OBJECTIVETo explore the effect of low doses X-ray on proliferation of hippocampal pyramidal cell in the area of CA1 in prenatal rat and its relevant mechanism.

METHODSA total of 25 pregnant rats were randomly divided into four experimental groups and one control group. The experimental groups, in a duration of consistent 18 days, respectively received different doses as follows: 0.015 mGy/d, 0.03 mGy/d, 0.06 mGy/d and 0.09 mGy/d. The control group received sham radiation. To observe the density and width of hippocampal pyramidal cell in the area of CA1 by HE stained and observe the expression of the ERK1/2 by IHM.

RESULTS(1) Except C group, all other groups presented increment in width of the level of hippocampal pyramidal cell, compared with C group; H group, M group, L1 group and L2 group were higher than that (F value respectively were 8.475, 33.42, 14.395, 44.955; P value respectively were 0.002, 0.048, 0.030, 0.012). But the phenomenon of inhomogeneity in width in H group was observed, at the same time, the density of cell in H group became looser (F = 4.466, P = 0.017). (2) The expression of ERK1/2 in the hippocampus CA1 was seen in cytoplasm of every group, the average optical density of positive ERK1/2 protein significantly increased in L1 group and L2 group, compared with control group respectively (F value respectively were 4.561, 4.103, P value respectively were 0.044, 0.035).

CONCLUSIONLow doses X-ray could promote proliferation of hippocampus CA1 cell in prenatal. The reason could be the increment of the ERK1/2 protein induced by X-ray. When the doses reached 0.09 mGy/d, the excesses proliferation phenomenon was observed.

Animals ; Cell Proliferation ; radiation effects ; Female ; Hippocampus ; cytology ; radiation effects ; Male ; Maternal Exposure ; Neurons ; cytology ; radiation effects ; Pregnancy ; Pyramidal Cells ; cytology ; radiation effects ; Radiation, Ionizing ; Rats ; X-Rays

The purpose of this study is to investigate the mechanism of alternative responses to low dose irradiation for neuronal cell proliferation in the dentate gyrus of rats. To determine the effect of a single exposure to radiation, rats were irradiated with a single dose of 0.1, 1, 10 or 20 Gy. To determine the effect of the cumulative dose, the animals were irradiated daily with 0.01 Gy or 0.1 Gy from 1 to 4 days. The neuronal cell proliferation was evaluated using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Four consecutive daily irradiations with a 0.01 Gy/fraction increased the number of BrdU-positive and Ki-67-positive cells in a dose dependent manner, but this did not affect the number of TUNEL-positive cells. However, there was not a dose dependent relationship for the 0.1 Gy/fraction irradiation with the number of BrdU, Ki-67 and TUNEL positive cells. Our data support the explanation that the adaptive response, induced by low-dose radiation, in the hippocampus of rats is more likely a reflection of the perturbations of cell cycle progression.
Rats, Sprague-Dawley ; Rats ; Radiation Dosage ; Neurons/*cytology/*radiation effects ; Neuronal Plasticity/*radiation effects ; Male ; Dose-Response Relationship, Radiation ; Dentate Gyrus/*cytology/*radiation effects ; Cell Survival/radiation effects ; Cell Proliferation/*drug effects ; Animals ; Adaptation, Physiological/radiation effects

OBJECTIVEIn order to explore effect of electromagnetic radiation on learning and memory ability of hippocampus neuron in rats, the changes in discharge patterns and overall electrical activity of hippocampus neuron after electromagnetic radiation were observed.

METHODSRat neurons discharge was recorded with glass electrode extracellular recording technology and a polygraph respectively. Radiation frequency of electromagnetic wave was 900 MHZ and the power was 10 W/m2. In glass electrode extracellular recording, the rats were separately irradiated for 10, 20, 30, 40, 50 and 60 min, every points repeated 10 times and updated interval of 1h, observing the changes in neuron discharge and spontaneous discharge patterns after electromagnetic radiation. In polygraph recording experiments, irradiation group rats for five days a week, 6 hours per day, repeatedly for 10 weeks, memory electrical changes in control group and irradiation group rats when they were feeding were repeatedly monitored by the implanted electrodes, observing the changes in peak electric digits and the largest amplitude in hippocampal CA1 area, and taking some electromagnetic radiation sampling sequence for correlation analysis.

RESULTS(1) Electromagnetic radiation had an inhibitory role on discharge frequency of the hippocampus CA1 region neurons. After electromagnetic radiation, discharge frequency of the hippocampus CA1 region neurons was reduced, but the changes in scale was not obvious. (2) Electromagnetic radiation might change the spontaneous discharge patterns of hippocampus CA1 region neurons, which made the explosive discharge pattern increased obviously. (3) Peak potential total number within 5 min in irradiation group was significantly reduced, the largest amplitude was less than that of control group. (4) Using mathematical method to make the correlation analysis of the electromagnetic radiation sampling sequence, that of irradiation group was less than that of control group, indicating that there was a tending to be inhibitory connection between neurons in irradiation group after electromagnetic radiation.

