Cancer Res Treat.  2009 Sep;41(3):145-154.

Apoptosis and Expression of AQP5 and TGF-beta in the Irradiated Rat Submandibular Gland

• Choi JH
• Wu HG
• Jung KC
• Lee SH
• Kwon EK

Abstract

PURPOSE
To evaluate the effect of X-ray irradiation on apoptosis and change of expression of aquaporin 5 (AQP5) and transforming growth factor-beta(TGF-beta) in the rat submandibular gland (SMG). MATERIALS AND METHODS: SMGs of 120 male Sprague-Dawley rats were irradiated with a single X-ray dose (3, 10, 20, or 30 Gy). At the early and late post-irradiation phase, apoptosis was measured by the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) method, and expression of AQP5 and TGF-beta was determined by immunohistochemical staining. RESULTS: At the late post-irradiation phase, increased apoptosis was evident and marked decreases of expression of AQP5 expression by acinar cells and TGF-beta expression by ductal cells were evident. CONCLUSION: Apoptosis after X-ray irradiation develops relatively late in rat SMG. Irradiation reduces AQP5 and TGF-beta expression in different SMG cell types.

Keyword

Submandibular gland; Radiation; Apoptosis; AQP5; TGF-beta

MeSH Terms

Acinar Cells
Animals
Apoptosis
Aquaporin 5
DNA Nucleotidylexotransferase
Humans
Male
Rats
Rats, Sprague-Dawley
Submandibular Gland
Transforming Growth Factor beta
Aquaporin 5
DNA Nucleotidylexotransferase
Transforming Growth Factor beta

Figure

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  Fig. 1 Radiation-induced morphological changes in rat SMG. (A) Nonirradiated gland. The SMG parenchyma is composed mainly of acinar cells and duct cells. (a) Acini, (c) Granular convoluted tubules. (B) Day 3 after irradiation with 10 Gy. Increased numbers of cytoplasmic vacuoles (⇒) in acinar cells were found. (C) Day 60 after irradiation with 10 Gy. Numbers of GCT and SD cells were degenerated and the cells desquamated (→), and some duct cells were dissolved. Sections were stained with H & E. Magnification is ×400.

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  Fig. 2 Morphometrical change in GCT cells of irradiated rats at the late post-irradiation phase. *Statistically significant difference from sham-treated control (p<0.05).

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  Fig. 3 Apoptosis in submandibular gland of irradiated rats. (A) TUNEL assays in non-irradiated gland (a) and day 3 (b), day 10 (c), and day 30 (d) after irradiation with 10 Gy. (B) Time course of the percentage of apoptotic cells (%) in submandibular gland of irradiated rats. *Statistically significant difference from sham-treated control (p<0.05) (C) The finding in transmission electron microscopy. The apoptotic cells with nuclear chromatin condensation (⇒) and margination (←) were observed at day 30 and 60 after irradiation. Magnification is ×400.

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  Fig. 4 Altered AQP5 and TGF-β expression in irradiated rats. (A) Immunohistochemical staining of AQP5 in non-irradiated gland (a) and day 3 (b), day 10 (c), and day 30 (d) after irradiation with 10 Gy. A loss of AQP5 expression of acinar cells was observed at the late post irradiation phase. (B) Immunohistochemical staining of TGF-β in nonirradiated gland (a) and day 3 (b), day 10 (c), and day 30 (d) after irradiation with 10 Gy. A loss of TGF-β expression of ductal cells was observed at the late post irradiation phase. Magnification is ×400.

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