Effects of high frequency flash stimulation on the capacity of learning memory and autonomous exploratory in young rats / 中华行为医学与脑科学杂志

Objective:To investigate the effects of 40 Hz and 70 Hz frequency flash stimulation on the ability of learning memory and autonomous exploratory in young rats.Methods:Twenty-seven SPF grade male SD rats aged 19-21 days were divided into control group (Ctr group), 40 Hz group and 70 Hz group with 9 in each group according to the random number table.The rats in Ctr group were not given flash stimulation, while rats in the 40 Hz and 70 Hz group were received 40 Hz, 70 Hz flash stimulation (1.5 h/d for 39 days), respectively.The Morris water maze experiment was used to assess the learning and memory ability of rats, and the open field experiment was used to evaluate the ability of autonomous exploratory of rats.Nissl staining was used to assess the morphology of Nissl bodies in the hippocampus CA1 region of the rats.The local field potentials (LFPs) collected from the primary visual cortex (V1 area) region by electrophysiological experiments was used to verify the synchronization of flash evoked neural oscillations.SPSS 23.0 software was used for statistical analysis.The repeated measures ANOVA and one-way ANOVA were used to analyze normal distribution measurement data, and LSD and Tamhane tests were used for further pairwise comparison.The Kruskal-Wallis test was used for non-normal distribution measurement data.Results:(1) The flash stimulation of 40 Hz and 70 Hz both can effectively caused synchronization of neural oscillations in the primary visual cortex of healthy young rats.(2) The results of repeated measures ANOVA analysis showed that there was no interaction effect of grouping and time in the escape latency of young rats in the Morris water maze positioning navigation phase( F=1.326, P>0.05 ). The escape latency had time main effect ( F=40.025, P<0.05), but no grouping main effect ( F=2.039, P>0.05). With the increase of learning days, the escape latency of young rats in each group decreased significantly.There was no interaction effect of grouping and time in the total distance of young rats ( F=2.029, P>0.079). It had time main effect ( F=32.052, P<0.05), but not grouping main effect ( F=2.390, P>0.05) on total distance.With the increase of learning days, the total distance of young rats in each group significantly shortened.On the 6th day of the Morris water maze experiment, there was no statistically significant difference among groups in terms of time in the target quadrant and the number of crossing platforms ( F=2.511, 0.802, both P>0.05). The results of the open field experiment showed that the total distance traveled in the center of young rats in each group was statistically significant ( H=8.935, P<0.05), the total distance traveled in the center in the 70 Hz group (3.80 (2.25, 6.93) m)was significantly longer than that in the 40 Hz group (0.80 (0.72, 1.46) m), P<0.05). The percentage of time spent in the center was statistically significant in the three groups ( H=11.050, P<0.05). Young rats in the 70 Hz group spent significantly higher percentage of time in the center(3.20(2.43, 8.30)) than those in the 40 Hz group (0.95 (0.37, 1.06 ), P<0.05 ). (3) Nissl staining results showed that Nissl bodies in the hippocampal CA1 area of young rats in Ctr, 40 Hz and 70 Hz group were all arranged neatly and tightly, no edema was found in the surrounding stroma, and no obvious inflammatory cell infiltration was found. Conclusion:70 Hz frequency flash stimulation may promote the ability of learning memory and autonomous exploratory of young rats.

Secretion of reproductive hormones and estrous cycle in rats interfered by combined exposure to beta-cypermethrin and emamectin benzoate / 环境与职业医学

