A Low-Molecular-Weight BDNF Mimetic, Dipeptide GSB-214, Prevents Memory Impairment in Rat Models of Alzheimer’s Disease

Brain-derived neurotrophic factor (BDNF) is known to be involved in the pathogenesis of Alzheimer’s disease (AD). However, the pharmacological use of full-length neurotrophin is limited, because of its macromolecular protein nature. A dimeric dipeptide mimetic of the BDNF loop 1, bis-(N-monosuccinyl-L-methionyl-L-serine) heptamethylene diamide (GSB-214), was designed at the Zakusov Research Institute of Pharmacology. GSB-214 activates TrkB, PI3K/AKT, and PLC-γ1 in vitro. GSB-214 exhibited a neuroprotective activity during middle cerebral artery occlusion in rats when administered intraperitoneally (i.p.) at a dose of 0.1 mg/kg and improved memory in the novel object recognition test (0.1 and 1.0 mg/kg, i.p.). In the present study, we investigated the effects of GSB-214 on memory in the scopolamine- and steptozotocin-induced AD models, with reference to activation of TrkB receptors. AD was modeled in rats using a chronic i.p. scopolamine injection or a single streptozotocin injection into the cerebral ventricles. GSB-214 was administered within 10 days after the exposure to scopolamine at doses of 0.05, 0.1, and 1 mg/kg (i.p.) or within 14 days after the exposure to streptozotocin at a dose of 0.1 mg/kg (i.p.). The effect of the dipeptide was evaluated in the novel object recognition test; K252A, a selective inhibitor of tyrosine kinase receptors, was used to reveal a dependence between the mnemotropic action and Trk receptors. GSB-214 at doses of 0.05 and 0.1 mg/kg statistically significantly prevented scopolamine-induced long-term memory impairment, while not affecting short-term memory. In the streptozotocin-induced model, GSB-214 completely eliminated the impairment of short-term memory. No mnemotropic effect of GSB-214 was registered when Trk receptors were inhibited by K252A.