抄録
We previously reported that levels of plasma corticosterone of rats in the alternatively changing ambient temperature in a lower range (repeated temperature changes between 4°C and 27°C, each lasting for 1h) were higher than those in the constant low ambient temperature (4°C) at 1, 2, 4 and 10 days after the exposure. It was also reported that levels of corticosterone in the alternatively changing ambient temperature in a higher range (repeated changes between 18°C and 34°C, each lasting for 1h) were higher than those in the constant high ambient temperature (34°C) at day one post-exposure. Frequently changing, but not constant, ambient temperatures may have induced a stronger stress. Furthermore, LPS-induced fever in a group with high level of plasma corticosterone was enhanced. Plasma leukocytes counts and intrinsic LPS concentrations with the alternatively changing ambient temperature in a lower range, constant low ambient temperature and constant 25°C for 2days were determined for the elucidation of the mechanism of enhanced LPS-induced fever. There was no difference between these three groups in either parameters. It was not caused either by increased leukocytes counts nor by increased intrinsic levels of plasma LPS. The aim of the present experiments was to ravel underlying mechanisms of the enhanced LPS-induced fever in animals exposed to stressful ambient temperatures. For this purpose, changes of plasma cytokines such as IL-1β,TNF-α and endogenous plasma endotoxin (LPS) during LPS-induced fevers were monitored in rats 24h and 12h after temperature exposures. [J Physiol Sci. 2007;57 Suppl:S182]
