ID Number		1610
Study Type		In Vitro
Model		1800 MHz (GSM), 2450 MHz exposure to primary neurons and microglia cultures and analysis of signaling and gene expression
Details		Rat hippocampal neurons were exposed to 1800 MHz (GSM) for 15 min/day for 8 days at 2.4 W/kg. On the 8th day following exposure, patch clamp analysis was performed on 25 cells per culture plate. The authors report exposure decreased the amplitude of AMPA miniature excitatory postsynaptic currents without a change in frequency or decay. The change in amplitude was not paralleled by a change in receptor protein density. Exposure also decreased the density of PSD95 protein (intereacts with the NMDA receptor) on dendrites. There was no effect on NMDA receptor protein or function. In a related study, the authors again exposed at 1800 Mhz (GSM) as above, this time at either 2.4 W/kg and 0.8 W/kg in a temperature controlled environment for 9 days. The authors report at the highest exposure level dendridic filopodia density and mobility decreased (38.5 +/- 5.8 % and 28 +/- 6 %, respectively). The resulting length of dendritic branches was also decreased over the course of the study. There was no change in filopodia length. At 0.8 W/kg, there were no effects. The authors also report exposure of primary neurons to 1800 MHz (GSM) at 2 W/kg for 24 hours increased levels of oxidative damamge (e.g., 8-hydroxyguanine) and decreased mitochondrial RNA levels, with the effects being reversible with added melatonin free radical scavanger. In a related study, exposure of mouse N9 microglia cells to 2450 MHz (CW) resulted in increased STAT3 DNA binding ability, activation of Jak1 and Jak2 kinases, and expression of inflammatory signals iNOS and TNF-alpha. Activation of microglia cells is thought to play a role in the inflammatory cascade leading to neurodegenerative conditions such as Alzheimer's disease. AUTHORS' ABSTRACT: Zhang et al. 2013 (IEEE #5294): Purpose: Several studies suggest that radiofrequency electromagnetic field (RF-EMF) exposure can induce neuronal injury. The aim of the present work was to investigate whether the cyclin-dependent kinase 5 (CDK5) pathway is involved in neuronal injury induced by RF-EMF exposure. Materials and methods: Newborn Sprague-Dawley rats' primary cultured cortical neurons were exposed to pulsed 2.45 GHz RF-EMF for 10 min. The cellular viability was assessed using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The apoptosis was assessed by Hoechst 33342 and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling co-staining. The protein expressions of CDK5, p35, p25, and phosphorylated tau at Ser404 were examined by Western blot analysis. The CDK5 activity was detected using a histone-H1 kinase assay. Results: The cellular viability of neurons was significantly decreased (p < 0.01, Partial Eta Squared [·p2]: 0.554), and the percentage of apoptotic nuclei (p < 0.01, ·p2 = 0.689), activity of CDK5 (p < 0.05, ·p2 = 0.589), ratio of p25 and p35 (p < 0.05, ·p2 = 0.670), levels of tau phosphorylation at Ser404 (p < 0.01, ·p2 = 0.896) were significantly increased after RF-EMF exposure. No significant change was detected in CDK5 expression after RF-EMF exposure. Pretreatment with Roscovitine (a CDK5 inhibitor) significantly blocked the RF-EMF-induced decrease of cellular viability (p < 0.05, ·p2 = 0.398) and tau hyperphosphorylation at Ser404 (p < 0.01, ·p2 = 0.917), but did not significantly block the RF-EMF-induced apoptosis (p > 0.05, ·p2 = 0.130). Conclusions: These results suggest that abnormal activity of p25/CDK5 is partially involved in primary cultured cortical neuron injury induced by RF-EMF exposure. AUTHORS' ABSTRACT: He et al. 2014 (IEEE #5465): 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-± (TNF-±), interleukin-6 (IL-6), interleukin-1² (IL-1²) 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, ±v²3 integrin, TLR4, nuclear factor-ºB (NF-ºB) 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-±, IL-6 and IL-1²) 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-ºB 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-ºB and STAT3 pathways.
Findings		Effects
Status		Completed With Publication
Principal Investigator		3rd Military Medical University, Chongqing, China
Funding Agency		China National Natural Sc Found
Country		CHINA
References		Hao, Y et al. Int J Radiat Biol, (2010) 86:27-36 Xu, S et al. Brain Res, (2010) 1311:189-196 Ning, W et al. Acta Pharmacol Sin, (2007) 28:1873-1880 Xu, SJ et al. Neurosci Lett., (2006) 398:253-257 Zhang, Y et al. Int J Radiat Biol., (2013) 89:976-984 He, GL et al. Journal of Neuroinflammation., (2014) 11:49-(13 pages)
Comments