Effects of fission neutrons on human thyroid tissues maintained in SCID mice.
Morphology and function (secretion of thyroid hormone) of human thyroid tissues from Graves' disease patients are well maintained in C57BL/6J-scid mice. Serum level of thyroid hormone was reduced by fission neutrons from the nuclear reactor UTR-KINKI, and changes in thyroid hormone by fission neutrons were bigger than those by low LET radiations, X-rays and (137)Cs gamma-rays, suggesting high relative biological effectiveness (RBE; 6.5) of fission neutrons. Microarray analyses revealed that about 3% of genes showed more than 4-fold change in gene expression in the unexposed thyroid tissues against surgically resected thyroid tissues from the same patient, probably due to the difficult oxygen and nutrient supply shortly after transplantation. Dose-dependent changes in gene expression against unexposed concurrent controls were observed with increasing doses of fission neutrons (0.2-0.6Gy) and (137)Cs gamma-rays (1.0-3.0Gy) and showed high RBE (4.2). Furthermore, there were some specific genes which showed more than 4-fold change in gene expression in all the thyroid tissues exposed to higher doses of radiation, especially neutrons (0.4 and 0.6Gy), but none at lower doses (0.2Gy of neutrons and 1.0 and 2.0Gy of gamma-rays). These genes related to degeneration, regeneration, apoptosis, and transcription, respond specifically and very sensitively to neutron injury in human thyroid tissues. This is the first experimental report that fission neutrons can induce some morphological and functional disorders in human tissues, showing high RBE against gamma-ray exposure. These results are useful to evaluate the risks of fission neutrons and cosmic rays to humans.
Adachi
Shigeki
S
Department of Radiation Biology and Medical Genetics, Osaka University, Suita, Osaka, Japan.
Ryo
Haruko
H
Hongyo
Tadashi
T
Nakajima
Hiroo
H
Tsuboi-Kikuya
Rie
R
Tokita
Yoriko
Y
Matsuzuka
Fumio
F
Hiramatsu
Keizo
K
Fujikawa
Kazuo
K
Itoh
Tetsuo
T
Nomura
Taisei
T
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000009:adverse effects; D015870:Gene Expression / Q000528:radiation effects; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D009502:Neutrons / Q000009:adverse effects*; D009680:Nuclear Fission; D012062:Relative Biological Effectiveness; D013961:Thyroid Gland / Q000528:radiation effects* / Q000637:transplantation; D013963:Thyroid Hormones / Q000097:blood / Q000528:radiation effects; D014183:Transplantation, Heterologous
D013963:Thyroid Hormones