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Extracts of Cynomorium songaricum protect SK-N-SH human neuroblastoma cells against Aβ25–35 induced cytotoxicity potentially through their anti-apoptotic activity
Introduction: It has been demonstrated that apoptosis is a feature of chronic and acute neurodegenerative diseases. Similar cell death signalling pathways might be activated in neurodegenerative diseases by abnormal protein structures, such as amyloid fibrils in Alzheimer's disease (AD). Bcl-2, Bax and caspase-3 are well known to play important roles in the process of apoptosis. Stems of Cynomorium songaricum have been used for treating neuronal diseases traditionally in China for long periods. In this study, we evaluated the protective effect of extracts of C. songaricum against Aβ25–35 induced apoptosis on SK-N-SH cells by determination of cell viability and levels of Bcl-2, Bax and caspase-3. Method: Firstly, for investigating possible neuroprotective effects, the SK-N-SH cells were cultured at a density of 1.5 '104 cells/well in 96-well plates. The cells were treated with extracts of C. songaricum at concentrations of 100, 10, 1 and 0.1µg/ml 4h before addition of Aβ25–35 (20µM). Cell viability was quantified using the MTT test after 96hrs. According to the results of the MTT test, the EtOAc- and MeOH-extracts of C. songaricum were selected to be further evaluated concerning their effect on the expression of Bcl-2, Bax and caspase-3 through immunocytochemical assays . Results and discussion: In our study, the EtOAc extract of C. songaricum significantly attenuated Aβ25–35 induced cell death at concentrations of 100 and 10µg/ml. At the same time, the extract was able to reverse the down-regulation of Bcl-2 and up-regulation of caspase-3 which are induced in the SK-N-SH cells by Aβ25–35. On the other hand, it has no significant effect on the expression of Bax. Thus, the EtOAc extract of C. songaricum might protect the SK-N-SH cells against cytotoxicity and apoptosis induced by Aβ25–35 partly due to its ability in reducing the over expression of caspase-3 as well as reversing the down-regulation of Bcl-2.
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