Hormone production in pituitary adenomas following external irradiation: an experimental study in rats.
BACKGROUND
The aim of this study was to investigate the hormone production in pituitary gland tumors following fractionated external irradiation in rats.


METHODS
Sixty female Wistar rats 3 to 4 month of age at the beginning of the experiments, were subjected to fractionated roentgen-rays exposure, 2 Grays (Gy) daily, either up to 20, 40 or 60 Gy. The animals were sacrificed either 6 month or 1 year after completion of the randomly assigned irradiation protocol.


RESULTS
We found 9 pituitary tumors in 60 irradiated rats (15%). All tumors proved to be adenomas. Immunohistochemical analysis of hormone production in remnants of the normal adenohypophysis revealed immunoreactivity for growth hormone (GH), adrenocorticotropic hormone (ACTH), prolactin (PRL), thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH). In adenomas, 4 cases were immunoreactive for TSH, 4 for GH, 2 for PRL, and 2 for FSH. The tumors were not reactive with anti-ACTH and anti-LH (luteinizing hormone).


CONCLUSIONS
We concluded that irradiation accelerates the development of pituitary gland adenomas. In our series these tumors were predominantly incidental findings at necropsies after pre-termed follow-up, with a variety of hormone producing tumor cells. However, 4 of 9 tumors in our study were not producing hormones.
Friedrich
R E
RE
Oral and Maxillofacial Surgery, Eppendorf University Hospital, University of Hamburg, 20246 Hamburg, Germany.
Saeger
W
W
Laas
R
R
Friedrich
S B
SB
D000818:Animals; D005260:Female; D013006:Growth Hormone / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D011388:Prolactin / Q000378:metabolism; D015175:Prolactinoma / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy; D051381:Rats; D017208:Rats, Wistar; D013972:Thyrotropin / Q000378:metabolism
D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone