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Specific binding of L-[3H]-glutamic acid to rat substantia nigra synaptic membranes.
Specific binding of L-[3H]-glutamic acid to rat substantia nigra synaptic membranes.
- Source :
-
Journal of receptor research [J Recept Res] 1986; Vol. 6 (5-6), pp. 339-60. - Publication Year :
- 1986
-
Abstract
- The specific binding of L-[3H]-glutamic acid (GLU) was investigated in synaptic membranes from rat substantia nigra. L-[3H]-GLU binding to the membrane preparations occurred in a reversible and saturable way. The specific binding was stimulated by the presence of CaCl2 and was reduced by freezing and thawing the membranes. Scatchard analysis of the saturation isotherms yielded a non-linear plot suggesting that the binding reaction does not occur through a simple bimolecular association. Assuming non-interacting binding sites, a high (KD1, 139 nM; Bmax1, 3.5 pmoles/mg protein) and a low (KD2, 667 nM; Bmax2, 15.1 pmoles/mg protein) affinity L-[3H]-GLU binding site were obtained. The kinetics of dissociation of bound L-[3H]-GLU was biphasic; the respective dissociation rate constant (k-1) being 0.20 min-1 and 0.013 min-1. A series of amino acid receptor agonists and antagonists were tested as inhibitors of L-[3H]-GLU specific binding. Quisqualic acid, L-GLU and D-alpha-aminoadipate (D-alpha-AA) were the most potent inhibitors. DL-2-amino-4-phosphonobutyrate (APB), N-Methyl-D-aspartate (NMDA) and D-GLU were moderate inhibitors, whereas diaminopimelic acid (DAPA) and glutamate diethyl ester (GDEE) exhibited the lowest relative potency. Kainic acid (KA), gamma-aminobutyric acid (GABA) and bicuculline were not able to modify at any concentration used the specific binding of L-[3H]-GLU. These data demonstrate the presence of specific GLU binding sites in synaptic structures at substantia nigra level and support the idea that excitatory amino acids may play a role in synaptic transmission in this brain region.
- Subjects :
- 2-Aminoadipic Acid pharmacology
Aminobutyrates pharmacology
Animals
Glutamates pharmacology
Glutamic Acid
Humans
In Vitro Techniques
Kinetics
Male
Oxadiazoles pharmacology
Quisqualic Acid
Radioligand Assay
Rats
Rats, Inbred Strains
Receptors, Glutamate
Receptors, Neurotransmitter drug effects
Glutamates metabolism
Receptors, Neurotransmitter metabolism
Substantia Nigra metabolism
Synaptic Membranes metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0197-5110
- Volume :
- 6
- Issue :
- 5-6
- Database :
- MEDLINE
- Journal :
- Journal of receptor research
- Publication Type :
- Academic Journal
- Accession number :
- 2884309
- Full Text :
- https://doi.org/10.3109/10799898609074819