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Sample records for inhibit stimulated lipolysis

  1. Biguanides and thiazolidinediones inhibit stimulated lipolysis in human adipocytes through activation of AMP-activated protein kinase.

    PubMed

    Bourron, O; Daval, M; Hainault, I; Hajduch, E; Servant, J M; Gautier, J F; Ferré, P; Foufelle, F

    2010-04-01

    In rodent adipocytes, activated AMP-activated protein kinase reduces the lipolytic rate. As the hypoglycaemic drugs metformin and thiazolidinediones activate this enzyme in rodents, we tested the hypothesis that in addition to their known actions they could have an anti-lipolytic effect in human adipocytes. Adipose tissue was obtained from individuals undergoing plastic surgery. Adipocytes were isolated and incubated with lipolytic agents (isoprenaline, atrial natriuretic peptide) and biguanides or thiazolidinediones. Lipolysis was quantified by the glycerol released in the medium. AMP-activated protein kinase activity and phosphorylation state were determined using standard procedures. In human adipocytes, isoprenaline and atrial natriuretic peptide stimulated the lipolytic rate three- to fourfold. Biguanides and thiazolidinediones activated AMP-activated protein kinase and inhibited lipolysis by 30-40%, at least in part by inhibiting hormone-sensitive lipase translocation to the lipid droplet. Inhibition of AMP-activated protein kinase by compound C precluded this inhibitory effect on lipolysis. Stimulation of lipolysis also induced an activation of AMP-activated protein kinase concomitant with a drop in ATP concentration. We show for the first time in human adipocytes that biguanides and thiazolidinediones activate AMP-activated protein kinase, thus counteracting lipolysis induced by lipolytic agents. In addition, beta-agonist- or ANP-stimulated lipolysis increases AMP-activated protein kinase activity. This is because of an increase in the AMP/ATP ratio, linked to activation of some of the released fatty acids into acyl-CoA. AMP-activated protein kinase activation could represent a physiological means of avoiding a deleterious drain of energy during lipolysis but could be used to restrain pharmacological release of fatty acids.

  2. 18{beta}-Glycyrrhetinic acid inhibits adipogenic differentiation and stimulates lipolysis

    SciTech Connect

    Moon, Myung-Hee; Jeong, Jae-Kyo; Lee, You-Jin; Seol, Jae-Won; Ahn, Dong-Choon; Kim, In-Shik; Park, Sang-Youel

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer 18{beta}-GA inhibits adipogenic differentiation in 3T3-L1 preadipocytes and stimulates lipolysis in differentiated adipocytes. Black-Right-Pointing-Pointer Anti-adipogenic effect of 18{beta}-GA is caused by down-regulation of PPAR{gamma} and inactivation of Akt signalling. Black-Right-Pointing-Pointer Lipolytic effect of 18{beta}-GA is mediated by up-regulation of HSL, ATGL and perilipin and activation of HSL. -- Abstract: 18{beta}-Glycyrrhetinic acid (18{beta}-GA) obtained from the herb liquorice has various pharmacological properties including anti-inflammatory and anti-bacterial activities. However, potential biological anti-obesity activities are unclear. In this study, novel biological activities of 18{beta}-GA in the adipogenesis of 3T3-L1 preadipocytes and in lipolysis of differentiated adipocytes were identified. Mouse 3T3-L1 cells were used as an in vitro model of adipogenesis and lipolysis, using a mixture of insulin/dexamethasone/3-isobutyl-1-methylxanthine (IBMX) to induce differentiation. The amount of lipid droplet accumulation was determined by an AdipoRed assay. The expression of several adipogenic transcription factors and enzymes was investigated using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. 18{beta}-GA dose-dependently (1-40 {mu}M) significantly decreased lipid accumulation in maturing preadipocytes. In 3T3-L1 preadipocytes, 10 {mu}M of 18{beta}-GA down-regulated the transcriptional levels of the peroxisome proliferator-activated receptor {gamma}, CCAAT/enhancer-binding protein {alpha} and adiponectin, which are markers of adipogenic differentiation via Akt phosphorylation. Also, in differentiated adipocytes, 18{beta}-GA increased the level of glycerol release and up-regulated the mRNA of hormone-sensitive lipase, adipose TG lipase and perilipin, as well as the phosphorylation of hormone-sensitive lipase at Serine 563. The results indicate that 18{beta

  3. Nitric oxide inhibits isoproterenol-stimulated adipocyte lipolysis through oxidative inactivation of the beta-agonist.

    PubMed Central

    Klatt, P; Cacho, J; Crespo, M D; Herrera, E; Ramos, P

    2000-01-01

    Nitric oxide has been implicated in the inhibition of catecholamine-stimulated lipolysis in adipose tissue by as yet unknown mechanisms. In the present study, it is shown that the nitric oxide donor, 2,2-diethyl-1-nitroso-oxyhydrazine, antagonized isoproterenol (isoprenaline)-induced lipolysis in rat adipocytes, freshly isolated from white adipose tissue, by decreasing the potency of the beta-agonist without affecting its efficacy. These data suggest that nitric oxide did not act downstream of the beta-adrenoceptor but reduced the effective concentration of isoproterenol. In support of the latter hypothesis, we found that pre-treatment of isoproterenol with nitric oxide abolished the lipolytic activity of the catecholamine. Spectroscopic data and HPLC analysis confirmed that the nitric oxide-mediated inactivation of isoproterenol was in fact because of the modification of the catecholamine through a sequence of oxidation reactions, which apparently involved the generation of an aminochrome. Similarly, aminochrome was found to be the primary product of isoproterenol oxidation by 3-morpholinosydnonimine and peroxynitrite. Finally, it was shown that nitric oxide released from cytokine-stimulated adipocytes attenuated the lipolytic effect of isoproterenol by inactivating the catecholamine. In contrast with very recent findings, which suggest that nitric oxide impairs the beta-adrenergic action of isoproterenol through intracellular mechanisms and not through a chemical reaction between NO and the catecholamine, we showed that nitric oxide was able to attenuate the pharmacological activity of isoproterenol in vitro as well as in a nitric oxide-generating cellular system through oxidation of the beta-agonist. These findings should be taken into account in both the design and interpretation of studies used to investigate the role of nitric oxide as a modulator of isoproterenol-stimulated signal transduction pathways. PMID:11023835

  4. Nitric oxide inhibits isoproterenol-stimulated adipocyte lipolysis through oxidative inactivation of the beta-agonist.

    PubMed

    Klatt, P; Cacho, J; Crespo, M D; Herrera, E; Ramos, P

    2000-10-15

    Nitric oxide has been implicated in the inhibition of catecholamine-stimulated lipolysis in adipose tissue by as yet unknown mechanisms. In the present study, it is shown that the nitric oxide donor, 2,2-diethyl-1-nitroso-oxyhydrazine, antagonized isoproterenol (isoprenaline)-induced lipolysis in rat adipocytes, freshly isolated from white adipose tissue, by decreasing the potency of the beta-agonist without affecting its efficacy. These data suggest that nitric oxide did not act downstream of the beta-adrenoceptor but reduced the effective concentration of isoproterenol. In support of the latter hypothesis, we found that pre-treatment of isoproterenol with nitric oxide abolished the lipolytic activity of the catecholamine. Spectroscopic data and HPLC analysis confirmed that the nitric oxide-mediated inactivation of isoproterenol was in fact because of the modification of the catecholamine through a sequence of oxidation reactions, which apparently involved the generation of an aminochrome. Similarly, aminochrome was found to be the primary product of isoproterenol oxidation by 3-morpholinosydnonimine and peroxynitrite. Finally, it was shown that nitric oxide released from cytokine-stimulated adipocytes attenuated the lipolytic effect of isoproterenol by inactivating the catecholamine. In contrast with very recent findings, which suggest that nitric oxide impairs the beta-adrenergic action of isoproterenol through intracellular mechanisms and not through a chemical reaction between NO and the catecholamine, we showed that nitric oxide was able to attenuate the pharmacological activity of isoproterenol in vitro as well as in a nitric oxide-generating cellular system through oxidation of the beta-agonist. These findings should be taken into account in both the design and interpretation of studies used to investigate the role of nitric oxide as a modulator of isoproterenol-stimulated signal transduction pathways.

  5. Adiponectin Inhibits Lipolysis in Mouse Adipocytes

    PubMed Central

    Qiao, Liping; Kinney, Brice; Schaack, Jerome; Shao, Jianhua

    2011-01-01

    OBJECTIVE Adiponectin is an adipocyte-derived hormone that sensitizes insulin and improves energy metabolism in tissues. This study was designed to investigate the direct regulatory effects of adiponectin on lipid metabolism in adipocytes. RESEARCH DESIGN AND METHODS Basal and hormone-stimulated lipolysis were comparatively analyzed using white adipose tissues or primary adipocytes from adiponectin gene knockout and control mice. To further study the underlying mechanisms through which adiponectin suppresses lipolysis, cultured 3T3-L1 adipocytes and adenovirus-mediated gene transduction were used. RESULTS Significantly increased lipolysis was observed in both adiponectin gene knockout mice and primary adipocytes from these mice. Hormone-stimulated glycerol release was inhibited in adiponectin-treated adipocytes. Adiponectin suppressed hormone-sensitive lipase activation without altering adipose triglyceride lipase and CGI-58 expression in adipocytes. Moreover, adiponectin reduced protein levels of the type 2 regulatory subunit RIIα of protein kinase A by reducing its protein stability. Ectopic expression of RIIα abolished the inhibitory effects of adiponectin on lipolysis in adipocytes. CONCLUSIONS This study demonstrates that adiponectin inhibits lipolysis in adipocytes and reveals a novel function of adiponectin in lipid metabolism in adipocytes. PMID:21430087

  6. Non-steroidal anti-inflammatory drugs activate NADPH oxidase in adipocytes and raise the H2O2 pool to prevent cAMP-stimulated protein kinase a activation and inhibit lipolysis

    PubMed Central

    2013-01-01

    Background Non-steroidal anti-inflammatory drugs (NSAIDs) —aspirin, naproxen, nimesulide, and piroxicam— lowered activation of type II cAMP-dependent protein kinase A (PKA-II) in isolated rat adipocytes, decreasing adrenaline- and dibutyryl cAMP (Bt2cAMP)-stimulated lipolysis. The molecular bases of insulin-like actions of NSAID were studied. Results Based on the reported inhibition of lipolysis by H2O2, catalase was successfully used to block NSAID inhibitory action on Bt2cAMP-stimulated lipolysis. NSAID, at (sub)micromolar range, induced an H2O2 burst in rat adipocyte plasma membranes and in whole adipocytes. NSAID-mediated rise of H2O2 was abrogated in adipocyte plasma membranes by: diphenyleneiodonium, an inhibitor of NADPH oxidase (NOX); the NOX4 antibody; and cytochrome c, trapping the NOX-formed superoxide. These three compounds prevented the inhibition of Bt2cAMP-stimulated lipolysis by NSAIDs. Inhibition of aquaporin-mediated H2O2 transport with AgNO3 in adipocytes allowed NOX activation but prevented the lipolysis inhibition promoted by NSAID: i.e., once synthesized, H2O2 must reach the lipolytic machinery. Since insulin inhibits adrenaline-stimulated lipolysis, the effect of aspirin on isoproterenol-stimulated lipolysis in rat adipocytes was studied. As expected, isoproterenol-mediated lipolysis was blunted by both insulin and aspirin. Conclusions NSAIDs activate NOX4 in adipocytes to produce H2O2, which impairs cAMP-dependent PKA-II activation, thus preventing isoproterenol-activated lipolysis. H2O2 signaling in adipocytes is a novel and important cyclooxygenase-independent effect of NSAID. PMID:23718778

  7. Non-steroidal anti-inflammatory drugs activate NADPH oxidase in adipocytes and raise the H2O2 pool to prevent cAMP-stimulated protein kinase a activation and inhibit lipolysis.

    PubMed

    Vázquez-Meza, Héctor; de Piña, Martha Zentella; Pardo, Juan Pablo; Riveros-Rosas, Héctor; Villalobos-Molina, Rafael; Piña, Enrique

    2013-05-30

    Non-steroidal anti-inflammatory drugs (NSAIDs) -aspirin, naproxen, nimesulide, and piroxicam- lowered activation of type II cAMP-dependent protein kinase A (PKA-II) in isolated rat adipocytes, decreasing adrenaline- and dibutyryl cAMP (Bt2cAMP)-stimulated lipolysis. The molecular bases of insulin-like actions of NSAID were studied. Based on the reported inhibition of lipolysis by H2O2, catalase was successfully used to block NSAID inhibitory action on Bt2cAMP-stimulated lipolysis. NSAID, at (sub)micromolar range, induced an H2O2 burst in rat adipocyte plasma membranes and in whole adipocytes. NSAID-mediated rise of H2O2 was abrogated in adipocyte plasma membranes by: diphenyleneiodonium, an inhibitor of NADPH oxidase (NOX); the NOX4 antibody; and cytochrome c, trapping the NOX-formed superoxide. These three compounds prevented the inhibition of Bt2cAMP-stimulated lipolysis by NSAIDs. Inhibition of aquaporin-mediated H2O2 transport with AgNO3 in adipocytes allowed NOX activation but prevented the lipolysis inhibition promoted by NSAID: i.e., once synthesized, H2O2 must reach the lipolytic machinery. Since insulin inhibits adrenaline-stimulated lipolysis, the effect of aspirin on isoproterenol-stimulated lipolysis in rat adipocytes was studied. As expected, isoproterenol-mediated lipolysis was blunted by both insulin and aspirin. NSAIDs activate NOX4 in adipocytes to produce H2O2, which impairs cAMP-dependent PKA-II activation, thus preventing isoproterenol-activated lipolysis. H2O2 signaling in adipocytes is a novel and important cyclooxygenase-independent effect of NSAID.

  8. Glycerol inhibition of ruminal lipolysis in vitro

    USDA-ARS?s Scientific Manuscript database

    Supplemental glycerol inhibits rumen lipolysis, a prerequisite for rumen biohydrogenation, which is responsible for the saturation of dietary fatty acids consumed by ruminant animals. Feeding excess glycerol, however, adversely affects dry matter digestibility. To more clearly define the effect of...

  9. Bacterial peptidoglycan stimulates adipocyte lipolysis via NOD1.

    PubMed

    Chi, Wendy; Dao, Dyda; Lau, Trevor C; Henriksbo, Brandyn D; Cavallari, Joseph F; Foley, Kevin P; Schertzer, Jonathan D

    2014-01-01

    Obesity is associated with inflammation that can drive metabolic defects such as hyperlipidemia and insulin resistance. Specific metabolites can contribute to inflammation, but nutrient intake and obesity are also associated with altered bacterial load in metabolic tissues (i.e. metabolic endotoxemia). These bacterial cues can contribute to obesity-induced inflammation. The specific bacterial components and host receptors that underpin altered metabolic responses are emerging. We previously showed that Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) activation with bacterial peptidoglycan (PGN) caused insulin resistance in mice. We now show that PGN induces cell-autonomous lipolysis in adipocytes via NOD1. Specific bacterial PGN motifs stimulated lipolysis in white adipose tissue (WAT) explants from WT, but not NOD1⁻/⁻mice. NOD1-activating PGN stimulated mitogen activated protein kinases (MAPK),protein kinase A (PKA), and NF-κB in 3T3-L1 adipocytes. The NOD1-mediated lipolysis response was partially reduced by inhibition of ERK1/2 or PKA alone, but not c-Jun N-terminal kinase (JNK). NOD1-stimulated lipolysis was partially dependent on NF-κB and was completely suppressed by inhibiting ERK1/2 and PKA simultaneously or hormone sensitive lipase (HSL). Our results demonstrate that bacterial PGN stimulates lipolysis in adipocytes by engaging a stress kinase, PKA, NF-κB-dependent lipolytic program. Bacterial NOD1 activation is positioned as a component of metabolic endotoxemia that can contribute to hyperlipidemia, systemic inflammation and insulin resistance by acting directly on adipocytes.

  10. Bacterial Peptidoglycan Stimulates Adipocyte Lipolysis via NOD1

    PubMed Central

    Henriksbo, Brandyn D.; Cavallari, Joseph F.; Foley, Kevin P.; Schertzer, Jonathan D.

    2014-01-01

    Obesity is associated with inflammation that can drive metabolic defects such as hyperlipidemia and insulin resistance. Specific metabolites can contribute to inflammation, but nutrient intake and obesity are also associated with altered bacterial load in metabolic tissues (i.e. metabolic endotoxemia). These bacterial cues can contribute to obesity-induced inflammation. The specific bacterial components and host receptors that underpin altered metabolic responses are emerging. We previously showed that Nucleotide-binding oligomerization domain-containing protein 1 (NOD1) activation with bacterial peptidoglycan (PGN) caused insulin resistance in mice. We now show that PGN induces cell-autonomous lipolysis in adipocytes via NOD1. Specific bacterial PGN motifs stimulated lipolysis in white adipose tissue (WAT) explants from WT, but not NOD1−/− mice. NOD1-activating PGN stimulated mitogen activated protein kinases (MAPK),protein kinase A (PKA), and NF-κB in 3T3-L1 adipocytes. The NOD1-mediated lipolysis response was partially reduced by inhibition of ERK1/2 or PKA alone, but not c-Jun N-terminal kinase (JNK). NOD1-stimulated lipolysis was partially dependent on NF-κB and was completely suppressed by inhibiting ERK1/2 and PKA simultaneously or hormone sensitive lipase (HSL). Our results demonstrate that bacterial PGN stimulates lipolysis in adipocytes by engaging a stress kinase, PKA, NF-κB-dependent lipolytic program. Bacterial NOD1 activation is positioned as a component of metabolic endotoxemia that can contribute to hyperlipidemia, systemic inflammation and insulin resistance by acting directly on adipocytes. PMID:24828250

  11. Nutritional state modulates growth hormone-stimulated lipolysis.

    PubMed

    Bergan, Heather E; Kittilson, Jeffrey D; Sheridan, Mark A

    2015-01-01

    Growth hormone (GH) regulates several processes in vertebrates, including two metabolically disparate processes: promotion of growth, an anabolic action, and mobilization of stored lipid, a catabolic action. In this study, we used hepatocytes isolated from continuously fed and long-term (4weeks) fasted rainbow trout (Oncorhynchus mykiss) as a model to investigate the mechanistic basis of the anabolic and catabolic actions of GH. Our hypothesis was that nutritional state modulates the lipolytic responsiveness of cells by adjusting the signal transduction pathways to which GH links. GH stimulated lipolysis as measured by increased glycerol release in both a time- and concentration-related manner from cells of fasted fish but not from cells of fed fish. Expression of mRNAs that encode the lipolytic enzyme hormone-sensitive lipase (HSL), HSL1 and HSL2, also was stimulated by GH in cells from fasted fish and not in cells from fed fish. Activation of the signaling pathways that mediate GH action also was studied. In cells from fed fish, GH activated the JAK-STAT, PI3K-Akt, and ERK pathways, whereas in cells from fasted fish, GH activated the PLC/PKC and ERK pathways. In hepatocytes from fasted fish, blockade of PLC/PKC and of the ERK pathway inhibited GH-stimulated lipolysis and GH-stimulated HSL mRNA expression, whereas blockade of JAK-STAT or of the PI3K-Akt pathway had no effect on lipolysis or HSL expression stimulated by GH. These results indicate that during fasting GH activates the PLC/PKC and ERK pathways resulting in lipolysis but during periods of feeding GH activates a different complement of signal elements that do not promote lipolysis. These findings suggest that the responsiveness of cells to GH depends on the signal pathways to which GH links and helps resolve the growth-promoting and lipid catabolic actions of GH.

  12. Rosiglitazone regulates IL-6-stimulated lipolysis in porcine adipocytes.

    PubMed

    Yang, Yongqing; Yang, Gongshe

    2010-10-01

    Interleukin (IL)-6, a proinflammatory cytokine, stimulates adipocyte lipolysis and induces insulin resistance in obese and diabetic subjects. However, the effects of the anti-diabetic drug rosiglitazone on IL-6-stimulated lipolysis and the underlying molecular mechanism are largely unknown. In this study, we demonstrated that rosiglitazone suppressed IL-6-stimulated lipolysis in differentiated porcine adipocytes by inactivation of extracellular signal-related kinase (ERK). Meanwhile, rosiglitazone enhanced the lipolysis response of adipocytes to isoprenaline. In addition, rosiglitazone significantly reversed IL-6-induced down-regulation of several genes such as perilipin A, peroxisome proliferators activated receptor gamma (PPARγ), and fatty acid synthetase, as well as the up-regulation of IL-6 mRNA. However, mRNA expression of PPARγ coactivator-1 alpha (PCG-1α) was enhanced by rosiglitazone in IL-6-stimulated adipocytes. These results indicate that rosiglitazone suppresses IL-6-stimulated lipolysis in porcine adipocytes through multiple molecular mechanisms.

  13. Germacrone inhibits adipogenesis and stimulates lipolysis via the AMP-activated protein kinase signalling pathway in 3T3-L1 preadipocytes.

