The British Journal of Radiology, Vol 73, Issue 865 51-57, Copyright © 2000 by British Institute of Radiology
Disappearance of stress-induced hyperthermia following a low dose of X-irradiation: involvement of the vomeronasal system in the modulation of the radiation-induced effects
Y Miyachi
Department of Physiology, Toho University School of Medicine, Tokyo, Japan.
When the rectal temperatures of group-housed mice are measured
sequentially, the temperature of the last mouse to be measured is higher
than that of the first mouse. The hyperthermia effect observed in the last
animal to be measured forms the basis of an experimental paradigm for
studying the neurobiology of anticipatory anxiety. Stress-induced
hyperthermia (SIH) was calculated as the difference (delta T) between the
basal temperature (the averages of the first three mice) and the final
temperature (the averages of the last three mice) when the temperatures of
the 15 mice were measured sequentially, with a 2 min interval between each
temperature measurement. The hyperthermia observed in the last animals
measured was abolished by prior treatment with X-irradiation at the
relatively low dose of 5-15 cGy. Prevention of the SIH response could be
found when the irradiation was confined to the head region only, suggesting
the importance of the brain in the radiation-induced effect. Relatively
higher doses of 25 or 35 cGy failed to reduce the hyperthermia stress
effect. Furthermore, the effect of X-irradiation was not observed following
olfactory bulbectomy or resection of the vomeronasal tract. These results
indicate that the disappearance of SIH response may only be found following
irradiation at low dose levels. Furthermore, the results implicate the
olfactory system in the radiation-induced anti-stress effect.
