Morphologic alteration induced by short-term smoke exposure in rats.

BACKGROUND: It is a well-established fact that cigarette smoking causes degenerative, inflammatory, and respiratory diseases in humans. Because many factors such as air pollution and harsh working conditions can easily be eliminated in animal studies, we conducted this study to identify the effect of tobacco on rat trachea. METHODS: 24 male Wistar rats were divided randomly into an experimental and a control group. The experimental group of rats was exposed to cigarette smoke for 2 h each day over a duration of 60 consecutive days and the control group was treated in an identical fashion yet exposed only to room air. A morphometric study was performed on tracheal specimens taken from 22 rats (10 smoke-exposed rats and 12 control rats). RESULTS: Our results show that many of the morphological changes of the tracheal epithelium were found in the experimental group and significant quantitative differences were observed between the two groups. Loss of cilia, basal cell hyperplasia, goblet cell hyperplasia and an increased number of subepithelial inflammatory cells were observed by light microscopic examination of the trachea of experimental rats. We found very high levels of plasma thiocyanate after exposure to smoke in the experimental group, but no increase in the control group. CONCLUSIONS: The oxidants contained tobacco which could play an important role in the development of these structural and functional abnormalities in the trachea after smoke exposure. In addition, smoking can recruit inflammatory cells to the trachea.

Environmental tobacco smoke in rats.

OBJECTIVE: We conducted this study to identify the effect of subchronic cigarette smoke inhalation on the vocal cord mucosa of the rat. DESIGN: Experimental study. SETTING: Department of Otolaryngology, School of Medicine, Karadeniz Technical University, Trabzon, Turkey METHODS: Twenty-four male Wistar rats were divided randomly into experimental and control groups. The experimental group of rats was exposed to cigarette smoke for 2 hours each day over 60 consecutive days, and the control group was treated in an identical fashion but was exposed only to room air. MAIN OUTCOME MEASURES: Transmission electron microscopic examination of the rat vocal cords. RESULTS: We found very high levels of plasma thiocyanate after exposure to smoke in the experimental group but no increase in the control group. In the experimental group, mean plasma thiocyanate concentrations of 3.7 +/- 0.5 and 119 +/- 11.4 mmol/L were measured before and after exposure to tobacco smoke, respectively (p < .05). On the contrary, mean plasma thiocyanate levels of control rats were found to be 3.0 +/- 0.4 and 3.9 +/- 0.4 mmol/L, respectively, before and after exposure. In the experimental group, the epithelium covering the true vocal cords shows disturbed stratification. Some cells exhibit loss of desmosomal connections between cells and enlargement of the intercellular space. CONCLUSION: Our study demonstrates that the larynx in laboratory animals is one of the sensitive and useful targets for assessing the harmful effects associated with environmental tobacco smoke.