Neurotrophin-3 reduces apoptosis induced by 6-OHDA in PC12 cells through Akt signaling pathway

Previous work has demonstrated that 6-hydroxydopamine (6-OHDA) induces apoptosis in PC12 cells. The goal of the present study was to investigate the mechanisms underlying the protection by neurotrophin-3 (NT-3) against 6-OHDA-induced apoptosis in PC12 cells. Treatment of PC12 cells with 6-OHDA resulted in activation of caspase-3 and subsequent apoptosis, as detected by TUNEL staining. In addition, Akt phosphorylation was decreased following 6-OHDA treatment. Pretreatment with NT-3 reduced the percentage of apoptotic cells and caspase-3 activity induced by 6-OHDA and suppressed the cleavage of caspase-3 and Poly(ADP-ribose) polymerase (PARP) with a significant decrease in cell viability. Moreover, Akt phosphorylation was enhanced and 6-OHDA-induced chromatin condensation was suppressed by NT-3. Such NT-3-evoked suppression in chromatin condensation was reversed by anti-TrkA antibody receptor blockade. Further study revealed that LY294002, an inhibitor of PI3-kinase (a molecule upstream of Akt), enhanced 6-OHDA-induced apoptosis. These data indicate that NT-3 prevents 6-OHDA-induced apoptosis in PC12 cells via activation of PI3-kinase/Akt pathway.