scholarly journals Synchronization by Food Access Modifies the Daily Variations in Expression and Activity of Liver GABA Transaminase

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Dalia De Ita-Pérez ◽  
Isabel Méndez ◽  
Olivia Vázquez-Martínez ◽  
Mónica Villalobos-Leal ◽  
Mauricio Díaz-Muñoz
Keyword(s):  
Metabolic Networks ◽  
Biological Clock ◽  
Liver Homogenate ◽  
Mitochondrial Fraction ◽  
Mrna Levels ◽  
Gaba Transaminase ◽  
Daily Variations ◽  
Circadian Timing System ◽  
Metabolic Challenge ◽  
Expression And Activity

Daytime restricted feeding (DRF) is an experimental protocol that influences the circadian timing system and underlies the expression of a biological clock known as the food entrained oscillator (FEO). Liver is the organ that reacts most rapidly to food restriction by adjusting the functional relationship between the molecular circadian clock and the metabolic networks.γ-Aminobutyric acid (GABA) is a signaling molecule in the liver, and able to modulate the cell cycle and apoptosis. This study was aimed at characterizing the expression and activity of the mostly mitochondrial enzyme GABA transaminase (GABA-T) during DRF/FEO expression. We found that DRF promotes a sustained increase of GABA-T in the liver homogenate and mitochondrial fraction throughout the entire day-night cycle. The higher amount of GABA-T promoted by DRF was not associated to changes in GABA-T mRNA or GABA-T activity. The GABA-T activity in the mitochondrial fraction even tended to decrease during the light period. We concluded that DRF influences the daily variations of GABA-T mRNA levels, stability, and catalytic activity of GABA-T. These data suggest that the liver GABAergic system responds to a metabolic challenge such as DRF and the concomitant appearance of the FEO.

Hepatocellular expression of glucose-6-phosphatase is unaltered during hepatic regeneration

1998 ◽  
Vol 275 (4) ◽  
pp. G717-G722 ◽  
Author(s):  
Wisam F. Zakko ◽  
Carl L. Berg ◽  
John L. Gollan ◽  
Richard M. Green
Keyword(s):  
Gene Expression ◽  
Enzyme Activity ◽  
Protein Expression ◽  
Partial Hepatectomy ◽  
Initial Phase ◽  
Physiological Function ◽  
Liver Homogenate ◽  
Hepatic Regeneration ◽  
Mrna Levels ◽  
Microsomal Enzyme

Gluconeogenesis and glycogenolysis are essential hepatic functions required for glucose homeostasis. During the initial phase of hepatic regeneration, the immediate-early genes (IEG) are rapidly expressed, and the IEG RL-1 encodes for glucose-6-phosphatase (G-6- Pase). G-6- Pase is a microsomal enzyme essential for gluconeogenesis and glycogenolysis. This study employs a partial-hepatectomy model to examine the expression and activity of G-6- Pase. After partial hepatectomy, rat hepatic G-6- Pase gene expression is transcriptionally regulated, and mRNA levels are increased ≈30-fold. However, in contrast to this rapid gene induction, microsomal enzyme activity is unchanged after partial hepatectomy. Western blotting demonstrates that microsomal G-6- Pase protein expression is also unchanged after partial hepatectomy, and similar results are also noted in whole liver homogenate. Thus, despite marked induction in gene expression of the IEG G-6- Pase after partial hepatectomy, protein expression and enzyme activity remain unchanged. These data indicate that, although this hepatocyte IEG is transcriptionally regulated, the physiologically important level of regulation is posttranscriptional. This highlights the importance of correlating gene expression of IEG with protein expression and physiological function.

