scholarly journals Hormonally produced changes in caeruloplasmin synthesis and secretion in primary cultured rat hepatocytes. Relationship to hepatic copper metabolism

1983 ◽  
Vol 212 (2) ◽  
pp. 297-304 ◽  
Author(s):  
A L Weiner ◽  
R J Cousins
Keyword(s):  
Culture Medium ◽  
Cultured Cells ◽  
Primary Cultures ◽  
Copper Metabolism ◽  
Rat Hepatocytes ◽  
Serum Copper ◽  
Copper Accumulation ◽  
Glucocorticoid Treatment ◽  
Hepatic Copper ◽  
Adrenergic Blocker

Hormonally produced changes in the synthesis and secretion of the serum copper-containing protein caeruloplasmin were studied in primary cultures of rat liver parenchymal cells isolated by the collagenase-perfusion technique. A rabbit antibody directed against rat caeruloplasmin was used to immunoprecipitate labelled caeruloplasmin. Isolated liver cells synthesized and secreted caeruloplasmin over a period of 3 days. Synthesis and secretion of this protein was enhanced when cells were treated with dexamethasone. The accumulation of copper was also moderately enhanced with glucocorticoid treatment. Inclusion of adrenaline in the culture medium resulted in elevated incorporation of copper into newly synthesized caeruloplasmin as well as an increase in 64Cu-labelled caeruloplasmin in the culture medium. However, adrenaline did not seem to increase the secretion of 3H-labelled protein, despite the elevation in secreted 64Cu-caeruloplasmin. This may be due to a large increase in the intracellular pool of 64Cu caused by enhanced accumulation of this metal when adrenaline is included in the incubation medium. Enhanced copper accumulation was also seen when cells were treated with glucagon. Adrenaline-stimulated accumulation of 64Cu could be inhibited by including phenoxybenzamine, an alpha-adrenergic blocker, in the culture medium. Elevation of extracellular copper caused enhancement in the detection of labelled caeruloplasmin in the medium of cultured cells, probably owing to the ability of this metal to stabilize the protein.

Induction and regulation of connexin26 by glucagon in primary cultures of adult rat hepatocytes

1995 ◽  
Vol 108 (8) ◽  
pp. 2771-2780 ◽  
Author(s):  
T. Kojima ◽  
T. Mitaka ◽  
Y. Shibata ◽  
Y. Mochizuki
Keyword(s):  
Culture Medium ◽  
Primary Cultures ◽  
Minor Component ◽  
Rat Hepatocytes ◽  
Primary Hepatocytes ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Epidermal Growth ◽  
A Minor ◽  
Junction Proteins

In the adult rat hepatocyte, the gap junction proteins consist of a major component, connexin32 (Cx32) and a minor component, connexin26 (Cx26). Although we recently reported our success in inducing and maintaining Cx32 in adult rat hepatocytes cultured in serum-free L-15 medium supplemented with epidermal growth factor and 2% dimethyl sulfoxide, it was very difficult to induce Cx26 in the primary hepatocytes. In the present study, we found that the addition of 10(−7) M glucagon into the culture medium could dramatically induce Cx26 mRNA and protein. Although the expression of Cx32 mRNA was also influenced by glucagon, the increase of the expression was small. Immunocytochemically, Cx26-positive spots were observed between most adjacent cells and were co-localized with the Cx32-positive spots. We also examined whether 0.5 mM dibutyl cyclic AMP could induce expression of Cx26 in the cells. The effect of dexamethasone on the expression of Cx26 mRNA compared to that of Cx32 mRNA was examined. For the induction and maintenance of Cx26 mRNA, more than 10(−7) M dexamethasone was necessary in this culture. These results suggest that expression of Cx26 in hepatocytes may be regulated by the concentrations of glucagon and glucocorticoid hormones.

scholarly journals Copper Ionophores as Novel Antiobesity Therapeutics

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 4957
Author(s):  
Peter M. Meggyesy ◽  
Shashank Masaldan ◽  
Sharnel A. S. Clatworthy ◽  
Irene Volitakis ◽  
Daniel J. Eyckens ◽  
...  
Keyword(s):  
Body Weight ◽  
High Fat Diet ◽  
Inductively Coupled Plasma ◽  
Copper Metabolism ◽  
Serum Copper ◽  
High Fat ◽  
Oral Gavage ◽  
Serum Ceruloplasmin ◽  
Hepatic Copper ◽  
Serum Aminotransferases

