Valproic Acid Reduces Neuritic Plaque Formation and Improves Learning Deficits in APPSwe/PS1A246E Transgenic Mice via Preventing the Prenatal Hypoxia-Induced Down-Regulation of Neprilysin

Aims Previously, we have documented that prenatal hypoxia can aggravate the cognitive impairment and Alzheimer's disease (AD) neuropathology in APP(Swe)/PS1(A246E) (APP/PS1) transgenic mice, and valproic acid (VPA) can prevent hypoxia-induced down-regulation of beta-amyloid (A beta) degradation enzyme neprilysin (NEP) in primary neurons. In this study, we have investigated the molecular mechanisms of VPA's anti-AD effects and found that VPA can reduce the prenatal hypoxia-induced neuritic plaque formation and improve the learning deficits in the AD mouse model. Methods The pregnant APP/PS1 transgenic mice were exposed in a hypobaric chamber. Neuritic plaque staining, Morris water maze, and enzyme-linked immunosorbent assay (ELISA) were used to detect the effects of VPA on A beta neuropathology, learning, and memory. Chromatin immunoprecipitation (ChIP) assays and real-time PCR (RT-PCR) were used to determine the effect of VPA on the histone3 acetylation (H3-Ace). Results We found that VPA can inhibit neuritic plaque formation and improve the learning and memory in the prenatal hypoxic APP/PS1 transgenic mice. In addition, VPA treatment can decrease the soluble and insoluble A beta 42 levels and increase the NEP expression via up-regulation of H3-Ace in the APP/PS1 transgenic mice. Conclusion Valproic acid is able to attenuate the prenatal hypoxia-induced A beta neuropathology and learning and memory deficits via inhibiting the activation of histone deacetylase 1 (HDAC1), preventing the decrease in H3-Ace in the NEP promoter regions and reducing the down-regulation of NEP.