    PubMed

    Guo, Yuan-Ri; Choung, Se-Young

    2017-02-01

    In a previous study, we reported that Aster spathulifolius Maxim extract (ASE) inhibited lipid accumulation and adipocyte differentiation in 3T3-L1 cells. Of the components in ASE, germacrone (GM) was identified as a potent bioactive constituent. GM is known for its anticancer and antiviral activity. However, the effects of GM and the molecular mechanism by which GM regulates adipogenesis and lipolysis were not reported. Therefore, we investigated the effect of GM on adipogenesis and lipolysis and to elucidate its underlying molecular mechanism. We analysed the contents of intracellular triglyceride and carried out Western blotting and RT-qPCR to investigate the underlying mechanism. We demonstrate that GM suppresses adipogenic differentiation and the increase in lipolysis in 3T3-L1 cells. In particular, GM down-regulates the expression of early adipogenesis-related genes (e.g. KLF4, KLF5, C/EBP-β and C/EBP-δ) and major adipogenesis-related genes (C/EBP-α and PPAR-γ). Furthermore, GM increases the protein levels of phosphorylated AMP-activated protein kinase α (AMPKα), phosphorylated acetyl-coenzyme A carboxylase (ACC) and carnitine palmitoyltransferase (CPT1). Our results suggest that GM may be a potent bioactive anti-adipogenic and lipolytic constituent via the regulation of adipogenesis, lipolysis and the AMPKα pathway. © 2016 Royal Pharmaceutical Society.

  14. Catecholamine-induced lipolysis causes mTOR complex dissociation and inhibits glucose uptake in adipocytes

    PubMed Central

    Mullins, Garrett R.; Wang, Lifu; Raje, Vidisha; Sherwood, Samantha G.; Grande, Rebecca C.; Boroda, Salome; Eaton, James M.; Blancquaert, Sara; Roger, Pierre P.; Leitinger, Norbert; Harris, Thurl E.

    2014-01-01

    Anabolic and catabolic signaling oppose one another in adipose tissue to maintain cellular and organismal homeostasis, but these pathways are often dysregulated in metabolic disorders. Although it has long been established that stimulation of the β-adrenergic receptor inhibits insulin-stimulated glucose uptake in adipocytes, the mechanism has remained unclear. Here we report that β-adrenergic–mediated inhibition of glucose uptake requires lipolysis. We also show that lipolysis suppresses glucose uptake by inhibiting the mammalian target of rapamycin (mTOR) complexes 1 and 2 through complex dissociation. In addition, we show that products of lipolysis inhibit mTOR through complex dissociation in vitro. These findings reveal a previously unrecognized intracellular signaling mechanism whereby lipolysis blocks the phosphoinositide 3-kinase–Akt–mTOR pathway, resulting in decreased glucose uptake. This previously unidentified mechanism of mTOR regulation likely contributes to the development of insulin resistance. PMID:25422441

  15. Catecholamine-induced lipolysis causes mTOR complex dissociation and inhibits glucose uptake in adipocytes.

    PubMed

    Mullins, Garrett R; Wang, Lifu; Raje, Vidisha; Sherwood, Samantha G; Grande, Rebecca C; Boroda, Salome; Eaton, James M; Blancquaert, Sara; Roger, Pierre P; Leitinger, Norbert; Harris, Thurl E

    2014-12-09

    Anabolic and catabolic signaling oppose one another in adipose tissue to maintain cellular and organismal homeostasis, but these pathways are often dysregulated in metabolic disorders. Although it has long been established that stimulation of the β-adrenergic receptor inhibits insulin-stimulated glucose uptake in adipocytes, the mechanism has remained unclear. Here we report that β-adrenergic-mediated inhibition of glucose uptake requires lipolysis. We also show that lipolysis suppresses glucose uptake by inhibiting the mammalian target of rapamycin (mTOR) complexes 1 and 2 through complex dissociation. In addition, we show that products of lipolysis inhibit mTOR through complex dissociation in vitro. These findings reveal a previously unrecognized intracellular signaling mechanism whereby lipolysis blocks the phosphoinositide 3-kinase-Akt-mTOR pathway, resulting in decreased glucose uptake. This previously unidentified mechanism of mTOR regulation likely contributes to the development of insulin resistance.

  16. TNF-α reduces g0s2 expression and stimulates lipolysis through PPAR-γ inhibition in 3T3-L1 adipocytes.

    PubMed

    Jin, Dan; Sun, Jun; Huang, Jing; He, Yiduo; Yu, An; Yu, Xiaoling; Yang, Zaiqing

    2014-10-01

    Tumor necrosis factor-α (TNF-α) is a multifunctional cytokine that acts as a mediator of obesity-linked insulin resistance (IR). It is commonly accepted that macrophage-derived TNF-α acts in a paracrine manner on adjacent adipocytes, induces lipolysis, which contributes to obesity-linked hyperglycemia. Several studies suggested that G0/G1 switch gene 2 (g0s2) was up-regulated during adipogenesis, and its protein could be degraded in response to TNF-α stimulation. The aim of the present work was to investigate the transcriptional regulation of g0s2 by TNF-α stimulation. In this study, 3T3-L1 pre-adipocytes were differentiated, and treated with TNF-α for 24h. The effects of TNF-α on lipolysis and lipase expression were then examined. Our results revealed that TNF-α exerted dose- and time-dependent lipolytic effects, which could be partially reversed by overexpression of g0s2 and peroxisome proliferator-activated receptor-γ (ppar-γ). In addition, TNF-α treatment significantly reduced the expression of adiponectin, ppar-γ, hormone-sensitive Lipase (hsl), adipose triglyceride lipase (atgl) as well as ATGL co-factors. Interestingly, TNF-α significantly decreased adiponectin and PPAR-γ protein levels, while treatment with the proteasomal inhibitor MG-132 maintained PPAR-γ levels. Degradation of PPAR-γ almost completely abolished the binding of PPAR-γ to the g0s2 promoter in adipocytes treated with TNF-α. We propose that proteasomal degradation of PPAR-γ and the reduction of g0s2 content are permissive for prolonged TNF-α induced lipolysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. ADP-ribosylation factor 6 modulates adrenergic stimulated lipolysis in adipocytes

    PubMed Central

    Liu, Yingqiu; Zhou, Dequan; Abumrad, Nada A.

    2010-01-01

    ADP-ribosylation factor 6 (Arf6) is a small GTPase that influences membrane receptor trafficking and the actin cytoskeleton. In adipocytes, Arf6 regulates the trafficking of the glucose transporter type 4 (GLUT4) and consequently insulin-stimulated glucose transport. Previous studies also indicated a role of Arf6 in adrenergic receptor trafficking, but whether this contributes to the control of lipolysis in adipocytes remains unknown. This was examined in the present study by using RNA interference (RNAi) and pharmaceutical inhibition in murine cultured 3T3-L1 adipocytes. Downregulation of Arf6 by RNAi impairs isoproterenol-stimulated lipolysis specifically but does not alter triacylglycerol (TAG) synthesis or the insulin signaling pathway. Neither total TAG amounts nor TAG fatty acid compositions are altered. The inhibitory effect on lipolysis is mimicked by dynasore, a specific inhibitor for dynamin, which is required for endocytosis. In contrast, lipolysis triggered by reagents that bypass events at the plasma membrane (e.g., forskolin, isobutylmethylxanthine or 8-bromo-cAMP) is not affected. Moreover, Arf6 protein levels in white adipose tissues are markedly increased in ob/ob mice, whereas they are decreased in obesity-resistant CD36 null mice. These changes reflect at least in part alterations in Arf6 mRNA levels. Collectively, these results suggest a role of the endocytic pathway and its regulation by Arf6 in adrenergic stimulation of lipolysis in adipocytes and potentially in the development of obesity. PMID:20107045

  18. Adipocyte lipolysis-stimulated interleukin-6 production requires sphingosine kinase 1 activity.

    PubMed

    Zhang, Wenliang; Mottillo, Emilio P; Zhao, Jiawei; Gartung, Allison; VanHecke, Garrett C; Lee, Jen-Fu; Maddipati, Krishna R; Xu, Haiyan; Ahn, Young-Hoon; Proia, Richard L; Granneman, James G; Lee, Menq-Jer

    2014-11-14

    Adipocyte lipolysis can increase the production of inflammatory cytokines such as interleukin-6 (IL-6) that promote insulin resistance. However, the mechanisms that link lipolysis with inflammation remain elusive. Acute activation of β3-adrenergic receptors (ADRB3) triggers lipolysis and up-regulates production of IL-6 in adipocytes, and both of these effects are blocked by pharmacological inhibition of hormone-sensitive lipase. We report that stimulation of ADRB3 induces expression of sphingosine kinase 1 (SphK1) and increases sphingosine 1-phosphate production in adipocytes in a manner that also depends on hormone-sensitive lipase activity. Mechanistically, we found that adipose lipolysis-induced SphK1 up-regulation is mediated by the c-Jun N-terminal kinase (JNK)/activating protein-1 signaling pathway. Inhibition of SphK1 by sphingosine kinase inhibitor 2 diminished the ADRB3-induced IL-6 production both in vitro and in vivo. Induction of IL-6 by ADRB3 activation was suppressed by siRNA knockdown of Sphk1 in cultured adipocytes and was severely attenuated in Sphk1 null mice. Conversely, ectopic expression of SphK1 increased IL-6 expression in adipocytes. Collectively, these data demonstrate that SphK1 is a critical mediator in lipolysis-triggered inflammation in adipocytes. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Diabetes decreases sensitivity of adipocyte lipolysis to inhibition by Gi-linked receptor agonists.

    PubMed

    Saggerson, D; Orford, M; Chatzipanteli, K; Shepherd, J

    1991-01-01

    (1) Streptozotocin-diabetes decreased the responsiveness of noradrenaline- or forskolin-stimulated lipolysis to inhibition by phenylisopropyladenosine (PIA), prostaglandin E1 (PGE1) and nicotinate in rat adipocytes. (2) Diabetes had no effect on high affinity binding of [3H]PIA to adipocyte plasma membranes. (3) Plasma membranes from diabetic animals had increased abundance of alpha-subunits of Gi1 and Gi2. The effect of pertussis toxin in overcoming inhibition of lipolysis by PIA was delayed in adipocytes from diabetic rats. (4) Diabetes decreased the GTP-dependent right-wards shift in the dose-curve for displacement of the antagonist [3H]DPCPX by PIA in adipocyte plasma membranes. (5) It is concluded that, despite increased abundance of Gi in diabetic adipocytes, less of this is functional. This may contribute to reduced sensitivity to PIA, PGE1 and nicotinate and explains some of the loss of control of lipolysis in insulin-dependent diabetes.

  20. Guanylin and uroguanylin stimulate lipolysis in human visceral adipocytes.

    PubMed

    Rodríguez, A; Gómez-Ambrosi, J; Catalán, V; Ezquerro, S; Méndez-Giménez, L; Becerril, S; Ibáñez, P; Vila, N; Margall, M A; Moncada, R; Valentí, V; Silva, C; Salvador, J; Frühbeck, G

    2016-09-01

    Uroguanylin and guanylin are secreted by intestinal epithelial cells as prohormones postprandially and act on the hypothalamus to induce satiety. The impact of obesity and obesity-associated type 2 diabetes (T2D) on proguanylin and prouroguanylin expression/secretion as well as the potential role of guanylin and uroguanylin in the control of lipolysis in humans was evaluated. Circulating and gastrointestinal expression of proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were measured in 134 subjects. In addition, plasma proguanylin and prouroguanylin were measured before and after weight loss achieved either by Roux-en-Y gastric bypass (RYGB) (n=24) or after a conventional diet (n=15). The effect of guanylin and uroguanylin (1-100 nmol l(-1)) on lipolysis was determined in vitro in omental adipocytes. Circulating concentrations of prouroguanylin, but not proguanylin, were decreased in obesity in relation to adiposity. Weight loss achieved by RYGB increased plasma proguanylin and prouroguanylin. Obese T2D individuals showed higher expression of intestinal GUCA2A as well as of the receptors of the guanylin system, GUCY2C and GUCY2D, in omental adipocytes. The incubation with guanylin and uroguanylin significantly stimulated lipolysis in differentiated omental adipocytes, as evidenced by hormone-sensitive lipase phosphorylation at Ser563, an increase in fatty acids and glycerol release together with an upregulation of several lipolysis-related genes, including AQP3, AQP7, FATP1 or CD36. Both guanylin and uroguanylin trigger lipolysis in human visceral adipocytes. Given the lipolytic action of the guanylin system on visceral adipocytes, the herein reported decrease of circulating prouroguanylin concentrations in obese patients may have a role in excessive fat accumulation in obesity.

  1. The Role of PDE3B Phosphorylation in the Inhibition of Lipolysis by Insulin

    PubMed Central

    DiPilato, Lisa M.; Ahmad, Faiyaz; Harms, Matthew; Seale, Patrick; Manganiello, Vincent

    2015-01-01

    Inhibition of adipocyte lipolysis by insulin is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance and type 2 diabetes mellitus. The main target of the antilipolytic action of insulin is believed to be phosphodiesterase 3B (PDE3B), whose phosphorylation by Akt leads to accelerated degradation of the prolipolytic second messenger cyclic AMP (cAMP). To test this hypothesis genetically, brown adipocytes lacking PDE3B were examined for their regulation of lipolysis. In Pde3b knockout (KO) adipocytes, insulin was unable to suppress β-adrenergic receptor-stimulated glycerol release. Reexpressing wild-type PDE3B in KO adipocytes fully rescued the action of insulin against lipolysis. Surprisingly, a mutant form of PDE3B that ablates the major Akt phosphorylation site, murine S273, also restored the ability of insulin to suppress lipolysis. Taken together, these data suggest that phosphorylation of PDE3B by Akt is not required for insulin to suppress adipocyte lipolysis. PMID:26031333

  2. The Role of PDE3B Phosphorylation in the Inhibition of Lipolysis by Insulin.

    PubMed

    DiPilato, Lisa M; Ahmad, Faiyaz; Harms, Matthew; Seale, Patrick; Manganiello, Vincent; Birnbaum, Morris J

    2015-08-01

    Inhibition of adipocyte lipolysis by insulin is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance and type 2 diabetes mellitus. The main target of the antilipolytic action of insulin is believed to be phosphodiesterase 3B (PDE3B), whose phosphorylation by Akt leads to accelerated degradation of the prolipolytic second messenger cyclic AMP (cAMP). To test this hypothesis genetically, brown adipocytes lacking PDE3B were examined for their regulation of lipolysis. In Pde3b knockout (KO) adipocytes, insulin was unable to suppress β-adrenergic receptor-stimulated glycerol release. Reexpressing wild-type PDE3B in KO adipocytes fully rescued the action of insulin against lipolysis. Surprisingly, a mutant form of PDE3B that ablates the major Akt phosphorylation site, murine S273, also restored the ability of insulin to suppress lipolysis. Taken together, these data suggest that phosphorylation of PDE3B by Akt is not required for insulin to suppress adipocyte lipolysis. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  3. Inhibition of rat fat cell lipolysis by monoamine oxidase and semicarbazide-sensitive amine oxidase substrates.

    PubMed

    Visentin, Virgile; Prévot, Danielle; Marti, Luc; Carpéné, Christian

    2003-04-18

    It has been demonstrated that amine oxidase substrates stimulate glucose transport in cardiomyocytes and adipocytes, promote adipogenesis in pre-adipose cell lines and lower blood glucose in diabetic rats. These insulin-like effects are dependent on amine oxidation by semicarbazide-sensitive amine oxidase or by monoamine oxidase. The present study aimed to investigate whether amine oxidase substrates also exhibit another insulin-like property, the inhibition of lipolysis. We therefore tested the influence of tyramine and benzylamine on lipolytic activity in rat adipocytes. These amines did not modify basal lipolysis but dose-dependently counteracted the stimulation induced by lipolytic agents. The response to 10 nM isoprenaline was totally inhibited by tyramine 1 mM. The blockade produced by inhibition of amine oxidase activity or by 1 mM glutathione suggested that the generation of oxidative species, which occurs during amine oxidation, was involved in tyramine antilipolytic effect. Among the products resulting from amine oxidation, only hydrogen peroxide was antilipolytic in a manner that was potentiated by vanadate, as for tyramine or benzylamine. Antilipolytic responses to tyramine and to insulin were sensitive to wortmannin. These data suggest that inhibition of lipolysis is a novel insulin-like effect of amine oxidase substrates which is mediated by hydrogen peroxide generated during amine oxidation.

  4. Eicosapentaenoic acid inhibits tumour necrosis factor-α-induced lipolysis in murine cultured adipocytes.

    PubMed

    Lorente-Cebrián, Silvia; Bustos, Matilde; Marti, Amelia; Fernández-Galilea, Marta; Martinez, J Alfredo; Moreno-Aliaga, Maria J

    2012-03-01

    Eicosapentaenoic acid (EPA) is an omega-3 polyunsaturated fatty acid with beneficial effects in obesity and insulin resistance. High levels of proinflammatory cytokine tumour necrosis factor-α (TNF-α) in obesity promote lipolysis in adipocytes, leading to the development of insulin resistance. Thus, the aims of the present study were to analyze the potential antilipolytic properties of EPA on cytokine-induced lipolysis and to investigate the possible mechanisms involved. The EPA effects on basal and TNF-α-induced lipolysis were determined in both primary rat and 3T3-L1 adipocytes. Treatment of primary rat adipocytes with EPA (100 and 200 μM) significantly decreased basal glycerol release (P<.01) and prevented cytokine-induced lipolysis in a dose-dependent manner (P<.001). Moreover, EPA decreased TNF-α-induced activation of nuclear factor-κB and extracellular-related kinase 1/2 phosphorylation. In addition, the antilipolytic action of EPA was stimulated by the AMP-kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-b-d-ribofuranoside and blocked by the AMPK-inhibitor compound C. Moreover, we found that EPA stimulated hormone-sensitive lipase (HSL) phosphorylation on serine-565, which further supports the involvement of AMPK in EPA's antilipolytic actions. Eicosapentaenoic acid treatment (24 h), alone and in the presence of TNF-α, also decreased adipose triglyceride lipase (ATGL) protein content in cultured adipocytes. However, oral supplementation with EPA for 35 days was able to partially reverse the down-regulation of HSL and ATGL messenger RNA observed in retroperitoneal adipose tissue of high-fat-diet-fed rats. These findings suggest that EPA inhibits proinflammatory cytokine-induced lipolysis in adipocytes. This effect might contribute to explain the insulin-sensitizing properties of EPA. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Desensitization of adenosine receptor-mediated inhibition of lipolysis. The mechanism involves the development of enhanced cyclic adenosine monophosphate accumulation in tolerant adipocytes.

    PubMed Central

    Hoffman, B B; Chang, H; Dall'Aglio, E; Reaven, G M

    1986-01-01

    Adipocytes contain adenosine receptors, termed A1 receptors, which inhibit lipolysis by decreasing adenylate cyclase activity. The inhibition of lipolysis by adenosine agonists in vivo acutely suppresses the plasma concentrations of free fatty acids (FFA) and triglycerides. We have found that infusions of the adenosine receptor agonist phenylisopropyladenosine (PIA) initially decreases plasma FFA concentrations; however, with prolonged exposure (6 d), rats become very tolerant to the effects of the drug. Adipocytes isolated from epididymal fat pads from PIA-infused rats have altered lipolytic responses. When lipolysis is stimulated with a relatively high concentration of isoproterenol (10(-7) M), PIA does not inhibit lipolysis in adipocytes from the infused animals. However, PIA inhibits isoproterenol-stimulated cyclic AMP (cAMP) accumulation in adipocytes from the infused rats although with decreased sensitivity compared with controls. The explanation for the impaired antilipolytic effect appears to be due to the fact that isoproterenol-stimulated cAMP accumulation is markedly increased in cells from infused rats. Indeed, basal lipolysis and lipolysis stimulated with lower concentrations of isoproterenol (10(-9), 10(-8) M) are effectively inhibited by PIA. cAMP accumulation is greatly increased in adipocytes from infused rats when stimulated by isoproterenol, ACTH, and forskolin. The results have some striking analogies to changes induced in nerve cells by prolonged exposure to narcotics. These data suggest that tolerance to PIA develops in adipocytes as a consequence of enhanced cAMP accumulation. PMID:3013937

  6. Ex vivo study of incorporation into adipocytes and lipolysis-inhibition effect of polycyclic aromatic hydrocarbons.

    PubMed

    Irigaray, P; Lacomme, S; Mejean, L; Belpomme, D

    2009-05-22

    We have previously shown that benzo[a]pyrene (B[a]P) administrated at extremely low dose can cause weight gain in mice and that the increase in adipose tissue mass is due to inhibition of beta-adrenergic stimulation of lipolysis. Moreover we have suggested that in addition to its endocrine properties, adipose tissue act as a reservoir for many chemical carcinogens including Polycyclic Aromatic Hydrocarbons (PAHs). In this paper we show that B[a]P as well as the two C4 PAHs, pyrene and phenanthrene can bioaccumulate into adipocytes in a similar manner, but that at the difference of B[a]P, have no impact on epinephrine-induced lipolysis. On the basis of this ex vivo study, we therefore suggest that B[a]P may play a central role in carcinogenesis not only by inducing cancer through its mutagenic properties, but also by increasing the bioaccumulation capacity of the adipose tissue mass.

