Protective Effects of Flavonoid Extract from Apocynum venetum Leaves Against Corticosterone-Induced Neurotoxicity in PC12 Cells

Depression is a major psychiatric disorder affecting nearly 21% of the world population and imposes a substantial health burden on society. Although significant progress has been made in depression research, the common molecular mechanism of antidepressants is still far from clearly understood. The neuroprotective effect of antidepressants has been proposed as a possible mechanism. Although Apocynum venetum (AV) L. (Apocynaceae) was previously shown to produce an antidepressant-like effect in the tail suspension test, the mechanisms underlying such antidepressant-like effect are yet to be understood. In this work, we studied the neuroprotective effect of AV leaf flavonoid extract in corticosterone-induced neurotoxicity, using PC12 cells as a suitable in vitro model of depression. Cell viability was quantitated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The release amount of lactic dehydrogenase (LDH) and intracellular Ca2+ concentration were measured using kit, cell period change was tested by flow cytometry, and transcript abundances of brain-derived neurotrophic factor (BDNF) and microtubule-associated protein 4 (MAP4) were determined by real-time RT-PCR. The results showed that AV extract (25, 50, and 100 μg/ml) increased the A490 nm values, but decreased LDH release and Ca2+ concentration, suppressed the apoptosis of PC12 cells and up-regulated BDNF and MAP4 transcript abundances compared with the corresponding corticosterone-treated group. These results suggest that the AV extract could generate a neuroprotective effect on corticosterone-induced neurotoxicity in PC12 cells, pointing to a possible action pathway by decreasing the Ca2+ concentration and up-regulating BDNF and MAP4 genes.