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R. M. Santo, N. Kara-Jose, P. Novaes, M. Matsuda, P. H. N. Saldiva, A. Berra; Effects of São Paulo Air Pollution on the Mice Conjunctiva. Invest. Ophthalmol. Vis. Sci. 2007;48(13):393.
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To evaluate the effects of prolonged exposure to ambient levels of air pollutants of São Paulo city on the mice conjunctiva.
Twenty-one male Swiss mice were maintained in two exposure chambers 24 h/day, 7 days/week, for 2 months. One of the chambers received ambient air at a flow rate of 50 L/min (polluted chamber, 13 animals), whereas the other (control), maintained in the same location, received filtered air (clean chamber, 8 animals) with the same flow rate. Inside the chambers the animals were kept under the same conditions of temperature and humidity. At the end of the exposure, mice were euthanized and the orbits exenterated. After fixation in 10% buffered formalin, the materials were sectioned in a way to permit evaluation of the ocular surface epithelium (right eyes were sectioned to analyze nasal conjunctiva and left eyes to evaluate temporal conjunctiva) and included in paraffin blocks. Periodic acid Schiff (PAS) technique was used to show conjunctival goblet cells. The linear distance between the cutaneous-mucosal transition and mucosecretory epithelium (goblet cells) was measured (non-secretory epithelium length). The intraepithelial mucosubstance was quantified using conventional morphometry.
We did not find significant difference in the proportion of non-secretory epithelium between the two groups. However there was an increase in the proportion of intraepithelial mucosubstance in the polluted chamber that was even more significant when we considered the temporal conjunctiva (clean = 5.00 ± 1.51 µm2/µm; polluted = 6.02 ± 2.79 µm2/µm; p = 0.027) (Fig.1).
Our results show that prolonged exposure to low levels of ambient air pollution from an early age leads to phenotypic changes of the mice conjunctiva and suggest that temporal conjunctival epithelium may undergo an adaptation process by increasing its production of mucosubstance when challenged by environmental agents.
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