FACILITATION AND ATTENUATION OF SOCIAL RECOGNITION IN RATS BY DIFFERENT OXYTOCIN-RELATED PEPTIDES

The memory-modulating effects of subcutaneously administered oxytocin and related peptides were investigated in the social recognition parad igm in rats. The attenuation of social recognition by 0.6 and 6 mu g/k g of oxytocin was mimicked by the same doses of des-Gly(8)-oxytocin, [ pGlu(4),Cyt(6)]oxytocin-(4-9) and prolyl-leucyl-glycinamide (PLG) and by 0.6 mu g/kg of oxytocin-(1-6) and [pGlu(4),Cyt(6)]oxytocin-(4-8). T he peptide leucyl-glycinamide (LG) was not active in this respect. The facilitation of social recognition by 0.6 and 6 ng/kg of oxytocin was mimicked by the same doses of PLG and LG but not by the other peptide s and the amino acid glycine. It is concluded that the active moieties for attenuation and facilitation of social memory reside in different parts of the oxytocin molecule, e.g. the 5-7 and 8-9 region, respecti vely.