Moutan Cortex Extract Inhibits Amyloid ${\beta}$ Protein (25-35)-induced Neurotoxicity in Cultured Rat Cortical Neurons

Moutan cortex, the root bark of Paeonia suffruticosa Andrews (Paeoniaceae), has pharmacological effects such as anti-inflammatory, antiallergic, analgesic and antioxidant activities. We investigated a methanol extract of Moutan cortex for neuroprotective effects on neurotoxicity induced by amyloid β protein (Aβ) (25-35) in cultured rat cortical neu- rons. Exposure of cultured cortical neurons to 10 µM Aβ (25-35) for 24 h induced neuronal apoptotic death. Moutan cortex inhibited 10 µM Aβ (25-35)-induced neuronal cell death at 30 and 50 / , which was measured by a 3-(4,5-dimethylthia- zol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. Moutan cortex inhibited 10 µM Aβ (25-35)-induced elevation of intracellular calcium concentration ((Ca 2+ )i), and generation of reactive oxygen species (ROS) which were measured by fluorescent dyes. Moutan cortex also inhibited glutamate release into medium induced by 10 µM Aβ (25-35), which was measured by HPLC. These results suggest that Moutan cortex prevents Aβ (25-35)-induced neuronal cell damage by interfering with the increase of (Ca 2+ )i, and then inhibiting glutamate release and ROS generation. Moutan cortex may have a therapeutic role in preventing the progression of Alzheimer's disease.