Free Amino Acids In Liver Research Articles

The role of dietary methionine concentrations on growth, metabolism and N-retention in cobia (Rachycentron canadum) at elevated water temperatures.

This study determined impacts of dietary methionine concentrations at two temperatures on growth, feeding efficiency and N‐metabolites in juvenile cobia. Methionine concentrations of the experimental diets were deficient (M9; 9 g/kg), sufficient (M12; 12 g/kg) and surplus (M16, 16 g/kg). Water temperature was normal (30°C) or elevated (34°C). Twenty cobia in triplicate tanks were fed the experimental diets for 6 weeks. Both methionine and temperature affected cobia's growth and feeding efficiency. Cobia fed M9 performed lower than the fish fed M12 and M16 diets. Additionally, cobia reared at 34°C performed poorer than at 30°C, probably due to lower voluntary feed intake in the fish reared at 34°C. Protein efficiency ratio and protein productive value in cobia fed M9 diet were less than M12 or M16 diets. This was confirmed with the improved retentions of indispensable amino acids (AAs). No interactions between methionine and temperature were observed in growth and protein accretion. At 30°C, CF improved, while HSI and VSI declined upon methionine supplementation levels. Of which an interaction between temperature and methionine was present. Plasma, muscle and liver free AA and N‐metabolites were affected by methionine and temperature. Furthermore, temperature affected cobia's lipid class composition, resulting in increased phospholipids and cholesterol at 34°C.

Toxicity of Triphenyltin Hydroxide to Fish

Triphenyltin (TPhT) is used worldwide in pesticide formulas for agriculture. Toxic effects of this compound to aquatic life have been reported; however, the biochemical response of fish exposed to different concentrations of TPhT hydroxide (TPhTH) was investigated for the first time in this study. The lethal concentration (LC50) of TPhTH to silver catfish, Rhamdia quelen, was calculated from an acute-exposure experiment (96h). In addition, acethylcholinesterase (AChE) activity in brain and muscle-as well as glucose, glycogen, lactate, total protein, ammonia, and free amino acids in liver and muscle-were evaluated in a chronic-exposure experiment (15-day exposure). Speciation analysis of tin (Sn) was performed in fish tissues at the end of both experiments using gas chromatography coupled to a pulsed-flame photometric detector (GC-PFPD). Concentrations of TPhT, diphenyltin, and monophenyltin (reported as Sn) were lower than limits of quantification (10σ criteria). Waterborne TPhTH concentration used through the experiment was also evaluated by GC-PFPD, and no degradation of this species was observed. The LC50 value for silver catfish juveniles was 9.73μgL(-1) (as Sn). Decreased brain and muscle AChE activities were observed in fish exposed to TPhTH in relation to unexposed fish (control). Liver glycogen and lactate levels were significantly higher in fish kept at the highest waterborne TPhTH concentration compared with the control. Liver and muscle glucose levels of fish exposed to all TPhTH concentrations were significantly lower than those of control fish. Silver catfish exposed to all TPhTH concentrations showed lower total protein values and higher total free amino acids levels in liver and muscle compared with controls. Total ammonia levels in liver and muscle were significantly higher for the highest TPhTH concentration compared with controls. In conclusion, TPhTH caused metabolic alterations in silver catfish juveniles, and the analyzed parameters can also be used as bioindicators for TPhTH contamination.

Changes in tissue free amino acid pools in growing chickens fed thermally treated vetch diets

A three-day assay was developed to evaluate the effect of autoclaving on protein quality of vetch as an alternative to classical growth methods. Male chickens (n = 10/diet) were given approximately isonitrogenous diets based on raw or autoclaved vetch for 3 days. Samples of plasma, muscle and liver were obtained for free amino acid analysis. Heating vetch depressed growth (11.9 vs. 23.2 g/d; p < 0.05). Plasma methionine and histidine increased (0.05 < p < 0.06), while gluconeogenic amino acids tended to decrease (p < 0.10) after heating. Muscle free amino acids did not change except for a trend to increased methionine (p = 0.06) in birds fed autoclaved vetch. In liver, most essential amino acids, glycine, proline and tyrosine increased markedly with heated vetch diet. Correlations between plasma and muscle free amino acids were poor compared with those between plasma and liver free amino acids. Liver free amino acid pool was more sensitive than muscle or plasma pool to amino acid inflow modifications after vetch heating.

