Diurnal variation of heart rate, locomotor activity, and body temperature in interleukin-1α/β doubly deficient mice

Abstract

This study was investigated the roles of interleukin-1 (IL-1) on diurnal rhythms of heart rate (HR), locomotor activity (LA), and body temperature (BT). For this purpose, HR, LA, and BT were recorded from conscious and unrestrained IL-1α/β doubly deficient (KO) and normal C57BL/6J mice using a telemetry system. These parameters were continuously recorded from just after to 2 weeks after transmitter implantation, because we thought that the surgical stress-induced IL-1 might affect the biobehavioral activities of the animals. At 1 day after implantation, HR and LA in IL-1α/β KO mice were higher than those in C57BL/6J mice. While BT in IL-1α/β KO mice was lower than that in C57BL/6J mice. Moreover, diurnal rhythmicity in these parameters after implantation in IL-1α/β KO mice appeared earlier than in C57BL/6J mice. At 2 weeks after implantation, there were no significant differences in the light- and dark-phase values of each parameter between IL-1α/β KO and C57BL/6J mice, however, IL-1α/β KO mice showed clear ultradian rhythmicity. It is thought that a phenotypical difference in biobehavioral activities between IL-1α/β KO and C57BL/6J mice may reflect IL-1 induced febrile and behavioral responses. These results suggest that IL-1 may play important physiological and pathophysiological roles on biobehavioral activities.