Melissa officinalis acidic fraction protects cultured cerebellar granule neurons against beta amyloid-induced apoptosis and oxidative stress

Objective: Extracellular deposition of the beta-amyloid [A beta] peptide, which is the main finding in the pathophysiology of Alzheimer's disease [AD], leads to oxidative damage and apoptosis in neurons. Melissa officinalis [M. officinalis] is a medicinal plant from the Lamiaceae family that has neuroprotective activity. In the present study we have investigated the protective effect of the acidic fraction of M. officinalis on A beta-induced oxidative stress and apoptosis in cultured cerebellar granule neurons [CGN]. Additionally, we investigated a possible role of the nicotinic receptor

Materials and Methods: This study was an in vitro experimental study performed on mice cultured CGNs. CGNs were pre-incubated with different concentrations of the acidic fraction of M. officinalis for 24 hours, followed by incubation with A beta for an additional 48 hours. CGNs were also pre-incubated with the acidic fraction of M. officinalis and mecamylamin, followed by incubation with A beta. We used the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide [MTT] assay to measure cell viability. Acetylcholinesterase [AChE] activity, reactive oxygen species [ROS] production, lipidperoxidation, and caspase-3 activity were measured after incubation. Hochst/annexin V- fluorescein isothiocyanate [FITC]/propidium iodide [PI] staining was performed to detect apoptotic cells

Results: The acidic fraction could protect CGNs from A beta-induced cytotoxicity. Mecamylamine did not abolish the protective effect of the acidic fraction. AChE activity, ROS production, lipid peroxidation, and caspase-3 activity increased after A beta incubation. Pre-incubation with the acidic fraction of M. officinalis ameliorated these factors and decreased the number of apoptotic cells

Conclusion: Our results indicated that the protective effect of the acidic fraction of M. officinalis was not mediated through nicotinic receptors. This fraction could protect CGNs through antioxidant and anti-apoptotic activities

Chlorpyrifos toxicity in mouse cultured cerebellar granule neurons at different stages of development: additive effect on glutamate-induced excitotoxicity

Objective: Chlorpyrifos [CPF] is a neurotoxic organophosphorus [OP] insecticide. Its mechanism of action includes oxidative stress, excitotoxicity, and inhibition of the acetylcholinesterase enzyme [AChE]. The aim of the present study is to investigate CPF toxicity in mature and immature cerebellar granule neurons [CGNs], as well as its effect on glutamate induced excitotoxicity

Materials and Methods: this study was an in vitro experimental study performed on mice cultured CGNs. Immature and mature neurons were exposed to different concentrations of CPF [1-1000 [micro]M] and glutamate [10-600 [micro]M] for 48 hours after which we used the MTT assay to measure cytotoxicity. Immature neurons had exposure to CPF for 5 days in order to evaluate the cytotoxic effect on developing neurons. Mature neurons received sub-lethal concentrations of CPF [10, 100 [micro]M] combined with different concentrations of glutamate. AChE activity and reactive oxygen species [ROS] generation were assessed after treatments

Results: immature CGNs had increased sensitivity to CPF toxicity compared to mature neurons. We observed significantly greater ROS production in immature compared to mature neurons, however AChE activity was more inhibited in mature neurons. Although CPF toxicity was not well correlated with AChE inhibition, it correlated well with ROS production. Glutamate toxicity was potentiated by sub-lethal concentration of CPF, however glutamate induced ROS production was not affected. The results suggested that CPF potentiated glutamate toxicity by mechanisms other than oxidative stress

Conclusion: CPF toxicity differed in mature and immature neurons. Potentiated glutamate toxicity by CPF implied that CPF exposure might be a risk factor for neurodegenerative disease

[Evaluation of Cr [VI] induced neurotoxicity and oxidative stress in PC12 cells]

Objective: Hexavalent chromium [Cr [VI]] compounds are well-known environmental contaminants generated from industrial processes. Several studies have reported the harmful effects of Cr [VI] on different organs, however, little is known about neurotoxic effects of Cr [VI]. The aim of this study is to investigate the toxic effects of Cr [VI] on PC12 cells

Methods: PC12 cells were cultured following standard protocol and exposed to various concentrations [1-100 microM] of potassium dichromate [K2Cr2O7] for 24, 48 and 72 h. After exposure, cell viability was measured by the MTT assy. Also following exposure, production of reactive oxygen species [ROS] and lipid peroxidation were measured

Results: Potassium dichromate induced significant cell death in PC12 cells. The IC50 values for cytotoxicity were 22.02 for 24 h, 1.88 for 48 h, and 1.85 for 72 h of exposure. Significant differences between IC50 for 24 h of exposure compared to 48 and 72 h of exposure were observed [p<0.05]. ROS production and lipid peroxidation significantly increased in the Cr [VI] treated groups compared to the control group [p<0.05]

Conclusion: The results indicated that Cr [VI] induced dose and time dependent cytotoxicity in PC12 cells which indicated neurotoxic effects of Cr [VI]. Mechanisms of Cr [VI] induced toxicity have not been fully determined, however increased production of ROS and lipid peroxidation in Cr [VI] treated groups demonstrated that oxidative stress might be involved in neurotoxicity of Cr [VI]