  7. Curcumin attenuates lipolysis stimulated by tumor necrosis factor-α or isoproterenol in 3T3-L1 adipocytes.

    PubMed

    Xie, Xiao-yun; Kong, Po-Ren; Wu, Jin-feng; Li, Ying; Li, Yan-xiang

    2012-12-15

    Curcumin, an active component derived from dietary spice turmeric (Curcuma longa), has been demonstrated antihyperglycemic, antiinflammatory and hypocholesterolemic activities in obesity and diabetes. These effects are associated with decreased level of circulating free fatty acids (FFA), however the mechanism has not yet been elucidated. The flux of FFA and glycerol from adipose tissue to the blood stream primarily depends on the lipolysis of triacylglycerols in the adipocytes. Adipocyte lipolysis is physiologically stimulated by catecholamine hormones. Tumor necrosis factor-α (TNFα) stimulates chronic lipolysis in obesity and type 2 diabetes. In this study, we examined the role of curcumin in inhibiting lipolytic action upon various stimulations in 3T3-L1 adipocytes. Glycerol release from TNFα or isoproterenol-stimulated 3T3-L1 adipocytes in the absence or presence of curcumin was determined using a colorimetric assay (GPO-Trinder). Western blotting was used to investigate the TNFα-induced phosphorylation of MAPK and perilipin expression. Fatcake and cytosolic fractions were prepared to examine the isoproterenol-stimulated hormone-sensitive lipase translocation. Treatment with curcumin attenuated TNFα-mediated lipolysis by suppressing phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2) and reversing the downregulation of perilipin protein in TNFα-stimulated adipocytes (p<0.05). The acute lipolytic response to adrenergic stimulation of isoproterenol was also restricted by curcumin (10-20 μM, p<0.05), which was compatible with reduced perilipin phosphorylation(29%, p<0.05) and hormone-sensitive lipase translocation(20%, p<0.05). This study provides evidence that curcumin acts on adipocytes to suppress the lipolysis response to TNFα and catecholamines. The antilipolytic effect could be a cellular basis for curcumin decreasing plasma FFA levels and improving insulin sensitivity. Copyright © 2012 Elsevier GmbH. All rights reserved.

  8. Contraction-induced lipolysis is not impaired by inhibition of hormone-sensitive lipase in skeletal muscle

    PubMed Central

    Alsted, Thomas J; Ploug, Thorkil; Prats, Clara; Serup, Annette K; Høeg, Louise; Schjerling, Peter; Holm, Cecilia; Zimmermann, Robert; Fledelius, Christian; Galbo, Henrik; Kiens, Bente

    2013-01-01

    In skeletal muscle hormone-sensitive lipase (HSL) has long been accepted to be the principal enzyme responsible for lipolysis of intramyocellular triacylglycerol (IMTG) during contractions. However, this notion is based on in vitro lipase activity data, which may not reflect the in vivo lipolytic activity. We investigated lipolysis of IMTG in soleus muscles electrically stimulated to contract ex vivo during acute pharmacological inhibition of HSL in rat muscles and in muscles from HSL knockout (HSL-KO) mice. Measurements of IMTG are complicated by the presence of adipocytes located between the muscle fibres. To circumvent the problem with this contamination we analysed intramyocellular lipid droplet content histochemically. At maximal inhibition of HSL in rat muscles, contraction-induced breakdown of IMTG was identical to that seen in control muscles (P < 0.001). In response to contractions IMTG staining decreased significantly in both HSL-KO and WT muscles (P < 0.05). In vitro TG hydrolase activity data revealed that adipose triglyceride lipase (ATGL) and HSL collectively account for ∼98% of the TG hydrolase activity in mouse skeletal muscle, other TG lipases accordingly being of negligible importance for lipolysis of IMTG. The present study is the first to demonstrate that contraction-induced lipolysis of IMTG occurs in the absence of HSL activity in rat and mouse skeletal muscle. Furthermore, the results suggest that ATGL is activated and plays a major role in lipolysis of IMTG during muscle contractions. PMID:23878361

  9. Contraction-induced lipolysis is not impaired by inhibition of hormone-sensitive lipase in skeletal muscle.

    PubMed

    Alsted, Thomas J; Ploug, Thorkil; Prats, Clara; Serup, Annette K; Høeg, Louise; Schjerling, Peter; Holm, Cecilia; Zimmermann, Robert; Fledelius, Christian; Galbo, Henrik; Kiens, Bente

    2013-10-15

    In skeletal muscle hormone-sensitive lipase (HSL) has long been accepted to be the principal enzyme responsible for lipolysis of intramyocellular triacylglycerol (IMTG) during contractions. However, this notion is based on in vitro lipase activity data, which may not reflect the in vivo lipolytic activity. We investigated lipolysis of IMTG in soleus muscles electrically stimulated to contract ex vivo during acute pharmacological inhibition of HSL in rat muscles and in muscles from HSL knockout (HSL-KO) mice. Measurements of IMTG are complicated by the presence of adipocytes located between the muscle fibres. To circumvent the problem with this contamination we analysed intramyocellular lipid droplet content histochemically. At maximal inhibition of HSL in rat muscles, contraction-induced breakdown of IMTG was identical to that seen in control muscles (P < 0.001). In response to contractions IMTG staining decreased significantly in both HSL-KO and WT muscles (P < 0.05). In vitro TG hydrolase activity data revealed that adipose triglyceride lipase (ATGL) and HSL collectively account for ∼98% of the TG hydrolase activity in mouse skeletal muscle, other TG lipases accordingly being of negligible importance for lipolysis of IMTG. The present study is the first to demonstrate that contraction-induced lipolysis of IMTG occurs in the absence of HSL activity in rat and mouse skeletal muscle. Furthermore, the results suggest that ATGL is activated and plays a major role in lipolysis of IMTG during muscle contractions.

  10. EPA-enriched phospholipids ameliorate cancer-associated cachexia mainly via inhibiting lipolysis.

    PubMed

    Du, Lei; Yang, Yu-Hong; Wang, Yu-Ming; Xue, Chang-Hu; Kurihara, Hideyuki; Takahashi, Koretaro

    2015-12-01

    Excessive loss of fat mass is considered as a key feature of body weight loss in cancer-associated cachexia (CAC). It affects the efficacy and tolerability of cancer therapy and reduces the quality and length of cancer patients' lives. The aim of the present study was to evaluate the effects of EPA-enriched phospholipids (EPA-PL) derived from starfish Asterias amurensis on cachectic weight loss in mice bearing S180 ascitic tumor, and TNF-α-stimulated lipolysis in 3T3-L1 adipocytes and to elucidate the possible mechanisms involved. Our findings revealed that oral administration of EPA-PL at 100 mg per kg body weight (BW) per day for 14 days prevented body weight loss in CAC mice by preserving the white adipose tissue (WAT) mass. We found that serum levels of nonesterified fatty acid (NEFA) and pro-inflammatory cytokines such as tumor necrosis factor α (TNF-α) and interleukin (IL)-6 increased in CAC mice but decreased significantly after oral treatment of EPA-PL. In addition, EPA-PL treatment also suppressed the overexpression of several key lipolytic factors and raised the mRNA levels of some adipogenic factors in the WAT of CAC mice. Moreover, treatment of EPA-PL (200 and 400 μM) markedly inhibited TNF-α-stimulated lipolysis in adipocytes. Furthermore, the antilipolytic effects of EPA-PL were stimulated by the extracellular signal-regulated kinase 1/2 (ERK 1/2) inhibitor PD 98059 and blocked via the AMP-activated protein kinase (AMPK) inhibitor compound C and the phosphoinositide-3-kinase (PI3K) inhibitor LY 294002. Taken together, these data suggest that the dietary EPA-PL ameliorates CAC mainly via inhibiting lipolysis and at least in part for recovering the function of adipogenesis.

  11. Leucaena leucocephala fruit aqueous extract stimulates adipogenesis, lipolysis, and glucose uptake in primary rat adipocytes.

    PubMed

    Kuppusamy, Umah Rani; Arumugam, Bavani; Azaman, Nooriza; Jen Wai, Chai

    2014-01-01

    Leucaena leucocephala had been traditionally used to treat diabetes. The present study was designed to evaluate in vitro "insulin-like" activities of Leucaena leucocephala (Lam.) deWit. aqueous fruit extract on lipid and glucose metabolisms. The ability of the extract to stimulate adipogenesis, inhibit lipolysis, and activate radio-labeled glucose uptake was assessed using primary rat adipocytes. Quantitative Real-Time RT-PCR was performed to investigate effects of the extract on expression levels of genes (protein kinases B, AKT; glucose transporter 4, GLUT4; hormone sensitive lipase, HSL; phosphatidylinositol-3-kinases, PI3KA; sterol regulatory element binding factor 1, Srebp1) involved in insulin-induced signaling pathways. L. leucocephala aqueous fruit extract stimulated moderate adipogenesis and glucose uptake into adipocytes when compared to insulin. Generally, the extract exerted a considerable level of lipolytic effect at lower concentration but decreased gradually at higher concentration. The findings concurred with RT-PCR analysis. The expressions of GLUT4 and HSL genes were upregulated by twofold and onefold, respectively, whereas AKT, PI3KA, and Srebp1 genes were downregulated. The L. leucocephala aqueous fruit extract may be potentially used as an adjuvant in the treatment of Type 2 diabetes mellitus and weight management due to its enhanced glucose uptake and balanced adipogenesis and lipolysis properties.

  12. Leucaena leucocephala Fruit Aqueous Extract Stimulates Adipogenesis, Lipolysis, and Glucose Uptake in Primary Rat Adipocytes

    PubMed Central

    Kuppusamy, Umah Rani; Azaman, Nooriza; Jen Wai, Chai

    2014-01-01

    Leucaena leucocephala had been traditionally used to treat diabetes. The present study was designed to evaluate in vitro “insulin-like” activities of Leucaena leucocephala (Lam.) deWit. aqueous fruit extract on lipid and glucose metabolisms. The ability of the extract to stimulate adipogenesis, inhibit lipolysis, and activate radio-labeled glucose uptake was assessed using primary rat adipocytes. Quantitative Real-Time RT-PCR was performed to investigate effects of the extract on expression levels of genes (protein kinases B, AKT; glucose transporter 4, GLUT4; hormone sensitive lipase, HSL; phosphatidylinositol-3-kinases, PI3KA; sterol regulatory element binding factor 1, Srebp1) involved in insulin-induced signaling pathways. L. leucocephala aqueous fruit extract stimulated moderate adipogenesis and glucose uptake into adipocytes when compared to insulin. Generally, the extract exerted a considerable level of lipolytic effect at lower concentration but decreased gradually at higher concentration. The findings concurred with RT-PCR analysis. The expressions of GLUT4 and HSL genes were upregulated by twofold and onefold, respectively, whereas AKT, PI3KA, and Srebp1 genes were downregulated. The L. leucocephala aqueous fruit extract may be potentially used as an adjuvant in the treatment of Type 2 diabetes mellitus and weight management due to its enhanced glucose uptake and balanced adipogenesis and lipolysis properties. PMID:25180205

  13. B56alpha/protein phosphatase 2A inhibits adipose lipolysis in high-fat diet-induced obese mice.

    PubMed

    Kinney, Brice P; Qiao, Liping; Levaugh, Justin M; Shao, Jianhua

    2010-08-01

    Lipolysis and lipogenesis are two opposite processes that control lipid storage in adipocytes. Impaired adipose lipolysis has been observed in both obese human subjects and animal models. This study investigated the mechanisms underlying impaired adipose lipolysis in a high-fat diet-induced obese (DIO) mouse model. DIO models were created using male C57BL/6 mice. Our results show that beta3 adrenergic receptor-specific agonist BRL37344 induced adipose lipolysis was significantly blunted in DIO mice. The levels of Ser660 phosphorylation of hormone-sensitive lipase (HSL) were significantly decreased in the epididymal fat of DIO mice. However, protein levels of HSL, adipose triglyceride lipase and its coactivator comparative gene identification-58 were similar between DIO and control mice. It is known that upon lipolytic hormone stimulation, protein kinase A phosphorylates HSL Ser660 and activates HSL, whereas protein phosphatase 2A (PP2A) dephosphorylates and inactivates HSL. Interestingly, our study shows that high-fat feeding did not alter epididymal fat cAMP and protein kinase A protein levels but significantly increased the expression of the alpha-isoform of PP2A regulatory subunit B' (B56alpha). To study the role of B56alpha in obesity-associated lipolytic defect, B56alpha was overexpressed or knocked down by adenovirus-mediated gene transduction in cultured 3T3-L1CARDelta1 adipocytes. Overexpression of B56alpha significantly decreased HSL Ser660 phosphorylation. In contrast, knocking down B56alpha increased hormone-stimulated HSL activation and lipolysis in mature 3T3-L1CARDelta1 adipocytes. These results strongly suggest that elevated B56alpha/PP2A inhibits HSL and lipolysis in white adipose tissue of DIO mice.

  14. Uraemic sera stimulate lipolysis in human adipocytes: role of perilipin.

    PubMed

    Axelsson, Jonas; Aström, Gaby; Sjölin, Eva; Qureshi, Abdul Rashid; Lorente-Cebrián, Silvia; Stenvinkel, Peter; Rydén, Mikael

    2011-08-01

    Although chronic kidney disease (CKD) is associated with dyslipidaemia and insulin resistance, the exact cause(s) are unknown. Since adipose tissue plays an important role in the development of these complications, we investigated the effect of uraemic sera on human adipocytes in vitro. Cultured human adipocytes were incubated for 48 h with media containing sera from eight CKD Stage 5 patients or four (matched for age, sex and body mass index) healthy controls. Glycerol release (an index of lipolysis) was determined in conditioned media. RNA was isolated from the cells and quantitative polymerase chain reaction of genes involved in lipolysis was performed. In vivo lipolysis was determined by the plasma glycerol/total fat mass (from dual energy X-ray absorptiometry) ratio in 28 CKD patients and 28 matched controls. Incubation with uraemic, but not control, sera resulted in a significant ∼30% increase in spontaneous (basal) lipolysis (P <0.05). Furthermore, uraemic but not control sera induced a selective ∼30% reduction of messenger RNA (mRNA) coding for the lipid-droplet-associated protein perilipin (PLIN) (P <0.05), while mRNA levels of lipases, adipokines and differentiation factors did not differ between the groups after incubation. Also, consistent with our in vitro data, in vivo plasma glycerol/fat mass ratio was significantly elevated in uraemic patients as compared to controls (5.23 ± 4.1 versus 3.41 ± 2.3 μM/kg, P < 0.05). Undefined circulating factors in CKD patients increase basal lipolysis in human adipocytes in vitro, probably by attenuating the expression of the lipolytic regulator PLIN. Since in vivo lipolysis is a well-established risk factor for insulin resistance and cardiovascular disease, these effects may promote increased morbidity and mortality in CKD.

  15. Adipogenesis, lipogenesis and lipolysis is stimulated by mild but not severe hypoxia in 3T3-L1 cells.

    PubMed

    Weiszenstein, Martin; Musutova, Martina; Plihalova, Andrea; Westlake, Katerina; Elkalaf, Moustafa; Koc, Michal; Prochazka, Antonin; Pala, Jan; Gulati, Sumeet; Trnka, Jan; Polak, Jan

    2016-09-16

    In-vitro investigation of the effects of hypoxia is limited by physical laws of gas diffusion and cellular O2 consumption, making prolonged exposures to stable O2 concentrations impossible. Using a gas-permeable cultureware, chronic effects of mild and severe hypoxia on triglyceride accumulation, lipid droplet size distribution, spontaneous lipolysis and gene expression of adipocyte-specific markers were assessed. 3T3-L1 cells were differentiated under 20%, 4% or 1% O2 using a gas-permeable cultureware. Triglyceride accumulation, expression of genes characteristic for advanced adipocyte differentiation and involvement of key lipogenesis enzymes were assessed after exposures. Lipogenesis increased by 375% under mild hypoxia, but dropped by 43% in severe hypoxia. Mild, but not severe, hypoxia increased formation of large lipid droplets 6.4 fold and strongly induced gene expression of adipocyte-specific markers. Spontaneous lipolysis increased by 488% in mild, but only by 135% in severe hypoxia. Inhibition of ATP-dependent citrate lyase suppressed hypoxia-induced lipogenesis by 81% and 85%. Activation of HIF inhibited lipogenesis by 59%. Mild, but not severe, hypoxia stimulates lipolysis and promotes adipocyte differentiation, probably through excess of acetyl-CoA originating from tricarboxylic acid cycle independently of HIF activation.

  16. Ginsenoside Rg5 Inhibits Succinate-Associated Lipolysis in Adipose Tissue and Prevents Muscle Insulin Resistance

    PubMed Central

    Xiao, Na; Yang, Le-Le; Yang, Yi-Lin; Liu, Li-Wei; Li, Jia; Liu, Baolin; Liu, Kang; Qi, Lian-Wen; Li, Ping

    2017-01-01

    Endoplasmic reticulum (ER) stress, inflammation, and lipolysis occur simultaneously in adipose dysfunction and contribute to insulin resistance. This study was designed to investigate whether ginsenoside Rg5 could ameliorate adipose dysfunction and prevent muscle insulin resistance. Short-term high-fat diet (HFD) feeding induced hypoxia with ER stress in adipose tissue, leading to succinate accumulation due to the reversal of succinate dehydrogenase (SDH) activity. Rg5 treatment reduced cellular energy charge, suppressed ER stress and then prevented succinate accumulation in adipose tissue. Succinate promoted IL-1β production through NLRP3 inflammasome activation and then increased cAMP accumulation by impairing PDE3B expression, leading to increased lipolysis. Ginsenoside Rg5 treatment suppressed NLRP3 inflammasome activation, preserved PDE3B expression and then reduced cAMP accumulation, contributing to inhibition of lipolysis. Adipose lipolysis increased FFAs trafficking from adipose tissue to muscle. Rg5 reduced diacylglycerol (DAG) and ceramides accumulation, inhibited protein kinase Cθ translocation, and prevented insulin resistance in muscle. In conclusion, succinate accumulation in hypoxic adipose tissue acts as a metabolic signaling to link ER stress, inflammation and cAMP/PKA activation, contributing to lipolysis and insulin resistance. These findings establish a previously unrecognized role of ginsenosides in the regulation of lipid and glucose homeostasis and suggest that adipose succinate-associated NLRP3 inflammasome activation might be targeted therapeutically to prevent lipolysis and insulin resistance. PMID:28261091

  17. 3,5-Dihydroxybenzoic acid, a specific agonist for hydroxycarboxylic acid 1, inhibits lipolysis in adipocytes.

    PubMed

    Liu, Changlu; Kuei, Chester; Zhu, Jessica; Yu, Jingxue; Zhang, Li; Shih, Amy; Mirzadegan, Taraneh; Shelton, Jonathan; Sutton, Steven; Connelly, Margery A; Lee, Grace; Carruthers, Nicholas; Wu, Jiejun; Lovenberg, Timothy W

    2012-06-01

    Niacin raises high-density lipoprotein and lowers low-density lipoprotein through the activation of the β-hydroxybutyrate receptor hydroxycarboxylic acid 2 (HCA2) (aka GPR109a) but with an unwanted side effect of cutaneous flushing caused by vascular dilation because of the stimulation of HCA2 receptors in Langerhans cells in skin. HCA1 (aka GPR81), predominantly expressed in adipocytes, was recently identified as a receptor for lactate. Activation of HCA1 in adipocytes by lactate results in the inhibition of lipolysis, suggesting that agonists for HCA1 may be useful for the treatment of dyslipidemia. Lactate is a metabolite of glucose, suggesting that HCA1 may also be involved in the regulation of glucose metabolism. The low potency of lactate to activate HCA1, coupled with its fast turnover rate in vivo, render it an inadequate tool for studying the biological role of lactate/HCA1 in vivo. In this article, we demonstrate the identification of 3-hydroxybenzoic acid (3-HBA) as an agonist for both HCA2 and HCA1, whereas 3,5-dihydroxybenzoic acid (3,5-DHBA) is a specific agonist for only HCA1 (EC(50) ∼150 μM). 3,5-DHBA inhibits lipolysis in wild-type mouse adipocytes but not in HCA1-deficient adipocytes. Therefore, 3,5-DHBA is a useful tool for the in vivo study of HCA1 function and offers a base for further HCA1 agonist design. Because 3-HBA and 3,5-DHBA are polyphenolic acids found in many natural products, such as fruits, berries, and coffee, it is intriguing to speculate that other heretofore undiscovered natural substances may have therapeutic benefits.

  18. Crotonis Fructus and Its Constituent, Croton Oil, Stimulate Lipolysis in OP9 Adipocytes

    PubMed Central

    Kim, Mi-Seong; Kim, Ha-Rim; So, Hong-Seob; Lee, Young-Rae; Moon, Hyoung-Chul; Ryu, Do-Gon; Yang, Sei-Hoon; Lee, Guem-San; Song, Je-Ho; Kwon, Kang-Beom

    2014-01-01

    Introduction. Crotonis fructus (CF) is the mature fruit of Croton tiglium L. and has been used for the treatment of gastrointestinal disturbance in Asia. It is well known that the main component of CF is croton oil (CO). The present study is to investigate the effects of CF extracts (CFE) and CO on lipolysis in OP9 adipocytes. Methods. Glycerol release to the culture supernatants was used as a marker of adipocyte lipolysis. Results. Treatment with various concentrations of CFE and CO stimulates glycerol release in a dose-dependent manner. The increase in glycerol release by CFE is more potent than isoproterenol, which is a β-adrenergic agonist as a positive control in our system. The increased lipolysis by CFE and CO was accompanied by an increase of phosphorylated hormone sensitive lipase (pHSL) but not nonphosphorylated HSL protein and mRNA. Pretreatment with H89, which is a protein kinase A inhibitor, significantly abolished the CFE- and CO-induced glycerol release in OP9 adipocytes. These results suggest that CFE and CO may be a candidate for the development of a lipolysis-stimulating agent in adipocytes. PMID:25435891

  19. Crotonis Fructus and Its Constituent, Croton Oil, Stimulate Lipolysis in OP9 Adipocytes.

    PubMed

    Kim, Mi-Seong; Kim, Ha-Rim; So, Hong-Seob; Lee, Young-Rae; Moon, Hyoung-Chul; Ryu, Do-Gon; Yang, Sei-Hoon; Lee, Guem-San; Song, Je-Ho; Kwon, Kang-Beom

    2014-01-01

    Introduction. Crotonis fructus (CF) is the mature fruit of Croton tiglium L. and has been used for the treatment of gastrointestinal disturbance in Asia. It is well known that the main component of CF is croton oil (CO). The present study is to investigate the effects of CF extracts (CFE) and CO on lipolysis in OP9 adipocytes. Methods. Glycerol release to the culture supernatants was used as a marker of adipocyte lipolysis. Results. Treatment with various concentrations of CFE and CO stimulates glycerol release in a dose-dependent manner. The increase in glycerol release by CFE is more potent than isoproterenol, which is a β-adrenergic agonist as a positive control in our system. The increased lipolysis by CFE and CO was accompanied by an increase of phosphorylated hormone sensitive lipase (pHSL) but not nonphosphorylated HSL protein and mRNA. Pretreatment with H89, which is a protein kinase A inhibitor, significantly abolished the CFE- and CO-induced glycerol release in OP9 adipocytes. These results suggest that CFE and CO may be a candidate for the development of a lipolysis-stimulating agent in adipocytes.