Effect of N-stearoylethanolamine on free amino acid levels in rat plasma and liver with burn

The effect of the endocannabinoid congener N-stearoylethanolamine (NSE) on the content of plasma and liver free amino acids in burned rats was studied. The animals after the thermal burn of the skin received per os during 7 days the water suspension of NSE in the doze 10 mg/kg of body weight. In the other group of rats the suspension was applied on the wound (the concentration of NSE was 10 mg/ml). In experimental animals the total amount of free amino acids in plasma decreased after burn while the total amount of free amino acids in liver significantly increased. In burn animals the ratio of plasma and liver Phe/Tyr and Gly/Val was found to be augmented while the Fischer ratio (Ile+Leu+Val/Phe+Tyr) diminished compared with intact rats. It was shown for the first time that NSE caused normalization of the concentration of some free amino acids and of Phe/Tyr, Gly/Val ratios, and the Fischer ratio in blood plasma and liver of rats with the burn injury. Altogether, these data demonstrate that NSE possesses adaptogenic properties, and is involved in the organism response to a burn. These findings suggest possibility of NSE usage for burn treatment.

Some physiological studies on the effect of onion and garlic juices on the fish, Clarias lazera

Fish, Clarias Lazera were orally administered onion (Allium cepa) or garlic (Allium sativum) juices. Contents of glucose, free amino acids, total lipids, triglycerides, cholesterol, albumin, total protein, urea, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum as well as glycogen, free amino acids, total lipids, triglycerides and cholesterol contents in liver, white and red muscle were determined 5 h and 24 h after a single dose or after repeated doses (1 dose every 24 h for 5 days). Both onion and garlic treatments caused a temporary hypoglycemia as well as liver glycogen muscle depletion accompanied with a significant elevation in white muscle glycogen suggesting that dietary onion or garlic may enhance the process of glycogenesis in white muscle. Onion feeding caused hypolipidemia accompanied with significant decreases in liver content of total lipids in response to the repeated doses for 5 days and a severe rise in the lipid content of red muscle at all periods. Such results suggest that dietary onion may enhance the process of lipogenesis in red muscle of Clarias lazera. Probably, the main precursor of such lipogenesis in the red muscle was the serum fatty acids. Moreover, dietary onion led to hypocholesterolemia accompanied with a significant rise in cholesterol level of both liver and red muscle. On the other hand, dietary garlic significantly decreased serum free amino acids after 5 h and 5 days. Furthermore, significant elevations of liver free amino acids were dedected in the onion-treated fish group (24 h and 5 days) and in the garlic-treated fish group (5 h), probably due to oxidation of thiol components (sulfur attached to the proteins). This result was accompanied with either a marked increase in white muscle free amino acids at all periods of garlic fish group, or a noticeable drop in the onion group (repeated doses). Also, dietary onion and garlic treatment led to an elevation in hepatic ureagenesis in spite of the unchanged serum urea level. Significant decreases of both serum AST and ALT in garlic groups (all periods) and in onion groups (repeated doses) were observed. In liver, AST and ALT showed temporary rises after onion or garlic supplementation. In general, it could be concluded that both dietary onion and garlic have a transitory hypoglycemic action as well as a promoting effect on the process of glycogenesis in white muscle whereas dietary onion promotes lipogenesis in red muscle of fish. Also, dietary garlic may enhance the white muscle uptake of free amino acids which, in turn, may promote protein synthesis.