Cloning and functional characterization of an uncoupling protein homolog in hummingbirds

2001 ◽  
Vol 5 (3) ◽  
pp. 137-145 ◽  
Author(s):  
CLAUDIA R. VIANNA ◽  
THILO HAGEN ◽  
CHEN-YU ZHANG ◽  
ERIC BACHMAN ◽  
OLIVIER BOSS ◽  
...  
Keyword(s):  
Uncoupling Protein ◽  
Expression System ◽  
Functional Characterization ◽  
Pectoral Muscle ◽  
Mitochondrial Fraction ◽  
Mrna Levels ◽  
Coding Region ◽  
Reading Frame ◽  
Rapid Amplification

The cDNA of an uncoupling protein (UCP) homolog has been cloned from the swallow-tailed hummingbird, Eupetomena macroura. The hummingbird uncoupling protein (HmUCP) cDNA was amplified from pectoral muscle (flight muscle) using RT-PCR and primers for conserved domains of various known UCP homologs. The rapid amplification of cDNA ends (RACE) method was used to complete the cloning of the 5′ and 3′ ends of the open reading frame. The HmUCP coding region contains 915 nucleotides, and the deduced protein sequence consists of 304 amino acids, being ∼72, 70, and 55% identical to human UCP3, UCP2, and UCP1, respectively. The uncoupling activity of this novel protein was characterized in yeast. In this expression system, the 12CA5-tagged HmUCP fusion protein was detected by Western blot in the enriched mitochondrial fraction. Similarly to rat UCP1, HmUCP decreased the mitochondrial membrane potential as measured in whole yeast by uptake of the fluorescent potential-sensitive dye 3′,3-dihexyloxacarbocyanine iodide. The HmUCP mRNA is primarily expressed in skeletal muscle, but high levels can also be detected in heart and liver, as assessed by Northern blot analysis. Lowering the room’s temperature to 12–14°C triggered the cycle torpor/rewarming, typical of hummingbirds. Both in the pectoral muscle and heart, HmUCP mRNA levels were 1.5- to 3.4-fold higher during torpor. In conclusion, this is the first report of an UCP homolog in birds. The data indicate that HmUCP has the potential to function as an UCP and could play a thermogenic role during rewarming.

scholarly journals 0382 Sex Differences in Sleep and Quality of Life in Healthcare Shift Workers

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A146-A147
Author(s):  
H M Lammers-van der Holst ◽  
Y Zhang ◽  
L K Barger ◽  
J C Wise ◽  
A S Murphy ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Sex Differences ◽  
Daytime Sleepiness ◽  
Biological Clock ◽  
Severity Index ◽  
Shift Workers ◽  
Sleep Complaints ◽  
Circadian Timing System ◽  
Impaired Quality

Abstract Introduction Shift work is associated with insufficient and disrupted sleep and impaired quality of life due to misalignment between the timing of internal biological clock and work/sleep schedule. There are reported sex differences in the circadian timing system, in sleep, and in reported sleep complaints, but how these impact female shift workers remains unclear. Furthermore, relatively little is known about sex differences in quality of life in shift workers. The objective of this study is to investigate sex differences in sleepiness, insomnia and quality of life in healthcare shift workers. Methods Forty women (31 ± 6.4 yo) and 70 men (31.2 ± 6.7 yo) who work at least 4 night shifts a month, completed the Shift Worker Sleep and Health Survey. This REDcap administered survey included the Epworth Sleepiness Scale (ESS), Insomnia Severity Index (ISI), and Functional Outcomes of Sleep Questionnaire (FOSQ-10). Independent samples T-tests were carried out using SAS. Results Women reported significantly higher scores on the ESS compared to men (13 ± 4 vs. 11 ± 3.4, respectively; t(108)=-2.74,P=0.007), as on the ISI (13 ± 5.2 vs. 9.8 ± 5.4; t(108)=-3.05,P=0.003), indicating greater levels of daytime sleepiness and insomnia-like symptoms in female shift workers. In addition, women scored significantly lower on the FOSQ-10 than men (13.9 ± 2.9 vs. 15.3 ± 2.5; t(108)=2.68,P=0.009), suggesting a lower functional status related to activities of daily living in female shift workers. Conclusion These preliminary analyses suggest that in this group of healthcare shift workers, women are less tolerant to irregular work hours compared to men, in terms of sleep, sleepiness and quality of life. Our future goal is to understand how sleep quality and duration, daytime sleepiness, and quality of life interact, and what role sex plays in those interactions. Support The study was supported by NIH grant R01 AG044416.

