scholarly journals Evidence that the stimulation of lipogenesis in the mammary glands of starved lactating rats re-fed with a chow diet is dependent on continued hepatic gluconeogenesis during the absorptive period. Effects of a gluconeogenic inhibitory, mercaptopicolinic acid, in vivo

1985 ◽  
Vol 228 (3) ◽  
pp. 727-733 ◽  
Author(s):  
D H Williamson ◽  
V Ilic ◽  
R G Jones
Keyword(s):  
Mammary Gland ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Mammary Glands ◽  
Hepatic Glycogen ◽  
Chow Diet ◽  
Hepatic Gluconeogenesis ◽  
Rapid Stimulation ◽  
Stimulation Of

The rapid stimulation of lipogenesis in mammary gland that occurs on re-feeding starved lactating rats with a chow diet was decreased (60%) by injection of mercaptopicolinic acid, an inhibitor of hepatic gluconeogenesis at the phosphoenolpyruvate carboxykinase step. Mercaptopicolinate had no effect on lipogenesis in mammary glands of fed lactating rats. The inhibition of lipogenesis persisted in vitro when acini from mammary glands of re-fed rats treated with mercaptopicolinate were incubated with [1-14C]glucose. Mercaptopicolinate added in vitro had no significant effect on lipogenesis in acini from starved-re-fed lactating rats. Mercaptopicolinate prevented the deposition of glycogen and increased the rate of lipogenesis in livers of starved-re-fed lactating rats, whereas it had no significant effect on livers of fed lactating rats. Administration of intraperitoneal glucose restored the rate of mammary-gland lipogenesis in re-fed rats treated with mercaptopicolinate to the values for re-fed rats. Hepatic glycogen deposition was also restored, and the rate of hepatic lipogenesis was stimulated 5-fold. It is concluded that stimulation of mammary-gland lipogenesis on re-feeding with a chow diet after a period of starvation is in part dependent on continued hepatic gluconeogenesis during the absorptive period. Possible sources of the glucose precursors are discussed.

scholarly journals Impaired lipogenesis in mammary glands of lactating rats fed on a cafeteria diet. Reversal of inhibition of glucose metabolism in vitro by insulin

1980 ◽  
Vol 186 (3) ◽  
pp. 1005-1008 ◽  
Author(s):  
L Agius ◽  
B J Rolls ◽  
E A Rowe ◽  
D H Williamson
Keyword(s):  
Mammary Gland ◽  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Mammary Glands ◽  
High Energy ◽  
Cafeteria Diet ◽  
Chow Diet

In lactating rats fed on a cafeteria diet (chow plus palatable high-energy foods) the decreased glucose uptake and lipogenesis in vitro in acini correlated with the depressed mammary-gland lipogenesis in vivo. Insulin in vitro restored the rate of glucose uptake and its conversion to lipid to values approaching those for acini from rats fed on the chow diet alone.

scholarly journals Transcriptional repression of the gluconeogenic gene PEPCK by the orphan nuclear receptor SHP through inhibitory interaction with C/EBPα

2007 ◽  
Vol 402 (3) ◽  
pp. 567-574 ◽  
Author(s):  
Min Jung Park ◽  
Hee Jeong Kong ◽  
Hye Young Kim ◽  
Hyeong Hoe Kim ◽  
Joon Hong Kim ◽  
...  
Keyword(s):  
Nuclear Receptor ◽  
Transcriptional Repression ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Regulatory Element ◽  
Direct Interaction ◽  
Orphan Nuclear Receptor ◽  
Hepatic Gluconeogenesis ◽  
Inhibitory Interaction

