Secretion of saliva in X-irradiated rat submandibular glands.
The mechanism of radiation-induced dysfunction in rat submandibular glands was investigated at the cellular level. After X irradiation (single dose, 15 Gy), a vacuolation in the acinar cells or an enlargement of the acinar lumen was observed as a typical morphological change for 2 weeks. As observed using a video-enhanced contrast differential interference contrast (VEC-DIC) microscope, exocytosis and shrinkage of the acinar cells induced by application of pilocarpine (100 microM) were markedly suppressed for 5 days and then recovered to 80% of the control levels. Using an immunohistochemical method, no significant change was observed in amylase distribution, but a marked loss of aquaporin 5 was found in the acinar cells after the irradiation. The extent and time course of pilocarpine-induced mobilization of intracellular Ca(2+) did not change after the irradiation. We conclude that radiation-induced dysfunction in the salivary glands is due to an impairment of exocytosis and a reduction of water secretion. The loss of aquaporin 5 and possibly other membrane-fusion proteins in acinar cells may be the major mechanism underlying such a dysfunction.
Takagi
Koji
K
Department of Dentistry and Oral and Maxillofacial Surgery, Hamamatsu University School of Medicine, Hamamatsu, 431-3192 Japan.
Yamaguchi
Kazue
K
Sakurai
Takashi
T
Asari
Tetsuya
T
Hashimoto
Kenji
K
Terakawa
Susumu
S
D000681:Amylases / Q000378:metabolism; D000818:Animals; D051402:Aquaporin 5; D020346:Aquaporins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement; D007150:Immunohistochemistry; D008297:Male; D008565:Membrane Proteins; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D018715:Microscopy, Video; D010862:Pilocarpine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012463:Saliva / Q000378:metabolism* / Q000528:radiation effects*; D012469:Salivary Glands / Q000378:metabolism; D013363:Submandibular Gland / Q000378:metabolism* / Q000528:radiation effects*; D013997:Time Factors; D014965:X-Rays
C496040:Aqp5 protein, rat; D051402:Aquaporin 5; D020346:Aquaporins; D008565:Membrane Proteins; D010862:Pilocarpine; D000681:Amylases; D002118:Calcium