Objective:

2

To explore the mechanism of crocin

a major active component of Crocus sativus (Zanghonghua)

in regulating amyloid beta (Aβ) generation

endoplasmic reticulum (ER) stress

and autophagy in neuronal cells

with potential therapeutic applications in Alzheimer's disease (AD).

Methods:

2

Mouse neuroblastoma Neuron2a (N2a) cells stably transfected with the human amyloid precursor protein (APP) Swedish mutant was used as a cellular model for AD (N2a/APP). Control cells were vector transfected (N2a/vector). The effects of 3 different doses of crocin on reactive oxygen species (ROS) generation

cytosolic calcium

and apoptosis were evaluated by flow cytometry. Aβ levels were determined by enzyme-linked immunosorbent assay. APP processing and ER stress proteins expressions were determined by Western blot. Autophagosome formation was evaluated by autophagy detection kit and confocal microscope.

Results:

2

Crocin inhibited APP expression in N2a/APP cells and promoted α-cleavage of APP processing

while modestly reduced beta-secretase 1 (BACE1) and presenilin 1 (PS1

P

<

0.05 or

P

<

0.01). ER stress markers

including the binding immunoglobulin protein/78-kD glucose-regulated protein (Bip/GRP78) and C/EBP homologous protein (CHOP)

were elevated in N2a/APP cells compared to N2a/vector cells (

P

<

0.05). Crocin could effectively reduce the levels of ER stress (

P

<

0.05 or

P

<

0.01). In addition

crocin enhanced autophagy by promoting formation of autophagosome (

P

<

0.05 or

P

<

0.01).

Conclusion:

2

Crocin significantly inhibited Aβ generation by promoting α-cleavage of APP processing

inhibiting ER stress-associated unfolded protein response

and regulating autophagy.