Biomedical subjects

K Y Lei

Publications and source records attributed to K Y Lei.

At least 19 recordsLinked to original sources

PubMed2002

Zinc depletion reduced Egr-1 and HNF-3beta expression and apolipoprotein A-I promoter activity in Hep G2 cells.

We examined the influence of zinc status on expression of certain transcription factors involved in regulation of apolipoprotein A-I (apoAI) expression in human hepatoblastoma Hep G2 cells. A low zinc basal medium (zinc deficient, ZD) consisting of DMEM and 10% Chelex100-treated fetal bovine serum was used to deplete cellular zinc over one passage. Cells were also cultured for one passage in medium supplemented with 0.4 (ZD0.4), 4.0 (zinc normal, ZN), 16.0 (zinc adequate, ZA), or 32.0 microM zinc (zinc supplemented, ZS). Compared with ZN cells, cellular zinc levels were 43 and 31% lower in ZD and ZD0.4 cells but 70 and 146% higher in ZA and ZS cells, respectively. Supplementation of 0.4 microM zinc significantly increased DNA contents per plate, from 65% in ZD cells to 83% in ZD0.4 cells compared with ZN cells. Addition of >4 microM zinc in medium did not further increase DNA contents. The proportion of cells in G(1)/S and S phase was about fourfold higher and threefold lower, respectively, in ZD cells compared with ZN and other groups. Nuclear Egr-1 protein was markedly decreased in ZD and ZD0.4 cells. Moreover, hepatocyte nuclear factor (HNF)-3beta was severely degraded in ZD and ZD0.4 cells. In contrast, HNF-4alpha remained stable in all groups and was not significantly lower in ZD and ZD0.4 cells. Furthermore, downregulation of trans-acting factor Egr-1 and cleavage of HNF-3beta were associated with reduction of apoAI promoter activity in zinc-deficient Hep G2 cells. Thus zinc is critical in transcriptional regulation of apoAI gene expression in hepatocytes.

Apolipoprotein A-I↗

PubMed2001

Zinc status affects p53, gadd45, and c-fos expression and caspase-3 activity in human bronchial epithelial cells.

This study was designed to examine the influence of zinc depletion and supplementation on the expression of p53 gene, target genes of p53, and caspase-3 activity in normal human bronchial epithelial (NHBE) cells. A serum-free, low-zinc medium containing 0.4 micromol/l of zinc [zinc deficient (ZD)] was used to deplete cellular zinc over one passage. In addition, cells were cultured for one passage in media containing 4.0 micromol/l of zinc [zinc normal (ZN)], which represents normal culture concentrations (Clonetics); 16 micromol/l of zinc [zinc adequate (ZA)], which represents normal human plasma zinc levels; or 32 micromol/l of zinc [zinc supplemented (ZS)], which represents the high end of plasma zinc levels attainable by oral supplementation in humans. Compared with ZN cells, cellular zinc levels were 76% lower in ZD cells but 3.5-fold and 6-fold higher in ZA and ZS cells, respectively. Abundances of p53 mRNA and nuclear p53 protein were elevated in treatment groups compared with controls (ZN). For p53 mRNA abundance, the highest increase (3-fold) was observed in ZD cells. In contrast, the highest increase (17-fold) in p53 nuclear protein levels was detected in ZS cells. Moreover, gadd45 mRNA abundance was moderately elevated in ZD and ZA cells and was not altered in ZS cells compared with ZN cells. Furthermore, the only alteration in c-fos mRNA and caspase-3 activity was the twofold increase and the 25% reduction, respectively, detected in ZS compared with ZN cells. Thus p53, gadd45, and c-fos and caspase-3 activity appeared to be modulated by cellular zinc status in NHBE cells.

Bronchi↗

PubMed2000

Expression of the p53 tumor suppressor gene is up-regulated by depletion of intracellular zinc in HepG2 cells.

