Intracellular dopamine oxidation mediates rotenone-induced apoptosis in PC12 cells.

AIM: To study the role of dopamine (DA) in rotenone-induced neurotoxicity in PC12 cells. METHODS: Cell viability was assessed by detecting the leakage of lactate dehydrogenase (LDH) into the medium. Apoptosis rate was measured by flow cytometry. Caspase-3-like activity was measured by fluorescence assay using the probe Ac-DEVD-AMC. The level of intracellular hydrogen peroxide and other peroxides in PC12 cells were quantified by loading cells with 2'-7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) in fluorescence assay. Lactic acid was measured spectrophotometrically. The DA levels in PC12 cells were determined by HPLC-ECD. RESULTS: A 48-h incubation of PC12 cells with rotenone caused an apoptotic cell death and elevated intracellular reactive oxygen species (ROS) and lactic acid accumulation. Intracellular DA depletion with reserpine significantly attenuated rotenone-induced ROS accumulation and apoptotic cell death. No change was found in rotenone-induced ROS accumulation when cells were co-treated with deprenyl. Brief treatment with reserpine at the end of rotenone treatment had no effect on rotenone-induced neurotoxicity. However, when cells were first incubated with deprenyl, a monoamine oxidase-B inhibitor for 30 min then co-incubated with rotenone plus deprenyl, a brief treatment with reserpine enhanced cell injury. CONCLUSION: Rotenone-induced apoptosis in PC12 cells was mediated by intracellular dopamine oxidation.

[Effects of extremely low frequency electromagnetic fields on DNA of testicular cells and sperm chromatin structure in mice].

OBJECTIVE: To study the effects of 50 Hz electromagnetic fields (EMFs) on DNA of testicular cells and sperm chromatin structure in mice. METHODS: Mice were exposed to 50 Hz, 0.2 mT or 6.4 mT electromagnetic fields for 4 weeks. DNA strand breakage in testicular cells was detected by single-cell gel electrophoresis assay. Sperm chromatin structure was analyzed by sperm chromatin structure assay with flow cytometry. RESULTS: After 50 Hz, 0.2 mT or 6.4 mT EMFs exposure, the percentage of cells with DNA migration in total testicular cells increased from the control level of 25.64% to 37.83% and 39.38% respectively. The relative length of comet tail and the percentage of DNA in comet tail respectively increased from the control levels of 13.06% +/- 12.38% and 1.52% +/- 3.25% to 17.86% +/- 14.60% and 2.32% +/- 4.26% after 0.2 mT exposure and to 17.88% +/- 13.71% and 2.35% +/- 3.87% after 6.4 mT exposure (P < 0.05). Exposure to EMFs had not induced significant changes in S.D.alphaT and XalphaT, but COMPalphaT (cells outside the main population of alpha t), the percentage of sperms with abnormal chromatin structure, increased in the two exposed groups. CONCLUSION: 50 Hz EMFs may have the potential to induce DNA strand breakage in testicular cells and sperm chromatin condensation in mice.

[Effects of extremely low frequency electromagnetic fields on the level of c-fos mRNA in brain and liver of mouse].

OBJECTIVE: To study the effects of extremely low frequency electromagnetic fields (ELF EMFs) on c-fos gene expression in mouse brain and liver tissues. METHODS: Mice were exposed to 50 Hz sinusoidal 0.2 mT or 6.0 mT electromagnetic field for 2 weeks or 4 weeks. Competitive RT-PCR method was used to measure c-fos mRNA level. RESULTS: After exposure to 0.2 mT or 6.0 mT field for 2 weeks, c-fos mRNA levels in brain tissue [(0.0178 +/- 0.0076) amol/120 ng cDNA and (0.0092 +/- 0.0042) amol/120 ng cDNA respectively] were higher than that of control level [(0.0012 +/- 0.0005) amol/120 ng cDNA] (P < 0.05). In liver tissue c-fos mRNA levels [(0.0117 +/- 0.0055) amol/120 ng cDNA and (0.0148 +/- 0.0162) amol/120 ng cDNA respectively] were also higher than that of control level [(0.0005 +/- 0.0005) amol/120 ng cDNA] (P < 0.05). After exposure to 0.2 mT or 6.0 mT field for 4 weeks, c-fos mRNA levels in brain tissue [(0.0100 +/- 0.0054) amol/120 ng cDNA and (0.0198 +/- 0.0079) amol/120 ng cDNA respectively] were higher than that of control level [(0.0015 +/- 0.0008) amol/120 ng cDNA] (P < 0.05). In liver tissue the exposure induced much higher expression level [(0.0173 +/- 0.0122) amol/120 ng cDNA and (0.0133 +/- 0.0090) amol/120 ng cDNA respectively] while no expression was found in the control. CONCLUSION: Exposure to 50 Hz electromagnetic fields may induce up-regulation of c-fos transcription in mouse brain and liver tissue.