SHP (short heterodimer partner) is an orphan nuclear receptor that plays an important role in regulating glucose and lipid metabolism. A variety of transcription factors are known to regulate transcription of the PEPCK (phosphoenolpyruvate carboxykinase) gene, which encodes a rate-determining enzyme in hepatic gluconeogenesis. Previous reports identified glucocorticoid receptor and Foxo1 as novel downstream targets regulating SHP inhibition [Borgius, Steffensen, Gustafsson and Treuter (2002) J. Biol. Chem. 277, 49761–49796; Yamagata, Daitoku, Shimamoto, Matsuzaki, Hirota, Ishida and Fukamizu (2004) J. Biol. Chem. 279, 23158–23165]. In the present paper, we show a new molecular mechanism of SHP-mediated inhibition of PEPCK transcription. We also show that the CRE1 (cAMP regulatory element 1; −99 to −76 bp relative to the transcription start site) of the PEPCK promoter is also required for the inhibitory regulation by SHP. SHP repressed C/EBPα (CCAAT/enhancer-binding protein α)-driven transcription of PEPCK through direct interaction with C/EBPα protein both in vitro and in vivo. The formation of an active transcriptional complex of C/EBPα and its binding to DNA was inhibited by SHP, resulting in the inhibition of PEPCK gene transcription. Taken together, these results suggest that SHP might regulate a level of hepatic gluconeogenesis driven by C/EBPα activation.

scholarly journals An in Vitro Model of Post-Exercise Hepatic Gluconeogenesis in the Gulf Toadfish Opsanus Beta

1989 ◽  
Vol 147 (1) ◽  
pp. 393-406 ◽  
Author(s):  
PATRICK J. WALSH
Keyword(s):  
Isolated Hepatocytes ◽  
Blood Parameters ◽  
Strenuous Exercise ◽  
Hepatic Gluconeogenesis ◽  
Post Exercise ◽  
Opsanus Beta ◽  
Stimulation Of ◽  
Gulf Toadfish

During strenuous exercise, fish develop substantial proton and lactate loads. Although acidosis is usually rapidly corrected during recovery (1–2 h), lactate levels often remain elevated for up to 8–12 h. The quantitative role of the liver in clearance of the lactate load during recovery from exercise in fish has received little direct examination. The purposes of this study were (1) to attempt to quantify hepatic contribution to lactate clearance, and (2) to identify factors that regulate hepatic gluconeogenesis during recovery from exercise in fish. Both in vivo and in vitro (isolated hepatocytes) approaches were used. Important blood parameters (pHe, Ccoco2, [lactate], [glucose], [epinephrine] and [norepinephrine]) were measured in the gulf toadfish (Opsanus beta Goode and Bean) during recovery from strenuous exercise, and they conformed to the general patterns for sluggish benthic species noted in earlier studies. When toadfish hepatocytes wereexposed to simulated post-exercise conditions in vitro, gluconeogenesis from lactate was stimulated by over 2.5-fold in ‘0–1 h-’ and ‘l-2h-post-exercise periods’. Variation of the extracellular parameters in controlled combinations indicated that exercise-induced changes in [glucose], [epinephrine], [norepinephrine], Pcoco2 and [HCO3−] had no significant effects on rates of gluconeogenesis.The observed stimulation of gluconeogenesis could be induced independently byeither decreased pH (which lowered Km for lactate) or increased [lactate] (bysimple hyperbolic kinetic effects), but the effects were not additive. Despite thispotentially adaptive stimulation of gluconeogenesis, I estimate, based on observedin vitro rates and in vivo estimates of lactate load, that hepatic gluconeogenesisaccounts for less than 2% of the lactate load clearance in toadfish.

334 ADENOVIRAL VECTOR-MEDIATED EXPRESSION OF RECOMBINANT HUMAN GLUCOCEREBROSIDASE IN THE MAMMARY GLAND OF RATS

2013 ◽  
Vol 25 (1) ◽  
pp. 314
Author(s):  
K. C. S. Tavares ◽  
C. Feltrin ◽  
I. S. Carneiro ◽  
A. S. Morais ◽  
C. D. Medeiros ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Mammary Glands ◽  
Santa Cruz ◽  
Cmv Promoter ◽  
Hek 293 ◽  
Hek 293 Cells ◽  
293 Cells ◽  
Control Milk

