ro-05-4082 and Neuroblastoma

We have demonstrated high affinity diazepam binding sites of the Ro5-4864 benzodiazepine receptor subtype on 108CC15 neuroblastoma X glioma hybrid cells. These cells were previously shown to have purinoceptors of the A2 adenosine subtype and we have now found that [3H]-adenosine can be displaced from this binding site by the benzodiazepines and related compounds that can also bind to the Ro5-4864 site. Diazepam was found to have no intrinsic activity at the A2-receptor as measured by the stimulation of adenosine 3':5'-cyclic monophosphate (cyclic AMP) production in this cell line. At concentrations sufficient to compete for the A2-receptor, diazepam was shown to facilitate, by approximately 2 fold, the stimulation of cyclic AMP by adenosine. These effects are not due to inhibition of adenosine uptake or phosphodiesterase activity, but are probably a consequence of modulation of the coupling of the A2-receptor to cyclic AMP production in this hybrid cell line.

Topics: Animals; Anti-Anxiety Agents; Benzodiazepines; Binding, Competitive; Cells, Cultured; Clonazepam; Cyclic AMP; Diazepam; Glioma; Hybrid Cells; Kinetics; Neuroblastoma; Phosphodiesterase Inhibitors; Pyrrolidinones; Receptors, Cell Surface; Receptors, GABA-A; Receptors, Purinergic; Rolipram