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OBJECTIVE: To obtain information on the toxicity of lufenuron on the reproduction ability and the growth and development of offspring in female and male rats through two-generation reproduction toxicity study. METHODS: The specific pathogen free healthy SD rats were randomly divided into control group and low-, medium-and high-dose lufenuron groups, with 60 rats in each group, half females and half males. Rats in the low-, medium-and high-dose lufenuron groups were respectively fed with lufenuron at the dose of 5.0, 20.0 and 80.0 mg/(kg body weight·day) for 8 weeks before mating. The control group was fed with standard foot. The reproductive index, brain and reproductive organ coefficients and pathological changes were observed in P and F1 parents. The birth and growth indexes of the offspring were measured. RESULTS: i) P generation: from the 14 th day, the female rats in the medium-dose group had lower body weight than that of the female control group(P<0.05); from the 35 th day, the body weight was lower than that of the female low-dose group(P<0.05). From the 14 th day, the female rats in the high-dose group had lower body weight than that of the other three female groups(P<0.05). From the 14 th day, the male rats in the medium-and high-dose groups had lower body weight than that of the male control group and low-dose group(P<0.05). The body weight of pregnant rats in the parental high-dose group was lower than that of the control group, low-dose group, and medium-dose group at day 0, 7, 14, 19 of the pregnancy duration(P<0.05). The body weight of pregnant rats in the parental medium-dose group was lower than that of the low-dose group on day 0 of the pregnancy duration, and lower than that of the control and low-dose groups on day 7 and 14(P<0.05). The conception rate, the new-borne survival rates and the feeding survival rate of female rats in the high-dose group was lower than that of the other three female groups(P<0.008). The new-borne feeding survival rate of female rats in the medium-dose group was lower than that of the control group and low-dose group(P<0.008). The organ coefficients of brain in female rats in the medium-and high-dose groups were higher than that of the female control group and low-dose group(P<0.05). The organ coefficients of brain and testis in male rats in the medium-and high-dose groups were higher than that of the control group and low-dose group(P<0.05). The organ coefficient of epididymis in male rats in the high dose group was lower than that of the other three male groups(P<0.05). ii) F1 generation: the body weight of female rats in the low-and medium-dose group was higher than that of the female control group on the 42 th day(P<0.05). The body weight of male rats in the low-dose group was higher than that of the male control group on the 42 th, 49 th, and 56 th days(P<0.05). The body weight of male rats in the medium-dose group was higher than that of the male control group on the 14 th, 21 th, 42 th, 49 th, and 56 th days(P<0.05). The new-borne survival rate in the low-dose group was lower than that of the control group(P<0.017). The body weight of new-borne rats in the high-dose group on day 4 of birth was lower than that in the other three female groups(P<0.05). iii) F2 generation: the body weight of male rats in the male medium-dose group was lower than that in the control group on day 21 of birth(P<0.05). CONCLUSION: The reproductive and developmental toxicity of lufenuron is found in rats in the medium-and high-dose groups. Toxicities including low body weight, conception rate, new-borne survival rate and feeding survival rate are found in P generation; low body weight and feeding survival rate are found in F1 generation; low body weight is found in male F2 generation. The no-observed-adverse-effects levels of lufenuron in two-generation reproductive study are 5.87 mg/(kg·d) for females and 5.09 mg/(kg·d) for males in SD rats.
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OBJECTIVE: To observe the pathological changes of rat silicosis model at different time points. METHODS: The specific pathogen free SD rats were randomly divided into control group and 7, 15, 21, 30, 45, 60, 75 and 90 day model groups based on their body weight, with 5 rats in each group. Non-exposed endotracheal intubation was performed. Silicosis rat model was established by intratracheal instillation of 250 g/L silica suspension in each rat, and 0.9% sodium chloride solution was perfused into the trachea of rats in the control group. The rats in the control group were sacrificed on the 90 th day after exposure, and the model rats in the other 8 groups were sacrificed on the 7 th, 15 th, 21 st, 30 th, 45 th, 60 th, 75 th and 90 th days after the end of exposure. The gross appearance of the lung tissue of rats was observed. The rat lung tissues were stained with hematoxylin-eosin and Masson staining to observe the pathological changes, and Ashcroft score was evaluated. RESULTS: The gross observation showed that the lungs of rats in the model groups had varying degree of gray changes, hardened texture, and spots and nodules on the surface of the lobes. These changes were aggravated with the increase of time after dust exposure. The results of histopathological examination of the lungs showed that the rats developed acute alveolar inflammation, and a large number of macrophages and neutrophils were seen in the lung tissues in the 7 th and 15 th day model groups. Cellular nodules appeared in the lung tissue, and fibrosis appeared in the center of the nodule in the rats of 21 st, 30 th, and the 45 th day model groups; the silicosis nodules appeared in the lung tissues of rats in the 60 th, 75 th, and 90 th day model groups, and the small nodules gradually merged into larger ones. Simultaneously, with the increase of time after dust exposure, the lung tissue of rats gradually showed severe pulmonary fibrosis. The lung organ coefficient and Aschcroft score of rats increased with the increase of time after dust exposure(P<0.01). CONCLUSION: The rat lung changes after dust exposure. Acute alveolar inflammation occurs on the 7 th to 15 th day after dust exposure; cellular nodules develop on the 21 st to 45 th day after dust exposure; silicosis nodules develop on the 60 th to 90 th day after dust exposure. The severity of lung fibrosis after dust exposure showed a time-effect relationship in rats.