Glucocerebrosidase is a lysosomal enzyme that plays a key role in sphingolipid cleavage, an intermediate in glycolipid metabolism. A recessive mutation in the glucocerebrosidase gene leads to the accumulation of glucosylceramide in macrophages (sphingolipidosis), a lysosomal storage disease known in humans as the Gaucher disease. The enzyme replacement treatment with recombinant human glucocerebrosidase (hGCase) dramatically reduces and reverses symptoms, with the need of lifelong treatment for patients to attain a normal life. Currently, hGCase is very costly, being produced through in vitro expression in Chinese hamster ovary cells or in vivo, in plants. The aim of this study was to develop a model for the production of hGCase in the mammary gland of rats transiently transduced with recombinant adenovirus. A replication-defective adenovirus carrying hGCase was generated using the AdEasy™ adenoviral vector system (Stratagene, La Jolla, CA, USA). The hGCase cDNA (NM_001005741) was in vitro-synthesized and ligated in the XhoI site of the pAdTrack-CMV vector (pAdT-hGCase). The resulting plasmid was recombined with the pAdEasy™ vector in BJ5183 electro-competent cells. The purified pAdE-pAdT-hGCase vector was linearized and transfected into HEK-293 cells for the production of a primary viral stock. Further amplifications and the titration assay were done in HEK-293 cells, monitoring the transduction by the qualitative evaluation of green fluorescent protein (GFP) expression. Following transfection, the HEK-293 cells increasingly expressed the GFP reporter, regulated by a CMV promoter, in tandem with the hGCase cDNA, under another CMV promoter. On Day 18 of gestation, a female rat (Rattus norvegicus) was anesthetized and the 2 left caudal mammary glands were infused with 109 GTU mL–1 of the pAdE-pAdT-hGCase in PBS solution supplemented with 36 mM EGTA. The 2 right caudal mammary glands were infused only with PBS-EGTA (control milk). Milk samples collected from Days 2 through 9 post-partum were mixed with separation buffer (10 mM Tris-HCl, pH 8.0; 10 mM CaCl2) and centrifuged, with the supernatant assayed for hGCase by Western blot using a monoclonal anti-human glucocerebrosidase antibody (sc-166407, Santa Cruz Biotechnology, Santa Cruz, CA, USA). Relative quantification of the hGCase expression was done using the FluorChem FC2 system (Alpha Innotech, San Leandro, CA, USA), with hGCase band intensity being normalized against GAPDH expression. The in vivo expression assay confirmed the production of hGCase in the secreted portion of the rat milk, with a specific band between 50 to 60 kDa observed on the Western blot, and no detection of the protein in the control milk. The hGCase peak production occurred in Days 5 and 6 of lactation, with levels being 35 times greater than on Day 9. An ELISA quantification assay and an enzymatic activity assay for the recombinant hGCase are currently in development. In conclusion, the use of the rat for hGCase transient expression in the milk was proven a valid model for testing the potential use of a mammary gland expression system for the production of a functional human glucocerebrosidase protein.

scholarly journals The regulation of lipogenesis in vivo in the lactating mammary gland of the rat during the starved-refed transition. Studies wtih acarbose, a glucosidase inhibitor

1987 ◽  
Vol 242 (1) ◽  
pp. 235-243 ◽  
Author(s):  
S W Mercer ◽  
D H Williamson
Keyword(s):  
Mammary Gland ◽  
Time Course ◽  
Chow Diet ◽  
Glucosidase Inhibitor ◽  
Lactating Mammary Gland ◽  
Phosphofructokinase Activity ◽  
Time Course Study ◽  
Fructose 1,6 Bisphosphate

