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A novel specific binding site for anxiolytic homophthalazines in the rat brain
Author(s) -
Salamon Cecilia,
Horváth Edit J.,
Fekete Márton I.K.,
Arányi Péter
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81277-s
Subject(s) - radioligand , binding site , chemistry , anxiolytic , striatum , mechanism of action , radioligand assay , biophysics , receptor , pharmacology , biochemistry , in vitro , biology , endocrinology , dopamine
Radioligand binding studies were performed in order to elucidate the mechanism of action of anxiolytic‐neuroleptic homophthalazines. Rat striatal membrane preparations were found to bind 3 H‐EGIS 6775 [ 3 H‐GYKI‐52 322, 3 H‐(I‐(4‐aminophenyl)‐4‐methyl‐7,8‐dimethoxy‐5H‐homophthalazine)] in a specific and displaceable manner. Several other brain regions tested were devoid of similar binding activity. Saturation analysis revealed that binding affinity was in the 10 −5 ‐10 −7 M range. Binding was enhanced by Mg 2+ ions and, to a smaller extent by Ca 2+ ions. The binding principle was sensitive to heat or trypsin treatment. This specific binding site appears, according to competition studies, different from the receptors whose presence in the rat striatum has been reported earlier.