Centrally specific and GABA-insensitive inhibition of benzodiazepine binding by prostaglandins (A1, A2 and B2).

Prostaglandins A1, A2 and B2 (PG A1, A2 and B2) dose-dependently inhibited specific [3H]diazepam binding to rat brain membranes but did not affect specific [3H]Ro 5-4864 binding to kidney membranes. The inhibition of [3H]diazepam binding to brain membranes by benzodiazepine agonists (diazepam and flurazepam) was potentiated by 30 microM GABA, whereas those of prostaglandins were not modified by the same concentration of GABA. These results suggest that PG A1, A2 and B2 specifically interact with central type-benzodiazepine receptors in a manner different from interactions seen with benzodiazepine agonists.