Dopamine receptors in rabbit and rat eye: characterization and localization of DA1 and DA2 binding sites

In vitro autoradiography is used to characterize and localize DA1 and DA2 receptors in rabbit and rat eyes. The bindings of 125I-SCH 23982 (DA1 antagonist) and of 125I-Iodosulpride (DA2 antagonist) to slide mounted tissue sections take place with characteristics expected of substances that recognize DA1 and DA2 receptors respectively. They are saturable, have high affinity and exhibit an appropriate pharmacology. The regional distribution of these receptors indicates that they are mainly present in retina. Precise cellular localizations are visualized in retinal structures by means of histoautoradiography: DA1 receptors are found in inner plexiform layer, outer plexiform layer and inner nuclear layer and DA2 binding sites are present in the two plexiform layers.