Radiofrequency radiation reshapes tumor immune microenvironment into antitumor phenotype in pulmonary metastatic melanoma by inducing active transformation of tumor-infiltrating CD8+ T and NK cells.

Immunosuppression by the tumor microenvironment is a pivotal factor contributing to tumor progression and immunotherapy resistance. Priming the tumor immune microenvironment (TIME) has emerged as a promising strategy for improving the efficacy of cancer immunotherapy. In this study we investigated the effects of noninvasive radiofrequency radiation (RFR) exposure on tumor progression and TIME phenotype, as well as the antitumor potential of PD-1 blockage in a model of pulmonary metastatic melanoma (PMM). Mouse model of PMM was established by tail vein injection of B16F10 cells. From day 3 after injection, the mice were exposed to RFR at an average specific absorption rate of 9.7 W/kg for 1 h per day for 14 days. After RFR exposure, lung tissues were harvested and RNAs were extracted for transcriptome sequencing; PMM-infiltrating immune cells were isolated for single-cell RNA-seq analysis. We showed that RFR exposure significantly impeded PMM progression accompanied by remodeled TIME of PMM via altering the proportion and transcription profile of tumor-infiltrating immune cells. RFR exposure increased the activation and cytotoxicity signatures of tumor-infiltrating CD8+ T cells, particularly in the early activation subset with upregulated genes associated with T cell cytotoxicity. The PD-1 checkpoint pathway was upregulated by RFR exposure in CD8+ T cells. RFR exposure also augmented NK cell subsets with increased cytotoxic characteristics in PMM. RFR exposure enhanced the effector function of tumor-infiltrating CD8+ T cells and NK cells, evidenced by increased expression of cytotoxic molecules. RFR-induced inhibition of PMM growth was mediated by RFR-activated CD8+ T cells and NK cells. We conclude that noninvasive RFR exposure induces antitumor remodeling of the TIME, leading to inhibition of tumor progression, which provides a promising novel strategy for TIME priming and potential combination with cancer immunotherapy.

Chromosome-level genome of Entada phaseoloides provides insights into genome evolution and biosynthesis of triterpenoid saponins.

As a medicinal herbal plant, Entada phaseoloides has high levels of secondary metabolites, particularly triterpenoid saponins, which are important resources for scientific research and medical applications. However, the lack of a reference genome for this genus has limited research on its evolution and utilization of its medicinal potential. In this study, we report a chromosome-scale genome assembly for E. phaseoloides using Illumina, Nanopore long reads and high-throughput chromosome conformation capture technology. The assembled reference genome is 456.18 Mb (scaffold N50 = 30.9 Mb; contig N50 = 6.34 Mb) with 95.71% of the sequences anchored onto 14 pseudochromosomes. E. phaseoloides was estimated to have diverged from the Leguminosae lineage at ~72.0 million years ago. With the integration of transcriptomic and metabolomic data, gene expression patterns and metabolite profiling of E. phaseoloides were determined in different tissues. The pattern of gene expression and metabolic profile of the kernel were distinct from those of other tissues. Furthermore, the evolution of certain gene families involved in the biosynthesis of triterpenoid saponins and terpenes was analysed and offers new insights into the formation of these two metabolites. Four CYP genes, one UGT gene and related transcription factors were identified as candidate genes contributing to regulation of triterpenoid saponin biosynthesis. As the first high-quality assembled reference genome in the genus Entada, it will not only provide new information for the evolutionary study of this genus and conservation biology of E. phaseoloides but also lay a foundation for the formation and utilization of secondary metabolites in medicinal plants.

Long read sequencing of Toona sinensis (A. Juss) Roem: A chromosome-level reference genome for the family Meliaceae.

