Paeoniae radix has been widely used for its anti-allergic, anti-inflammatory and analgesic effects, and demonstrated to have anticonvulsant, memory enhancing and anxiolytic activities. The present study was performed to examine the protective effect of methanol extract of Paeoniae radix (PR) from Paeoniae Japonica Miyabe et Takeda (Paeoniaceae) on hydrogen peroxide (H2O2)-induced neurotoxicity using cultured rat cerebral cortical neuron. H2O2 produced a concentration-dependent reduction of neuronal viability, PR, over a concentration range of 10 to 100 μg/ml showed concentration-dependent decrease of the H2O2(100 μM)-induced neuronal cell death, as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-di-phenyl-tetrazolium bromide assay and the number of apoptotic nuclei, evidenced by Hoechst 33342 staining. PR (100 μg/ml inhibited 100 μM H2O2-induced elevation of the cytosolic Ca2+ concentration ([Ca2+]c), which was measured by a fluorescent dye, flue-4 AM. PR (50 μg/ml inhibited glutamate release into medium induced by 100 μM H2O2, which was measured by HPLC, and generation of reactive oxygen species (ROS). These results suggest that PR may mitigate the H2O2-induced neurotoxiciy by interfering with the increase of [Ca2+]c, and then inhibiting glutamate release and generation of ROS in cultured neurons.

• Yeon-Hee Seong
• Kyung-Sik Song
• Ju-Hyun Lee
• Ju-Yeon Ban
• Min-Su Park