CONCLUSIONElectromagnetic radiation may cause structure and function changes of transfer synaptic in global, make hippocampal CA1 area neurons change in the overall discharge characteristic and discharge patterns, thus lead to decrease in the ability of learning and memory.

Animals ; CA1 Region, Hippocampal ; cytology ; radiation effects ; Electromagnetic Radiation ; Male ; Neurons ; physiology ; radiation effects ; Rats ; Rats, Wistar

OBJECTIVETo explore the effect of static magnetic field (SMF) on the differentiation and proliferation of rat embryonic midbrain neurons cells.

METHODSThe micromass culture of rat embryonic midbrain neurons cell was applied to study the effect of varieties of SMF (1.0, 10.0, 50.0, 100.0, 200.0 mT) and FACS.

RESULTSSMF inhibited the differentiation of the cell without affecting cell proliferation. The concentration of 50% inhibition of cell differentiation (ICD(50)) was 25 mT. The concentration of 50% inhibition of cell differentiation (IVD(50)) was 45 mT.

CONCLUSIONSThe inhibition of SMF on embryonic midbrain neurons cells may be associated with impact of protein syntheses, and lipid peroxidation.

Animals ; Cell Differentiation ; radiation effects ; Cell Division ; radiation effects ; Cells, Cultured ; Electromagnetic Fields ; adverse effects ; Embryo, Mammalian ; Female ; Lipid Peroxidation ; radiation effects ; Mesencephalon ; cytology ; radiation effects ; Neurons ; cytology ; radiation effects ; Protein Biosynthesis ; radiation effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo analyze the effects of high-frequency electromagnetic field (HF-EMF, 30 MHz, 0-1600 V/m) on the apoptosis and ultramicrostructure of the hippocamp and demonstrate the cytotoxicity of hippocamp.

METHODS120 Wistar female adult rats were randomly divided into ten groups based on body weight with different levels of 30 MHz electromagnetic field (0, 25, 100, 400, 1600 V/m) for eight hours daily. Five group rats were irradiated for three days. The other five group rats were irradiated for fifty-six days. Weekly the rats were continuously exposed five days. The apoptotic rate of the hippocamp was detected with TUNEL System. Meanwhile, the ultramicrostructure was observed with the transmission electron microscope.

RESULTS(1) There was no significant difference on the apoptotic rate and pathological change of the hippocamp cell between the exposure and the control groups through short term experiment (P > 0.05). (2) The apoptotic rate of the granulocyte on the DG campus of the hippocamp in the 400 V/m group and the 1600 V/m group (0.165% +/- 0.049%, 0.189% +/- 0.049% respectively) were increased significantly (P < 0.01) through inferior chronic experiment compared with the control group (0.052% +/- 0.016%). Along with the increase of radiation dose, the ultramicrostructure of the neuron cell appeared more abnormal cells. Especially there were marked change on the neuron in the 1600 V/m group.

CONCLUSIONSThere is no association between cell apoptotic rate of the hippocamp and short period exposure to HF-EMF (30 MHz, 25-1600 V/m). However inferior chronic exposures to HF-EMF might induce the cytotoxicity, especially in the high dose exposure (1600 V/m) under our experiment.

Animals ; Apoptosis ; radiation effects ; Electromagnetic Fields ; Endocytosis ; radiation effects ; Female ; Hippocampus ; cytology ; pathology ; radiation effects ; Neurons ; pathology ; radiation effects ; Rats ; Rats, Wistar

OBJECTIVEAdipose tissue distributes widely in human body. The irradiation response of the adipose cells in vivo remains to be investigated. In this study we investigated irradiation response of adipose-derived stem cells (ASCs) under three-dimensional culture condition.

METHODSASCs were isolated and cultured in low attachment dishes to form three-dimensional (3D) spheres in vitro. The neuronal differentiation potential and stem-liked characteristics was monitored by using immunofluoresence staining and flow cytometry in monolayer and 3D culture. To investigate the irradiation sensitivity of 3D sphere culture, the fraction of colony survival and micronucleus were detected in monolayer and 3D culture. Soft agar assays were performed for measuring malignant transformation for the irradiated monolayer and 3D culture.

RESULTSThe 3D cultured ASCs had higher differentiation potential and an higher stem-like cell percentage. The 3D cultures were more radioresistant after either high linear energy transfer (LET) carbon ion beam or low LET X-ray irradiation compared with the monolayer cell. The ASCs' potential of cellular transformation was lower after irradiation by soft agar assay.

