Effects of opioid agonists and antagonists on oxytocin and vasopressin release in vitro.

Bicknell RJ, Chapman C, Leng G

Neuroendocrinology1 Aug 1985Cited by 58 (Europe PMC)

PMID2864649DOI10.1159/000124168PepBankPUB-02864649

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Summary

The text of this summary is not shown here, because the article license does not allow reuse. Read it at the source (opens in a new tab)

Text rights: Publisher copyright. Results still quote short attributed sentences.

Results from this study7

No result from this study comes from a test of the peptide.

Natural levels measured7

These results measure the body's own peptide. Nobody was given the peptide. They are not evidence about taking it. They are left out of key results, evidence counts and charts.

01LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, the delta-agonist (D-Ala2, D-Leu5)-enkephalin reduced evoked release of the body's own oxytocin by about 25%.
In plain wordsIn lab tests on rat pituitary tissue, a delta-opioid agonist reduced release of the body's own oxytocin by about 25%.
Peptide
Oxytocin
Outcome
DecreaseEvoked oxytocin release with delta-agonist (D-Ala2, D-Leu5)-enkephalin
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Measurements
Reduction of evoked oxytocin release
≈ 25%
delta-agonist (D-Ala2, D-Leu5)-enkephalin
Source sentences
Summary
Oxytocin release was depressed approximately 25% by the delta-agonist (D-Ala2, D-Leu5)-enkephalin but not affected by putative kappa-agonists or by beta-endorphin.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464901
02LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, putative kappa-agonists did not affect evoked release of the body's own oxytocin.
In plain wordsIn lab tests on rat pituitary tissue, putative kappa-opioid agonists did not change release of the body's own oxytocin.
Peptide
Oxytocin
Outcome
No significant changeEvoked oxytocin release with putative kappa-agonists
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Source sentences
Summary
Oxytocin release was depressed approximately 25% by the delta-agonist (D-Ala2, D-Leu5)-enkephalin but not affected by putative kappa-agonists or by beta-endorphin.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464902
03LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, naloxone enhanced evoked release of the body's own oxytocin by up to 90%, with a half-maximal effect at approximately 10(-6) M.
In plain wordsIn lab tests on rat pituitary tissue, naloxone increased release of the body's own oxytocin by up to 90%.
Peptide
Oxytocin
Outcome
IncreaseEvoked oxytocin release with naloxone
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Measurements
Enhancement of oxytocin secretion
≤ 90%
naloxone
Source sentences
Summary
Naloxone, relatively mu-selective, enhanced oxytocin secretion by up to 90% with a half-maximal effect at approximately 10(-6) M.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464903
04LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, the kappa-selective antagonist MR2266 also enhanced release of the body's own oxytocin but showed agonist-like activity at high concentrations.
In plain wordsIn lab tests on rat pituitary tissue, MR2266 increased the body's own oxytocin release but acted like an agonist at high concentrations.
Peptide
Oxytocin
Outcome
IncreaseEvoked oxytocin release with MR2266
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Source sentences
Summary
MR2266, a relatively kappa-selective antagonist also enhanced oxytocin secretion but displayed agonist-like activity at high concentrations.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464904
05LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, the delta-selective antagonist ICI 154129 had no effect on release of the body's own oxytocin.
In plain wordsIn lab tests on rat pituitary tissue, the delta-opioid antagonist ICI 154129 did not change release of the body's own oxytocin.
Peptide
Oxytocin
Outcome
No significant changeEvoked oxytocin release with ICI 154129
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Source sentences
Summary
ICI 154129, a delta-selective antagonist, was without effect on oxytocin secretion.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464905
06LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, opioid antagonists revealed a strong inhibition of the body's own oxytocin secretion by endogenous opioids released during electrical stimulation.
In plain wordsIn lab tests on rat pituitary tissue, the body's own opioids strongly held back the body's own oxytocin release.
Peptide
Oxytocin
Outcome
DecreaseInhibition of oxytocin secretion by endogenous opioids
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Opioid antagonists
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Source sentences
Summary
The use of opioid antagonists revealed a strong inhibition of oxytocin secretion by endogenous opioids released during electrical stimulation.
1 context sentence(design, population, supporting numbers)
Summary · context
We have examined the effects of a range of opioid agonists and antagonists with differing relative selectivities towards opioid receptor subclasses on the secretion of oxytocin and vasopressin from the isolated neurohypophysis. Oxytocin and vasopressin release evoked by brief periods of electrical s…
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464906
07LabEndogenous levelEx vivo tissueMechanism
In isolated rat neurohypophysis, beta-endorphin did not affect evoked release of the body's own oxytocin.
In plain wordsIn lab tests on rat pituitary tissue, beta-endorphin did not change release of the body's own oxytocin.
Peptide
Oxytocin
Outcome
No significant changeEvoked oxytocin release with beta-endorphin
Study
ratn: not reported in source
Isolated neurohypophysis, electrical stimulation
Comparator
Control release without test compound
Outcome group
Receptor activity and mechanism · Endocrine and hormones
Source sentences
Summary
Oxytocin release was depressed approximately 25% by the delta-agonist (D-Ala2, D-Leu5)-enkephalin but not affected by putative kappa-agonists or by beta-endorphin.
This result measures the body's own Oxytocin. Nobody was given the peptide. It is not evidence about taking it.
Report a problemFND-0286464907

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

PepBank keeps every version of the data on this study. Status changes from Retraction Watch, Europe PMC and Crossref are listed with their source.

Version 2Current
11 Oct 2026, 20:03 UTC
Study results updated
Version 1
9 Oct 2026, 02:52 UTC
First added · source update from Europe PMC

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