Microwave Radiation Caused Dynamic Metabolic Fluctuations in the Mammalian Hippocampus.

To investigate the dynamic changes in hippocampal metabolism after microwave radiation using liquid chromatography in tandem with mass spectrometry/mass spectrometry (LC-MS/MS) and to identify potential biomarkers. Wistar rats were randomly assigned to a sham group and a microwave radiation group. The rats in the microwave radiation group were exposed to 2.856 GHz for 15 min for three times, with 5 min intervals. The rats in the sham group were not exposed. Transmission electron microscope revealed blurring of the synaptic cleft and postsynaptic dense thickening in hippocampal neurons after microwave radiation. Metabolomic analysis revealed 38, 24, and 39 differentially abundant metabolites at 3, 7, and 14 days after radiation, respectively, and the abundance of 9 metabolites, such as argininosuccinic acid, was continuously decreased. After microwave radiation, the abundance of metabolites such as argininosuccinic acid was successively decreased, indicating that these metabolites could be potential biomarkers for hippocampal tissue injury.

Establishment of injury models in studies of biological effects induced by microwave radiation.

Microwave radiation has been widely used in various fields, such as communication, industry, medical treatment, and military applications. Microwave radiation may cause injuries to both the structures and functions of various organs, such as the brain, heart, reproductive organs, and endocrine organs, which endanger human health. Therefore, it is both theoretically and clinically important to conduct studies on the biological effects induced by microwave radiation. The successful establishment of injury models is of great importance to the reliability and reproducibility of these studies. In this article, we review the microwave exposure conditions, subjects used to establish injury models, the methods used for the assessment of the injuries, and the indicators implemented to evaluate the success of injury model establishment in studies on biological effects induced by microwave radiation.

Dose-dependent Cardiac Dysfunction and Structural Damage in Rats after Shortwave Radiation.

OBJECTIVE: To detect the effects of shortwave radiation on dose-dependent cardiac structure and function in rats after radiation and to elucidate the mechanism of shortwave radiation induced cardiac injury to identify sensitive indicators and prophylactic treatment. METHODS: One hundred Wistar rats were either exposed to 27 MHz continuous shortwave at a power density of 5, 10, and 30 mW/cm 2 for 6 min or undergone sham exposure for the control (the rats had to be placed in the exposure system with the same schedules as the exposed animals, but with an inactive antenna). The Ca 2+, glutamic oxaloacetic transaminase (AST), creatine kinase (CK) and lactate dehydrogenase (LDH) content in the peripheral serum of the rats were detected by an automatic blood biochemical analyser. The electrocardiogram (ECG) of standard lead II was recorded by a multi-channel physiological recording and analysis system. The cardiac structure of rats was observed by light and electron microscopy. RESULTS: The results showed that the 5, 10, and 30 mW/cm 2 shortwave radiation caused a significant increased in the levels of Ca 2+, AST, CK, and LDH in the peripheral serum of rats. The cardiac structure was damaged by radiation and showed a disordered arrangement of myocardial fibres, the cavitation and swelling of myocardial mitochondria. These injuries were most significant 7 d after radiation and were not restored until 28 d after radiation. CONCLUSION: Shortwave radiation of 5, 10, and 30 mW/cm 2 can damage rat cardiac function, including damage to the tissue structure and ultrastructure, especially at the level of the myocardial fibres and mitochondria. Shortwave radiation at 5, 10, and 30 mW/cm 2 induced damage to rat heart function and structure with a dose-effect relationship, i.e., the greater the radiation dose was, the more significant the damage was.

Exposure Effects of Terahertz Waves on Primary Neurons and Neuron-like Cells Under Nonthermal Conditions.