  20. Neuropeptide B and W regulate leptin and resistin secretion, and stimulate lipolysis in isolated rat adipocytes.

    PubMed

    Skrzypski, Marek; Pruszyńska-Oszmałek, Ewa; Ruciński, Marcin; Szczepankiewicz, Dawid; Sassek, Maciej; Wojciechowicz, Tatiana; Kaczmarek, Przemysław; Kołodziejski, Paweł A; Strowski, Mathias Z; Malendowicz, Ludwik K; Nowak, Krzysztof W

    2012-06-10

    Neuropeptide B (NPB) and W (NPW) regulate food intake and energy homeostasis in humans via two G-protein-coupled receptor subtypes, termed as GPR7 and GPR8. Rodents express GPR7 only. In animals, NPW decreases insulin and leptin levels, whereas the deletion of either NPB or GPR7 leads to obesity and hyperphagia. Metabolic and endocrine in vitro activities of NPW/NPB in adipocytes are unknown. We therefore characterize the effects of NPB and NPW on the secretion and expression of leptin and resistin, and on lipolysis, using rat adipocytes. Isolated rat adipocytes express GPR7 mRNA. NPB and NPW are expressed in macrophages and preadipocytes but are absent in mature adipocytes. Both, NPB and NPW reduce the secretion and expression of leptin from isolated rat adipocytes. NPB stimulates the secretion and expression of resistin, whereas both, NPB and NPW increase lipolysis. Our study demonstrates for the first time that NPB and NPW regulate the expression and secretion of leptin and resistin, and increase lipolysis in isolated rat adipocytes. These effects are presumably mediated via GPR7. The increase of resistin secretion, stimulation of lipolysis and the decrease of leptin secretion may represent mechanisms, through which NPB and NPW can affect glucose and lipid homeostasis, and food intake in rodents. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Partial Inhibition of Adipose Tissue Lipolysis Improves Glucose Metabolism and Insulin Sensitivity Without Alteration of Fat Mass

    PubMed Central

    Girousse, Amandine; Tavernier, Geneviève; Valle, Carine; Moro, Cedric; Mejhert, Niklas; Dinel, Anne-Laure; Houssier, Marianne; Roussel, Balbine; Besse-Patin, Aurèle; Combes, Marion; Mir, Lucile; Monbrun, Laurent; Bézaire, Véronic; Prunet-Marcassus, Bénédicte; Waget, Aurélie; Vila, Isabelle; Caspar-Bauguil, Sylvie; Louche, Katie; Marques, Marie-Adeline; Mairal, Aline; Renoud, Marie-Laure; Galitzky, Jean; Holm, Cecilia; Mouisel, Etienne; Thalamas, Claire; Viguerie, Nathalie; Sulpice, Thierry; Burcelin, Rémy; Arner, Peter; Langin, Dominique

    2013-01-01

    When energy is needed, white adipose tissue (WAT) provides fatty acids (FAs) for use in peripheral tissues via stimulation of fat cell lipolysis. FAs have been postulated to play a critical role in the development of obesity-induced insulin resistance, a major risk factor for diabetes and cardiovascular disease. However, whether and how chronic inhibition of fat mobilization from WAT modulates insulin sensitivity remains elusive. Hormone-sensitive lipase (HSL) participates in the breakdown of WAT triacylglycerol into FAs. HSL haploinsufficiency and treatment with a HSL inhibitor resulted in improvement of insulin tolerance without impact on body weight, fat mass, and WAT inflammation in high-fat-diet–fed mice. In vivo palmitate turnover analysis revealed that blunted lipolytic capacity is associated with diminution in FA uptake and storage in peripheral tissues of obese HSL haploinsufficient mice. The reduction in FA turnover was accompanied by an improvement of glucose metabolism with a shift in respiratory quotient, increase of glucose uptake in WAT and skeletal muscle, and enhancement of de novo lipogenesis and insulin signalling in liver. In human adipocytes, HSL gene silencing led to improved insulin-stimulated glucose uptake, resulting in increased de novo lipogenesis and activation of cognate gene expression. In clinical studies, WAT lipolytic rate was positively and negatively correlated with indexes of insulin resistance and WAT de novo lipogenesis gene expression, respectively. In obese individuals, chronic inhibition of lipolysis resulted in induction of WAT de novo lipogenesis gene expression. Thus, reduction in WAT lipolysis reshapes FA fluxes without increase of fat mass and improves glucose metabolism through cell-autonomous induction of fat cell de novo lipogenesis, which contributes to improved insulin sensitivity. PMID:23431266

  2. Partial inhibition of adipose tissue lipolysis improves glucose metabolism and insulin sensitivity without alteration of fat mass.

    PubMed

    Girousse, Amandine; Tavernier, Geneviève; Valle, Carine; Moro, Cedric; Mejhert, Niklas; Dinel, Anne-Laure; Houssier, Marianne; Roussel, Balbine; Besse-Patin, Aurèle; Combes, Marion; Mir, Lucile; Monbrun, Laurent; Bézaire, Véronic; Prunet-Marcassus, Bénédicte; Waget, Aurélie; Vila, Isabelle; Caspar-Bauguil, Sylvie; Louche, Katie; Marques, Marie-Adeline; Mairal, Aline; Renoud, Marie-Laure; Galitzky, Jean; Holm, Cecilia; Mouisel, Etienne; Thalamas, Claire; Viguerie, Nathalie; Sulpice, Thierry; Burcelin, Rémy; Arner, Peter; Langin, Dominique

    2013-01-01

    When energy is needed, white adipose tissue (WAT) provides fatty acids (FAs) for use in peripheral tissues via stimulation of fat cell lipolysis. FAs have been postulated to play a critical role in the development of obesity-induced insulin resistance, a major risk factor for diabetes and cardiovascular disease. However, whether and how chronic inhibition of fat mobilization from WAT modulates insulin sensitivity remains elusive. Hormone-sensitive lipase (HSL) participates in the breakdown of WAT triacylglycerol into FAs. HSL haploinsufficiency and treatment with a HSL inhibitor resulted in improvement of insulin tolerance without impact on body weight, fat mass, and WAT inflammation in high-fat-diet-fed mice. In vivo palmitate turnover analysis revealed that blunted lipolytic capacity is associated with diminution in FA uptake and storage in peripheral tissues of obese HSL haploinsufficient mice. The reduction in FA turnover was accompanied by an improvement of glucose metabolism with a shift in respiratory quotient, increase of glucose uptake in WAT and skeletal muscle, and enhancement of de novo lipogenesis and insulin signalling in liver. In human adipocytes, HSL gene silencing led to improved insulin-stimulated glucose uptake, resulting in increased de novo lipogenesis and activation of cognate gene expression. In clinical studies, WAT lipolytic rate was positively and negatively correlated with indexes of insulin resistance and WAT de novo lipogenesis gene expression, respectively. In obese individuals, chronic inhibition of lipolysis resulted in induction of WAT de novo lipogenesis gene expression. Thus, reduction in WAT lipolysis reshapes FA fluxes without increase of fat mass and improves glucose metabolism through cell-autonomous induction of fat cell de novo lipogenesis, which contributes to improved insulin sensitivity.

  3. The immunosuppressive agents rapamycin, cyclosporin A and tacrolimus increase lipolysis, inhibit lipid storage and alter expression of genes involved in lipid metabolism in human adipose tissue.

    PubMed

    Pereira, Maria J; Palming, Jenny; Rizell, Magnus; Aureliano, Manuel; Carvalho, Eugénia; Svensson, Maria K; Eriksson, Jan W

    2013-01-30

    Cyclosporin A (CsA), tacrolimus and rapamycin are immunosuppressive agents (IAs) associated with insulin resistance and dyslipidemia, although their molecular effects on lipid metabolism in adipose tissue are unknown. We explored IAs effects on lipolysis, lipid storage and expression of genes involved on lipid metabolism in isolated human adipocytes and/or adipose tissue obtained via subcutaneous and omental fat biopsies. CsA, tacrolimus and rapamycin increased isoproterenol-stimulated lipolysis and inhibited lipid storage by 20-35% and enhanced isoproterenol-stimulated hormone-sensitive lipase Ser552 phosphorylation. Rapamycin also increased basal lipolysis (~20%) and impaired insulin's antilipolytic effect. Rapamycin, down-regulated the gene expression of perilipin, sterol regulatory element-binding protein 1 (SREBP1) and lipin 1, while tacrolimus down-regulated CD36 and aP2 gene expression. All three IAs increased IL-6 gene expression and secretion, but not expression and secretion of TNF-α or adiponectin. These findings suggest that CsA, tacrolimus and rapamycin enhance lipolysis, inhibit lipid storage and expression of lipogenic genes in adipose tissue, which may contribute to the development of dyslipidemia and insulin resistance associated with immunosuppressive therapy. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  4. The C-terminal fibrinogen-like domain of angiopoietin-like 4 stimulates adipose tissue lipolysis and promotes energy expenditure.

    PubMed

    McQueen, Allison E; Kanamaluru, Deepthi; Yan, Kimberly; Gray, Nora E; Wu, Leslie; Li, Mei-Lan; Chang, Anthony; Hasan, Adeeba; Stifler, Daniel; Koliwad, Suneil K; Wang, Jen-Chywan

    2017-09-29

    Angptl4 (Angiopoietin-like 4) is a circulating protein secreted by white and brown adipose tissues and the liver. Structurally, Angptl4 contains an N-terminal coiled-coil domain (CCD) connected to a C-terminal fibrinogen-like domain (FLD) via a cleavable linker, and both full-length Angptl4 and its individual domains circulate in the bloodstream. Angptl4 inhibits extracellular lipoprotein lipase (LPL) activity and stimulates the lipolysis of triacylglycerol stored by adipocytes in the white adipose tissue (WAT). The former activity is furnished by the CCD, but the Angptl4 domain responsible for stimulating adipocyte lipolysis is unknown. We show here that the purified FLD of Angptl4 is sufficient to stimulate lipolysis in mouse primary adipocytes and that increasing circulating FLD levels in mice through adenovirus-mediated overexpression (Ad-FLD) not only induces WAT lipolysis in vivo but also reduces diet-induced obesity without affecting LPL activity. Intriguingly, reduced adiposity in Ad-FLD mice was associated with increased oxygen consumption, fat utilization, and the expression of thermogenic genes (Ucp1 and Ppargc1a) in subcutaneous WAT. Moreover, Ad-FLD mice exhibited increased glucose tolerance. Chronically enhancing WAT lipolysis could produce ectopic steatosis because of an overflow of lipids from the WAT to peripheral tissues; however, this did not occur when Ad-FLD mice were fed a high-fat diet. Rather, these mice had reductions in both circulating triacylglycerol levels and the mRNA levels of lipogenic genes in the liver and skeletal muscle. We conclude that separating the FLD from the CCD-mediated LPL-inhibitory activity of full-length Angptl4 reveals lipolytic and thermogenic properties with therapeutic relevance to obesity and diabetes. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Glycosylphosphatidylinositol-anchored proteins coordinate lipolysis inhibition between large and small adipocytes.

    PubMed

    Müller, Günter; Wied, Susanne; Dearey, Elisabeth-Ann; Biemer-Daub, Gabriele

    2011-07-01

    In response to palmitate, the antidiabetic sulfonylurea drug glimepiride, phosphoinositoglycans, or H(2)O(2), the release of the glycosylphosphatidylinositol-anchored and cyclic adenosine monophosphate-degrading phosphodiesterase Gce1 from adipocytes into small vesicles (adiposomes) and its translocation from adiposomes to cytoplasmic lipid droplets (LD) of adipocytes have been reported. Here the role of Gce1-harboring adiposomes in coordinating lipolysis between differently sized adipocytes was studied. Separate or mixed populations of isolated epididymal rat adipocytes of small and large size and native adipose tissue pieces from young and old rats were incubated with exogenous adiposomes or depleted of endogenous adiposomes and then analyzed for translocation of Gce1 and lipolysis in response to above antilipolytic stimuli. Large compared with small adipocytes are more efficient in releasing Gce1 into adiposomes but less efficient in translocating Gce1 from adiposomes to LDs. Maximal lipolysis inhibition by above antilipolytic stimuli, but not by insulin, was observed with mixed populations of small and large adipocytes (1:1 to 1:2) rather than with separate populations. In mixed adipocyte populations and adipose tissue pieces from young, but not old, rats, lipolysis inhibition by above antilipolytic stimuli, but not by insulin, was dependent on the function of Gce1-harboring adiposomes. Inhibition of lipolysis in rat adipose tissue in response to palmitate, glimepiride, and H(2)O(2) is coordinated via the release of adiposome-associated and glycosylphosphatidylinositol-anchored Gce1 from large "donor" adipocytes and their subsequent translocation to the LDs of small "acceptor" adipocytes. This transfer of antilipolytic information may be of pathophysiologic relevance. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Berberine attenuates cAMP-induced lipolysis via reducing the inhibition of phosphodiesterase in 3T3-L1 adipocytes.

    PubMed

    Zhou, Libin; Wang, Xiao; Yang, Ying; Wu, Ling; Li, Fengying; Zhang, Rong; Yuan, Guoyue; Wang, Ning; Chen, Mingdao; Ning, Guang

    2011-04-01

    Berberine, a hypoglycemic agent, has been shown to decrease plasma free fatty acids (FFAs) level in insulin-resistant rats. In the present study, we explored the mechanism responsible for the antilipolytic effect of berberine in 3T3-L1 adipocytes. It was shown that berberine attenuated lipolysis induced by catecholamines, cAMP-raising agents, and a hydrolyzable cAMP analog, but not by tumor necrosis factor α and a nonhydrolyzable cAMP analog. Unlike insulin, the inhibitory effect of berberine on lipolysis in response to isoproterenol was not abrogated by wortmannin, an inhibitor of phosphatidylinositol 3-kinase, but additive to that of PD98059, an extracellular signal-regulated kinase kinase inhibitor. Prior exposure of adipocytes to berberine decreased the intracellular cAMP production induced by isoproterenol, forskolin, and 3-isobutyl-1-methylxanthine (IBMX), along with hormone-sensitive lipase (HSL) Ser-563 and Ser-660 dephosphorylation, but had no effect on perilipin phosphorylation. Berberine stimulated HSL Ser-565 as well as adenosine monophosphate-activated protein kinase (AMPK) phosphorylation. However, compound C, an AMPK inhibitor, did not reverse the regulatory effect of berberine on HSL Ser-563, Ser-660, and Ser-565 phosphorylation, nor the antilipolytic effect of berberine. Knockdown of AMPK using RNA interference also failed to restore berberine-suppressed lipolysis. cAMP-raising agents increased AMPK activity, which was not additive to that of berberine. Stimulation of adipocytes with berberine increased phosphodiesterase (PDE) 3B and PDE4 activity measured by hydrolysis of (3)[H]cAMP. These results suggest that berberine exerts an antilipolytic effect mainly by reducing the inhibition of PDE, leading to a decrease in cAMP and HSL phosphorylation independent of AMPK pathway.

  7. Curcumin inhibits lipolysis via suppression of ER stress in adipose tissue and prevents hepatic insulin resistance.

    PubMed

    Wang, Lulu; Zhang, Bangling; Huang, Fang; Liu, Baolin; Xie, Yuan

    2016-07-01

    Curcumin is natural polyphenol with beneficial effects on lipid and glucose metabolism and this study aimed to investigate the effects of curcumin on lipolysis and hepatic insulin resistance. Endoplasmic reticulum (ER) stress and lipolysis signaling in adipose and FFA influx, lipid deposits, and glucose production in liver were examined. Palmitate challenge and high-fat diet feeding evoked ER stress-associated lipolysis with cAMP accumulation in adipose tissue. Curcumin treatment inhibited adipose tissue ER stress by dephosphorylation of inositol-requiring enzyme 1α and eukaryotic initiation factor 2α and reduced cAMP accumulation by preserving phosphodiesterase 3B induction. Knockdown of mitogen-activated protein kinase α1/2α with siRNAs diminished such effects of curcumin. As a result from downregulation of cAMP, curcumin blocked protein kinase (PK)A/hormone-sensitive lipase lipolysis signaling, and thereby reduced glycerol and FFA release from adipose tissue. Curcumin reduced FFA influx into the liver by blocking FFA trafficking, and then prevented diacylglycerol deposits and PKCε translocation in the liver, resultantly improving insulin action in the suppression of hepatic gluconeogenesis. Curcumin decreased adipose lipolysis by attenuating ER stress through the cAMP/PKA pathway, reduced FFA influx into the liver by blocking FFA trafficking, and thereby improved insulin sensitivity to inhibit hepatic glucose production. These findings suggested a novel pathway of curcumin to prevent lipid deposits and insulin resistance in liver by beneficial regulation of adipose function. Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.

  8. Colonic fermentation from lactulose inhibits lipolysis in overweight subjects.

    PubMed

    Ferchaud-Roucher, V; Pouteau, E; Piloquet, H; Zaïr, Y; Krempf, M

    2005-10-01

    One of the strategies to prevent insulin resistance is to reduce circulating free fatty acids (FFA). The aim of this study is to assess the effect of an oral lactulose load on fatty acid metabolism in overweight subjects. Eight overweight subjects received a primed constant intravenous infusion of [1-(13)C]acetate and of [1,1,2,3,3-(2)H(5)]glycerol for 9 h. After 3 h of tracer infusion, patients ingested 30 g lactulose, or saline solution. Arterialized blood samples were collected every 20 min. Basal plasma concentrations of acetate were similar before and between oral treatments as well as glycerol and FFA concentrations. Plasma acetate turnover was 11.4 +/- 2.4 vs. 10.7 +/- 1.4 micromol.kg(-1).min(-1) [not significant (NS)], and plasma glycerol turnover was 3.8 +/- 0.4 vs. 4.8 +/- 1.9 micromol.kg(-1).min(-1) (NS). After lactulose ingestion, acetate concentration increased twofold and then decreased to baseline. Acetate turnover rate increased to 15.5 +/- 2.2 micromol.kg(-1).min(-1) after lactulose treatment, whereas it was unchanged after saline treatment (10.3 +/- 2.2 micromol.kg(-1).min(-1), P < or = 0.0001). In contrast, FFA concentrations decreased significantly after lactulose ingestion and then increased slowly. Glycerol turnover decreased after lactulose ingestion compared with saline, 2.8 +/- 0.4 vs. 3.5 +/- 0.3 micromol.kg(-1).min(-1) (P < or = 0.05). A significant negative correlation was found between glycerol and acetate turnover after lactulose treatments (r = -0.78, P < or = 0.02). These results showed in overweight subjects a short-term decrease in FFA level and glycerol turnover after lactulose ingestion related to a decrease of lipolysis in close relationship with an increase of acetate production.

  9. Interleukin-4 regulates lipid metabolism by inhibiting adipogenesis and promoting lipolysis

    PubMed Central

    Tsao, Chang-Hui; Shiau, Ming-Yuh; Chuang, Pei-Hua; Chang, Yih-Hsin; Hwang, Jaulang

    2014-01-01

    Long-term cytokine-mediated inflammation is a risk factor for obesity and type 2 diabetes mellitus (T2DM). Our previous studies reveal significant associations between promoter single nucleotide polymorphisms (SNPs) of interleukin (IL)-4 and T2DM, as well as between SNPs in genes encoding IL-4/IL-4 receptor and high density lipoproteins. Our animal study reveals that IL-4 regulates glucose/lipid metabolism by promoting glucose tolerance and inhibiting lipid deposits. The above results strongly suggest the involvement of IL-4 in energy homeostasis. In the present study, we focus on examining the regulatory mechanism of IL-4 to lipid metabolism. Our results show that IL-4 inhibits adipogenesis by downregulating the expression of peroxisome proliferator-activated receptor-γ and CCAAT/enhancer-binding protein-α. Additionally, IL-4 promotes lipolysis by enhancing the activity and translocation of hormone sensitive lipase (HSL) in mature adipocytes, which suggests that IL-4 plays a pro-lipolytic role in lipid metabolism by boosting HSL activity. Our results demonstrate that IL-4 harbors pro-lipolysis capacity by inhibiting adipocyte differentiation and lipid accumulation as well as by promoting lipolysis in mature adipocytes to decrease lipid deposits. The above findings uncover the novel roles of IL-4 in lipid metabolism and provide new insights into the interactions among cytokine/immune responses, insulin sensitivity, and metabolism. PMID:24347527

  10. Glucocorticoids antagonize tumor necrosis factor-α-stimulated lipolysis and resistance to the antilipolytic effect of insulin in human adipocytes

    PubMed Central

    Fried, Susan K.