Chinese mahogany (Toona sinensis) is a woody plant that is widely cultivated in China and Malaysia. Toona sinensis is important economically, including as a nutritious food source, as material for traditional Chinese medicine and as a high-quality hardwood. However, the absence of a reference genome has hindered in-depth molecular and evolutionary studies of this plant. In this study, we report a high-quality T. sinensis genome assembly, with scaffolds anchored to 28 chromosomes and a total assembled length of 596 Mb (contig N50 = 1.5 Mb and scaffold N50 = 21.5 Mb). A total of 34,345 genes were predicted in the genome after homology-based and de novo annotation analyses. Evolutionary analysis showed that the genomes of T. sinensis and Populus trichocarpa diverged ~99.1-103.1 million years ago, and the T. sinensis genome underwent a recent genome-wide duplication event at ~7.8 million years and one more ancient whole genome duplication event at ~71.5 million years. These results provide a high-quality chromosome-level reference genome for T. sinensis and confirm its evolutionary position at the genomic level. Such information will offer genomic resources to study the molecular mechanism of terpenoid biosynthesis and the formation of flavour compounds, which will further facilitate its molecular breeding. As the first chromosome-level genome assembled in the family Meliaceae, it will provide unique insights into the evolution of members of the Meliaceae.

Synergic Effects of Berberine and Curcumin on Improving Cognitive Function in an Alzheimer's Disease Mouse Model.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, and no effective therapies have been found to prevent or cure AD to date. Berberine and curcumin are extracts from traditional Chinese herbs that have a long history of clinical benefits for AD. Here, using a transgenic AD mouse model, we found that the combined berberine and curcumin treatment had a much better effect on improving the cognitive function of mice than the single-drug treatment, suggesting synergic effects of the combined berberine and curcumin treatment. In addition, we found that the combined berberine and curcumin treatment had significant synergic effects on reducing soluble amyloid-ß-peptide(1-42) production. Furthermore, the combination treatment also had remarkable synergic effects on decreasing inflammatory responses and oxidative stress in both the cortex and hippocampus of AD mice. We also found that the combination treatment performed much better than the single drugs in reducing the APP and BACE1 levels and increasing AMPKα phosphorylation and cell autophagy, which might be the underlying mechanism of the synergic effects. Taken together, the result of this study reveal the synergic effects and potential underlying mechanisms of the combined berberine and curcumin treatment in improving the symptoms of AD in mice. This study sheds light on a new strategy for exploring new phytotherapies for AD and also emphasizes that more research should focus on the synergic effects of herbal drugs in the future.

Inhibition of STAT3- and MAPK-dependent PGE2 synthesis ameliorates phagocytosis of fibrillar ß-amyloid peptide (1-42) via EP2 receptor in EMF-stimulated N9 microglial cells.

BACKGROUND: Prostaglandin E2 (PGE2)-involved neuroinflammatory processes are prevalent in several neurological conditions and diseases. Amyloid burden is correlated with the activation of E-prostanoid (EP) 2 receptors by PGE2 in Alzheimer's disease. We previously demonstrated that electromagnetic field (EMF) exposure can induce pro-inflammatory responses and the depression of phagocytosis in microglial cells, but the signaling pathways involved in phagocytosis of fibrillar ß-amyloid (fAß) in microglial cells exposed to EMF are poorly understood. Given the important role of PGE2 in neural physiopathological processes, we investigated the PGE2-related signaling mechanism in the immunomodulatory phagocytosis of EMF-stimulated N9 microglial cells (N9 cells). METHODS: N9 cells were exposed to EMF with or without pretreatment with the selective inhibitors of cyclooxygenase-2 (COX-2), Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinases (MAPKs) and antagonists of PG receptors EP1-4. The production of endogenous PGE2 was quantified by enzyme immunoassays. The phagocytic ability of N9 cells was evaluated based on the fluorescence intensity of the engulfed fluorescent-labeled fibrillar ß-amyloid peptide (1-42) (fAß42) measured using a flow cytometer and a fluorescence microscope. The effects of pharmacological agents on EMF-activated microglia were investigated based on the expressions of JAK2, STAT3, p38/ERK/JNK MAPKs, COX-2, microsomal prostaglandin E synthase-1 (mPGES-1), and EP2 using real-time PCR and/or western blotting. RESULTS: EMF exposure significantly increased the production of PGE2 and decreased the phagocytosis of fluorescent-labeled fAß42 by N9 cells. The selective inhibitors of COX-2, JAK2, STAT3, and MAPKs clearly depressed PGE2 release and ameliorated microglial phagocytosis after EMF exposure. Pharmacological agents suppressed the phosphorylation of JAK2-STAT3 and MAPKs, leading to the amelioration of the phagocytic ability of EMF-stimulated N9 cells. Antagonist studies of EP1-4 receptors showed that EMF depressed the phagocytosis of fAß42 through the PGE2 system, which is linked to EP2 receptors. CONCLUSIONS: This study indicates that EMF exposure could induce phagocytic depression via JAK2-STAT3- and MAPK-dependent PGE2-EP2 receptor signaling pathways in microglia. Therefore, pharmacological inhibition of PGE2 synthesis and EP2 receptors may be a potential therapeutic strategy to combat the neurobiological deterioration that follows EMF exposure.

Cadmium Exposure Enhances Bisphenol A-Induced Genotoxicity through 8-Oxoguanine-DNA Glycosylase-1 OGG1 Inhibition in NIH3T3 Fibroblast Cells.

BACKGROUND: Both cadmium (Cd) and bisphenol A (BPA) are commonly encountered in humans' daily activities, but their combined genotoxic effects remain unclear. METHODS: In the present study, we exposed a mouse embryonic fibroblast cell line (NIH3T3) to Cd for 24 h, followed by a 24 h BPA exposure to evaluate toxicity. The cytotoxicity was evaluated by viability with CCK-8 assay and lactate dehydrogenase (LDH) release. Reactive oxygen species (ROS) production was measured by 2',7'-dichlorofluorescein diacetate (DCFH-DA). And DNA damage was measured by 8-hydroxydeoxyguanosine (8-OHdG), phosphorylated H2AX (γH2AX) and the comet assay. The flow cytometry was used to detect cell cycle distribution, and apoptosis was determined by TUNEL assay and western blot against poly-ADP-ribose polymerase (PARP). RESULTS: The results showed that Cd or BPA treatments alone (with the exception of BPA exposure at 50 µM) did not alter cell viability. However, pre-treatment with Cd aggravated the BPA-induced reduction in cell viability; increased BPA-induced LDH release, ROS production, DNA damage and G2 phase arrest; and elevated BPA-induced TUNEL-positive cells and the expression levels of cleaved PARP. Cd exposure concurrently decreased the expression of 8-oxoguanine-DNA glycosylase-1 (OGG1), whereas OGG1 over-expression abolished the enhancement of Cd on BPA-induced genotoxicity and cytotoxicity. CONCLUSION: These findings indicate that Cd exposure aggravates BPA-induced genotoxicity and cytotoxicity through OGG1 inhibition.

NiO nanoparticles induce apoptosis through repressing SIRT1 in human bronchial epithelial cells.

With application of nano-sized nickel-containing particles (Nano-Ni) expanding, the health concerns about their adverse effects on the pulmonary system are increasing. However, the mechanisms for the pulmonary toxicity of these materials remain unclear. In the present study, we focused on the impacts of NiO nanoparticles (NiONPs) on sirtuin1 (SIRT1), a NAD-dependent deacetylase, and investigated whether SIRT1 was involved in NiONPs-induced apoptosis. Although the NiONPs tended to agglomerate in fluid medium, they still entered into the human bronchial epithelial cells (BEAS-2B) and released Ni(2+) inside the cells. NiONPs at doses of 5, 10, and 20µg/cm(2) inhibited the cell viability. NiONPs' produced cytotoxicity was demonstrated through an apoptotic process, indicated by increased numbers of Annexin V positive cells and caspase-3 activation. The expression of SIRT1 was markedly down-regulated by the NiONPs, accompanied by the hyperacetylation of p53 (tumor protein 53) and overexpression of Bax (Bcl-2-associated X protein). However, overexpression of SIRT1 through resveratrol treatment or transfection clearly attenuated the NiONPs-induced apoptosis and activation of p53 and Bax. Our results suggest that the repression of SIRT1 may underlie the NiONPs-induced apoptosis via p53 hyperacetylation and subsequent Bax activation. Because SIRT1 participates in multiple biologic processes by deacetylation of dozens of substrates, this knowledge of the impact of NiONPs on SIRT1 may lead to an improved understanding of the toxic mechanisms of Nano-Ni and provide a molecular target to antagonize Nano-Ni toxicity.

