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The 1-methyl-4-phenyl-pyridinium ion (MPP(+)), an active metabolite of the neurotoxin, N-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP), induces death in rat pheochromocytoma (PC12) cells, suggesting a cell model of Parkinson's disease (PD). However, most of the toxic mechanisms remain illusive. In this study, we have found that MPP(+) induced apoptotic cell death in PC12 cells as measured by the MTT assay and annexin V-FITC staining. Besides, MPP(+) also resulted in decreased mitochondrial membrane potential and increased mitochondrial free radical formation as imaged by the staining of TMRE or MitoSOX, respectively, confirming the neurotoxic effect of MPP(+) by interfering with mitochondrial functions. Western blot analysis indicated that MPP(+) differentially regulated the expressions and over-oxidation of thioredoxin systems and peroxiredoxins. Since these enzymes are known to prevent oxidative stress and apoptosis, these evidences could be regarded as a novel neurotoxic mechanism of MPP(+) and also provide an alternative view of developing drug therapies for PD., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Aims of the Study: Although ginseng root possesses dominant central therapeutic effects and has recently undergone investigations for treating different neuronal diseases, most of its mechanisms are still unknown. Therefore, the neuroprotective mechanisms of ginseng were studied., Materials and Methods: The protection afforded by different methanol extracts of Panax ginseng (PG) was tested in a serum deprivation-induced apoptotic model using neuronal-like pheochromocytoma (PC12) cells. An MTT assay, annexin V-FITC staining, and Western blots were, respectively, applied to identify the viability of cells, the apoptotic form of cell death, and the activity of antiapoptotic signaling., Results: The known antiapoptotic PI3-K/Akt and MEK/ERK pathways in this system were ruled out due to failure of LY 294002 and PD 98059 to block the protection by PG. A protein kinase A (PKA) inhibitor was found to block the protection by PG and PG-induced CREB phosphorylation, suggesting that the PKA/CREB pathway mediates the protective effect of PG. Downregulation of classical and novel PKCs failed to block the protection by PG, while an atypical PKC inhibitor blocked protection by PG., Conclusions: PKA and atypical PKC are important for the protection afforded by PG in preventing serum deprivation-induced PC12 cell apoptosis.

Abstract: Antrodia camphorata (A. camphorata) is a rare medicinal fungus with antioxidative, vasorelaxtative, anti-inflammatory and anti-hepatitive effects. However, the neuroprotective effect has not been studied. By using serum deprivation-induced apoptosis in neuronal-like PC12 cells as a cell stress model, we found that A. camphorata is effective in preventing serum-deprived apoptosis. Inhibitors of both a serine/threonine kinase and a specific protein kinase A (PKA) inhibited the protective effect of A. camphorata, indicating that A. camphorata prevents serum-deprived PC12 cell apoptosis through a PKA-dependent mechanism. A transcription inhibitor, actinomycin D, and a protein synthesis inhibitor, cyclohexamide, both attenuated the protective effect of A. camphorata, indicating a requirement for gene expression for protection by A. camphorata. On the other hand, A. camphorata also increased phosphorylated CREB, a transcription factor, which is H-89-inhibitable in this study, suggesting the possibility that A. camphorata prevents serum deprivation-induced PC12 cell apoptosis through a PKA/CREB-dependent pathway. [Copyright &y& Elsevier]

Abstract: Ethnopharmacological relevance: Ligusticum chuanxiong (LC) as a common component in many traditional Chinese medicinal formulas and decoctions has been used to treat different central nervous diseases, suggesting a neuroprotective function. Aim of the study: To investigate the functional roles of mitogen-activated protein kinases (MAPKs) in mediating the neuroprotection of LC. Materials and methods: Different extractions of LC were applied with or without MAPK inhibitor to test their protection against serum deprivation-induced apoptosis in rat neuronal-like pheochromocytoma (PC12) cells as revealed by an MTT assay or Hoechst staining. Western blot was used to identify the activations of MAPKs. Results: The most effective butanol extraction (LC-BuOH) was used in the following experiments. LC-BuOH reversed serum deprivation-induced decreased phosphorylation of extracellular signal-regulated kinase (ERK) and increased phosphorylation of c-Jun NH2-terminal kinase (JNK) and p38, the family of MAPKs. A PKA inhibitor, blocked the protection of LC-BuOH and partially blocked LC-BuOH-induced alterations in MAPKs, suggesting that the LC-BuOH regulates MAPKs through both PKA-dependent and -independent pathways. Although PD 98059, an inhibitor of MEK which activates ERK, blocked LC-BuOH-induced ERK phosphorylation, it did not block the protection of LC-BuOH. Conclusions: LC-BuOH mediates protection by suppressing JNK/p38 instead of activating ERK activity. [Copyright &y& Elsevier]

Abstract: Methamphetamine (METH) is an abusive psychostimulant that induces neuronal cell death/degeneration in experimental animals and humans. METH-induced apoptosis in rat pheochromocytoma cells was utilized to study the neurotoxic mechanism. During METH intoxication, we found that peroxiredoxins and thioredoxins/thioredoxin reductases (peroxiredoxin reducing systems) which are known to prevent oxidative stress and apoptosis were differentially downregulated and upregulated, respectively. We also found not only the free radicals but also the oxidative forms of peroxiredoxin and thioredoxin were increased, indicating the dysfunction of these enzymes. Thus, METH-induced differential regulation and oxidation of peroxiredoxins and thioredoxin may be an important mechanism for apoptosis. [Copyright &y& Elsevier]

Abstract: Antrodia cinnamomea (formerly named Antrodia camphorata) is a rare medicinal fungus. We previously reported that it exhibits antioxidative, vasorelaxative, anti-inflammatory, and anti-angiogenic effects. When serum deprivation-induced apoptosis in neuronal-like PC12 cells was used as a stress model, the extract of A. cinnamomea displayed effectiveness in preventing serum-deprived apoptosis. Since our previous data show that the extract of A. cinnamomea contains adenosine (ADO), we attempt to investigate if the active component is ADO and to identify its targeting site in this study. After pre-incubation with ADO deaminase, neither ADO nor the extract of A. cinnamomea exerted any protection, demonstrating that the active component of A. cinnamomea is ADO. Furthermore, an ADO A2A receptor (A2A-R) antagonist was used and was able to block the protective effects of ADO and the extract of A. cinnamomea, demonstrating that the ADO targeting site in this model is A2A-R. Taken together, the protective effect of A. cinnamomea is owed to its active component, ADO, which acts through activation of A2A-R to prevent serum deprivation-induced PC12 cell apoptosis. [Copyright &y& Elsevier]