Liver RNA biosynthesis in adrenalectomized rats: effect of whole-body X-irradiation.

Exposure of rats to a single whole-body dose of X-rays led to an enhanced rate of RNA synthesis in the liver during 4 to 18 hours post-irradiation. This increase in RNA synthesis could not be obliterated by protecting the liver during irradiation. On the other hand, if adrenals were surgically removed prior to whole-body radiation exposure, no elevation either in liver RNA synthesis in vivo or liver chromatin template activity in vitro was apparent. Protection of only the head during irradiation could also prevent the stimulation in liver RNA synthesis in vivo. These results are suggestive of the involvement of neuro-endocrine reactions along the hypothalamus-pituitary-adrenal axes to be the underlying factors in whole-body radiation-evoked activation of the transcription machinery in the liver.