[Effects of extremely low frequency electromagnetic fields on apoptosis and cell cycle of mouse brain and liver cells].

OBJECTIVE: To study the effects of extremely low frequency electromagnetic fields (ELF EMFs) on apoptosis and cell cycle of mouse brain and liver cells. METHODS: Mice were exposed to 50 Hz, 0.2 mT or 6.0 mT electromagnetic fields for 2 weeks. TUNEL and flow cytometric methods were used to analyze apoptosis and cell cycle of brain and liver cells. RESULTS: After exposure to 0.2 mT and 6.0 mT ELF EMFs for 2 weeks, apoptosis rates of brain cells [(5.60 +/- 1.47)% and (4.73 +/- 0.48)% respectively] were higher than that of control [(2.90 +/- 0.75)%], and apoptosis rates of liver cells [(4.19 +/- 2.08)% and (3.38 +/- 0.65)% respectively] were higher than that of control [(1.84 +/- 0.76)%]. G0/G1 cell percentage of brain cells [(80.21 +/- 1.68)% and (79.54 +/- 0.56)% respectively] were higher than that of control [(76.85 +/- 0.83)%], and those of liver cells [(79.42 +/- 1.80)% and (80.47 +/- 1.79)% respectively] were higher than that of control [(73.36 +/- 3.10)%]. The above differences were all statistically significant as P < 0.05. At the same time S and G2 + M cell percentage of brain and liver cells were significantly decreased. CONCLUSION: Exposure to 50 Hz EMFs may alter cell cycle and induce apoptosis of mouse brain and liver cells.

[Effects of extremely low frequency electromagnetic fields on male reproduction in mice].

OBJECTIVE: To investigate the effects of extremely low frequency electromagnetic fields (ELF EMFs) on male reproduction in mice. METHODS: 94 adult male mice were exposed to 50 Hz sinusoidal electromagnetic fields of 0.2, 3.2 or 6.4 mT for 2 weeks or 4 weeks. Testicular histology and weight, sperm amount, sperm motility and morphology were measured. The percentages of different ploidy cells and cell phases, and DNA content of testis cells were estimated by flow cytometry. The micronucleus rate of bone-marrow cell was also observed. RESULTS: The testicular weight of the mice exposed to 6.4 mT for 4 weeks [(76.06 +/- 32.25) mg] was significantly lower than that of the control [(111.44 +/- 19.99) mg, P < 0.05]; no significant histopathological changes were observed on the testis in EMFs exposed mice;the sperm amount was decreased after EMFs exposure for 4 weeks, and those of the mice exposed to 0.2 mT and 6.4 mT for 4 weeks [(4.87 +/- 0.94) x 10(6)/ml and (4.30 +/- 1.89) x 10(6)/ml respectively] were significantly lower than that of the control [(6.67 +/- 0.70) x 10(6)/ml, P < 0.05]; the rates of sperm motility also showed a decline. After 0.2, 3.2 or 6.4 mT EMFs exposure for 2 weeks, the deformity rates of sperm [(7.416 +/- 3.352)%, (6.862 +/- 2.947)% and (8.112 +/- 4.615)% respectively] were significantly higher than that of the control [(4.098 +/- 2.028)%, P < 0.01]. Similarly, those of the mice exposed for 4 weeks [(10.267 +/- 3.836)%, (11.027 +/- 7.059)%, (8.814 +/- 3.678)% respectively] were higher than that of the control [(3.714 +/- 1.830)%]. After 6.4 mT exposure for 2 weeks, the percentages of 1C testis cells [(69.56 +/- 4.07)%] was significantly lower than that of the control [(73.45 +/- 3.10)%, P < 0.05]. There were not any remarkable changes in those of 2C, 4C cells. DNA content in different ploidy cells of the mice exposed to 6.4 mT was decreased. Moreover, the cell percentage in S phase was increased significantly (P < 0.01). CONCLUSION: ELF EMFs exposure may have some adverse effects on reproduction in mice.