Selenium and vitamin B6 cosupplementation improves dyslipidemia and fatty liver syndrome by SIRT1/SREBP-1c pathway in hyperlipidemic Sprague-Dawley rats induced by high-fat diet.

Previously, our group found that the dietary trace mineral element selenium and vitamin B6 (VitB6) alone was involved in lipid metabolism. However, the effects of selenium combined with VitB6 on hyperlipidemia and lipid metabolism have not been reported until now. We hypothesized that selenium and VitB6 cosupplementation would alleviate the hyperlipidemic and hepatic dysfunction and with minimum side effects in a Sprague-Dawley rat model of hyperlipidemia induced by a high-fat diet. Our results showed that selenium combined with VitB6 could improve dyslipidemia and displayed better in vivo hypocholesterolemic abilities at early intervention. Moreover, cosupplementation reduced atherogenic indexes (atherogenic index and atherogenic index of plasm) and the ratio of ApoB/ApoA1. The liver function index aspartate aminotransferase in serum was reduced, as was and total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol in liver. The intervention also increased the levels of ApoA1 in serum and high-density lipoprotein cholesterol of liver. In addition, the combination of selenium and VitB6 decreased liver lipid deposition and alleviated steatosis, reduced adipocyte size of white adipose tissue, increased the activities of hepatic lipase and total lipase and the hepatic 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGR) level, decreased the hepatic mRNA transcription of lipogenic and regulatory genes including Srebf1 and downstream fat synthesis-related enzymes (Acc and Fasn) and cholesterol synthesis speed limiting enzyme Hmgr, increased the mRNA abundance of Lcat and Cyp7a1, increased the protein expression of SIRT1 and PPARα, and up-regulated the protein expression of sterol regulatory element-binding protein 1c in the livers of hyperlipidemia rats. We first demonstrated that oral selenium and VitB6 cosupplementation exerted synergism in lowering blood and liver lipid profiles and antiatherosclerotic effects in hyperlipidemic rats by reducing endogenous cholesterol and lipid synthesis, enhancing the transport of cholesterol to hepatocytes and promoting fatty acid beta oxidation.

Overexpression of Human Mutant PANK2 Proteins Affects Development and Motor Behavior of Zebrafish Embryos.

Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a genetic and early-onset neurodegenerative disorder characterized by iron accumulation in the basal ganglia. It is due to mutations in Pantothenate Kinase 2 (PANK2), an enzyme that catalyzes the phosphorylation of vitamin B5, first and essential step in coenzyme A (CoA) biosynthesis. Most likely, an unbalance of the neuronal levels of this important cofactor represents the initial trigger of the neurodegenerative process, yet a complete understanding of the connection between PANK2 malfunctioning and neuronal death is lacking. Most PKAN patients carry mutations in both alleles and a loss of function mechanism is proposed to explain the pathology. When PANK2 mutants were analyzed for stability, dimerization capacity, and enzymatic activity in vitro, many of them showed properties like the wild-type form. To further explore this aspect, we overexpressed the wild-type protein, two mutant forms with reduced kinase activity and two retaining the catalytic activity in zebrafish embryos and analyzed the morpho-functional consequences. While the wild-type protein had no effects, all mutant proteins generated phenotypes that partially resembled those observed in pank2 and coasy morphants and were rescued by CoA and vitamin B5 supplementation. The overexpression of PANK2 mutant forms appears to be associated with perturbation in CoA availability, irrespective of their catalytic activity.

Effect of energy compound on skeletal muscle strain injury and regeneration in rats.

This study was designed to determine whether the supplement of energy compound could attenuate strain-induced damage to skeletal muscle in rats. Energy compound is a saline mixture of the following ingredients: ATP (10mg), Coenzyme-A (50 units), Coenzyme-Q(10) (50mg), Cytochrome C (30 mg) and Vitamin B(6) (50mg). Experimental animals were injured in right gastrocnemius muscles by a strain injury model. Energy compound groups were given energy compound 10 ml/kg body weight per day since injured, while saline groups were given saline at the same dose. And a sham operation was performed on the right hindlimb of control group. Plasma was centrifuged to measure lactate dehydrogenase (LDH), lactic acid (La) and creatine kinase (CK) on 3, 7 and 14 d post injury. Muscles were removed and fixed for histology observation and immunohistochemistry assay of desmin and vimentin. The results showed a similar tendency of plasma CK, La and LDH in saline and energy compound groups, while the lower level was found in the energy-compound group. The histological examination of muscle sections revealed a lower degree of damage in the energy compound group in which the expression levels of desmin and vimentin were higher than in the saline group. It is suggested that energy compound supplement may attenuate strain-induced muscle damage and facilitate its regeneration.

Kinetic studies on the metabolism of short-chain fatty acids and glucose by isolated rat colonocytes.