[Rutin protects against trimethyltin-induced learning and memory impairment in BALB/c mice by antagonizing down-regulated synaptophysin expression].

OBJECTIVE: To explore the protective effects of rutin against learning and memory impairment induced by trimethyltin (TMT) and investigate the possible mechanism. METHODS: Forty 6- to 9-week-old male BALB/c mice were randomized equally into saline group (control), TMT group, TMT+rutin group, and rutin group. Mouse models of learning and memory impairment were establish by acute TMT (2.25 mg/kg) exposure. In TMT+rutin and rutin treatment groups, the mice received intraperitioneal injection of rutin (10 mg/kg) for 1 week before TMT exposure. Twenty-four hours after TMT exposure, Morris water maze test was employed to test the escape latency of the mice, and the synaptophysin expression in the hippocampus and cortex were analyzed by Western blotting. RESULTS: Compared that in TMT group, the escape latency of the mice in water maze test was significantly shorter in the other 3 groups (P<0.05); the escape latency in TMT +rutin group was similar with that in the control and rutin groups (P>0.05). Western blotting showed significantly decreased synaptophysin expression in the hippocampus and cortex in TMT group (P<0.05); synaptophysin expression in TMT +rutin group increased significantly compared with that in TMT group (P<0.05) but showed no statistical significance from that in rutin and control groups (P>0.05). CONCLUSION: Rutin pretreatment offers protective effect against TMT-induced learning and memory impairment in mice possibly by antagonizing decreased synaptophysin in the hippocampus and cortex.

The amelioration of phagocytic ability in microglial cells by curcumin through the inhibition of EMF-induced pro-inflammatory responses.

BACKGROUND: Insufficient clearance by microglial cells, prevalent in several neurological conditions and diseases, is intricately intertwined with MFG-E8 expression and inflammatory responses. Electromagnetic field (EMF) exposure can elicit the pro-inflammatory activation and may also trigger an alteration of the clearance function in microglial cells. Curcumin has important roles in the anti-inflammatory and phagocytic process. Here, we evaluated the ability of curcumin to ameliorate the phagocytic ability of EMF-exposed microglial cells (N9 cells) and documented relative pathways. METHODS: N9 cells were pretreated with or without recombinant murine MFG-E8 (rmMFG-E8), curcumin and an antibody of toll-like receptor 4 (anti-TLR4), and subsequently treated with EMF or a sham exposure. Their phagocytic ability was evaluated using phosphatidylserine-containing fluorescent bioparticles. The pro-inflammatory activation of microglia was assessed via CD11b immunoreactivity and the production of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1ß (IL-1ß) and nitric oxide (NO) via the enzyme-linked immunosorbent assay or the Griess test. We evaluated the ability of curcumin to ameliorate the phagocytic ability of EMF-exposed N9 cells, including checking the expression of MFG-E8, αvß3 integrin, TLR4, nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) using Western blotting. RESULTS: EMF exposure dramatically enhanced the expression of CD11b and depressed the phagocytic ability of N9 cells. rmMFG-E8 could clearly ameliorate the phagocytic ability of N9 cells after EMF exposure. We also found that EMF exposure significantly increased the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1ß) and the production of NO; however, these increases were efficiently chilled by the addition of curcumin to the culture medium. This reduction led to the amelioration of the phagocytic ability of EMF-exposed N9 cells. Western blot analysis revealed that curcumin and naloxone restored the expression of MFG-E8 but had no effect on TLR4 and cytosolic STAT3. Moreover, curcumin significantly reduced the expression of NF-κB p65 in nuclei and phospho-STAT3 (p-STAT3) in cytosols and nuclei. CONCLUSIONS: This study indicates that curcumin ameliorates the depressed MFG-E8 expression and the attenuated phagocytic ability of EMF-exposed N9 cells, which is attributable to the inhibition of the pro-inflammatory response through the NF-κB and STAT3 pathways.

