Efects of Newly-synthesized Peptide Mimetics on Exploratory Behaviour, Memory and Serotonin Release in the Hippocampus of Rats with Social Isolation Syndrome

Abstract

The effects of two newly-synthesized peptide mimetics (containing L-valine and nicotinamide/isonicotinamide residues) – M6 and P6 – were studied on Wistar rats after 6 weeks of social isolation. Their influence on changed cognitive functions in experimental aggression in rats was studied with the Hole board test (for exploratory behaviour) and also Step-through test on the 7th and on the 30th day (for short-term and long-term memory). The influence of the compounds on serotonin (5-HT) release in the hippocampus of aggressive rats was also studied, using a scintillation method. It has been found that the new peptide mimetics – M6 and P6, demonstrated different modulating effects on the exploratory behaviour and memory and on the 5-HT release in the hippocampus of grouped and socially-isolated male rats. The two compounds had different effects on the exploratory behaviour and the process of habituation in aggressive animals, probably due to their isomeric structure. M6 increased significantly the memory in grouped animals, but had the opposite effect in aggressive rats. Due to its intrinsic peptidomimetic nature, it is possible that M6 has an affinity towards 5-HT receptors in hippocampus.