Primed, constant infusion with [2H3]serine allows in vivo kinetic measurement of serine turnover, homocysteine remethylation, and transsulfuration processes in human one-carbon metabolism

One-carbon metabolism involves both mitochondrial and cytosolic forms of folate-dependent enzymes in mammalian cells, but few in vivo data exist to characterize the biochemical processes involved. We conducted a stable-isotopic investigation to determine the fates of exogenous serine and serine-derived one-carbon units in homocysteine remethylation in hepatic and whole-body metabolism. A healthy man aged 23 y was administered [2,3,3-(2)H(3)]serine and [5,5,5-(2)H(3)]leucine by intravenous primed, constant infusion. Serial plasma samples were analyzed to determine the isotopic enrichment of free glycine, serine, leucine, methionine, and cystathionine. VLDL apolipoprotein B-100 served as an index of liver free amino acid labeling. [(2)H(1)]Methionine and [(2)H(2)]methionine were labeled through homocysteine remethylation. We propose that [(2)H(2)]methionine occurs by remethylation with [(2)H(2)]methyl groups (as 5-methyltetrahydrofolate) formed only from cytosolic processing of [(2)H(3)]serine, whereas [(2)H(1)]methionine is formed with labeled one-carbon units from mitochondrial oxidation of C-3 serine to [(2)H(1)]formate to yield cytosolic [(2)H(1)]methyl groups. The labeling pattern of cystathionine formed from homocysteine and labeled serine suggests that cystathionine is derived mainly from a serine pool different from that used in apolipoprotein B-100 synthesis. The appearance of both [(2)H(1)]- and [(2)H(2)]methionine forms indicates that both cytosolic and mitochondrial metabolism of exogenous serine generates carbon units in vivo for methyl group production and homocysteine remethylation. This study also showed the utility of serine infusion and indicated functional roles of cytosolic and mitochondrial compartments in one-carbon metabolism.

A comparison of transport-related gill enzyme activities and tissue-specific free amino acid concentrations of Baltic Sea (brackish water) and freshwater threespine sticklebacks, Gasterosteus aculeatus , after salinity and temperature acclimation

The osmoregulatory abilities of one freshwater and two brackish water (Baltic Sea) populations of the euryhaline teleost fish Gasterosteus aculeatus were studied with respect to evolutionary physiology. Plasma osmolality, activities of Na+K+-ATPase, citrate synthase, creatine kinase in the gill and free amino acids in liver, axial muscle and pectoral fin muscle were measured. After transfer from 10 to 35 ppt at 15 °C, time-course changes of plasma osmolality and gill Na+K+-ATPase showed no significant fundamental differences between the freshwater and one of the Baltic Sea populations. In a multi-factorial experiment, each population was exposed to four different abiotic regimes. Both brackish water populations had high mortality in freshwater at 4 °C, which is discussed as a failure of osmotic regulation (reduced taurine concentrations). Freshwater specimens had higher levels of glycine in the axial and pectoral fin muscles compared to the brackish water populations. This is interpreted as a genetically based effect. In brackish (20 ppt) water of 15 °C, the freshwater population had high activities of Na+K+-ATPase, but low activities of creatine kinase, whereas both brackish water populations behaved in the opposite way. A fundamental difference between the freshwater and brackish water populations on the level of the osmoregulatory machinery was not observed.

Metabolic response of liver lysine α-ketoglutarate reductase activity in rats fed lysine limiting or lysine excessive diets

The effects of feeding isonitrogenous diets (at a restricted ration size), containing limiting or excessive amounts of lysine on various biochemical parameters of rats were investigated. Lysine α-ketoglutarate reductase (LKGR) and citrate synthase (CS) activities, hepatic portal vein (HPV) blood and liver free amino acid concentrations were measured in rats fed the experimental diets for up to 8 days. LKGR and CS activities remained constant in rats adapted to the lysine limiting diet. In contrast, LKGR activity rapidly increased (after 2 days) in rats fed the lysine excess diet and remained at a high level for the remainder of the experiment. The increase in liver LKGR activity in response to the lysine excess diet was associated with significant increases in HPV and liver free lysine concentrations (4.5- and 2-fold, respectively). The significance of these data are discussed with respect to the metabolic response of rats challenged with an increased lysine supply and its effects on free lysine concentrations and liver LKGR activity.

