A mimetic of the BDNF loop 4, bis (N-monosuccinyl-L-seryl-L-lysine) hexamethylenediamide, named GSB-106, was designed and synthesized in our scientific group. The compound activated TrkB, MAPK/ERK, PI3K/AKT, and PLCγ in in vitro experiments. In vivo experiments with rodents revealed its antidepressant-like activity in the forced swim and the tail suspension tests at the dose range of 0.1–5.0 mg/kg (i.p., p.o.). However, GSB-106 was not studied in depression models modulating major depression in humans. In the present study, the GSB-106 antidepressant-like activity was revealed in mice at the depression model induced by 28-day social defeat stress with 21-days oral administration (0.1 mg/kg) after stress. At the same time, GSB-106 restored reduced locomotor activity and completely eliminated the anhedonia manifestations. The compound also restored reduced levels of synaptophysin and CREB in the hippocampus. In addition, the Trk receptor antagonist K252A, and the PLC inhibitor U73122, were found to completely block the antidepressant-like activity of GSB-106 in the forced swimming test in mice. Thus, the present results demonstrate the dipeptide BDNF mimetic GSB-106 reversed depressive-like behavior and restored hippocampal neuroplasticity in a rodent depression model. These effects of GSB-106 are probably regulated by TrkB signaling.
We studied the effects of SNK-411, a new 5-pyrimidinol derivative, on serum cytokine profile of C57Bl/6 mice with Lewis lung carcinoma. The compound was injected intraperitoneally in doses of 25 and 50 mg/kg. A significant (by 3.5 times) increase in serum IL-4 content was detected in mice with tumors on day 9 of tumor development. In mice receiving SNK-411 in doses of 25 and 50 mg/kg, IL-4 content significantly decreased (by 4.0 and 3.6 times) on days 2-8 of carcinoma development; IL-2 content decreased by 1.4 and 1.2 times and IL-6 content decreased by 2.7 and 1.6 times, respectively, in comparison with control mice with tumors. Injections of SNK-411 in the same doses on days 8-15 of carcinoma development led to a significant decrease in IL-4 levels (by 2.2 and 4.5 times, respectively, in comparison with control mice with tumors) and did not affect serum levels of other cytokines.