OBJECTIVE: This study aimed to explore the potential effects of terahertz (THz) waves on primary cultured neurons from 4 rat brain regions (hippocampus, cerebral cortex, cerebellum, and brainstem) and 3 kinds of neuron-like cells (MN9D, PC12, and HT22 cells) under nonthermal conditions. METHODS: THz waves with an output power of 50 (0.16 THz) and 10 (0.17 THz) mW with exposure times of 6 and 60 min were used in this study. Analysis of temperature change, neurite growth, cell membrane roughness, micromorphology, neurotransmitters and synaptic-related proteins (SYN and PSD95) was used to evaluate the potential effects. RESULTS: Temperature increase caused by the THz wave was negligible. THz waves induced significant neurotransmitter changes in primary hippocampal, cerebellar, and brainstem neurons and in MN9D and PC12 cells. THz wave downregulated SYN expression in primary hippocampal neurons and downregulated PSD95 expression in primary cortical neurons. CONCLUSION: Different types of cells responded differently after THz wave exposure, and primary hippocampal and cortical neurons and MN9D cells were relatively sensitive to the THz waves. The biological effects were positively correlated with the exposure time of the THz waves.

A novel microcurrent dressing for wound healing in a rat skin defect model.

BACKGROUND: The exogenous application of low-intensity electric stimulation (ES) may mimic a natural endogenous bioelectric current and accelerate the repair process of skin wounds. This study designed a novel microcurrent dressing (MCD) and evaluated its potential effects on wound healing in a rat skin defect model. METHODS: First, wireless ES was integrated into a medical cotton cushion to fabricate the MCD, and its electrical property was examined by using a universal power meter. Then, animal experiments were conducted to evaluate the MCD's effect. Forty-five rats were randomized into control (Con) group, Vaseline gauze (VG) group and MCD group. A full-thickness round skin incision 1.5 cm in diameter was made on the back of each animal. Apart from routine disinfection, the Con rats were untreated, whereas the other two groups were treated with VG or MCD. On days 3, 7 and 14 post injury, the wound areas were observed and measured using image analysis software following photography, and the skin samples were harvested from wound tissue. Then, histopathological morphology was observed routinely by hematoxylin and eosin (HE) staining; tumor necrosis factor α (TNF-α) and interleukin (IL)-1ß expression were detected by Western blotting. Vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF) expression were detected with immunohistochemistry. RESULTS: The MCD generated a sf electric potential greater than 0.95 V. Animal experiments showed that the wound-healing rate in the MCD group was significantly increased compared with the Con and VG groups (P < 0.05 or P < 0.01). Histopathological observation revealed an alleviated inflammatory response, induced vascular proliferation and accelerated epithelization in the MCD group. Moreover, samples from the MCD group expressed reduced TNF-α and IL-1ß levels and increased VEGF and EGF levels compared with those of the other two groups (P < 0.05 or P < 0.01). However, no significant difference was noted between the Con and VG groups at each time point. CONCLUSIONS: The MCD generates a stable and lasting ES and significantly promotes wound healing by reducing inflammation duration and increasing growth factors expression. Thus, MCD may act as a promising biomaterial device for skin wound healing.

Microwave radiation leading to shrinkage of dendritic spines in hippocampal neurons mediated by SNK-SPAR pathway.

The popularization of microwave raised concerns about its influence on health including cognitive function which is associated greatly with dendritic spines plasticity. SNK-SPAR is a molecular pathway for neuronal homeostatic plasticity during chronically elevated activity. In this study, Wistar rats were exposed to microwaves (30 mW/cm2 for 6 min, 3 times/week for 6 weeks). Spatial learning and memory function, distribution of dendritic spines, ultrastructure of the neurons and their dendritic spines in hippocampus as well as the related critical molecules of SNK-SPAR pathway were examined at different time points after microwave exposure. There was deficiency in spatial learning and memory in rats, loss of spines in granule cells and shrinkage of mature spines in pyramidal cells, accompanied with alteration of ultrastructure of hippocampus neurons. After exposure to 30 mW/cm2 microwave radiation, the up-regulated SNK induced decrease of SPAR and PSD-95, which was thought to cause the changes mentioned above. In conclusion, the microwave radiation led to shrinkage and even loss of dendritic spines in hippocampus by SNK-SPAR pathway, resulting in the cognitive impairments.

