1. 1|According to the 'hibernation induction trigger' (HIT) theory, a chemical exists in the blood of hibernating or winter-sleeping animals that can induce hibernation and even affect body temperature and the activity of non-hibernators. However, results of studies on this subject are rather ambiguous. 2. 2|In this study, plasma from winter-sleeping European brown bear (Ursus arctos arctos) was injected into Djungarian hamsters (Phodopus sungorus) and laboratory rats (Sprague-Dawley) to test its ability to induce changes in the body temperature and activity of the recipients. 3. 3|The measurements were performed using radio telemetry. 4. 4|In all trials, the plasma had no effects on the body temperature or activity of the recipients. 5. 5|Our results suggest that there is no universal HIT-substance in the plasma of the European brown bear. © 1994.
Karjalainen, M., Hohtola, E., & Hissa, R. (1994). No metabolic suppression in the djungarian hamster or rat by injections of plasma from the winter-sleeping brown bear. Journal of Thermal Biology, 19(5), 321–325. https://doi.org/10.1016/0306-4565(94)90068-X