Interaction of strychnine-insensitive glycine binding with MK-801 binding in brain synaptic membranes.
Strychnine-insensitive [3H]glycine binding was detected in brain synaptic membranes treated with Triton X-100 using a filtration assay method. The binding was a time-dependent, inversely temperature-dependent, and reversible process with a relatively high affinity for the neuroactive amino acid. Scatchard analysis revealed that Triton treatment doubled both the affinity and density of the binding sites, which consisted of a single component. The binding was not only displaced by structurally-related amino acid such as D-serine and D-alanine, but also inhibited by some peptides containing glycine, including glycine methylester and N-methylglycine. These ligands invariably potentiated the binding of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]- cyclohepten-5,10-imine ([3H]MK-801), a noncompetitive antagonist for the N-methyl-D-aspartate-sensitive subclass of the central excitatory amino acid receptors, in a concentration-dependent manner. Among various endogenous tryptophan metabolites, kynurenic acid significantly inhibited the strychnine-insensitive [3H]glycine binding. The Triton treatment did not affect the pharmacological profile of [3H]MK-801 binding sites. These results suggest that brain synaptic membranes treated with Triton X-100 are useful in evaluating the strychnine-insensitive and kynurenate-sensitive binding sites of glycine, which are functionally linked to N-methyl-D-aspartate- sensitive receptor channels.
Department of Pharmacology, Setsunan University, Osaka, Japan.
Y
Y
Yoneda
K
K
Ogita
T
T
Suzuki
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001921:Brain / Q000378:metabolism*; D003986:Dibenzocycloheptenes / Q000378:metabolism* / Q000494:pharmacology; D016291:Dizocilpine Maleate; D004347:Drug Interactions; D005998:Glycine / Q000378:metabolism*; D008297:Male; D016202:N-Methylaspartate; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism; D013237:Stereoisomerism; D013331:Strychnine / Q000494:pharmacology*; D013570:Synaptic Membranes / Q000378:metabolism*
D003986:Dibenzocycloheptenes; D001224:Aspartic Acid; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D013331:Strychnine; D005998:Glycine