Biological effects and mechanisms of shortwave radiation: a review.

With the increasing knowledge of shortwave radiation, it is widely used in wireless communications, radar observations, industrial manufacturing, and medical treatments. Despite of the benefits from shortwave, these wide applications expose humans to the risk of shortwave electromagnetic radiation, which is alleged to cause potential damage to biological systems. This review focused on the exposure to shortwave electromagnetic radiation, considering in vitro, in vivo and epidemiological results that have provided insight into the biological effects and mechanisms of shortwave. Additionally, some protective measures and suggestions are discussed here in the hope of obtaining more benefits from shortwave with fewer health risks.

Apoptosis of Lewis Lung Carcinoma Cells Induced by Microwave via p53 and Proapoptotic Proteins In vivo.

BACKGROUND: Microwave therapy is a minimal invasive procedure and has been employed in clinical practice for the treatment of various types of cancers. However, its therapeutic application in non-small-cell lung cancer and the underlying mechanism remains to be investigated. This study aimed to investigate its effect on Lewis lung carcinoma (LLC) tumor in vivo. METHODS: Fifty LLC tumor-bearing C57BL/6 mice were adopted to assess the effect of microwave radiation on the growth and apoptosis of LLC tumor in vivo. These mice were randomly assigned to 10 groups with 5 mice in each group. Five groups were treated by single pulse microwave at different doses for different time, and the other five groups were radiated by multiple-pulse treatment of a single dose. Apoptosis of cancer cells was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. Western blotting was applied to detect the expression of proteins. RESULTS: Single pulse of microwave radiation for 5 min had little effect on the mice. Only 15-min microwave radiation at 30 mW/cm2 significantly increased the mice body temperature (2.20 ± 0.82)°C as compared with the other groups (0.78 ± 0.29 °C, 1.24 ± 0.52 °C, 0.78 ± 0.42 °C, respectively), but it did not affect the apoptosis of LLC tumor cells significantly. Continous microwave radiation exposure, single dose microwave radiation once per day for up to seven days, inhibited cell division and induced apoptosis of LLC tumor cells in a dose- and duration-dependent manner. It upregulated the protein levels of p53, Caspase 3, Bax and downregulated Bcl-2 protein. CONCLUSIONS: Multiple exposures of LLC-bearing mice to microwave radiation effectively induced tumor cell apoptosis at least partly by upregulating proapoptotic proteins and downregulating antiapoptotic proteins. Continuous radiation at low microwave intensity for a short time per day is promising in treating non-small-cell lung cancer.

Real-time Assessment of Cytosolic, Mitochondrial, and Nuclear Calcium Levels Change in Rat Pheochromocytoma Cells during Pulsed Microwave Exposure Using a Genetically Encoded Calcium Indicator.

Little information is available about the effects of exposure to pulsed microwaves on neuronal Ca2+ signaling under non-thermal conditions. In this study, rat pheochromocytoma (PC12) cells were exposed to pulsed microwaves for 6 min at a specific absorption rate (SAR) of 4 W/kg to assess possible real-time effects. During microwave exposure, free calcium dynamics in the cytosol, mitochondria, and nucleus of cells were monitored by time-lapse microfluorimetry using a genetically encoded calcium indicator (ratiometric-pericam, ratiometric-pericam-mt, and ratiometric-pericam-nu). We established a waveguide-based real-time microwave exposure system under accurately controlled environmental and dosimetric conditions and found no significant changes in the cytosolic, mitochondrial, or nuclear calcium levels in PC12 cells. These findings suggest that no dynamic changes occurred in [Ca2+]c, [Ca2+]m, or [Ca2+]n of PC12 cells at the non-thermal level.

Basic roles of key molecules connected with NMDAR signaling pathway on regulating learning and memory and synaptic plasticity.

