Hydrogen sulfide down-regulates BACE1 and PS1 via activating PI3K/Akt pathway in the brain of APP/PS1 transgenic mouse

Background: Endogenous hydrogen sulfide (H2S) may have multiple physiological functions in brain. Our previous study showed that H2S improved spatial memory impairment and decreased the production of AP in APP/PS1 transgenic mice. However, many of the underlying mechanisms are not still being elucidated. The aim of the present study is to investigate the neuroprotective mechanisms of H2S involving in the activity of beta-secretase (BACE1), gamma-secretase (PSI) and alpha-secretase (ADAM17). Methods: Morris water maze was used to measure the behavior change. The levels of A beta 40 and A beta 42 were quantified using colorimetric ELISA kits and immunohistochemical analysis. The levels of BACE1, PSI, ADAM17, pAkt, pp38MAPK, pERK and pJNK were tested by Western blot analysis in normal mice, APP/PS1 transgenic mice and 50 mu mol/kg-NaHS-treated transgenic mice. On the basis of exogenous H2S treatment, LY294002 (inhibitors of PI3K/Akt) or PD98059 (inhibitors of MAPK/ERK) was injected into lateral cerebral ventricle. Results: The levels of BACE1, PS1 and pp38MAPK were increased and ADAM17 were decreased in the APP/PS1 transgenic mice. After intraperitoneal administration of an H2S donor (NaHS) into APP/PS1 mice, the levels of BACE1, PS1 and pp38MAPK were reduced and ADAM17 increased. The level of pp38 MAPKs, pAkt and pERK1/2 was increased in APP/PS1 transgenic mice compared with normal mice (p < 0.05). There was no difference in the expression of pJNK between AD transgenic mice and normal mice (p > 0.05). These results demonstrated that LY294002 inhibited the effect of H2S on decreasing the BACE1 and PS1, reducing the level of A beta and improving memory impairment in APP/PS1 transgenic mice. PD98059 had no influence on the expression of BACE1 and PSI. Conclusions: H2S inhibits the expression of BACE1 and PS1 by activating PI3K/Akt pathway in AD. (C) 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. z o.o. All rights reserved.