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[ 3 H]Propyl β‐Carboline‐3‐Carboxylate Binds Specifically to Brain Benzodiazepine Receptors
Author(s) -
Nielsen Mogens,
Schou Henning,
Braestrup Clam
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb02404.x
Subject(s) - flunitrazepam , gabaa receptor , chemistry , muscimol , binding site , receptor , ligand (biochemistry) , diazepam , cerebellum , benzodiazepine , carboxylate , biochemistry , pharmacology , biology , neuroscience
Ethyl β‐carboline‐3‐carboxylate has recently been isolated from human urine and it was proposed that derivatives of this compound might be related to an endogenous ligand for benzodiazepine receptors. In the present study we investigated high‐affinity binding of [ 3 H]propyl β‐carboline‐3‐carboxylate ([ 3 H]PrCC) to rat brain membranes. [ 3 H]PrCC binds specifically and with high affinity (half‐maximal binding at ca. 1 nM) to rat brain membranes. The regional and subcellular distributions of specific [ 3 H]PrCC binding are similar, but not identical, to the distributions of [ 3 H]flunitrazepam or [ 3 H]‐diazepam binding. The total numbers of binding sites labelled by [ 3 H]PrCC and [ 3 H]flunitrazepam in rat cerebellum are closely similar, and both ligands bind to cerebellar membranes in a mutually exclusive way. The pharmacological selectivity of [ 3 H]PrCC and [ 3 H]diazepam binding is almost identical. Binding of [ 3 H]PrCC, like binding of [ 3 H]diazepam, can be increased in vitro by muscimol, GABA and SQ 20.009. Although subtle differences in binding characteristics were observed, these results indicate that [ 3 H]PrCC and benzodiazepines bind to a common recognition site on benzodiazepine receptors.