Changes of body temperature and plasma corticosterone level in rats during psychological stress induced by the communication box

Background: We have reported that only psychological stress, but not physical stress, induces a significant elevation of body temperature following repeated exposures, however, we did not evaluate the effects of psychological stress in an acute case. In this study, we evaluated hormonal and physiological changes caused by an acute exposure to psychological stress in rats, compared to physical stress. Material and methods: Adult male Wistar rats, weighing 300-400 g, were exposed to foot shock or non-foot shock stress induced by the communication box for 1 h. The rats in the foot shock group received the electrical shock directly, and the rats in the non-foot shock group could escape from the electrical shock, but received various emotional stimuli from other foot-shocked rats in the communication box. Before, during and after the exposure to each stress, we measured body temperature and motor activity by means of the telemetry system, and also measured plasma corticosterone level by radioimmunoassay. Results: Non-foot shocked rats showed a significant elevation of body temperature (from 37.18±0.13°C at baseline to the peak, 38.71±0.10°C), in association with a slight but significant increase in motor activity, and a temporal elevation of plasma corticosterone (from 22.1±1.6 μg/dl at baseline to 29.5±2.7 μg/dl). These changes were at a lower magnitude compared to foot shocked rats. Conclusion: It is concluded that psychological stress, generated by the communication box, could have lower influences as an acute stress than physical stress.