title: [3H]Metergoline: a new ligand of serotonin receptors in the rat brain.
abstract: A specific binding site for [3H]metergoline characterized by a KD of 0.5-1.0 nM was detected in microsomal and synaptic plasma membranes from various areas of the adult rat brain. Experiments with 5,7-dihydroxytryptamine- and kainic acid-induced lesions indicated that this specific binding site was localized post-synaptically with respect to serotoninergic neurons. The pharmacological characteristics of [3H]metergoline binding to microsomal membranes from the whole forebrain strongly suggest that this ligand labels a class of serotonin receptors. This was particularly obvious in the hippocampus in which serotonin was about 400 times more potent than dopamine and noradrenaline for displacing bound [3H]metergoline. In the striatum, serotonin was only 10 times as potent as dopamine in inhibiting [3H]metergoline binding, suggesting that this ligand may also bind to dopamine receptors. Striking similarities between the binding sites for [3H]metergoline and [3H]serotonin were observed in the hippocampus. Thus, not only the total numbers of binding sites for these two ligands in control rats but also their respective increases following intracerebral 5,7-dihydroxytryptamine treatment were very similar. Therefore, at least in the hippocampus, [3H]metergoline might well be the appropriate ligand for studying the characteristics of the 'antagonist form' of serotonin receptors postulated by Bennett and Snyder.
mesh_terms: D015116:5,7-Dihydroxytryptamine / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D004873:Ergolines / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D007608:Kainic Acid / Q000494:pharmacology; D008024:Ligands; D008711:Metergoline / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D009928:Organ Specificity; D051381:Rats; D011985:Receptors, Serotonin / Q000187:drug effects / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013570:Synaptic Membranes / Q000378:metabolism*; D014316:Tritium; D014365:Tryptophan Hydroxylase / Q000378:metabolism
chemical_list: D004873:Ergolines; D008024:Ligands; D011985:Receptors, Serotonin; D014316:Tritium; D008711:Metergoline; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D014365:Tryptophan Hydroxylase; D000262:Adenylyl Cyclases; D007608:Kainic Acid