Study On The Neurotoxicity Effect And Its Mechanism Of Rotenone On The Dopaminergic Cells

Rotenone is one kind of pesticide. It is also a high-affinity inhibitor of complex I of mitochondrial electron transfer chain which can enhance ROS formation. PD-related studies showed that exposure to rotenone reproduces features of PD, including selective nigrostriatal dopaminergic degeneration andα-synuclein-positive cytoplasmic inclusions. Human neuroblastoma SH-SY5Y cells were regarded as dopaminergic cells because it can generate and secrete dopamine. However, the exact neurotoxicity mechanism of rotenone on dopaminergic neuron is unknown. Recent findings suggest that neurons which are at risk of neurodegeneration are also at risk of re-initiating a cell cycle process, and failure of cell cycle regulation might be a root cause of several neurodegenerative disorders. The effect of rotenone on the cell cycle distribution of SH-SY5Y cells has rarely been reported. The aim of the present study, therefore, is to investigate the toxic effect and mechanism of rotenone on SH-SY5Y cells and dopaminergic neurons, expecially to explore the the effect and mechanism of rotenone on the cell cycle distribution which may lead to cell death. Hope it can provide new experimental basis for the etiology of PD.In the present study, we investigated the toxic effect and mechanism of rotenone on SH-SY5Y cells. The results showed that rotenone decreased the cell viability on the dose-dependent and time-dependent mode, damaged the normal morphology of the cells, and induced multinucleation and morphologic character of apoptosis, as well as caspase-3 activity. Cell cycle analysis showed that after treatment with 250nM rotenone, the population of cells in the G2/M phase transiently increased at 24 hr and decreased gradually afterwards. While the population of cells in the G2/M phase decreased, the population of cells in the sub-G1 and S phase increased. It demonstrates that rotenone induced the transient G2/M arrest in the SHSY5Y cells. Western blotting analysis showed that the levels of cyclin B1 and p-cdc2 (Tyr15) increased and reached the peak at 6 hr and 24 hr of exposure to rotenone, respectively, which was parallel with the transient G2/M arrest. The level of p53 protein is continuely increased during 72 hr of exposure to rotenone. These data suggest that rotenone-induced cell cycle arrest is controlled by these checkpoint regulatory proteins. Over-expression of p53 induced by rotenone may contribute to the alteration of cell cycle distribution and cell death.In the present study, we also investigate the toxic effect of rotenone on the dapaminegic neurons. We established the animal model by unilaterally infusing rotenone into substantia nigra pars compacta (SNpc) of rats. The animals were selected with the amphetamine-induced rotational behavior and the cell cycle distribution of dapaminergic neurons in the SNpc of these selected rats was detected. The results showed that rotenone increased the population of S phase, which may be associated with the death of postmitotic neurons.Coeloglossum. viride (L.) Hartm. var. bracteatum (Willd.) is a plant of Orchidaceae family, distributed in the Northwest of China. 4ab is one of the active component. Our results showed that 4ab inhibited the leakage of LDH from the cells and decreased the death of cells induced by rotenone. It indicates that 4ab has the neuro-protective action against rotenone in SH-SY5Y cells.