Is the Linear No-Threshold Dose-Response Paradigm Still Necessary for the Assessment of Health Effects of Low Dose Radiation?

Inevitable human exposure to ionizing radiation from man-made sources has been increased with the proceeding of human civilization and consequently public concerns focus on the possible risk to human health. Moreover, Fukushima nuclear power plant accidents after the 2011 East-Japan earthquake and tsunami has brought the great fear and anxiety for the exposure of radiation at low levels, even much lower levels similar to natural background. Health effects of low dose radiation less than 100 mSv have been debated whether they are beneficial or detrimental because sample sizes were not large enough to allow epidemiological detection of excess effects and there was lack of consistency among the available experimental data. We have reviewed an extensive literature on the low dose radiation effects in both radiation biology and epidemiology, and highlighted some of the controversies therein. This article could provide a reasonable view of utilizing radiation for human life and responding to the public questions about radiation risk. In addition, it suggests the necessity of integrated studies of radiobiology and epidemiology at the national level in order to collect more systematic and profound information about health effects of low dose radiation.

Antidepressant effect of lentinan in chronically stressed mice and its possible mechanism / 中国免疫学杂志

Objective:By observing the hippocampus 5-HT1A receptor expression, MDA content and SOD activity and the effect of lentinan mouse model of chronic stress behavior,serum TNF-αand IL-6 content.To investigate the mechanism of antidepressant LNT.Methods:Healthy adult mice were 50,male,body weight (20 ±2) g,SPF grade,based on 1% sucrose water partial addicted degrees and were randomly divided into four groups,namely,normal control group (Normal controls,NG),model in the control group ( Model control,MG) ,LNT dose group ( L-LNT,2.5 mg/kg;H-LNT,5.0 mg/kg).Before the experiment began modeling 1 h daily oral administration,continuous administration 28 d, each experimental group administered according 1.0 ml/100 g weight.Application chronic unpredictable mild stress model of depression produced,and make improvements.Normal control group,not to stimulate,food and water properly.Model group and the experimental intervention group with the lone support,fasting,water deprivation (24 h),and accept the unpredictable stressors,the 28 d of the experiment,the animals were randomized to receive daily each only one stimulus, within five days after making the choreography the stimulus program was not repeated and unpredictable.Animals were observed daily behavior change,with a strange environment to start feeding feeding experimentally observed incubation period,forced swim stress test record swim immobility time,enzyme-linked immunosorbent assay of serum TNF-α,IL-6 content ,NBT assay of total SOD activity,thio-barbituric acid (thiobarbituric acid,TBA) MDA content assay,immune proteins mark (Western blot) to detect 5-HT1A receptor expression levels.Results:MG mice in an unfamiliar environment, feeding latency was significantly prolonged after giving LNT intervention can shorten lead to chronic stress in mice feeding latency in an unfamiliar environment,prolonged chronic stress leads to significantly reduce the stress in mice swimming in water immobility time extension,and 5-HT1A receptor expression enhancing,LNT intervention group increased SOD,MDA content decreased serum TNF-αand IL-6 was significantly reduced,compared with the model group MG indicators above improvements were statistically significant ( P<0.05 or P<0.01 ).Conclusion:LNT can significantly antagonize depressive symptoms in mouse models of chronic stress,increased locomotor activity in mice time;LNT increase SOD,MDA content may antagonize the antidepressant effects and mechanisms related to LNT.