Possible Interaction: Glycine and Morphine

“The abstinence syndrome to morphine , induced by naloxone administration to primed mice, was reduced by single doses of glycine or beta-alanine.”

“These results indicate the elevated D-serine level following the chronic morphine treatment could at least in part be involved in the activation of NMDA receptors via the glycine site.”

“administration of 10 mg/kg morphine increased the glutamate level and decreased GABA and glycine levels in cortex.”

“Electrophoretically administered morphine and codeine, but not meperidine, blocked the inhibitory effect of glycine on spinal neurones, without reducing the effectiveness of GABA.”

“Within the same sites, morphine increased the synthesis of glycine.”

“ Glycine inhibited the development of postsynaptic dopamine receptor supersensitivity induced by repeated administration of morphine.”

“… morphine … glycine , D(−)‐2‐amino‐5‐phosphonovaleric acid (D‐AP5, an N‐methyl‐D‐aspartate (NMDA) receptor antagonist), γ‐D‐glutamylaminomethyl sulphonic acid (GAMS, a non‐… soluble guanylate cyclase inhibitor), but were not affected by muscimol (a γ‐aminobutyric acidA (GABAA) receptor agonist) and baclofen (a GABAB receptor agonist).”

“The analgesic effect of morphine was antagonized in mice by intracerebroventricular pretreatment with taurine, gamma-aminobutyric acid (GABA) or glycine and was potentiated by ethylene glycol tetra-acetic acid (EGTA) but not altered by L-glutamate or L-aspartate.”

“Our main finding is that the opiate agonists, morphine and levorphanol (5-100 microM), consistently depressed the responses evoked by the putative inhibitory amino acid neurotransmitters glycine and beta-alanine but not GABA.”

“Only morphine specifically reduced the depressant effect of glycine without affecting that of γ-aminobutyric acid.”