The discrete distribution and pharmacological characteristics of melatonin binding sites in the bovine hippocampus were determined. Autoradiography revealed the presence of melatonin binding sites in the stratum lacunosum-molecularis of the hippocampus (CA1), stratum molecularis of the subiculum and in the enthorhinal cortex. Analysis of the kinetic parameters demonstrated that the binding was stable and reversible, represented by a single class high affinity binding sites (Kd 40 pM, Bmax = 3.9 fmol/mg protein). However, 2-iodomelatonin and 2-bromomelatonin inhibited 2-[125I]iodomelatonin binding in a biphasic manner. The presence of 4 mM CaCl2 did not cause changes in the affinity constant values. Finally, experiments performed with GTP gamma S revealed that binding affinity was not decreased even with high concentrations of the nucleotide. These findings show that 2-[125I]iodomelatonin binding sites in the bovine parahippocampal-hippocampal region possess some binding features not common to melatonin receptors described so far; moreover they seem not to be linked to a regulatory G-protein.

2-[125I]iodomelatonin binding sites in the bovine hippocampus are not sensitive to guanine nucleotides / R. Nonno, V. Lucini, B. Stankov, F. Fraschini. - In: NEUROSCIENCE LETTERS. - ISSN 0304-3940. - 194:1-2(1995 Jul 14), pp. 113-116.

2-[125I]iodomelatonin binding sites in the bovine hippocampus are not sensitive to guanine nucleotides

V. Lucini;F. Fraschini
1995-07-14

Abstract

The discrete distribution and pharmacological characteristics of melatonin binding sites in the bovine hippocampus were determined. Autoradiography revealed the presence of melatonin binding sites in the stratum lacunosum-molecularis of the hippocampus (CA1), stratum molecularis of the subiculum and in the enthorhinal cortex. Analysis of the kinetic parameters demonstrated that the binding was stable and reversible, represented by a single class high affinity binding sites (Kd 40 pM, Bmax = 3.9 fmol/mg protein). However, 2-iodomelatonin and 2-bromomelatonin inhibited 2-[125I]iodomelatonin binding in a biphasic manner. The presence of 4 mM CaCl2 did not cause changes in the affinity constant values. Finally, experiments performed with GTP gamma S revealed that binding affinity was not decreased even with high concentrations of the nucleotide. These findings show that 2-[125I]iodomelatonin binding sites in the bovine parahippocampal-hippocampal region possess some binding features not common to melatonin receptors described so far; moreover they seem not to be linked to a regulatory G-protein.
Animals; Cattle; Guanine Nucleotides; Hippocampus; Dose-Response Relationship, Drug; Kinetics; Melatonin; Autoradiography; Male; Female; Binding Sites
Settore BIO/14 - Farmacologia
NEUROSCIENCE LETTERS
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/258165
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