Effect of polymerized toner on rat lung in chronic inhalation study

Autor:	Hiroshi Kasai, Takahiko Kasai, Masahiro Murakami, Makoto Yamamoto, Yasuo Morimoto, Kazuaki Kawai, Kenichiro Nishi, Toshihiko Myojo, Isamu Tanaka, Takako Oyabu, Akira Ogami, Masami Hirohashi, Chikara Kadoya, Motoi Todoroki
Rok vydání:	2009
Předmět:	Pathology medicine.medical_specialty DNA Complementary Polymers Health Toxicology and Mutagenesis Toxicology Collagen Type I Fibrosis Internal medicine medicine Animals Rats Wistar Lung Inhalation exposure High concentration Inhalation Exposure Tissue Inhibitor of Metalloproteinase-2 Inhalation Reverse Transcriptase Polymerase Chain Reaction Chemistry Deoxyguanosine Organ Size medicine.disease Survival Analysis Rats Endocrinology medicine.anatomical_structure 8-Hydroxy-2'-Deoxyguanosine Exposure period Chronic Disease Matrix Metalloproteinase 2 RNA Exposure chamber Female Ink Type I collagen
Zdroj:	Inhalation Toxicology. 21:898-905
ISSN:	1091-7691 0895-8378
DOI:	10.1080/08958370802641938
Popis:	In order to evaluate the chronic effect of polymerized toner particles on the lung, inflammation- and fibrosis-related genes were analyzed and 8-hydroxydeoxyguanosine (8-OHdG) was examined by using the lung tissue of rats subjected to 24 months of toner inhalation exposure. Wistar female rats were divided into four groups (5 weeks old, 30 rats in each): the high concentration exposure group (16.3 +/- 0.6 mg/m(3)), the medium concentration exposure group (4.4 +/- 0.3 mg/m(3)), the low concentration exposure group (1.6 +/- 0.2 mg/m(3)), and the control group (clean air). The material used was black toner, and its aerodynamic diameter in the exposure chamber was 3.0 microm. The rats were exposed to the material for 24 months (6 hours/day, 5 days/week) and dissected after the exposure period. RNA was extracted from one lung and the gene expression related to inflammation and fibrosis. Matrix metalloproteinase-2 (MMP-2), tissue inhibitor of metalloproteinase-2 (TIMP-2), and type I collagen were analyzed according to the ratio of each gene/beta-actin. Also, 8-OHdG level in the lung tissue was measured by HPLC with an electrochemical detector. Small fibrotic foci were found in the toner exposed groups; however, progressive or irreversible fibrosis was not found. The incidence of small fibrotic foci and cell aggregation increased in a dose-dependent manner. There were no significant differences of expression of MMP-2, TIMP-2, and type I collagen between the control group and each exposed group. Lung tumors did not develop in each group. A significant production of 8-OHdG was not observed in the toner exposed groups. In conclusion, toner produced by polymerization was not associated with evidence of carcinogenesis in this experiment.
Databáze:	OpenAIRE
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