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Objective:To establish a comet test method for detection of genotoxicity of three reference chemicals in rat liver cells. Methods:6-10 week old Sprague Dawley rats were randomly divided into 4 groups， with normal saline （0.9% NaCl solution） as negative control group. Animals in three test groups were treated， respectively， with ethyl methanesulfonate （EMS） 200 mg/kg， N-methyl-N-nitrosourea （MNU） 50 mg/kg， and D-mannitol 2 000 mg/kg. There were 10 animals in each group， 5 males and 5 females. The animals received two times （21 h interval） of test compounds through intragastric administration， and their clinical symptoms and body weight changes were recorded during the experiment. The rats were sacrificed 3 h after the last exposure. The liver was weighed， then used to prepare single-cell suspensions for the alkaline comet test which determines the average tail DNA content percentage （DNA%） of hepatocytes and other comet indicators. Results:（1） D-mannitol， EMS and MNU did not show significant toxicity in the whole animal. （2） The mean values of tail DNA content percentage （DNA%） of rat hepatocytes in EMS ［（60.07±24.69）%］ and MNU ［（41.66±22.35）%］ groups were higher than that in the negative control group ［（2.32±1.39）%］ and the difference was statistically significant （P<0.05）. The difference between D-mannitol group ［（3.06±3.30）%］ and the negative control group was not significant （P>0.05）. Conclusion:This laboratory has established a comet test method using hepatocytes from treated rats. Among three testing chemicals， EMS and MNU have displayed genotoxicity by this assay， but no genotoxicity was observed in D-mannitol treated animals.
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BACKGROUND@#Macrophages are involved in the pathogenesis of idiopathic pulmonary fibrosis, partially by activating lung fibroblasts. However, how macrophages communicate with lung fibroblasts is largely unexplored. Exosomes can mediate intercellular communication, whereas its role in lung fibrogenesis is unclear. Here we aim to investigate whether exosomes can mediate the crosstalk between macrophages and lung fibroblasts and subsequently induce fibrosis.@*METHODS@#In vivo, bleomycin (BLM)-induced lung fibrosis model was established and macrophages infiltration was examined. The effects of GW4869, an exosomes inhibitor, on lung fibrosis were assessed. Moreover, macrophage exosomes were injected into mice to observe its pro-fibrotic effects. In vitro, exosomes derived from angiotensin II (Ang II)-stimulated macrophages were collected. Then, lung fibroblasts were treated with the exosomes. Twenty-four hours later, protein levels of α-collagen I, angiotensin II type 1 receptor (AT1R), transforming growth factor-β (TGF-β), and phospho-Smad2/3 (p-Smad2/3) in lung fibroblasts were examined. The Student's t test or analysis of variance were used for statistical analysis.@*RESULTS@#In vivo, BLM-treated mice showed enhanced infiltration of macrophages, increased fibrotic alterations, and higher levels of Ang II and AT1R. GW4869 attenuated BLM-induced pulmonary fibrosis. Mice with exosomes injection showed fibrotic features with higher levels of Ang II and AT1R, which was reversed by irbesartan. In vitro, we found that macrophages secreted a great number of exosomes. The exosomes were taken by fibroblasts and resulted in higher levels of AT1R (0.22 ± 0.02 vs. 0.07 ± 0.02, t = 8.66, P = 0.001), TGF-β (0.54 ± 0.05 vs. 0.09 ± 0.06, t = 10.00, P < 0.001), p-Smad2/3 (0.58 ± 0.06 vs. 0.07 ± 0.03, t = 12.86, P < 0.001) and α-collagen I (0.27 ± 0.02 vs. 0.16 ± 0.01, t = 7.01, P = 0.002), and increased Ang II secretion (62.27 ± 7.32 vs. 9.56 ± 1.68, t = 12.16, P < 0.001). Interestingly, Ang II increased the number of macrophage exosomes, and the protein levels of Alix (1.45 ± 0.15 vs. 1.00 ± 0.10, t = 4.32, P = 0.012), AT1R (4.05 ± 0.64 vs. 1.00 ± 0.09, t = 8.17, P = 0.001), and glyceraldehyde-3-phosphate dehydrogenase (2.13 ± 0.36 vs. 1.00 ± 0.10, t = 5.28, P = 0.006) were increased in exosomes secreted by the same number of macrophages, indicating a positive loop between Ang II and exosomes production.@*CONCLUSIONS@#Exosomes mediate intercellular communication between macrophages and fibroblasts plays an important role in BLM-induced pulmonary fibrosis.
