupling increases intracellular calcium and triggers coordinated smooth muscle contraction, initiating phase III of the migrating motor complex.
Motilin peptide is a research compound with side effects including GI cramping at supraphysiologic doses, nausea, and abdominal discomfort. Erythromycin, a non-peptide motilin receptor agonist used off-label, has an established clinical safety profile but is limited by tachyphylaxis.
Motilin receptor agonists are being developed for diabetic gastroparesis and chronic intestinal dysmotility. Small-molecule agonists like mitemcinal and camicinal have advanced to Phase II trials with mixed results, while motilide compounds derived from erythromycin show clinical efficacy but are limited by tolerance development.
Research references
- Motilin and its role in gastrointestinal motility: receptor pharmacologyPubMed
- Motilin receptor agonists in gastrointestinal dysmotility and gastroparesisPubMed
- Motilin signaling and the migrating motor complex: a physiological reviewPubMed
- Motilin and erythromycin-like prokinetics: mechanism and clinical applicationPubMed