Liver protein synthesis

Robinson KM, Yarbrough JD. 1980. Liver protein synthesis and catabolism in mirex-pretreated rats with enlarging livers. J Pharmacol Exp Ther215(1) 82-85. 

Price et al. (1996) compared the toxicity of 0.5, 1 and 2 mmol/L coumarin in 24 h cultured precision-cut male Sprague-Dawley rat, Dunkin-Hartley guinea-pig, cyno-molgus monkey and human liver slices. Coumarin toxicity, based on liver protein synthesis and potassium content, was concentration-dependent in rat and guinea-pig liver, whereas monkey and human liver were relatively resistant. 

Changes in liver function tests can occur during estrogen treatment (48). In one comparative study, ethinylestradiol had an unfavorable effect on liver protein synthesis (SED-12,1030) (49). 

Cylindrospermopsin resulted in a hepatotoxic alkaloid that is capable of inhibiting protein synthesis, and it appears to have a progressive effect on several other vital organs snch as the kidney in addition to the liver (Terao 1994 Falconer 1999). Cylindrospermopsin was shown to be a potent inhibitor of protein synthesis. The same stndies described the liver as the main target of this phyco-toxin, with four consecutive phases of the pathological changes in the liver protein synthesis inhibition, membrane proliferation, fat droplet accumulation, and cell death. 

Anthony TG, McDaniel BJ, Byerley RL, McGrath BC, Cavener DR, et al. 2004. Preservation of liver protein synthesis during dietary leucine deprivation occurs at the expense of skeletal muscle mass in mice deleted for eIF2 kinase GCN2. J Biol Chem 279 36553-36561. 

Ohta et al.228 studied whether L-tryptophan would alleviate CCl4-induced chronic liver injury and related dysfunction in rats. Rats received a daily intraperitoneal injection of L-tryptophan (50 mg/kg) for 2 weeks after 6 weeks of subcutaneous injections of CC14 (1 mg/kg) twice weekly. In the rats treated with CC14 alone, the concentration of serum albumin and liver protein and the activity of liver protein synthesis in vitro decreased. The rats that also received L-tryptophan revealed that L-tryptophan alleviated these changes. They speculated that the latter finding alleviated the liver injury changes. 

The polycyclic hydrocarbon type of inducer does not have such major effects, only causing slight liver enlargement and having no effect on liver blood or bile flow. The increase in cytochromes P-450 is not confined to the centrilobular area of the liver, protein synthesis is only slightly increased and there is no increase in phospholipid synthesis. Other enzymes than cytochromes P-450 are also induced by polycyclic hydrocarbons, although generally to a lesser extent than with barbiturate induction. NADPH cytochrome P-450 reductase is not induced by polycyclic hydrocarbons however. 

The liver is the primary site of the synthesis of circulating proteins such as albumin and the clotting factors. When liver protein synthesis is compromised, the protein levels in the blood are reduced. Hypoproteinemia may lead to edema because of a decrease in the protein-mediated osmotic pressure in the blood. This, in turn, causes plasma water to leave the circulation and enter (and expand) the interstitial space, causing edema. 

Nutritional History and Fish Liver Protein Synthesis. 8... 

Upon refeeding, there appears to be a hyper-stimulation of liver protein synthesis levels above those of continuously fed animals. Although both the thyroid hormone (T3) and insulin levels may increase in a similar time scale to the increase... 

THE NUTRITIONAL REGULATION OF TROUT LIVER PROTEIN SYNTHESIS... 

Fig. 8. Summary diagram representing possible changes in circulating hormones, essential amino acid levels and liver protein synthesis with feeding, fasting and refeeding in trout. (McMillan and Houlihan 1990a)...

There have been few studies on the effects of low oxygen levels on protein synthesis rates in fish. Muscle protein synthesis declined in Fundulus heteroclitus when the oxygen level fell (Jackim and LaRoche 1973). In contrast, the rates of liver protein synthesis of trout were similar in water at 100 or 50% air saturation (Fauconneau 1985). 

Haschemeyer AEV (1968) Compensation of liver protein synthesis in temperature acclimated toadfish, Opsanus tau. Biol Bull 135 130-140... 

McMillan DN, Houlihan DF (1990a) The stimulation of trout liver protein synthesis by refeeding involves a rapid and preferential increase in the mitochondrial fraction. (In Preparation)... 

The response to the dietary challenge varies in these animals depending upon whether it is investigated in muscle or liver. Protein synthesis is decreased in muscle but increased in liver. However, the increased rate of protein synthesis in liver is selective. For example, the level of serum albumin synthesized by liver is unchanged, whereas that of glucoproteins is markedly increased. This increase in protein synthesis in associated with an elongation of the size of polysome chains, acceleration of RNA synthesis, and an increase in RNA polymerase activity. The meaning of these observations remains to be understood. 

The mechanisms proposed to be responsible for stress-induced reduction in RBP-ROH levels include redistribution of RBP-ROH into the extravascular space [82], reduction in liver protein synthesis due to increased zinc utilization [77] or due to reduced secretion of hepatic TTR [85], increased urinary excretion of RBP-ROH [86] and increased utilization of plasma retinol by peripheral tissues [87]. While it seems likely that several or all of these mechanisms may be contributing simultaneously, it is clear that the APR results in diminished liver RBP and TTR mRNA levels, and this may represent the primary causative effect that reduces RBP-ROH levels in the circulation. Inflammation induced in rats by turpentine oil [88] or lipopolysac-charide treatment [89, 90] results in a decrease in liver RBP mRNA levels. The decrease in RBP mRNA was accompanied by changes in the circulation parallel decreases in RBP and ROH, and a somewhat delayed decrease in TTR [89]. Interestingly, although kidney RBP and TTR protein concentrations are reduced by inflammation, in contrast to liver, kidney RBP mRNA levels were elevated, thus confirming the earlier observation that regulation of RBP expression is tissue-specific [91]. 

Anthony, T.G., B.J. McDaniel, R.L. Byerley, B.C. McGrath, D.R. Cavener, M.A. McNurlan and R.C. Wek, 2004. Preservation of Liver Protein Synthesis during Dietary Leucine Deprivation Occurs at the Expense of Skeletal Muscle Mass in Mice Deleted for eIF2 Kinase GCN2. J. Biol. Chem. 279, 36553-36561. 

Garlick, P. J., Millward, D, J., and James, W. P, T., 1973, The diurnal response of muscle and liver protein synthesis in vivo in meal-fed rats, Biochem. J. 136 935,... 

Liver protein synthesis (albumin, coagulation proteins), synthesis of cholesterol, triglycerides, and bile salts... 

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