Expression and activation of the p53 tumor suppressor protein are modulated by various cellular stimuli. The objective of this work was to examine the influence of zinc depletion on the expression of p53 in HepG2 cells. Two different low Zn (ZD) media, Zn-free Opti-MEM and a ZD medium containing Chelex-100 treated serum, were used to deplete cellular zinc over one passage. Cellular zinc levels of ZD cells were significantly lower than in their controls in both the Opti-MEM and Chelex studies. p53 mRNA abundance was 187% higher in ZD Opti-MEM cells and >100% higher in ZD Chelex cells compared with their respective controls. To examine whether the effects were specific to zinc depletion, a third, zinc-replenished group (ZDA) was included in the Opti-MEM study in which cells were cultured in ZD media for nearly one passage before a change was made to zinc-adequate (ZA) medium for the last 24 h. Zinc levels in the ZDA cells were significantly higher than in ZD cells, and p53 mRNA abundance was normalized to control levels. Nuclear p53 protein levels were >100% higher in the ZD Opti-MEM cells than in ZA cells. Interestingly, the ZDA Opti-MEM cells had significantly lower levels of nuclear p53 protein than both the ZA and ZD cells. These data suggest that expression of p53, a critical component in the maintenance of genomic stability, may be affected by reductions in cellular zinc.

Carcinoma, Hepatocellular↗

PubMed2000

Regulation of intestinal apolipoprotein B mRNA editing levels by a zinc-deficient diet and cDNA cloning of editing protein in hamsters.

This study was conducted to investigate the influence of dietary zinc on intestinal apoB mRNA editing in hamsters. Apolipoprotein B-48 (apoB-48) is synthesized from the same gene as apoB-100 by a post-transcriptional, site-specific cytidine deamination, a process known as apoB mRNA editing. A cDNA encoding the hamster apoB mRNA editing enzyme was obtained by reverse transcriptase-polymerase chain reaction (RT-PCR) and the deduced amino acid sequence was found to possess high amino acid sequence identity to apoB mRNA editing enzymes from several other species. Editing activity was detected in the small intestine and colon but, like humans, none was detected in the liver. Analysis by RT-PCR indicated that the small intestine possessed the highest expression of editing enzyme mRNA abundance, whereas both liver and small intestine expressed relatively high levels of apoB mRNA. The influence of dietary zinc on intestinal apoB mRNA editing levels was examined in Golden Syrian hamsters (7 wk old) assigned to one of the following three dietary treatments: Zn-adequate (ZA, 30 mg Zn/kg diet), Zn-deficient (ZD, <0. 5 mg Zn/kg diet), or Zn-replenished (ZDA, ZD hamsters receiving ZA diet for last 2 d) for 7 wk. Hamsters consuming the ZD diet had modestly but significantly lower intestinal editing activity than ZA hamsters. Intestinal editing activity in the ZDA group was not different from that of ZA hamsters. Data derived from these studies contribute to the understanding of lipoprotein metabolism in hamsters, a suitable model for the study of atherosclerosis.

Amino Acid Sequence↗

PubMed1999

Plasma apolipoprotein B-48, hepatic apolipoprotein B mRNA editing and apolipoprotein B mRNA editing catalytic subunit-1 mRNA levels are altered in zinc-deficient rats.

Apolipoprotein B (apoB) exists as two major isoforms and serves as an obligatory component of lipid-rich plasma lipoprotein particles. Apolipoprotein B mRNA editing is a zinc-dependent, site-specific cytidine deamination that determines whether the apoB-100 or apoB-48 isoform is synthesized. The objective of this work was to examine whether dietary zinc levels affect apoB mRNA editing in vivo. Adult male Sprague-Dawley rats were randomly assigned to zinc-deficient (ZD, <0.5 mg Zn/kg diet), zinc-adequate (ZA, 30 mg Zn/kg diet) or zinc-replenished (ZDA, ZD rats fed the ZA diet for last 2 d) dietary groups for 18 d. The ratio of plasma apolipoprotein B-48 (apoB-48) to total apoB was significantly lower in zinc-deficient compared with zinc-adequate rats. Primer extension analysis indicated a modest but significant reduction in hepatic apoB mRNA editing in ZD rats compared with that of the ZA group. In ZDA rats, hepatic apoB mRNA editing and the percentage of plasma apoB-48 to total apoB were not different from ZA rats. The mRNA abundance of hepatic apobec-1 (apoB mRNA editing catalytic subunit 1) was significantly lower in ZD and ZDA rats than in ZA rats. In summary, the plasma ratio of apoB-48 to total apoB protein as well as hepatic apoB mRNA editing and hepatic apobec-1 mRNA levels were reduced in rats consuming a zinc-deficient diet. These data suggest that one or more components of apoB metabolism may be influenced by dietary zinc status.

