Campo magnético de frecuencia extremadamente baja: Seguridad de su aplicación a nivel del sistema nervioso central / Magnetic field of extremely low frequency: Safety of its application at the level of the central nervous system

Introducción: La enfermedad cerebrovascular constituye un importante problema de salud a nivel mundial. En la actualidad se desarrollan investigaciones científicas dedicadas al estudio de los efectos del campo magnético de frecuencia extremadamente baja para su tratamiento. No es suficientemente clara la información acerca de su inocuidad en las dosis estudiadas. Objetivo: Estudiar la seguridad de la aplicación del campo magnético de frecuencia extremadamente baja a nivel del sistema nervioso central a través de un estudio toxicológico a dosis aguda, repetida y ensayo de micronúcleos en médula ósea. Métodos: Se conformaron tres grupos experimentales con ratas Sprague Dawley Cenp:SPRD jóvenes y sanas para los experimentos de toxicidad y ratones CENP: NMRI para la evaluación mutagénica. Se utilizaron controles negativos no tratados. En el ensayo de micronúcleos se incorporó un grupo control positivo al que se administró Ciclofosfamida por vía intraperitoneal. Se aplicó un campo magnético no homogéneo con niveles de inducción magnética de 6,5 y 15 mT, tomando como referencia el valor máximo sobre la superficie de la bobina. Para la aplicación del campo magnético la bobina estimuladora se colocó sobre la cabeza asegurando la exposición completa del encéfalo. Resultados: En ninguno de los ensayos se detectaron signos de toxicidad. Se comprobó así mismo que no se indujeron efectos genotóxicos ni citotóxicos sobre las células somáticas. Conclusiones: El tratamiento con campo magnético de frecuencia extremadamente baja a nivel del sistema nervioso central en las condiciones experimentales y dosis estudiadas es seguro(AU)

Introduction: Stroke is a major health problem all over the world. Nowadays are developed scientific researches devoted to the study of extremely low frequency magnetic field effects over this illness. The information about it safety is unclear yet. Objective: To study the safety of extremely low frequency magnetic field applied at central nervous system level wasby means ofa toxicological assay (Acute, repeated doses and micronucleus in bone marrow assay) Methods: Three experimental groups were made with Sprague Dawley Cenp: SPRD young and healthy rats for toxicity experiments and CENP: NMRI mice for mutagen evaluation. Untreated negative controls were used. In the micronucleus assay, an additional positive control group was included. This group received Cyclophosphamide by intraperitoneal administration. Was applied a non-homogenousmagnetic fieldof 6,5 and 15 mT, taken as reference the maximum value over the coil surface. The coil was positioned over the head, ensuring full exposure of brain to magnetic field. Results : In none of trials were detected any sign of toxicity. It was also found no genotoxic or cytotoxic effects induced on somatic cells. Conclusions : These results indicated the safety of treatmentwith extremely low frequency magnetic field at central nervous system level for experimental conditions and doses studied(AU)

Extremely Low Frequency Magnetic Field Modulates the Level of Neurotransmitters

This study was aimed to observe that extremely low frequency magnetic field (ELF-MF) may be relevant to changes of major neurotransmitters in rat brain. After the exposure to ELF-MF (60 Hz, 2.0 mT) for 2 or 5 days, we measured the levels of biogenic amines and their metabolites, amino acid neurotransmitters and nitric oxide (NO) in the cortex, striatum, thalamus, cerebellum and hippocampus. The exposure of ELF-MF for 2 or 5 days produced significant differences in norepinephrine and vanillyl mandelic acid in the striatum, thalamus, cerebellum and hippocampus. Significant increases in the levels of serotonin and 5-hydroxyindoleacetic acid were also observed in the striatum, thalamus or hippocampus. ELF-MF significantly increased the concentration of dopamine in the thalamus. ELF-MF tended to increase the levels of amino acid neurotransmitters such as glutamine, glycine and gamma -aminobutyric acid in the striatum and thalamus, whereas it decreased the levels in the cortex, cerebellum and hippocampus. ELF-MF significantly increased NO concentration in the striatum, thalamus and hippocampus. The present study has demonstrated that exposure to ELF-MFs may evoke the changes in the levels of biogenic amines, amino acid and NO in the brain although the extent and property vary with the brain areas. However, the mechanisms remain further to be characterized.

