Restoring synaptic plasticity and memory in mouse models of Alzheimer's disease by PKR inhibition

Abstract

Alzheimer's disease (AD) is a neurodegenerative disorder associated with deficits in cognition and synaptic plasticity. While accumulation of amyloid beta (A beta) and hyper-phosphorylation of tau are parts of the etiology, AD can be caused by a large number of different genetic mutations and other unknown factors. Considering such a heterogeneous nature of AD, it would be desirable to develop treatment strategies that can improve memory irrespective of the individual causes. Reducing the phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2 alpha) was shown to enhance long-term memory and synaptic plasticity in naive mice. Moreover, hyper-phosphorylation of eIF2 alpha is observed in the brains of postmortem AD patients. Therefore, regulating eIF2 alpha phosphorylation can be a plausible candidate for restoring memory in AD by targeting memory-enhancing mechanism. In this study, we examined whether PKR inhibition can rescue synaptic and learning deficits in two different AD mouse models; 5XFAD transgenic and A beta(1-42)-injected mice. We found that the acute treatment of PKR inhibitor (PKRi) can restore the deficits in long-term memory and long-term potentiation (LTP) in both mouse models without affecting the A beta load in the hippocampus. Our results prove the principle that targeting memory enhancing mechanisms can be a valid candidate for developing AD treatment.