AUTORADIOGRAPHIC EVIDENCE FOR ENDOTHELIN RECEPTORS ON ASTROCYTES IN CULTURES OF RAT CEREBELLUM, BRAIN-STEM AND SPINAL-CORD

The cellular localization of binding sites for I-125-endothelin-1 and -3 (ET-1, ET-3) was studied in explant cultures of rat cerebellum, brain stem and spinal cord by means of autoradiography. The majority of astrocytes in these cultures expressed binding sites for both ET-1 and ET-3. There was a difference in the intensity of labelling between glial cells in the same culture. Some cells revealed intense radioactivity whereas neighbouring astrocytes were only slightly labelled. Besides glial cells, cerebellar neurones, presumably Purkinje cells and granule cells as well as medium-sized and large neurones in brain stem and spinal cord cultures showed binding sites for both peptides. Our results provide strong evidence for the existence of ET receptors on astrocytes.