Dietary supplementation with cholesterol and docosahexaenoic acid affects concentrations of amino acids in tissues of young pigs

Abstract

Cholesterol and docosahexaenoic acid (DHA) are important nutrients for neural development of infants. However, little is known about the effect of cholesterol or DHA on concentrations of amino acids (AA) in neonatal tissues. This study was conducted with the piglet (an established model for studying human infant nutrition) to test the hypothesis that dietary supplementation with the lipids may modulate AA availability in tissues. Sixteen newborn pigs were nursed by sows for 24 h and then assigned to one of four treatment groups, representing supplementation with 0.0% (control), 0.2% cholesterol, 0.2% DHA, or cholesterol plus DHA to the basal milk-formula. All piglets were euthanized at 49 days of age. In brain, cholesterol supplementation reduced (P < 0.05) concentrations of glutamate, serine, glutamine, threonine, β-alanine, alanine, methionine, isoleucine, leucine, and γ-aminobutyrate but increased (P < 0.05) concentrations of glycine and lysine, whereas DHA supplementation similarly affected (P < 0.05) concentrations of the same AA (except for isoleucine and lysine) and taurine. In addition, concentrations of most AA in liver, muscle and plasma were substantially altered by dietary supplementation of cholesterol and DHA in a tissue-dependent manner. Further, DHA reduced concentrations of carnosine in skeletal muscle, as well as ammonia in both plasma and brain. The results reveal that cholesterol and DHA can regulate AA metabolism and availability in various tissues of piglets. These novel findings have important implications for designing the next generation of infant formula to optimize neonatal growth and development.

l-Arginine stimulates the mTOR signaling pathway and protein synthesis in porcine trophectoderm cells

“…These results indicate that elevated levels of Arg regulate pTr2 cell growth and protein turnover largely via an NO-independent mechanism, as recently reported for intestinal epithelial cells [42]. It is possible that either Arg itself [52,53] or its other metabolites (e.g., polyamines [54]) activate the mTOR signaling to regulate intracellular protein turnover. Additionally, Arg may modulate the production of other signaling molecules (e.g., carbon monoxide and H 2 S [55]) in pTr2 cells.…”

TRIENNIAL GROWTH SYMPOSIUM: Important roles for L-glutamine in swine nutrition and production1,2

“…The synthesis of Gin by the lactating mammary gland must take place to support milk production. After extensive research, Li et al (2009a) recently demonstrated -hat catabolism of BCAA played an important role in Gin synthesis by the lactating porcine mammary glands. However, this biochemical event occurs at the expense of BCAA and, therefore, reduced efficiency in the utilization of dietary AA.…”

Alpha-ketoglutarate inhibits glutamine degradation and enhances protein synthesis in intestinal porcine epithelial cells

“…At the end of 3 h of culture, the medium was removed and cells were washed rapidly three times with phosphate-buffered saline. Cells were then lysed with 0.5 ml of 1.5 M HClO 4 , and the extracts were analyzed for amino acids by HPLC (Li et al 2009b). Concentrations of amino acids in IPEC-1 cells were based on cell volume (0.538 ± 0.036 ll/10 6 cells, mean ± SEM, n = 12), which was determined using 3 H 2 O, as described by Wu and Flynn (1995).…”

“…Concentrations of amino acids and glucose in this special medium are given in Table 1. The medium was changed every 24 h. After 3 days of culture, the medium was collected for analysis of amino acids using HPLC (Li et al 2009b.…”