Autoradiographic localization of binding sites for 3H-serotonin and 3H-ketanserin on neurones and astrocytes of cultured rat brain stem and spinal cord.

By means of lightmicroscopic autoradiography we have studied the cellular localization of binding sites for 3H-serotonin and 3H-ketanserin in organotypic cultures of rat brain stem and spinal cord. In both types of cultures, a relatively great number of neurones revealed binding sites for 3H-serotonin which predominantly labels S1-receptors. 3H-ketanserin, an S2-antagonist was also bound to many neurones although to a lesser extent than 3H-serotonin. Binding sites for both radio-ligands were also observed on astrocytes. These findings together with electrophysiological investigations indicate that astrocytes possess serotonin receptors.