The effects of a novel analog of the C-terminal fragment of vasopressin on the behavior of white rats.

The effects of an arginine-vasopressin fragment, Ac-D-MPRG, on the movement activity and orientational-investigative activity of white rats were studied. Peptide was given intranasally at doses of 0.001, 0.01, 0.1, 1, and 10 micrograms/kg 1 h before testing. All peptide doses increased vertical movement activity in an open field test and hole board test and decreased grooming levels in both tests. The peptide had no effect on horizontal movement activity. Analysis of these results led to the conclusion that Ac-D-MPRG increases orientational-investigative activity, but, unlike arginine-vasopressin, does not affect non-motivated movement activity.