Backgroud Beta-cypermethrin and emamectin benzoate are widely used for the prevention and control of pests in the greenhouse planting industry, and their combined exposure may increase the accumulation of beta-cypermethrin and emamectin benzoate in organisms and affect human health. Objective Based on the changes in reproductive hormone levels in the hypothalamic-pituitary-ovarian (HPO) axis, to investigate the effect of combined exposure to beta-cypermethrin and emamectin benzoate on the estrous cycle of female mice. Methods Twenty-four healthy adult SD rats were randomly divided into a blank control group, a beta-cypermethrin group (Beta-CYP, 53 mg·m−3), an emamectin benzoate group (EMB, 8 mg·m−3), and a beta-cypermethrin and emamectin benzoate combined exposure group (Beta-CYP+EMB, Beta-CYP 53 mg·m−3 + EMB 8 mg·m−3). Six rats in each group were exposed to the designed treatment protocol by aerosol inhalation 6 d a week for 13 weeks. The general condition of the rats was observed in real time during the treatment. From the 12th week of exposure, a 10-day reproductive tract smear was performed on the rats to observe the estrous cycle. The rats were neutralized on the second day after the end of the treatment protocol, and the ovarian tissues were stained with HE to observe histopathological changes. Serum levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol (E2) were measured by ELISA. Experimental results were expressed as mean ± standard deviation (\begin{document}$ \overline{x}\pm s $\end{document}). One-way ANOVA was used for comparison among groups, and LSD test for pairwise comparison between groups. The significance level was α=0.05. Results After four weeks of the treatment protocol, the rats in the Beta-CYP group and the Beta-CYP+EMB group continued to be hyperactive and irritable, while the EMB group showed symptoms of mental disorder, decreased activity, and slow response. On the 90th day of the treatment protocol, the body weight of rats in the control group increased to (314.51±2.44) g, and that in the Beta-CYP+EMB group only increased to (253.47±1.50) g. There was no abnormal cellular morphology in the control group; however, small deeply stained nuclei appeared in the Beta-CYP group, the EMB group, and the Beta-CYP+EMB group, and abnormal morphological development of keratinized epithelial cells in the Beta-CYP+EMB group was found. The estrous cycle of rats in the control group was (97.83±4.17) h, and compared with the control group, the estrous cycles of rats in the Beta-CYP group, the EMB group, and the Beta-CYP+EMB group were prolonged to (134.33±7.53) h, (126.50±5.28) h, and (156.00±6.66) h, respectively. The results of ANOVA showed that the numbers of leukocytes (527.17±15.83), keratinized epithelial cells (35.67±4.32), and non-keratinized epithelial cells (70.50±4.51) in the vaginal smears during diestrus in the Beta-CYP+EMB group were significantly lower than those in the control group (752.50±28.89, 50.50±2.74, 101.33±7.92) (P<0.001). The hormone levels of GnRH and FSH in the control group were (5.13±0.59) and (0.76±0.09) IU·L−1 respectively, while the levels in the Beta-CYP+EMB group were increased to (16.86±0.59) and (3.80±0.19) IU·L−1 respectively (P<0.05). The levels of LH and E2 in the control group were (12.93±0.81) IU·L−1 and (22.23±1.44) pmol·L−1 respectively, and the levels in the Beta-CYP+EMB group were decreased to (5.63±0.41) IU·L−1 and (10.45±0.78) pmol·L−1 respectively (P<0.05). Conclusion The combined exposure to beta-cypermethrin and emamectin benzoate may ultimately affect the estrous cycle of female rats by interfering with the secretion of reproductive hormones involved in the HPO axis.

Mechanism of silica-induced ROS over synthsis in NLRP3-dependent macrophage pyroptosis / 环境与职业医学

