Memory enhancement induced in chicks by L-prolyl-L-leucyl-glycinamide.

Two-day-old chicks were injected either intraventricularly or intraperitoneally with saline or a L-prolyl-L-leucyl-glycinamide solution. This C-terminal tripeptide of oxytocin produced retrograde enhancement when injected centrally but not peripherally. Possible memory mechanisms are discussed in light of this peptide's relationship to oxytocin, MSH, and dopaminergic systems.