Hydrogen sulfide ameliorates learning memory impairment in APP/PS1 transgenic mice: A novel mechanism mediated by the activation of Nrf2.

Beta-amyloid (Aβ) plaques and oxidative stress are associated with the pathogenesis of Alzheimer's disease (AD). Hydrogen sulfide (HS) has been recognized as a cytoprotectant, which improves learning memory impairment and exerts antioxidant effects in neurodegenerative disorders, including AD. The experiment was projected to explore the effects of HS on cognitive deficits, Aβ levels and possible antioxidant mechanisms. Here, APP/PS1 transgenic mice were injected sodium hydrosulfide (NaHS, a HS donor, 2.8mg/kg) once a day for three months. It was found that APP/PS1 transgenic mice exhibited cognitive deficits and a large number of senile plaques, along with neurons decrease and Aβ increase. However, intraperitoneal (i.p.) injection of NaHS improved learning memory deficits, decreased the number of senile plaques, Aβ and Aβ levels, suppressed neurons loss, together with up-regulated the levels of cystathionine-β-synthase (CBS) and 3-mercaptopyruvate-sulfurtransferase (3MST). Furthermore, the protein levels of beta-amyloid precursor (APP) and beta-secretase 1 (BACE1) were dramatically restrained after administration of HS. In addition, HS exerted antioxidant effects via up-regulation nuclear factor erythroid-2-related factor 2 (Nrf2), heme oxygenase-1(HO-1) and glutathione S-transferase (GST). Taken together, these findings suggest that HS ameliorates learning memory impairment, decreases the number of senile plaques in APP/PS1 mice possibly through inhibition of Aβ production and activation of Nrf2/antioxidant response element (ARE) pathway.