Background Macrophages are essential components of the natural immune system. They play a significant role in resisting foreign bodies in the respiratory tract and maintaining the homeostasis of the internal environment of lung tissue. Objective To investigate the mechanism of macrophage pyroptosis induced by silica dust with different particle sizes. Methods The modified murine macrophage cell line, RAW-ASC cells, was cultured and divided into a blank control group, a lipopolysaccharide (LPS) group (1 μg·mL−1 LPS), a nano-SiO2 group (1 μg·mL−1 LPS+100 μg·mL−1 nano-SiO2), a micro-SiO2 group (1 μg·mL−1 LPS+750 μg·mL−1 micro-SiO2), and a positive control group [1 μg·mL−1 LPS+3 mmol·L−1 adenosine triphosphate (ATP)]. Apart from the blank control group, cells in other groups were pretreated with LPS for 6 h, and then exposed to SiO2 or ATP for 4 h. According to the molecular target NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and reactive oxygen species (ROS), we applied MCC950 (NLRP3 inhibitor) and N-acetyl cysteine (NAC, ROS scavenger) to macrophages. CCK-8 assay was used to detect cell viability; 5-ethynyl-2'-deoxyuridine (EdU) staining was used to detect cell proliferation; lactate dehydrogenase (LDH) assay kit was used to detect LDH in supernatant; calcein AM/PI fluorescent double-staining was applied to evaluate cell rupture; 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescent probe was used to measure the content of ROS; Western blotting was used to measure the expressions of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), Caspase-1, gasdermin D (GSDMD), and interleukin-1β (IL-1β). Results Compared with the blank group, 100 μg·mL-1nano-SiO2 and 750 μg·mL-1micro-SiO2 dust exposure reduced the cell viability to 40% and 68% (P<0.05), and the cell proliferation rate to 30% and 33% (P<0.01), respectively; they also induced cell lysis and ROS release, upregulated NLRP3, ASC, Caspase-1, GSDMD, and IL-1β at protein level (P<0.05), and induced macrophage pyroptosis. After intervening with MCC950 (10 μmol·L-1) and NAC (10 mmol·L-1), the expressions of NLRP3, ASC, Caspase-1, and IL-1β decreased (P<0.05), and, specifically, NAC effectively reduced ROS levels (P<0.05). Conclusion Both nano- and micro-SiO2 dust have cytotoxicity, can upregulate ROS level, activate NLRP3 inflammasome, and promote the release of cytokines, leading to pyroptosis. These results are helpful to reveal the molecular mechanism of macrophage pyroptosis induced by SiO2 dust.

Effect of nano-silica dust exposure on gene expression of macrophages / 中国职业医学

OBJECTIVE: To detect the expression of differential expression genes(DEGs) on microarray chips of macrophages exposed to nano-silicon dioxide(SiO_2) dust, and to screen the leading signaling pathway of nano-SiO_2 dust exposure-related diseases. METHODS: The gene chip GSE13005 of RAW264.7 macrophage intervened by nano-SiO_2 dust was obtained from the public gene chip database developed by the National Center for Biotechnology Information. The macrophages in the control group were cultured in complete medium without adding SiO_2 dust, whereas the macrophages in the exposure group were treated with SiO_2 dust with the final concentrations of 5, 20, and 50 mg/L. The gene expression data of macrophages was analyzed by RMA Express 1.2.0 software and R language 3.5.1. The Kyoto Encyclopedia of Genes and Genomes(KEGG) was used to screen DEGs and perform gene ontology(GO) enrichment analysis on related genes and signaling pathways. RESULTS: A total of 67 DEGs of macrophages were screened after SiO_2 dust treatment, of which 48 genes were up-regulated and 19 genes were down-regulated. GO enrichment analysis results showed that the main functional items of participating DEGs were reaction of amine, regulation of viral genome replication,negative regulation of amino acid transport, ovulation, bronchodilator response, chemokine activity, negative regulation of muscle cell differentiation, response to lack of amino acid, positive regulation of glomerular mesangial cell proliferation, and positive regulation of vascular smooth muscle cell proliferation. KEGG signaling pathway analysis results suggested that DEGs could function through 7 signaling pathways including nuclear transcription factor-κB(NF-κB) signaling pathway, p53 signaling pathway, glioma, melanoma, toll-like receptor signaling pathway, renal cell carcinoma and salmonella infection. Further functional enrichment revealed that NF-κB signaling pathway changed most significantly after macrophages were exposed to nano-SiO_2 dust. CONCLUSION: Exposure to nano-SiO_2 could induce the abnormal expression of 67 genes in macrophages. The genes that participated in macrophage activation process induced by nano-SiO_2 dust exposure are related to NF kappa B signaling pathway.

Current status of the training model of full-time professional postgraduate students in public health in Australia and Japan and their reference significance / 中华医学教育探索杂志

With the increasing frequency and impact of public health incidents in the world's medical and health services in recent years,it has become extremely necessary to train public health talents suitable for the medical environment in China.This article mainly discusses the training model of professional postgraduate students in public health in Australian universities (Sydney University and Melbourne University) and Japanese universities (Tokyo University and Hokkaido University).Both countries attach importance to the education of practical ability.Australian universities focus on the training of allround and comprehensive public health talents,while Japanese universities emphasizes the training of professional public health talents.At present,there is a lack of a clear understanding of public health and detailed standards in China,which is the main problem of public health education in China.A detailed and efficient training model of public health talents should be established based on the unique features of our country.

