Administration of adenosine-5′-monophosphate (5′-AMP) can induce an artificial but endogenously reversible torpor-like state in mice. The dynamics of body temperature and the relation between body temperature and metabolic rate may indicate the (dis)similarity of this artificial torpor-like state to natural torpor in intact animals. We investigated these in C57BL/6J mice by (1) comparing cooling rates during 5′-AMP induced hypothermia to cooling rates during high workload induced torpor, and by (2) estimating the relative contributions of metabolic suppression and passive temperature (Q 10) effects in the 5′-AMP induced hypothermic state. We did the latter by back-extrapolating the relation between body temperature and metabolic rate in hypothermic conditions to the euthermic temperature level, using calculated Q 10-values. The data indicate that (1) cooling rate in 5′-AMP induced hypothermia is about 1.8 times faster than in natural torpor in workload conditions, and that (2) Q 10 effects can entirely explain the metabolic reduction of 5′-AMP induced hypothermia, indicating that active metabolic suppression may be lacking. Together, this suggests fundamental differences between 5′-AMP induced hypothermia and natural torpor, limiting the validity of the paradigm to the study of effects of hypothermic conditions and temperature related metabolic effects.
|Title of host publication||Living in a Seasonal World|
|Subtitle of host publication||Thermoregulatory and Metabolic Adaptations|
|Editors||W. Arnold, C. Bieber, E. Millesi, T. Ruf|
|Place of Publication||Berlin, Heidelberg|
|Number of pages||12|
|Publication status||Published - 2012|