SCRATCHING BEHAVIOR INDUCED BY BOMBESIN-RELATED PEPTIDES - COMPARISONOF BOMBESIN, GASTRIN-RELEASING PEPTIDE AND PHYLLOLITORINS

Bombesin and 10 bombesin-related peptides were administered intracereb roventricularly to conscious and freely moving rats. All peptides test ed were found to elicit excessive grooming, especially scratching beha vior. Bombesin itself had the most potent and long-lasting activity in eliciting scratching behavior. Naturally occurring peptides such as n euromedin B and gastrin-releasing peptide (GRP)-(18-27) were short-act ing compared with exogenous peptides such as bombesin and synthesized analogs. Two phyllolitorins, a new bombesin subfamily, were also exami ned in this study. [Leu8]phyllolitorin induced more scratching than [P he8]phyllolitorin and proved to be virtually equipotent to bombesin. C orticotropin-releasing factor (CRF) and substance P induced considerab le excessive grooming, but both peptides were strikingly weak in induc ing scratching behavior. It is suggested that (1) scratching represent s a specific behavior commonly induced by bombesin-related peptides an d (2) the relative potency to induce scratching behavior reflects the metabolic stability of the peptide, e.g. endogenous versus exogenous, shorter versus longer sequences, or chemical protection of N-terminus.