γ-Hydroxybutyrate (Xyrem) ameliorates clinical symptoms and neuropathology in a mouse model of Alzheimer's disease

Abstract

The chronic decrease of brain amyloid-β (Aβ) peptides is an emerging therapeutic for Alzheimer's disease, but no such treatment has achieved clinical validation yet. In vivo, some brain proteases, including neprilysin, possess the ability of degrading Aβ and experimental data suggest their exploitation in strategies to reduce cerebral Aβ concentration. Previous studies have shown that pharmacologic doses of gamma-hydroxybutyrate (sodium oxybate or Xyrem) induce histone deacetylases (HDACs) inhibition and neprilysin gene expression. Here, we demonstrate that brain neprilysin overexpression induced in vivo by repeated gamma-hydroxybutyrate autoadministration reduces cerebral Aβ contents and prevents cognitive deficits in APPSWE mice. Oral gamma-hydroxybutyrate also counteracted phosphoramidon-induced brain neprilysin inhibition and Aβ accumulation. HDACs activities in SH-SY5Y cells were inhibited by gamma-hydroxybutyrate which did not affect amyloid peptide precursor intracellular domain. Together, our results suggest that gamma-hydroxybutyrate, acting via HDAC inhibition, upregulates neprilysin to reduce Aβ level and related memory deficits. Because gamma-hydroxybutyrate doses used herein are clinically relevant, our data suggest that chronic oral administration of gamma-hydroxybutyrate or its analogs may be considered for strategies against presymptomatic or established Alzheimer's disease.