CONCLUSIONThese findings suggest that adipose tissue cell are relatively genomic stable and resistant to genotoxic stress.

Adipose Tissue ; cytology ; radiation effects ; Cell Culture Techniques ; Cell Differentiation ; Flow Cytometry ; Humans ; Neurons ; cytology ; Stem Cells ; cytology ; radiation effects ; X-Rays

This in vitro study evaluated the detrimental effect of acute gamma (gamma)-irradiation on rat immature hippocampal neurons. Rat immature hippocampal neurons (0.5 day in vitro) were irradiated with 0~4 Gy gamma-rays. Cytotoxicity was analyzed using a lactate dehydrogenase release assay at 24 h after gamma-irradiation. Radiation-induced cytotoxicity in immature hippocampal neurons increased in a dose-dependent manner. Pre-treatments of pro-apoptotic caspase inhibitors and anti-oxidative substances significantly blocked gamma-irradiation-induced cytotoxicity in immature hippocampal neurons. The results suggest that the caspase-dependent cytotoxicity of gamma-rays in immature hippocampal cultured neurons may be caused by oxidative stress.
Amifostine/pharmacology ; Animals ; Antioxidants/pharmacology ; Caspase 3/metabolism/radiation effects ; Catechin/analogs & derivatives/pharmacology ; Cell Survival/radiation effects ; Cells, Cultured/cytology/enzymology/*radiation effects ; Dose-Response Relationship, Radiation ; Female ; *Gamma Rays ; Hippocampus/cytology/enzymology/*radiation effects ; L-Lactate Dehydrogenase/radiation effects ; Neurons/cytology/enzymology/*radiation effects ; Poly(ADP-ribose) Polymerases/drug effects ; Pregnancy ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo explore the injury effect and mechanism of hypothalamic neurons after high power microwave (HPM) exposure.

METHODSPrimarily cultured hypothalamic neurons were exposed to 10 and 30 mW/cm(2) HPM, and the inverted phase contrast microscope (IPCM) and flow cytometry (FCM) were employed to detect the injury of cells and change of mitochondrion membrane potential (MMP) and Ca(2+) in the cytoplasm of neurons.

RESULTSThe ratio of apoptosis was significantly higher than that of the sham exposure (P < 0.05) induced by 10 and 30 mW/cm(2) HPM and necrosis increased significantly (P < 0.05) in the group of 30 mW/cm(2) at 6 h after exposure. The content of Ca(2+) in the cytoplasm of neuron cells increased (P < 0.01) while MMP decreased significantly (P < 0.01) after radiation of 30 mW/cm(2) HPM at 6 h after exposure.

CONCLUSIONApoptosis is one of the major death ways of hypothalamic neurons. The overloading of Ca(2+) and the decline of MMP are involved in the process.

Animals ; Apoptosis ; radiation effects ; Calcium ; metabolism ; Cells, Cultured ; Hypothalamus ; cytology ; radiation effects ; Membrane Potential, Mitochondrial ; radiation effects ; Membrane Potentials ; Microwaves ; adverse effects ; Neurons ; metabolism ; radiation effects ; Rats ; Rats, Wistar

OBJECTIVEThe 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.

METHODS48 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.

RESULTSMicrowave 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.

CONCLUSION30 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.

Animals ; Gene Expression Regulation ; radiation effects ; Hippocampus ; cytology ; Microwaves ; Neuronal Plasticity ; radiation effects ; Neurons ; radiation effects ; Neurotransmitter Agents ; metabolism ; PC12 Cells ; Rats ; Receptors, N-Methyl-D-Aspartate ; genetics ; metabolism ; Signal Transduction ; physiology ; radiation effects ; Time Factors

OBJECTIVETo evaluate the effect of neuronal differentiation induced by nerve growth factor (NGF) on the tolerance-dosage of ultraviolet radiation of PC12 Cells.

METHODSNeuron-differentiated PC12 cells and untreated PC12 cells were exposed to different ultraviolet radiation dosage of 10, 30, 60, 80, 100, and 200 mJ/cm2. Cell survival rates were determined by MTT assay.

RESULTSNeuron-differentiated PC12 cells had increased tolerance dose to ultraviolet radiation with noticeable apoptosis at the radiation dose of 100 mJ/cm2 in contrast to 30 mJ/cm2 for normal PC12 cells.

CONCLUSIONNeuronal differentiation exerts the effect of increasing the tolerance dose of PC12 cells to ultraviolet radiation.

Animals ; Cell Differentiation ; Cell Transformation, Neoplastic ; drug effects ; radiation effects ; Dose-Response Relationship, Radiation ; Nerve Growth Factor ; pharmacology ; Neurons ; cytology ; PC12 Cells ; Rats ; Ultraviolet Rays