Gluconeogenesis in brain and liver during daily torpor in deer mice (Peromyscus maniculatus)

Some of the most critical changes accompanying daily torpor are those gover ning energy supply and demand. The purpose of this study was to compare glu coneogenic and glycolytic enzyme maximal activities in brain and liver duri ng the daily torpor cycle in deer mice (Peromyscus maniculatus). Liver gluc oncogenic and glycolytic enzyme maximal activities decreased significantly during torpor, coinciding with previous studies demonstrating reductions in liver metabolism. The five-fold increase in liver gluconeogenic enzyme act ivities during arousal may allow for glucose synthesis for immediate use by glucose-reliant tissues. Limited reductions in brain glycolytic enzyme act ivities during daily torpor indicate that the potential for carbohydrate me tabolism in brain remains high in dormancy. Brain gluconeogenic enzymes had significantly higher activities during torpor and after arousal us compare d to pre-torpor values. These findings suggest that an increase in brain gl uconcogenic capacity is an important mechanism for maintaining carbohydrate metabolic function during daily torpor in deer mice.