The current views about mammalian hibernation were developed using traditional models such as the ground squirrel. In these models, hibernators periodically rewarm to active levels between bouts of depressed metabolism. In this research, a unique model of hibernation will be used. Common tenrecs (Tenrec ecaudatus) originate from Madagascar and in contrast to all other known hibernators, do not periodically arouse from hibernation. Moreover, these mammals have a very variable active body temperature, which allows for direct comparison between active and hibernating tenrecs at the same body temperatures. This research will determine the extent and duration of metabolic savings associated with hibernation. In addition, studies will determine how kidney function, protein synthesis, and protein degradation are affected by body temperature and hibernation status in tenrecs. It is anticipated that this research will not only reveal the underlying mechanisms for this novel form of hibernation, but provide insight into the evolution of hibernation. Students will receive research training throughout the course of this project and outreach efforts will include development of a television program on hibernation.
Tenrecs may be the closest extant representative to the early placental mammal ancestor. Surprisingly little is known of the physiology of tenrecs and even less is known about their unusual mode of hibernation. The common tenrec, Tenrec ecaudatus, normally experiences wide fluctuations in body temperature and we found these animals experience a novel form of hibernation wherein animals are consistently lethargic throughout the Austral winter. Even when handled or held at warm temperatures, tenrecs do not arouse to the extent seen in other small hibernators such as ground squirrels. The investigators will combine respirometry measurements with telemetric measurements of heart rate, blood pressure, and tissue oxygenation, to understand the energetics of metabolic suppression. Since vital homeostatic processes such as renal function and protein metabolism are essentially restricted to the interbout arousal in rodents like ground squirrels, the lack of an interbout arousal in the tenrecs begs the question of the status of these processes. They will determine how tenrec glomerular filtration and renal blood flow are affected by body temperature and hibernation. In addition, the status of transcription, translation, and protein degradation during hibernation in tenrecs will be monitored. These data will serve as an important mechanistic foundation for understanding hibernation in tenrecs and, importantly, will serve as a platform for understanding the function and perhaps evolution of the interbout arousal- a feature common to all other known small mammal hibernators.
