Formaldehyde Gas Induced Morphological Changes in the Rat Olfactory Epithelium

Baek, Sun Yong; Jeon, Jae Ki; Moon, Yong Suk; Hwang, Seung Young; Roh, Hwan Jung; Goh, Eui Kyung; Wang, Soo Geun; Chon, Kyong Myong; Kim, Bong Seon; Kim, Jae Bong; Kim, Jin Jeong

Abstract

Experimental animals were inhalated 50 ppm formaldehyde gas for 3 times with one hour exposure and one hour rest. The olfactory mucosa were taken from the animals on 4, 7, 9, 11 days and 2-6 weeks after the inhalation. The characteristics of the various glycoproteins and the mitotic activity of the olfactory epithelial cells were investigated using lectins and 5'-bromodeoxyuridine (BrdU, 50 mg/kg) which injected one hour before sacrifice of the animals. The results were as follows; 1. In experimental animals, the degenerative changes of the olfactory epithelium such as atrophy and squamous metaplasia were observed until 2 weeks after formaldehyde gas inhalation. 2. In control animals, positive reactions appeared in the supporting cell to PNA, SBA, WGA, ECL, PHA-L and in the olfactory cells to PNA, SBA, WGA, UEA and in the proper basal cell to GS-I, SBA, WGA, PHA-L. In experimental groups, the positive reaction was increased in the supporting cells to SBA, ECL, PHA-L and in Bowman's gland to used lectins except ECL, GS-I. 3. The number of BrdU labelled cells in the olfactory epithelium was 14.8+/-1.2/mm in the control animals. The mitotic activities were decreased to 4.8+/-0.8 mm in 2 weeks and recovered in 3 weeks after the gas inhalation. 4. To find the stem cells of olfactory receptor cells, double labelling method was performed with lectins which were specific for proper basal cells (GS-I or PHA-L) and BrdU immunohistochemistry. The ratio of globose/proper basal cells in BrdU labelled cells with GS-I lectin positive reaction was 82%/18% in control group, 39.3%/60.7% in lesion group and 55.5%/44.5% in recovery group.