Effects of Chronic Nicotine Administration on Salivary Gland in Mice: Immunohistochemical Study

Abstract

Purpose: Chronic nicotine administration induce various effects in whole organs of the body; however, little is known about salivary gland. In the present study, we pursued the links be-tween systemic nicotine and the histomorphological changes of the salivary gland in mice. Methods: Twenty-five C57BL6 mice were allocated into two groups. The control group (n=9) received distilled water only for 8 weeks by gavage. The experimental nicotine group (n=16) was administered nicotine 5 μg/g with distilled water. Animals were sacrificed at 8 weeks; then, submandibular glands were excised and processed for histologic evaluation. Volumetric changes in acinar cells were evaluated by H&E staining. The expression of calponin-positive myoepithelial cells and Ki-67-positive proliferating acinar cells were evaluated by immunohis-tochemistry. Results: The nicotine group showed significantly decreased number of calponin-positive myo-epithelial cell process compared with the control group. There were no significant differences in average volume of acinar cell and the number of Ki-67-positive acinar cells between both groups. Conclusions: These findings suggested that chronic nicotine administration may cause de-creased function of myoepithelial cells in submandibular glands of mice, and these can partly explain xerostomic conditions in chronic smokers. into the blood flow through the lung, oral mucosa, skin and intestine, and then moves into cardiovascular, endocrine, musculoskeletal system as well as peripheral and central nervous systems. 4) Absorbed nicotine can cause tempo-ral elevation of blood pressure, pulse rate and nausia, xe-rostomia, and euphoria by activating mesolimbic system. However, repetitive nicotine administration gradually de-creases the sensitivity of nicotinic acethylcholine receptor. Thereby it causes the addiction to nicotine which makes the chronicity of smoking. 5) There are several studies about the relevance between chronic nicotine intake and secretory impairment such as pancreatitis. 6-8) Short-term nicotine administration can induce the elevated Ca 2+ influx in pancreatic acinar cell which activates secretion in acinar cell. 6) However, chronic