Abstract

Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. We have earlier reported that long term dietary exposures to fipronil cause lung inflammation. Endotoxins are frequently prevalent among agricultural settings and have also been associated with lung damage. However, the mechanism of fipronil induced lung damage with or without endotoxin remains to be elucidated. The present investigations included male Swiss albino mice (N=36) aging 6-8 weeks to estimate catalase expression in lung and serum following exposure to fipronil with or without LPS. Animals were divided into two treatments and one control group (N=12, each). Treatment groups were orally administered high (1/10th of LD50) and low (1/20th of LD50) dose of fipronil dissolved in corn oil for 90 days followed by LPS (80 μl/animal) or NSS challenge via intranasal route. Low dose of fipronil along with LPS resulted 3.75 folds increase in the mRNA expression of catalase in the lung. High and low dose of fipronil alone or in combination with LPS showed strong immunopositive reactivity for catalase in the airways and bronchial epithelial cells. There was a significant increase in the number of immunopositive cells for catalase following exposure to individual high or low dose of fipronil or in combination with LPS as compared to control and LPS group. High dose of fipronil significantly (p<0.05) increased the protein concentration of catalase as compared to control group suggesting dose dependent dysregulation of catalase in serum. The data taken together suggest that exposures to fipronil with or without LPS altered the pulmonary expression of key genes associated with oxidative stress.