The isoelectric fractionation of hen''s-egg ovotransferrin

1. ATP sulphurylase was assayed in various organs from vitamin A-deficient and pair-fed control rats at different stages of deficiency. Activity decreased slightly in the liver and markedly in the adrenal gland. Striking differences in liver activity were observed between pair-fed control and ad libitum-fed animals. This observation suggested that diet (apart from vitamin A) strongly influenced the activity of ATP sulphurylase. 2. Total starvation caused a severe decrease in activity in liver within 48hr. This was due to a lack of protein intake. 3. By feeding groups of vitamin A-deficient and pair-fed control rats on a diet containing 80% protein, the specific activity of the liver ATP sulphurylase was maintained in the pair-fed control group at the normal level of an ad libitum-fed rat, whereas it decreased by 25% (statistically significant at P<0.01) in the deficient rat. On a 20%-protein diet, there were no significant differences between vitamin A-deficient and pair-fed control rats. These relationships held also for enzyme activity expressed per g. of liver, per total liver and per g. of DNA. There were no differences in liver protein or DNA concentration between vitamin A-deficient and control rats on either protein intake. 4. Control rats on a 20%-protein diet had liver specific enzyme activities about one-half of those in control rats on an 80%-protein diet, as well as lower liver protein concentrations. 5. It is concluded that, when the effect of protein deprivation on ATP sulphurylase is separated from the effect of vitamin A deficiency, a lowering of the enzyme activity caused by the vitamin deficiency is demonstrable.     

Effect of high- and low-protein diets on the regulation of rat liver tyrosine aminotransferase and tryptophan oxygenase activities by l-tyrosine and l-tryptophan

Induction of rat liver tyrosine aminotransferase by l-tyrosine and tryptophan oxygenase by l-tryptophan was studied in groups of rats fed on diets containing 18 or 5% protein. The basal activity of hepatic tyrosine aminotransferase of rats receiving 5% protein gradually increased with the age of the animals but that of rats receiving 18% protein did not. l-Tyrosine induced hepatic tyrosine aminotransferase in rats receiving 18% protein when tested at ages from 4 to 20 weeks. When induction by l-tyrosine was carried out in rats receiving the 5% protein diet, significant induction of tyrosine aminotransferase occurred only in 4- or 6-week-old rats. Induction by l-tryptophan of tryptophan oxygenase in liver or the basal activity of this enzyme in liver did not differ between the groups fed on 5 and 18% protein. On changing the diet from 0 to 18% protein, the above-mentioned effects on the induction of hepatic tyrosine aminotransferase were reversed.     

Dietary whey protein modulates liver glycogen level and glycoregulatory enzyme activities in exercise-trained rats

This study compared the effects of dietary whey protein with dietary casein or soy protein on glycogen storage and glycoregulatory enzyme activities in the liver of sedentary and exercise-trained rats. Male Sprague-Dawley rats (ca. 130 g) were divided into one sedentary and three exercise-trained groups, with eight animals in each group. Casein was provided as the source of dietary protein in the sedentary group while the exercise-trained groups were fed casein, whey, or soy protein. Rats in the exercise-trained groups ran for 30 mins/day, 4 days/week on a motor-driven treadmill. In the exercise-trained rats, animals fed whey protein had higher liver glycogen content than animals in the other two diet groups. Glucokinase activity was significantly higher in rats fed whey protein compared to that in rats fed soy protein, while glucose 6-phosphatase activity was significantly decreased in animals on the whey protein diet compared with those the other two diets. Although 6-phospho-fructokinase activity was significantly lower in the whey protein group than in the soy protein group, we found that fructose 1,6-bisphosphatase activity was significantly higher in the whey group compared with either the casein or soy groups. Pyruvate kinase activity in rats fed the casein diet was significantly higher than in rats fed either the whey or soy protein diets. In addition, hepatic alanine aminotransferase activity and serum alanine level were also increased in the whey protein group compared with the casein or soy protein groups. Taken together, these results demonstrate that the whey protein diet in exercise-trained rats results in significantly higher levels of liver glycogen, because of the combined effects of regulation of rate limiting glycolytic and gluconeogenic enzyme activities and activation of glycogenesis from alanine via alanine amino-transferase.     

