Ethanol and the peripheral benzodiazepine receptor: in vivo and in vitro experiments.

1. The effect of chronic ethanol exposure on rat peripheral benzodiazepine receptors (PBR) was studied. 2. The binding of 3H-RO 5-4864 to PBR was increased (35.4%) in the kidneys of rats treated with 10% (v/v) ethanol for 12 weeks, but not in renal membranes isolated from rats exposed to ethanol 30% (v/v) during the same period. 3. Similarly, short-term administration of ethanol (4 weeks) did not alter the binding of 3H-RO 5-4864 to renal membranes. 4. To examine the possibility of a direct interaction of ethanol with PBR, in vitro experiments were carried out. Only high concentrations of ethanol (> 100 mM) caused a significant inhibition of 3H-RO 5-4864 binding in kidney, testis and cerebral cortex. 5. The results presented indicate that chronic ethanol exposure causes a time and dose-dependent increase in renal PBR.