EVIDENCE FOR MNEMOTROPIC ACTION OF CHOLECYSTOKININ FRAGMENTS BOC-CCK-4 AND CCK-8S

Memory-modulating and reinforcing effects of the cholecystokinin (CCK) fragments, CCK-8S and Boc-CCK-4, after systemic application in rats w ere investigated. Habituation to the novelty of environmental stimuli was used to test for mnemonic effects using two different tasks (reari ng behavior in an open field; head-dips in a hole-board). Immediate po sttrial administration of CCK-8S and Boc-CCK-4 resulted in a reduction of rearing and head-dip behavior during testing, indicative of enhanc ed habituation and, thus, facilitation of memory. In contrast, adminis tration of CCK-8S and Boc-CCK-4 with a delay of 2.5 or 5 h after train ing or pretrial injection of CCK-8S did not enhance habituation. No ev idence for reinforcing or aversive properties of CCK-8S and Boc-CCK-4 was observed in a conditioned place preference task. In summary, the r esults indicate memory-enhancing effects of peripherally, posttrial-ad ministered CCK-8S and Boc-CCK-4.