Objective To establish a rat silicosis model by a dynamic silica dust exposure control system.
Methods Forty SD rats were randomly divided into control group, and 1 d, 3 d, 7 d, 2-week, 4-week, 8-week, and 12-week groups, 5 rats for each group. The rats were exposed to silica dust for 2 h a day in a dynamic control system at the concentration of 170-190 mg/m3. After the exposure, the animals were sacrificed according to the assigned group and the control group rats did after 12 weeks. The body weight and lung weight were recorded to calculate lung/body coefficients. Hydroxy proline (Hyp) in the lung tissue was detected and pathological changes were observed.
Results The concentration of silica dust in the exposure chamber was maintained stable. The lung coefficient gradually increased with the time of exposure. Mild congestion and edema were observed in the lung tissue in the 1 d group; inflammatory cells around blood vessels were recorded in the 7 d group, most of them were monocytes and lymphocytes. In the 2-week group, red dye and foam cells were found in the alveoli. In the 4-week group, dropped-off alveolar epithelial cells, phagocytes-formed nodules, and a small amount of fibrous tissue hyperplasia were identified. In the 8-week group, more fibrous hyperplasia were observed, plus the gland-like hyperplasia of type II alveolar epithelial cells. Fibrous nodules appeared in the 12-week group, and no abnormality in lung was identified in the control group. The level of Hyp in the lung tissue increased gradually along with the exposure duration to silica dust.
Conclusion The rats silicosis model could be well established by the dynamic control system.
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