Quantitative autoradiographic distribution and pharmacological characterization of (3H)buspirone binding to sections from rat, bovine and marmoset brain.

(3H)Buspirone binds with high affinity (KD = 11 nM) to sections from rat striatum. Spiroperidol, chlorpromazine, (+)-butaclamol and apomorphine are the most potent inhibitors of (3H)buspirone binding. Ketanserin, SCH 23390, serotonin and phentolamine are clearly less active. The regional distribution of (3H)buspirone binding in rat and marmoset brain is characterized by high silver grain densities in the olfactory tubercle, nucleus accumbens and striatum. In the hypophysis, the pars intermedia is strongly labeled. Within the hippocampal formation, slightly higher binding site densities are found in the dentate gyrus. The distribution pattern of binding sites in the dentate gyrus varies according to the species investigated. The data presented in this study permit the conclusion that (3H)buspirone binds with high affinity to dopamine 2 receptors but do not exclude additional binding to other types of receptors, e.g. 5-HT1 receptors. The interaction of buspirone with dopamine 2 receptors may be mainly responsible for its pharmacological profile.