Effects of dietary protein intake on branched-chain keto acid dehydrogenase activity of the rat. Immunochemical analysis of the enzyme complex

Polyclonal antibodies directed against the dihydrolipoyl transacylase (E2) and alpha subunit of branched-chain alpha-keto acid decarboxylase (E1 alpha) components of the bovine branched-chain keto acid dehydrogenase complex were shown to cross-react with the E2 and E1 alpha polypeptides of the enzyme complex of different rat tissues. Phosphorylation of the branched-chain keto acid dehydrogenase complex resulted in inhibition of enzyme activity concomitant with phosphate incorporation into the E1 alpha polypeptide. Phosphorylation of E1 alpha slowed its rate of migration through sodium dodecyl sulfate-polyacrylamide gels. This permitted resolution of the phosphorylated and unphosphorylated forms of E1 alpha on immunoblots. Liver and skeletal muscle mitochondria were prepared from rats consuming 6, 20, or 50% casein diets. The enzyme complex in mitochondria was measured by radioisotopic enzyme assay and immunoassay. Liver branched-chain keto acid dehydrogenase was 25% active in rats consuming 6% casein diets; whereas in rats consuming 20 or 50% casein diets, the liver enzyme was 82 or 100% active, respectively. Branched-chain keto acid dehydrogenase of muscle was 10, 13, and 22% active, respectively, in rats consuming 6, 20, and 50% casein diets. The amount of protein consumed by rats did not affect the total amount of the enzyme complex per unit of mitochondrial protein as measured by either the radioisotopic assay (enzyme activity) or the immunoassay. However, the protein intake of rats did affect activity of the enzyme kinase in liver. Liver branched-chain keto acid dehydrogenase kinase was more active in rats consuming 6% casein than in those fed chow or 50% casein diets. The amount of protein consumed by rats thus influences the enzyme activity in liver and muscle by affecting the reversible phosphorylation mechanism and not by induction of branched-chain keto acid dehydrogenase.     

Effect of realimentation after several days' pure carbohydrate intake on DNA synthesis in regenerating rat liver

The authors studied the effect of realimentation after several days' isolated glucose or fructose intake on DNA synthesis in liver regenerating after partial hepatectomy (PH) (65-70%) or after carbon tetrachloride (CCl4) poisoning 1.5 ml/kg. Two days before PH or the administration of CCl4 and two days after, the experimental rats were given glucose (50% solution) of fructose (50% solution) as the only source of energy. Rats with PH were then fed for one day on a standard laboratory diet (25 cal% protein) or a high protein diet (81 cal% protein). Rats with CCl4 liver damage were fed for one day on the standard laboratory diet only. In the rats given glucose, liver DNA synthesis and the total amount of these nucleic acids in the liver 48 hours after CCl4 administration was lower than in the controls or the rats given fructose. In all the experimental groups (PH and CCl4), stimulation of liver DNA synthesis was observed after one day's realimentation. The total DNA content of the liver of rats with PH rose markedly during realimentation. The experiments indicate that the regenerative activity of damaged liver can be influenced by the nutritional regimen.     

Effects of dietary nutrients on lipogenic enzyme and mRNA activities in rat liver during induction

By feeding a carbohydrate diet (without protein) to fasted rats, malic enzyme mRNA activity in the liver was increased to the level in rats fed a carbohydrate and protein diet, whereas the enzyme activity itself was increased to 60% of that level. It appears that malic enzyme mRNA activity was increased by dietary carbohydrate, while dietary protein contributed to an increase in the translation of mRNA. In the animals fed carbohydrate without protein, glucose-6-phosphate dehydrogenase mRNA activity increased to 50% of the level in rats fed the carbohydrate and protein diet, whereas the enzyme activity increased to only 25%. By feeding a protein diet (without carbohydrate), glucose-6-phosphate dehydrogenase activity increased to 65% of the level in rats fed both carbohydrate and protein. This enzyme induction appears to be more dependent on protein than carbohydrate. With the carbohydrate diet, acetyl-CoA carboxylase was induced up to the level in the carbohydrate and protein diet group, whereas fatty acid synthetase was induced to only 33%. Acetyl-CoA carboxylase induction appears to be carbohydrate dependent. On the other hand, isotopic leucine incorporation studies showed that the magnitudes of the enzyme inductions caused by the dietary nutrients should be ascribed to the enzyme synthesis rates rather than the degradation. By fat feeding, the mRNA activities of malic enzyme and glucose-6-phosphate dehydrogenase were markedly decreased along with the enzyme induction. Fat appears to reduce these enzyme inductions before the translation of mRNA.     

