Degeneration and regeneration of respiratory mucosa of rats after exposure to styrene

Abstract

The recovery process of pathological changes in the respiratory mucosa following exposure to styrene were experimentally studied to improve the understanding of the respiratory toxicity of styrene. Thirty male SD rats were exposed to 150 ppm or 1000 ppm of styrene for 4 h a day over 3 weeks (5 days a week). They were killed for examination at 1 day or 12 weeks after completion of the exposure sequence. Bilateral mucosal samples from the nasal septum and the trachea of the animals were examined for ciliary activity and subjected to electron microscopy. Complete functional and morphological recovery of the nasal and tracheal mucosa was observed at the 12th week post-exposure to 150 ppm of styrene. After exposure to 1000 ppm of styrene, almost normal function and morphology of the tracheal mucosa was found at the 12th week post-exposure, but the nasal mucosa continued to show decreased ciliary activity and an affected morphology.

Subchronic Inhalation Studies of Styrene in CD Rats and CD-1 Mice

“…In this study, histopathological changes, seen by light microscopy, were confined to the olfactory mucosa of rats exposed to 500-1000 ppm styrene; the respiratory mucosa was unaffected. In contrast, Ohashi et al (1986) found ultrastructural degenerative changes, by electron microscopy, in the respiratory epithelium of the nasal septum and trachea of rats exposed to 150 or 1000 ppm styrene over 3 weeks, with nasal respiratory epithelium being more sensitive than the trachea. Ohashi et al also found an associated reduction in ciliary activity at these sites with disablement of ciliary activity in the nasal septal mucosa following a 3-week exposure to 1000 ppm styrene.…”

Subchronic Inhalation Studies of Styrene in CD Rats and CD-1 Mice

“…the respiratory mucosa was unaffected. In contrast, Ohashi et al (1986) found ultrastructural degenerative changes, by After 2 weeks, the mean labeling index showed an increase from the control value of approximately threefold in mice electron microscopy, in the respiratory epithelium of the nasal septum and trachea of rats exposed to 150 or 1000 exposed to 150 ppm and fourfold in mice exposed to 200 ppm. After five weeks exposure, there were also increases ppm styrene over 3 weeks, with nasal respiratory epithelium being more sensitive than the trachea.…”

Exposure to styrene and mortality from nonmalignant respiratory diseases.

“…' In experiments with rats, morphological damage occurred after exposure to styrene in the upper, and to a less extent, in the lower respiratory tract. 2 Respiratory effects of styrene in rats are thought to be associated with gluthatione depletion in the lungs accompanied by inhibition of cytochrome P450 dependent oxidative drug metabolism. We examined mortality from non-malignant respiratory diseases in relation to exposure to styrene in a large international cohort study of workers in the glass reinforced plastics industry, where high workroom concentrations of styrene were encountered.…”