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High-dose glucocorticoids inhibit proliferation of rat olfactory epithelium
Yasushi Ohta1, Minako Takanosawa, Chiori Matumoto
1Department of Otolaryngology-Head and Neck Surgery, Jichi Medical School, Tochigi, Japan.
Abstract:
Glucocorticoids (GCs) are commonly prescribed for treatment of olfactory dysfunction. However, the effects of GCs on olfactory epithelium are not well known. We investigated the effects of high-dose GCs on proliferating cells of olfactory epithelium. Five adult male rats (300 g) received a single daily subcutaneous dose of vehicle containing 0.3 mg dexamethasone (DEX) for 9 days (DEX+ group), and a control group received vehicle alone (DEX- group). We compared sections from the two groups for numbers of Ki67-positive cells. The mean number of Ki67-positive cells per 500 olfactory epithelial cells was 9.6 for the DEX+ group and 58 for the DEX- group (significant difference). We conclude that high-dose GC suppressed proliferation of olfactory epithelium. We suggest that high-dose GC suppresses cytokines and growth factors, resulting in secondary suppression of proliferating ability.
Insights
High-dose glucocorticoids (GCs) significantly suppress proliferation in the olfactory epithelium. This finding suggests GCs may impact the regenerative capacity of olfactory tissues.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- Glucocorticoids (GCs) are frequently used to treat olfactory dysfunction.
- The precise impact of GCs on the olfactory epithelium remains unclear.
- Understanding these effects is crucial for optimizing olfactory disorder treatments.
Purpose of the Study:
- To investigate the effects of high-dose dexamethasone (DEX) on cell proliferation within the olfactory epithelium.
- To quantify changes in Ki67-positive cells, a marker for cell proliferation, following GC administration.
Main Methods:
- Adult male rats were administered daily subcutaneous injections of either DEX or vehicle for nine days.
- Immunohistochemistry was used to identify and count Ki67-positive cells in olfactory epithelium sections.
- Quantitative comparisons were made between the DEX-treated group and the control group.
Main Results:
- A significant reduction in the number of Ki67-positive cells was observed in the DEX-treated group compared to the control group (9.6 vs. 58 per 500 cells).
- This indicates that high-dose GCs markedly suppress the proliferation of olfactory epithelial cells.
Conclusions:
- High-dose glucocorticoid administration inhibits the proliferation of olfactory epithelium.
- This suppression is potentially mediated by the downregulation of cytokines and growth factors, impacting cellular regenerative capabilities.