Effects of portacaval diversion on lipid metabolism in rat adipose tissue

Abstract

Male rats were submitted for 3 wk either to portacaval shunt or to portacaval transposition. In both cases, sham-operated pair-fed rats served as controls. After an overnight fast, insulinemia was similar in all groups, but glucagonemia was significantly higher (by 65%) and serum glucose significantly lower (by 35%) in rats with a portacaval shunt. The lipid metabolism of epididymal adipose tissue was studied in vitro, as well as in vivo. In rats with a portacaval shunt, in vitro lipogenesis from [U-14C]glucose, [1-14C]acetate, or 3H2o was 60-80% lower than in sham-operated pair-fed controls. Twice as much in vitro basal lipolysis could be determined. In addition, in vivo lipogenesis from 3H2O was markedly decreased (6 times). By contrast, in rats with portacaval transposition, in vitro lipogenesis was higher (by 80-140%) and basal lipolysis lower (by 63%) than in pair-fed controls. Thus, even when the nutritional state was taken into consideration, the type of portal diversion was the determining factor in influencing lipid metabolism in epididymal adipose tissue.

Alteration in body composition in the portacaval anastamosis rat is mediated by increased expression of myostatin

“…The proportion of visceral fat mass was similar to that of the subcutaneous fat mass in the PCA, whereas, in the SO rats, the proportion of the subcutaneous fat mass was higher than that of the visceral fat mass. Our data are consistent with previous metabolic studies, that adipose tissue lipogenesis is reduced by 60 -80% and lipolysis increased twofold in PCA compared with pair-fed SO rats (31), and provide the mechanism for these observations. The loss of adipose tissue mass in the PCA rat was due to a combination of impaired expression of genes regulating fatty acid synthesis and increased expression of genes regulating fatty acid oxidation.…”

Composition of Free Fatty Acids and Adipose Tissue Triglycerides in Portacaval Shunted Rats

“…The decrease in food intake and body weight in our experimental conditions was similar to that reported in the studies in which the button technique was used to con struct a portacaval anastomosis [22], Other authors, using the suture method, reported a greater reduction of food intake and body weight [17,21], We chose the button tech nique, as this experimental procedure allows a rapid recovery and makes evaluation of the experimental model in steady-state condi tions possible.…”

“…In the liver, the synthesis of cholesterol, triglycerides and li poproteins is decreased [18]. In adipose tis sue the rate of both lipogenesis and lipolysis is modified [17], Plasma free fatty acids (FFA), which are known to be influenced both by the hepatic uptake and adipose tissue release [11], have been described as either elevated [21] or un modified [4] in rats submitted to portacaval shunt (PCS). It has been shown, in experi mental animals and in humans, that plasma FFA composition is modified both in a state of starvation [3] and in liver cirrhosis [11,19,23].…”

In vitro lipid metabolism in the rat pancreas I. Basal lipid metabolism

“…When compared to rat epididymal adipose tissue [10], in vitro lipogenesis from ^HjO was 30 times lower in rat pancreatic fragments, on the same wet weight basis. The magnitude of lipid metabolism in the exocrine pancréas would, however, be vastly underestimated when considering de novo lipogenesis only.…”

“…The présent report, which is the first in a séries, described experiments in which rat pancreatic fragments were incubated with ^HaO, [U-*''C]glucose, [l-'^C]acétate, [l(3)(n)-^H]glycerol, [l-"'C]palmitic acid, [l-"']linoleic acid and [l-''*C]arachidonic acid. The metabolism of thèse labeled substrates was compared with results previously obtained in our laboratory on liver slices and adipose tissue fragments [8][9][10]. The rat pancréas displayed in vitro a highly active basai lipid metabolism with characteristics distinct from those observed in the two référence tissues.…”