Comparative competition binding profiles of BIBP3226 (nonpeptidergic Y1 antagonist), BIBP3435 (S-enantiomer of BIBP3226), GW1229 (peptidergic Y1antagonist), and several pancreatic polypeptides (human, bovine, rat, and avian PP) against [125I][Leu31,Pro34]PYY in rat brain membrane homogenates. Each point represents the mean ± SEM of four to six determinations, each performed in triplicate and expressed as the percentage of specific binding.