Neuroprotective effects of Dendrobium alkaloids on rat cortical neurons injured by oxygen-glucose deprivation and reperfusion

In this study we investigated the protective effects of alkaloids from Dendrobium spez. on cortical neurons injured by oxygen-glucose deprivation/reperfusion (OGD/RP) in vitro. Rat primary cultured cerebral cortical neurons were investigated at different time points of OGD/RP. The MTT assay and the lactate dehydrogenase (LDH) release were used to determine cell viability. The concentration of intracellular free calcium [Ca2+]i and mitochondrial membrane potential (MMP) were determined to evaluate the degree of neuron damage. Morphologic changes of neurons following OGD/RP were examined by electron microscope. To evaluate neuron apoptosis, flow cytometry was performed and the expressions of caspase-3 and caspase-12 mRNA were examined by real-time quantitative PCR during OGD 2 h/RP 12 h. Treatment with Dendrobium alkaloids (0.025∼2.5 mg/l) significantly attenuated neuronal damage, with evidence of increased cell viability, decreased cell apoptosis, and decreased cell morphologic impairment. Furthermore, Dendrobium alkaloids inhibited [Ca2+]i elevation, increased MMP and decreased the expressions of caspase-3 and caspase-12 in a concentration-dependent manner at OGD 2 h/RP 12 h. Dendrobium alkaloids have significantly protective effects on OGD/RP-induced neuronal damages in rat primary neuron cultures. The protection against OGD/RP-induced apoptosis appears to be mediated through blocking the decrease in MMP and increase in [Ca2+]i, as well as by down-regulating mRNA expression of caspase-3 and caspase-12.