The therapeutic utility of the copper ionophore disulfiram was investigated in a diet-induced obesity mouse model (C57BL/6J background), both through administration in feed (0.05 to 1% (w/w)) and via oral gavage (150 mg/kg) for up to eight weeks. Mice were monitored for body weight, fat deposition (perigonadal fat pads), metabolic changes (e.g., glucose dyshomeostasis) and pathologies (e.g., hepatic steatosis, hyperglycaemia and hypertriglyceridemia) associated with a high-fat diet. Metal-related pharmacological effects across major organs and serums were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Disulfiram treatments (all modes) augmented hepatic copper in mice, markedly moderated body weight and abolished the deleterious systemic changes associated with a high-fat diet. Likewise, another chemically distinct copper ionophore H2(gtsm), administered daily (oral gavage), also augmented hepatic copper and moderated mouse body weight. Postmortem histological examinations of the liver and other major organs, together with serum aminotransferases, supported the reported therapeutic safety of disulfiram. Disulfiram specifically altered systemic copper in mice and altered hepatic copper metabolism, perturbing the incorporation of copper into ceruloplasmin (holo-ceruloplasmin biosynthesis) and subsequently reducing serum copper concentrations. Serum ceruloplasmin represents a biomarker for disulfiram activity. Our results establish copper ionophores as a potential class of antiobesity agents.

Effect of tri-iodothyronine on protein turnover in rat hepatocyte primary cultures

1987 ◽  
Vol 113 (2) ◽  
pp. 173-177 ◽  
Author(s):  
G. Gallo ◽  
A. Voci ◽  
P. E. Schwarze ◽  
E. Fugassa
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Culture Medium ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Cellular Proteins ◽  
Cultured Hepatocytes ◽  
Rat Hepatocyte ◽  
Cells Cultured ◽  
Stimulation Of

ABSTRACT The effect of tri-iodothyronine (T3) on protein turnover was studied using primary cultures of rat hepatocytes. Protein synthesis was significantly stimulated in cells cultured for 6 days in the presence of T3 (1 μmol/l). Protein secretion into the culture medium was not affected by the hormone. Breakdown of long-lived proteins, the bulk of cellular proteins which are preferentially degraded through the autophagic lysosomal pathway, was significantly stimulated by the hormone. It is concluded that T3 elicits a general stimulation of protein turnover in cultured hepatocytes. J. Endocr. (1987) 113, 173–177

scholarly journals Microinjection of ADP-ribosylated actin inhibits actin synthesis in hepatocyte-hepatoma hybrid cells

1996 ◽  
Vol 319 (3) ◽  
pp. 843-849 ◽  
Author(s):  
Karl H. REUNER ◽  
Anke van der DOES ◽  
Petra DUNKER ◽  
Ingo JUST ◽  
Klaus AKTORIES ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Culture Medium ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Hybrid Cells ◽  
Filamentous Actin ◽  
Clostridium Botulinum C2 Toxin ◽  
Actin Mrna ◽  
Immortalized Hepatocytes ◽  
C2 Toxin

Treatment of hepatocyte-hepatoma hybrid cells with Clostridium botulinum C2 toxin led to a 167% increase in monomeric globular actin (G-actin) and to a 57% decrease in filamentous actin (F-actin) within 2 h. Simultaneously, the level of actin mRNA was specifically decreased to 49% and actin synthesis was significantly diminished. In contrast, treatment of hybrid cells with phalloidin led to a decrease in G-actin to 55% and to a reciprocal increase in actin mRNA to 244% and an increase in actin synthesis. These alterations of actin synthesis depending on the G-actin/F-actin ratio corresponded to the autoregulation of actin synthesis observed in primary cultures of rat hepatocytes. Microinjection of C2 toxin or of phalloidin into hepatocyte-hepatoma hybrid cells had the same effects on actin synthesis as incubation with either toxin in the culture medium. Microinjection of non-polymerizable ADP-ribosylated G-actin into hepatocyte-hepatoma hybrid cells specifically decreased the incorporation of [35S]methionine into newly synthesized actin within 1 h. This decrease continued for at least 19 h. Microinjection of ADP-ribosylated actin led to rounding of cells and obvious disaggregation of actin filaments, which might be due to capping of actin filaments by the ADP-ribosylated actin. Because stabilization of actin filaments by phalloidin before microinjection of ADP-ribosylated actin also resulted in decreased actin synthesis, the concentration of monomeric G-actin seems to be responsible for the regulation of actin synthesis in hepatocyte-hepatoma hybrid cells, which can be regarded as immortalized hepatocytes.