Effect of dietary proteins on the turnover of rat liver argininosuccinate synthetase.

The rates of synthesis and degradation of arginosuccinate synthetase in rat liver under various dietary conditions were determined. The relative rate of the enzyme synthesis in the livers of rats fed on 70% casein diet was 4.0 times greater than that for rats fed on 5% casein diet. The rate constants of degradation (Kd of argininosuccinate synthetase were estimated to be 0.15 and 0.16 day-1 under 70% and 5% casein feeding, respectively. When the dietary conditions were changed acutely from 70% to 5% casein diet or vice versa, the rates of the enzyme synthesis decreased or increased, respectively, and the rates of enzyme degradation were also affected. The change from 5% to 70% casein diet caused a transient decrease in the rate of degradation. After the enzyme activity had achieved a new steady-state level, the enzyme degradation proceeded at the normal steady rate. On the other hand, the change from 70% to 5% casein diet caused a transient increase in the rate of degradation. Thus, the only factor regulating the amount of enzyme in rat liver is the rate of enzyme synthesis under the steady-state conditions. However, the rates of both enzyme synthesis and degradation are involved in the regulation of the amount of enzyme during dietary transition.     

Induction of rat liver glycine methyltransferase by high methionine diet

Dietary experiments were carried out to evaluate the physiological role of glycine methyltransferase. When rats received a 18% casein diet containing excess methionine, the activity of the enzyme in liver extracts increased with increasing methionine content in the diet. Adenosylmethionine synthetase and adenosylhomocysteinase activities were also elevated, while guanidoacetate methyltransferase activity showed no significant change. The glycine methyltransferase activity reached a maximal level after 4–6 days on the 3% methionine diet. Immunological titration showed that the increase in activity was associated with the increase in amount of the enzyme.     

Protein utilization in correlation to protein intake

In a 14-day experiment, weaned and adult rats were given ad libitum isocaloric diets with a mounting casein content (5, 10, 15, 25 and 40% by weight) and growth parameters of protein biological value, PER and NPR, and the utilization parameters NPU (body protein) and LPU (liver protein) were determined together with phosphoenolpyruvate carboxykinase (gluconeogenetic enzyme) and pyruvate kinase (glycolytic enzyme) activity in the animals' liver. The decrease in all the biological value parameters in weaned rats on 25% and 40% casein diets and in adult rats on 15%, 25% and 40% casein diets shows that these concentrations are too high for the organism. The decrease in PER and diminished weight and body and liver nitrogen increments in both age groups in animals with a low protein intake is evidence that 5% casein is an inadequate concentration. The optimum diet for weaned rats is thus a 15% casein diet and for adult rats a 10% casein diet, as confirmed by the linear correlation between weight increments, body and liver nitrogen and protein intake and also by gluconeogenetic enzyme activity. Under the given experimental conditions the study is a contribution to the determination of optimum physiological doses of proteins.     

Differential effect of sunflower seed oil on hepatic and renal D-amino acid oxidase in the rat.

1. The specific activity of hepatic and renal peroxisomal D-amino acid oxidase (D-AAOX) was measured in rats fed diets containing various quantities of vegetable oil. 2. Increasing the amount of dietary sunflower seed oil (SSO) from 10 to 25% (w/w) reduced the specific activity of hepatic D-AAOX by up to 30% after 10 days. 3. In both tissues, the enzyme activity was moderately decreased during the first two-day period after administration of the 25% SSO diet was begun. Unlike hepatic D-AAOX, renal D-AAOX returned to its baseline level in the kidney after the third day. 4. In contrast to SSO, hydrogenated coconut oil (HCO) did not evoke alterations of D-AAOX activity. 5. The activity levels of another peroxisomal enzyme, L-2-hydroxy acid oxidase (L-HAOX), in the liver of rats fed the high-SSO diet vs those fed the control diet were similar. 6. The subcellular distribution of D-AAOX and L-HAOX was not altered in the liver of rats fed the 25% SSO diet during the 10-day period.     

Deoxyribonucleic acid-dependent ribonucleic acid polymerase activity in rat liver after protein restriction.

