NC-1900, a [pGlu4,Cyt6]AVP(4-9) analogue, facilitates the learning performance of rats on delayed nonmatching to sample task in Y-water maze

The effect of a novel peptide, NC-1900 (pGlu-Asn-Ser-Pro-Arg-Gly-NH2) on learning behavior in normal animals was studied in delayed nonmatching to sample tasks in rats using a Y-water maze. In the acquisition tests, a nonmatching to sample task, a delayed nonmatching to sample task with a delay time of 10 min (10-min DNMTS task), and a 20-min DNMTS task were performed for 15 sessions. NC-1900 was administered subcutaneously 1 h prior to the start of the acquisition test once a day. In the retention tests, the 10-min DNMTS task (on days 3, 10 and 17) and 20-min DNMTS task (on days 4, 11, 19 and 26) were conducted over time in the absence of administration of NC-1900 following completion of the acquisition test of the 10-min DNMTS task. In the acquisition of the 10- and 20-min DNMTS tasks, the NC-1900 100 pg/kg group exhibited significantly higher correct choice percentages or percentages of rats that achieved the criteria (mean correct choice percentage for 3 days of 90% or higher) in comparison with the control group. In the retention tests, in contrast to the correct choice percentages on each test day for the 20-min DNMTS task of the control group being approximately 50%, rats administered NC-1900 demonstrated high correct choice percentages at all dose levels, although there were some variations on each test day. These results demonstrate that NC-1900 clearly facilitated acquisition and retention of DNMTS tasks in rats using a Y-water maze.