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1. The presynaptic depressant action of L-2-amino-4-phosphonobutyrate (L-AP4) on the monosynaptic excitation of neonatal rat motoneurones has been differentiated from the similar effects produced by (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate ((1S,3R)-ACPD), (1S,3S)-ACPD and (2S,3S,4S)-alpha-(carboxycyclopropyl)glycine (L-CCG-I), and from the postsynaptic(More)
Properties of a new potent antagonist acting selectively at N-methyl-D-aspartate (NMDA) type excitatory amino acid receptors are described. This compound, 3-((+/-)-2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) is more potent than all previously reported NMDA antagonists in depressing mammalian spinal neuronal responses (cat and immature rat), in(More)
Two phenylglycine derivates, (S)-4-carboxyphenylglycine and (RS)-alpha-methyl-4-carboxyphenylglycine, competitively antagonised (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate (ACPD)-stimulated phosphoinositide hydrolysis in rat cerebral cortical slices. The same phenylglycine derivatives selectively antagonized ACPD-induced depolarization in neonatal rat(More)
1) The KD values for a range of antagonists including DGG, pCB-PzDA, pBB-PzDA, HDC-QXCA, DNQX and CNQX have been determined using a series of non-NMDA receptor agonists in the isolated spinal cord of the neonatal rat. 2) CNQX and DNQX, and, to a lesser extent, DCH-QXCA, were by far the most potent antagonists, although the degree of selectivity did not vary(More)
The (+)-enantiomer of alpha-methyl-4-carboxyphenylglycine (MCPG) stereoslectively antagonized the depolarization of neonatal rat motoneurones and the excitation of rat thalamic neurons induced by the specific metabotropic glutamate receptor agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate (ACPD). (+)-MCPG preferentially reduced (1S,3R)-ACPD-induced(More)
The possible roles of G-protein coupled metabotropic glutamate receptors in central nervous function are currently the focus of intensive investigation. The complexity of effects produced by agonists at these receptors probably reflects the activity of a range of sub-types. The metabotropic glutamate receptors first described are linked to phospholipase C,(More)
1. The shift in d.c. potential in dorsal roots (EC50 8.0 microM +/- 0.9 s.e. mean, n = 5) or depression of the C elevation of the compound action potential (EC50 3.0 microM +/- 0.3, n = 7) have been used to measure the depolarizing action of kainate on dorsal root C fibres of immature (3 to 5 day old) rats. Depolarization of motoneurones was measured from(More)
Both the (1S,3S) and (1S,3R) stereoisomers of 1-aminocyclopentane-1,3-dicarboxylate (ACPD), but not the (1R,3R) or (1R,3S) isomers, potently depress the fastest (presumed monosynaptic) component of dorsal root-evoked ventral root potentials in hemisected isolated spinal cord of the newborn rat. This effect is not due to antagonism of known excitatory amino(More)
The potency of 7 excitatory amino acid antagonists had been measured at kainate receptors on primary afferent C fibres using isolated dorsal roots from immature rats. Two of the compounds were tested as antagonists of excitant amino acids at motoneurones using isolated hemisected spinal cord preparations. Mean dose-ratios for antagonism of kainate at C(More)
The depression of monosynaptic excitation of neonatal rat motoneurones by (1S,3S)- and (1S,3R)-1-aminocyclopentane-1,3-dicarboxylate (ACPD) and by L-2-amino-4-phosphonobutyrate (L-AP4), which is probably presynaptically mediated, is antagonized by (+/-)- and (+)-alpha-methyl-4-carboxyphenylglycine (MCPG). The same phenylglycine derivatives also antagonize(More)