Radiation-induced apoptosis in relation to acute impairment of rat salivary gland function.
OBJECTIVE
To find an answer to the question: Are the acute radiation effects on salivary gland function, as seen in earlier studies, causally related to radiation-induced apoptosis?


METHODS
Rat parotid and submandibular glands were X-irradiated with doses up to 25 Gy and morphological damage assayed up to 6 days after irradiation. Damage to the different cell types in the glands was assessed after H & E staining. Apoptotic appearance was judged by compacted chromatin and fragmentation of cells into lobulated masses.


RESULTS
In about 3% of the cells aberrant nuclei were observed after doses as low as 2 Gy and around 7.5 and 24 h after irradiation. About half of these aberrant nuclei had an apoptotic appearance. After a dose of about 5 Gy no dose-response for apoptotic cells was found, as evidenced by a plateau in the dose-effect curve. At 6 days after 2 Gy, no signs of radiation-induced apoptosis was apparent and for most cell types a value close to zero was observed.


CONCLUSIONS
Radiation studies on salivary function in the rat show the typical response with respect to dose (5-15 Gy) and time (1-3 days). This differs from reported findings with light microscopy. Therefore, the extent of apoptosis induced by radiation cannot explain the observed gland malfunction. Alternative mechanisms are proposed.
Department of Radiotherapy, University Hospital Groningen, The Netherlands.
G M
GM
Paardekooper
S
S
Cammelli
L J
LJ
Zeilstra
R P
RP
Coppes
A W
AW
Konings
D000681:Amylases / Q000378:metabolism / Q000528:radiation effects; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D002467:Cell Nucleus / Q000473:pathology / Q000528:radiation effects; D008297:Male; D010306:Parotid Gland / Q000201:enzymology / Q000473:pathology / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D013363:Submandibular Gland / Q000201:enzymology / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors; D014965:X-Rays
D000681:Amylases