Lipogenesis in rat tissues following carbohydrate refeeding: spleen lipogenesis is modulated by insulin.

Intraperitoneal administration of [1,2-14C]-acetate to Wistar rats was used to assess tissue lipogenic rates after estimating the incorporation of the label into the tissular lipid fractions. Refeeding the animals with glucose (after an overnight fast) induced an increase in white adipose tissue (4.5 fold), liver (4.1 fold), small intestine (1.9 fold), carcass (2.9 fold) and spleen (3.7 fold) lipogenesis (expressed as the radioactivity present in the lipid fraction corrected by the plasma circulating radioactivity). No changes were found following refeeding in either brain or brown adipose tissue. Administration of mannoheptulose (an inhibitor of insulin secretion) to refed rats completely abolished the increased lipogenesis in white adipose tissue, liver, carcass, spleen and small intestine, thus suggesting that insulin secretion is involved in this phenomenon. This is the first report showing that spleen lipogenesis may be modulated by refeeding via insulin secretion and suggests an important role of this organ on the in vivo lipogenic response of the organism after carbohydrate refeeding.