scholarly journals Retinoid metabolism in cultured human retinal pigment epithelium

1988 ◽  
Vol 250 (2) ◽  
pp. 459-465 ◽  
Author(s):  
S R Das ◽  
P Gouras
Keyword(s):  
Fatty Acid ◽  
Culture Medium ◽  
Cultured Cells ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Primary Cultures ◽  
Retinyl Palmitate ◽  
Lipid Binding ◽  
Retinoid Metabolism ◽  
Hydrolysis Of

Uptake, esterification and release of all-trans-retinol in primary cultures of human retinal epithelium were studied. Cultured cells were supplemented with 3H-labelled 11,12-all-trans-retinol, using fatty-acid-free albumin as the carrier. This led to incorporation of retinal and the formation of all-trans- and 11-cis-retinyl palmitate. The metabolism of the all-trans ester was monitored in a medium containing various concentrations of foetal-bovine serum (FBS). In 20% (v/v) FBS, the ester was hydrolysed, and all-trans-retinol was released into the culture medium. In the absence of FBS, little ester was hydrolysed and no retinol was found in the medium. Dialysed or heat-inactivated FBS or fatty-acid-free albumin was as effective as FBS in provoking ester hydrolysis and retinol release. The concentration-dependency of this effect on FBS was matched by the corresponding concentrations of albumin alone. A linear relationship was also found between interphotoreceptor retinoid-binding protein and retinoid release. Haemoglobin, which does not bind retinoids, is ineffective in this capacity. It is concluded that lipid-binding substances, mainly albumin, in FBS act as acceptors for retinol and drain the cultured cells of this molecule. The release of the retinol is coupled to the hydrolysis of retinyl esters in the cell, so that there is little or no net hydrolysis of ester if there is no acceptor for retinol in the culture medium. This effect explains why cultured human retinal epithelial cells are depleted of their stores of retinoids when maintained in medium supplemented with FBS.

Ethanol metabolism and inhibition of nucleoside uptake lead to increased extracellular adenosine in hepatocytes

1992 ◽  
Vol 262 (5) ◽  
pp. C1175-C1180 ◽  
Author(s):  
L. E. Nagy
Keyword(s):  
Cultured Cells ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Ethanol Metabolism ◽  
Nucleoside Transporter ◽  
Extracellular Adenosine ◽  
Mediated Effects ◽  
Adenosine Uptake ◽  
Nucleoside Uptake ◽  
Acute And Chronic Effects

Recent evidence suggests that adenosine mediates many of the acute and chronic effects of ethanol in both cultured cells and whole animals. These adenosine-mediated effects of ethanol result from ethanol-induced increases in extracellular adenosine. Acute exposure of primary cultures of rat hepatocytes to 12.5-200 mM ethanol increased extracellular adenosine concentrations by 20-35%. Pretreatment of hepatocytes with 100 microM 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, completely blocked ethanol-induced increases in extracellular adenosine at 12.5 and 25 mM ethanol. However, even in the presence of 4-methylpyrazole, ethanol at concentrations greater than 50 mM still increased extracellular adenosine concentrations. This increase appears to be due to ethanol inhibition of adenosine uptake via the nucleoside transporter (50% inhibitory concentration, 28 mM). After chronic treatment with 100 mM ethanol for 48 h, acute challenge with ethanol no longer inhibited adenosine uptake, i.e., the nucleoside transporter had become tolerant to ethanol. Moreover, in these chronically treated cells, ethanol-induced increases in extracellular adenosine were completely blocked by treatment with 4-methylpyrazole at all concentrations of ethanol. Taken together, these results suggest that increased extracellular adenosine in hepatocytes is dependent on both ethanol oxidation and inhibition of adenosine uptake via the nucleoside transporter.

scholarly journals Glucagon and ammonia influence the long-term regulation of phosphate-dependent glutaminase activity in primary cultures of rat hepatocytes

