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OBJECTIVE: To investigate the chronic toxicity and carcinogenicity of kresoxim-methyl in rats. METHODS: Specific pathogen free SD rats were randomly divided into control group and low-, medium-and high-dose groups according to the body weight of rats, 120 rats in each group with half male and half female rats. The chronic toxicity and carcinogenesis was induced in rats for 104 weeks by oral feeding. The dose of kresoxim-methyl in feed of male and female rats was 0, 75, 300 and 1 200 mg/kg. During the process of experiment, the body weight of rats was weighed. The blood biochemistry, organ coefficient and histopathology were examined at the end of the exposure, and the tumor incidence was calculated. RESULTS: There was no significant difference in mortality of the female or male rats in the four groups(P>0.05). At the 32 nd, 48 th and 56 th week after exposure, the body mass of female rats in the high dose group was lower than that in control group(P<0.05); at the 8 th, 16 th, 24 th and 32 nd week, the body mass of male rats in the high dose group was lower than that in the control group(P<0.05). The organ coefficients of heart and adrenal gland of female rats in the high dose group were higher than those in the control group and the low dose group(P<0.05). The organ coefficient of liver of male rats in the high dose group was lower than that in the control group(P<0.05). The alkaline phosphatase of male rats in the three dose groups was lower than that in the control group(P<0.05). The blood glucose of male rats in the high dose group was higher than that in the control group(P<0.05). The aspartate aminotransferase of male rats in the high dose group was lower than that in the control group(P<0.05). There was no significant difference among the three indexes in female rats(P>0.05). The tumor incidence of the control group and the low, medium and high dose groups were 68.3%, 75.0%, 75.0% and 78.8%, respectively, with no significant difference(P>0.05). The tumor incidence of the female rats was higher than that of the male rats(87.0% vs 61.5%,P<0.01).The tumor multiplicity of the above four groups were 38.3%, 35.8%, 35.0%, 39.8%, respectively, with no significant difference(P>0.05). The tumor multiplicity in female rats was higher than that in male rats(56.9% vs 17.6%,P<0.01). CONCLUSION: The no observed adverse effect level of kresoxim-methyl to female and male SD rats was 24.726 and 20.002 mg/(kg·d), respectively. No carcinogenicity of kresoxim-methyl to SD rats was observed.
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OBJECTIVE: To evaluate the effect of different types of microplate and loading volumes on the detection results of multi-function microplate reader, and to optimize the analysis method. METHODS: A multi-function microplate reader was used to perform spectrum scanning on each of 5 detection holes of common and ultraviolet(UV) microplates, and the applicable detection wavelength range was those with light transmittance greater than 80.00%. The optical density measurement was carried out on each 12 detection holes of common and UV microplates at different wavelengths, then the matching of the detection holes was compared. Potassium permanganate was quantitatively analyzed by common microplate and UV microplate, while acetone was analyzed by UV microplate, and then detection limit, lower limit of quantitation(LLQ), accuracy and precision at different loading volumes and concentrations were calculated and compared. RESULTS: The shortest applicable analyzing wavelengths for common and UV microplates were(362±2) and(230±3) nm respectively, while the longest applicable analyzing wavelengths were both 1 000 nm. The light transmittance of UV microplate was higher than that of common microplate when the analyzing wavelengths were lower than 400 nm(P<0.01). The deviation and range of light transmittance of detection holes analyzed by UV microplates were smaller than that of common microplates when the analyzing wavelengths were 350-1 000 nm(P<0.05). The detection limit and LLQ of potassium permanganate by multi-function microplate reader was not associated with the types of microplate. The adding standard recoveries of potassium permanganate by UV microplate was higher than that by common microplate(P<0.05). The adding standard recoveries of potassium permanganate by loading volumes of 200 and 250 μL was lower than that by loading volumes of 150 μL(P<0.01), while adding standard recovery of acetone by loading volumes of 200 μL was lower than that by loading volumes of 150 μL(P<0.05). CONCLUSION: When using a multi-function microplate reader to detect chemicals, it is recommended to use UV microplate with wavelengths at the range of 230-1 000 nm, and loading volumes of 200-250 μL.
