The Influence of the Low-Molecular-Weight NGF Mimetic Dipeptide GK-2 on the Behavior of Mice from Two Outbred Strains That Differ in Brain Weight

This investigation included an analysis of the nootropic effects of a dimeric dipeptide, substance GK-2, a nerve growth factor mimetic, in a cognitive test (object permanence, by J. Piaget) in mice of two strains selected for their large and small relative brain weights (strains LB and SB). The influences of the dipeptide (0.5 mg/kg, injected i.p., subchronically, 5 days) on cognitive test solution in mice of different genotypes were opposite, mice of both strains escaped more quickly in the comfortable dark part of the box, but in cases of the obstacles (the underpass being masked by wood shavings) this effect was significant for 8-month-old LB strain mice, while in SB mice no effect was found. The proportions of mice that solved the task successfully when the underpass was blocked by a plug were lower in LB and higher in SB (the small sizes of groups permitted us to obtain only the tendency in differences from controls). Neophagophobia test performance show that the dipeptide infusion induced more active reaction to the novel food with LB reactions being clearer. The age interstrain differences in solution of this test were also found, both in dipeptide and in the control groups. The data on genotype–dependent changes in behavior after GK-2 infusion are important for more extensive characteristic of GK-2 pharmacological properties as a possible therapeutic drug.