Methanol Extract of Paeonia Japonica Root Protects Cultured Rat CorticalNeurons Against Oxidative Damage Induced by Hydrogen Peroxide

Paeoniae radix has been widely used for its anti - allergic, anti - inflammatory and analgesic effects, and demon strated 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 Paeonia Japonica Miyabe et Takeda (Paeoniaceae) on hydro gen peroxide (H 2 O 2 ) - induced neurotoxicity using cultured rat cerebral cortical neuron. H 2 O 2 produced a concentration - depen dent reduction of neuronal viability. PR, over a concentration range of 10 to 100 ㎍ / ㎖ showed concentration - dependent decrease of the H 2 O 2 ( 1 0 0 µ M ) - induced neuronal cell death, as assessed by a 3 - [4,5 - dimethylthiazol - 2 - yl] - 2,5-di - phenyl - tetrazo lium bromide assay and the number of apoptotic nuclei, evidenced by Hoechst 33342 staining. PR (100 ㎍ / ㎖ ) inhibited 100 µM H 2 O 2 - induced elevation of the cytosolic Ca 2+ concentration ([Ca 2+ ] c ), which was measured by a fluorescent dye, fluo - 4 AM. PR (50 ㎍ / ㎖ ) i n h i b i t e d g l u t a m a t e r e l e a s e i n t o m e d i u m i n d u c e d b y 1 0 0 µ M H 2 O 2 , which was measured by HPLC, and generation of reactive oxygen species (ROS). These results suggest that PR may mitigate the H 2 O 2 - induced neurotoxiciy by interfering with the increase of [Ca 2+ ] c , and then inhibiting glutamate release and generation of ROS in cultured neurons.