Characterization of peripheral-type benzodiazepine recognition sites in the rat spinal cord

• Published in: Neuropharmacology Vol. 24; no. 2; p. 95
• Main Author: Villiger, J W
• Format: Journal Article
• Language: English
• Published: England 01.01.1985
• Subjects: Animals; Benzodiazepines - metabolism; Benzodiazepinones - metabolism; Binding Sites; Brain - metabolism; Diazepam - metabolism; Flunitrazepam - metabolism; Kinetics; Male; Rats; Rats, Inbred Strains; Spinal Cord - metabolism
• ISSN: 0028-3908
• DOI: 10.1016/0028-3908(85)90166-2

The binding of [3H]Ro 5-4864 to membranes prepared from spinal cord of the adult rat has been studied in vitro. At 4 degrees C, the binding of [3H]Ro 5-4864 reached equilibrium by 120 min, and was rapidly reversible (dissociation t0.5 = 21 min). The [3H]Ro 5-4864 bound with a high affinity (Kd approximately equal to 3 nM) to a single, saturable population of binding sites (Bmax = 27 pmol/g tissue wet weight). Activation of receptors for gamma-aminobutyric acid with 10 microM muscimol did not alter these binding parameters. The drugs Ro 5-4864, diazepam and flunitrazepam were potent inhibitors of this binding (Kis of 10(-9)-10(-8) M) whereas clonazepam, CL 218,872 and Ro 15-1788 were weak inhibitors (Kis greater than 10(-5) M). A comparison of the binding of [3H]Ro 5-4864 in spinal cord with that in other areas of the CNS revealed that whereas the binding affinity was similar in all regions, membranes from spinal cord contained a slightly greater number of binding sites than cerebral cortex and cerebellum, and approximately one-third of the number present in the olfactory bulb. The characteristics of the binding of [3H]Ro 5-4864 obtained in this study are consistent with this ligand binding to peripheral-type benzodiazepine recognition sites in membranes from spinal cord.