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Vol. 41 No. 1, 2002
Morphological Alterations in the Trachea of Capsaicin-pretreated Rat during Postnatal Development
Shang-Ming Yu1,* and Kwan-Hwa Lin2
1Institute of Anatomy and Cell Biology, School of Life Science, National Yang-Ming University, Taipei, Taiwan 112
2School of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan 100
Shang-Ming Yu and Kwan-Hwa Lin (2002)
The purpose of this study was to investigate morphological changes of
the mucosa layer of the trachea in rats pretreated with capsaicin
neonatally. Paraformaldehyde-lysine-periodate- and osmium-fixed plastic
sections were prepared from 17 capsaicin pretreated rats and 15
controls and studied at the light microscopic level. The results
indicate that no significant differences occurred in the mean
cross-sectional epithelial thickness of the tracheal mucosa between 1
wk after neonatal capsaicin treatment (20.40 ± 0.48 µm) and sham
treatment (21.80 ± 0.80 µm). Cross-sectional epithelial thickness
(18.81 ± 0.39 µm) continued to show no significant difference through 2
wk after neonatal capsaicin treatment, but the epithelial thickness
significantly (p < 0.05)
increased at 2 wk after sham treatment (40.05 ± 1.80 µm). Furthermore,
cross-sectional epithelial thickness also significantly (p
< 0.05) increased at 1 mo after sham treatment (41.24 ± 1.20 µm)
compared to that with neonatal capsaicin treatment (24.79 ± 0.54 µm).
At the light microscopic level, large vacuoles were strikingly
prominent in the tracheal epithelium at 1 wk after neonatal capsaicin
treatment, as were many small vacuoles at 2 wk. Another striking change
was that apical cytoplasmic blebbing of goblet cells had increased
moderately at 2 wk after neonatal capsaicin treatment and had increased
markedly at 1 mo. Substance P-like immunoreactivity (IR) was not
discernible at 1 wk after sham or capsaicin treatment. Substance P-like
IR was slightly immunolabeled at 2 wk and increased markedly at 1 mo
after sham treatment. In contrast, substance P-like IR was not
immunolabeled at either 2 wk or 1 mo after neonatal capsaicin
treatment. The present study suggests that neonatal capsaicin treatment
results in epidermal thinning of the trachea during postnatal
development. The blockade of the elastic fibers containing substance
P-like IR implies involvement of the elastic fibers in the histologic
response to capsaicin's effect on the depletion of substance P.
Moreover, formation of apical cytoplasmic blebbing of goblet cells
indicates hindrance by capsaicin of mucus secretion and clearance.
Key words: Capsaicin, Immunocytochemistry, Postnatal development, Substance P, Trachea.
*Correspondence: Tel: 886-2-28267071. Fax: 886-2-28212884. E-mail: smy@ym.edu.tw
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