Mouse liver free amino acids during the development of Ehrlich ascites tumour

Sequential amino acid concentrations were determined in the liver of mice infested with a highly malignant strain of Ehrlich ascites tumour cells. The liver concentrations of a certain group of amino acids showed changes consistent with those previously reported for plasma, ascitic liquid and tumour cells during tumour growth. Shortly after tumour transplantation a significant decrease of the essential amino acids methionine, threonine, valine, isoleucine + phenylalanine, leucine, lysine and histidine, was detected. Some non-essential amino acids, mainly the gluconeogenic substrates alanine and serine, showed a strong reduction in hepatic concentrations during the first days; these amino acids remained significantly lower than controls until animal death. Interestingly, hepatic glutamine increased at days 1 and 2 after inoculation, and proline showed a sustained increase from the seventh day onwards, reaching a value double the control at the end of animal life.

Zur Wirkung unterschiedlicher Proteindiäten auf Lebensdauer und ausgewählte biochemische Parameter von alten Ratten

In this work 23 month old rats were fed for 200 days with different protein diets (NT-diet: 19% protein, 72% of animal origin and LP-diet: 8.8% protein exclusively of vegetable origin). Some metabolic parameters and lifespan (on the base of a 50% death-rate) were determined. The relations of the liver free amino acids glycine + alanine and tyrosine + phenylalanine + branched chain amino acids and the ratio of phenylalanine/tyrosine were determined to be higher in the LP-group. Phenylalanine in liver and urea concentrations in liver and serum were lower in the LP-group. Furthermore the dopamine or serotonin levels were significantly lower in lateral and medial or lateral regions of the hypothalamus respectively in LP-diet fed rats. The norepinephrine content was not modified by the diets. The median lifespan of 23 month old rats was higher by 24% following LP-treatment. These results suggest that the protein component (amino acids) of different diets may modify metabolic parameters and lifespan of animals by mechanisms in which the central regulation may be involved.

Plasma and liver free amino acids in rats fed glycine supplemented casein diets

Differences in the amino acid composition appear to be largely responsible for various actions of food proteins of vegetable or animal origin on lipid metabolism and atherogenesis. But it remains still unclear which amino acids or combinations of amino acids are mainly influencing the physiologic effects observed by mechanisms which has yet to be satisfactorily explained [1-3]. Glycine has been shown to modify lipid metabolism in liver and blood lipid parameters significantly when supplemented to casein diets alleviating in some studies hypercholesterolemia and atherosclerosis [3–5]. The present study investigates the effects of glycine supplemented casein diets on plasma and liver free amino acid patterns. The findings to be presented here support the possible role of amino acids in respect of modifying the risk factors for arteriosclerotic complications.

Influence de l'ingestion de lactose sur le métabolisme protéique de l'agneau nouveau-né

Whole body and tissue protein turnovers were measured in 6 newborn lambs taken from their mothers immediately after birth. Three lambs (AJ) were hourly fed 50 ml of saline (NaCl 0.9%), and 3 (AL) were fed, on the same schedule, 50 ml of saline with 2.25 g of lactose added. They were continuously infused L-[4,5(3)H]-leucine for 6 h when they were 2 h 30 min old. Plasma glucose and insulin were higher in AL than in AJ lambs. On the contrary, the lowest plasma levels of free threonine, valine, isoleucine, leucine, phenylalanine, lysine, histidine, serine and alanine occurred in the lactose-fed lambs (table 1). The concentrations of most free amino acids in liver, brain, small intestine and muscle (Longissimus dorsi) were not significantly different (fig. 1). The irreversible loss of plasma leucine did not differ (mean +/- SD : 160 +/- 47 and 156 +/- 11 micro moles/h/kg for AL and AJ lambs, respectively). The leucine catabolic rate was higher in AJ than in AL lambs (22.4 +/- 2.8 vs 17.9 +/- 1.7%). The fractional rates of protein synthesis in the liver, small intestine and brain were not significantly different between AL and AJ lambs; these rates were higher in the muscle, lungs and whole body of the AL lambs (table 2).

