Consumption of resistant starch decreases lipogenesis in adipose tissues but not in muscular tissues of growing pigs

The aim of the present study was to evaluate the effect of two different sources of starch on plasma glucose, acetate and insulin responses and peripheral lipogenesis in adipose and skeletal muscle tissues. Eighteen male growing pigs were fed a diet containing 250 g native corn starch/kg (CS; 26% amylose, 74% amylopectin) or 250 g raw potato starch/kg (RPS; 20% amylose, 80% amylopectin) as examples of digestible and resistant starch (type II), respectively. After 38 days on the experimental diets, twelve pigs (6 per treatment, Experiment 1) were killed and samples of adipose and muscular tissues were analysed for intramuscular lipid content and lipogenic enzyme activity. Lipogenic enzyme activities were significantly higher for CS than RPS in adipose tissues but not in muscular tissues. No differences were detected on the lipid content of the muscles tested. The six remaining pigs (3 per treatment, Experiment 2) were fitted with catheters in the saphenous vein and femoral artery after 28 days on the experimental diets. After feeding restoration to a level of 1.1 kg/day, they received a primed constant infusion of 1-¹³C acetate for a period of 90 min, starting 5 h after feeding the meal ingestion, and a primed constant infusion of 6,6-D₂ glucose for 7 h, starting 1 h before the following meal ingestion. No differences were observed between diets on peripheral acetate entry rate. Glucose concentration, the rate of peripheral glucose appearance and insulin concentration were quantitatively higher after the meal for CS than for RPS diet. This shows the importance of type of dietary starch on lipogenesis as a result of changes in glycemia and insulinemia in adipose but not in muscular tissues of growing pigs.