Characterization of Benzodiazepine Binding to GABAA Receptors

Abstract

AbstractThis unit describes ligand binding assays for the characterization of the benzodiazepine (BZ) site of GABAA receptors in the central nervous system. Compounds, such as diazepam, acting at this site are widely used therapeutically as tranquilizers, hypnotics, anticonvulsants, and muscle relaxants. Originally, this site was termed the BZ receptor. However, since it does not characterize a receptor in its own right, but rather a modulatory site of GABAA receptors, the term BZ site is now frequently used. The basic protocol provides a procedure for analyzing benzodiazepine binding to GABAA receptors from brain. The experimental design of the method is suitable for all commercially available radioligands that interact with the BZ site of central GABAA receptors. By using the appropriate radioligand in combination with particular displacer compounds, individual (or groups of) GABAA receptor subtypes can be identified. Preparation of membrane suspensions for this procedure is described in a support protocol, and five alternate protocols are provided for the identification of diazepam‐sensitive GABAA receptors, the a1‐subtype of diazepam‐sensitive receptors, the a5 subtype of diazepam‐sensitive receptors, both diazepam‐sensitive and diazepam‐insensitive receptors, and diazepam‐insensitive receptors exclusively. Each protocol contains a brief description of the requirements for radioligand binding to these five types of BZ sites.