Rats were fed for 6 days on a diet containing either 3 or 20% high-quality protein. Nuclei were isolated from liver and DNA-dependent RNA polymerases (EC 2.7.7.6) extracted with 1 M-(NH4)2SO4. The proteins were then precipitated with 3.5 M-(NH4)2SO4 and after dialysis applied to a DEAE-Sephadex column. The column was developed with a gradient of (NH4)2SO4. Polymerase I separated well from alpha-amanitin-sensitive polymerase II. The enzyme activities were compared between the two dietary groups. Rats that had received 3% protein showed a lower polymerase I activity per g wet wt. of liver, per mg of DNA and per mg of protein. Polymerase II was lower in activity per g wet wt. of liver and per mg of DNA, but was higher per mg of protein. Polyacrylamide-gel electrophoretograms showed a higher proportion of contaminating proteins in polymerase II fractions isolated from 20%-protein-fed rats. The data explain the lower activity obtained per mg of protein in these rats. It is concluded that a decrease in dietary protein content from 20 to 3% induces a fall in content and specific activity of RNA polymerase I and II in liver.     

The in vitro stability of rat liver glucose-6-phosphate dehydrogenase as a function of diet

Rat liver glucose-6-phosphate dehydrogenase (G6PD) activity was studied in starved-refed rats given diets containing three levels of fat (35%, high-fat; 5%, low-fat; 0%, fat-free). Elution characteristics from DEAE-cellulose, Km for glucose-6-phosphate, pH optimum, and molecular weight appeared to be similar. During storage or heat denaturation, stability apparently was lowest of G6PD of livers from rats refed the high-fat diet. Heat stability was enhanced by the addition of NADP, but some differences due to diet persisted. Titration of a constant amount of enzyme with heating gave inconsistent results: in two of four experiments rats refed the high-fat diet had an equivalence point twice that of rats refed the fat-free diet. This difference disappeared if the antibody titration was carried out in the cold. The diet-induced instability of the G6PD, as measured in vitro, was reversible by changing the diet of the rats.     

Short-term effect of a high-protein/low-carbohydrate diet on aminopeptidase in adult rat jejunoileum. Site of aminopeptidase response.

The short-term effects of high-protein/low-carbohydrate diet on aminopeptidase N activity were studied in the brush-border membranes of proximal jejunum and proximal ileum of adult rats. The animals were starved overnight and re-fed for 15 h either with a standard diet (20% protein, 55% carbohydrate, in terms of energy content) or with a high-protein/low-carbohydrate diet of equal energy content (70% protein, 5% carbohydrate). All rats consumed similar amounts of diet, and measurements were made 15 h after initiation of re-feeding. In the proximal jejunum a slight increase in aminopeptidase activity was observed after the high-protein intake. In contrast, considerable stimulation (52%) of the enzyme specific activity was obtained in the proximal ileum. This increase in ileal aminopeptidase activity was more prominent in the mature cells of the upper villus. To determine if the increase of aminopeptidase activity was due to an increased amount of enzyme protein, rocket immunoelectrophoresis was performed with detergent-solubilized brush-border protein from ileum on agarose gels containing anti-(rat brush-border) antiserum. When the same amount of enzyme activity was loaded on the gels, the peaks of immunoprecipitate for aminopeptidase were similar for animals fed on a standard or a high-protein diet. When the same amount of protein was loaded, the peak of immunoprecipitate for aminopeptidase was higher (81%) after a high-protein diet. These results showed that the high protein intake evoked an increase in aminopeptidase activity, with a concomitant increase in the amount of immunoreactive protein.     

Novel Plant Growth Inhibitors and an Insect Antifeedant from Chrysanthemum coronarium (Japanese Name: Shungiku)

The effect of overnight fasting on the dietary protein-dependent change in the fatty acid composition of tissue lipids was studied in rats fed with casein or soybean protein (20%) diets containing 5 or 2% corn oil. The activity of the Δ6-desaturase of liver microsomes, a key enzyme of linoleate metabolism to arachidonate, was depressed significantly by overnight fasting, and the protein effect disappeared, irrespective of the level of dietary fat. The proportion of linoleate in liver phosphatidylcholine was decreased, whereas that of arachidonate was increased after overnight fasting in rats fed with a low fat diet, resulting in an elevation of the linoleate desaturation index. Although the effect of fasting became obscure on a high fat diet, the protein effects were maintained even after fasting. A similar trend was also observed in various lipid fractions. Thus, the effect of dietary protein on the polyunsaturated fatty acid profile was not modulated by overnight fasting, particularly when a minimal amount of linoleic acid was supplied.     