With key roles in essential brain functions ranging from the long-term potentiation (LTP) to synaptic plasticity, the N-methyl-D-aspartic acid receptor (NMDAR) can be considered as one of the fundamental glutamate receptors in the central nervous system. The role of NMDA R was first identified in synaptic plasticity and has been extensively studied. Some molecules, such as Ca(2+), postsynaptic density 95 (PSD-95), calcium/calmodulin-dependent protein kinase II (CaMK II), protein kinase A (PKA), mitogen-activated protein kinase (MAPK) and cyclic adenosine monophosphate (cAMP) responsive element binding protein (CREB), are of special importance in learning and memory. This review mainly focused on the new research of key molecules connected with learning and memory, which played important roles in the NMDAR signaling pathway.

Identification of a Novel Rat NR2B Subunit Gene Promoter Region Variant and Its Association with Microwave-Induced Neuron Impairment.

Microwave radiation has been implicated in cognitive dysfunction and neuronal injury in animal models and in human investigations; however, the mechanism of these effects is unclear. In this study, single nucleotide polymorphism (SNP) sites in the rat GRIN2B promoter region were screened. The associations of these SNPs with microwave-induced rat brain dysfunction and with rat pheochromocytoma-12 (PC12) cell function were investigated. Wistar rats (n = 160) were exposed to microwave radiation (30 mW/cm(2) for 5 min/day, 5 days/week, over a period of 2 months). Screening of the GRIN2B promoter region revealed a stable C-to-T variant at nucleotide position -217 that was not induced by microwave exposure. The learning and memory ability, amino acid contents in the hippocampus and cerebrospinal fluid, and NR2B expression were then investigated in the different genotypes. Following microwave exposure, NR2B protein expression decreased, while the Glu contents in the hippocampus and CSF increased, and memory impairment was observed in the TT genotype but not the CC and CT genotypes. In PC12 cells, the effects of the T allele were more pronounced than those of the C allele on transcription factor binding ability, transcriptional activity, NR2B mRNA, and protein expression. These effects may be related to the detrimental role of the T allele and the protective role of the C allele in rat brain function and PC12 cells exposed to microwave radiation.

Heijiangdan ointment relieves oxidative stress from radiation dermatitis induced by (60)Co γ-ray in mice.

OBJECTIVE: To investigate the effects of Heijiangdan Ointment ( HJD) on oxidative stress in (60)Co γ-ray radiation-induced dermatitis in mice. METHODS: Female Wistar mice with grade 4 radiation dermatitis induced by (60)Co γ-rays were randomly divided into four groups (n=12 per group); the HJD-treated, recombinant human epidermal growth factor (rhEGF)-treated, Trolox-treated, and untreated groups, along with a negative control group. On the 11th and 21st days after treatment, 6 mice in each group were chosen for evaluation. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), and lactate dehydrogenase (LDH) were detected using spectrophotometric methods. The fibroblast mitochondria were observed by transmission electron microscopy (TEM). The expressions of fibroblast growth factor 2 (FGF-2) and transforming growth factor ß1 (TGF-ß1) were analyzed by western blot. RESULTS: Compared with the untreated group, the levels of SOD, MDA and LDH, on the 11th and 21st days after treatment showed significant difference (P<0.05). TEM analysis indicated that fibroblast mitochondria in the untreated group exhibited swelling and the cristae appeared fractured, while in the HJD group, the swelling of mitochondria was limited and the rough endoplasmic reticulum appeared more relaxed. The expressions of FGF-2 and TGF-ß1 increased in the untreated group compared with the negative control group (P<0.05). After treatment, the expression of FGF-2, rhEGF and Trolox in the HJD group were significantly increased compared with the untreated group (P<0.05), or compared with the negative control group (P<0.05). The expression of TGF-ß1 showed significant difference between untreated and negative control groups (P<0.05). HJD and Trolox increased the level of TGF-ß1 and the difference was marked as compared with the untreated and negative control groups (P<0.05). CONCLUSION: HJD relieves oxidative stress-induced injury, increases the antioxidant activity, mitigates the fibroblast mitochondrial damage, up-regulates the expression of growth factor, and promotes mitochondrial repair in mice.

