MEMORY-ENHANCING EFFECTS OF ARGIPRESSIN A ND ITS RELATIONSHIP WITH PERIAQUEDUCTAL GRAY

Wistar rats were trained to perform shuttle-box active avoidance respo nse. In experiment A, 43 rats were implanted cannulae in bilateral per iaqueductal gray (PAG) and argipressin (Arg) was injected. Arg 0.15 or 0.3 ng but not 0.05 ng retarded the extinction of avoidance response. In experiment B, 37 rats were set up bilateral electrolytic lesions o f PAG or sham lesioned. Arg (6 mu g.kg(-1), ip) was injected after tra ining. FAG lesions blocked the influence of ip Arg on memory enhanceme nt. The results indicated that,Arg may act directly on CNS to modulate d memory and FAG may play an important role in this process. This obse rvation provided further support to the previous suggestion that certa in limbic midbrain structures were involved in memory-enhancement by A rg.