Synaptophysin and the dopaminergic system in hippocampus are involved in the protective effect of rutin against trimethyltin-induced learning and memory impairment.

OBJECTIVES: This study aimed to investigate the protective effect of rutin against trimethyltin-induced spatial learning and memory impairment in mice. This study focused on the role of synaptophysin, growth-associated protein 43 and the action of the dopaminergic system in mechanisms associated with rutin protection and trimethyltin-induced spatial learning and memory impairment. METHODS: Cognitive learning and memory was measured by Morris Water Maze. The expression of synaptophysin and growth-associated protein 43 in hippocampus was analyzed by western blot. The concentrations of dopamine, homovanillic acid, and dihyroxyphenylacetic acid in hippocampus were detected using reversed phase high-performance liquid chromatography with electrochemical detection. RESULTS: Trimethyltin-induced spatial learning impairment showed a dose-dependent mode. Synaptophysin but not growth-associated protein 43 was decreased in the hippocampus after trimethyltin administration. The concentration of dopamine decreased, while homovanillic acid increased in the hippocampus after trimethyltin administration. Mice pretreated with 20 mg/kg of rutin for 7 consecutive days exhibited improved water maze performance. Moreover, rutin pretreatment reversed the decrease of synaptophysin expression and dopamine alteration. DISCUSSION: These results suggest that rutin may protect against spatial memory impairment induced by trimethyltin. Synaptophysin and the dopaminergic system may be involved in trimethyltin-induced neuronal damage in hippocampus.

Mobile phone radiation induces mode-dependent DNA damage in a mouse spermatocyte-derived cell line: a protective role of melatonin.

PURPOSE: To evaluate whether exposure to mobile phone radiation (MPR) can induce DNA damage in male germ cells. MATERIALS AND METHODS: A mouse spermatocyte-derived GC-2 cell line was exposed to a commercial mobile phone handset once every 20 min in standby, listen, dialed or dialing modes for 24 h. DNA damage was determined using an alkaline comet assay. RESULTS: The levels of DNA damage were significantly increased following exposure to MPR in the listen, dialed and dialing modes. Moreover, there were significantly higher increases in the dialed and dialing modes than in the listen mode. Interestingly, these results were consistent with the radiation intensities of these modes. However, the DNA damage effects of MPR in the dialing mode were efficiently attenuated by melatonin pretreatment. CONCLUSIONS: These results regarding mode-dependent DNA damage have important implications for the safety of inappropriate mobile phone use by males of reproductive age and also suggest a simple preventive measure: Keeping mobile phones as far away from our body as possible, not only during conversations but during 'dialed' and 'dialing' operation modes. Since the 'dialed' mode is actually part of the standby mode, mobile phones should be kept at a safe distance from our body even during standby operation. Furthermore, the protective role of melatonin suggests that it may be a promising pharmacological candidate for preventing mobile phone use-related reproductive impairments.

Melatonin ameliorates bisphenol A-induced DNA damage in the germ cells of adult male rats.