Chronologic studies of the effects of a hypoproteinic diet followed by an equilibrated diet on delta-6 and delta-5 desaturations of linoleic acid in liver microsomes in the rat

A low protein diet affects amounts of linoleic and arachidonic acids in hepatic microsomal phospholipids of growing rats. Are the changes related to modifications in microsomal delta 6- and delta 5- linoleic acid desaturase activities? Two groups of Wistar rats weighing 80 +/- 5 g at the beginning of the experiment were used: Control group (T) was fed on a 16% gluten + 4% casein diet for 53 days; Experimental group (E) was fed on a 4% gluten + 1% casein diet for 26 days (MP) then Control diet for 27 days (RE). After 2, 14 and 26 days of MP and 2, 15 and 27 days of RE, rats of each group were sacrificed. Protein and water contents of liver, quantitative fatty acid, composition of total lipids in liver and hepatic microsomes were determined. delta 6- and delta 5- linoleic acid desaturase activities were estimated from incubation of liver microsomes with [1-14C] C 18: 2 n-6 or [2(14)C] C 20: 3 n-6 respectively. The low protein diet stops practically ponderal growth. The fatty-acid compositions of microsomal total lipids of E rats were affected in comparison with values of T rats. These modifications persist after 27 days of RE. The C 20: 4 n-6/C 18: 2 n-6 ratio in microsomal total lipids was slightly different between T and E rats but increased strongly during refeeding. Same modifications take place in the fatty-acid composition of hepatic total lipids. After two days of MP, delta 6- and delta 5- desaturase activities were depressed, phenomenon that not persist in the course of MP. These enzyme activities increase to higher values than those of the T after two days of RE.     

Molecular cloning of DNA complementary to mRNA of rat liver serine dehydratase

A cDNA clone containing sequences complementary to the mRNA cording for rat hepatic serine dehydratase was isolated to study the multihormonal regulation of this enzyme. Serine dehydratase mRNA was partially purified (50-fold enrichment, 8.2% of the total mRNA activity) from the liver of rats fed high protein diet by polysome immunoadsorption followed by oligo(dT)-cellulose column chromatography. This preparation was used as template for synthesis of cDNA. Double-stranded cDNA sequences were inserted into the plasmid pBR322 and cloned in Escherichia coli DH1. Of 860 transformants screened, 6 clones containing DNA complementary to serine dehydratase mRNA were identified by differential colony hybridization and hybrid-selected translation. The length of serine dehydratase mRNA was estimated to be 1,500 bases by Northern blot analysis. One cloned cDNA comprised about 1,000 base pairs, or 65% of the length of the mRNA. The amount of the mRNA was greatly increased in the liver of rats given high protein diet.     

Purification and regulation of mevalonate kinase from rat liver

Mevalonate kinase may play a key role in regulating cholesterol biosynthesis because its activity may be regulated via feedback inhibition by intermediates in the cholesterol biosynthetic pathway. To study the regulation of mevalonate kinase, the enzyme was purified to homogeneity from rat liver, and monospecific antibody against mevalonate kinase was prepared. The purified mevalonate kinase had a dimeric structure composed of identical subunits, and the Mr of the enzyme determined by gel chromatography was 86,000. Based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the subunit Mr was 39,900. The pI for mevalonate kinate was 6.2. The levels of mevalonate kinase protein and enzyme activity were determined in the livers of rats treated with either cholesterol-lowering agents (cholestyramine, pravastatin, and lovastatin) or with dietary modifications. Diets containing cholestyramine alone or cholestyramine and either pravastatin or lovastatin increased mevalonate kinase activity 3-6-fold. Mevalonate kinase activity decreased approximately 50% in rats treated with diets containing either 5% cholesterol or 5% cholesterol and 0.5% cholic acid. Fasting did not significantly change mevalonate kinase activity. The amount of mevalonate kinase protein in the liver was quantitated using immunoblots, and the changes in the levels of kinase activity induced by either drug treatment or by cholesterol feeding were correlated with similar changes in the levels of mevalonate kinase protein. Therefore, under these experimental conditions, mevalonate kinase activity in the liver was regulated principally by changes in the rates of enzyme synthesis and degradation.     