Depression of carbohydrate digestion by oral administration of acarbose, a glucosidase inhibitor, led to a 75% inhibition of the re-activation of lipogenesis in vivo in the mammary gland of 18 h-starved lactating rats refed with 5 g of chow diet. Rates of [1-14C]glucose incorporation in vitro into lipid and CO2 in mammary-gland acini isolated from refed animals were elevated compared with acini from starved rats, but acarbose treatment completely prevented this stimulation. Gastric intubation of glucose led to a large stimulation of lipogenesis in the mammary gland of starved lactating rats, similar to that induced by refeeding with chow diet; this was dependent on the amount of glucose given and the time elapsed between glucose administration and injection of 3H2O for the measurement of lipogenesis. The switch-on of lipogenesis in the mammary gland of starved lactating rats, by refeeding or by intubation of glucose, was associated with a decrease in the ratio of [glucose 6-phosphate]/[fructose 1,6-bisphosphate] in the gland, indicative of an increase in phosphofructokinase activity. A time-course study revealed that the ratio decreased rapidly over the first 30 min of chow refeeding, after which a large surge in lipogenesis was seen. Acarbose, given 25 min after the onset of refeeding, led to a stepwise increase in the ratio, in parallel with the observed decrease in lipogenic activity. It is concluded that the control of lipogenesis in the mammary gland is closely linked to the availability of dietary carbohydrate. An important site of regulation of lipogenesis in the gland appears to be at the level of phosphofructokinase. A possible role of insulin in the regulation of phosphofructokinase activity, and the acute modulation of insulin-sensitivity in the gland during the starved-refed transition, are discussed.

scholarly journals The role of acetyl-CoA carboxylase phosphorylation in the control of mammary gland fatty acid synthesis during the starvation and re-feeding of lactating rats

1986 ◽  
Vol 237 (1) ◽  
pp. 85-91 ◽  
Author(s):  
M R Munday ◽  
D G Hardie
Keyword(s):  
Mammary Gland ◽  
Kinetic Parameters ◽  
Protein Phosphatase ◽  
Mammary Glands ◽  
Phosphate Content ◽  
Acetyl Coa Carboxylase ◽  
Acetyl Coa ◽  
Carboxylase Activity

Activation of acetyl-CoA carboxylase during incubation of crude extracts of lactating rat mammary gland with Mg2+ and citrate can be blocked by NaF, suggesting that it represents a dephosphorylation of the enzyme. The greater extent of activation in extracts from 24 h-starved rats (200%) compared with fed controls (70%) implies that the decrease in acetyl-CoA carboxylase activity in response to 24 h starvation may involve increased phosphorylation of the enzyme. Acetyl-CoA carboxylase was purified from the mammary glands of lactating rats in the presence of protein phosphatase inhibitors by avidin-Sepharose chromatography. Starvation of the rats for 24 h increased the concentration of citrate giving half-maximal activation by 75%, and decreased the Vmax. of the purified enzyme by 73%. This was associated with an increase in the alkali-labile phosphate content from 3.3 +/- 0.2 to 4.5 +/- 0.4 mol/mol of enzyme subunit. Starvation of lactating rats for 6 h, or short-term insulin deficiency induced by streptozotocin injection, did not effect the kinetic parameters or the phosphate content of acetyl-CoA carboxylase purified from mammary glands. The effects of 24 h starvation on the kinetic parameters and phosphate content of the purified enzyme were completely reversed by re-feeding for only 2.5 h. This effect was blocked if the animals were injected with streptozotocin before re-feeding, suggesting that the increase in plasma insulin that occurs on re-feeding was responsible for the activation of the enzyme. The effects of re-feeding 24 h-starved rats on the kinetic parameters and phosphate content of acetyl-CoA carboxylase could be mimicked by treating enzyme purified from 24 h-starved rats with protein phosphatase-2A in vitro. Our results suggest that, in mammary glands of 24 h-starved lactating rats, insulin brings about a dephosphorylation of acetyl-CoA carboxylase in vivo, which may be at least partly responsible for the reactivation of mammary lipogenesis in response to re-feeding.

scholarly journals Effects of lactation on l-leucine metabolism in the rat. Studies in vivo and in vitro

