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.
|Titolo:||2-[125I]iodomelatonin binding sites in the bovine hippocampus are not sensitive to guanine nucleotides|
|Parole Chiave:||Animals; Cattle; Guanine Nucleotides; Hippocampus; Dose-Response Relationship, Drug; Kinetics; Melatonin; Autoradiography; Male; Female; Binding Sites|
|Settore Scientifico Disciplinare:||Settore BIO/14 - Farmacologia|
|Data di pubblicazione:||14-lug-1995|
|Digital Object Identifier (DOI):||10.1016/0304-3940(95)11742-F|
|Appare nelle tipologie:||01 - Articolo su periodico|