Characterization of specific receptors for vasopressin in the pituitary gland

The present paper reports new findings concerning interaction of [3H]-Arginine-vasopressin with putative receptors in rat anterior pituitary gland. It shows the presence of a single type of receptor sites, with a limited binding capacity and a dissociation constant of nearly 1nM. The parent neurohormone oxytocin revealed weak affinity as compared with vasopressin [Ki = 100nM and Ki = 1nM, respectively]. None of the various peptides tested and, especially corticotropin-releasing factor CRF, competed for binding. Receptor characteristics appeared to be unaffected by lack of circulating vasopressin in Brattleboro rats presenting complete deficiency in synthesis of that peptide.