Objective      To determine the effect of exogenous hydrogen sulfide (H

2

S) on the expression of presenilin 1 (PS1) and β-amyloid (Aβ) in primary cultured neurons.       Methods       Sodium hydrosulfide (NaHS)

as H

2

S donor

  was used to t

reat primary cultured cortical neurons derived from newborn SD rats at a dose of 0

5

10

20

30

40 and 50 μmol/L respectively for 24 h. Cell apoptosis was observed by TUNEL assay. Aβ1-42 level in the supernatant was measured by ELISA. The expression of PS1 protein was determined by Western blotting. The neurons was treated respectively by 0 μmol/L NaHS (control)

20 μmol/L NaHS

20 μmol/L NaHS+20 μmol/L LY294002 (PI3K signal inhibitor)

and 20 μmol/L NaHS+20 μmol/L PD98059B (MAPK signal inhibitor). Western blotting was used to detect the protein level of PS1.       Results      The apoptotic rate had no obvious change when the dose of NaHS was 5

10 and 20 μmol/L

and was significantly increased at the dose of 30-50 μmol/L (

P

0.05). NaHS treatment at 10 and 20 μmol/L resulted in a decrease in Aβ1-42 concentration in the supernatant (

P

0.05) and in the protein level of PS1 (

P

0.05). Compared to the control

the expression of PS1 in the neurons treated by 20 μmol/L NaHS in presence or absence of PD98059B was significantly decreased (

P

0.05)

but had no change in the cells treated in presence of LY294002 (

P

0.05). There was also no difference in the protein level between the cells in presence or absence of PD98059B (

P

0.05). The PS1 protein level was decreased in the cells treated by PD98059B than those by LY294002.       Conclusion      Low-dosed exogenous H

2

S (30 μmol/L NaHS) does not induce obvious apoptosis

and decreases the protein levels of Aβ1-42 and PS1 in primary cultured neurons

which probably through PI3K signal pathway.