The appropriate standardized ileal digestible tryptophan to lysine ratio improves pig performance and regulates hormones and muscular amino acid transporters in late finishing gilts fed low-protein diets.

This study investigated the effects of various standardized ileal digestible (SID) Trp to Lys ratios on the performance and carcass characteristics of late finishing gilts receiving low-CP (9.6%) diets supplemented with crystalline AA. Ninety gilts (89.1 ± 5.1 kg) were used in a dose-response study conducted for 35 d. Crystalline Trp (0, 0.1, 0.2, 0.4, or 0.6 g/kg) was added to a corn-wheat bran basal diet providing SID Trp to Lys ratios of 0.12, 0.15, 0.18, 0.21, or 0.24. Each diet was fed to 6 pens of pigs with 3 gilts per pen. At the end of the experiment, 30 gilts (1 pig per pen) were slaughtered to evaluate carcass traits and meat quality (BW = 121 kg). Increasing the SID Trp to Lys ratio increased ADG (linear and quadratic effect, < 0.05) and also improved G:F (linear and quadratic effect, < 0.05). Serum urea nitrogen (SUN) decreased as the SID Trp to Lys ratio increased (linear and quadratic effects, < 0.05). A quadratic effect of L* light and marbling in the longissimus dorsi was observed as the dietary SID Trp to Lys ratio increased ( < 0.05). Increasing the SID Trp to Lys ratio increased the level of serum GH (quadratic effect, < 0.05) and also increased the level of serum IGF-1 (linear and quadratic effect, < 0.05). Increasing the SID Trp to Lys ratio increased the protein abundance of the muscular AA transporter of sodium-coupled neutral amino acid transporter 2 (SNAT2) in the longissimus dorsi muscle (linear and quadratic effect, < 0.05). The optimum SID Trp to Lys ratios to maximize ADG and G:F as well as to minimize SUN levels were 0.16, 0.17, and 0.16 using a linear-breakpoint model and 0.20, 0.20, and 0.20 using a quadratic model. Tryptophan could influence serum GH and IGF-1 secretion and protein abundance of the muscular AA transporter of SNAT2 in the longissimus dorsi muscle in late finishing gilts fed low-protein diets.

The essential oil of bergamot enhances the levels of amino acid neurotransmitters in the hippocampus of rat: implication of monoterpene hydrocarbons.

The effects of bergamot essential oil (BEO) on the release of amino acid neurotransmitters in rat hippocampus have been studied by in vivo microdialysis and by in vitro superfusion of isolated nerve terminals. Intraperitoneal administration of BEO (100microl/kg) significantly elevated the extracellular concentration of aspartate, glycine and taurine in a Ca(2+)-dependent manner. A dose-relation study generated a bell-shaped curve. When perfused into the hippocampus via the dialysis probe (20microl/20min), BEO produced a significant increase of extracellular aspartate, glycine, taurine as well as of GABA and glutamate. The augmentation of all amino acids was Ca(2+)-independent. Focally injected 1:1 diluted BEO preferentially caused extracellular increase of glutamate. Interestingly, this release appeared to be strictly Ca(2+)-dependent. BEO concentration-dependently enhanced the release of [(3)H]D-aspartate from superfused hippocampal synaptosomes. Similar results were obtained by monitoring the BEO-evoked release of endogenous glutamate. At relatively high concentrations, the BEO-induced [(3)H]d-aspartate release was almost entirely prevented by the glutamate transporter blocker dl-threo-beta-benzyloxyaspartic acid (DL-TBOA) and was Ca(2+)-independent. At relatively low concentrations the release of [(3)H]D-aspartate was only in part ( approximately 50%) DL-TBOA-sensitive and Ca(2+)-independent; the remaining portion of release was dependent on extracellular Ca(2+). Interestingly, the monoterpene hydrocarbon-free fraction of the essential oil appeared to be inactive while the bergapten-free fraction superimposed the releasing effect of BEO supporting the deduction that psoralens may not be implicated. To conclude, BEO contains into its volatile fraction still unidentified monoterpene hydrocarbons able to stimulate glutamate release by transporter reversal and/or by exocytosis, depending on the dose administered.

Nutritional benefits of enteral alanyl-glutamine supplementation on rat small intestinal damage induced by cyclophosphamide.

BACKGROUND: Glutamine is the principal fuel used by the small intestine. Although the parental administration of glutamine promotes intestinal mucosal growth, it is controversial whether enteral glutamine is effective against small intestinal damage caused by chemotherapy. To further evaluate the benefits of enteral supplementation, peptide and amino acid transporter functions must be considered. METHOD: Rats were given cyclophosphamide (CPM) intraperitoneally (300 mg/kg). Expression of the amino acid transporter, B0 and peptide transporter (PepT1) in the jejunal mucosa was initially examined by northern blot analysis. Rats received a bolus oral supplement of an alanine (1.22 g/kg/day) plus glutamine (2.0 g/kg/day) mixture, alanyl-glutamine (2.972 g/kg/day) or saline as a control, for 7 days after CPM administration. RESULTS: Levels of B0 mRNA remained unchanged at both 3 and 7 days after CPM administration. Conversely, PepT1 mRNA increased significantly after CPM administration, and reached 200% of the initial level 7 days later. In rats given alanyl-glutamine, the mucosal wet weight and protein content increased significantly with increasing villus height at 3 and 7 days, compared with the alanine plus glutamine mixture. The plasma glutamine concentration in the alanyl-glutamine group, but not the alanine plus glutamine mixture group, increased significantly compared with that in the saline group. CONCLUSION: Enteral supplementation with an alanyl-glutamine but not alanine plus glutamine mixture prevents intestinal damage, as demonstrated by increased peptide transport expression and an elevated plasma glutamine concentration after CPM administration.