title: Hormone production in pituitary adenomas following external irradiation: an experimental study in rats.
abstract: 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.
authors.affiliation: Oral and Maxillofacial Surgery, Eppendorf University Hospital, University of Hamburg, 20246 Hamburg, Germany.
authors.forename: R E
authors.initials: RE
authors.lastname: Friedrich
authors.forename: W
authors.initials: W
authors.lastname: Saeger
authors.forename: R
authors.initials: R
authors.lastname: Laas
authors.forename: S B
authors.initials: SB
authors.lastname: Friedrich
mesh_terms: 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
chemical_list: D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone