Adaptive response in embryogenesis: II. Retardation of postnatal development of prenatally irradiated mice

We previously reported that a priming dose of 0.3 Gy on gestation day 11 si gnificantly increased the rate of living fetuses and reduced the incidence of congenital malformations caused by exposure to 5 Gy X rays on gestation day 12 in ICR mice. In the present study, postnatal development of the live offspring was investigated using a set of developmental and behavioral par ameters. The offspring of the mice irradiated with 0.3 Gy generally showed a delay in the appearance of most of the physiological markers, impaired ac quisition of neonatal reflexes, and alteration of adult behavior. However, an increase in body weight in the females was observed 4 weeks postnatally. In the offspring primed with 0.3 Gy followed by a challenging dose of 5 Gy prenatally, a high postnatal mortality was found, and all the survivors ha d various radiation-induced detrimental effects. The results indicated that the priming dose was advantageous to survival itself but was disadvantageo us to the health of survivor. The results also suggested that studying the whole animal can show the extent of the effects of radiation, i.e. quality of life, in a way that cellular or molecular studies cannot. (C) 1999 by Ra diation Research Society.