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OBJECTIVE: To investigate the effect of 1,2-dichloroethane(1,2-DCE) acute inhalation exposure on the differential gene expression of phase Ⅰ metabolic enzymes. METHODS: The specific pathogen free SD rats were randomly divided into control group(16 rats), low-and high-dose groups(24 rats in each group, half males and half females). Low-and high-dose group were given daily 600, 1 800 mg/m~(3 ) of 1,2-DCE, and the control group given the fresh air by dynamic inhalation for 8 hours per day for consecutive 7 days. After the end of exposure, the relative mRNA expression of cytochrome P450 2 E1(CYP2 E1), alcohol dehydrogenase(ADH1) and acetaldehyde dehydrogenase 3 alpha 1(ALDH3α1) in the liver tissue was detected by real-time fluorescence quantitative polymerase chain reaction. RESULTS: The relative expression of CYP2 E1 in male high-dose group was higher than that in male low-dose group and female high-dose group(P<0.05). The relative expression of ADH1 in male low-and high-dose groups was higher than that in male control group(P<0.05). The relative expression of ADH1 in male high-dose group was higher than that in male low-dose group and female high-dose group(P<0.05). The relative expression of ALDH3α1 in high-dose group was higher than that in control group and low-dose group(P<0.05). CONCLUSION: High dose 1,2-DCE could increase the gene expression of phase Ⅰ metabolic enzymes in rat liver. The 1,2-DCE has more obvious effect in male rats than in female rats.
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OBJECTIVE: To investigate the effects of 1,2-dichloroethane(1,2-DCE) subacute exposure on depression in rats as well as the relevant mechanism of monoamine neurotransmitters. METHODS: The specific pathogen free male SD rats were randomly divided into control group, low-, medium-, and high-dose groups, with 10 rats in each group. The rats in these 4 groups were intra-gastrically administered with 1,2-DCE(diluted in corn oil) at the dose of 0, 20, 40, 80 mg/kg body weight, every other day for 14 times. After exposure, the behavior change of rats was observed by open-field test, sucrose preference test and forced swim test. The levels of the monoamine neurotransmitters including 5-hydroxytryptamine(5-HT), noradrenaline(NA) and dopamine(DA) in prefrontal cortex, hippocampus, and striatum of rats were analyzed by high performance liquid chromatography-electrochemical detection method. RESULTS: The number of rearing, time and distance of central area, sucrose preference index of mice in medium and high dose groups were decreased(P<0.05), while immobility time of forced swim test was increased(P<0.05) when compared with the mice in control group. The levels of 5-HT, NA and DA in prefrontal cortex, hippocampus, and striatum decreased with the increase of 1,2-DCE exposure(P<0.05), showing a dose-effect relationship. The levels of 5-HT, NA and DA in prefrontal cortex, hippocampus, and striatum in the high-dose group were lower than that of control group(P<0.05). CONCLUSION: The subacute exposure of 1,2-DCE can induce depression-like behavior in rats. The mechanism might be related to the reduction of monoamine neurotransmitters in striatum, hippocampus and prefrontal cortex.
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OBJECTIVE: To compare the effects of different anesthetics and blood sampling methods on blood routine test results in experimental animals. METHODS: A total of 42 specific pathogen free( SPF) male Sprague Dawley( SD) rats and 59 SPF male Kunming( KM) mice were randomly divided into 4 groups( control group,ether group,chloral hydrate group and pentobarbital sodium group). Ether group animals were treated with ether inhalation anesthesia; animals in chloral hydrate group and pentobarbital sodium group were injected intraperitoneally with chloral hydrate or pentobarbital sodium. The control group received no anesthesia treatment. Blood samples were collected by different ways: orbital venous plexus,abdominal aorta or eyeball enucleation. White blood cell( WBC) count,red blood cell( RBC) count,platelet(PLT) count,hemoglobin(Hb) level and hematocrit(HCT) in blood samples were analyzed. RESULTS: The RBC count,Hb level and HCT of SD rats in pentobarbital sodium group were significantly lower than those in control group( P <0. 05). The HCT of SD rats in ether group was lower than that in control group( P < 0. 05). The WBC count of orbital venous plexus of KM mice was lower than that taken by eyeball enucleation in control group( P < 0. 05),but the WBC count of orbital venous plexus was higher than that taken by eyeball enucleation in chloral hydrate group( P < 0. 05). The RBC count,Hb level,HCT of KM mice in pentobarbital sodium group were significantly lower than those in control group(P < 0. 05). CONCLUSION: The anesthetic can affect the blood routine test results of experimental animals. Different blood sampling methods have effects on blood routine test results of KM mice.
