PC12 cell apoptosis induced by beta-amyloid 25-35 and the protective effect of olanzapine

Zhenfu WANG; Zelan WEI; Xinmin LI; Luning WANG

ABSTRACT

BACKGROUND:

β-amyloid has been proved to be capable of inducing cell apoptosis and play a vital role in Alzheimer disease (AD).

OBJECTIVE:

To probe into olanzapine's protective effect and mechanism of PC12 cell apoptosis induced by β-amyloid 25-35.

SETTING:

Department of Neurology, Southern Building of the General Hospital of Chinese PLA.

DESIGN:

Randomized design.MATERIALS This experiment was carried out in the Neuropsychopathic Research Institute, Medical College of the University of Saskatchewan(Canada), between May 2002 and March 2003.

METHODS:

P12 cells were cultured with RPMI1640 culture medium.100 μL cell suspension was inoculated in each well of 96-well culture plate, and 5 mL suspension was inoculated in 25 cm2 culture bottle covered with collagen and cultured for 24 hours, then with additional 50 μmol/L and 100 μmol/L olanzapine, respectively, for 24 hours, and β-amyloid 25-35 of different concentrations (0.01 μmol/L, 2 μmol/L and 20 μmol/L) for 24 hours. PC12 cell apoptosis was induced by β-amyloid 25-35 in 96-well culture plate and cells were harvested to assay their survival rate with MTF colorimetric assay. PC12 cells in 25-cm2 culture bottles were also harvested to detect the effect of olanzapine on Bax and caspase-3 expression in PC12 cells using Western blot assay.MAIN OUTCOME

MEASURES:

① Cell survival rate; ② the expression of Bax and caspase-3 in PC12 cells.

RESULTS:

① Cell survival rate cell activity was found declined from 75% to 35% in PC12 cells induced by β-amyloid 25-35, but obviously increased in PC12 cells due to pretreatment with olanzapine of 50 μmol/L and 100 μmol/L. ② Olanzapine's effects on Bax expression in PC12 cell apoptosis induced by β-amyloid 25-35 Bax expression increased in PC12cells due to exposure to β-amyloid 25-35 of 0.01 μmol/L, 2 μmol/L and 20 μmol/L, but it could be suppressed if pretreated with olanzapine of 50 μmol/L. ③ Effect of olanzapine on caspase-3 expression in PC12apoptotic cells induced by β-amyloid 25-35 There was no change in PC12cells induced by 0.001 μmol/L or 0.01 μmol/L of β-amyloid, as well as in PC12 cells pretreated with 50 μmol/L olanzapine. However, caspase-3 expression obviously increased in PC12 cells exposed to 2 μmol/L and 20 μmol/L of β-amyloid 25-35, and it could be suppressed by pretreatment with 50 μmol/L of olanzapine.

CONCLUSION:

① β-amyloid 25-35 can induce the high expression of cell apoptosis related Bax and caspase-3 in vitro cultured PC12 cells. ②Olanzapine can reduce the expression, thus enhancing the survival rate of PC 12 cells.