Neuroprotective effects of a Coeloglossum viride var. Bracteatum extract in vitro and in vivo.

The excessive release and accumulation of glutamate in the brain is known to be associated with excitotoxicity. CE, an extract derived from the plant Coeloglossum viride var. Bracteatum, exerted neuroprotective effects against amyloid toxicity and oxidative stress in cortical neurons. The aims of this study are to examine whether CE also attenuates glutamate neurotoxicity in rat primary cultured cortical neurons and to determine the effect of CE in vivo. According to the results of MTT, LDH release, and TUNEL assays, the CE treatment significantly reduced glutamate-induced neurotoxicity in a dose-dependent manner. Moreover, the protective effects of CE were blocked by an Akt inhibitor, LY294002, suggesting that the PI3K/Akt signalling pathway is involved in the neuroprotective effects of CE. In addition, CE might regulate the PKC-GluA2 axis to prevent neuronal apoptosis. CE also protected against dopaminergic neuronal loss in a mouse model of MPTP-induced PD. Based on our results, CE exerted neuroprotective effects both in vitro and in vivo, thus providing a potential therapeutic target for the treatment or prevention of neurodegeneration.