1981 ◽  
Vol 194 (3) ◽  
pp. 941-947 ◽  
Author(s):  
J R Viña ◽  
D H Williamson
Keyword(s):  
Turnover Rate ◽  
Mammary Glands ◽  
Cafeteria Diet ◽  
Oxidative Decarboxylation ◽  
Chow Diet ◽  
Large Decrease ◽  
Leucine Metabolism ◽  
Major Route

1. The turnover rate of L-[1-14C]leucine was increased by 35% in lactating rats compared with virgin rats. Starvation or removal of pups (24 h) returned the value to that of the virgin rat. 2. Incorporation of L-[U-14C]leucine into lipid and protein of mammary glands of lactating rats in vivo increased 7-fold and 6-fold respectively compared with glands of virgin rats. Lactation caused no change in the incorporation of L-[U-14C]leucine into hepatic lipid and protein. 3. The production of 14CO2 from L[l-14C]leucine (in the presence of glucose) was similar in isolated acini from glands of fed (chow) and starved lactating rats. Feeding with a ‘cafeteria’ diet caused a slight decrease, and removal of pups a large decrease, in the oxidative decarboxylation of leucine. 4. Oxidation of L-[2-14C]leucine to 14CO2 was increased about 3-fold in acini from starved lactating rats or lactating rats fed on a ‘cafeteria’ diet compared with rats fed on a chow diet. Insulin decreased the formation of 14CO2 in all three situations. 5. Incorporation of L-[U-14C]- and [2-14C]-leucine into lipid was decreased in acini from starved lactating rats and lactating rats fed on a ‘cafeteria’ diet. Insulin tended to increase the conversion of [2-14C]leucine into lipid, but this was significant only in the case of the acini from ‘cafeteria’-fed rats. 6. Experiments with (-)-hydroxycitrate indicate that the major route for conversion of leucine carbon into lipid in acini is via citrate translocation from the mitochondria. 7. The physiological implications of these findings are discussed.

EFFECTS OF BROMOCRIPTINE AND OCCLUSION OF NIPPLES ON PROLACTIN RECEPTOR AND LACTOSE SYNTHETASE ACTIVITY IN THE MAMMARY GLAND OF THE LACTATING RAT

1981 ◽  
Vol 91 (2) ◽  
pp. 225-NP ◽  
Author(s):  
T. J. HAYDEN ◽  
S. V. SMITH
Keyword(s):  
Mammary Gland ◽  
Post Partum ◽  
Prolactin Receptor ◽  
Plasma Concentrations ◽  
Mammary Glands ◽  
Synthetase Activity ◽  
Plasma Prolactin ◽  
Sprague Dawley

The response of. prolactin receptor and lactose synthetase to suppression of plasma concentrations of prolactin was examined in normal and occluded (teat-sealed) mammary glands of Sprague–Dawley rats. Rats, with mammary glands unilaterally occluded, were given bromocriptine (2·5 mg/kg per 12 h) between days 5 and 8 post partum. Bromocriptine reduced plasma prolactin concentrations from 460·4±120·8 (mean ±s.e.m.) to 2·56 ± 0·89 ng/ml within 12 h whilst concentrations in control rats were 553·4± 110·25 ng/ml. Lactose synthetase activity declined rapidly, within 24 h, in occluded glands of both groups but was maintained for 24 h in normal glands of bromocriptine-treated rats and decreased thereafter. Prolactin receptors also declined significantly within 24 h in occluded glands. Desaturation of the prolactin receptor by bromocriptine treatment in vivo was compared with desaturation by exposure of membranes to MgCl2 in vitro. Both treatments enhanced prolactin binding but the increase after treatment with MgCl2 may have been partly artefactual since there was a selective loss of protein from the membranes. These results indicate that the prolactin receptor in rat mammary gland may be maintained after acute suppression of prolactin secretion.

scholarly journals Sodium Meta-Arsenite Ameliorates Hyperglycemia in Obese Diabeticdb/dbMice by Inhibition of Hepatic Gluconeogenesis

