[Experimental study of antidepressant effects of GB-115 dipeptide]

It was previously reported that GB-115 [Ph(CH2)5CO-Gly-D-Trp-NH2], a tryptophan-containing dipeptide analog of endogenous CCK4, exhibited pronounced anxiolytic effects in behavioral models of anxiety targeted on the "passive" phenotype of the emotional stress reaction. The aim of the present work was to study the modulator action of GB-115 (0.0125-0.1 mg/kg, i.p.) on emotional processes in both mongrel and inbred (BALB/c and C57B1/6) mice with opposite emotionality in Porsolt's test. GB-115 injected at a dose of 0.025 mg/kg led to a decrease in the immobilization time in all animals tested. The effect observed was less potent than that of amitriptyline (10 mg/kg). In contrast to the case of BALB/c mice, GB-115 increased the latent period in both C57B1/6 mice with active type of behavior and in mongrel mice. There were no changes in spontaneous locomotor activity after the acute administration of GB-115 in inbred and mongrel mice. It was found that GB-115 at an anxiolytic dose produced antidepressant-like effects independently of the genetically controlled emotional stress reaction phenotype. These results indicate that the novel dipeptide analog of CCK4 may have potential in the clinical management of concurrent anxiety and depression.