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.
Paardekooper
G M
GM
Department of Radiotherapy, University Hospital Groningen, The Netherlands.
Cammelli
S
S
Zeilstra
L J
LJ
Coppes
R P
RP
Konings
A W
AW
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