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Young-Sun Lee ◽  
Eun-Kyu Lee ◽  
Hyun-Hee Oh ◽  
Cheol Soo Choi ◽  
Sujong Kim ◽  
...  
Keyword(s):  
Body Weight ◽  
Blood Glucose ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Production ◽  
Diabetic Mouse ◽  
Hepatic Gluconeogenesis ◽  
Glucose Levels ◽  
Blood Glucose Levels

Sodium meta-arsenite (SA) is implicated in the regulation of hepatic gluconeogenesis-related genesin vitro; however, the effectsin vivohave not been studied. We investigated whether SA has antidiabetic effects in a type 2 diabetic mouse model. Diabeticdb/dbmice were orally intubated with SA (10 mg kg−1body weight/day) for 8 weeks. We examined hemoglobin A1c (HbA1c), blood glucose levels, food intake, and body weight. We performed glucose, insulin, and pyruvate tolerance tests and analyzed glucose production and the expression of gluconeogenesis-related genes in hepatocytes. We analyzed energy metabolism using a comprehensive animal metabolic monitoring system. SA-treated diabeticdb/dbmice had reduced concentrations of HbA1c and blood glucose levels. Exogenous glucose was quickly cleared in glucose tolerance tests. The mRNA expressions of genes for gluconeogenesis-related enzymes, glucose 6-phosphatase (G6Pase), and phosphoenolpyruvate carboxykinase (PEPCK) were significantly reduced in the liver of SA-treated diabeticdb/dbmice. In primary hepatocytes, SA treatment decreased glucose production and the expression of G6Pase, PEPCK, and hepatocyte nuclear factor 4 alpha (HNF-4α) mRNA. Small heterodimer partner (SHP) mRNA expression was increased in hepatocytes dependent upon the SA concentration. The expression of Sirt1 mRNA and protein was reduced, and acetylated forkhead box protein O1 (FoxO1) was induced by SA treatment in hepatocytes. In addition, SA-treated diabeticdb/dbmice showed reduced energy expenditure. Oral intubation of SA ameliorates hyperglycemia indb/dbmice by reducing hepatic gluconeogenesis through the decrease of Sirt1 expression and increase in acetylated FoxO1.

scholarly journals Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
KyeongJin Kim ◽  
Jin Ku Kang ◽  
Young Hoon Jung ◽  
Sang Bae Lee ◽  
Raffaela Rametta ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Whole Body ◽  
Acid Oxidation ◽  
Chow Diet ◽  
Peroxisome Proliferator ◽  
Obese Mice ◽  
Ph Domain ◽  
Peroxisome Proliferator Activated Receptor

AbstractIncreased adiposity confers risk for systemic insulin resistance and type 2 diabetes (T2D), but mechanisms underlying this pathogenic inter-organ crosstalk are incompletely understood. We find PHLPP2 (PH domain and leucine rich repeat protein phosphatase 2), recently identified as the Akt Ser473 phosphatase, to be increased in adipocytes from obese mice. To identify the functional consequence of increased adipocyte PHLPP2 in obese mice, we generated adipocyte-specific PHLPP2 knockout (A-PHLPP2) mice. A-PHLPP2 mice show normal adiposity and glucose metabolism when fed a normal chow diet, but reduced adiposity and improved whole-body glucose tolerance as compared to Cre- controls with high-fat diet (HFD) feeding. Notably, HFD-fed A-PHLPP2 mice show increased HSL phosphorylation, leading to increased lipolysis in vitro and in vivo. Mobilized adipocyte fatty acids are oxidized, leading to increased peroxisome proliferator-activated receptor alpha (PPARα)-dependent adiponectin secretion, which in turn increases hepatic fatty acid oxidation to ameliorate obesity-induced fatty liver. Consistently, adipose PHLPP2 expression is negatively correlated with serum adiponectin levels in obese humans. Overall, these data implicate an adipocyte PHLPP2-HSL-PPARα signaling axis to regulate systemic glucose and lipid homeostasis, and suggest that excess adipocyte PHLPP2 explains decreased adiponectin secretion and downstream metabolic consequence in obesity.

Sign in / Sign up

Export Citation Format

Share Document