Natural Brain Peptides Slow Gut Movement Through CB1 Receptors, Potentially Enabling Pain Relief Without GI Side Effects
Endogenous cannabinoid peptides (hemopressin and related molecules) slowed gastrointestinal motility through CB1 receptors when administered centrally in mice, but with lower potency than classical cannabinoids.
Quick Facts
What This Study Found
Hemopressin was identified as an endogenous peptide that acts on CB1 cannabinoid receptors. This study tested whether hemopressin and two related peptides (VD-Hpalpha and VD-Hpbeta) affect gastrointestinal motility when delivered directly to the brain.
All three peptides slowed gut movement across multiple measures: upper GI transit, colonic bead expulsion, and whole gut transit. These effects were blocked by the CB1 antagonist AM251 but not by the CB2 antagonist AM630, confirming they work through CB1 receptors.
The key finding for drug development was that these peptides were less potent at slowing the gut than the classical cannabinoid agonist WIN55,212-2. This lower potency on GI function could be therapeutically advantageous: cannabinoid peptides might provide pain relief at doses that do not significantly slow the gut, avoiding a common side effect of cannabinoid drugs.
Key Numbers
All three peptides slowed GI transit via CB1 receptors. Lower potency than WIN55,212-2 on all GI measures. Hpalpha and VD-Hpbeta inhibited whole gut transit at high doses. VD-Hpalpha did not affect whole gut transit. AM251 (CB1 blocker) reversed effects. AM630 (CB2 blocker) did not.
How They Did This
Mouse study using intracerebroventricular (i.c.v.) administration of hemopressin, VD-Hpalpha, VD-Hpbeta, and WIN55,212-2. GI motility measured via upper GI transit (charcoal meal), colonic bead expulsion, and whole gut transit (Evans blue dye). CB1 and CB2 receptor involvement tested with selective antagonists.
Why This Research Matters
Cannabinoid-based pain relievers often cause constipation and slowed digestion. If endogenous cannabinoid peptides can provide pain relief at doses below those that significantly affect the gut, they could offer a better therapeutic window than classical cannabinoids.
The Bigger Picture
The existence of endogenous cannabinoid peptides alongside the well-known lipid endocannabinoids (anandamide and 2-AG) suggests the endocannabinoid system is more complex than previously understood. Peptide cannabinoids could represent a new class of analgesic drugs with improved side effect profiles.
What This Study Doesn't Tell Us
Intracerebroventricular administration does not reflect practical drug delivery. Mouse GI physiology differs from humans. The lower potency could also mean lower analgesic efficacy, which was not tested in this study. Peptide stability and blood-brain barrier penetration pose challenges for drug development.
Questions This Raises
- ?Can cannabinoid peptides provide pain relief at doses that do not affect GI motility?
- ?Would systemically administered peptide analogs show the same favorable separation of effects?
- ?Could modified peptides be developed with improved stability and brain penetration?
Trust & Context
- Key Stat:
- Cannabinoid peptides slowed the gut less potently than classical cannabinoids
- Evidence Grade:
- Well-designed mouse study with multiple GI endpoints and selective receptor antagonists, but limited to central administration in rodents.
- Study Age:
- Published in 2016. Cannabinoid peptide research remains an active area of preclinical investigation.
- Original Title:
- Central administrations of hemopressin and related peptides inhibit gastrointestinal motility in mice.
- Published In:
- Neurogastroenterology and motility, 28(6), 891-9 (2016)
- Database ID:
- RTHC-01209
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
What are endogenous cannabinoid peptides?
They are naturally occurring peptides in the brain that interact with cannabinoid receptors, distinct from the lipid endocannabinoids (anandamide and 2-AG) that are more widely known.
Why is lower GI potency a good thing?
Cannabinoid drugs often cause constipation. If cannabinoid peptides can relieve pain at doses that do not significantly slow the gut, they could offer a better side-effect profile than current cannabinoid analgesics.
Read More on RethinkTHC
- THC-amygdala-anxiety-brain
- anandamide-weed-withdrawal
- cannabinoid-receptors-recovery-time
- cannabis-developing-brain-teenagers
- cant-enjoy-anything-without-weed
- dopamine-recovery-after-quitting-weed
- endocannabinoid-system-explained-simply
- endocannabinoid-system-withdrawal
- nervous-system-weed-withdrawal-fight-flight
- teen-weed-use-under-18-effects-brain
- thc-brain-withdrawal
- thc-prefrontal-cortex-brain-effects
- weed-cortisol-stress-hormones
- weed-memory-loss-recovery
- weed-motivation-amotivational-syndrome
- weed-nervous-system-effects
- weed-reward-system-brain
Cite This Study
https://rethinkthc.com/research/RTHC-01209APA
Li, X-H; Lin, M-L; Wang, Z-L; Wang, P; Tang, H-H; Lin, Y-Y; Li, N; Fang, Q; Wang, R. (2016). Central administrations of hemopressin and related peptides inhibit gastrointestinal motility in mice.. Neurogastroenterology and motility, 28(6), 891-9. https://doi.org/10.1111/nmo.12789
MLA
Li, X-H, et al. "Central administrations of hemopressin and related peptides inhibit gastrointestinal motility in mice.." Neurogastroenterology and motility, 2016. https://doi.org/10.1111/nmo.12789
RethinkTHC
RethinkTHC Research Database. "Central administrations of hemopressin and related peptides ..." RTHC-01209. Retrieved from https://rethinkthc.com/research/li-2016-central-administrations-of-hemopressin
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 RethinkTHC 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.