Microwave-Induced Structural and Functional Injury of Hippocampal and PC12 Cells Is Accompanied by Abnormal Changes in the NMDAR-PSD95-CaMKII Pathway.

Recent studies have highlighted the important role of the postsynaptic NMDAR-PSD95-CaMKII pathway for synaptic transmission and related neuronal injury. Here, we tested changes in the components of this pathway upon microwave-induced neuronal structure and function impairments. Ultrastructural and functional changes were induced in hippocampal neurons of rats and in PC12 cells exposed to microwave radiation. We detected abnormal protein and mRNA expression, as well as posttranslational modifications in the NMDAR-PSD95-CaMKII pathway and its associated components, such as synapsin I, following microwave radiation exposure of rats and PC12 cells. Thus, microwave radiation may induce neuronal injury via changes in the molecular organization of postsynaptic density and modulation of the biochemical cascade that potentiates synaptic transmission.

Effects of microwave radiation on brain energy metabolism and related mechanisms.

With the rapid development of electronic technologies, anxiety regarding the potential health hazards induced by microwave radiation (MW) has been growing in recent years. The brain is one of the most sensitive target organs for microwave radiation, where mitochondrial injury occurs earlier and more severely than in other organs. Energy metabolism disorders do play an important role during the process of microwave radiation-induced brain damage. In this paper, we will review the biological effects of microwave radiation, the features of brain energy supply and consumption and the effects of microwave radiation on mitochondrial energy metabolism and potential related mechanisms.

Protecting intestinal epithelial cell number 6 against fission neutron irradiation through NF-κB signaling pathway.

The purpose of this paper is to explore the change of NF-κB signaling pathway in intestinal epithelial cell induced by fission neutron irradiation and the influence of the PI3K/Akt pathway inhibitor LY294002. Three groups of IEC-6 cell lines were given: control group, neutron irradiation of 4 Gy group, and neutron irradiation of 4 Gy with LY294002 treatment group. Except the control group, the other groups were irradiated by neutron of 4 Gy. LY294002 was given before 24 hours of neutron irradiation. At 6 h and 24 h after neutron irradiation, the morphologic changes, proliferation ability, apoptosis, and necrosis rates of the IEC-6 cell lines were assayed and the changes of NF-κB and PI3K/Akt pathway were detected. At 6 h and 24 h after neutron irradiation of 4 Gy, the proliferation ability of the IEC-6 cells decreased and lots of apoptotic and necrotic cells were found. The injuries in LY294002 treatment and neutron irradiation group were more serious than those in control and neutron irradiation groups. The results suggest that IEC-6 cells were obviously damaged and induced serious apoptosis and necrosis by neutron irradiation of 4Gy; the NF-κB signaling pathway in IEC-6 was activated by neutron irradiation which could protect IEC-6 against injury by neutron irradiation; LY294002 could inhibit the activity of IEC-6 cells.

Microwave exposure impairs synaptic plasticity in the rat hippocampus and PC12 cells through over-activation of the NMDA receptor signaling pathway.

OBJECTIVE: The aim of this study is to investigate whether microwave exposure would affect the N-methyl-D-aspartate receptor (NMDAR) signaling pathway to establish whether this plays a role in synaptic plasticity impairment. METHODS: 48 male Wistar rats were exposed to 30 mW/cm2 microwave for 10 min every other day for three times. Hippocampal structure was observed through H&E staining and transmission electron microscope. PC12 cells were exposed to 30 mW/cm2 microwave for 5 min and the synapse morphology was visualized with scanning electron microscope and atomic force microscope. The release of amino acid neurotransmitters and calcium influx were detected. The expressions of several key NMDAR signaling molecules were evaluated. RESULTS: Microwave exposure caused injury in rat hippocampal structure and PC12 cells, especially the structure and quantity of synapses. The ratio of glutamic acid and gamma-aminobutyric acid neurotransmitters was increased and the intracellular calcium level was elevated in PC12 cells. A significant change in NMDAR subunits (NR1, NR2A, and NR2B) and related signaling molecules (Ca2+/calmodulin-dependent kinase II gamma and phosphorylated cAMP-response element binding protein) were examined. CONCLUSION: 30 mW/cm2 microwave exposure resulted in alterations of synaptic structure, amino acid neurotransmitter release and calcium influx. NMDAR signaling molecules were closely associated with impaired synaptic plasticity.

