title: The effects of branched-chain amino acid interactions on growth performance, blood metabolites, enzyme kinetics and transcriptomics in weaned pigs.
abstract: The impact of excess dietary leucine (Leu) was studied in two growth assays with pigs (8-25 kg). In each trial, forty-eight pigs were allotted to one of six dietary groups. The dietary Leu supply increased from treatment L100 to L200 (three increments). To guarantee that interactions between the branched-chain amino acids (BCAA) were not cushioned either surpluses of isoleucine (Ile, expt 1) or valine (Val; expt 2) were avoided. In the fifth treatment, the effects of a simultaneous excess of Leu and Val (expt 1), or of Leu and Ile (expt 2) were investigated. The sixth treatment was a positive control. An increase in dietary Leu decreased growth performance, and increased plasma Leu and serum alpha-keto-isocaproate levels in a linear, dose-dependent manner. Levels of plasma Ile and Val, and of serum alpha-keto-beta-methylvalerate and alpha-keto-isovalerate, indicated increased catabolism. Linear increases in the activity of basal branched-chain alpha-keto acid dehydrogenase in the liver confirmed these findings. No major alterations occurred in the mRNA of branched-chain amino acid catabolism genes. In liver tissue from expt 2, however, the mRNA levels of growth hormone receptor, insulin-like growth factor acid labile subunit and insulin-like growth factor 1 decreased significantly with increasing dietary Leu. In conclusion, excess dietary Leu increased the catabolism of BCAA mainly through posttranscriptional mechanisms. The impact of excess Leu on the growth hormone--insulin-like growth factor-1 axis requires further investigation.
authors.affiliation: Department für Tierwissenschaften, Lehrstuhl für Tierernährung, Technische Universität München, Hochfeldweg 6, Freising D-85350, Germany.
authors.forename: Markus Karl
authors.initials: MK
authors.lastname: Wiltafsky
authors.forename: Michael Walter
authors.initials: MW
authors.lastname: Pfaffl
authors.forename: Franz Xaver
authors.initials: FX
authors.lastname: Roth
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide) / Q000378:metabolism*; D000597:Amino Acids, Branched-Chain / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005260:Female; D020869:Gene Expression Profiling; D007532:Isoleucine / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D007651:Keto Acids / Q000097:blood*; D007930:Leucine / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*; D016014:Linear Models; D008099:Liver / Q000378:metabolism; D008660:Metabolism / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000235:genetics / Q000378:metabolism; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism; D013552:Swine / Q000254:growth & development* / Q000378:metabolism; D014633:Valine / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D014886:Weaning
chemical_list: D000597:Amino Acids, Branched-Chain; D007651:Keto Acids; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D013002:Somatomedins; D007532:Isoleucine; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D007930:Leucine; D014633:Valine