Morphological Changes of the Nasal Respiratory Epithelium of Mice Following Industrial Adhesive Vapor Inhalation

Song, Tae Hyun; Lee, Young Hoon; Han, Dong Yul; Kang, Ki Hoon; Kim, Dong Wook; Lee, Byung Don; Oh, Cheon Hwan; Chang, Hyuck Soon

Abstract

BACKGROUND AND OBJECTIVES: Social awareness of the narcotic effects of industrial adhesive vapors have been aroused by some teens who are reported to inhale these vapors to get the narcotic effects. When inhaled, the toxic effects of these chemicals are concentrated to the field of central nervous system, and the excretion system of metabolites like the liver and kidney. The effects of industrial adhesive vapors on the respiratory epithelium are unclear so far. MATERIALS AND METHOD: This was designed to study the morphological changes after exposure of the chemicals on the nasal mucosa in mice. Young healthy mice were exposed to industrial adhesive vapor (mixtures of acetone 5212+/-1268 ppm, c-hexane 3757+/-711 ppm, methyl cyclopentane 1820+/-375 ppm, n-hexane 139+/-30 ppm, toluene 0.9+/-1.4 ppm) for 20 min, once daily for 3 days, 5 days, 7 days, and 14 days. After adhesive vapor exposure, mice respiratory mucosa were excised, fixed in 4% paraformaldehyde for immuno-histochemistry and in 2.5% glutaraldehyde -1.5% paraformaldehyde for transmission electron microscopy and in 2.5% glutaraldehyde for scanning electron microscopy. Fixed tissues were processed for immunohistochemistry and for electron microscopy.
RESULTS
Cellular degeneration and necrosis were seen on exposure day 3 and 5 which included erosion or ulceration of epithelium, exfoliation of cell, deciliation, shrinkage of goblet cells etc. The architecture of ciliated columnar cells and goblet cells were regenerated on day 7. Among the ciliated cells, most of the cells were replaced by cuboid ciliated cells. And the secretory pattern of the goblet cells were also changed from the merocrine to apocrine type at same days of exposure. On the other hand, the PCNA immunochemical study revealed that positive cells were increased on day 5.
CONCLUSION
These results suggest that the nasal mucosa of mice can be damaged to some extent by daily regular exposure of industrial adhesive vapor. However, it could have a potency of regeneration to cuboidal cells, which are thought to change into more resistant cells in order to adapt to repetitive external stimuli.