Effects of dietary calcium on adipocyte lipid metabolism and body weight regulation in energy-restricted aP2-agouti transgenic mice.
We have demonstrated previously a regulatory role for intracellular Ca2+ ([Ca2+]i) in adipocyte lipogenesis and lipolysis and have recently reported that 1,25-(OH)2-D increases adipocyte [Ca2+]i, which causes increased lipogenesis and decreased lipolysis. We have now tested the hypothesis that suppressing 1,25-(OH)2-D by increasing dietary calcium will suppress adipocyte [Ca2+]i, thereby facilitating weight loss by stimulating lipolysis and inhibiting lipogenesis in calorically (Kcal)-restricted (70% of ad lib) aP2-agouti transgenic (aP2-a) mice. Mice (aP2-a) exhibiting a pattern of obesity gene expression similar to humans were fed a low-Ca (0.4%)/high-fat/high-sucrose diet for six weeks, resulting in a 27% and twofold increase in body weight and total fat pad mass, respectively, with a twofold increase in adipocyte [Ca2+]i pad lib or Kcal-restricted (70% of ad lib) on this diet either unsupplemented (basal) or with 25% or 50% of the protein replaced by non-fat dry milk (medium or high) dairy or supplemented with CaCO3 to 1.2% Ca for six weeks. Adipocyte [Ca2+]i was unaffected by Kcal restriction but was reduced markedly by all three high Ca diets (290 vs. 130 nM, p2+]i and thereby reduce energy storage and increase thermogenesis during Kcal restriction.
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The University of Tennessee, Knoxville, TN 37996-1900, USA.
Dirienzo
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Zemel
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D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000273:Adipose Tissue / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology*; D000818:Animals; D001833:Body Temperature Regulation; D001835:Body Weight / Q000235:genetics; D002117:Calcitriol / Q000494:pharmacology; D002136:Calcium, Dietary / Q000494:pharmacology*; D004038:Diet, Reducing; D004734:Energy Metabolism / Q000235:genetics; D007473:Ion Channels; D050356:Lipid Metabolism; D008066:Lipolysis; D026901:Membrane Transport Proteins; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D024101:Mitochondrial Proteins; D008954:Models, Biological; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D000071246:Uncoupling Protein 2
D002136:Calcium, Dietary; D007473:Ion Channels; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D000071246:Uncoupling Protein 2; D002117:Calcitriol