During hibernation, certain mammals can undergo a physiological state analogous to reversible suspended animation, with severe hypothermia and a core body temperature (CBT) close to 0oC. In non-hibernators including the human, this degree of hypothermia is fatal. It is well established that cells under hypoxia survive longer in hypothermic conditions due to slowing of metabolism, a feature with many clinical applications. Due to the risk of organ failure, clinical application of hypothermia is limited to a CBT of 32-34oC. Even at this temperature, the beneficial effect of controlled hypothermia is significant. The laboratory mouse is a non-hibernator but under caloric restriction it can undergo torpor (hibernating-like) behavior with a CBT of 31oC or below. Primates such as Malagasy lemurs can undergo torpor, suggesting that the basic mechanism for such behavior may be preserved in humans. We have recently identified endogenous 5?-adenosine monophosphate (5?-AMP) as a mediator of torpor behavior in mice. Our studies revealed that torpor behavior is linked to the regulation of blood glucose by 5?-AMP, an important allosteric regulator of several rate-limiting enzymes involved in glucose homeostasis. Our finding raised the possibility that non-hibernators can also achieve a state of suspended animation observed only in hibernating mammals. Using the physiological variables, 5?- AMP, environmental temperature and glucose, we can induce, sustain and rescue mice in suspended animation. Shivering, a sign of thermo-regulatory defense is blocked by 5?-AMP, allowing rapid cooling of CBT to 17oC or below, causing the animal to enter suspended animation. Recovery from a suspended animation state of up to 10 hours is spontaneous but was enhanced by glucose. Our goal is to bring this technology into two areas. 1) To explore the physiological limits of suspended animation in non-hibernating mammals. 2) To extend findings from the laboratory mouse to other non-hibernating mammals along the evolutionary chain.

Agency
National Institute of Health (NIH)
Institute
Office of The Director, National Institutes of Health (OD)
Type
NIH Director’s Pioneer Award (NDPA) (DP1)
Project #
5DP1OD000895-04
Application #
7683829
Study Section
Special Emphasis Panel (ZGM1-NDPA-G (P2))
Program Officer
Jones, Warren
Project Start
2006-09-28
Project End
2011-07-31
Budget Start
2009-08-01
Budget End
2010-07-31
Support Year
4
Fiscal Year
2009
Total Cost
$742,500
Indirect Cost
Name
University of Texas Health Science Center Houston
Department
Biochemistry
Type
Schools of Medicine
DUNS #
800771594
City
Houston
State
TX
Country
United States
Zip Code
77225
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