Specific 125I-endothelin-1 binding sites in the central nervous system.

The quantitative receptor autoradiographic method we used revealed that specific 125I-endothelin-1 (125I-ET-1) binding sites are highly concentrated in the choroid plexus (ChP), subfornical organ (SFO), lacunosum molecular layer of the hippocampus (LMol) and granular layer of the cerebellum (GC) of the rat brain. High densities of the binding sites were also observed in the laminae I-III and intermediolateral nucleus of the porcine spinal cord. 125I-ET-1 bound to the rat ChP and LMol with a high-affinity and to the SFO and GC with a low-affinity. The possibility that ET-1 acts as a neuropeptide within the central nervous system by interacting with specific receptors would have to be considered.