Regulation of leucine catabolism by caloric sources. Role of glucose and lipid in nitrogen sparing during nitrogen deprivation.

Abstract

Previously we showed that hypocaloric amounts of glucose reduce leucine catabolism while an isocaloric amount of fat does not (1985. J. Clin. Invest. 76:737.) Mmol/100 g per h, P < 0.05). However, all these parameters were significantly lower in lipid-infused than starved rats. There was no significant difference between leucine incorporation into liver and muscle proteins of lipid and glucose-infused rats. On the other hand, starved rats showed a lower leucine incorporation into liver proteins. The data show that under conditions of adequate caloric intake lipid has an inhibitory effect on leucine catabolism but not as great as that of glucose. The mechanism of this difference may be related to a lesser inhibition of muscle protein degradation by lipid than glucose, thereby increasing the leucine pool, which in turn stimulates leucine oxidation.

Effects of in ovo injection of carbohydrates on embryonic metabolism, hatchability, and subsequent somatic characteristics of broiler hatchlings

“…Even though total chick BW on day of hatch was positively related to injection volume for all injectables including diluent, YSW was positively related to fructose, sucrose, or dextrin solution injection volumes, but was not significantly related to diluent, glucose, or maltose injection volumes (Zhai et al, 2011). Previous studies have shown that glucose spares body protein by inhibiting proteolysis, amino acid oxidation, and hepatic gluconeogenesis; however, glucose is not able to stimulate amino acid deposition in muscle protein (Vazquez et al, 1988). Therefore, the inhibitory effects of the in ovo supplemental carbohydrates on nutrient absorption might have surpassed the sparing effects of the carbohydrates on protein degradation.…”

Trajectory and determinants of change in lean soft tissue over the postpartum period

“…However, no difference in polyunsaturated fat intake between women who gained LST and those who lost LST was observed in this cohort. Furthermore, fat intake has also been documented to induce sparing of body nitrogen by a reduction in amino acid oxidation in energy-deficient state ( 36 ) . Any or all of these three effects may have been occurring in some women and could contribute to accrual of LST.…”

Energy nutrients modulate the splanchnic sequestration of dietary nitrogen in humans: a compartmental analysis

“…Such a model provides insight into the dynamics of the system in the nonsteady postprandial state and constitutes a useful, explanatory tool to determine the region-specific utilization of dietary N under different nutritional conditions. protein metabolism; postprandial period; insulin; mathematical model; parameter estimation CONSIDERABLE ATTENTION has been paid to interactions between energy nutrients and nitrogen (N) metabolism, leading to the conclusion that carbohydrate (CHO) is more likely than fat to exert a sparing effect on body protein (25,30,33,42). Certain studies have addressed the effects of dietary CHO (33,48) or insulin availability (32) on splanchnic N anabolism in the fed state, whereas others have aimed at studying the effects of amino acids (AA), CHO, and/or insulin on the stimulation of muscle protein synthesis (5,11,41,44).…”