Identification and Molecular Characterization of Galanin Receptor Sites in Rat Brain

Receptors for galanin are identified and characterized in rat brain membranes. Interaction of [125I]-galanin with its receptors is saturable, time, pH, and ionic strength-dependent. It is reversible and highly peptide specific. Scatchard analysis of binding data reveals the existence of one single class of high affinity binding sites with a KD of 0.9 nM and a capacity of 101 fmoles/mg membranes protein. Chemical cross-linking of [125I]-galanin to its brain receptor followed by SDS-PAGE analysis leads to the identification of one major protein of 56 kD corresponding to the galanin-receptor complex. Our findings provide the first biochemical characterization of galanin receptors in the central nervous system supporting a role for galanin in the control of brain functions.