Stevioside enhances apoptosis induced by serum deprivation in PC12 cells.

In the laboratory, using a PC12 cell system, studies have been conducted on the effects of various chemicals on apoptosis, as it is considered to be an essential part of normal development, maintenance, and defense in organisms. Stevioside is a natural sweetener extracted from the leaves of Stevia rebaudiana. Since it is widely used as a sugar replacement, it was decided to evaluate the toxicological effects of low concentrations of stevioside on apoptosis induced by serum deprivation using the PC12 cell system. It was found that based on data from DNA electrophoresis and TUNEL signal assays stevioside enhanced apoptosis induced by serum deprivation. This enhancement was caused by increased expression of Bax and of cytochrome c released into the cytosol. These findings suggest that stevioside affects the regulation of the normal apoptotic condition. Further investigation will be needed to clarify the detailed mechanism of the enhancement due to the treatment with stevioside.

Bisphenol-A suppresses neurite extension due to inhibition of phosphorylation of mitogen-activated protein kinase in PC12 cells.

An endocrine disrupter, bisphenol-A is widely used in the production of plastics and coatings. Recently, it was reported that bisphenol-A affected neurotransmitters in the mammalian brain. On the basis of these reports, it was considered that bisphenol-A affected neuronal differentiation. In this study, the morphological changes in nerve growth factor (NFG)-induced differentiation caused by bisphenol-A were confirmed using a PC12 cell system. When a low concentration of bisphenol-A was added to medium containing NGF, it inhibited neurite extension. In addition, to clarify whether bisphenol-A affects the early and late stages of the NGF-signaling pathway in cell differentiation, changes of phosphorylation of MAP kinases and cAMP-response element binding protein (CREB) in PC12 cells treated with and without BPA in medium containing NGF were investigated using western blot analysis. As results, bisphenol-A significantly inhibited phosphorylation of CREB and ERK1/2 MAPK.

Protective effect of lignophenol derivative from beech (Fagus crenata Blume) on copper- and zinc-mediated cell death in PC12 cells.

Lignophenol, prepared using a phase-separation system, is a derivative of lignin, which is one of the components in the plant cell wall, and possesses high phenolic function, high stability and antioxidant properties. However, little is known about the beneficial effect of lignophenol. In this study, we investigated the protective effect of lignophenol from the beech tree (Fagus crenata Blume) on copper- and zinc-mediated apoptosis in PC12 cells by using DNA fragmentation and TUNEL assays. In DNA fragmentation assays, the DNA ladder patterns in the PC12 cells treated with 200 microM Cu and 200 microM Zn were enhanced, whereas the DNA ladder pattern was hardly observed in these cells treated with 20 mM lignophenol. In the TUNEL assay, TUNEL signals increased significantly in the untreated PC12 cells exposed to 200 microM Cu compared with the control. In contrast, the degree of apoptosis in the 20 mM lignophenol-treated cells was significantly lower than in the untreated cells, indicating that lignophenol inhibited Cu-induced apoptotic cell death in PC 12 cells. In the 200 microM Zn-exposed group, the degree of apoptosis in the 20 mM lignophenol-treated cells was also low compared with the untreated cells. In conclusion, these results suggest that lignophenol plays a role in protecting against Cu- and Zn-mediated PC12 apoptotic cell death.