Introduction:
The synthetic heptapeptide (TP-7) consists of a tetrapeptide tuftsin (Thr-Lys-Pro-Arg) and 3 natural L-amino acids Pro-Gly-Pro. The presence of Pro-Gly-Pro group increased the resistance of the synthetic tuftsin derivative to adverse effects of external and internal factors. TP-7 posesses not only anxiolytic, but also other activities. Diazepam (DZ) is a widely used benzodiazepine with anxiolytic, miorelaxant and anticonvulsive activity.

Material and methods:
Rodina’s multiparameter method for complex evaluation of the anxiety-phobic states in rats was used. Experiments were conducted three times as per the following: 24 hours before drug application, 15 minutes before drug application, and 24 hours after its intraperitoneal administration. TP-7 was given at the doses: 0.3 mg/kg and 3 mg/kg. DZ was given at the doses 0.2 mg/kg and 5 mg/kg. The numbers of scores received for each group of animals on the second and on the third day of the experiment were compared with the issue value
accepted as 100% for the first day.

Results:
In the day of application TP-7 (0.3 mg/kg) decreased a fear level about 32 % (no statistical significance), at the dose of 3 mg/kg, TP-7 decreased a fear level about 20 % (p<0.05), In the day of application DZ decreased the animals’ fear level significantly (p<0.05) (the 0.2 mg/kg dose about 33 % and the 5 mg/kg dose about 52 %). 24 hours after its application TP-7 (0.3 mg/kg) decreased a fear level about 39% (p<0.01), and did not influence on
the behavior of rats at the dose of 3 mg/kg. There were no significant changes 24 hours after DZ administration.

Conclusions:
The influence of TP-7 and diazepam on behavior of rats of high emotional reactivity confirms their central anxiolytic activity. TP-7 at the dose 0.3 mg/kg has a prolonged effect than at the dose of 3 mg/kg. The time dependant influence of the examined substances requires further study.