[The role of glycine binding site in NMDA receptor--interactions between NMDA and D-serine in artificial anoxia/agycemia rat hippocampus].
BACKGROUND
NMDA receptor contributes to cause neuronal death in anoxic condition. It is not known how a part of NMDA receptors, NMDA-binding site and/or glycine-binding site, influence neuronal damage in rats' hippocampus in vitro.


METHODS
Rats' hippocampus, labeled with norepinephrine (3H-NE), was incubated in artificial cerebrospinal fluid (aCSF) and we measured 3H-NE in superfusion solution and remaining tissue. Glucose was eliminated from aCSF and 95% N2 + 5% CO2 produced the anoxic state.


RESULTS
The amount of 3H-NE release increased in anoxia with NMDA (NMDA-binding site agonist), while there was no influence on NMDA receptor in non-anoxic state even after D-serine (glycine-binding site agonist) has been administered. The 3H-NE was released more when D-serine (100 mu mM) and NMDA (100 mu mM) were administered together than when only D-serine (10 mu mM, 100 mu mM, 1000 mu mM) in anoxia or NMDA (10 mu mM, 100 mu mM, 1000 mu mM) in anoxia was administered.


CONCLUSIONS
Glycine-binding site agonist alone does not act significantly but ion channels in NMDA receptor open more and become more effective when both glycine-binding site agonist and NMDA-binding site agonist exist, suggesting that there are interactions between NMDA-binding site and glycine-binding site in NMDA-receptor during anoxia.
Kawasaki
Kazuyoshi
K
Department of Anesthesiology, Sanraku Hospital, Tokyo 101-8326.
Ogawa
Seturou
S
D000818:Animals; D001665:Binding Sites / Q000187:drug effects / Q000502:physiology*; D005998:Glycine / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D066298:In Vitro Techniques; D016202:N-Methylaspartate / Q000378:metabolism* / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012694:Serine / Q000494:pharmacology*
D016194:Receptors, N-Methyl-D-Aspartate; D012694:Serine; D016202:N-Methylaspartate; D005998:Glycine; D009638:Norepinephrine