Liver- and muscle amino-acid concentrations during the development of domestic fowl

The concentrations of free amino acids in liver, leg muscle and wing muscle of developing domestic fowl chicks were measured and compared with those of adults. Leg and breast muscles showed a remarkably parallel pattern of change in free-amino-acid concentrations during development up to day 5 after hatching, in agreement with their lack of differentiation up to day 5. Liver free-amino-acid concentration pattern with the development were very similar to those of the muscles, in significant difference with Mammals. Adult free tissue amino acids were lower than those of developing chicks. Most changes in amino-acid concentration in chick tissues were observed around hatching, and have been tentatively attributed to changes in diet. Combined amino acids changed very little during the period studied in muscles and liver. Taurine constituted a very big share of total amino acids.

Liver free amino acid (AA) pattern in cancer patients : [formula omitted], M. Thomas, R. Abele, P. Fürst (Center of Surgery, Justus-Liebig-University of Gießen, FRG and Inst. Biol. Chem. and Nutr., Univ. Hohenheim)

Liver free amino acid (AA) pattern in cancer patients : [formula omitted], M. Thomas, R. Abele, P. Fürst (Center of Surgery, Justus-Liebig-University of Gießen, FRG and Inst. Biol. Chem. and Nutr., Univ. Hohenheim)

Changes in plasma, tissue, and urinary nitrogen metabolites due to an inflammatory challenge.

Studies were undertaken to define the changes in protein metabolism that result from stimulation of the immune system by noninfectious inflammatory agents. Chicks were injected with inflammatory agents and metabolite concentrations were determined between 4 and 48 hr postchallenge. Inflammatory agents resulted in a generalized decrease in the concentration of plasma nitrogen metabolites, including ammonia, uric acid, urea, and several amino acids. Escherichia coli and sheep red blood cell (SRBC) injections induced changes in the concentrations of tissue-free amino acids at 16 hr postchallenge. After E. coli injections, free amino acid concentrations were increased by 175% in muscle and decreased by approximately 25% in liver, spleen, and bursa. A SRBC challenge resulted in similar decreases in free amino acid concentrations in the spleen and bursa as did E. coli; however, muscle and liver free amino acid concentrations were mostly unchanged. Urinary ammonia was increased, urinary uric acid was decreased, and urinary amino acids were not affected by E. coli injection. These findings indicate that stimulation of the immune system by noninfectious inflammatory agents induces tissue-specific changes in nitrogen metabolism. Changes in amino acid pool sizes in various tissues suggest alterations in rates of protein synthesis or degradation.

Quantitative changes in aminoacylation of transfer RNA and in free amino acids during fructose-induced depletion of adenine nucleotides in rat liver

Fructose induces depletion of adenine nucleotides in liver and also strongly inhibits incorporation of radioactive amino acids into protein (Mäenpää, P.H., Raivio, K.O. and Kekomäki, M.P. (1968) Science 161, 1253–1254). In this study we have investigated the effects of fructose on aminoacylation of tRNA and on free amino acids in rat liver. 30 min after d-fructose (30 mmol/kg) was injected intraperitoneally into rats, liver ATP was reduced by 58%, ADP by 42%, AMP by 13%, the ATP/ADP ratio by 30%, and total adenine nucleotides by 48%. Using gas chromatography, the aminoacylation of tRNA was determined by quantifying the endogenous amino acids attached to tRNA in vivo. Aminoacylation was reduced by 31%. With different amino acids, reduction varied from 4% (asparagine plus aspartic acid) to 58% (arginine). On the other hand, the amount of free amino acids in the liver was increased by 24%. The most marked individual change was in alanine, which increased 5.7-times. This may have resulted from a combination of effects involving an increased production of alanine in muscle and liver and decreased hepatic gluconeogenesis from alanine caused by the ATP depletion.

