| Objective To investigate the toxic mechanism of Chrysotile asbestos and its artificial substitute fibers from the perspective of tumor gene by Intratracheal instillation and make scientific basis for safety evaluation of chrysotile asbestos and its artificial substitute fibersMethods 90 male Wistar rats were respectively assigned to 5 groups(AKesai chrysotile group;ceramic fibre group;galss fiber group;rock wool group;saline group;and administered by intratracheal instillation for 2.0mg/ml of chrysotile(Akesai)and artificial substitute fibers(ceramic fibre;galss fiber;rock wool;)dissolved in saline,and the negative control group was treated with saline as the same way,repeated once a month for 6 month with 0.5m1.When wistar rats were exposed to 1month,3months,6months,the pathological changes of the rats lung tissue were observed by HE staining,while using real-time PCR quantified p53,p16,c-jun,c-fos mRNA expression.Western blot method to measure lung tissue P53,P16,C-Jun,C-Fos protein expression.Result(1)Compared with the control group,the Rats’ weight in ceramic fibre group,galss fiber group and rock wool group grow slowly after exposed to fiber 3 months and the lung weight were highter than negative control group(P<0.05).(2)With the increasing of exposure time,the expermental groups’ lung tissue have a severity of appearance damage.HE staining showed that in each exposure group,inflammatory cell aggregation,alveolar structure destruction and fibrosis were observed to varying degrees,and the injury increased with the prolongation of exposure time.(3)The results of real time PCR showed that,after exposed fiber 3months,the expermental groups’ p53 mRNA level are lower than control group and the ceramic group had the most significant decrease(P<0.05);The level of mRNA expression of tumor suppressor gene p16 was significantly lower in each exposure group than that in negative control group after 6 months of exposure(P<0.05);The expression of c-jun mRNA was significantly higher in each exposure group than that in negative control group after 6 months of exposure,especially in Akesai chrysotile exposure group(P<0.05).The expression of cfos mRNA was higher in each group than that in negative control group after 3 months of exposure,and the level of cfos in chrysotile asbestos-exposed group increased most significantly after exposure for 6 months(P<0.05).(4)The results of Western blot showed that the expression of P53 protein was lower in each group than in the negative control group after 3 months of exposure,and the level of P53 protein in ceramic group was the most significantly lower than that in the control group(P<0.05).After 6 months of exposure,the expression of P16 protein in each group was lower than that in negative control group,and the ceramic group decreased most obviously(P<0.05).The expression of C-Jun protein was higher in each exposure group than that in negative control group after 3 months of exposure.The C-Jun protein expression was most significant in Akesai chrysotile exposure group after 6 months of exposure(P<0.05).The expression level of C-Fos protein in each exposure group was higher than that in negative control group after 3 months of exposure,and the upregulation of C-Fos protein expression was most significant in Akesai chrysotile exposure group after 6 months of exposure to chrysotile asbestos(P<0.05).Conclusion Chronic exposure to chrysotile and its artificial substitute fibers by intratracheal instillation could cause changes in body weight and lung weight of rats.Chrysotile and its artificial fiber enter the lungs of Wistar rats,which can cause morphological and pathological changes in the lungs of rats,and the more serious the damage is,the longer the time of exposure.Chrysotile and its artificial substitute fibers can induce the changes of mRNA expression and protein expression of lung tumor-associated genes in wistar rats.The effect of chrysotile and its artificial substitutes on the expression of related genes in lung tumor of rats is different. |
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