Increased radiosensitivity of cerebral capillaries in neonatal Gunn rats as compared to Sprague-Dawley rats.
The extent of petechial haemorrhages of the cerebral cortex examined between 14 hours and 4 days after X-irradiation to the head was compared in Sprague-Dawley and homozygous Gunn rats with congenital hyperbilirubinaemia. Animals 1 to 2 days old received single doses of either 250, 500 or 750 rad. By means of a special scoring scale the degree of the damage to the microvasculature was semi-quantitatively estimated. In both strains a significant difference in effect was obtained between 250 and 500 rad, but not between 500 and 750 rad. The shape of the dose-effect curve in Gunn rats was similar to that of Sprague-Dawley rats, but displaced upwards. In Gunn rats the effect of 250 rad was greater than that of 750 rad in Sprague-Dawley rats. Possible radiosensitizing mechanisms are discussed with reference to the literature and our results.
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000098:blood supply*; D002196:Capillaries / Q000528:radiation effects; D002543:Cerebral Hemorrhage / Q000209:etiology; D004307:Dose-Response Relationship, Radiation; D006933:Hyperbilirubinemia, Hereditary / Q000150:complications*; D011833:Radiation Injuries, Experimental / Q000150:complications*; D051381:Rats; D014965:X-Rays