Adaptive response in embryogenesis: I. Dose and timing of radiation for reduction of prenatal death and congenital malformation during the late period of organogenesis.
An adaptive response was demonstrated during embryogenesis in mice. Whole-body irradiation at a dose of 0-50 cGy was given to condition pregnant ICR mice on day 9 to day 11 of gestation. Then their whole bodies were exposed to a challenging dose of 5 Gy on the next day. The numbers of living fetuses, prenatal deaths and living fetuses with external gross malformations were determined on day 19. A conditioning dose of 30 cGy on day 11 significantly increased the rate of living fetuses and reduced the incidence of congenital malformations induced by a 5-Gy dose on day 12. This indicates the existence of a critical dose and timing for administering a conditioning dose for radioadaptation during the late period of organogenesis in mice. The possible mechanisms involved are discussed.
Wang
B
B
Division of Radiobiology and Biodosimetry, National Institute of Radiological Sciences, Chiba, Japan.
Ohyama
H
H
Nose
T
T
Itsukaichi
H
H
Nakajima
T
T
Yukawa
O
O
Odaka
T
T
Tanaka
K
K
Kojima
E
E
Yamada
T
T
Hayata
I
I
D000016:Abnormalities, Radiation-Induced; D000220:Adaptation, Biological / Q000528:radiation effects*; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005314:Embryonic and Fetal Development / Q000528:radiation effects*; D005260:Female; D005313:Fetal Death / Q000209:etiology*; D018878:Limb Buds / Q000528:radiation effects; D017880:Limb Deformities, Congenital / Q000209:etiology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011247:Pregnancy; D013623:Tail / Q000002:abnormalities; D013997:Time Factors; D014916:Whole-Body Irradiation