Animals↗

PubMed1999

Apolipoprotein A-I gene expression is regulated by cellular zinc status in hep G2 cells.

The influence of Zn on the expression of the apolipoprotein A-I (apoA-I) gene in Hep G2 cells was examined. Zn depletion was achieved with a low-Zn (ZD) medium prepared from Zn-free growth medium (Opti), a ZD medium containing Chelex 100-extracted fetal bovine serum (CHE), and a medium containing chelator 1, 10-phenanthroline (OP). Compared with those for their respective controls, cellular Zn levels were reduced by 55, 48, and 46% and apoA-I mRNA abundances were reduced by 20, 29, and 28% in Opti, CHE, and OP systems, respectively, after one passage in ZD media or 24 h in OP medium. To establish the specificity of Zn treatment, groups of ZD cells were treated with their respective control media for the last 24 h (ZDA) or normal cells were cultured with OP medium supplemented with Zn (OP-Zn). ZDA treatments partially normalized cellular Zn levels in the Opti system and restored or elevated apoA-I mRNA levels in the Opti or CHE system, respectively. Similarly, the OP-Zn treatment restored the cellular Zn and apoA-I mRNA levels. Furthermore, one passage of culture with Zn-supplemented media in both the Opti and CHE systems resulted in higher cellular Zn and apoA-I mRNA levels than those for controls. Most significantly, short-term high-Zn induction to normal cells markedly elevated the cellular Zn (3-fold) and apoA-I mRNA (5-fold) levels. Data derived from this study strongly suggest that the expression of apoA-I is regulated by cellular Zn status.

Apolipoprotein A-I↗

PubMed1998

Zinc deficiency decreases plasma level and hepatic mRNA abundance of apolipoprotein A-I in rats and hamsters.

The influence of Zn deficiency on the plasma level as well as the hepatic and intestinal gene expression of apolipoprotein (apo) A-I was examined in rats and hamsters. Male Sprague-Dawley rats (8 wk old) and Golden Syrian hamsters (7 wk old) were assigned to three dietary treatments: Zn adequate (ZA, 30 mg Zn/kg diet), Zn deficient (ZD, <0.5 mg Zn/kg diet), and Zn replete (ZDA, ZD animals fed the ZA diet for the last 2 days). The dietary treatments lasted for 18 days for rats or 6 wk for hamsters. For the measurement of apoA-I mRNA abundance, hamster apoA-I cDNA was cloned from the small intestine. The full-length 905-base pair cDNA shared approximately 80% similarity with the human, rat, and mouse apoA-I cDNAs. Hepatic and plasma Zn levels were reduced in ZD animals but normalized in ZDA rats and increased in ZDA hamsters compared with ZA animals. Zn deficiency reduced plasma apoA-I and hepatic apoA-I mRNA levels 13 and 38%, respectively, in ZD rats. The 2 days of Zn replenishment raised plasma apoA-I and hepatic apoA-I mRNA levels in ZDA rats by 34 and 28%, respectively, higher than ZA rats. Similarly, these levels were decreased by 18 and 25%, respectively, in ZD hamsters but normalized in ZDA hamsters compared with ZA hamsters. In contrast to the alterations of hepatic apoA-I mRNA levels, neither Zn deficiency nor subsequent Zn repletion produced alterations in the intestinal apoA-I mRNA abundance. Data from this study demonstrated that Zn deficiency specifically decreases hepatic apoA-I gene expression, which may at least be partly responsible for the reduction of plasma apoA-I levels.

Amino Acid Sequence↗

PubMed1997

Dexamethasone and interleukin-1 potently synergize to stimulate the production of granulocyte colony-stimulating factor in differentiated THP-1 cells.

