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Benzodiazepine Binding to Cultured Human Pituitary Cells
Author(s) -
Voigt Mark M.,
Davis Leonard G.,
Wyche James H.
Publication year - 1984
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.1471-4159.1984.tb12850.x
Subject(s) - diazepam , clonazepam , chemistry , benzodiazepine , receptor , flunitrazepam , membrane , incubation , cell , cell membrane , pharmacology , cell culture , gabaa receptor , endocrinology , biochemistry , biology , genetics
Benzodiazepine receptors were investigated in a cell line of human pituitary cells (18‐54,SF) grown in serum‐free medium. Preparations of 18–54,SF whole cells and cell membranes were shown to possess satu‐rable [ 3 H]diazepam binding sites. Membrane sites were found to have a K D of 20 n M for diazepam while whole cells possessed a twofold higher value. The K D values determined from Rosenthal, Hill, and kinetic analyses were consistent for each preparation. Whole‐cell binding of [ 3 H]diazepam was observed to be more stable than binding to membranes at higher temperatures (37°C) and when longer incubation times (60 min) were employed at 4°C. The rank order potency of various benzodiazepines to inhibit [ 3 H]diazepam binding to whole cells and membranes was Ro 5–4864, flunitrazepam, diazepam, and clonazepam. Representatives of other drug classes did not inhibit this benzodiazepine binding. When 18–54,SF cells were grown for 24 h with 100 nM diazepam and then extensively washed membranes prepared, the K D for diazepam increased to 38 n M whereas the B max was unchanged when compared with untreated controls. Overall, these findings indicate that pituitary cells possess a peripheral‐type benzodiazepine receptor and that the whole cell receptor differs quantitatively when compared with the membrane receptor.