Histopathological Changes of Olfactory Epithelium in the Rats Exposed to Cigarette Smoke

Koo, Hyoung Joon; Lee, Hyun Sun; Cho, Kyu Sup; Park, Hee Young; Roh, Hwan Jung

Abstract

BACKGROUND AND OBJECTIVES: Although exposure to cigarette smoke has been reported to be associated with olfactory dysfunction, the pathophysiology is poorly understood. The purpose of this study is to evaluate the histopathological change of olfactory epithelium according to exposure duration of cigarette smoke and to investigate the effects of cigarette smoke on the olfactory epithelium.
SUBJECTS AND METHOD
Thirty-six healthy Sprague-Dawley rats were divided into 2 groups. Experimental groups (n=28) were exposed to cigarette smoke during 2.5 hours (total 5 cigarettes) per one day for 5 days, 11 days and 3, 4, 5, 6, 9 weeks. Control group (n=8) was placed at the same room without smoke exposure and sacrificed at 4 and 9 weeks. Histopathological changes of olfactory epithelium through light microscope and immunohistochemistric findings of olfactory marker protein (OMP) through confocal microscope were observed. The numbers of cells in olfactory epithelium were counted at each period.
RESULTS
From 5 days of cigarette smoke exposure, defection of epithelial cells, random arrangement of olfactory receptor cells and decreased thickness of olfactory epithelium were noticed. Numbers of olfactory receptor cells were significantly decreased at 11 days and 3 weeks after smoke exposure, and this finding of decreased number of olfactory receptor cells were continued until 9 weeks of exposure. Numbers of OMP-positive olfactory receptor cells were continuously decreased according to exposure duration.
CONCLUSION
The olfactory epithelial cells could be directly affected by cigarette smoke. The numbers of olfactory epithelial cells including olfactory receptor cells were continuously decreased until 9 weeks after cigarette smoke exposure.