Neuroprotective and anti-amnestic effects of a combination therapy in a model of photochemical ischemic damage in the prefrontal cortex

Abstract

The aim of this study was to investigate the effect of combination therapy, including mutant erythropoietin molecules (EPO) and a dipeptide mimetic of the nerve growth factor, GK-2H, on the conditioned passive avoidance (PA) reflex and the volume of injury induced by bilateral ischemia of the prefrontal cortex in rats. Using the method of genetic engineering the mutant molecules of EPO, MERO-TR and MEPO-Fc, with strongly reduced erythropoietic and pronounced cytoprotective activity were created. The used human nerve growth factor mimetic, an endogenous regulatory protein based on the β-bend of loop 4, which is a dimeric substituted dipeptide of bis- (N-monosuccinyl-glycyl-lysine) hexamethylenediamine, GK-2 human (GK-2H), has proven neuroprotective in in vitro experiments. Methods. Bilateral focal ischemic infarction was modeled in the rat prefrontal cortex by photochemically induced thrombosis. The PA test was performed according to a standard method. Volume of brain injury was estimated using MRI. MEPO-TR, and MEPO-Fc (50 µg/kg, intranasally) were administered once, one hour after the injury. GK-2Н (1 mg/kg, i.p.) was injected four hours after the injury and then for next four days. Results. The study showed that the complex therapy provided statistically significant retention of the PA reflex developed prior to ischemia and a significant decrease in the volume of injury. The anti-amnestic and neuroprotective effects of combination therapy were most pronounced at doses of MEPO-Fc 50 μg/kg and GK-2H 1 mg/kg. Conclusion. This study has confirmed the neuroprotective effect and enhancement of the anti-amnestic effect exerted by the combination of mutant erythropoietin derivatives, MEPO-TR and MEPO-Fc, and the dipeptide mimetic of human growth factor GK-2H.