Inhibitory effects of constituents ofGastrodia elata Bl. on glutamate-induced apoptosis in IMR-32 human neuroblastoma cells

Abstract

The inhibitory effects of the constituents ofGastrodia elata Bl. (GE) on glutamate-induced apoptosis in human neuronal cells were investigated using IMR32 human neuroblastoma cells. Glutamate (GLU) induced DNA fragmentation, a hallmark of apoptosis, in a dose-dependent manner. GLU also induced a slow and sustained increase in intracellular Ca²⁺ concentration. Treatment with EGTA, an extracellular Ca²⁺ chelator, in a nominal Ca²⁺-free buffer solution abolished the GLU-induced intracellular Ca²⁺ increase, indicating that GLU stimulated Ca²⁺ influx pathway in the IMR32 cells. BAPTA, an intracellular Ca²⁺ chelator, significantly inhibited the GLU-induced apoptosis assessed by the flow cytometry measuring hypodiploid DNA content indicative of apoptosis, implying that intracellular Ca²⁺ rise may mediate the apoptotic action of GLU. Vanillin (VAN) and p-hydroxybenzaldehyde(p-HB), known constituents of GE, significantly inhibited both intracellular Ca²⁺ rise and apoptosis induced by GLU. These results suggest that the apoptosis-inhibitory actions of the constituents of GE may account, at least in part, for the basis of their antiepileptic activities. These results further suggest that intracellular Ca²⁺ signaling pathway may be a molecular target of the constituents of GE.