Short-term hypothermia activates hepatic mitochondrial sn-glycerol-3-phosphate dehydrogenase and thermogenic systems

The contribution of the sn-glycerol 3-phosphate (G-3-P) shuttle in the cont rol of energy metabolism is well established. It is also known that its act ivity may be modulated by hormones involved in thermogenesis, such as thyro id hormones or dehydroepiandrosterone and its metabolites, that act by indu cing de novo synthesis of mitochondrial G-3-P dehydrogenase (mGPDH). Howeve r, little is: known as to the factors that may influence the activity witho ut enzyme induction. In the present study we investigated the possible role of the G-3-P shuttle in the thermogenic response to different hypothermic stresses. It was found that a decrease of body temperature causes the liver rapidly to enhance mGPDH activity and G-3-P-dependent respiration. The enh ancement, which does not result from de novo synthesis of enzymes, has the potential of increasing heat production both by decreased ATP synthesis dur ing the oxidation of G-3-P and by activation of the glycolytic pathway. (C) 2000 Academic Press.