Release-enhancing glycine-dependent presynaptic NMDA receptors exist on noradrenergic terminals of hippocampus.
The release of [3H]noradrenaline ([3H]NA) in superfused rat hippocampal synaptosomes was increased concentration dependently by N-methyl-D-aspartate (NMDA). Glycine (1 microM), ineffective on its own, doubled the efficacy of NMDA with no significant change in affinity. The effects of NMDA alone and those of NMDA + glycine were antagonized by D-2-amino-5-phosphonopentanoate (D-AP5), Mg2+, (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohept-5,10-imine hydrogen maleate (MK-801) or 7-chloro-kynurenate (7-Cl-KYNA) but not by strychnine. The data provide a direct demonstration of the existence of presynaptic NMDA receptors.
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Istituto di Farmacologia e Farmacognosia, Università degli Studi di Genova, Italy.
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D000818:Animals; D004357:Drug Synergism; D005998:Glycine / Q000494:pharmacology*; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000378:metabolism
D016202:N-Methylaspartate; D005998:Glycine; D009638:Norepinephrine