Diazepam receptors on mouse astrocytes in primary cultures: displacement by pharmacologically active concentrations of benzodiazepines or barbiturates

Astrocytes in primary cultures were found to bind large amounts of [3H]diazepam. More than 90% of the total binding is specific, i.e., displaceable by an excess of nonlabeled diazepam. At saturation the specific binding amounts to about 20 pmol/mg protein and the Kd value is 30 nM. Clonazepam and flurazepam displace [3H]diazepam from its specific binding sites; 20-30% displacement is brought about by 0.1-0.3 microM clonazepam, which is similar to the plasma concentrations encountered in epileptic patients treated with this drug. Barbiturates have a similar effect, but considerably higher concentrations are required.