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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
6
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pubmed:dateCreated |
1990-8-8
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pubmed:abstractText |
We have localized and characterized the binding of the melatonin agonist, 2-[125I]iodomelatonin, in the rat area postrema (AP), by using quantitative autoradiography in vitro. At equilibrium conditions, Scatchard analysis revealed saturable high-affinity binding to a single class of sites (Kd 45.9 +/- (SE) 6.0 pM and Bmax 30.8 +/- 4.6 fmol/mg protein, n = 4 experiments with a total of 18 rats). Melatonin and 6-hydroxymelatonin were potent displacers of 2-[125I]iodomelatonin binding in the AP (IC50 20 and 500 pM, respectively) while N-acetylserotonin exhibited only a modest potency (IC50 25 nM). Micromolar concentrations of guanine nucleotides dose-dependently and specifically inhibited agonist binding at 22 degrees C. Saturation studies revealed that this was due to a decrease in binding affinity. Divalent cations (4 mM CaCl2 or 2 mM MgCl2) had no detectable effect on the affinity of the binding site, whereas physiological concentrations of NaCl significantly decreased the binding affinity. These results demonstrate specific high-affinity binding sites for 2-[125I]iodomelatonin in the rat AP and suggest coupling of these putative receptors to guanosine nucleotide binding regulatory protein(s).
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/2-iodomelatonin,
http://linkedlifedata.com/resource/pubmed/chemical/6-hydroxymelatonin,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium Chloride,
http://linkedlifedata.com/resource/pubmed/chemical/Cations, Divalent,
http://linkedlifedata.com/resource/pubmed/chemical/GTP-Binding Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Guanine Nucleotides,
http://linkedlifedata.com/resource/pubmed/chemical/Guanosine 5'-O-(3-Thiotriphosphate),
http://linkedlifedata.com/resource/pubmed/chemical/Guanosine Triphosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Magnesium Chloride,
http://linkedlifedata.com/resource/pubmed/chemical/Melatonin,
http://linkedlifedata.com/resource/pubmed/chemical/N-acetylserotonin,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Melatonin,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Neurotransmitter,
http://linkedlifedata.com/resource/pubmed/chemical/Serotonin,
http://linkedlifedata.com/resource/pubmed/chemical/Thionucleotides
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pubmed:status |
MEDLINE
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pubmed:month |
Jun
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pubmed:issn |
0028-3835
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
51
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
619-24
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:2163495-Animals,
pubmed-meshheading:2163495-Autoradiography,
pubmed-meshheading:2163495-Binding, Competitive,
pubmed-meshheading:2163495-Binding Sites,
pubmed-meshheading:2163495-Calcium Chloride,
pubmed-meshheading:2163495-Cations, Divalent,
pubmed-meshheading:2163495-Cerebral Ventricles,
pubmed-meshheading:2163495-GTP-Binding Proteins,
pubmed-meshheading:2163495-Guanine Nucleotides,
pubmed-meshheading:2163495-Guanosine 5'-O-(3-Thiotriphosphate),
pubmed-meshheading:2163495-Guanosine Triphosphate,
pubmed-meshheading:2163495-Magnesium Chloride,
pubmed-meshheading:2163495-Male,
pubmed-meshheading:2163495-Melatonin,
pubmed-meshheading:2163495-Rats,
pubmed-meshheading:2163495-Rats, Inbred Strains,
pubmed-meshheading:2163495-Receptors, Melatonin,
pubmed-meshheading:2163495-Receptors, Neurotransmitter,
pubmed-meshheading:2163495-Serotonin,
pubmed-meshheading:2163495-Thionucleotides
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pubmed:year |
1990
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pubmed:articleTitle |
Characterization of melatonin receptors in the rat area postrema: modulation of affinity with cations and guanine nucleotides.
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pubmed:affiliation |
Section on Pharmacology, National Institute of Mental Health, Bethesda, Md.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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