Subject(s)
Animals , Mice , Angiotensin II , Bleomycin/toxicity , Exosomes , Fibroblasts , Lung , Macrophages , Mice, Inbred C57BL , Pulmonary Fibrosis/chemically induced , Receptor, Angiotensin, Type 1ABSTRACT
<p><b>OBJECTIVE</b>To investigate the subchronic oral toxicity of silica nanoparticles (NPs) and silica microparticles (MPs) in rats and to compare the difference in toxicity between two particle sizes.</p><p><b>METHODS</b>Sprague-Dawley rats were randomly divided into seven groups: the control group; the silica NPs low-, middle-, and high-dose groups; and the silica MPs low-, middle-, and high-dose groups [166.7, 500, and 1,500 mg/(kg•bw•day)]. All rats were gavaged daily for 90 days, and deionized water was administered to the control group. Clinical observations were made daily, and body weights and food consumption were determined weekly. Blood samples were collected on day 91 for measurement of hematology and clinical biochemistry. Animals were euthanized for necropsy, and selected organs were weighed and fixed for histological examination. The tissue distribution of silicon in the blood, liver, kidneys, and testis were determined.</p><p><b>RESULTS</b>There were no toxicologically significant changes in mortality, clinical signs, body weight, food consumption, necropsy findings, and organ weights. Differences between the silica groups and the control group in some hematological and clinical biochemical values and histopathological findings were not considered treatment related. The tissue distribution of silicon was comparable across all groups.</p><p><b>CONCLUSION</b>Our study demonstrated that neither silica NPs nor silica MPs induced toxicological effects after subchronic oral exposure in rats.</p>
Subject(s)
Animals , Female , Male , Rats , Administration, Oral , Dose-Response Relationship, Drug , Nanoparticles , Toxicity , Particle Size , Rats, Sprague-Dawley , Silicon Dioxide , Toxicity , Toxicity Tests, SubchronicABSTRACT
To evaluate hormesis induced by Yttrium (Y) nitrate in male rats, Y was offered to F0 mother rats and F1 offspring at concentrations of 0, 20, 80, and 320 ppm daily from gestational day (GD) 0 through postnatal day 70 (PND 70). The F1 offspring were evaluated with respect to motor function, learning and memory, and histopathology. Administration of Y improved motor function in a dose dependent manner. In the 20 ppm group, body weight and spatial learning and memory were increased, while the latter was decreased in the 320 ppm group. Additionally, in the 20 ppm and 80 ppm, but not the 320 ppm groups, Y reduced the anogenital distance, which indicated an anti-androgen effect. These results suggest that Y follows a hormetic concentration-related trend with an inverted U-shape.
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<p><b>OBJECTIVE</b>To establish a simple but effective method of laser scanning confocal microscopic imaging for Ca2+ oscillations of pancreatic acinar cells in adult mice.</p><p><b>METHODS</b>Pancreatic acinar cells from adult Kunming mice were isolated acutely with collagenase, and then loaded with fluo-4-AM, a Ca2+ indicator. A laser scanning confocal microscope armed with 488 nm laser was employed to record the dynamic fluorescent signals in-time and synchronously while acetylcholine (ACh) was added in the pancreatic acinar cells.</p><p><b>RESULTS</b>(1) The classic pancreatic acinar cell Ca2+ oscillations were induced by a certain concentration of ACh (100 nmol/L) successfully and steadily, which could be blocked by atropine completely. (2) Plasmic Ca2+ oscillations from different parts of one acinar cell were usually with different amplitudes and almost the same frequencies. But both of amplitudes and frequencies were different among different cells. (3) The acinar cell Ca2+ oscillations were induced by ACh in a concentration-dependent manner.</p><p><b>CONCLUSION</b>The laser scanning confocal microscopic imaging for adult mouse pancreatic acinar cell Ca2+ oscillations was established successfully. The features of being easy to use, direct to see lively, high efficiency and good flexibility make it a popular tool for researchers to choose.</p>