Non-benzodiazepine, Ag-dependent, brain-specific binding sites for [3H]beta-carboline-3-carboxylic acid ethyl ester.

Specific, saturable and reversible binding of [3H]beta + CCE ([3H]beta-carboline-3-carboxylic acid ethyl ester) in buffer containing 20 microM AgNO3 and 10 microM diazepam was detected in rat brain membranes. The binding of [3H]beta CCE to non-benzodiazepine binding sites is Ag+ (Cu)-dependent, stimulated by NaCl and ascorbic acid and inhibited by dithiothreitol. The concentration of non-benzodiazepine [3H]beta CCE binding sites (Bmax) determined in the brain membranes was 1180 +/- 320 pmol/g tissue, and Kd = 77 +/- 19 nM. [3H]beta CCE bound to benzodiazepine receptors in the same membranes with Bmax = 81 +/- 9 pmol/g tissue and Kd = 3.2 +/- 0.4 nM.