Evidences of basal lactate production in the main white adipose tissue sites of rats. Effects of sex and a cafeteria diet.
Female and male adult Wistar rats were fed standard chow or a simplified cafeteria diet for one month. Then, the rats were killed and the white adipose tissue (WAT) in four sites: perigonadal, retroperitoneal, mesenteric and subcutaneous (inguinal) were sampled and frozen. The complete WAT weight in each site was measured. Gene expression analysis of key lipid and glucose metabolism enzymes were analyzed, as well as tissue and plasma lactate and the activity of lactate dehydrogenase. Lactate gradients between WAT and plasma were estimated. The influence of sex and diet (and indirectly WAT mass) on lactate levels and their relationships with lactate dehydrogenase activity and gene expressions were also measured. A main conclusion is the high production of lactate by WAT, practically irrespective of site, diet or sex. Lactate production is a direct correlate of lactate dehydrogenase activity in the tissue. Furthermore, lactate dehydrogenase activity is again directly correlated with the expression of the genes Ldha and Ldhb for this enzyme. In sum, the ability to produce lactate by WAT is not directly dependent of WAT metabolic state. We postulate that, in WAT, a main function of the lactate dehydrogenase path may be that of converting excess available glucose to 3C fragments, as a way to limit tissue self-utilization as substrate, to help control glycaemia and/or providing short chain substrates for use as energy source elsewhere. More information must be gathered before a conclusive role of WAT in the control of glycaemia, and the full existence of a renewed glucose-lactate-fatty acid cycle is definitely established.
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain.
Sofía
S
Arriarán
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain.
Silvia
S
Agnelli
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain; CIBER Obesity and Nutrition, Barcelona, Spain.
David
D
Sabater
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain; Institute of Biomedicine of the University of Barcelona, Barcelona, Spain; CIBER Obesity and Nutrition, Barcelona, Spain.
Xavier
X
Remesar
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain; Institute of Biomedicine of the University of Barcelona, Barcelona, Spain; CIBER Obesity and Nutrition, Barcelona, Spain.
José Antonio
JA
Fernández-López
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, Barcelona, Spain; Institute of Biomedicine of the University of Barcelona, Barcelona, Spain; CIBER Obesity and Nutrition, Barcelona, Spain.
Marià
M
Alemany
D052436:Adipose Tissue, White / Q000378:metabolism*; D000818:Animals; D005260:Female; D007773:Lactates / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012737:Sex Factors
D007773:Lactates