[The pulmonary toxicity study of nano-silica particles on rats through dynamic inhalation].
OBJECTIVE
To investigate the pulmonary toxicity of different concentrations of nano-silica (nano-SiO2) under continuous dynamic inhalation conditions in the rat.


METHODS
48 male Sprague-Dawley rats were randomly divided into four groups, including the dispersant control group (saline) and nano-SiO2 low-dose group (0.3%, w/v), the middle-dose group (1%) and the high-dose group (3%). Animals were sacrificed at 28 d after exposure under continuous dynamic inhalation conditions, and bronchoalveolar lavage fluid (BALF) and lung tissue were collected. And following items were observed: body coefficient, BALF related items (leukocytes and classification, total protein content, LDH activity), lung tissue pathological changes (HE staining), and pulmonary fibrosis forming (collagen fiber VG staining).


RESULTS
Compared to the dispersant control group, there was no significant change on lung organ coefficient in Nano-SiO2 group (P < 0.05). The BALF total WBC count in 1% and 3% in nano-SiO2 groups showed higher value than the dispersant control group (P < 0.05). No obvious changes were found on total protein content and LDH activity in nano-SiO2 groups compared to the dispersant control group (P > 0.05). For differential WBC counts, lymphocyte count in BALF in nano-SiO2 groups was significantly decreased (P < 0.05), monocyte and macrophage counts were significantly increased (P < 0.05), but there was no difference on the proportion of neutrophils (P > 0.05). HE staining results showed that the obvious thickening of alveolar wall in nano-SiO2 groups, inflammatory cell infiltration also increased around the bronchial and vascular wall. Lung fibrosis VG staining showed no significant change of collagen fiber distribution.


CONCLUSIONS
Under our experimental conditions, the continuous dynamic inhalation of nano-SiO2 only caused the significant inflammation in rat lungs, pulmonary fibrosis phenomenon could not be observed significantly.
Department of Toxicology, School of medicine, Zhejiang University. Hangzhou 310058, China.
Ping
P
Yang
Jun
J
Zhang
Yong
Y
Xia
Fei
F
Huang
Yu-ying
YY
Xu
Yi-fan
YF
Zheng
Jun
J
Yang
Xin-qiang
XQ
Zhu
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D019570:Inhalation Exposure; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D011658:Pulmonary Fibrosis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012822:Silicon Dioxide / Q000008:administration & dosage / Q000633:toxicity*
D012822:Silicon Dioxide