Combined effects of 50 Hz magnetic field and magnetic nanoparticles on the proliferation and apoptosis of PC12 cells / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the bioeffects of extremely low frequency (ELF) magnetic field (MF) (50 Hz, 400 μT) and magnetic nanoparticles (MNPs) via cytotoxicity and apoptosis assays on PC12 cells.</p><p><b>METHODS</b>MNPs modified by SiO₂ (MNP-SiO₂) were characterized by transmission electron microscopy (TEM), dynamic light scattering and hysteresis loop measurement. PC12 cells were administrated with MNP-SiO2 with or without MF exposure for 48 h. Cytotoxicity and apoptosis were evaluated with MTT assay and annexin V-FITC/PI staining, respectively. The morphology and uptake of MNP-SiO₂ were determined by TEM. MF simulation was performed by Ansoft Maxwell based on the finite element method.</p><p><b>RESULTS</b>MNP-SiO₂ were identified as ~20 nm (diameter) ferromagnetic particles. MNP-SiO₂ reduced cell viability in a dose-dependent manner. MF also reduced cell viability with increasing concentrations of MNP-SiO₂. MNP-SiO₂ alone did not cause apoptosis in PC12 cells; instead, the proportion of apoptotic cells increased significantly under MF exposure and increasing doses of MNP-SiO₂. MNP-SiO₂ could be ingested and then cause a slight change in cell morphology.</p><p><b>CONCLUSION</b>Combined exposure of MF and MNP-SiO₂ resulted in remarkable cytotoxicity and increased apoptosis in PC12 cells. The results suggested that MF exposure could strengthen the MF of MNPs, which may enhance the bioeffects of ELF MF.</p>

Low Frequency magnetic field induces depression by rising nitric oxide levels in the mouse brain.

The present study was designed to investigate the influence of Extremely low frequency magnetic field (ELF MF) on depression related behavior, and mechanism involved therein. Mice were exposed to ELF MF (50Hz, 10G) 8h/day for 7, 30, 60, 90 and 120 days. Depression was assessed using forced swim test (FST), in which no significant effect was observed on 7t h, 30t h, 60t h, 90t h exposure day. However, depression was observed on 120t h exposure day. It is evident that ELF MF exposure modulates level of nitric oxide (NO); therefore, the level of NO was measured in the regions of brain viz; cortex, striatum, hippocampus and hypothalamus. Results established that ELF MF elevated NO levels in the regions of brain. Furthermore, the implication of NO was assessed by nitric oxide synthase (NOS) inhibitors suggesting the involvement of NO in ELF MF induced depression.

Effects of Extremely Low Frequency Elecromagnetic Fields on Thyroid Carcinogenesis Induced by N-bis(2-hydroxypropyl)nitrosamine and Sulfadimethoxine

PURPOSE: Long-term exposure to extremely low-frequency (60 Hz) electromagnetic fields (ELF-EMF) raises the questions of the induction of biological effects including tumorigenesis. One mechanism through which ELF-MFS could influence neoplastic development is the imbalance of cellular proliferation and cell apoptosis. The present study investigated the effect of ELF-EMF on chemically-induced thyroid carcinogenesis in a rat. METHODS: We examined cellular proliferation index measured by anti-Ki-67 antigen, apoptosis, apoptosis related proteins such as caspase 3 and p53, and cell cycle-related proteins (cyclin D1 and p21(WAF1/Cip1)). Forty Male F344 rats received a subcutaneous N-bis(2-hydroxypropyl)nitrosamine (DHPN, 2,800 mg/kg) injection, and 1 week later were allowed free access to drinking water containing sulfadimethoxine (0.1%) for 12 weeks. Twenty rats were exposed by ELF-EMF. During the carcinogenesis, sequential histological changes from hyperplasia, adenoma, and ultimately to overt carcinomas were noted. RESULTS: The exposure group of ELF-EMF, significantly increases the number size of carcinomas. Also, the proliferative and apoptotic indices were significantly increased in the ELF-EMF exposure group than in the control group. The caspase 3 protein expression did not show any significant changes between ELF-EMF group and control group. The p53 protein was not detected in both ELF-EMF exposure and control group. Among the cell cycle related proteins, cyclin D1, not p21(WAF1/Cip1), was significantly increased in adenomas and carcinomas in ELF-EMF exposure group compared with the control group. CONCLUSION: Exposure of ELF-EMF effects on chemically-induced rat thyroid carcinogenesis as results of altered increase of cellular proliferation, apoptosis, and cyclin D1 expression.