Antioxidant characterization of soy derived products in vitro and the effect of a soy diet on peripheral markers of oxidative stress in a heart disease model

This study analyzed and compared the content of isoflavones in 2 soy products, the effectiveness of isoflavones as antioxidants, in vitro, and demonstrated the antioxidant effect of a soy diet in rats with myocardial infarction (MI). Isoflavone content was analyzed in soybean hypocotyl (SH) and isolated soy protein (ISP). The quality (TAR) and quantity (TRAP) of antioxidants present in the samples was quantified. The amount of daidzin was higher in SH (9 times) and genistein in ISP (5 times). SH presented a 3-fold increase in TAR, while both products exhibited same TRAP. The rats were fed an ISP diet for 9 weeks. Animals were distributed among 6 treatment groups: (i) Sham Casein; (ii) Infarct Casein < 25%; (iii) Infarct Casein > 25%; (iv) Sham Soy; (v) Infarct Soy < 25%; and (vi) Infarct Soy > 25%. MI was induced 5 weeks after the commencement of the diets. Lipid peroxidation (LPO), antioxidant enzyme activity, and levels of nitrites/nitrates were determined in blood. Rats receiving the ISP diet demonstrated increased activity of antioxidant enzyme activity and nitrite/nitrate content. In addition, the increase in LPO seen in rats subjected to MI was significantly mitigated when the ISP diet was given. These findings suggest a nutritional approach of using a soy-based diet for the prevention of oxidative-stress-related diseases such as heart failure.     

Relative and Combined Effects of Selenium, Protein Deficiency and Ethanol on Hepatocyte Ballooning and Liver Steatosis

Oxidative damage plays a key role in alcohol-mediated liver alterations. Selenium, a potent antioxidant, is decreased in alcoholics. This study was conducted to analyse if the supplementation with selenium may alter liver changes in a murine model fed ethanol and/or a 2 % protein-containing diet, following the Lieber–DeCarli design. Adult male Sprague Dawley rats were divided into eight groups which received the Lieber–DeCarli control diet; an isocaloric, 36 % ethanol-containing diet; an isocaloric, 2 % protein-containing diet; and an isocaloric diet containing 2 % protein and 36 % ethanol diet; and other similar four groups to which selenomethionine (1 mg/kg body weight) was added. After sacrifice (5 weeks later), liver fat amount and hepatocyte areas of pericentral and periportal cells were measured, and liver and serum selenium, activity of liver glutathione peroxidase (GPX), and liver malondialdehyde were determined. Ethanol-fed rats showed increased hepatocyte areas and fat accumulation especially when ethanol was added to a 2 % protein diet. Selenium caused a decrease in hepatocyte ballooning and liver fat amount, but an increase in GPX activity, and a marked increase in serum and liver selenium. The present study demonstrates that selenium, added to the diet of rats in the form of seleniomethionine, prevents the appearance of early signs of ethanol-mediated liver injury under the conditions of the Lieber–DeCarli experimental design.     

Role of Glucose-6-phosphatase in Hepatic and Renal Gluconeogenesis

Comparison of the effects of a high fat and high protein diet on the capacity for glucose formation from pyruvate and glycerol was investigated in vivo and in vitro. Ratios of radioactivity incorporated from either pyruvate-3-¹⁴C or glycerol-l-¹⁴C into blood glucose to those into expired CO₂ were higher in both groups fed the high fat and the high protein diet than those in a group fed a high carbohydrate diet. Gluconeogenesis from pyruvate and glycerol by liver slices were both increased significantly in rats fed the high fat diet, while feeding the high protein diet caused increase of renal gluconeogenesis from pyruvate and glycerol. The activities of hepatic and renal glucose-6-phosphatase(s) were changed in a similar fashion to changes in hepatic and renal gluconeogenesis, respectively.

In addition, the response of the activity of hepatic glucose-6-phosphatase with high dietary fat was more rapid than that of the activity of renal glucose-6-phosphatase with high dietary protein. Furthermore, the intraperitoneal injection of actinomycin-D to rats resulted in decrease of the activities of renal glucose-6-phosphatase of both groups fed the high fat and the high protein diet, but no significant change of the activity of hepatic glucose-6-phosphatase was observed among dietary groups.

These findings suggested that the increases in the overall flow of metabolites towards glucose formation by feeding the high fat and the high protein diet might be based on the action of different mechanisms which regulate the activities of glucose-6-phosphatase(s) of the liver and kidney.