The effect of low level prenatal X-irradiation on postnatal growth in the Wistar rat.
Forty-five pregnant Wistar strain rats were exposed to 0.0, 0.4, 0.6, or 0.8 Gy X-radiation on the 9th or 17th day of gestation to determine if prenatal X-irradiation would result in alterations in postnatal growth or growth rate. The mothers delivered their offspring, and the litters were reduced to a maximum of eight per litter on the second postnatal day. The 336 offspring were weighed weekly from day 3 until day 86, at which time they were killed, an autopsy was performed, and selected organs were removed and weighed. Postnatal growth rates did not differ significantly in irradiated offspring compared to sham irradiated animals. Irradiation on the 9th day, at any of the 3 dosage levels, did not result in significant differences in weekly weight. Weekly weight remained significantly lower due to irradiation on the 17th day of gestation. The gonadal weight ratio was significantly reduced in males irradiated on the 9th day. There were no other statistically significant changes in organ weight or organ/body weight ratios due to these levels of prenatal X-irradiation on the 9th or 17th day of pregnancy. These results indicate that low level prenatal X-irradiation, on the 17th day of rat gestation, causes prenatal growth retardation, evident at birth, which is not recuperable postnatally. Exposure to X-radiation at this time, however, does not affect the rate at which offspring grow during postnatal life. Offspring are smaller because they never fully recover from the original radiation-induced prenatal growth retardation.
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Department of Anatomy, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Brent
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D000818:Animals; D001835:Body Weight / Q000528:radiation effects*; D005260:Female; D005865:Gestational Age; D008297:Male; D009929:Organ Size / Q000528:radiation effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000528:radiation effects