Activation of VEGF/Flk-1-ERK Pathway Induced Blood-Brain Barrier Injury After Microwave Exposure.

Microwaves have been suggested to induce neuronal injury and increase permeability of the blood-brain barrier (BBB), but the mechanism remains unknown. The role of the vascular endothelial growth factor (VEGF)/Flk-1-Raf/MAPK kinase (MEK)/extracellular-regulated protein kinase (ERK) pathway in structural and functional injury of the blood-brain barrier (BBB) following microwave exposure was examined. An in vitro BBB model composed of the ECV304 cell line and primary rat cerebral astrocytes was exposed to microwave radiation (50 mW/cm(2), 5 min). The structure was observed by scanning electron microscopy (SEM) and the permeability was assessed by measuring transendothelial electrical resistance (TEER) and horseradish peroxidase (HRP) transmission. Activity and expression of VEGF/Flk-1-ERK pathway components and occludin also were examined. Our results showed that microwave radiation caused intercellular tight junctions to broaden and fracture with decreased TEER values and increased HRP permeability. After microwave exposure, activation of the VEGF/Flk-1-ERK pathway and Tyr phosphorylation of occludin were observed, along with down-regulated expression and interaction of occludin with zonula occludens-1 (ZO-1). After Flk-1 (SU5416) and MEK1/2 (U0126) inhibitors were used, the structure and function of the BBB were recovered. The increase in expression of ERK signal transduction molecules was muted, while the expression and the activity of occludin were accelerated, as well as the interactions of occludin with p-ERK and ZO-1 following microwave radiation. Thus, microwave radiation may induce BBB damage by activating the VEGF/Flk-1-ERK pathway, enhancing Tyr phosphorylation of occludin, while partially inhibiting expression and interaction of occludin with ZO-1.

[Microwave radiation induces injury to GC-2spd cells].

OBJECTIVE: To explore the impact of microwave radiation on GC-2spd cells. METHODS: We exposed cultured GC-2spd cells to microwave radiation at the average power densities of 0, 10 and 30 mW/cm2 for 15 minutes and, from I to 24 hours after the exposure, we observed the changes in cell proliferation, histology and ultrastructure, cell apoptosis, and cAMP content by MTIT, light microscopy, electron microscopy, flow cytometry and ELISA. RESULTS: Compared with the control group, the GC-2spd cells showed a significant decrease in proliferation ability at 1 -24 hours after 10 and 30 mW/cm2 microwave radiation, except at 12 hours after 30 mW/cm2 radiation (P <0.05 or P <0.01), with reduced length and number of cell enation and increased intra cytoplasm vacuoles. The rate of cell apoptosis (%) was significantly increased in the 10 and 30 mW/cm2 groups at 6 hours (4.56 +/- 2.09 vs 14.59 +/- 1.09 and 8.48 +/- 1.73, P <0.05 or P <0.01) , with agglutination and margin translocation of chromatins and obvious dilation of endo cytoplasmic reticula. The cAMP content (nmol/g) in the GC-2spd cells was remarkably reduced in the 10 and 30 mW/cm2 groups at 6 and 24 hours (2.77 +/-0.24 vs 1.65+/- 0. 17 and 1.96+/-0.10, 3.02 +/-0.47 vs 2.13 +/-0.33 and 1.69 +/-0.27, P <0.05 or P <0.01). CONCLUSION: Microwave radiation at 10 and 30 mW/cm2 may cause injury to GC-2spd cells, which is manifested by decreased content of intracellular cAMP, reduced activity of cell proliferation, and increased rate of cell apoptosis.