    2012-01-01

    High concentrations of TNF within obese adipose tissue increase basal lipolysis and antagonize insulin signaling. Adipocytes of the obese are also exposed to elevated levels of glucocorticoids (GCs), which antagonize TNF actions in many cell types. We tested the hypothesis that TNF decreases sensitivity to the antilipolytic effect of insulin and that GCs antagonize this effect in differentiated human adipocytes. Lipolysis and expression levels of lipolytic proteins were measured after treating adipocytes with TNF, dexamethasone (DEX), or DEX + TNF for up to 48 h. TNF not only increased basal lipolysis, it caused resistance to the antilipolytic effects of insulin in human adipocytes. DEX alone did not significantly affect lipolysis. Cotreatment with DEX blocked TNF induction of basal lipolysis and insulin resistance by antagonizing TNF stimulation of PKA-mediated phosphorylation of hormone-sensitive lipase (HSL) at Ser563 and Ser660 and perilipin. TNF did not affect perilipin, HSL, or phosphodiesterase-3B mass but paradoxically suppressed adipose tissue triglyceride lipase expression, and this effect was blocked by DEX. The extent to which GCs can restrain the lipolytic actions of TNF may both diminish the potentially deleterious effects of excess lipolysis and contribute to fat accumulation in obesity. PMID:22949029

  11. Glucocorticoids antagonize tumor necrosis factor-α-stimulated lipolysis and resistance to the antilipolytic effect of insulin in human adipocytes.

    PubMed

    Lee, Mi-Jeong; Fried, Susan K

    2012-11-01

    High concentrations of TNF within obese adipose tissue increase basal lipolysis and antagonize insulin signaling. Adipocytes of the obese are also exposed to elevated levels of glucocorticoids (GCs), which antagonize TNF actions in many cell types. We tested the hypothesis that TNF decreases sensitivity to the antilipolytic effect of insulin and that GCs antagonize this effect in differentiated human adipocytes. Lipolysis and expression levels of lipolytic proteins were measured after treating adipocytes with TNF, dexamethasone (DEX), or DEX + TNF for up to 48 h. TNF not only increased basal lipolysis, it caused resistance to the antilipolytic effects of insulin in human adipocytes. DEX alone did not significantly affect lipolysis. Cotreatment with DEX blocked TNF induction of basal lipolysis and insulin resistance by antagonizing TNF stimulation of PKA-mediated phosphorylation of hormone-sensitive lipase (HSL) at Ser⁵⁶³ and Ser⁶⁶⁰ and perilipin. TNF did not affect perilipin, HSL, or phosphodiesterase-3B mass but paradoxically suppressed adipose tissue triglyceride lipase expression, and this effect was blocked by DEX. The extent to which GCs can restrain the lipolytic actions of TNF may both diminish the potentially deleterious effects of excess lipolysis and contribute to fat accumulation in obesity.

  12. Artificial sweeteners stimulate adipogenesis and suppress lipolysis independently of sweet taste receptors.

    PubMed

    Simon, Becky R; Parlee, Sebastian D; Learman, Brian S; Mori, Hiroyuki; Scheller, Erica L; Cawthorn, William P; Ning, Xiaomin; Gallagher, Katherine; Tyrberg, Björn; Assadi-Porter, Fariba M; Evans, Charles R; MacDougald, Ormond A

    2013-11-08

    G protein-coupled receptors mediate responses to a myriad of ligands, some of which regulate adipocyte differentiation and metabolism. The sweet taste receptors T1R2 and T1R3 are G protein-coupled receptors that function as carbohydrate sensors in taste buds, gut, and pancreas. Here we report that sweet taste receptors T1R2 and T1R3 are expressed throughout adipogenesis and in adipose tissues. Treatment of mouse and human precursor cells with artificial sweeteners, saccharin and acesulfame potassium, enhanced adipogenesis. Saccharin treatment of 3T3-L1 cells and primary mesenchymal stem cells rapidly stimulated phosphorylation of Akt and downstream targets with functions in adipogenesis such as cAMP-response element-binding protein and FOXO1; however, increased expression of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α was not observed until relatively late in differentiation. Saccharin-stimulated Akt phosphorylation at Thr-308 occurred within 5 min, was phosphatidylinositol 3-kinase-dependent, and occurred in the presence of high concentrations of insulin and dexamethasone; phosphorylation of Ser-473 occurred more gradually. Surprisingly, neither saccharin-stimulated adipogenesis nor Thr-308 phosphorylation was dependent on expression of T1R2 and/or T1R3, although Ser-473 phosphorylation was impaired in T1R2/T1R3 double knock-out precursors. In mature adipocytes, artificial sweetener treatment suppressed lipolysis even in the presence of forskolin, and lipolytic responses were correlated with phosphorylation of hormone-sensitive lipase. Suppression of lipolysis by saccharin in adipocytes was also independent of T1R2 and T1R3. These results suggest that some artificial sweeteners have previously uncharacterized metabolic effects on adipocyte differentiation and metabolism and that effects of artificial sweeteners on adipose tissue biology may be largely independent of the classical sweet taste receptors, T1R2 and T1R3.

  13. Artificial Sweeteners Stimulate Adipogenesis and Suppress Lipolysis Independently of Sweet Taste Receptors*

    PubMed Central

    Simon, Becky R.; Parlee, Sebastian D.; Learman, Brian S.; Mori, Hiroyuki; Scheller, Erica L.; Cawthorn, William P.; Ning, Xiaomin; Gallagher, Katherine; Tyrberg, Björn; Assadi-Porter, Fariba M.; Evans, Charles R.; MacDougald, Ormond A.

    2013-01-01

    G protein-coupled receptors mediate responses to a myriad of ligands, some of which regulate adipocyte differentiation and metabolism. The sweet taste receptors T1R2 and T1R3 are G protein-coupled receptors that function as carbohydrate sensors in taste buds, gut, and pancreas. Here we report that sweet taste receptors T1R2 and T1R3 are expressed throughout adipogenesis and in adipose tissues. Treatment of mouse and human precursor cells with artificial sweeteners, saccharin and acesulfame potassium, enhanced adipogenesis. Saccharin treatment of 3T3-L1 cells and primary mesenchymal stem cells rapidly stimulated phosphorylation of Akt and downstream targets with functions in adipogenesis such as cAMP-response element-binding protein and FOXO1; however, increased expression of peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α was not observed until relatively late in differentiation. Saccharin-stimulated Akt phosphorylation at Thr-308 occurred within 5 min, was phosphatidylinositol 3-kinase-dependent, and occurred in the presence of high concentrations of insulin and dexamethasone; phosphorylation of Ser-473 occurred more gradually. Surprisingly, neither saccharin-stimulated adipogenesis nor Thr-308 phosphorylation was dependent on expression of T1R2 and/or T1R3, although Ser-473 phosphorylation was impaired in T1R2/T1R3 double knock-out precursors. In mature adipocytes, artificial sweetener treatment suppressed lipolysis even in the presence of forskolin, and lipolytic responses were correlated with phosphorylation of hormone-sensitive lipase. Suppression of lipolysis by saccharin in adipocytes was also independent of T1R2 and T1R3. These results suggest that some artificial sweeteners have previously uncharacterized metabolic effects on adipocyte differentiation and metabolism and that effects of artificial sweeteners on adipose tissue biology may be largely independent of the classical sweet taste receptors, T1R2 and T1R3. PMID

  14. Insulin resistance and increased lipolysis in bone marrow derived adipocytes stimulated with agonists of Toll-like receptors.

    PubMed

    Franchini, M; Monnais, E; Seboek, D; Radimerski, T; Zini, E; Kaufmann, K; Lutz, T; Reusch, C; Ackermann, M; Muller, B; Linscheid, P

    2010-09-01

    Our objectives were to identify Toll-like receptors (TLRs) in human bone marrow derived adipocytes, to test specific TLR agonists for their ability to induce a proinflammatory response, and to investigate possible metabolic effects after TLR activation, in particular, those associated with insulin resistance and lipolysis. Mesenchymal stem cells were isolated from human bone marrow and differentiated into adipocytes. Total RNA before or after stimulation with agonists specific for TLR was extracted for analysis of expression of TLRs proinflammatory signals and molecules involved in glucose metabolism (IRS-1 and GLUT4). Furthermore, cytokine protein expression was measured from cell lysates. Finally, insulin induced glucose uptake and lipolysis were measured. Human bone marrow-derived adipocytes express TLR1-10. They react to stimulation with specific ligands with expression of inflammatory markers (IL-1beta, IL-6, TNFalpha, IL-8, MCP-1) at the RNA and protein levels. IRS-1 and GLUT4 expression was downregulated after stimulation with the TLR4 and TLR3 specific ligands LPS and poly (I:C), respectively. Insulin-induced glucose uptake was decreased and lipolysis increased. We conclude that adipocytes express TLR 1-10 and react to agonists specific for TLR 1-6. As a consequence proinflammatory cytokine are induced, in particular, IL-6, IL-8, and MCP-1. Since stimulation is followed by decreased insulin-induced glucose uptake and increased lipolysis we conclude that TLRs may be important linking molecules in the generation of insulin resistance in fat tissue.

  15. Phloretin and phlorizin promote lipolysis and inhibit inflammation in mouse 3T3-L1 cells and in macrophage-adipocyte co-cultures.

    PubMed

    Huang, Wen-Chung; Chang, Wei-Tien; Wu, Shu-Ju; Xu, Pei-Yin; Ting, Nai-Chun; Liou, Chian-Jiun

    2013-10-01

    Previous studies found that phloretin (PT) and phlorizin (PZ) could inhibit glucose transport, with PT being a better inhibitor of lipid peroxidation. This study aimed to evaluate the antiobesity effects of PT and PZ in 3T3-L1 cells and if they can modulate the relationship between adipocytes and macrophages. Differentiated 3T3-L1 cells were treated with PT or PZ. Subsequently, transcription factors of adipogenesis and lipolysis proteins were measured. In addition, RAW 264.7 macrophages treated with PT or PZ were cultured in differentiated media from 3T3-L1 cells to analyze inflammatory mediators and signaling pathways. PT significantly enhanced glycerol release and inhibited the adipogenesis-related transcription factors. PT also promoted phosphorylation of AMP-activated protein kinase and increased activity of adipose triglyceride lipase and hormone-sensitive lipase. PT suppressed the nuclear transcription factor kappa-B and mitogen-activated protein kinase pathways when RAW 264.7 cells were cultured in differentiated media from 3T3-L1 cells. PZ improved lipolysis and inhibited the macrophage inflammatory response less effectively than PT. This study suggests that PT is more effective than PZ at increasing lipolysis in adipocytes. In addition, PT also suppresses inflammatory response in macrophage that is stimulated by differentiated media from 3T3-L1 cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Cardiotrophin-1 stimulates lipolysis through the regulation of main adipose tissue lipases[S

    PubMed Central

    López-Yoldi, Miguel; Fernández-Galilea, Marta; Laiglesia, Laura M.; Larequi, Eduardo; Prieto, Jesús; Martínez, J. Alfredo; Bustos, Matilde; Moreno-Aliaga, Maria J.

    2014-01-01

    Cardiotrophin-1 (CT-1) is a cytokine with antiobesity properties and with a role in lipid metabolism regulation and adipose tissue function. The aim of this study was to analyze the molecular mechanisms involved in the lipolytic actions of CT-1 in adipocytes. Recombinant CT-1 (rCT-1) effects on the main proteins and signaling pathways involved in the regulation of lipolysis were evaluated in 3T3-L1 adipocytes and in mice. rCT-1 treatment stimulated basal glycerol release in a concentration- and time-dependent manner in 3T3-L1 adipocytes. rCT-1 (20 ng/ml for 24 h) raised cAMP levels, and in parallel increased protein kinase (PK)A-mediated phosphorylation of perilipin and hormone sensitive lipase (HSL) at Ser660. siRNA knock-down of HSL or PKA, as well as pretreatment with the PKA inhibitor H89, blunted the CT-1-induced lipolysis, suggesting that the lipolytic action of CT-1 in adipocytes is mainly mediated by activation of HSL through the PKA pathway. In ob/ob mice, acute rCT-1 treatment also promoted PKA-mediated phosphorylation of perilipin and HSL at Ser660 and Ser563, and increased adipose triglyceride lipase (desnutrin) content in adipose tissue. These results showed that the ability of CT-1 to regulate the activity of the main lipases underlies the lipolytic action of this cytokine in vitro and in vivo, and could contribute to CT-1 antiobesity effects. PMID:25351614

  17. Cardiotrophin-1 stimulates lipolysis through the regulation of main adipose tissue lipases.

    PubMed

    López-Yoldi, Miguel; Fernández-Galilea, Marta; Laiglesia, Laura M; Larequi, Eduardo; Prieto, Jesús; Martínez, J Alfredo; Bustos, Matilde; Moreno-Aliaga, Maria J

    2014-12-01

    Cardiotrophin-1 (CT-1) is a cytokine with antiobesity properties and with a role in lipid metabolism regulation and adipose tissue function. The aim of this study was to analyze the molecular mechanisms involved in the lipolytic actions of CT-1 in adipocytes. Recombinant CT-1 (rCT-1) effects on the main proteins and signaling pathways involved in the regulation of lipolysis were evaluated in 3T3-L1 adipocytes and in mice. rCT-1 treatment stimulated basal glycerol release in a concentration- and time-dependent manner in 3T3-L1 adipocytes. rCT-1 (20 ng/ml for 24 h) raised cAMP levels, and in parallel increased protein kinase (PK)A-mediated phosphorylation of perilipin and hormone sensitive lipase (HSL) at Ser660. siRNA knock-down of HSL or PKA, as well as pretreatment with the PKA inhibitor H89, blunted the CT-1-induced lipolysis, suggesting that the lipolytic action of CT-1 in adipocytes is mainly mediated by activation of HSL through the PKA pathway. In ob/ob mice, acute rCT-1 treatment also promoted PKA-mediated phosphorylation of perilipin and HSL at Ser660 and Ser563, and increased adipose triglyceride lipase (desnutrin) content in adipose tissue. These results showed that the ability of CT-1 to regulate the activity of the main lipases underlies the lipolytic action of this cytokine in vitro and in vivo, and could contribute to CT-1 antiobesity effects. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

  18. [Physical lipolysis].

    PubMed

    Steinert, M

    2010-10-01

    The number of non-invasive procedures is steadily growing. Lipolysis with focused ultrasound, cryo-lipolysis, laser-lipolysis, radiofrequency-lipolysis, HIFU-lipolysis, classic liposuction, vibration-assisted liposuction and water beam-assisted Liposuction are newly established procedures to treat diet- and sport resistant fat deposits. Non-invasive lipolysis with focused ultrasound in combination with radiofrequency as well as cryo-lipolysis are the most established procedures. The methods are described in detail and evaluated.

  19. Inhibition of lipolysis by agents acting via adenylate cyclase in fat cells from infants and adults.

    PubMed

    Marcus, C; Sonnenfeld, T; Karpe, B; Bolme, P; Arner, P

    1989-09-01

    The in vitro lipolytic effect of catecholamines is poor during infancy because of enhanced alpha 2-adrenoceptor activity. The mechanisms behind this were investigated in isolated fat cells obtained from 1- to 4-mo-old infants and from adults. The cells were incubated with agents that inhibit lipolysis through distinct receptors coupled to adenylate cyclase via the inhibitory GTP binding coupling protein, Gi. The sensitivity to the alpha 2-adrenoceptor agonist clonidine was 14 times higher in the infant group as compared to the adults, whereas that to an adenosine analogue was 14 times lower. The sensitivities to prostaglandin E2 and nicotinic acid were similar in both age groups. Preincubation of the adipocytes with pertussis toxin abolished the antilipolytic effects of all agents. The density of alpha 2-adrenoceptor binding sites determined with [3H]yohimbine was increased by about 25% in the infants. In conclusion, the antilipolytic sensitivity of adenosine and alpha 2-adrenoceptors develops separately and may play different roles in the regulation of lipolysis in man. Furthermore, the enhanced alpha 2-adrenoceptor sensitivity during infancy seems at least in part to be due to an increase in the number of receptors.

  20. Cellular tolerance to adenosine receptor-mediated inhibition of lipolysis: altered adenosine 3',5'-monophosphate metabolism and protein kinase activation.

    PubMed

    Hoffman, B B; Prokocimer, P; Thomas, J M; Vagelos, R; Chang, H; Reaven, G M

    1989-05-01

    Prolonged exposure of many types of cells to drugs or hormones that inhibit the activity of the enzyme adenylate cyclase, such as narcotics and alpha 2-adrenergic agonists, leads to enhanced accumulation of cAMP upon removal of the inhibitory drug. We have found previously that chronic infusion of the adenosine A1 receptor agonist phenylisopropyladenosine (PIA), an inhibitor of adenylate cyclase, into rats leads to enhanced isoproterenol-stimulated cAMP accumulation in adipocytes isolated from these animals. The enhanced cAMP accumulation was associated with an impaired ability of PIA to inhibit lipolysis in these cells. In the present study we have investigated the mechanism of the enhanced cAMP accumulation in adipocytes from PIA-infused rats and the relationship of these changes to the impaired antilipolytic action of the drug. The enhanced isoproterenol-stimulated cAMP accumulation in adipocytes prepared from PIA-infused rats was due to both an increased rate of cAMP synthesis and a decreased rate of cAMP metabolism at high concentrations of cAMP without a change in phosphodiesterase activity. There was heterologous desensitization of the ability of PIA, prostaglandin E1, and nicotinic acid to inhibit cAMP accumulation in the adipocytes from PIA-infused rats; there was an increase in the EC50 of each of these agonists, although maximal inhibition of cAMP accumulation was similar. The relationship between the activation of cAMP-dependent kinase and extent of lipolysis was similar in the two groups of cells. We demonstrated that the explanation for the impaired ability of PIA to decrease the rate of isoproterenol (10(-7) M)-stimulated lipolysis in the cells from the PIA-infused rats was due to the markedly increased concentrations of cAMP in these cells, which led to sufficient activation of the kinase to maintain a high rate of lipolysis even in the presence of PIA. In addition, we found that the changes induced by the PIA infusion were largely reversible over a

  1. Nutrition Supplements to Stimulate Lipolysis: A Review in Relation to Endurance Exercise Capacity.

    PubMed

    Kim, Jisu; Park, Jonghoon; Lim, Kiwon

    2016-01-01

    Athletes make great efforts to increase their endurance capacity in many ways. Using nutrition supplements for stimulating lipolysis is one such strategy to improve endurance performance. These supplements contain certain ingredients that affect fat metabolism; furthermore, in combination with endurance training, they tend to have additive effects. A large body of scientific evidence shows that nutrition supplements increase fat metabolism; however, the usefulness of lipolytic supplements as ergogenic functional foods remains controversial. The present review will describe the effectiveness of lipolytic supplements in fat metabolism and as an ergogenic aid for increasing endurance exercise capacity. There are a number of lipolytic supplements available on the market, but this review focuses on natural ingredients such as caffeine, green tea extract, L-carnitine, Garcinia cambogia (hydroxycitric acid), capsaicin, ginseng, taurine, silk peptides and octacosanol, all of which have shown scientific evidence of enhancing fat metabolism associated with improving endurance performance. We excluded some other supplements owing to lack of data on fat metabolism or endurance capacity. Based on the data in this review, we suggest that a caffeine and green tea extract improves endurance performance and enhances fat oxidation. Regarding other supplements, the data on their practical implications needs to be gathered, especially for athletes.

  2. Inhibition of Lipolysis by Mercaptoacetate and Etomoxir Specifically Sensitize Drug-Resistant Lung Adenocarcinoma Cell to Paclitaxel

    PubMed Central

    Zhou, Xiang; Zhang, Teng; Zhao, Li; Miao, Ping; Song, Shaoli; Sun, Xiaoguang; Liu, Jianjun; Zhao, Xiaoping; Huang, Gang

    2013-01-01

    Chemoresistance is a major cause of treatment failure in patients with lung cancer. Although the extensive efforts have been made in overcoming chemoresistance, the underlying mechanisms are still elusive. Cancer cells reprogram cellular metabolism to satisfy the demands of malignant phenotype. To reveal roles of cancer metabolism in regulating chemoresistance, we profiled the metabolic characteristics in paclitaxel-resistant lung cancer cells by flux assay. Glucose and oleate metabolism were significantly different between resistant and non-resistant cells. In addition, targeting metabolism as a strategy to overcome drug resistance was investigated using specific metabolic inhibitors. Inhibition of glycolysis and oxidative phosphorylation by 2-deoxyglucose and malonate, respectively, potentiated the effects of paclitaxel on nonresistant lung adenocarcinoma cells but not paclitaxel-resistant cells. By contrast, inhibition of lipolysis by mercaptoacetate or etomoxir synergistically inhibited drug-resistant lung adenocarcinoma cell proliferation. We conclude that lipolysis inhibition potentially be a therapeutic strategy to overcome drug resistance in lung cancer. PMID:24040298

  3. The role of lipolysis stimulated lipoprotein receptor in breast cancer and directing breast cancer cell behavior.

    PubMed

    Reaves, Denise K; Fagan-Solis, Katerina D; Dunphy, Karen; Oliver, Shannon D; Scott, David W; Fleming, Jodie M

    2014-01-01

    The claudin-low molecular subtype of breast cancer is of particular interest for clinically the majority of these tumors are poor prognosis, triple negative, invasive ductal carcinomas. Claudin-low tumors are characterized by cancer stem cell-like features and low expression of cell junction and adhesion proteins. Herein, we sought to define the role of lipolysis stimulated lipoprotein receptor (LSR) in breast cancer and cancer cell behavior as LSR was recently correlated with tumor-initiating features. We show that LSR was expressed in epithelium, endothelium, and stromal cells within the healthy breast tissue, as well as in tumor epithelium. In primary breast tumor bioposies, LSR expression was significantly correlated with invasive ductal carcinomas compared to invasive lobular carcinomas, as well as ERα positive tumors and breast cancer cell lines. LSR levels were significantly reduced in claudin-low breast cancer cell lines and functional studies illustrated that re-introduction of LSR into a claudin-low cell line suppressed the EMT phenotype and reduced individual cell migration. However, our data suggest that LSR may promote collective cell migration. Re-introduction of LSR in claudin-low breast cancer cell lines reestablished tight junction protein expression and correlated with transepithelial electrical resistance, thereby reverting claudin-low lines to other intrinsic molecular subtypes. Moreover, overexpression of LSR altered gene expression of pathways involved in transformation and tumorigenesis as well as enhanced proliferation and survival in anchorage independent conditions, highlighting that reestablishment of LSR signaling promotes aggressive/tumor initiating cell behaviors. Collectively, these data highlight a direct role for LSR in driving aggressive breast cancer behavior.

