Vitamin K2 protects PC12 cells against Aβ (1-42) and H2O2-induced apoptosis via p38 MAP kinase pathway

Abstract

Alzheimer’s is an age-related disease with a hallmark of progressive loss of memory formation followed by a damage in the brain function due to the neural degeneration and extracellular beta-amyloid (Aβ) plaques accumulation. This study examines the protective effects of vitamin K2 on toxicity induced by (Aβ) (1-42) and H2O2 in PC12 cells as an appropriate model of Alzheimer’s cell damage. PC12 cells pretreated with vitamin K2 (5–200 μM) for 4, 24 and 48 h, and exposed to either Aβ (25 µM) for 48 h or H2O2 (150 µM) for 24 h. Then the protective, antioxidant and anti-apoptotic effects of vitamin K2 in PC12 cells were investigated. Vitamin K2 pretreatment (5–200 μM) significantly decreased the Aβ (1-42) and H2O2 cytotoxicity. In addition, vitamin K2 could attenuate reactive oxygen species (ROS) level after exposure of cells to H2O2 for 24 h and Aβ (1-42) for 48 h. Cell apoptosis significantly increased following application of Aβ (1-42) (25 μM) and H2O2 (150 µM) compared to control. However, flow cytometry histograms of PI-stained cells after pretreatment with vitamin K2 (20 and 50 μM) showed significantly reduced apoptosis. Vitamin K2 increased the amount of glutathione after exposure of cells to H2O2 for 24 h and Aβ (1-42) for 48 h. Western blot analysis of PC12 cells showed that 25 μM Aβ (1-42) and 150 µM H2O2 treatment could increase Bax, PARP cleavage, Phospho-p38 MAPK. Moreover, the activated form of caspase 3 proteins led to the reduction in the Bcl-2. Real-time PCR of PC12 cells showed that 150 µM H2O2 treatment increased the ratio of Bax/Bcl-2 while vitamin K2 (20 and 50 μM) reduced the rate. According to these findings, it seems that vitamin K2 possess anti-apoptotic and antioxidant effects and suggests that vitamin K2 may be a valuable protective candidate against the progression of Alzheimer’s disease via inactivating p38 MAP kinase pathway.