Medical College of Wisconsin
CTSICores SearchResearch InformaticsREDCap

Selective modulation of excitatory transmission by mu-opioid receptor activation in rat supraoptic neurons. J Neurophysiol 1999 Dec;82(6):3000-5

Date

12/22/1999

Pubmed ID

10601435

DOI

10.1152/jn.1999.82.6.3000

Scopus ID

2-s2.0-0033402110 (requires institutional sign-in at Scopus site)   21 Citations

Abstract

Opioid peptides have profound inhibitory effects on the production of oxytocin and vasopressin, but their direct effects on magnocellular neuroendocrine neurons appear to be relatively weak. We tested whether a presynaptic mechanism is involved in this inhibition. The effects of mu-opioid receptor agonist D-Ala(2), N-CH(3)-Phe(4), Gly(5)-ol-enkephalin (DAGO) on excitatory and inhibitory transmission were studied in supraoptic nucleus (SON) neurons from rat hypothalamic slices using whole cell recording. DAGO reduced the amplitude of evoked glutamatergic excitatory postsynaptic currents (EPSCs) in a dose-dependent manner. In the presence of tetrodotoxin (TTX) to block spike activity, DAGO also reduced the frequency of spontaneous miniature EPSCs without altering their amplitude distribution, rising time, or decaying time constant. The above effects of DAGO were reversed by wash out, or by addition of opioid receptor antagonist naloxone or selective mu-antagonist Cys(2)-Tyr(3)-Orn(5)-Pen(7)-NH(2) (CTOP). In contrast, DAGO had no significant effect on the evoked and spontaneous miniature GABAergic inhibitory postsynaptic currents (IPSCs) in most SON neurons. A direct membrane hyperpolarization of SON neurons was not detected in the presence of DAGO. These results indicate that mu-opioid receptor activation selectively inhibits excitatory activity in SON neurons via a presynaptic mechanism.

Author List

Liu QS, Han S, Jia YS, Ju G

Author

Qing-song Liu PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Animals
Bicuculline
Electrophysiology
Enkephalin, Ala(2)-MePhe(4)-Gly(5)-
Enkephalin, Leucine-2-Alanine
Excitatory Postsynaptic Potentials
GABA Antagonists
In Vitro Techniques
Male
Membrane Potentials
Morphine
Narcotics
Neurosecretory Systems
Patch-Clamp Techniques
Quinoxalines
Rats
Rats, Sprague-Dawley
Receptors, N-Methyl-D-Aspartate
Receptors, Opioid, delta
Receptors, Opioid, mu
Supraoptic Nucleus
Synaptic Transmission