  4. Liver-Specific Loss of Lipolysis-Stimulated Lipoprotein Receptor Triggers Systemic Hyperlipidemia in Mice

    PubMed Central

    Narvekar, Prachiti; Berriel Diaz, Mauricio; Krones-Herzig, Anja; Hardeland, Ulrike; Strzoda, Daniela; Stöhr, Sigrid; Frohme, Marcus; Herzig, Stephan

    2009-01-01

    OBJECTIVE In mammals, proper storage and distribution of lipids in and between tissues is essential for the maintenance of energy homeostasis. In contrast, aberrantly high levels of triglycerides in the blood (“hypertriglyceridemia”) represent a hallmark of the metabolic syndrome and type 2 diabetes. As hypertriglyceridemia has been identified as an important risk factor for cardiovascular complications, in this study we aimed to identify molecular mechanisms in aberrant triglyceride elevation under these conditions. RESEARCH DESIGN AND METHODS To determine the importance of hepatic lipid handling for systemic dyslipidemia, we profiled the expression patterns of various hepatic lipid transporters and receptors under healthy and type 2 diabetic conditions. A differentially expressed lipoprotein receptor was functionally characterized by generating acute, liver-specific loss- and gain-of-function animal models. RESULTS We show that the hepatic expression of lipid transporter lipolysis-stimulated lipoprotein receptor (LSR) is specifically impaired in mouse models of obesity and type 2 diabetes and can be restored by leptin replacement. Experimental imitation of this pathophysiological situation by liver-specific knockdown of LSR promotes hypertriglyceridemia and elevated apolipoprotein (Apo)B and E serum levels in lean wild-type and ApoE knockout mice. In contrast, genetic restoration of LSR expression in obese animals to wild-type levels improves serum triglyceride levels and serum profiles in these mice. CONCLUSIONS The dysregulation of hepatic LSR under obese and diabetic conditions may provide a molecular rationale for systemic dyslipidemia in type 2 diabetes and the metabolic syndrome and represent a novel target for alternative treatment strategies in these patients. PMID:19188430

  5. Mechanism for desensitization of beta-adrenergic receptor-stimulated lipolysis in adipocytes from rats harboring pheochromocytoma.

    PubMed

    Prokocimer, P G; Maze, M; Vickery, R G; Hoffman, B B

    1988-07-01

    Prolonged stimulation of beta-adrenergic receptors with catecholamines leads to desensitization of their ability to activate cAMP accumulation. However, little is known about the relationship between these changes and possible alterations in physiological responses. We have used isolated adipocytes prepared from NEDH rats harboring pheochromocytomas, a norepinephrine-secreting tumor, to address this question. As expected, there was a decrease in the ability of isoproterenol to maximally activate cAMP accumulation in adipocytes from rat harboring pheochromocytoma [323 +/- 107 vs. 707 +/- 145 pmol/10(5) cells.min (mean +/- SD) in controls]. This change was associated with an increase in the EC50 of isoproterenol for activation of cAMP-dependent protein kinase (5.8 X 10(-8) vs. 2.4 X 10(-8) M in controls) and a decrease in maximal activation of the kinase (38 +/- 16% vs. 77 +/- 14% in controls). For lipolysis there was a loss in sensitivity to isoproterenol but no change in maximal lipolytic rate in the adipocytes from rats harboring pheochromocytoma. For both groups there was a similar relationship between kinase activation and lipolysis; maximal lipolysis had already occurred for protein kinase-A activity ratios less than 30%. Therefore, the blunted cAMP response in adipocytes from rats harboring pheochromocytoma did not impair the maximal lipolytic rate. These results demonstrate that adipocytes can efficiently maintain maximal lipolysis in a desensitized state because of considerable reserve in the biochemical cascade leading to the lipolytic response. In addition, our findings demonstrate that there are no regulatory changes induced by prolonged exposure to catecholamines that are distal to cAMP accumulation.

  6. Insulin alters cAMP-activated lipolysis but not cAMP-inhibited glycogen synthase in permeabilized adipocytes

    SciTech Connect

    Mooney, R.A.; Wisniewski, J.L.

    1986-05-01

    Lipolysis and, to a lesser extent, glycogen synthase activity are regulated in adipocytes by cellular cAMP and counter-regulated by insulin. These activities were measured in situ in digitonin (20 ..mu..g/ml) permeabilized rat adipocytes. Incorporation of /sup 3/H UDP-glucose into endogenous glycogen in the presence of KF, EDTA and 10mM glucose-6-phosphate was the basis of the G.S. assay. Cellular GS activity determined by this technique was 1.4 +/- 0.2 fold greater than that of matched homogenates. Insulin treatment of intact cells prior to permeabilization increased GS activity ratio (-/+ G-6-P) 2.5 fold when subsequently measured by the in situ assay. Following digitonin permeabilization, addition of cAMP to the suspension medium increased lipolysis 7 fold and decreased GS activity ratio to 0.38 +/- 0.01 from a basal value of 0.44 +/- 0.06. ATP had a negligible effect on lipolysis but decreased GS to 0.16 +/- 0.04. ATP plus cAMP was only slightly more effective on GS than ATP alone. Insulin at 10/sup -9/M inhibited cAMP-dependent lipolysis by 27% but had no effect on the cAMP- or ATP-dependent decrease in GS. These results suggest that insulin's counter-regulatory mechanisms on these two cAMP-dependent processes may be different.

  7. Branched Chain Amino Acids Cause Liver Injury in Obese/Diabetic Mice by Promoting Adipocyte Lipolysis and Inhibiting Hepatic Autophagy.

    PubMed

    Zhang, Fuyang; Zhao, Shihao; Yan, Wenjun; Xia, Yunlong; Chen, Xiyao; Wang, Wei; Zhang, Jinglong; Gao, Chao; Peng, Cheng; Yan, Feng; Zhao, Huishou; Lian, Kun; Lee, Yan; Zhang, Ling; Lau, Wayne Bond; Ma, Xinliang; Tao, Ling

    2016-11-01

    The Western meat-rich diet is both high in protein and fat. Although the hazardous effect of a high fat diet (HFD) upon liver structure and function is well recognized, whether the co-presence of high protein intake contributes to, or protects against, HF-induced hepatic injury remains unclear. Increased intake of branched chain amino acids (BCAA, essential amino acids compromising 20% of total protein intake) reduces body weight. However, elevated circulating BCAA is associated with non-alcoholic fatty liver disease and injury. The mechanisms responsible for this quandary remain unknown; the role of BCAA in HF-induced liver injury is unclear. Utilizing HFD or HFD+BCAA models, we demonstrated BCAA supplementation attenuated HFD-induced weight gain, decreased fat mass, activated mammalian target of rapamycin (mTOR), inhibited hepatic lipogenic enzymes, and reduced hepatic triglyceride content. However, BCAA caused significant hepatic damage in HFD mice, evidenced by exacerbated hepatic oxidative stress, increased hepatic apoptosis, and elevated circulation hepatic enzymes. Compared to solely HFD-fed animals, plasma levels of free fatty acids (FFA) in the HFD+BCAA group are significantly further increased, due largely to AMPKα2-mediated adipocyte lipolysis. Lipolysis inhibition normalized plasma FFA levels, and improved insulin sensitivity. Surprisingly, blocking lipolysis failed to abolish BCAA-induced liver injury. Mechanistically, hepatic mTOR activation by BCAA inhibited lipid-induced hepatic autophagy, increased hepatic apoptosis, blocked hepatic FFA/triglyceride conversion, and increased hepatocyte susceptibility to FFA-mediated lipotoxicity. These data demonstrated that BCAA reduces HFD-induced body weight, at the expense of abnormal lipolysis and hyperlipidemia, causing hepatic lipotoxicity. Furthermore, BCAA directly exacerbate hepatic lipotoxicity by reducing lipogenesis and inhibiting autophagy in the hepatocyte.

  8. ER stress in adipocytes inhibits insulin signaling, represses lipolysis, and alters the secretion of adipokines without inhibiting glucose transport.

    PubMed

    Xu, L; Spinas, G A; Niessen, M

    2010-08-01

    The endoplasmic reticulum (ER) is the intra-cellular site, where secreted and membrane proteins are synthesized. ER stress and activation of the unfolded protein response (UPR) contribute to insulin resistance and the development of diabetes in obesity. It was shown previously in hepatocytes that the UPR activates c-jun N-terminal kinase (JNK), which phosphorylates insulin receptor substrate (IRS) proteins on serine residues thereby inhibiting insulin signal transduction. Here we describe how ER stress affects insulin signaling and the biological function of adipocytes. In addition to inhibition of IRS we found that ER stress downregulates the expression of the insulin receptor. Concomitantly, insulin-induced activation of Akt/PKB and of ERK1/2 was strongly inhibited. Ectopic expression of IRS1 or IRS2 strongly counteracted the inhibitory effect of ER stress on insulin signaling while pharmacological inhibition of JNK with SP600125 resulted only in a mild improvement. ER stress decreased the secretion of the adipokines adiponectin and leptin, but strongly increased secretion of IL-6. ER stress inhibited expression and insulin-induced phosphorylation of AS160, reduced lipolysis but did not inhibit glucose transport. Finally, supernatants collected from 3T3-L1 adipocytes undergoing ER stress improved or impaired proliferation when used to condition the culture medium of INS-1E beta-cells dependent on the degree of ER stress. It appears that ER stress in adipocytes might initially lead to changes resembling early prediabetic stages, which at least in part support the regulation of systemic energy homeostasis. Copyright Georg Thieme Verlag KG Stuttgart New York.

  9. Inhibition of gastrointestinal lipolysis by green tea, coffee, and gomchui (Ligularia fischeri) tea polyphenols during simulated digestion.

    PubMed

    Cha, Kwang Hyun; Song, Dae-Geun; Kim, Sang Min; Pan, Cheol-Ho

    2012-07-25

    Green tea, coffee, and gomchui (Ligularia fischeri) tea, which are rich in polyphenols, may exhibit antiobesity effects by inhibiting pancreatic lipase. However, the bioavailability of some polyphenols is poor due to either degradation or absorption difficulties in the gastrointestinal tract, thus making their beneficial effects doubtful. This study was conducted to evaluate the inhibitory effect of three beverages on lipolysis and the contribution of their major polyphenols during simulated digestion. During simulated digestion, gomchui tea was the most potent at inhibiting gastrointestinal lipolysis, whereas green tea was the least potent. The strongest lipase inhibitor among purified major polyphenols was a green tea polyphenol, (-)-epigallocatechin gallate (EGCG, IC(50) = 1.8 ± 0.57 μM), followed by di-O-caffeoylquinic acid isomers (DCQA, IC(50) from 12.7 ± 4.5 to 40.4 ± 2.3 μM), which are gomchui tea polyphenols. However, the stability of DCQA was greater than that of EGCG when subjected to simulated digestion. Taken together, gomchui tea, which has DCQA as the major polyphenol, showed stronger lipolysis inhibitory activity during simulated digestion compared to both green tea and coffee.

  10. Inhibition of Adipogenesis and Induction of Apoptosis and Lipolysis by Stem Bromelain in 3T3-L1 Adipocytes

    PubMed Central

    Dave, Sandeep; Kaur, Naval Jit; Nanduri, Ravikanth; Dkhar, H. Kitdorlang; Kumar, Ashwani; Gupta, Pawan

    2012-01-01

    The phytotherapeutic protein stem bromelain (SBM) is used as an anti-obesity alternative medicine. We show at the cellular level that SBM irreversibly inhibits 3T3-L1 adipocyte differentiation by reducing adipogenic gene expression and induces apoptosis and lipolysis in mature adipocytes. At the molecular level, SBM suppressed adipogenesis by downregulating C/EBPα and PPARγ independent of C/EBPβ gene expression. Moreover, mRNA levels of adipocyte fatty acid-binding protein (ap2), fatty acid synthase (FAS), lipoprotein lipase (LPL), CD36, and acetyl-CoA carboxylase (ACC) were also downregulated by SBM. Additionally, SBM reduced adiponectin expression and secretion. SBM's ability to repress PPARγ expression seems to stem from its ability to inhibit Akt and augment the TNFα pathway. The Akt–TSC2–mTORC1 pathway has recently been described for PPARγ expression in adipocytes. In our experiments, TNFα upregulation compromised cell viability of mature adipocytes (via apoptosis) and induced lipolysis. Lipolytic response was evident by downregulation of anti-lipolytic genes perilipin, phosphodiestersae-3B (PDE3B), and GTP binding protein Giα1, as well as sustained expression of hormone sensitive lipase (HSL). These data indicate that SBM, together with all-trans retinoic-acid (atRA), may be a potent modulator of obesity by repressing the PPARγ-regulated adipogenesis pathway at all stages and by augmenting TNFα-induced lipolysis and apoptosis in mature adipocytes. PMID:22292054

  11. Inhibition of adipogenesis and induction of apoptosis and lipolysis by stem bromelain in 3T3-L1 adipocytes.

    PubMed

    Dave, Sandeep; Kaur, Naval Jit; Nanduri, Ravikanth; Dkhar, H Kitdorlang; Kumar, Ashwani; Gupta, Pawan

    2012-01-01

    The phytotherapeutic protein stem bromelain (SBM) is used as an anti-obesity alternative medicine. We show at the cellular level that SBM irreversibly inhibits 3T3-L1 adipocyte differentiation by reducing adipogenic gene expression and induces apoptosis and lipolysis in mature adipocytes. At the molecular level, SBM suppressed adipogenesis by downregulating C/EBPα and PPARγ independent of C/EBPβ gene expression. Moreover, mRNA levels of adipocyte fatty acid-binding protein (ap2), fatty acid synthase (FAS), lipoprotein lipase (LPL), CD36, and acetyl-CoA carboxylase (ACC) were also downregulated by SBM. Additionally, SBM reduced adiponectin expression and secretion. SBM's ability to repress PPARγ expression seems to stem from its ability to inhibit Akt and augment the TNFα pathway. The Akt-TSC2-mTORC1 pathway has recently been described for PPARγ expression in adipocytes. In our experiments, TNFα upregulation compromised cell viability of mature adipocytes (via apoptosis) and induced lipolysis. Lipolytic response was evident by downregulation of anti-lipolytic genes perilipin, phosphodiestersae-3B (PDE3B), and GTP binding protein G(i)α(1), as well as sustained expression of hormone sensitive lipase (HSL). These data indicate that SBM, together with all-trans retinoic-acid (atRA), may be a potent modulator of obesity by repressing the PPARγ-regulated adipogenesis pathway at all stages and by augmenting TNFα-induced lipolysis and apoptosis in mature adipocytes.

  12. Endothelin-1 stimulates human adipocyte lipolysis through the ET A receptor.

    PubMed

    Eriksson, A K S; van Harmelen, V; Stenson, B M; Aström, G; Wåhlén, K; Laurencikiene, J; Rydén, M

    2009-01-01

    Levels of the vascular peptide endothelin-1 (ET-1) are significantly elevated in obesity. Adipose tissue-derived ET-1 attenuates insulin-mediated antilipolysis in human visceral adipocytes through the activation of the ET receptor B (ET(B)R), thereby linking ET-1 to insulin resistance. Whether ET-1 has direct effects on lipolysis in human adipocytes is not known. Endothelin-1 receptor (ETR) mRNA expression was determined by quantitative PCR in 130 non-obese and obese subjects. ET-1 mRNA in different adipose tissue regions was also assessed. ETR protein expression was analyzed by western blotting in 37 subjects. The effect of ET-1 on lipolysis was assessed in freshly isolated adipocytes and in vitro differentiated adipocytes from human donors. Freshly isolated human adipocytes incubated with different concentrations of ET-1 showed no acute effect on lipolysis. In contrast, a 24 h incubation in primary cultures of human adipocytes resulted in a significant 50% increase in lipolysis. This effect was concentration dependent and could be mimicked by an agonist of the ET(A) receptor but not with a selective ET(B)R agonist. Adipocyte differentiation was not affected by any of the agonists. In subcutaneous (s.c.) adipose tissue from 19 non-obese and 18 obese subjects, the protein expression of ET(A)R was significantly higher in obese subjects whereas there was no difference in ET(B)R expression. Interestingly, the differences in protein expression were not observed at the mRNA level as ET(A)R expression was similar between lean and obese subjects. Long-term but not acute incubation of human adipocytes with ET-1 results in a significant increase in lipolysis. This appears to be mediated through the activation of ET(A)R, demonstrating a yet another receptor-specific effect of ET-1. In addition, the protein expression of ET(A)R is increased in s.c. adipose tissue in obesity, possibly through post-transcriptional mechanisms. An increased effect of ET-1 could be a mechanism

  13. Subcutaneous Adipocyte Lipolysis Contributes to Circulating Lipid Levels.

    PubMed

    Rydén, Mikael; Arner, Peter

    2017-09-01

    Fatty acids released via fat cell lipolysis can affect circulating lipid levels. However, the contribution of different lipolysis measures in adipose tissue is unknown and was presently examined in isolated subcutaneous adipocytes. One thousand and sixty-six men and women were examined for lipolysis regulation in subcutaneous abdominal fat cells. Results were compared with fasting plasma levels of total cholesterol, high-density lipoprotein (HDL) cholesterol (HDL-C) and triglycerides. Spontaneous (basal) lipolysis and the effects of the major hormones stimulating (catecholamines and natriuretic peptides) and inhibiting lipolysis (insulin) were examined. Several statistically significant (P<0.0001) correlations between the different lipolysis parameters and plasma lipids were observed. However, physiologically relevant correlations (adjusted r(2)≥0.05) were only evident between basal or insulin-inhibited lipolysis and plasma triglycerides or HDL-C. Together, these lipolysis measures explained 14% of the variation in triglycerides or HDL-C, respectively. In comparison, a combination of established factors associated with variations in plasma lipids, that is, age; body mass index; waist circumference; waist-to-hip ratio; sex; nicotine use; fat cell volume; and pharmacotherapy against diabetes mellitus; hypertension; or hyperlipidemia explained 17% and 28%, respectively, of the variations in plasma triglycerides and HDL-C. Subcutaneous fat cell lipolysis is an important independent contributor to interindividual variations in plasma lipids. High spontaneous lipolysis activity and resistance to the antilipolytic effect of insulin associate with elevated triglyceride and low HDL-C concentrations. Thus, although several other factors also play a role, subcutaneous adipose tissue may have a causal influence on dyslipidemia. © 2017 The Authors.

  14. Subcutaneous Adipocyte Lipolysis Contributes to Circulating Lipid Levels

    PubMed Central

    2017-01-01

    Objective— Fatty acids released via fat cell lipolysis can affect circulating lipid levels. However, the contribution of different lipolysis measures in adipose tissue is unknown and was presently examined in isolated subcutaneous adipocytes. Approach and Results— One thousand and sixty-six men and women were examined for lipolysis regulation in subcutaneous abdominal fat cells. Results were compared with fasting plasma levels of total cholesterol, high-density lipoprotein (HDL) cholesterol (HDL-C) and triglycerides. Spontaneous (basal) lipolysis and the effects of the major hormones stimulating (catecholamines and natriuretic peptides) and inhibiting lipolysis (insulin) were examined. Several statistically significant (P<0.0001) correlations between the different lipolysis parameters and plasma lipids were observed. However, physiologically relevant correlations (adjusted r2≥0.05) were only evident between basal or insulin-inhibited lipolysis and plasma triglycerides or HDL-C. Together, these lipolysis measures explained 14% of the variation in triglycerides or HDL-C, respectively. In comparison, a combination of established factors associated with variations in plasma lipids, that is, age; body mass index; waist circumference; waist-to-hip ratio; sex; nicotine use; fat cell volume; and pharmacotherapy against diabetes mellitus; hypertension; or hyperlipidemia explained 17% and 28%, respectively, of the variations in plasma triglycerides and HDL-C. Conclusions— Subcutaneous fat cell lipolysis is an important independent contributor to interindividual variations in plasma lipids. High spontaneous lipolysis activity and resistance to the antilipolytic effect of insulin associate with elevated triglyceride and low HDL-C concentrations. Thus, although several other factors also play a role, subcutaneous adipose tissue may have a causal influence on dyslipidemia. PMID:28663255

  15. Hydroxytyrosol stimulates lipolysis via A-kinase and extracellular signal-regulated kinase activation in 3T3-L1 adipocytes.