The human monocytic leukemic cell line, THP-1, which differentiates toward macrophages in response to phorbol 12-myristate 13-acetate (PMA) was investigated for its ability to produce granulocyte colony-stimulating factor (G-CSF). G-CSF protein was neither produced during PMA-induced differentiation nor in response to dexamethasone (Dex) alone. However, when combined, PMA and Dex synergistically stimulated THP-1 cells to produce G-CSF. The synergistic interaction between PMA and Dex on G-CSF production appeared to be mediated through the production of interleukin-1 (IL-1) since neutralization of IL-1 activity completely inhibited G-CSF production. Further experiments demonstrated that in THP-1 cells pretreated with PMA, Dex potently synergized with IL-1 to stimulate G-CSF production.

Cell Differentiation↗

PubMed1997

Dexamethasone potently enhances phorbol ester-induced IL-1beta gene expression and nuclear factor NF-kappaB activation.

The synthetic glucocorticoid dexamethasone, an immunosuppressive and anti-inflammatory agent, was investigated for its effect on PMA-mediated expression of the inflammatory cytokine IL-1beta in the human monocytic leukemic cell line THP-1. PMA alone induced the production of low levels of IL-1beta in THP-1 cells, whereas dexamethasone alone had no effect. However, dexamethasone potently enhanced PMA-mediated IL-1beta production. Using a selective and potent inhibitor of protein kinase C, we found that synergistic interaction between PMA and dexamethasone requires protein kinase C activation. PMA has been known to activate nuclear factor NF-kappaB in THP-1 cells. Using an oligonucleotide probe corresponding to an NF-kappaB DNA-binding motif of the IL-1beta gene promoter in gel electrophoresis mobility shift assays, we demonstrated that PMA-induced NF-kappaB activation was greatly potentiated by dexamethasone. Our results indicate that glucocorticoids can be positive regulators of inflammatory cytokine gene expression during monocytic cell differentiation.

Anti-Inflammatory Agents↗

PubMed1997

Regulation of apolipoprotein A-I gene expression in Hep G2 cells depleted of Cu by cupruretic tetramine.

Studies were designed to examine the regulation of apolipoprotein (apo) A-I gene expression in Cu-depleted Hep G2 cells. The cupruretic chelator N,N'-bis(2-aminoethyl)-1,3-propanediamine 4 HCl (2,3,2-tetramine or TETA) was used to maintain a 77% reduction in cellular Cu in Hep G2 cells. After two passages of TETA treatment, the relative abundance of apoA-I mRNA was elevated 52%. In TETA-treated cells, the rate of apoA-I mRNA decay measured by an actinomycin D chase study was accelerated 108%, and the synthesis of apoA-I mRNA determined by a nuclear runoff assay was enhanced 2.5-fold in TETA-treated cells. All of those changes could be reverted toward the control values with Cu supplementation for only 2 days. In transient transfection assays, a 26.7% increase in chloramphenicol O-acetyltransferase (CAT) activity for the reporter construct -256AI-CAT was observed in the treated cells. However, the ability of apoA-I regulatory protein 1 (ARP-1) to repress the CAT activity was not affected by the depressed Cu status. In addition, gel retardation experiments demonstrated that Cu depletion enhanced the binding of hepatocyte nuclear factor 4 (HNF-4) and other undefined nuclear factors to oligonucleotides containing site A, one of three regulatory sites of the apoA-I gene promoter. Moreover, the relative abundance of HNF-4 mRNA was increased 58% in the Cu-depleted cells. Thus the observed increase in apoA-I gene transcription may be mediated mostly by an elevated level of the regulatory factor, HNF-4. In summary, the present findings established the mechanism by which a depressed cellular Cu status can enhance apoA-I mRNA production and subsequently increase apoA-I synthesis.

Apolipoprotein A-I↗

PubMed1996

Enhanced expression of hepatic genes in copper-deficient rats detected by the messenger RNA differential display method.

