Effect of cimetidine on the density of adrenergic alpha-1 and alpha-2 receptors in the rat whole prostate.

In order to study the antiprostatic effect of cimetidine, we measured adrenergic alpha-1 and alpha-2 receptors of the whole prostate of cimetidine-administered rats using radioligand binding techniques. Saturation experiments using 3H-prazosin and 3H-yohimbine revealed that there were significant amounts of alpha-1 and alpha-2 receptors in the rat whole prostate. There were more alpha-1 receptors than alpha-2 receptors in both the control and treated groups. In the treated group, the density of alpha-1 receptors showed little change, while that of alpha-2 receptors showed a significant decrease in comparison to the control group without changes in KD values. These data suggest that cimetidine affects the prostatic alpha receptors and consequently decreases the density of adrenergic alpha-2 receptors in the prostate.