1991 ◽  
Vol 274 (1) ◽  
pp. 103-108 ◽  
Author(s):  
J D McGivan ◽  
K Boon ◽  
F A Doyle
Keyword(s):  
Culture Medium ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Extracellular Medium ◽  
High Concentrations ◽  
Continuous Presence ◽  
Protein Free Diet ◽  
Glutaminase Activity

1. Glutaminase activity was measured in primary cultures of hepatocytes. 2. Enzyme activity decreased markedly after 24-40 h in culture, and this loss of activity was accompanied by loss of enzyme protein. 3. The loss of activity was delayed by high concentrations of glutamine, and was abolished by the continuous presence of NH4Cl in the culture medium. 4. In cells from rats fed on high-carbohydrate protein-free diet, glutaminase activity was increased by glucagon, but not by dexamethasone. This induction was observed only in the continuous presence of NH3 or high concentrations of glutamine. 5. It is concluded that NH3 and glutamine are essential for the stabilization and induction of glutaminase activity in hepatocytes. The inactivation of glutaminase in hepatocytes and in vivo under certain conditions may be due to lack of NH3 in the extracellular medium.

scholarly journals Wilson’s Disease Presenting in Late Adult Life

2021 ◽  
pp. 142-146
Author(s):  
Wafa AlDhaleei ◽  
Maryam AlAhmad ◽  
Ibrahim Alhosani
Keyword(s):  
Wilson’S Disease ◽  
Adult Life ◽  
Copper Metabolism ◽  
Wilson's Disease ◽  
Serum Copper ◽  
Hepatic Copper ◽  
Urinary Copper ◽  
Clinical Presentations ◽  
Function Impairment ◽  
Diagnostic Management

Wilson’s disease (WD) is an autosomal recessive disease affecting the copper metabolism resulting in various clinical presentations. Diagnosis includes the presence of low serum copper and ceruloplasmin concentrations, increased urinary copper excretion, and/or increased hepatic copper concentrations. Yet, genetic testing remains diagnostic. Management includes copper chelating agents and liver transplant in advance cases. We report a case of WD presenting with liver function impairment in late adult life and started on treatment. Therefore, early diagnosis and treatment of WD can prevent related complications.

scholarly journals Copper Supplementation, A Challenge in Cattle

Animals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1890
Author(s):  
Marta López-Alonso ◽  
Marta Miranda
Keyword(s):  
Copper Deficiency ◽  
Copper Toxicity ◽  
Copper Metabolism ◽  
Copper Accumulation ◽  
Hepatic Copper ◽  
Copper Status ◽  
Large Numbers ◽  
Copper Supplementation ◽  
Key Points ◽  
Copper Storage

Ensuring adequate copper supplementation in ruminants is a challenging task due to the complexity of copper metabolism in these animals. The three-way interaction between copper, molybdenum and sulphur (Cu-Mo-S) in the rumen makes ruminants, particularly cattle, very susceptible to suffering from secondary copper deficiency. Paradoxically, excessive copper storage in the liver to prevent deficiency becomes a hazard when ruminants are fed copper-supplemented diets even slightly above requirements. While cattle were traditionally thought to be relatively tolerant of copper accumulation, and reports of copper poisoning were until recently somewhat rare, in recent years an increased number of episodes/outbreaks of copper toxicity in cattle, particularly in dairy cattle, have been reported worldwide. The growing number of lethal cases reported seems to indicate that copper intoxication is spreading silently in dairy herds, urging the development of strategies to monitor herd copper status and improve farmers’ awareness of copper toxicity. In fact, monitoring studies carried out on numerous samples collected from culled animals in slaughterhouses and/or diagnostic laboratories have demonstrated that large numbers of animals have hepatic copper concentrations well above adequate levels in many different countries. These trends are undoubtedly due to copper supplementation aimed at preventing copper deficiency, as dietary copper intake from pasture alone is unlikely to cause such high levels of accumulation in liver tissue. The reasons behind the copper overfeeding in cattle are related both to a poor understanding of copper metabolism and the theory of “if adding a little produces a response, then adding a lot will produce a better response”. Contrary to most trace elements, copper in ruminants has narrow margins of safety, which must also be formulated considering the concentrations of copper antagonists in the diet. This review paper aims to provide nutritionists/veterinary practitioners with the key points about copper metabolism in cattle to guarantee an adequate copper supply while preventing excessive hepatic copper loading, which requires à la carte copper supplementation for each herd.

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