Circadian Variations of Liver Free Amino Acid Content in Mixed-Fed and Protein-Meal-Fed Rats

Hepatic amino acid contents were determined at time-points regularly spaced over a light-dark cycle in rats fed either a 12% casein diet or a single daily meal given 2 hours after the onset of the light phase with a protein-free diet ad libitum. In mixed-fed rats, non-essential amino acid hepatic content remained stable over 24 hours while that of essential amino acids rose during the early part of the night in connection with the onset of prandial activity, but long before portal levels increased. The possibility of factors related to food intake (insulin, glucagon, gastrointestinal hormones) or to its chronology (corticoids) stimulating active transport is discussed. In separately-fed rats, amino acid pools increased in the 30 minutes following protein administration in connection with rising portal levels. During the rest of the light phase, a general depletion of non-essential amino acids occurred. It was most rapid for glutamine, alanine and aspartic acid and was followed by accumulation during the night phase, a pattern fitting well with gluconeogenesis and ureogenesis stimulation following protein ingestion. Essential amino acid decrease was linear and spanned over both the light and dark phases in correlation with decreasing portal levels.liver amino acids circadian variations

The physiological and biochemical responses of broilers exposed to short-term thermal stress

1. 1. Exposure of cockerels to heat stress (42°C) for 15 min resulted in a reduction of both the total free and essential free amino acids in plasma with simultaneous elevation in the levels of the total free and essential free amino acids in liver as compared to the pre-stress level. 2. 2. The reduction in the plasma free amino acid pools was accompanied by a decrease in total proteins and alkaline phosphatase concentrations, with a simultaneous elevation in albumin, glucose, uric acid, plasma free fatty acids, lactate dehydrogenase and creatine kindase. 3. 3. During the recovery period both the total plasma and hepatic free amino acids returned to prestress levels but the levels of the essential plasma free amino acids in heat-stressed birds remained low while the hepatic essential free amino acids remained high. 4. 4. At the end of a 30 min recovery period at 21°C, the glucose content substantially decreased with free fatty acids and uric acid still remaining at high levels. 5. 5. There was a significant reduction in nitrogen retention in heat-stressed birds determined during the 24 hr recovery period mainly due to an increase in the excretion of nitrogen in uric acid form. 6. 6. In birds exposed to cold (4°C), the only significant changes were an increase in the hepatic essential free amino acids and an increase in uric acid excretion. 7. 7. The results indicate that short-term heat stress affects protein metabolism in growing chickens.

Effect of Dietary Proteins and Amino Acid Deficiencies on Urinary Excretion of Nitrogen and the Urea Synthesizing System in Rats

A mechanism of regulation in urea biosynthesis under conditions of varying dietary protein quality was investigated in rats adapted to 10% protein diets. A reverse correlation was observed between activities of urea cycle enzymes and urinary excretion of urea under these conditions. The concentrations of several non-essential amino acids in livers of rats fed a 10% gluten diet significantly increased as compared with those of rats fed a 10% whole egg protein diet without change in ornithine concentration. The contents of threonine, serine and ornithine in livers of rats fed a methionine-free diet were higher than those of rats fed a basal diet. The capacity of urea synthesis in vivo of rats fed gluten or a methionine-free amino acid mixture was the same as that of rats fed whole egg protein or basal amino acid mixture. The results suggest that under conditions of varying dietary protein quality, the liver level of free amino acids may regulate mainly the rate of urea synthesis without changes in activities of urea cycle enzymes and that the concentrations of ornithine in addition to free amino acids in liver may play an important role in an increase of urea synthesis in the methionine-deficiency.

Effects of alloxan diabetes and hypophysectomy on growth, and plasma and liver free amino acids of rats fed excess glycine diets.

Effects of alloxan diabetes and hypophysectomy on growth, and plasma and liver free amino acids of rats fed excess glycine diets.