Peripheral neural paths mediating avoidance of radiation in rats

¹ Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, Washington

The number of seconds per minute that male rats electively spent in a chamber X-irradiated at 32 r/min was measured in four groups: normal animals, animals which had received an intraperitoneal injection of 1 ml of 0.5% procaine, animals which had undergone bilateral splanchnicotomy, and sham-operated animals which had undergone all procedures preparatory to splanchnicotomy and which received 1 ml of distilled water intraperitoneally just before a test. Normal and sham-operated animals exhibited avoidance of radiation within 5 min of exposure, whereas splanchnicotomized or procainized rats showed no avoidance during the first 20 min of a 40-min test. It is suggested that an early component of radiation avoidance is mediated by splanchnic impulses elicited by the breakdown of the mucosa of the duodenum, small intestine, and, possibly, the stomach; and that breakdown of more resistant portions of the gastrointestinal mucosa (in the mouth, esophagus, and rectum) contributes to a late component.