Aims: The progressive accumulation of beta-amyloid peptide (Abeta), in the form of senile plaques, has been recognized as one of the major causes of Alzheimer's disease (AD) pathology. Increased production of Abeta and the aggregation of Abeta to oligomers have been reported to trigger neurotoxicity, oxidative damage and inflammation. Furthermore, Abeta-induced tau hyperphosphorylation and neurotoxicity are downstream of Abeta. Therefore, we studied the possible neuroprotective effects of caffeic acid against Abeta-induced toxicity.
Main methods: Treatment of PC12 cells with 10 microM Abeta (25-35) for 24 h significantly decreased the cell viability; this was accompanied by an increase in intracellular calcium levels and tau phosphorylation with GSK-3beta (glycogen synthase kinase-3beta) activation (phosphorylation).
Key findings: However, pretreatment of the PC12 cells with 10 and 20 microg/ml of caffeic acid, for 1 h prior to Abeta, significantly reversed the Abeta-induced neurotoxicity by attenuating the elevation of intracellular calcium levels and tau phosphorylation.
Significance: Taken together, these results suggest that caffeic acid protected the PC12 cells against Abeta-induced toxicity. In addition, the neuroprotective mechanisms of caffeic acid against Abeta attenuated intracellular calcium influx and decreased tau phosphorylation by the reduction of GSK-3beta activation.