    PubMed

    Drira, Riadh; Sakamoto, Kazuichi

    2014-04-01

    The principal function of the adipose tissue is the storage of energy in the form of triglyceride through the process of adipogenesis, as well as the provision of the stored energy through lipolysis. In the present study, we investigated the effect of hydroxytyrosol on lipolysis in 3T3-L1 adipocytes. 3T3-L1 adipocytes, used as in vitro model in this study, were treated with several concentration of hydroxytyrosol. Glycerol release was measured to identify the lipolytic rate activation. All factors activation and expression were carried out via Western blotting and qRT-PCR. Our results showed that hydroxytyrosol, over a range of concentrations, attenuated triglyceride accumulation and stimulated glycerol release in fully differentiated adipocytes in a dose- and time-dependent manner. Moreover, hydroxytyrosol had no effect on adipocyte viability. To understand the mechanism underlying hydroxytyrosol-stimulated lipolysis, we used inhibitors of PKA, PKC, PKG, ERK1/2, and nitric oxide production. Pretreatment with a PKA inhibitor (Rp-cAMPs) and an ERK1/2 inhibitor (U0126) significantly attenuated hydroxytyrosol-stimulated lipolysis. In contrast, a PKC inhibitor (Calphostin C), 2 PKG inhibitors (KT 5823 and Rp-cGMPs), and a nitric oxide inhibitor (S-ethyl ITU) had no effect on hydroxytyrosol-stimulated lipolysis. Over the same range of concentrations, hydroxytyrosol downregulated the expression of adipose triglyceride lipase, hormone sensitive lipase (HSL), and adipogenesis-related transcription factors PPARγ and C/EBPα. In addition, hydroxytyrosol increased the phosphorylation rate of HSL at Ser563 and Ser660, as well as perilipin and ERK phosphorylation. Hydroxytyrosol induced lipolysis in 3T3-L1 adipocytes via the activation of PKA and ERK1/2 pathway.

  16. On the suppression of plasma nonesterified fatty acids by insulin during enhanced intravascular lipolysis in humans.

    PubMed

    Carpentier, André C; Frisch, Frédérique; Cyr, Denis; Généreux, Philippe; Patterson, Bruce W; Giguère, Robert; Baillargeon, Jean-Patrice

    2005-11-01

    During the fasting state, insulin reduces nonesterified fatty acid (NEFA) appearance in the systemic circulation mostly by suppressing intracellular lipolysis in the adipose tissue. In the postprandial state, insulin may also control NEFA appearance through enhanced trapping into the adipose tissue of NEFA derived from intravascular triglyceride lipolysis. To determine the contribution of suppression of intracellular lipolysis in the modulation of plasma NEFA metabolism by insulin during enhanced intravascular triglyceride lipolysis, 10 healthy nonobese subjects underwent pancreatic clamps at fasting vs. high physiological insulin level with intravenous infusion of heparin plus Intralipid. Nicotinic acid was administered orally during the last 2 h of each 4-h clamp to inhibit intracellular lipolysis and assess insulin's effect on plasma NEFA metabolism independently of its effect on intracellular lipolysis. Stable isotope tracers of palmitate, acetate, and glycerol were used to assess plasma NEFA metabolism and total triglyceride lipolysis in each participant. The glycerol appearance rate was similar during fasting vs. high insulin level, but plasma NEFA levels were significantly lowered by insulin. Nicotinic acid significantly blunted the insulin-mediated suppression of plasma palmitate appearance and oxidation rates by approximately 60 and approximately 70%, respectively. In contrast, nicotinic acid did not affect the marked stimulation of palmitate clearance by insulin. Thus most of the insulin-mediated reduction of plasma NEFA appearance and oxidation can be explained by suppression of intracellular lipolysis during enhanced intravascular triglyceride lipolysis in healthy humans. Our results also suggest that insulin may affect plasma NEFA clearance independently of the suppression of intracellular lipolysis.

  17. Inhibition of Lipolysis Ameliorates Diabetic Phenotype in a Mouse Model of Obstructive Sleep Apnea.

    PubMed

    Weiszenstein, Martin; Shimoda, Larissa A; Koc, Michal; Seda, Ondrej; Polak, Jan

    2016-08-01

    Obstructive sleep apnea (OSA) is associated with insulin resistance, glucose intolerance, and type 2 diabetes. Causal mechanisms mediating this association are not well defined; however, augmented lipolysis in adipose might be involved. Here, we investigated the effect of acipimox treatment (lipolysis inhibitor) on glucose tolerance and insulin sensitivity in mice exposed to intermittent hypoxia (IH). C57BL6/J mice were exposed for 14 days to IH or control conditions. IH was created by decreasing the fraction of inspired oxygen from 20.9 to 6.5%, 60 times/h. Control exposure was air (fraction of inspired oxygen, 20.9%) delivered at an identical flow rate. Acipimox was provided in drinking water (0.5 g/ml) during exposures. After exposures, intraperitoneal insulin (0.5 IU/kg) and glucose (1 g/kg) tolerance tests were performed, and primary adipocytes were isolated for lipolysis experiments. IH elevated fasting glucose by 51% and worsened glucose tolerance and insulin sensitivity by 33 and 102%, respectively. In parallel, IH increased spontaneous lipolysis by 264%, and reduced epididymal fat mass by 15% and adipocyte size by 8%. Acipimox treatment prevented IH-induced lipolysis and increased epididymal fat mass and adipocyte size by 19 and 10%, respectively. Acipimox fully prevented IH-induced impairments in fasting glycemia, glucose tolerance, and insulin sensitivity. For all reported results, P less than 0.05 was considered significant. Augmented lipolysis contributes to insulin resistance and glucose intolerance observed in mice exposed to IH. Acipimox treatment ameliorated the metabolic consequences of IH and might represent a novel treatment option for patients with obstructive sleep apnea.

  18. ApoB100-LDL Acts as a Metabolic Signal from Liver to Peripheral Fat Causing Inhibition of Lipolysis in Adipocytes

    PubMed Central

    Skogsberg, Josefin; Dicker, Andrea; Rydén, Mikael; Åström, Gaby; Nilsson, Roland; Bhuiyan, Hasanuzzaman; Vitols, Sigurd; Mairal, Aline; Langin, Dominique; Alberts, Peteris; Walum, Erik; Tegnér, Jesper; Hamsten, Anders; Arner, Peter; Björkegren, Johan

    2008-01-01

    Background Free fatty acids released from adipose tissue affect the synthesis of apolipoprotein B-containing lipoproteins and glucose metabolism in the liver. Whether there also exists a reciprocal metabolic arm affecting energy metabolism in white adipose tissue is unknown. Methods and Findings We investigated the effects of apoB-containing lipoproteins on catecholamine-induced lipolysis in adipocytes from subcutaneous fat cells of obese but otherwise healthy men, fat pads from mice with plasma lipoproteins containing high or intermediate levels of apoB100 or no apoB100, primary cultured adipocytes, and 3T3-L1 cells. In subcutaneous fat cells, the rate of lipolysis was inversely related to plasma apoB levels. In human primary adipocytes, LDL inhibited lipolysis in a concentration-dependent fashion. In contrast, VLDL had no effect. Lipolysis was increased in fat pads from mice lacking plasma apoB100, reduced in apoB100-only mice, and intermediate in wild-type mice. Mice lacking apoB100 also had higher oxygen consumption and lipid oxidation. In 3T3-L1 cells, apoB100-containing lipoproteins inhibited lipolysis in a dose-dependent fashion, but lipoproteins containing apoB48 had no effect. ApoB100-LDL mediated inhibition of lipolysis was abolished in fat pads of mice deficient in the LDL receptor (Ldlr−/−Apob100/100). Conclusions Our results show that the binding of apoB100-LDL to adipocytes via the LDL receptor inhibits intracellular noradrenaline-induced lipolysis in adipocytes. Thus, apoB100-LDL is a novel signaling molecule from the liver to peripheral fat deposits that may be an important link between atherogenic dyslipidemias and facets of the metabolic syndrome. PMID:19020660

  19. Rosmarinic acid suppresses adipogenesis, lipolysis in 3T3-L1 adipocytes, lipopolysaccharide-stimulated tumor necrosis factor-α secretion in macrophages, and inflammatory mediators in 3T3-L1 adipocytes.

    PubMed

    Rui, Yehua; Tong, Lingxia; Cheng, Jinbo; Wang, Guiping; Qin, Liqiang; Wan, Zhongxiao

    2017-01-01

    Background: Rosmarinic acid (RA) is a natural phenol carboxylic acid with many promising biological effects. It may be a suitable candidate for improving obesity-related adipose tissue dysfunction. Objective: We aimed to investigate the therapeutic use of RA as an anti-obesity agent by measuring its effects on adipogenesis, lipolysis, and messenger RNA (mRNA) expression of major adipokines in 3T3-L1 adipocytes; and its effects on lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) secretion in macrophages and inflammatory mediators in 3T3-L1 adipocytes incubated with macrophage-conditioned medium (MCM). Methods: 3T3-L1 preadipocytes were used to explore how RA affects adipogenesis, as well as the involvement of phosphorylated extracellular signal-regulated kinase-1/2 (p-ERK1/2) and mothers against decapentaplegic homolog 3 (p-Smad3). 3T3-L1 preadipocytes were also differentiated into mature adipocytes to explore how RA affects basal and isoproterenol- and forskolin-stimulated lipolysis; and how RA affects key adipokines' mRNA expression. RAW 264.7 macrophages were stimulated with LPS in the absence or presence of RA to explore RA's effects on TNF-α secretion. MCM was collected and 3T3-L1 adipocytes were incubated with MCM to explore RA's effects on interleukin-6 (IL-6), IL-1β, monocyte chemoattractant protein-1 (MCP-1), and RANTES mRNA expression. Results: During the preadipocyte differentiation process, RA suppressed peroxisome proliferator-activated receptor-γ and CCAAT/enhancer binding protein-α, and activated p-ERK1/2 and p-Smad3; inhibition of adipogenesis by RA was partially restored following treatment with p-ERK1/2 and p-Smad3 inhibitors. In mature adipocytes, RA inhibited basal lipolysis; phosphodiesterase-3 inhibitor reversed this. RA also inhibited isoproterenol- and forskolin-stimulated glycerol and free fatty acid release, and the phosphorylation of hormone-sensitive lipase and perilipin. RA had no effects on leptin, adiponectin

  20. Almond Skin Polyphenol Extract Inhibits Inflammation and Promotes Lipolysis in Differentiated 3T3-L1 Adipocytes.

    PubMed

    Huang, Wen-Chung; Chen, Chi-Yuan; Wu, Shu-Ju

    2017-02-01

    Studies have shown that polyphenols reduce the risk of inflammation-related diseases and upregulates energy expenditure in adipose tissue. Here, we investigated the mechanism of the anti-inflammatory and antiobesity effects of almond skin polyphenol extract (ASP) in differentiated 3T3-L1 adipocytes. The antioxidant effects of ASP were measured based on DPPH radical scavenging activity, Trolox equivalent antioxidant capacity, and total phenolic content. Differentiated 3T3-L1 cells were treated with ASP. Subsequently, lipolysis proteins and transcription factors of adipogenesis were measured. The proinflammatory mediators monocyte chemotactic protein-1 (MCP-1) and chemokine ligand 5 (CCL-5) were determined by enzyme-linked immunosorbent assay. We found that ASP significantly promoted phosphorylation of AMP-activated protein kinase (AMPK), increased activity of adipose triglyceride lipase and hormone-sensitive lipase, and inhibited adipogenesis-related transcription factors. In addition, ASP inhibited the tumor necrosis factor-α (TNF-α)-induced cell inflammatory response via downregulation of MCP-1 and CCL-5 secretion. This study suggests that ASP regulates lipolysis through activation of AMPK, reduced adipogenesis, and suppresses proinflammatory cytokines in adipocytes.

  1. Leptin induces nitric oxide-mediated inhibition of lipolysis and glyceroneogenesis in rat white adipose tissue.

    PubMed

    Niang, Fatoumata; Benelli, Chantal; Ribière, Catherine; Collinet, Martine; Mehebik-Mojaat, Nadia; Penot, Graziella; Forest, Claude; Jaubert, Anne-Marie

    2011-01-01

    Leptin is secreted by white adipose tissue (WAT) and induces lipolysis and nonesterified fatty acid (NEFA) oxidation. During lipolysis, NEFA efflux is the result of triglyceride breakdown, NEFA oxidation, and re-esterification via glyceroneogenesis. Leptin's effects on glyceroneogenesis remain unexplored. We investigated the effect of a long-term treatment with leptin at a physiological concentration (10 μg/L) on lipolysis and glyceroneogenesis in WAT explants and analyzed the underlying mechanisms. Exposure of rat WAT explants to leptin for 2 h resulted in increased NEFA and glycerol efflux. However, a longer treatment with leptin (18 h) did not affect NEFA release and reduced glycerol output. RT-qPCR showed that leptin significantly downregulated the hormone-sensitive lipase (HSL), cytosolic phosphoenolpyruvate carboxykinase (Pck1), and PPARγ genes. In agreement with its effect on mRNA, leptin also decreased the levels of PEPCK-C and HSL proteins. Glyceroneogenesis, monitored by [1-(14) C] pyruvate incorporation into lipids, was reduced. Because leptin increases nitric oxide (NO) production in adipocytes, we explored the role of NO in the leptin signaling pathway. Pretreatment of explants with the NO synthase inhibitor Nω-nitro-l-arginine methyl ester eliminated the effect of leptin on lipolysis, glyceroneogenesis, and expression of the HSL, Pck1, and PPARγ genes. The NO donor S-nitroso-N-acetyl-DL penicillamine mimicked leptin effects, thus demonstrating the role of NO in these pathways. The inverse time-dependent action of leptin on WAT is consistent with a process that limits NEFA re-esterification and energy storage while reducing glycerol release, thus preventing hypertriglyceridemia.

  2. The effect of inhibition of endoplasmic reticulum stress on lipolysis in white adipose tissue in a rat model of chronic kidney disease

    PubMed Central

    Zhu, Yan; Chen, Yu-ling; Li, Cong; Ding, Xiao-yan; Xu, Guo-yu; Hu, Li-li; Hou, Fan-fan; Zhou, Qiu-gen

    2014-01-01

    Aim: Lipolysis in fat tissue plays an important role in the development of metabolic disturbances, a characteristic feature of chronic kidney disease (CKD). In the present study, we tested the hypothesis that the inhibition of endoplasmic reticulum (ER) stress could alleviate lipolysis in white adipose tissue in a rat model of CKD. Methods: A rat model of CKD was established by a method of reduced renal mass (RRM). Lipolysis was measured as the release of glycerol in ex vivo fat pads and cultured primary adipocytes. The activity of lipases and markers of ER stress were measured by Western blotting and immunoprecipitation. Results: Our data showed that lipolysis in visceral white adipose tissue was increased in RRM rats compared with control rats. In addition, increased phosphorylation of hormone-sensitive lipase (HSL) and binding of adipose triglyceride lipase (ATGL) to comparative gene identification-58 (CGI-58) protein were observed in the RRM rats. The phosphorylation of ER stress markers, including IRE1α, PERK, and eukaryotic initiation factor (eIF) 2α, and the expression of ER stress marker 78 kDa glucose-regulated protein (GRP78) were significantly increased in RRM rats. Treatment with an inhibitor of ER stress partially but significantly alleviated lipolysis, and this alleviation was accompanied by reduced binding of ATGL to CGI-58. Conclusion: Our results showed that enhanced lipolysis and ER stress occurred in visceral white adipose tissue in a rat model of CKD. Moreover, inhibition of ER stress significantly alleviated lipolysis. These findings suggest that ER stress is a potential therapeutic target for the metabolic disturbances associated with CKD. PMID:24442147

  3. The effect of inhibition of endoplasmic reticulum stress on lipolysis in white adipose tissue in a rat model of chronic kidney disease.

    PubMed

    Zhu, Yan; Chen, Yu-ling; Li, Cong; Ding, Xiao-yan; Xu, Guo-yu; Hu, Li-li; Hou, Fan-fan; Zhou, Qiu-gen

    2014-03-01

    Lipolysis in fat tissue plays an important role in the development of metabolic disturbances, a characteristic feature of chronic kidney disease (CKD). In the present study, we tested the hypothesis that the inhibition of endoplasmic reticulum (ER) stress could alleviate lipolysis in white adipose tissue in a rat model of CKD. A rat model of CKD was established by a method of reduced renal mass (RRM). Lipolysis was measured as the release of glycerol in ex vivo fat pads and cultured primary adipocytes. The activity of lipases and markers of ER stress were measured by Western blotting and immunoprecipitation. Our data showed that lipolysis in visceral white adipose tissue was increased in RRM rats compared with control rats. In addition, increased phosphorylation of hormone-sensitive lipase (HSL) and binding of adipose triglyceride lipase (ATGL) to comparative gene identification-58 (CGI-58) protein were observed in the RRM rats. The phosphorylation of ER stress markers, including IRE1α, PERK, and eukaryotic initiation factor (eIF) 2α, and the expression of ER stress marker 78 kDa glucose-regulated protein (GRP78) were significantly increased in RRM rats. Treatment with an inhibitor of ER stress partially but significantly alleviated lipolysis, and this alleviation was accompanied by reduced binding of ATGL to CGI-58. Our results showed that enhanced lipolysis and ER stress occurred in visceral white adipose tissue in a rat model of CKD. Moreover, inhibition of ER stress significantly alleviated lipolysis. These findings suggest that ER stress is a potential therapeutic target for the metabolic disturbances associated with CKD.

  4. Adrenergic mechanisms contribute to the late phase of hypoglycemic glucose counterregulation in humans by stimulating lipolysis.

    PubMed Central

    Fanelli, C G; De Feo, P; Porcellati, F; Perriello, G; Torlone, E; Santeusanio, F; Brunetti, P; Bolli, G B

    1992-01-01

    Three studies were performed on nine normal volunteers to assess whether catecholamine-mediated lipolysis contributes to counterregulation to hypoglycemia. In these three studies, insulin was intravenously infused for 8 h (0.30 mU.kg-1.min-1 from 0 to 180 min, and 0.40 mU.kg-1.min-1 until 480 min). In study I (control study), only insulin was infused; in study II (direct + indirect effects of catecholamines), propranolol and phentolamine were superimposed to insulin and exogenous glucose was infused to reproduce the same plasma glucose (PG) concentration of study I. Study III (indirect effect of catecholamines) was the same as study II, except heparin (0.2 U.kg-1.min-1 after 80 min), 10% Intralipid (1 ml.min-1 after 160 min) and variable glucose to match PG of study II, were also infused. Glucose production (HGO), glucose utilization (Rd) [3-3H]glucose, and glucose oxidation and lipid oxidation (LO) (indirect calorimetry) were determined. In all three studies, PG decreased from approximately 4.8 to approximately 2.9 mmol/liter (P = NS between studies), and plasma glycerol and FFA decreased to a nadir at 120 min. Afterwards, in study I plasma glycerol and FFA increased by approximately 75% at 480 min, but in study II they remained approximately 40% lower than in study I, whereas in study III they rebounded as in study I (P = NS). In study II, LO was lower than in study I (1.69 +/- 0.13 vs. 3.53 +/- 0.19 mumol.kg-1.min-1, P less than 0.05); HGO was also lower between 60 and 480 min (7.48 +/- 0.57 vs. 11.6 +/- 0.35 mumol.kg-1.min-1, P less than 0.05), whereas Rd was greater between 210 and 480 min (19 +/- 0.38 vs. 11.4 +/- 0.34 mumol.kg-1.min-1, respectively, P less than 0.05). In study III, LO increased to the values of study I; between 4 and 8 h, HGO increased by approximately 2.5 mumol.kg-1.min-1, and Rd decreased by approximately 7 mumol.kg-1.min-1 vs. study II. We conclude that, in a late phase of hypoglycemia, the indirect effects of catecholamines (lipolysis

  5. Photoactivation of Dok1/ERK/PPARγ signaling axis inhibits excessive lipolysis in insulin-resistant adipocytes.

    PubMed

    Jiang, Xiaoxiao; Huang, Lei; Xing, Da

    2015-07-01

    Insulin resistance is a hallmark of the metabolic syndrome and type 2 diabetes. Increased plasma FFA level is an important cause of obesity-associated insulin resistance. Over-activated ERK is closely related with FFA release from adipose tissues in patients with type 2 diabetes. Nevertheless, there are no effective strategies to lower plasma FFA level. Low-power laser irradiation (LPLI) has been reported to regulate multiple biological processes. However, whether LPLI could ameliorate metabolic disorders and the molecular mechanisms involved remain unknown. In this study, we first demonstrated that LPLI suppresses excessive lipolysis of insulin-resistant adipocytes by activating tyrosine kinases-1(Dok1)/ERK/PPARγ pathway. Our data showed that LPLI inhibits ERK phosphorylation through the activation of Dok1, resulting in decreased phospho-PPARγ level. Non-phosphorylated PPARγ maintains in nucleus to promote the expression of adipogenic genes, reversing excessive lipolysis in insulin-resistant adipocytes. In summary, the present research highlights the important roles of Dok1/ERK/PPARγ pathway in lowering FFA release from adipocytes, and our research extends the knowledge of the biological effects induced by LPLI. Copyright © 2015. Published by Elsevier Inc.

