title: The effect of cervical X-irradiation on activity index of thyrocytes and plasma TSH: a pre-clinical model for radiation-induced thyroid damage.
abstract: Because radiotherapy in the head and neck region is necessary in the treatment of childhood cancer, possibilities to prevent damage to the thyroid gland must be explored. We developed a model in which radiation-induced effects can be investigated in a way that these effects can be quantified, using thyroid dysmorphology and plasma TSH. Thirty-five Wistar rats, 5 weeks old, were X-irradiated on the cervical region, with a single dose varying from 0 to 20 Gy. After 6 weeks, TSH, T4 and T3 were determined, and thyroid glands were processed for histological examination by two independent pathologists. A histological classification scale was developed, using follicular size, colloid density and cell height of thyrocytes to measure hyperplasia and hypertrophy. By the sum of these scores, a cell-activity index was calculated, which was related to plasma TSH concentration. Numbers of PAS-positive droplets and epithelial desquamation were also counted. Inter-observer reliability was assessed. Good to very good reliability was found for scores of follicular size, colloid density and cell height. Significant increase of cell-activity index was found after 10, 15 and 20 Gy. The plasma TSH concentration was positively correlated to the cell-activity index, increasing with radiation-doses up to 15 Gy. The number of desquamated cells was significantly increased after radiation doses >10 Gy, with moderate reliability. In conclusion, this model using cell-activity index of thyrocytes together with plasma thyrotropin concentrations and desquamation of cells can be used for interpretation and future (pre-clinical) studies of prevention of radiation-induced thyroid damage.
authors.affiliation: Division of Pediatric Endocrinology, Department of Pediatrics, Emma Children's Hospital, Amsterdam, The Netherlands. h.m.vansanten@amc.uva.nl
authors.forename: H M
authors.initials: HM
authors.lastname: van Santen
authors.forename: J E
authors.initials: JE
authors.lastname: Van Dijk
authors.forename: H
authors.initials: H
authors.lastname: Rodermond
authors.forename: F
authors.initials: F
authors.lastname: Vansenne
authors.forename: N
authors.initials: N
authors.lastname: Meertens
authors.forename: J
authors.initials: J
authors.lastname: Haveman
authors.forename: E
authors.initials: E
authors.lastname: Endert
authors.forename: J J M
authors.initials: JJ
authors.lastname: De Vijlder
authors.forename: T
authors.initials: T
authors.lastname: Vulsma
mesh_terms: D000818:Animals; D002572:Cervical Plexus / Q000528:radiation effects*; D008297:Male; D011833:Radiation Injuries, Experimental / Q000097:blood / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000166:cytology* / Q000473:pathology / Q000528:radiation effects*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine