Lipopolysaccharide-induced apoptosis of olfactory receptor neurons in rats.

Conclusion: Daily intranasal perfusion of lipopolysaccharide (LPS) for 14 days in rats induced apoptosis of olfactory receptor neurons (ORNs) over >3 but <7 days.

Objectives: Smoking is one of the factors causing olfactory dysfunction. LPS is a major glycolipid component of the gram-negative bacterial cell wall and an active component of cigarette smoke. We studied whether LPS is one of the causes of tobacco-induced olfactory dysfunction by examining apoptosis in the olfactory epithelium after local exposure to LPS.

Materials And Methods: Rats received intranasal instillation of LPS or saline. Histochemical changes in the olfactory epithelium were examined using antibodies against single-stranded DNA, Bcl-2, Bax, and Caspase-3. We used different concentrations of LPS to examine the dose dependency and observed changes in the olfactory epithelium for a week after exposure cessation to see the duration of the effect of smoking.

Results: We found that numbers of cells positive for ssDNA, Bcl-2, Bax, and Caspase-3 were increased on the exposed side. The number of ssDNA-positive cells reached a maximum on the first day and decreased to normal levels on the seventh day after cessation of exposure.