Fatty acid synthesis and generation of glycerol-3-phosphate in brown adipose tissue from rats fed a cafeteria diet.
In vivo fatty acid synthesis and the pathways of glycerol-3-phosphate (G3P) production were investigated in brown adipose tissue (BAT) from rats fed a cafeteria diet for 3 weeks. In spite of BAT activation, the diet promoted an increase in the carcass fatty acid content. Plasma insulin levels were markedly increased in cafeteria diet-fed rats. Two insulin-sensitive processes, in vivo fatty acid synthesis and in vivo glucose uptake (which was used to evaluate G3P generation via glycolysis) were increased in BAT from rats fed the cafeteria diet. Direct glycerol phosphorylation, evaluated by glycerokinase (GyK) activity and incorporation of [U-14C]glycerol into triacylglycerol (TAG)-glycerol, was also markedly increased in BAT from these rats. In contrast, the cafeteria diet induced a marked reduction of BAT glyceroneogenesis, evaluated by phosphoenolpyruvate carboxykinase-C activity and incorporation of [1-14C]pyruvate into TAG-glycerol. BAT denervation resulted in an approximately 50% reduction of GyK activity, but did not significantly affect BAT in vivo fatty acid synthesis, in vivo glucose uptake, or glyceroneogenesis. The data suggest that the supply of G3P for BAT TAG synthesis can be adjusted independently from the sympathetic nervous system and solely by reciprocal changes in the generation of G3P via glycolysis and via glyceroneogenesis, with no participation of direct phosphorylation of glycerol by GyK.
Chaves
Valéria E
VE
Department of Physiology, School of Medicine, University of Sao Paulo, 14049-900 Ribeirao Preto, Sao Paulo, Brazil.
Frasson
Danúbia
D
Martins-Santos
Maria E S
ME
Navegantes
Luiz C C
LC
Galban
Victor D
VD
Garófalo
Maria A R
MA
Kettelhut
Isis C
IC
Migliorini
Renato H
RH
D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D001823:Body Composition / Q000502:physiology; D003714:Denervation; D004032:Diet; D005227:Fatty Acids / Q000096:biosynthesis*; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D005994:Glycerophosphates / Q000096:biosynthesis*; D006153:Guanosine Diphosphate / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D008071:Lipoprotein Lipase / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014280:Triglycerides / Q000378:metabolism; D000071256:Uncoupling Protein 1
D005227:Fatty Acids; D005994:Glycerophosphates; D007328:Insulin; D007473:Ion Channels; D024101:Mitochondrial Proteins; D014280:Triglycerides; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate; D019289:Pyruvic Acid; D008071:Lipoprotein Lipase; D005947:Glucose; D005990:Glycerol; D009638:Norepinephrine