Effect of the Ac-D-MPRG Peptide Based on the C-Terminal Fragment of Arginine-Vasopressin(6–9) on the Behavior of Rats of Different Ages

It was found that Ac-D-MPRG, a tetrapeptide synthesized on the basis of the C-terminal fragment of arginine-vasopressin(6–9), affects anxiety and orienting-exploratory behavior in rats of all three studied age groups upon chronic neonatal administration. It was also found that the peptide has the most pronounced effect under stress conditions. A reduced level of anxiety, which manifested in a decrease in the number of grooming acts in the Elevated Plus Maze test and an increase in the time spent in the light compartment in the Light-Dark Chamber test, was observed in rats treated with the peptide at all three studied doses. Motor activity changed from passive hiding in the prepubertal period to active avoidance in the pubertal period and in adult animals. Based on the obtained data, it can be concluded that the peptide exhibits its effect only in the presence of biologically significant stimuli.