The influence of copper (Cu) status on hepatic gene expression was examined by using the "messenger RNA differential display" technology. This method involves the distribution of mRNA in a two-dimensional array for the rapid identification and cloning of differentially expressed genes. Livers from male Sprague-Dawley rats that had been fed a Cu-deficient (CD) diet (9.4 micromol/kg) or a Cu-adequate (CA) diet (103.9 micromol/kg) for 6 wk were used to supply cytosolic RNA. Cytosolic RNA were reverse-transcribed in the presence of anchor primers and then amplified by polymerase chain reaction with anchor and arbitrary primer sets. The amplified cDNA were then resolved by denaturing polyacrylamide gel electrophoresis. Differences in mRNA expression between the CD and CA rats were identified. DNA fragments were cloned, sequenced and used as probes for Northern blot analysis to confirm that the identified genes were differentially expressed. The analysis of cDNA sequences by computer searches against DNA and protein databases revealed that one cDNA fragment, whose mRNA abundance was enhanced 1.2-fold by copper deficiency, is novel. Four other cDNA fragments were found to have substantial homology with rat ferritin mRNA; rat fetuin mRNA; rat mitochondrial 12S and 16S rRNA, phenylalanine-, valine- and leucine-tRNA genes; rat mitochondrial genes for 16S rRNA, tRNA-leucine and tRNA-valine; and their mRNA abundance was 0.6- to 0.8-fold higher in Cu-deficient rats. Five additional cDNAs detected by this method appeared to represent novel genes because they exhibited no substantial homology to recorded gene and protein sequences deposited in DNA and protein databases. These results demonstrate the usefulness of this technology in the detection of genes which were differentially expressed as a result of the deprivation of a single nutrient, dietary copper, in this research project.

Animals↗

PubMed1996

Copper deficiency increases hepatic apolipoprotein B secretion and mRNA editing in rats.

Male weanling Sprague-Dawley rats were assigned to copper-deficient (9.0 mumol Cu/kg diet) or copper-adequate (102 mumol Cu/kg diet) dietary treatments for 6 wk. Pulse-chase studies using freshly isolated rat liver parenchymal cells demonstrated that apolipoprotein B (apoB)-48 and apoB-100 syntheses were not altered, but secretion was increased twofold in hepatocytes derived from copper-deficient rats. Both plasma apoB-48 and apoB-100 levels were increased by copper deficiency, but only the apoB-48 increase was significant. Hepatic apoB mRNA editing, expressed as a ratio of apoB-48 mRNA to apoB-48 plus apoB-100 mRNA, was significantly increased from 60.8% in copper-adequate to 70.2% in copper-deficient rats. Moreover, hepatic apoB mRNA abundance was not significantly altered by copper deficiency. Thus the increased amount of nascent apoB-48 secreted into the medium as well as the enhanced apoB mRNA editing may have contributed to the differential increase in plasma apoB-48 over apoB-100 level in copper-deficient rats.

Animals↗

PubMed1996

Copper deficiency increases total protein and apolipoprotein A-I synthesis in the rat small intestine.

This study was designed to determine whether an enhanced intestinal synthesis of apolipoprotein (apo) A-I is associated with the hyperapolipoproteinemia observed in copper-deficient rats. Male weanling Sprague-Dawley rats were assigned to two dietary treatments, Cu deficient (0.6 ppm Cu) and Cu adequate (6.0 ppm Cu) for 6 weeks. In vivo studies were then performed after rats were injected with a flooding dose of 150 microM [3H]phenylalanine (PHE, 50 microCi/ml/100 g body wt). Three rats from each treatment were sacrificed at 5, 10, 15, 30, and 60 min postinjection. The small intestine was rapidly rinsed and frozen in liquid N2. In vitro studies were performed by labeling freshly isolated 6-cm segments from duodenum, jejunum and ileum with [3H]PHE (33 microCi/ml, 49.7 Cl/mmol) in PHE-free minimum essential medium for 7 and 14 min. In vivo and in vitro intestinal samples were sonicated, solubilized in 1% Triton X-100, and centrifuged to provide the detergent soluble fraction for the isolation of nascent apo A-I and total protein. Radioactivities associated with nascent apo A-I isolated by immunoprecipitation and SDS-PAGE, and with total protein precipitated by trichloroacetic acid, were measured to determine the influence of Cu deficiency on nascent apo A-I and total protein synthesis. In the Cu-deficient small intestine, the synthesis of total protein was measured only in the duodenum and was enhanced after 1 hr for the in vivo studies. Moreover, total protein synthesis was enhanced at both 7 and 14 min of the in vitro studies for all three small intestinal segments of the Cu-deficient rats. Apo A-I synthesis was measured only at the jejunum and was also enhanced by Cu deficiency in the in vitro studies. Thus, an increase in intestinal apo A-I synthesis may contribute to the elevated plasma apo A-I level in Cu-deficient rats.

