Studies on the Metabolic Effects Induced in the Rat by a High-Fat Diet. Control of Glucose Metabolism in Adipose Tissue of Fed and Fasted Rats

Tung

BMC Complement Altern Med

et al. 2016

BackgroundCocoa, coffee, green tea and garcinia contain large amounts of polyphenols. Polyphenols are well-known phytochemicals and found in plants, and have modulated physiological and molecular pathways that are involved in energy metabolism, adiposity, and obesity.MethodsTo evaluate the obesity-lowering effect of a combined extract (comprising cocoa, coffee, green tea and garcinia; CCGG) in high-energy diet (HED)-induced obese rats. Male Sprague Dawley rats (8 weeks old) were randomly divided into four groups (n = 12 per group): normal diet with vehicle treatment (Control), and HED to receive vehicle or CCGG by oral gavage at 129, 258, or 517 mg/kg/day for 4 weeks, designated the HED, 0.5X, 1X and 1X groups, respectively.ResultsHED induced macrovesicular fat in the liver and the formation of adipose tissues, and significantly increased the levels of serum free fatty acids (FFA), triacylglycerol (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and LDL-C/HDL-C, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and ketone bodies in serum, and hepatic TG and TC levels, and decreased the levels of high density lipoprotein cholesterol (HDL-C) in serum and lipase activity in fat tissues. Treatment with CCGG could significantly decrease the levels of FFA, TG, TC, LDL-C, and LDL-C/HDL-C, AST, ALT, and ketone bodies in serum, and hepatic TG and TC contents, and increase the levels of HDL-C in serum and lipase activity in fat tissues compared to the HED group. Liver histopathology also showed that CCGG could significantly reduce the incidence of liver lesions.ConclusionThese results suggested that CCGG stimulated lipid metabolism in HED-induced obese rats, which is attributable to fat mobilization from adipose tissue.

Section: Resultsmentioning

confidence: 99%

Beneficial effects of cocoa, coffee, green tea, and garcinia complex supplement on diet induced obesity in rats

Tung

BMC Complement Altern Med

et al. 2016

“…Pilkis (1970) showed that the major source of G6P in white adipose cells is neither glycogen nor gluconeogenic precursors but blood glucose. Further, the rate of lipid synthesis is low in the white adipose tissue of starved rats (Zaragoza-Hermans, 1974). Therefore, the intracellular concentration of G6P is probably relatively high in white adipose cells from starved animals.…”

Section: Discussionmentioning

confidence: 96%

“…Glucose thus produced may be released into the blood. In starved animals, however, the greater part of blood glucose is produced in the liver from lactate and alanine derived from the skeletal muscle (Felig et al, 1970;Kusaka and Ui, 1977), and from fatty acids derived from white and brown adipose tissues (Zaragoza-Hermans, 1974;Nedergaard and Lindberg, 19821, and is from liver glycogen (Kanamura et al, 1980). The role of glucose released directly from brown adipose cells, even if present in small amounts, is possibly to elevate the glucose level, which inclined to be low in the blood of mice starved for 3 days.…”

Section: Discussionmentioning

confidence: 99%

Significance of increase in glucose 6‐phosphatase activity in brown adipose cells of cold‐exposed and starved mice

et al. 1987

Cytochemical and biochemical glucose 6-phosphatase (G6Pase) activity was examined in brown adipose tissues of normal, cold-exposed, or starved mice. In addition, G6Pase activity in white adipose tissue and hexokinase activity in brown and white adipose tissues were biochemically measured. In normal animals, the reaction product for G6Pase activity was localized in the endoplasmic reticulum and nuclear envelope of brown adipose cells. The amount of the reaction product increased in cold-exposed or starved animals. Biochemical G6Pase activity (259.7 f 48.5 ng Pi/min/mg protein) in brown adipose tissues of normal animals was higher when the value was compared with values of other organs. Biochemical G6Pase and hexokinase activities increased rapidly in brown adipose tissues of coldexposed animals, and a close relation was found between activities of the two enzymes. In brown adipose tissues of animals starved for 3 days, biochemical G6Pase activity increased, but hexokinase activity did not change. In white adipose tissues of normal, cold-exposed, or starved animals, G6Pase activity was very low, although the enzyme activity increased slightly in animals starved for 3 days. The results show that the high G6Pase activity in brown adipose cells probably relates to thermogenesis in cold-exposed animals and may be concerned with glucose release into the blood in starved animals.

“…also considerable recycling of fructose 6-phosphate t at zero time: through the pentose phosphate cycle as suggested for bovine adipose tissue from the relative rates of 14CO2 production from [6-14C]and [2-14C]-glucose (Baldwin et al, 1973). The pattern of glucose metabolism in ruminant adipose tissue thus differs markedly from that of the rat (Flatt & Ball, 1964, 3h tissue at zero Saggerson & Greenbaum, 1970;Zaragozation of pieces of Hermans, 1973, 1974). nedium resulted…”

Section: Discussionmentioning

confidence: 99%

Regulation of glycolysis and fatty acid synthesis from glucose in sheep adipose tissue

Robertson

Faulkner

Vernon

1982

Biochemical Journal

1. The following were measured in adipose-tissue pieces, obtained from 7-9 month-old sheep, before or after the tissue pieces had been maintained in tissue culture for 24 h: the rates of synthesis from glucose of fatty acids, acylglycerol glycerol, pyruvate and lactate; the rate of glucose oxidation to CO(2); the rate of glucose oxidation via the pentose phosphate pathway; the activities of hexokinase, glucose 6-phosphate dehydrogenase, phosphofructokinase, pyruvate kinase, pyruvate dehydrogenase and ATP citrate lyase; the intra- and extra-cellular water content; the concentration of various metabolites and ATP, ADP and AMP. 2. The proportion of glucose carbon converted into the various products in sheep adipose tissue differs markedly from that observed in rat adipose tissue. 3. There was a general increase in the rate of glucose utilization by the adipose-tissue pieces after maintenance in tissue culture; largest changes were seen in the rates of glycolysis and fatty acid synthesis from glucose. These increases are paralleled by an increase in pyruvate kinase activity. There was no change in the activities of the other enzymes as measured, although the net flux through all the enzymes increased. 4. Incubation of fresh adipose-tissue pieces for 2-6h led to an increase in the affinity of pyruvate kinase for phosphoenolpyruvate. 5. The rate of pyruvate production by glycolysis was greater than the activity of pyruvate dehydrogenase of the tissue. 6. The results suggest that both pyruvate kinase and pyruvate dehydrogenase have important roles in restricting the utilization of glucose carbon for fatty acid synthesis in sheep adipose tissue.