Myocardial phenotyping using isotopomer analysis of metabolic fluxes

2005 ◽  
Vol 33 (6) ◽  
pp. 1413-1417 ◽  
Author(s):  
C. Des Rosiers ◽  
J.C. Chatham
Keyword(s):  
Stable Isotopes ◽  
Metabolic Networks ◽  
Mrna Levels ◽  
The Past ◽  
Metabolic Fluxes ◽  
Powerful Approach ◽  
Isotopomer Analysis ◽  
Cardiac Energy Metabolism ◽  
Specific Complex ◽  
Cardiac Energy

Over the past 20 years, stable isotopes combined with isotopomer analysis have proven to be a powerful approach to probe the dynamics of metabolism in various biological systems, including the heart. The aim of this paper is to demonstrate how isotopomer analysis of metabolic fluxes can provide novel insights into the myocardial phenotype. Specifically, building on our past experience using NMR spectroscopy and GC–MS as applied to investigations of cardiac energy metabolism, we highlight specific complex metabolic networks that would not be predicted by classical biochemistry or by static measurements of metabolite, protein and mRNA levels.

scholarly journals Disrupted Thalamic T-Type Ca2+ Channel Expression and Function During Ethanol Exposure and Withdrawal

2011 ◽  
Vol 105 (2) ◽  
pp. 528-540 ◽  
Author(s):  
J. D. Graef ◽  
T. W. Huitt ◽  
B. K. Nordskog ◽  
J. H. Hammarback ◽  
D. W. Godwin
Keyword(s):  
Chronic Alcoholism ◽  
Ethanol Exposure ◽  
Chronic Ethanol ◽  
Network Activity ◽  
Mrna Levels ◽  
Chronic Ethanol Exposure ◽  
Daily Variations ◽  
Channel Expression ◽  
Low Threshold ◽  
And Function

Chronic ethanol exposure produces profound disruptions in both brain rhythms and diurnal behaviors. The thalamus has been identified as a neural pacemaker of both normal and abnormal rhythms with low-threshold, transient (T-type) Ca2+ channels participating in this activity. We therefore examined T-type channel gene expression and physiology in the thalamus of C57Bl/6 mice during a 4-wk schedule of chronic intermittent ethanol exposures in a vapor chamber. We found that chronic ethanol disrupts the normal daily variations of both thalamic T-type channel mRNA levels and alters thalamic T-type channel gating properties. The changes measured in channel expression and function were associated with an increase in low-threshold bursts of action potentials during acute withdrawal periods. Additionally, the observed molecular and physiological alterations in the channel properties in wild-type mice occurred in parallel with a progressive disruption in the normal daily variations in theta (4–9 Hz) power recorded in the cortical electroencephalogram. Theta rhythms remained disrupted during a subsequent week of withdrawal but were restored with the T-type channel blocker ethosuximide. Our results demonstrate that a key ion channel underlying the generation of thalamic rhythms is altered during chronic ethanol exposure and withdrawal and may be a novel target in the management of abnormal network activity due to chronic alcoholism.

Potassium deprivation upregulates expression of renal basolateral Na+-HCO3 −cotransporter (NBC-1)

2000 ◽  
Vol 279 (3) ◽  
pp. F532-F543 ◽  
Author(s):  
Hassane Amlal ◽  
Khalid Habo ◽  
Manoocher Soleimani
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Thick Ascending Limb ◽  
Mrna Levels ◽  
Time Intervals ◽  
Outer Medulla ◽  
Medullary Thick Ascending Limb ◽  
Medullary Collecting Duct ◽  
Potassium Deprivation ◽  
Expression And Activity

The purpose of the present experiments was to examine the effect of potassium deprivation on the expression of the renal basolateral Na+-HCO3 − cotransporter (NBC-1). Rats were placed on a K+-free diet for various time intervals and examined. NBC-1 mRNA levels increased by about threefold in the cortex ( P < 0.04) at 72 h of K+ deprivation and remained elevated at 21 days. NBC activity increased by ∼110% in proximal tubule suspensions, with the activity increasing from 0.091 in control to 0.205 pH/min in the K+-deprived group ( P < 0.005). The inner stripe of outer medulla and cells of medullary thick ascending limb of Henle (mTAL) showed induction of NBC-1 mRNA and activity in K+-deprived rats, with the activity in mTAL increasing from 0.010 in control to 0.133 pH/min in the K+-deprived group ( P < 0.004). K+ deprivation also increased NBC-1 mRNA levels in the renal papilla ( P < 0.02). We conclude that 1) K+ deprivation increases NBC-1 expression and activity in proximal tubule and 2) K+deprivation causes induction of NBC-1 expression and activity in mTAL tubule and inner medulla. We propose that NBC-1 likely mediates enhanced HCO3 − reabsorption in proximal tubule, mTAL, and inner medullary collecting duct in K+ deprivation and contributes to the maintenance of metabolic alkalosis in this condition.

scholarly journals Bile acids of snakes of the subfamily Viperinae and the biosynthesis of C-23-hydroxylated bile acids in liver homogenate fractions from the adder, Vipera berus (Linn.)

1976 ◽  
Vol 153 (2) ◽  
pp. 343-350 ◽  
Author(s):  
S Ikawa ◽  
A R Tammar
Keyword(s):  
Bile Acids ◽  
Microsomal Fraction ◽  
Liver Homogenate ◽  
Mitochondrial Fraction ◽  
Sodium Cholate ◽  
Vipera Berus ◽  
C 23 ◽  
Liver Homogenates ◽  
Generating System ◽  
Cholanic Acid

1. Analysis of bile salts of four snakes of the subfamily Viperinae showed that their bile acids consisted mainly of C-23-hydroxylated bile acids. 2. Incubations of 14C-labelled sodium cholate (3 α, 7 α, 12 α-trihydroxy-5 β-cholan-24-oate) and deoxycholate (3 α, 12 α-dihydroxy-5 β-cholan-24-oate) with whole and fractionated adder liver homogenates were carried out in the presence of molecular oxygen and NADPH or an NADPH-generating system. The formation of C-23-hydroxylated bile acids, namely bitocholic acid (3 α, 12 α, 23xi-trihydroxy-5 β-cholan-24-oic acid) and 3 α, 7 α, 12 α, 23 ξ-tetrahydroxy-cholanic acid (3 α, 7 α, 12 α, 23 ξ-tetrahydroxy-5 β-cholan-24-oic acid), was observed mainly in the microsomal fraction and partly in the mitochondrial fraction. 3. Biosynthetic pathways of C-23-hydroxylated bile acids are discussed.

INTRACELLULAR DISTRIBUTION OF PHOSPHOMONOESTERASES IN RAT LIVER HOMOGENATE

1954 ◽  
Vol 32 (1) ◽  
pp. 383-394 ◽  
Author(s):  
Claude Allard ◽  
Gaston de Lamirande ◽  
Hugo Faria ◽  
Antonio Cantero
Keyword(s):  
Acid Phosphatase ◽  
Rat Liver ◽  
Mouse Liver ◽  
Soluble Fraction ◽  
Liver Homogenate ◽  
Mitochondrial Fraction ◽  
Nuclear Fraction ◽  
Absolute Requirement ◽  
Rat Liver Cells ◽  
Liver Homogenates

Acid phosphatase or phosphomonoesterase II activity of rat and mouse liver homogenates, prepared in 0.25 M sucrose, was found mainly in the cytoplasmic granules. Since the small percentage of activity of the nuclear fraction activity could be explained by the presence of mitochondria (which were actually counted in this fraction) it is concluded that rat and mouse liver nuclei do not contain acid phosphatase activity.A rather broad range of acid phosphatase activity was observed in rat and mouse livers depending on the time elapsed between the preparation of homogenate and the activity determinations. However, a preincubation of the tissues or isolated fractions at 37° C. for 60 min. was sufficient to increase the activity to an optimal value, and thus eliminate variations due to the latency of this enzyme.Alkaline phosphatase or phosphomonoesterase I activity was also found to be latent in rat liver homogenates. The phenomenon was less apparent than for acid phosphatase and seemed to depend mostly on the nature of the buffer employed in the assay system.Some evidence for the presence of two forms of alkaline phosphatase in rat liver cells is presented. One form of the enzyme was found to have an absolute requirement of magnesium for activity and was present in the soluble fraction, whereas the other which was not activated by magnesium seemed firmly linked to the nuclei and microsomes and was absent in the soluble fraction. The activity in the mitochondrial fraction was small and seemed of doubtful significance.