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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 explore the chronic toxicity and carcinogenicity of paclobutrazol in SD rats. METHODS: Specific pathogen free SD rats at the age of weaning were randomly divided into control group and low-,medium-,and high-dose groups according the body weight,with 120 rats in each group,half male and half female. The study of combined chronic toxicity and carcinogenicity test in rats was carried out in 2 years by feeding the rats with paclobutrazol. The doses in the 4 groups were 0. 0,11. 7,48. 5 and 193. 9 mg·kg~(-1)·d~(-1) for female rats and 0. 0,13. 5,54. 2 and 241. 9 mg·kg~(-1)·d~(-1) for male rats. The body weight of rats was weighted during the experiment. The blood routine,blood biochemistry,organ coefficient and histopathology examinations were performed at the end of paclobutrazol exposure. The mortality and tumor incidence in rats were calculated. RESULTS: The decrease of body weights in female and male rats in dose groups was observed at 1-2 weeks after the experiment,compared with the same sex control group at the same time point( P < 0. 05).At the end of the exposure,the body weights of female and male rats in all three dose groups were lower than that in the same sex rats of control group( P < 0. 05). The mortality rates of female and male rats in the four groups were not significantly different( P > 0. 05). The brain organ coefficients of female rats in the three dose groups were higher than those female rats in the control group( P < 0. 05). The organ coefficients of liver,kidney and ovary of female rats in highdose group were higher than that of female rats in control group( P < 0. 05). The level of total bilirubin in male rats in the three dose groups was lower than that in control group( P < 0. 05). The organ coefficients of brain and lung in male rats in the medium-and high-dose groups were higher than that in the control group( P < 0. 05). The liver organ coefficient in male rats in the high-dose group was higher than that in the control group( P < 0. 05). A total of 244 rats had 402 spontaneous tumors with a tumor incidence rate of 50. 8%(244/480). The incidence of tumor in control,low-,mediumand high-dose groups were 61. 7%( 74/120), 42. 5%( 51/120), 50. 0%( 60/120) and 49. 2%( 59/120)respectively. There was no statistical significance in the incidence of tumors in three dose groups compared with that of the control group. CONCLUSION: Under the dose conditions designed in this study,the lowest observed adverse effect level of paclobutrazol were 11. 7 and 13. 5 mg · kg~(-1)· d~(-1) in females and males respectively. Paclobutrazol was not found carcinogenic to SD rats.
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OBJECTIVE: To explore the molecular mechanism underlying 1,2-dichloroethane(1,2-DCE) induced apoptosis by screening differentially expressed proteins in human astrocytes( HAs). METHODS: HAs were cultured in complete medium with 1,2-DCE at various concentrations of 0-80 or 0-40 mmol/L. After 24 hours,apoptosis of HAs was evaluated using flow cytometry and staining with annexin Ⅴ-fluoresce in isothiocyanate and propidium iodide. An AAH-APO-1-2 protein chip was used to screen differentially expressed proteins and quantitative real-time polymease chain reaction(qRT-PCR) was used to verify related differentially expressed genes(DEGs). RESULTS: At 1,2-DCE concentrations of0-80 mmol/L,the total apoptosis rate of HAs increased with 1,2-DCE concentrations in a dose-dependent manner( P <0. 01). Seven different kinds of proteins were screened out by apoptotic protein chip. Among them,the expression of insulin-like growth factor-binding protein( IGFBP)-1,IGFBP-4 and cytochrome C( Cyto C) were up-regulated,while the expression of P27,cysteine aspartic acid specific protease-3( Caspase-3),B-cell lymphoma-2 interacting mediator of cell death( BIM) and BH3 interacting domain death agonist( BID) were down-regulated compared with the control group. The result of DEGs verified by qRT-PCR showed that the expression of mRNA of IGFBP-1,IGFBP-4 and Cyto C at 1,2-DCE concentrations of 40 mmol/L was up-regulated. This result was in consistent with the trend of target expression in the protein chip. The mRNA expression of Caspase-3,BIM and BID was also up-regulated. CONCLUSION: 1,2-DCE induces apoptosis of HAs through mitochondrial pathway.
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OBJECTIVE: To predict the sensitizing potency and optimal sensitization dose of trichloroethylene( TCE) by an in vitro skin sensitization test on a human acute monocytosis cell line( THP-1).METHODS: THP-1 cells were cultured in vitro and exposed to 2,4-dinitrochlorobenzene( DNCB),sodium dodecyl sulfate( SDS),tert-butylhydroquinone( tBHQ)and TCE for 24 hours.Flow cytometry was used to detect the expression of cell surface marker such as cluster of differentiation( CD) 86 and CD54,and the optimal dose range for sensitization detection was determined.With the relative fluorescence intensity( RFI),CD86 ≥ 150 and CD54 ≥ 200 as the standard,the sensitizing potency and optimal sensitization dose of TCE were predicted.RESULTS: The concentration range of reagents for sensitization test on THP-1 cells was the dose range at which the relative cell survival rate reached 75.0%-100.0%.DNCB at the doses of 20.83,25.00 and 30.00 μmol/L,tBHQ at the dose of 5.80 μmol/L,TCE at the doses of 8.33,10.00 and 12.00 mmol/L,can cause sensitivity.SDS was recognized as a negative sensitizer.The expression of CD86 and CD54 was the highest when the concentration of TCE was 8.33 mmol/L,which was considered as the best sensitization dose.CONCLUSION: The optimum sensitization dose of TCE is 8.33 mmol/L,which can provide the basis for dose design in future study of TCE sensitization pathways.
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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 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.