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OBJECTIVE: To investigate the effects of subacute systemic inhalation exposure of 1,2-dichloroethane(1,2-DCE) on learning and memory in NIH mice. METHODS: Forty-five specific pathogen free healthy 7-week-old NIH mice were randomly divided into control,low-dose and high-dose groups with 5 female mice and 10 male mice in each group. The mice were exposed to 1,2-DCE at dosages of 0. 00,100. 00 and 350. 00 mg/m3 for 6 hours per day for consecutive 28 days by dynamic systemic inhalation. The neurobehavioral tests of mice were performed before and after the first to fourth weeks of exposure using the Morris water maze test. RESULTS: There was no significant difference in body weight and swimming speed among the three groups of mice( P > 0. 05). The navigation experiment results showed that the escape latency of mice in both low-and high-dose groups were longer than that of the control group at the same time point(P < 0. 05) during 1-4 weeks after exposure. In the control group,the escape latency was shorter than that of the same group before exposure( P < 0. 05). The escape latency of high-dose group prolonged with the increase of exposure time,and in the 4 th week the escape latency was significantly higher than that of the same group before exposure( P < 0. 05).The experiment results of space exploration indicated that the first time of crossing platform in low-and high-dose groups were longer than that of the control group at the second to the fourth week( P < 0. 05). The target quadrant retention time and the number of crossing the platform in the low-and high-dose groups were lower than those in the control group( P <0. 05). CONCLUSION: Subacute inhalation exposure of 1,2-DCE can impair the learning and memory ability of NIH mice.The high-dose exposure may reduce learning ability in mice in a time-effect manner.
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OBJECTIVE: To explore the spontaneous non-tumor lesion of kidney and its correlation with different age and sex in SD rats. METHODS: Eight hundred specific pathogen free SD rats were collected from the blank control groups used in subacute toxicity tests,subchronic toxicity tests and 1 or 2 years of chronic toxicity combined with carcinogenic tests. Rats were randomly divided into 4 groups with 10,19,56 or 108 weeks of experimental periods. Each group consisted of 100 female and 100 male rats. The renal tissues were collected at the end of each experiment,and the renal organ coefficients were calculated. The pathological non-tumor changes of the kidneys were analyzed. RESULTS: The renal organ coefficients in female rats at the age of 56 and 108 weeks were both lower than that of 10 and 19 weeks( P < 0. 008). The renal organ coefficient of male rats at the age of 56 weeks was lower than that of 10 and 19 weeks( P < 0. 008). The renal organ coefficient of male rats at the age of 108 weeks was higher than that of 56 weeks( P < 0. 008). The renal organ coefficient of male rats at the age of 108 weeks was higher than that of female rats of 108 weeks( P < 0. 008). The incidence of renal tubular calcium salt deposition,interstitial inflammatory cell infiltration and renal tubular dilatation in the female rats at the age of 108 weeks were higher than those in the male rats at the age of 108 weeks( P < 0. 05). The chronic progressive nephropathy incidence of female rats at the age of 108 weeks was lower than that of male rats aged 108 weeks( P < 0. 01).The renal tubular calcium salt deposition incidence of female rats aged 56 weeks was higher than that of male rats aged 56weeks( P < 0. 01). CONCLUSION: The spontaneous non-tumor lesions in the kidney of SD rats were common. The incidence of some lesions was different in the same age group with different sex.
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OBJECTIVE: To explore the feasibility of dynamic observation and measurement of living silicosis rat model by using small animal positron emission tomography( PET)-computed tomography( CT). METHODS: Specific pathogens free SD rats were divided into model group and control group. The silicosis rat model was established by one-time endotracheal injection of 30 g/L silica suspension,while the control group rats were injected of isopyknic 0. 9% sodium chloride solution. Six rats from each group were randomly selected for CT scan from 1st,2nd,3rd,4th,6th,8th and 12 th week after silica injection using the small animal PET-CT. CT value and standardized uptake value( SUV) of18F-fluorodeoxyglucose were measured. Lung tissue was collected for pathological sections. The levels of hydroxyproline( HYP) of lung tissue and serum transforming growth factor β1( TGF-β1) and interleukin-1( IL-1) were measured.RESULTS: Pathological sections of rats of model group showed inflammatory exudation,inflammation reduced and fibrosis increased with extended time. The results are identical with findings in PET-CT. Lung SUV of rats in model group in the1st-3rd weeks were higher than that in control group in the same time point( P < 0. 05) and decreased by the increasing time during the 1st-4 th weeks of dust injection( P < 0. 05). Lung CT values of model group in the 1st-12 th weeks were higher than that of control group in the same 7 time points( P < 0. 05) and decreased in the 1st-6th weeks and then increased in the 6th-12th weeks by the increasing time of dust injection( P < 0. 05). Lung coefficients and HYP levels of model group in the 7 time points were higher than that of control group in the same 7 time points( P < 0. 05). Lung coefficients decreased in 1st-4th weeks and lung HYP levels increased in 6th-12th weeks with the increasing time of dust injection( P < 0. 05). Excepted of the 3rd and 4th weeks,serum TGF-β1 levels of model group in other 5 time-points were higher than that of control group in the same 5 time points( P < 0. 05) and decreased in the 1st-4th weeks( P < 0. 05)then increased in the 4th-8th weeks( P < 0. 05) by the increasing time of dust injection. Serum IL-1 levels of model group in the 1st-4th weeks were higher than that of control group in the same 4 time points( P < 0. 05) and decreased by the increasing time of dust injection( P < 0. 05) and decreased by the increasing time of dust injection( P < 0. 05).CONCLUSION: Early inflammation and terminal fibrosis of living silicosis rat model could be observed effectively by small animal PET-CT,which can be used as a new approach for dynamic tracing silicosis in rat models.