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical (EDC) that has received particular attention because of its widespread distribution in humans. Due to its chemical similarity to diethylstilbestrol, which is carcinogenic to mammals, the possible genotoxicity of BPA has already largely been evaluated. However, the results are still inconclusive and controversial. To investigate the genotoxic effects of BPA in rat germ cells and the potential protective action of melatonin against these effects, adult male Sprague-Dawley rats were orally administered BPA at a dose of 200mg/kg body weight per day for ten consecutive days with or without melatonin pretreatment. The thiobarbituric acid reactive substances (TBARS) level and superoxide dismutase (SOD) activity in the testes were evaluated. Subsequently, their spermatocytes were isolated, and DNA damage was assessed using an alkaline comet assay and the meiotic spread method. BPA administration did not significantly affect the weights of rats and their reproductive organs, and no alteration in sperm count was found. However, we demonstrated that BPA administration induced a significant increase in TBARS levels and a decrease in SOD activity that were concomitant with an increase in DNA migration within male germ cells and γH2AX foci formation on the autosomes of pachytene spermatocytes. Furthermore, a decrease in the proportion of 4C-cells was observed. These BPA effects were significantly alleviated by melatonin pretreatment. Nevertheless, the genotoxic effects of BPA were not accompanied by apoptosis in germ cells and morphological changes in the testes. These results indicate that BPA exposure may induce DNA damage accumulation in germ cells via oxidative stress. Moreover, melatonin may be a promising pharmacological candidate for preventing the potential genotoxicity of BPA following occupational or environmental exposure.

Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus.

The issue of possible neurobiological effects of the electromagnetic field (EMF) exposure is highly controversial. To determine whether electromagnetic field exposure could act as an environmental stimulus capable of producing stress responses, we employed the hippocampus, a sensitive target of electromagnetic radiation, to assess the changes in its stress-related gene and protein expression after EMF exposure. Adult male Sprague-Dawley rats with body restrained were exposed to a 2.45 GHz EMF at a specific absorption rate (SAR) of 6 W/kg or sham conditions. cDNA microarray was performed to examine the changes of gene expression involved in the biological effects of electromagnetic radiation. Of 2048 candidate genes, 23 upregulated and 18 downregulated genes were identified. Of these differential expression genes, two heat shock proteins (HSP), HSP27 and HSP70, are notable because expression levels of both proteins are increased in the rat hippocampus. Result from immunocytochemistry revealed that EMF caused intensive staining for HSP27 and HSP70 in the hippocampus, especially in the pyramidal neurons of cornu ammonis 3 (CA3) and granular cells of dentate gyrus (DG). The gene and protein expression profiles of HSP27 and HSP70 were further confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Our data provide direct evidence that exposure to electromagnetic fields elicits a stress response in the rat hippocampus.

Tau protein is involved in morphological plasticity in hippocampal neurons in response to BDNF.

Tau protein, a microtubule-associated protein involved in a number of neurological disorders such as Alzheimer's disease (AD), may undergo modifications under both physiological and pathological conditions. However, the signaling pathways that couple tau protein to neuronal physiology such as synaptic plasticity have not yet been elucidated. Here we report that tau protein is involved in morphological plasticity in response to brain derived neurotrophic factor (BDNF). Stimulation of the cultured rat hippocampal neurons with BDNF resulted in increased tau protein expression, as detected by Western blotting. Furthermore, tau protein accumulated in the distal region of the neurite when treated with taxol or taxol plus BDNF. The increased tau protein also protected neurons against nocodazole-induced dendrite loss. Moreover, BDNF promoted spine growth as well as tau protein over-expression. Knockdown of tau protein using specific short-hairpin RNA (shRNA) significantly decreased the spine density. And BDNF could not increase the spine density of tau-knockdown neurons. These results highlight a possible role for tau protein in the dynamic rearrangement of cytoskeletal fibers vital for BDNF-induced synaptic plasticity.

[Relationship between activation of microglia and Jaks phosphorylation induced by microwave irradiation].

