Effects of dietary l-lysine intake on the intestinal mucosa and expression of CAT genes in weaned piglets

Abstract

The objective of this study was to evaluate effects of dietary L-lysine on the intestinal mucosa and expression of cationic amino acid transporters (CAT) in weaned piglets. Twenty-eight piglets weaned at 21 days of age (Duroc × Landrace × Yorkshire; 6.51 ± 0.65 kg body weight) were assigned randomly into one of the four groups: Zein + LYS (zein-based diet + 1.35 % supplemental lysine), Zein - LYS (zein-based diet), NF (nitrogen-free diet), and CON (basal diet). The experiment lasted for 3 weeks, during which food intake and body weight were recorded. At the end of the trial, blood was collected from the jugular vein of all pigs, followed by their euthanasia. Dietary supplementation with lysine enhanced villus height and crypt depth in the jejunum (P < 0.05). Jejunal mRNA levels for the b(0,+)-AT, y(+)LAT1 and CAT1 genes were greater (P < 0.05) in the Zein + LYS group than in the control, and the opposite was observed for CAT1. Dietary content of lysine differentially affected intestinal CAT expression to modulate absorption of lysine and other basic amino acids. Thus, transport of these nutrients is a key regulatory step in utilization of dietary protein by growing pigs and lysine in the diet influences the expression of amino acid transporters in the small intestine.

Effects of reducing dietary protein on the expression of nutrition sensing genes (amino acid transporters) in weaned piglets

“…The present results indicate that the expression of ASCT2, EAAC1, B 0+ AT, and ATB 0 mRNA in the jejunum was influenced by dietary CP levels. Our results regarding the expression of y + LAT1 mRNA were similar to those of He et al (2013). Under conditions of nutritional stress, the expression of some AA transporters (y + LAT1) may be increased to maintain normal growth of animals under adverse conditions (He et al, 2013).…”

“…Our results regarding the expression of y + LAT1 mRNA were similar to those of He et al (2013). Under conditions of nutritional stress, the expression of some AA transporters (y + LAT1) may be increased to maintain normal growth of animals under adverse conditions (He et al, 2013). Skalli et al (2014) suggest that dietary protein levels regulate the expression of AA transporter genes by a complex regulatory system, which may also affect the energy balance and endocrine system.…”

“…Overall, the use of low-CP (14%) AA-supplemented diets in piglets may decrease the transport capacity of AA in the small intestine. However, the absorption and transport of AA is a complex physiological process that is influenced by many factors (Wang et al, 2009;He et al, 2013; Zhang et al, 2013;Chen et al, 2014), including the dietary CP level and the AA balance. Thus, the transport of these nutrients is a key regulatory step in the use of dietary protein by weaned piglets.…”

“…The following protocol was used: (1) . Target mRNA and β-actin mRNA were amplified with comparable efficiencies (Wang et al, 2009;He et al, 2013). Negative controls, in which cDNA was replaced by water, were also tested (Liu et al, 2012).…”

Dietary L-Lysine Prevents Arterial Calcification in Adenine-Induced Uremic Rats

“…Because the adenine rats ate a lower amount of the diet (Table 1), a balance between intestinal absorption and the catabolism of L-Lys seems to determine plasma Lys levels. Second, an induction of amino acid transporters, such as b 0,+ -AT and y + LAT-1 systems, in the intestine might increase intestinal absorption of Arg and His in 45 Absorbed L-Arg and L-His can be converted to L-Pro, L-Gln, and/or L-Ala through the pathway shown in Supplemental Figure 4. The presence of elevated plasma ornithine, a metabolite of L-Arg, in group Lys supports the idea that the metabolic flow from L-Arg to L-Pro, L-Gln, and/or L-Ala was very high in group Lys (Supplemental Table 2).…”