Animals↗

PubMed1995

Copper deficiency increases hepatic apolipoprotein A-I synthesis and secretion but does not alter hepatic total cellular apolipoprotein A-I mRNA abundance in rats.

This study was designed to determine whether an increase in hepatic apolipoprotein A-I (apo A-I) synthesis and mRNA abundance is responsible for the enlarged plasma apo A-I pool observed in copper-deficient rats. Weanling male Sprague-Dawley rats were divided into two dietary treatments: copper-adequate (102.2 mumol Cu/kg diet) and copper-deficient (9.0 mumol Cu/kg diet). Copper deficiency resulted in a significant increase (124%) in intravascular apo A-I pool size after 6 wk of treatment. Following intraportal injection of a flooding dose of [3H]phenylalanine, in vivo hepatic apo A-I synthesis and secretion were significantly greater in the copper-deficient animals as detected by [3H]phenylalanine incorporation into immunoprecipitable apo A-I isolated from liver homogenates and plasma using anti-rat apo A-I antibodies. Pulse-chase experiments using freshly isolated hepatocytes demonstrated that a significant increase (148%) in apo A-I secretion by hepatocytes derived from copper-deficient rats may have resulted from increased hepatic synthesis rather than altered intracellular degradation of apo A-I. Hepatic total cellular apo A-I mRNA abundance was not altered by copper deficiency when expressed per microgram of RNA. Thus, the enhanced hepatic apo A-I synthesis, observed in copper-deficient cells, may have resulted from alterations in post-transcriptional and translational processes.

Amino Acids↗

PubMed1995

Apolipoprotein A-I synthesis and secretion are increased in Hep G2 cells depleted of copper by cupruretic tetramine.

Two amine chelators, namely N,N'-bis(2-aminoethyl)-1,3-propanediamine-4 HCl (2,3,2-tetramine) and diamsar, were used at various levels to deplete copper (Cu) from cultured Hep G2 cells. For cells cultured at 0.63 mumol of Cu/L, maximal depletions were attained after 24 h of incubation with 10 mumol of either chelator/L, which resulted in an average significant depletion of 45% of cellular Cu. In addition, when cells were cultured continuously for four passages at 0.63 mumol Cu/L with 20 mumol of 2,3,2-tetramine/L, cellular Cu was significantly depleted more than 40% compared with controls. Furthermore, after two passages of 2,3,2-tetramine treatment, cells were pulsed for 10 min with [3H]leucine and chased up to 2 h. At the end of the pulse, the amount of [3H]leucine incorporated into apolipoprotein A-I was twofold greater (P < 0.05) in treated than in control cells. No difference was detected for the synthesis of apolipoprotein B and total protein. During the chase, the cellular depletion curves for apolipoprotein A-I, apolipoprotein B and total protein were not altered by 2,3,2-tetramine treatment. From 30 to 120 min of the chase, the amount of nascent apolipoprotein A-I degraded was small and not altered, but that secreted into the medium was 56% higher (P < 0.05) in the Cu-depleted than in the control cells.

Apolipoprotein A-I↗

PubMed1994

Pool size and concentration of plasma cholesterol are increased and tissue copper levels are reduced during early stages of copper deficiency in rats.