OBJECTIVE: To explore the relationship between microglial proinflammatory and electromagnetic radiation and unveil the role of microglia in microwave radiation induced central nervous system injury. METHODS: N9 microglia cells cultured in vitro were exposed to microwave at 90 mW/cm2. Cell flow cytometry was used to observe the expression of CD11b at different time points after exposure; ELISA was used to detect the concentration of TNF-alpha in N9 cell culture supernatant; RT-PCR analysis confirmed iNOS mRNA expression in N9 microglia cells; and Nitrate Reductase Method was used to test NO amount in culture supernatant. RESULTS: The CD11b positive microglial cells increased significantly at 3 h after microwave exposure (P < 0.05), continued to increase until 24 h and peaked at 6 h after exposure. The amount of TNF-alpha rose dramatically from 1 h to 24 h after exposure (P < 0.01) and peaked at 3 h [(762.1 +/- 61.5) pg/ml] after exposure (P < 0.01). The level of NO started to increase at 1 h [(4.48-0.59) micromol/L] and lasted for 24 h after exposure. The expression of iNOS mRNA increased significantly at 1 h (P < 0.05), and tripled the original expression at 6 h after exposure, hereafter, it decreased slightly, but all were higher than the control group within 24 h after exposure. CONCLUSION: Microwave radiation could induce the activation of microglia cells. The activated microglia cells could induce microglial proinflammatory by producing large amounts of TNF-alpha, NO, etc.

[Effect of microwave irradiation on expression of heat shock proteins family in primary cultured rat hippocampal neurons].

OBJECTIVE: To investigate the effects of microwave irradiation on the expression and regulation of heat shock proteins (HSPs) in primary cultured rat hippocampal neurons. METHODS: Neurons were exposed to 90 mW/cm(2) microwave irradiation for 10 minutes. Western blot was used to determine the expression of HSP27, HSP70, HSP90 and heat shock factor 1 (HSF1) at 0, 3, 6, 12 and 24 hour respectively. Real-time RT-PCR was used to determine the mRNA expression of HSF1. DNA-binding activity of HSF1 was measured by electrophoretic mobility shift assay (EMSA). RESULTS: The protein expression of HSP27 was significantly increased by 22%, 36%, 18% at 3, 6, 12 h, respectively (P < 0.05). The protein expression of HSP70 was significantly increased by 23%, 32%, 26% at 3, 6, 12 h, respectively (P < 0.05, P < 0.01). The protein expression of HSP90 was significantly increased by 27%, 33% at 6, 12 h, respectively (P < 0.05, P < 0.01). The DNA-binding activity of HSF1 was stimulated, however, no significant change of the expression of HSF1 was observed on both the mRNA and protein levels. CONCLUSION: The transcriptional activity of HSF1 is activated by microwave irradiation, which promotes the expression of HSPs. Heat shock response which contributes to establish a cytoprotective state is induced by microwave irradiation in primary cultured rat hippocampal neurons.

[Effects of occupational microwave irradiation on heat shock protein 70 expressions in rat hippocampus].

OBJECTIVE: To study the change of heat shock protein (HSP)70 expression after exposure to occupational microwave in rats hippocampus, and explore the role of HSP70 in the mechanism of bio-effect of microwave irradiation. METHODS: The animal model was established by whole body exposures in 90, 5 W/cm(2) microwave irradiation field for 20 min in rats. Changes of the mRNA of hsp70 expressions in rat hippocampus at different time were studied by RT-PCR, and the protein change by Western blot. RESULTS: The mRNA and protein expression of hsp70 in rat hippocampus increased after 90 W/cm(2) and 5 W/cm(2) microwave irradiation for 20 min. The anal temperature and the value of SAR increased significantly. These changes were positively correlated with power and irradiation time of microwave. The results indicated that microwave irradiation led to HSP70 syntheses effectively. CONCLUSION: Microwave irradiation can obviously induce the thermal effect and activate HSP70, and initiate the endogenous protective mechanism of central nervous system.