Endonuclease modified comet assay for oxidative DNA damage induced by detection of genetic toxicants / 中华预防医学杂志

<p><b>OBJECTIVE</b>The aim of this study was to investigate the use of the lesion-specific endonucleases-modified comet assay for analysis of DNA oxidation in cell lines.</p><p><b>METHODS</b>DNA breaks and oxidative damage were evaluated by normal alkaline and formamidopyrimidine-DNA-glycosylase (FPG) modified comet assays. Cytotoxicity were assessed by MTT method. The human bronchial epithelial cell (16HBE) were treated with benzo (a) pyrene (B(a)P), methyl methanesulfonate (MMS), colchicine (COL) and vincristine (VCR) respectively, and the dose is 20 µmol/L, 25 mg/ml, 5 mg/L and 0.5 mg/L for 24 h, respectively. Oxidative damage was also detected by levels of reactive oxygen species in treated cells.</p><p><b>RESULTS</b>Four genotoxicants give higher cytotoxicity and no significant changes on parameters of comet assay treated by enzyme buffer. Cell survival rate were (59.69 ± 2.60) %, (54.33 ± 2.81) %, (53.11 ± 4.00) %, (51.43 ± 3.92) % in four groups, respectively. There was the direct DNA damage induced by test genotoxicants presented by tail length, Olive tail moment (TM) and tail DNA (%) in the comet assay. The presence of FPG in the assays increased DNA migration in treated groups when compared to those without it, and the difference was statistically significant which indicated that the clastogen and aneugen could induce oxidative damage in DNA strand. In the three parameters, the Olive TM was changed most obviously after genotoxicants treatment. In the contrast group, the Olive TM of B(a) P,MMS, COL,VCR in the contrast groups were 22.99 ± 17.33, 31.65 ± 18.86, 19.86 ± 9.56 and 17.02 ± 9.39, respectively, after dealing with the FPG, the Olive TM were 34.50 ± 17.29, 43.80 ± 10.06, 33.10 ± 12.38, 28.60 ± 10.53, increased by 58.94%, 38.48%, 66.86% and 68.21%, respectively (t value was 3.91, 3.89, 6.66 and 3.87, respectively, and all P < 0.05), and the correlation between Olive TM and reactive oxygen species was better than other parameters (r = 0.77, P < 0.05).</p><p><b>CONCLUSION</b>This study indicates that FPG-comet assay appears more specific for detecting oxidative DNA damage induced by genotoxicants exposure, and the application of comet assay will be expanded. The endonuclease modified comet assay will be used widely in the toxicology and molecular epidemiology study.</p>

Delayed protection of HO-1 in the exercise preconditioning from the myocardial relative ischemic reperfusion injury / 中国病理生理杂志

AIM: To explore the delayed protection of heme oxygenase-1 (HO-1) in the exercise preconditioning (EP) from the myocardial relative ischemia reperfusion injury (rI/R). METHODS: 40 Wistar Rats were divided into 5 groups randomly: control group (CN), rI/R group (IR), EP+rI/R group (EI), HO-1 inductor hemin+rI/R group (HE) and HO-1 inhibitor ZnPP+EP+rI/R group (EZ). The following indexes were detected, including the HO-1activity in myocardium, the cardiac function parameter-pressure-rate product (heart rate × left ventricular developed pressure, PRP) and the content of MDA in coronary effluent. RESULTS: After myocardial rI/R, HO-1 activity increased significantly. Moreover, EP or HO-1 inductor could enhance this effect manifestly. Nevertheless, when the HO-1 inhibitor was administered before EP,HO-1 activity decreased. In addition, there was no distinct difference in the HO-1 activity between EI group and HE group. At the 30 min point of reperfusion, the PRP recovery rate of EI group was higher clearly than that of IR group. However, there was reverse effect between the EZ group and the EI group. The MDA in coronary effluent of EI group, EZ group and HE group were lower obviously than that of IR group and there was significant difference between EI group and EZ group. CONCLUSION: EP could protect the heart from the rI/R injury occurring 24 hours later, which might be performed through activating the HO-1.