Prostaglandin-endoperoxide H synthase-2 expression and activity increases with term labor in human chorion

1997 ◽  
Vol 272 (5) ◽  
pp. E832-E840 ◽  
Author(s):  
J. E. Mijovic ◽  
T. Zakar ◽  
T. K. Nairn ◽  
D. M. Olson
Keyword(s):  
Specific Activity ◽  
Mrna Levels ◽  
Concerted Mechanism ◽  
Prostaglandin Endoperoxide ◽  
Endoperoxide H Synthase ◽  
Labor Onset ◽  
Selective Increase ◽  
Term Labor ◽  
Expression And Activity

We investigated the changes in prostaglandin-endoperoxide H synthase (PGHS) specific activity and the levels and distribution of PGHS-1 and PGHS-2 mRNA in chorion collected at term before the onset of labor (CS) and after term labor and delivery (SL). PGHS specific activity and PGHS-2 mRNA abundance were higher in chorion collected after SL compared with that obtained at CS (P < 0.001); there was no difference in the levels of PGHS-1 mRNA between CS and SI, tissues. The increase in PGHS specific activity at SL was significantly correlated with PGHS-2 mRNA expression (P < 0.05) but not with PGHS-1 mRNA levels. In situ hybridization indicated that the pervasiveness of staining for PGHS-1 mRNA throughout full-thickness membranes did not change with labor onset; however, a greater number of cells expressed PGHS-2 in SL tissues. Our results demonstrate a selective increase in PGHS-2 expression and activity in chorion trophoblasts and mesenchymal cells with term labor onset. These observations are similar to those concerning amnion and imply that a concerted mechanism may exist in the fetal membranes to induce PGHS-2 expression at labor.

scholarly journals Dexamethasone increases expression and activity of multidrug resistance transporters at the rat blood-brain barrier

2008 ◽  
Vol 295 (2) ◽  
pp. C440-C450 ◽  
Author(s):  
Vishal S. Narang ◽  
Charles Fraga ◽  
Narendra Kumar ◽  
Jun Shen ◽  
Stacy Throm ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Brain Tumors ◽  
Blood Brain Barrier ◽  
Brain Barrier ◽  
Mrna Levels ◽  
Cancer Resistance ◽  
Blood Brain ◽  
Multidrug Resistance Transporters ◽  
Dose Dependent ◽  
Expression And Activity

Brain edema is an important factor leading to morbidity and mortality associated with primary brain tumors. Dexamethasone, a synthetic glucocorticoid, is routinely prescribed with antineoplastic agents to alleviate pain associated with chemotherapy and reduce intracranial pressure. We investigated whether dexamethasone treatment increased the expression and activity of multidrug resistance (MDR) transporters at the blood-brain barrier. Treatment of primary rat brain microvascular endothelial cells with submicromolar concentrations of dexamethasone induced significantly higher levels of drug efflux transporters such as breast cancer resistance protein (abcg2), P-glycoprotein (P-gp; abcb1a/abcb1b), and MDR protein 2 (Mrp2; abcc2) as indicted by protein and mRNA levels as well as by functional activity. The effect of dexamethasone on transporter function was significant within 6 h of treatment, was dose dependent, and was reversible. Dexamethasone-induced upregulation of Bcrp and P-gp expression and function was partially abrogated by the glucocorticoid receptor (GR) antagonist RU486. In contrast, RU486 had no effect on the dexamethasone-induced upregulation of Mrp2, suggesting a GR-independent regulation of Mrp2, and a GR-dependent regulation of P-gp and Bcrp. In addition to the dexamethasone-induced upregulation of MDR transporters, we measured a dose-dependent and reversible increase in the expression of the nuclear transcription factor pregnane xenobiotic receptor (PXR). Administering dexamethasone to rats caused increased expression of PXR in brain microvessels within 24 h. These results suggest that adjuvant therapy with corticosteroids such as dexamethasone in the treatment of brain tumors may increase the expression of MDR transporters at the blood-brain barrier through pathways involving GR and PXR.

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