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OBJECTIVE: To explore the non-neoplastic hepatic lesions in SD rats at different ages. METHODS: The specificpathogen free SD rats were collected from the blank control groups used in subacute toxicity tests,subchronic toxicity tests and chronic toxicity combined with carcinogenic tests for safety evaluation. At the end of each experiment,i. e. week 10,19,56 and 108(assigned into four groups: 10,19,56 and 108 weeks,each contained 100 rats with each sex),rats were executed. The liver organ coefficient was calculated,the pathological examination was performed,and the non-tumorous lesions in the liver were analyzed. RESULTS: The liver organ coefficients at the age of 19,56,108 weeks were lower than that of 10 weeks(P < 0. 05); those at the age of 56 and 108 weeks were lower than that of 19 weeks(P < 0. 05),and that of 108 weeks was greater than of 56 weeks(P < 0. 05). Among the 10-week-old,19-week-old,56-week-old and 108-week-old groups,the types of non-neoplastic hepatic lesions detected in the female rats were 6,6,13 and 15 respectively,meanwhile those in the male rats were 6,6,13 and 15 respectively. Both male and female rats,the incidences of hepatocyte fatty degeneration,edema and hepatic infiltration of inflammatory cells were significantly increased with the increase of age in each group(P < 0. 05). The incidences of intrahepatic bile duct proliferation and intrahepatic bile duct fibrosis in rats at the age of 56 and 108 weeks were higher than those at the age of 10 and 19 weeks(P < 0. 008).Moreover,the frequency of hepatic sinus expansion lesions in rats at the age of 108 weeks was higher than those of 19 weeks(P < 0. 008). CONCLUSION: Spontaneous non-neoplastic lesions in the liver of SD rats were common,primarily demonstrated as hepatocyte fatty degeneration,edema and infiltration of inflammatory cells. The incidences of lesions increased with the increase of age.
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OBJECTIVE: To explore the intervening effects of bone marrow-derived mesenchymal stem cells(BMMSCs) for pulmonary fibrosis of rats exposed to silica dust at different stages. METHODS: Specific pathogen free SD rats were randomly divided into model group,2-week group,4-week group and control group with 6 rats in each group(half males and half females). Rats of the first three groups were one-time endotracheally injected with 0. 5 mL aseptic silica suspension at 30 g/L mass concentration. Rats of control group were injected with 0. 5 mL 0. 90% sodium chloride solution. Rats of 2-week group and 4-week group were injected with 0. 5 mL BMMSCs suspension with cell density was 5 × 10~9/L at 2 weeks and 4 weeks respectively after silica dust exposure,while model group and control group were injected with aseptic 0. 90% sodium chloride solution in the same volume. After that all rats were examined by lung computed tomography(CT) scan,pathological sections were observed,lung coefficient were measured,lung tissue hydroxyproline(HYP) content and serum transforming growth factor β1(TGF-β1) concentration were investigated at the 12 th week after silica dust exposure. RESULTS: Lung CT image showed clean lung field and clear pulmonary parenchyma in control group.Multiple and diffused high density granular shadows of different size and streak/reticular fiber shadows in model group;diffused distribution of very small granular shadows in 2-week group; granular shadows and local reticular fiber shadows in 4-week group,and either the size or the area of granular shadows was smaller than model group. The lung CT value,lung coefficient,lung tissue HYP content and serum TGF-β1 concentration of model group,2-week group and 4-week group were higher than those of control group(P < 0. 05). The lung CT value,lung tissue HYP content and serum TGF-β1 concentration of control group,2-week group,4-week group and model group were elevated in turn(P < 0. 05),while the lung coefficient of model group and 4-week group was higher than that of 2-week group respectively(P < 0. 05).CONCLUSION: BMMSCs could delay pulmonary fibrosis caused by silica dust,and the protective effect is better at early stage than later stage of fibrosis.