Showing papers by "Monica Bellei published in 1993"
TL;DR: Results provide evidence which supports the proposed hypothesis that DHEA enhances thermogenesis and decreases metabolic efficiency via trans-hydrogenation of cytosolic NADPH into mitochondrial FADH2 with a consequent loss of energy as heat.
Abstract: Dehydroepiandrosterone (DHEA) treatment of rats decreases gain of body weight without affecting food intake; simultaneously, the activities of liver malic enzyme and cytosolic glycerol-3-P dehydrogenase are increased. In the present study experiments were conducted to test the possibility that DHEA enhances thermogenesis and decreases metabolic efficiency via trans-hydrogenation of cytosolic NADPH into mitochondrial FADH2 with a consequent loss of energy as heat. The following results provide evidence which supports the proposed hypothesis: (a) the activities of cytosolic enzymes involved in NADPH production (malic enzyme, cytosolic isocitrate dehydrogenase, and aconitase) are increased after DHEA treatment; (b) cytosolic glycerol-3-P dehydrogenase may use both NAD+ and NADP+ as coenzymes; (c) activities of both cytosolic and mitochondrial forms of glycerol-3-P dehydrogenase are increased by DHEA treatment; (d) cytosol obtained from DHEA-treated rats synthesizes more glycerol-3-P during incubation with fructose-1,6-P2 (used as source of dihydroxyacetone phosphate) and NADP+; the addition of citratein vitro further increases this difference; (e) mitochondria prepared from DHEA-treated rats more rapidly consume glycerol-3-P added exogenously or formed endogenously in the cytosol in the presence of fructose-1,6-P2 and NADP+.
35 citations
TL;DR: An attempt to identify the cause of decrease of gain in body weight during dehydroepiandrosterone (DHEA) treatment was made comparing the effects of hormone treatment on chickens and rats.
Abstract: 1. 1. An attempt to identify the cause of decrease of gain in body weight during dehydroepiandrosterone (DHEA) treatment was made comparing the effects of hormone treatment on chickens and rats. 2. 2. Chickens treated with DHEA for 7–10 days do not change their weight gain with respect to controls although their mitochondrial respiration and peroxisomal catalase (index of peroxisomal mass) were increased. 3. 3. Liver cytosolic malic enzyme and sn -glycerol-3-phosphate dehydrogenase were depressed in chickens treated with DHEA in comparison with activities in untreated controls. DHEA treatment did not increase the activity of mitochondrial sn -glycerol-3-phosphate dehydrogenase. 4. 4. In contrast to rat liver cytosolic sn -glycerol-3-phosphate dehydrogenase this enzyme in chicken liver was inactive with NADPH.
5 citations