Effect of excess levels of lysine and leucine in wheat‐based, amino acid‐fortified diets on the mRNA expression of two selected cationic amino acid transporters in pigs

Abstract

An experiment was conducted to evaluate the effect of excess levels of Leu and Lys on the expression of b(0,+) and CAT-1 mRNA in jejunum, liver and the muscles Longissimus dorsi (LDM) and Semitendinosus (STM). Twenty pigs with an average initial BW of 16.4 ± 1.7 kg were used in a Randomized Complete Block. Dietary treatments (T) were as follows: T1, basal diet; T2, basal plus 3.5 g l-Lys/kg diet; T3, basal plus 1.5 g l-Leu/kg diet; T4, basal plus 3.5 g l-Lys plus 1.5 g l-Leu/kg diet. Diets in T1 and T3 met 100% the requirement of Lys for pigs within the 10 to 20 kg body weight range; diets in T2 and T4 contained 35% excess of Lys. Also, diets in T1 and T2 supplied 104%, whereas diets in T3 and T4 supplied 116% the requirement of Leu. The expression of b(0,+) in jejunum was reduced (p = 0.002) because of the supplementation of l-Leu, but l-Lys supplementation had no effect (p = 0.738). In contrast, the expression of b(0,+) in STM (p = 0.012) and liver (p = 0.095) was reduced by the high level of Lys, but Leu had no effect (p > 0.100). CAT-1 expression in STM increased by high Lys (p = 0.023) and Leu (p = 0.007) levels. In liver, the expression of CAT-1 substantially increased (p = 0.001) because of Lys. In conclusion, excess levels of dietary Lys and Leu affect the expression of cationic amino acid transporters, and this effect varies depending on the studied tissue.

Effect of L‐lysine on expression of selected genes, serum concentration of amino acids, muscle growth and performance of growing pigs

“…Similar results were published by Morales et al. () in pigs fed a wheat diet supplemented with moderate excess (35%) of free Lys. Based on the higher serum Lys in pigs fed the ADE, as compared to the DEF diet, a higher flow of Lys from the small intestine to liver is expected.…”

“…Although the expression of CAT‐1 in jejunum was only approximately 1% of that of b 0,+ AT, which is in agreement with Morales et al. (), the differential expression of CAT‐1 in jejunum suggests a cellular mechanism in pigs fed the Lys DEF diet to absorb all the available cationic AA. Surprisingly, the expression of CAT‐1 in jejunum was highly correlated with that of b 0,+ AT in liver ( r = 0.95; p < 0.001), but the biological significance of this association is not clear because of the low expression in their respective tissues.…”

Expression of genes coding for selected amino acid transporters in small intestine, liver, and skeletal muscle of pigs fed excess branched-chain amino acids

“…Thus, the efflux of cationic AA from the enterocyte through CAT1 appears to be related to influx of these AA via b 0 , + AT. The lack of an effect of BCAA on CAT1 expression in the jejunum confirms the results of a previous study (Morales et al, 2013) and indicates that CAT1 is not directly related to the neutral AA.…”

“…The transporter b 0 , + AT exchanges Lys for neutral AA, particularly Leu Majumder et al, 2009) AT that is coupled with the efflux of Leu (Pineda et al, 2004). We recently observed reduced expression of b 0 , + AT in growing pigs (García-Villalobos et al, 2012;Morales et al, 2013) fed excess Leu diets, and surplus Ile failed to correct the reduction (Cervantes-Ramírez et al, 2013). However, there is limited information regarding the effect of adding surplus Ile and Val to diets with excess Leu on the abundance of transport systems for BCAA and cationic AA (Lys) in growing pigs.…”

<small>L</small>-Lysine Attenuates Hepatic Steatosis in Senescence-Accelerated Mouse Prone 8 Mice

“…It was reported that the mRNA expression level of cationic amino acid transporter (CAT-1) in the liver is increased by intake of Lys in pigs (39), and three basic amino acids (Lys, Arg, and His) are commonly transported via CAT-1 (40). Additionally, His is reported to suppress lipogenesis-related genes in the mouse liver (41).…”