How Gut Neuropeptides Work Together: VIP Triggers Contractions, Dynorphin Shuts Them Down
VIP caused gut muscle contractions through acetylcholine and substance P, but dynorphin and somatostatin completely abolished these contractions.
Quick Facts
What This Study Found
VIP (20 nM-1 microM) induced neurogenic gut contractions via acetylcholine and substance P. Dynorphin (100 nM) and somatostatin (60 nM) abolished these contractions.
Key Numbers
How They Did This
Guinea pig ileal longitudinal muscle strips in organ baths. VIP-induced contractions measured with and without nerve blockers, receptor antagonists, dynorphin, and somatostatin.
Why This Research Matters
This shows how multiple neuropeptides interact in the gut nervous system. Dynorphin's ability to shut down VIP-driven contractions explains part of how opioids cause constipation.
The Bigger Picture
This explains part of why opioid drugs cause constipation — dynorphin and similar opioids shut down the nerve-driven gut contractions that move food along. Understanding these interactions could help develop opioid pain medications with fewer gut side effects.
What This Study Doesn't Tell Us
In vitro study in guinea pig gut. Isolated tissue may not reflect intact gut physiology. Species differences in gut pharmacology exist.
Questions This Raises
- ?Can we design opioid pain drugs that don't activate gut dynorphin receptors?
- ?Is dysregulation of the VIP-dynorphin balance involved in irritable bowel syndrome?
Trust & Context
- Key Stat:
- Complete abolition Dynorphin at just 100 nM completely blocked VIP-induced gut contractions
- Evidence Grade:
- Preliminary — in vitro study using isolated guinea pig intestinal muscle strips. Clear pharmacological results but removed from intact gut physiology.
- Study Age:
- Published in 1992 (34 years ago). The role of opioids in gut motility is now well-established and clinically relevant.
- Original Title:
- Vasoactive intestinal polypeptide induces neurogenic contraction of guinea-pig ileum. Involvement of acetylcholine and substance P.
- Published In:
- Regulatory peptides, 38(2), 155-64 (1992)
- Authors:
- Katsoulis, S, Schmidt, W E(2), Clemens, A, Schwörer, H, Creutzfeldt, W
- Database ID:
- RPEP-00239
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why do opioids cause constipation?
This study shows part of the mechanism: dynorphin (a natural opioid) completely shuts down nerve-driven gut contractions. Opioid drugs activate these same pathways, slowing gut movement and causing constipation.
What is VIP?
Vasoactive intestinal polypeptide is a signaling molecule in the gut's nervous system. It triggers muscle contractions that help move food through the intestines, working through acetylcholine and substance P release.
Read More on RethinkPeptides
Cite This Study
https://rethinkpeptides.com/research/RPEP-00239APA
Katsoulis, S; Schmidt, W E; Clemens, A; Schwörer, H; Creutzfeldt, W. (1992). Vasoactive intestinal polypeptide induces neurogenic contraction of guinea-pig ileum. Involvement of acetylcholine and substance P.. Regulatory peptides, 38(2), 155-64.
MLA
Katsoulis, S, et al. "Vasoactive intestinal polypeptide induces neurogenic contraction of guinea-pig ileum. Involvement of acetylcholine and substance P.." Regulatory peptides, 1992.
RethinkPeptides
RethinkPeptides Research Database. "Vasoactive intestinal polypeptide induces neurogenic contrac..." RPEP-00239. Retrieved from https://rethinkpeptides.com/research/katsoulis-1992-vasoactive-intestinal-polypeptide-induces
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkPeptides research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.