Monday, September 27, 2010

Propolis Flavonoid Has Neuroprotective Properties

Astaxanthin Upregulates Heme Oxygenase-1 Expression Through ERK1/2 Pathway and Its Protective Effect Against Beta-Amyloid-Induced Cytotoxicity in SH-SY5Y Cells
Brain Research, Article in Press

Astaxanthin (ATX), the most abundant flavonoids in propolis, has been proven to exert neuroprotective property against glutamate-induced neurotoxicity and ischemia–reperfusion-induced apoptosis.

Previous study have revealed that ATX can rescue PC12 cells from Aβ25–35-induced apoptotic death. However, the mechanisms by which ATX mediates its therapeutic effects in vitro are unclear. In the present study, we explored the underlying mechanisms involved in the protective effects of ATX on the Aβ25–35-induced cytotoxicty in SH-SY5Y cells.Pre-treatment with ATX for 4 h significantly reduced the Aβ25–35-induced viability loss, apoptotic rate and attenuated Aβ-mediated ROS production.

In addition, ATX inhibited Aβ25–35-induced lowered membrane potential, decreased Bcl-2/Bax ratio. We also demonstrated that ATX could prevent the activation of p38MAPK kinase pathways induced by Aβ. Moreover, we for the first time have revealed the ATX increased antioxidant enzyme heme oxygenase-1 (HO-1) expression in concentration-dependent and time-dependent manners, which were correlated with its protective effect against Aβ25–35-induced injury. We also demonstrated that the specific ERK inhibitor, PD98059, concentration-dependently blocked on ATX-induced HO-1 expression.

Taken together, these findings suggest that astaxanthin can induce HO-1 expression through activation of ERK signal pathways, thereby protecting the SH-SY5Y cells from Aβ25–35-induced oxidative cell death.

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