Potential protection of curcumin against intracellular amyloid beta-induced toxicity in cultured rat prefrontal cortical neurons.

Recently the neuronal toxicity of intracellular amyloid beta (iAbeta) in Alzheimer's disease is attracting more and more attention. The present study explored the effects of curcumin on the iAbeta-induced toxicity in primary cultured rat prefrontal cortical neurons. The cell viability of primary cultured prefrontal cortical neurons decreased significantly after virus driven transfection of Abeta from 1 day to 7 days. Interestingly, administration of 1 microM, 10 microM or 20 microM of curcumin significantly inhibited the iAbeta-induced toxicity in primary cultured rat prefrontal cortical neurons tested by MTT and LDH release assays. We further studied the involvements of apoptotic or neuroprotective pathway proteins in curcumin protection against iAbeta-induced cytotoxicity in primary cultured rat prefrontal cortical neurons. The results demonstrated that the contents of activated caspase-3 increased significantly by iAbeta, while curcumin significantly inhibited the iAbeta-induced increases of activated caspase-3 tested by Western blot. And the contents of p-AKT decreased significantly after iAbeta treatment, while administration of curcumin significantly inhibited the iAbeta-induced decreases in the contents of p-AKT. The results suggest that curcumin may play a protective effect in primary cultured rat prefrontal cortical neurons against iAbeta-induced cytotoxicity, and both AKT and caspase-3 are involved in the curcumin-induced protective effects.