Beta-endorphin, leu-enkephalin, and dynorphin all inhibited TRH release from rat stomach tissue in a dose-dependent, naloxone-reversible manner — matching the cecum findings.
GI tract-wide effectOpioid-TRH suppression confirmed in both stomach and cecum
What the researchers found
Three opioid peptides from different families all inhibited TRH release from rat stomach in a dose-dependent manner, reversible by naloxone.
Why it matters
This confirms that opioid regulation of gut TRH is not limited to one part of the digestive tract. The stomach also responds to opioid peptides by reducing hormone release.
How the study worked
Rat stomach tissue was incubated with opioid peptides and naloxone. TRH released into the medium was measured by radioimmunoassay.
What this study cannot tell us
In-vitro study using isolated stomach tissue. Whether this regulation matters in living animals and what functional consequences it has remain unknown.
How to read the evidence
Preliminary in-vitro study confirming cecum findings in a second gut segment.
When this study was published
Published in 1989 — extended the gut opioid-thyroid finding to the stomach.
The bigger picture
The opioid-TRH regulatory system extends throughout the gut, suggesting a widespread gut opioid-thyroid network that may be clinically important.
Questions still open
- Is the opioid-TRH system altered in GI diseases?
- Could this pathway contribute to the metabolic effects of opioid drugs?
Common questions
Why test multiple gut segments?
What does TRH do in the stomach?
Read the original research
Effect of endogenous opioid peptides on TRH release from rat stomach in vitro.
Endocrinologia experimentalis, 23(1), 11-6
Citation
Mitsuma, T; Hirooka, Y; Nakada, K; Nomura, A; Nogimori, T. (1989). Effect of endogenous opioid peptides on TRH release from rat stomach in vitro.. Endocrinologia experimentalis, 23(1), 11-6.