We studied the anti-anxiety effect of a low-molecular-weight mimetic of the BDNF loop 2, hexamethylenediamide bis-(-N-hexanoyl-L-seryl-L-lysine) (GTS-201) in adult animals. GTS-201 at a dose of 5 mg/kg after acute intraperitoneal administration to outbred male and female rats increased the time spent in the open arms and the number of entries into the open arms in the elevated plus maze (EPM). In "highly emotional" male BALB/c mice, GTS-201 exhibited a dose-dependent anxiolytic effect in the EPM in a dose range of 0.5-2.0 mg/kg with a maximum effective dose of 1 mg/kg. These data confirm the previously revealed anti-anxiety properties of GTS-201 in inbred male and female BALB/c mice and rats and indicate the dependence of the pharmacological activity of the BDNF mimetic on animal age.