The progressive development of hypercholesterolemia, enlargement of plasma cholesterol pool size, and alteration in tissue mineral concentrations were determined during the early stages of copper deficiency. Fifty-four weanling male Sprague-Dawley rats were assigned to three dietary Cu treatments: deficient (0.6 micrograms Cu/g diet), marginal (1.6 micrograms Cu/g diet) and adequate (6.6 micrograms Cu/g diet). Six rats from each treatment were killed after 3, 5 and 7 wk of dietary treatment. After only 3 wk of treatment, significantly lower hematocrits and liver Cu concentrations, as well as enlargements of plasma volume, plasma pool size of cholesterol and triacylglycerols and relative heart weight, were evident in rats fed the Cu-deficient and Cu-marginal diets relative to those fed the Cu-adequate diet. In general, these alterations were more pronounced in rats fed the Cu-deficient diet than in rats fed the Cu-marginal diet. Thereafter, the hematocrits and plasma volumes remained relatively constant, but the liver Cu concentration progressively decreased in rats in all treatments throughout the study. In contrast, the enlargements in plasma pool size of cholesterol and triacylglycerols relative to Cu-adequate rats were greater at the end of the study for the Cu-marginal and Cu-deficient rats. Most importantly, in the Cu-marginal rats, significantly greater plasma cholesterol and triacylglycerol pool sizes were detected earlier than were differences in concentrations. Thus, the present study established plasma cholesterol and triacylglycerol pool sizes as superior indices for the early detection of alterations in lipid metabolism in Cu deficiency.

Administration, Oral↗

PubMed1994

Copper deficiency shifts energy substrate utilization from carbohydrate to fat and reduces fat mass in rats.

The influence of copper deficiency on energy metabolism and body composition was examined in rats. Weanling male Sprague-Dawley rats were assigned to two dietary treatments: copper-adequate (102.2 mumol/kg) and copper-deficient (9.0 mumol/kg). After 4 wk of treatment, rats were individually housed in metabolic cages within indirect calorimetry units for measurements of respiratory quotient to determine substrate utilization. Body composition was measured by total body electrical conductivity. Net energetic efficiency and fasting heat production were determined from regression analysis of metabolizable energy intake and energy retention (metabolizable energy intake-heat production). Rats were given free access to their respective diets for almost the entire study but were restricted to 70% of normal energy intake for 2 d to provide a range of energy intake required for the regression analysis. Energetic evaluations were determined for 12 d at normal intake and 2 d at a modest restriction (30%). Copper deficiency reduced the respiratory quotient values (0.85 to 0.80), carbohydrate utilization (7.9 to 5.2 g/d), energy retention [8.4 to -66.9 kJ/kg0.75.d)] and energy efficiency (97.8 to 87.7%). However, daily metabolizable energy intake and absolute fasting heat production were not altered. Reductions in final body weights (289 to 263 g), absolute fat mass (65.7 to 51.5 g) and proportion of body fat (22.7 to 19.6 g/100 g) were observed in copper-deficient rats compared with controls when all indirect calorimetry measurements were completed after 7 wk of treatment. Thus, copper deficiency increased utilization of fat as substrate for energy and reduced body fat mass in rats.

Adipose Tissue↗

PubMed1993

Copper deficiency increases in vivo hepatic synthesis of fatty acids, triacylglycerols, and phospholipids in rats.

This study examined the influence of dietary copper status on the in vivo hepatic fatty acid synthesis and the incorporation of nascent fatty acids into various hepatic lipid classes. Fifty weanling male Sprague-Dawley rats were assigned to two dietary treatments, copper deficient (5.4 nmol/g of diet) and copper adequate (102 nmol/g of diet). After 7 weeks of treatment, rats were injected with 0.111 MBq of [1-14C] acetate (1.85 GBq/mM)/100 g body wt through the femoral vein. Five rats from each treatment were sacrificed at 3, 6, 9, 12, and 24 min after injection. Radioactivities of nascent fatty acid samples were used to determine relative rates of fatty acid synthesis and their assembly into triacylglycerols and phospholipids. Linear increases were observed up to 12 min after injection for total hepatic fatty acid synthesis and their assembly into triacylglycerols and phospholipids for both treatments. In addition, 46% and 30% of total fatty acid synthesized were assembled into triacylglycerols and phospholipids, respectively, for both groups. Furthermore, hepatic fatty acid synthesis and assembly into triacylglycerols and phospholipids were enhanced more than 2-fold by copper deficiency when the data were expressed as per liver per 100 g body weight.

Animals↗