BACKGROUND/AIMS: Although the interest in colonic mucosal metabolism of short-chain fatty acids is steadily increasing, the kinetic parameters Vmax (maximum velocity) and Km (Michaelis constant) of the complete oxidation of these acids into CO2 by colonic epithelial cells have not previously been determined. METHODS: Isolated rat colonocytes were incubated in the presence of a concentration range of 14C-labeled acetate, propionate, butyrate, and glucose. Oxidation rates were obtained by quantifying the production of 14CO2. Vmax and Km were calculated by computer-fitting of the data to a Michaelis-Menten plot. RESULTS: The apparent Vmax values were similar comparing acetate, propionate, and butyrate (1.114 +/- 0.061, 0.991 +/- 0.072, and 1.007 +/- 0.070 mumol/min.g, respectively), but significantly lower for glucose (0.339 +/- 0.022 mumol/min.g). The corresponding Km values were all different and in the order of butyrate (0.184 +/- 0.017 mmol/L) < propionate (0.339 +/- 0.025 mmol/L) < acetate (0.487 +/- 0.019 mmol/L) < glucose (0.777 +/- 0.051 mmol/L). In substrate competition experiments, butyrate caused a strong noncompetitive inhibition of acetate oxidation and a mixed type of inhibition of propionate oxidation. Propionate inhibited the oxidation of acetate noncompetitively and that of butyrate competitively. Acetate only slightly inhibited the oxidation of propionate and butyrate. CONCLUSIONS: Colonic epithelial cells seem to utilize short-chain fatty acids in a preferential order of butyrate > propionate > acetate. Oxidation of propionate or acetate, however, may provide the energy needed for cellular functions if the metabolism of butyrate is impaired or the luminal supply is limited.

[The pharmacological properties of coenzyme A disulfide]. / Farmakologicheskie svoistva kofermenta A-disulfida.

Coenzyme A disulfide (CoA disulfide) was pharmacologically studied. It has been found to normalize lipid and carbohydrate metabolism when given in a dose of 2 mg/kg, i.m., in diverse liver dysfunctions. It possesses an antihypoxic action under hemic and histotoxic hypoxia. When given in small doses (80-160 micrograms/kg, i.v.), CoA disulfide depresses the function of cellular hemostasis.

Hyperbaric oxygen- and ethanol-induced infiltration of rat hepatic triglycerides and the protective action of coenzyme A.

The ethanol-induced increased synthesis of fatty acids in the liver is enhanced by hyperbaric oxygen exposure. Both lipid peroxidation and glutathione depletion are involved in these hepatic alterations. Coenzyme A can intervene in these mechanisms. The administration of CoA prevents hepatic lipid infiltration and the glutathione reduction induced in the rats by ethanol and hyperbaric oxygen exposure.

Fermentation of 1,2-propanediol with 1,2-ethanediol by some genera of Enterobacteriaceae, involving coenzyme B12-dependent diol dehydratase.

Klebsiella pneumoniae (Aerobacter aerogenes) ATCC 8724 was able to grow anaerobically on 1,2-propanediol and 1,2-ethanediol as carbon and energy sources. Whole cells of the bacterium grown anaerobically on 1,2-propanediol or on glycerol catalyzed conversion of 1,2-diols and aldehydes to the corresponding acids and alcohols. Glucose-grown cells also converted aldehydes, but not 1,2-diols, to acids and alcohols. The presence of activities of coenzyme B(12)-dependent diol dehydratase, alcohol dehydrogenase, coenzyme-A-dependent aldehyde dehydrogenase, phosphotransacetylase, and acetate kinase was demonstrated with crude extracts of 1,2-propanediol-grown cells. The dependence of the levels of these enzymes on growth substrates, together with cofactor requirements in in vitro conversion of these substrates, indicates that 1,2-diols are fermented to the corresponding acids and alcohols via aldehydes, acyl-coenzyme A, and acyl phosphates. This metabolic pathway for 1,2-diol fermentation was also suggested in some other genera of Enterobacteriaceae which were able to grow anaerobically on 1,2-propanediol. When the bacteria were cultivated in a 1,2-propanediol medium not supplemented with cobalt ion, the coenzyme B(12)-dependent conversion of 1,2-diols to aldehydes was the rate-limiting step in this fermentation. This was because the intracellular concentration of coenzyme B(12) was very low in the cells grown in cobalt-deficient medium, since the apoprotein of diol dehydratase was markedly induced in the cells grown in the 1,2-propanediol medium. Better cell yields were obtained when the bacteria were grown anaerobically on 1,2-propanediol. Evidence is presented that aerobically grown cells have a different metabolic pathway for utilizing 1,2-propanediol.

Biosynthesis of dimethyl selenide from sodium selenite in rat liver and kidney cell-free systems.

A pathway for the synthesis of dimethyl selenide from sodium selenite was studied in rat liver and kidney fractions under anaerobic conditions in the presence of GSH, a NADPH-generating system, and S-adenosylmethionine. Chromatography of liver or kidney soluble fraction on Sephadex G-75 yielded a Fraction C (30,000 molecular weight) which synthesized dimethyl selenide, but at a low rate. Addition of proteins eluting at the void volume (Fraction A) to Fraction C restored full activity. Fractionation of Fraction A on DEAE-cellulose revealed that its ability to stimulate Fraction C was associated with two fractions, one containing glutathione reductase and the other a NADPH-dependent disulfide reductase. It was concluded that Fraction C contains a methyltransferase acting on small amounts of hydrogen selenide produced non-enzymically by the reaction of selenite with GSH, and that stimulation by Fraction A results partly from the NADPH-linked formation of hydrogen selenide catalyzed by glutathione reductase present in Fraction A. Washed liver microsomal fraction incubated with selenite plus 20 mM GSH also synthesized dimethyl selenide, but addition of soluble fraction stimulated activity. A synergistic effect was obtained when liver soluble fraction was added to microsomal fraction in the presence of a physiological level of GSH (2 mM), whereas at 20 mM GSH the effect was merely additive. The microsomal component of the liver system was labile, had maximal activity around pH 7.5, and was exceedingly sensitive to NaAsO2 (93% inhibition by 10(-6) M arsenite in the presence of a 20,000-fold excess of GSH). The microsomal activity apparently results from a Se-methyltransferase, possibly a dithiol protein, that methylates hydrogen selenide produced enzymically by the soluble fraction or non-enzymically when a sufficiently high concentration of GSH is used.