Targeting BACE1-mediated production of amyloid beta improves hippocampal synaptic function in an experimental model of ischemic stroke

Post-stroke cognitive impairment and dementia (PSCID) affects many survivors of large vessel cerebral ischemia. The molecular pathways underlying PSCID are poorly defined but may overlap with neurodegenerative pathophysiology. Specifically, synaptic dysfunction after stroke may be directly mediated by alterations in the levels of amyloid beta (A beta), the peptide that accumulates in the brains of Alzheimer's disease (AD) patients. In this study, we use the transient middle cerebral artery occlusion (MCAo) model in young adult mice to evaluate if a large vessel stroke increases brain soluble A beta levels. We show that soluble A beta 40 and A beta 42 levels are increased in the ipsilateral hippocampus in MCAo mice 7 days after the injury. We also analyze the level and activity of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), an enzyme that generates A beta in the brain, and observe that BACE1 activity is increased in the ipsilateral hippocampus of the MCAo mice. Finally, we highlight that treatment of MCAo mice with a BACE1 inhibitor during the recovery period rescues stroke-induced deficits in hippocampal synaptic plasticity. These findings support a molecular pathway linking ischemia to alterations in BACE1-mediated production of A beta, and encourage future studies that evaluate whether targeting BACE1 activity improves the cognitive deficits seen with PSCID.

Automated summary

Post-stroke cognitive impairment and dementia (PSCID) affects survivors of large vessel cerebral ischemia. The molecular pathways underlying PSCID may overlap with neurodegenerative pathophysiology, specifically involving alterations in amyloid beta (A beta) levels. Using a mouse model, this study shows that soluble A beta levels are significantly increased in the hippocampus after a stroke, along with increased activity of BACE1, an enzyme involved in A beta production. Additionally, treatment with a BACE1 inhibitor improves stroke-induced deficits in synaptic plasticity, suggesting a potential therapeutic target for PSCID.