Improvements in the selective perception and training of rats using an original analog of the C-terminal fragment of vasopressin.

This report presents studies on the effects of intranasal administration of five doses (0.001, 0.01, 0.1, 1, and 10 microg/kg) of a new analog of arginine-vasopressin fragment AVP(6-9), i.e., D-MPRG, on the learning ability of rats with positive and negative reinforcement. All doses of the peptide improved learning. The most effective dose was 0.01 microg/kg, at which the peptide accelerated the acquisition of a conditioned active avoidance reflex both when given 1 h before and when given immediately after training sessions. The peptide had greater effects when animals were trained with negative reinforcement. Analysis of the results suggests that the action of D-MPRG is mainly on perception processes, i.e., extraction of the conditioned stimulus from the environmental surroundings and evaluation and enhancement of its biological significance. In addition, this peptide prevented extinction of the acquired habit and improved the processes of consolidation, though this effect was weaker than its effect on perception.

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.

[The effect of an original analog of the C-terminal fragment of vasopressin on the behavior of white rats]. / Vliianie original'nogo analoga C-kontsevogo fragmenta vazopressina na povedenie belykh krys.

The influence was studied of a new analog of C-terminal fragment of argininvasopressin Ac-D-MPRG on locomotor and exploratory activity of rats. The peptide injected intranasally in the doses of 0.001, 0.01, 0.1, 1, and 10 mcg/kg one hour prior to testing did not affect the horizontal motor activity of the animals in the "open field" (with red light and white noise) and "Opto-Varimex" tests. It increased the vertical motor activity and decreased grooming in the "open field" and "hole board" tests. The results obtained demonstrate that the analog of AVP (6-9) fragment (with Cys6 changed for D-Met), as well as AVP, increases the exploratory activity. However, in contrast to the whole precursor molecule, the peptide does not change the level of nonspecific motor activity.

[Improvement of the selective perception and learning with the analog of C-terminal fragment of vasopressin in rats]. / Uluchshenie selektivnogo vospriiatiia i obucheniia krys original'nym analogom C-kontsevogo fragmenta vazopressina.

New analogue of the AVP(6-9), the D-MPRG was administered intranasally in different doses. The administration improved the process of conditioning. The most efficient dose turned out to be 0/01 mcg/kg. Tetrapeptide administered 1 hour before each learning session and immediately after it accelerated the avoidance conditioning. The peptide effect was more obvious in conditioning with a negative reinforcement. The data obtained suggest that the D-MPRG mostly affects the perception of experimental environment as well as improves the consolidation of memory traces. The peptide was also shown to delay extinction of previously learned skills.