Postponed effect of cholecystokinin fragments 30-33 (CCK-4), and 31-33 (CCK-3), on albino rats behavior

It is generally accepted that regulatory olygopeptides cause short‐term physiological effects. However we demonstrate that CCK‐4, and its shorter fragment CCK‐3 evoke significant long‐term changes in albino rat behavior. The anxiogenic action of CCK‐4 (400 mg/kg) and CCK‐3 (10 mg/kg) was measured by cross‐maze and dark‐light test. The tendency of rats to developing of depression‐like states was evaluated by the Porsolt‐test. In this study both CCK‐4 and CCK‐3 induced significant behavior effects from 40th min to 12th day after the intraperitoneal administration. It was found also that there were significant changes in the level of bioamines and their derivatives not only during the first hours after the administration but also on the 5th and 12th day. The half‐life of these peptides is less than 15 min, so it's possible the induction of some chain‐reactions similar to memory consolidation process.