The Study Of Rotenone On Rats Dopaminergic Nerve And PC12 Cell Toxicity

Parkinson's disease (PD) is one of aging diseases, of which progressive degeneration of the mesencephalic dopaminergic neuron is its pathologic hallmark. Although we all know that the etiology of familial PD is related to genetic factor, the cause of many sporadic patients is still unclear. Experimental, clinical and epidemiological evidence indicates that exposure to environmental agents may contribute to the pathogenesis of PD. As a matter of fact, environmental factors have long been thought as an underlying mechanism of PD. In our study, the aim of using biochemistry assay methods, HPLC and Western blotting is to evaluate the biochemistry effects of rotenone on DA nerve system in a whole body animal exposure model. Furthermore, MTT Colorimetry, Agarose Gel Electrophoresis method and flow cytometry were also employed to investigate the toxicology characteristics and the roles of rotenone-induced apoptosis in an in vitro PC12 cell toxic model. We expected to clarify the relationship between rotenone and parkinson's disease.Our findings suggest that: 1.Rats administrated with low dose of rotenone for 20d, the content of rotenone in striatum is 3.31ng/g, and remaining 0.7 to 0.9ng/g for 4 to 8 h. 2. The semi-lethal dose of rotenone for subcutaneous injection is 3.601mg/kg, and the 95% confident limit is 2.771～4.678mg/kg. 3.Rotenone at low dose injection for 30d, 60d and 90d , it induced a remarkable decrease of the content of DA, DOPAC and HVA in rats striatum nuclei accompanied by the increase of the content of NO and the activity of NOS and caspase-3. 4.Rotenone administration causes the decrease of mitochondrial membrane potential ,the increase of cytochrome C concentration, caspase-3 activity and NO2ˉ level, and the formation of DNA ladder. L-NAME plays a protective role in the survival rate of PC12 cell induced by rotenone. From the above results it can be concluded that rotenone is a highly toxic chemical substance. It has an accumulative effect in striatum,which can consecutively damage striatum and cause the dopaminergic neuron injury. The underlying mechanism of rotenone-induced injury may be attributed to the increase of nitric oxide resulting in the collapse of mitochondrial membrane potential. The latter directly mediates the release of cytochrome C that leads to apoptosis by the way of the activation of caspase dependent pathway.