Abstract
It has been reported that the core temperature (Tc) in rats increases due to loose restraint. In this study, various patterns of Tc change were observed under various restraint conditions. The relationships between the response pattern in Tc change and the restraint condition were studied. A radiotelemetry transmitter was implanted into the peritoneal cavities of adult male Wistar rats, and Tc and locomotor activity were continuously recorded using the telemetry system. The rats were reared in individual plastic cages under a 12h/12h light dark cycle (6:00 lights on), and the room temperature was kept at 24°C. Restraint for 60 min by a loosely fitting, small wire cage (9:00-10:00) was repeated for eight consecutive days. During the restraint, rectal temperature (Tre) was sometimes detected by the thermistor probes. Daily consumption of food and water was measured. Circadian rhythm of Tc was distinct, Tc was high at nighttime and low in the daytime. Due to restraint stress, various patterns of Tc change were recorded, namely an increase, a decrease, or a decrease followed by an increase. The patterns of Tc changed gradually in the course of the eight-day consecutive restraint experiment. After release from restraint, the Tc increased transiently. When Tre was recorded in addition to the telemetry recoding, the Tc increasing pattern was frequently observed. From these results, complex response patterns to restaurant stress may be depend on various restraint conditions. [Jpn J Physiol 55 Suppl:S227 (2005)]