  6. Plin5 alleviates myocardial ischaemia/reperfusion injury by reducing oxidative stress through inhibiting the lipolysis of lipid droplets

    PubMed Central

    Zheng, Pengfei; Xie, Zhonglin; Yuan, Yuan; Sui, Wen; Wang, Chao; Gao, Xing; Zhao, Yuanlin; Zhang, Feng; Gu, Yu; Hu, Peizhen; Ye, Jing; Feng, Xuyang; Zhang, Lijun

    2017-01-01

    Myocardial ischaemia-reperfusion (I/R) injury is a complex pathophysiological process. Current research has suggested that energy metabolism disorders, of which the abnormal consumption of fatty acids is closely related, compose the main pathological basis for myocardial I/R injury. Lipid droplets (LD) are critical regulators of lipid metabolism by LD-associated proteins. Among the lipid droplet proteins, the perilipin family members regulate lipolysis and lipogenesis through different mechanisms. Plin5, an important perilipin protein, promotes LD generation and lowers fatty acid oxidation, thus protecting the myocardium from lipotoxicity. This study investigated the protective effects of Plin5 in I/R myocardium. Our results indicated that Plin5 deficiency exacerbated the myocardial infarct area, aggravated left ventricular systolic dysfunction, reduced lipid storage, and elevated free fatty acids. Plin5-deficient myocardium exhibited severely damaged mitochondria, elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels, and decreased superoxide dismutase (SOD) activity. Furthermore, the decreased phosphorylation of PI3K/Akt in Plin5-null cardiomyocytes might contribute to I/R injury aggravation. In conclusion, Plin5, a new regulator of myocardial lipid metabolism, decreases free fatty acid peroxidation by inhibiting the lipolysis of intracellular lipid droplets, thus providing cardioprotection against I/R injury and shedding new light on therapeutic solutions for I/R diseases. PMID:28218306

  7. In vitro TNF-α- and noradrenaline-stimulated lipolysis is impaired in adipocytes from growing rats fed a low-protein, high-carbohydrate diet.

    PubMed

    Feres, Daniel D S; Dos Santos, Maísa P; Buzelle, Samyra L; Pereira, Mayara P; de França, Suélem A; Garófalo, Maria A R; Andrade, Cláudia M B; Froelich, Mendalli; de Almeida, Fhelipe J S; Frasson, Danúbia; Chaves, Valéria E; Kawashita, Nair H

    2013-08-01

    The aim of this study was to investigate tumor necrosis factor alpha (TNF-α)- and noradrenaline (NE)-stimulated lipolysis in retroperitoneal (RWAT) and epididymal (EAT) white adipose tissue as a means of understanding how low-protein, high-carbohydrate (LPHC) diet-fed rats maintain their lipid storage in a catabolic environment (marked by increases in serum TNF-α and corticosterone and sympathetic flux to RWAT and EAT), as previously observed. Adipocytes or tissues from the RWAT and EAT of rats fed an LPHC diet and rats fed a control (C) diet for 15 days were used in the experiments. The adipocytes from both tissues of the LPHC rats exhibited lower TNF-α- stimulated lipolysis compared to adipocytes from the C rats. The intracellular lipolytic agents IBMX, DBcAMPc and FSK increased lipolysis in both tissues from rats fed the C and LPHC diets compared to basal lipolysis; however, the effect was approximately 2.5-fold lower in adipocytes from LPHC rats. The LPHC diet induced a marked reduction in the β3 and α2-AR, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) content in RWAT and EAT. The LPHC diet did not affect TNF-α receptor 1 content but did induce a reduction in ERK p44/42 in both tissues. The present work indicates that RWAT and EAT from LPHC rats have an impairment in the lipolysis signaling pathway activated by NE and TNF-α, and this impairment explains the reduced response to these lipolytic stimuli, which may be fundamental to the maintenance of lipid storage in LPHC rats.

  8. Positive effects of Forskolin (stimulator of lipolysis) treatment on cryosurvival of in vitro matured porcine oocytes.

    PubMed

    Fu, Xiang-Wei; Wu, Guo-Quan; Li, Jun-Jie; Hou, Yun-Peng; Zhou, Guang-Bin; Lun-Suo; Wang, Yan-Ping; Zhu, Shi-En

    2011-01-15

    In order to examine its effect on oocyte lipid content and cryosurvival, Forskolin was added to the medium for in vitro maturation of porcine oocytes. Treatments were control (IVM without Forskolin during the 42 h incubation period), addition of 10 μM Forskolin for the entire 42 h (0-42) and addition of 10 μM Forskolin between 24 and 42 h only (24-42). In Experiment 1, treatments did not differ significantly in cleavage rate, but the blastocyst formation rate was lower in the 0-42 group than for control and 24-42 group oocytes (17, 32 and 40%, respectively; P < 0.05). It was shown in Experiment 2 that Forskolin treatment from 0-42 h and from 24-42 h significantly reduced lipid content of oocytes compared to that of control cells (65 and 99 vs. 140 μm(2) intensity of fluorescence, respectively; P < 0.05). In Experiment 3, the percentage of oocyte survival after cryopreservation and thawing was significantly higher in both Forskolin treatment groups than in control oocytes (72% for 0-42, 65% for 24-42 and 52% for control; P < 0.05). However, Forskolin treatment did not increase cleavage rates of vitrified in vitro matured porcine oocytes (Control group 28%, 0-42 h group 0%, 24-42 h group 26.67%). Addition of Forskolin affected the nuclear maturation of porcine oocytes. The percentage of PBE (polar body extrusion) were significantly reduced in the 0-42 h group (0-42 h group 42.00 ± 2.08 vs. Control group 79.70 ± 2.82 and 24-42 h group 70.60 ± 2.83; P < 0.05). The 24-42 h group showed similar nuclear status to that of the Control group. We propose that delipation engendered by incubation with 10 μM Forskolin during 24-42 hours of maturation increased cryosurvival of in vitro-maturated porcine oocytes and that attendant chemical lipolysis did not impair their further development as it may have done in oocytes incubated with Forskolin for the full 42 h.

  9. Neural innervation of white adipose tissue and the control of lipolysis.

    PubMed

    Bartness, Timothy J; Liu, Yang; Shrestha, Yogendra B; Ryu, Vitaly

    2014-10-01

    White adipose tissue (WAT) is innervated by the sympathetic nervous system (SNS) and its activation is necessary for lipolysis. WAT parasympathetic innervation is not supported. Fully-executed SNS-norepinephrine (NE)-mediated WAT lipolysis is dependent on β-adrenoceptor stimulation ultimately hinging on hormone sensitive lipase and perilipin A phosphorylation. WAT sympathetic drive is appropriately measured electrophysiologically and neurochemically (NE turnover) in non-human animals and this drive is fat pad-specific preventing generalizations among WAT depots and non-WAT organs. Leptin-triggered SNS-mediated lipolysis is weakly supported, whereas insulin or adenosine inhibition of SNS/NE-mediated lipolysis is strongly supported. In addition to lipolysis control, increases or decreases in WAT SNS drive/NE inhibit and stimulate white adipocyte proliferation, respectively. WAT sensory nerves are of spinal-origin and sensitive to local leptin and increases in sympathetic drive, the latter implicating lipolysis. Transsynaptic viral tract tracers revealed WAT central sympathetic and sensory circuits including SNS-sensory feedback loops that may control lipolysis. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Neural Innervation of White Adipose Tissue and the Control of Lipolysis

    PubMed Central

    Bartness, Timothy J.; Liu, Yang; Shrestha, Yogendra B.; Ryu, Vitaly

    2014-01-01

    White adipose tissue (WAT) is innervated by the sympathetic nervous system (SNS) and its activation is necessary for lipolysis. WAT parasympathetic innervation is not supported. Fully-executed SNS-norepinephrine (NE)-mediated WAT lipolysis is dependent on β-adrenoceptor stimulation ultimately hinging on hormone sensitive lipase and perilipin A phosphorylation. WAT sympathetic drive is appropriately measured by electrophysiological and neurochemical (NE turnover) in non-human animals and this drive is fat pad-specific preventing generalizations among WAT depots and non-WAT organs. Leptin-triggered SNS-mediated lipolysis is weakly supported, whereas insulin or adenosine inhibition of SNS/NE-mediated lipolysis is strongly supported. In addition to lipolysis control, increases or decreases in WAT SNS drive/NE inhibit and stimulate white adipocyte proliferation, respectively. WAT sensory nerves are of spinal-origin and sensitive to local leptin and increases in sympathetic drive, the latter implicating lipolysis. Transsynaptic viral tract tracer use revealed WAT central sympathetic and sensory circuits including SNS-sensory feedback loops that may control lipolysis. PMID:24736043

  11. Adipocyte Pseudohypoxia Suppresses Lipolysis and Facilitates Benign Adipose Tissue Expansion

    PubMed Central

    Morton, Nicholas M.; Moreno Navarrete, José Maria; West, Christopher C.; Stewart, Kenneth J.; Fernández-Real, José Manuel; Schofield, Christopher J.; Seckl, Jonathan R.; Ratcliffe, Peter J.

    2015-01-01

    Prolyl hydroxylase enzymes (PHDs) sense cellular oxygen upstream of hypoxia-inducible factor (HIF) signaling, leading to HIF degradation in normoxic conditions. In this study, we demonstrate that adipose PHD2 inhibition plays a key role in the suppression of adipocyte lipolysis. Adipose Phd2 gene ablation in mice enhanced adiposity, with a parallel increase in adipose vascularization associated with reduced circulating nonesterified fatty acid levels and normal glucose homeostasis. Phd2 gene–depleted adipocytes exhibited lower basal lipolysis in normoxia and reduced β-adrenergic–stimulated lipolysis in both normoxia and hypoxia. A selective PHD inhibitor suppressed lipolysis in murine and human adipocytes in vitro and in vivo in mice. PHD2 genetic ablation and pharmacological inhibition attenuated protein levels of the key lipolytic effectors hormone-sensitive lipase and adipose triglyceride lipase (ATGL), suggesting a link between adipocyte oxygen sensing and fatty acid release. PHD2 mRNA levels correlated positively with mRNA levels of AB-hydrolase domain containing-5, an activator of ATGL, and negatively with mRNA levels of lipid droplet proteins, perilipin, and TIP47 in human subcutaneous adipose tissue. Therapeutic pseudohypoxia caused by PHD2 inhibition in adipocytes blunts lipolysis and promotes benign adipose tissue expansion and may have therapeutic applications in obesity or lipodystrophy. PMID:25377876

  12. ADP-ribosylation factor 6 regulates endothelin-1-induced lipolysis in adipocytes.

    PubMed

    Davies, Jonathon C B; Bain, Stephen C; Kanamarlapudi, Venkateswarlu

    2014-08-15

    Endothelin-1 (ET-1) induces lipolysis in adipocytes, where ET-1 chronic exposure results in insulin resistance (IR) through suppression of glucose transporter (GLUT)4 translocation to the plasma membrane and consequently glucose uptake. ARF6 small GTPase, which plays a vital role in cell surface receptors trafficking, has previously been shown to regulate GLUT4 recycling and thereby insulin signalling. ARF6 also plays a role in ET-1 promoted endothelial cell migration. However, ARF6 involvement in ET-1-induced lipolysis in adipocytes is unknown. Therefore, we investigated the role of ARF6 in ET-1-induced lipolysis in 3T3-L1 adipocytes. This was achieved by studying the effect of inhibitors for the activation of ARF6 and other signalling proteins on ET-1 induced lipolysis and ARF6 activation in the adipocytes. Our results indicate that ET-1 induces, through endothelin type A receptor (ETAR), lipolysis, the ARF6 activation and extracellular-signal regulated kinase (ERK) phosphorylation in adipocytes, further ET-1 stimulated lipolysis is inhibited by the inhibitors of ARF6 activation, ERK phosphorylation and dynamin, which is essential for endocytosis. Our studies also revealed that ARF6 acts upstream of ERK in ET-1-indcued lipolysis. In summary, we determined that ET-1 activation of ETAR signalled through ARF6, which is crucial for lipolysis. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. The Lipid Droplet Protein Hypoxia-inducible Gene 2 Promotes Hepatic Triglyceride Deposition by Inhibiting Lipolysis*

    PubMed Central

    DiStefano, Marina T.; Danai, Laura V.; Roth Flach, Rachel J.; Chawla, Anil; Pedersen, David J.; Guilherme, Adilson; Czech, Michael P.

    2015-01-01

    The liver is a major site of glucose, fatty acid, and triglyceride (TG) synthesis and serves as a major regulator of whole body nutrient homeostasis. Chronic exposure of humans or rodents to high-calorie diets promotes non-alcoholic fatty liver disease, characterized by neutral lipid accumulation in lipid droplets (LD) of hepatocytes. Here we show that the LD protein hypoxia-inducible gene 2 (Hig2/Hilpda) functions to enhance lipid accumulation in hepatocytes by attenuating TG hydrolysis. Hig2 expression increased in livers of mice on a high-fat diet and during fasting, two states associated with enhanced hepatic TG content. Hig2 expressed in primary mouse hepatocytes localized to LDs and promoted LD TG deposition in the presence of oleate. Conversely, tamoxifen-inducible Hig2 deletion reduced both TG content and LD size in primary hepatocytes from mice harboring floxed alleles of Hig2 and a cre/ERT2 transgene controlled by the ubiquitin C promoter. Hepatic TG was also decreased by liver-specific deletion of Hig2 in mice with floxed Hig2 expressing cre controlled by the albumin promoter. Importantly, we demonstrate that Hig2-deficient hepatocytes exhibit increased TG lipolysis, TG turnover, and fatty acid oxidation as compared with controls. Interestingly, mice with liver-specific Hig2 deletion also display improved glucose tolerance. Taken together, these data indicate that Hig2 plays a major role in promoting lipid sequestration within LDs in mouse hepatocytes through a mechanism that impairs TG degradation. PMID:25922078

  14. The Lipid Droplet Protein Hypoxia-inducible Gene 2 Promotes Hepatic Triglyceride Deposition by Inhibiting Lipolysis.

    PubMed

    DiStefano, Marina T; Danai, Laura V; Roth Flach, Rachel J; Chawla, Anil; Pedersen, David J; Guilherme, Adilson; Czech, Michael P

    2015-06-12

    The liver is a major site of glucose, fatty acid, and triglyceride (TG) synthesis and serves as a major regulator of whole body nutrient homeostasis. Chronic exposure of humans or rodents to high-calorie diets promotes non-alcoholic fatty liver disease, characterized by neutral lipid accumulation in lipid droplets (LD) of hepatocytes. Here we show that the LD protein hypoxia-inducible gene 2 (Hig2/Hilpda) functions to enhance lipid accumulation in hepatocytes by attenuating TG hydrolysis. Hig2 expression increased in livers of mice on a high-fat diet and during fasting, two states associated with enhanced hepatic TG content. Hig2 expressed in primary mouse hepatocytes localized to LDs and promoted LD TG deposition in the presence of oleate. Conversely, tamoxifen-inducible Hig2 deletion reduced both TG content and LD size in primary hepatocytes from mice harboring floxed alleles of Hig2 and a cre/ERT2 transgene controlled by the ubiquitin C promoter. Hepatic TG was also decreased by liver-specific deletion of Hig2 in mice with floxed Hig2 expressing cre controlled by the albumin promoter. Importantly, we demonstrate that Hig2-deficient hepatocytes exhibit increased TG lipolysis, TG turnover, and fatty acid oxidation as compared with controls. Interestingly, mice with liver-specific Hig2 deletion also display improved glucose tolerance. Taken together, these data indicate that Hig2 plays a major role in promoting lipid sequestration within LDs in mouse hepatocytes through a mechanism that impairs TG degradation.

  15. Interaction of the Clostridium difficile Binary Toxin CDT and Its Host Cell Receptor, Lipolysis-stimulated Lipoprotein Receptor (LSR)*

    PubMed Central

    Hemmasi, Sarah; Czulkies, Bernd A.; Schorch, Björn; Veit, Antonia; Aktories, Klaus; Papatheodorou, Panagiotis

    2015-01-01

    CDT (Clostridium difficile transferase) is a binary, actin ADP-ribosylating toxin frequently associated with hypervirulent strains of the human enteric pathogen C. difficile, the most serious cause of antibiotic-associated diarrhea and pseudomembranous colitis. CDT leads to the collapse of the actin cytoskeleton and, eventually, to cell death. Low doses of CDT result in the formation of microtubule-based protrusions on the cell surface that increase the adherence and colonization of C. difficile. The lipolysis-stimulated lipoprotein receptor (LSR) is the host cell receptor for CDT, and our aim was to gain a deeper insight into the interplay between both proteins. We show that CDT interacts with the extracellular, Ig-like domain of LSR with an affinity in the nanomolar range. We identified LSR splice variants in the colon carcinoma cell line HCT116 and disrupted the LSR gene in these cells by applying the CRISPR-Cas9 technology. LSR truncations ectopically expressed in LSR knock-out cells indicated that intracellular parts of LSR are not essential for plasma membrane targeting of the receptor and cellular uptake of CDT. By generating a series of N- and C-terminal truncations of the binding component of CDT (CDTb), we found that amino acids 757–866 of CDTb are sufficient for binding to LSR. With a transposon-based, random mutagenesis approach, we identified potential LSR-interacting epitopes in CDTb. This study increases our understanding about the interaction between CDT and its receptor LSR, which is key to the development of anti-toxin strategies for preventing cell entry of the toxin. PMID:25882847

  16. Differentiation of human adipocytes at physiological oxygen levels results in increased adiponectin secretion and isoproterenol-stimulated lipolysis.

    PubMed

    Famulla, Susanne; Schlich, Raphaela; Sell, Henrike; Eckel, Jürgen

    2012-07-01

    Adipose tissue (AT) hypoxia occurs in obese humans and mice. Acute hypoxia in adipocytes causes dysregulation of adipokine secretion with an increase in inflammatory factors and diminished adiponectin release. O2 levels in humans range between 3 and 11% revealing that conventional in vitro culturing at ambient air and acute hypoxia treatment (1% O2) are performed under non-physiological conditions. In this study, we mimicked physiological conditions by differentiating human primary adipocytes under 10% or 5% O2 in comparison to 21% O2. Induction of differentiation markers was comparable between all three conditions. Adipokine release by adipocytes differentiated at lower oxygen levels was altered, with a marked upregulation of adiponectin, IL-6 and DPP4 secretion, and reduced leptin levels compared with adipocytes differentiated at 21% O2. Isoproterenol-induced lipolysis was significantly elevated in adipocytes differentiated at 10% and 5% compared with 21% O2. This effect was accompanied by increased protein expression of β-1 and -2 adrenergic receptor, HSL and perilipin. Conditioned medium (CM) of adipocytes differentiated at the three different conditions was generated for stimulation of human skeletal muscle cells (SkMC) or smooth muscle cells (SMC). CM-induced insulin resistance in SkMC was comparable for the different CMs. However, the SMC proliferative effect of CM from adipocytes differentiated at 10% O2 was significantly reduced compared with 21% O2. This study demonstrates that oxygen levels during adipogenesis are important factors altering adipocyte functionality such as adipokine release, in particular adiponectin secretion, as well as the hormone-induced lipolytic pathway.

  17. Differentiation of human adipocytes at physiological oxygen levels results in increased adiponectin secretion and isoproterenol-stimulated lipolysis

    PubMed Central

    Famulla, Susanne; Schlich, Raphaela; Sell, Henrike; Eckel, Jürgen

    2012-01-01

    Adipose tissue (AT) hypoxia occurs in obese humans and mice. Acute hypoxia in adipocytes causes dysregulation of adipokine secretion with an increase in inflammatory factors and diminished adiponectin release. O2 levels in humans range between 3 and 11% revealing that conventional in vitro culturing at ambient air and acute hypoxia treatment (1% O2) are performed under non-physiological conditions. In this study, we mimicked physiological conditions by differentiating human primary adipocytes under 10% or 5% O2 in comparison to 21% O2. Induction of differentiation markers was comparable between all three conditions. Adipokine release by adipocytes differentiated at lower oxygen levels was altered, with a marked upregulation of adiponectin, IL-6 and DPP4 secretion, and reduced leptin levels compared with adipocytes differentiated at 21% O2. Isoproterenol-induced lipolysis was significantly elevated in adipocytes differentiated at 10% and 5% compared with 21% O2. This effect was accompanied by increased protein expression of β-1 and -2 adrenergic receptor, HSL and perilipin. Conditioned medium (CM) of adipocytes differentiated at the three different conditions was generated for stimulation of human skeletal muscle cells (SkMC) or smooth muscle cells (SMC). CM-induced insulin resistance in SkMC was comparable for the different CMs. However, the SMC proliferative effect of CM from adipocytes differentiated at 10% O2 was significantly reduced compared with 21% O2. This study demonstrates that oxygen levels during adipogenesis are important factors altering adipocyte functionality such as adipokine release, in particular adiponectin secretion, as well as the hormone-induced lipolytic pathway. PMID:23700522

  18. The roles of tricellular tight junction protein lipolysis-stimulated lipoprotein receptor in malignancy of human endometrial cancer cells

    PubMed Central

    Shimada, Hiroshi; Satohisa, Seiro; Kohno, Takayuki; Takahashi, Syunta; Hatakeyama, Tsubasa; Konno, Takumi; Tsujiwaki, Mitsuhiro; Saito, Tsuyoshi; Kojima, Takashi

    2016-01-01

    Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a novel molecular constituent of tricellular contacts that have a barrier function for the cellular sheet. LSR recruits tricellulin (TRIC), which is the first molecular component of tricellular tight junctions. Knockdown of LSR increases cell motility and invasion of certain cancer cells. However, the behavior and the roles of LSR in endometrial cancer remain unknown. In the present study, we investigated the behavior and roles of LSR in normal and endometrial cancer cells in vivo and in vitro. In endometriosis and endometrial cancer, LSR was observed not only in the subapical region but also throughout the lateral region as well as in normal endometrial epithelial cells in the secretory phase, and LSR in the cancer was reduced in correlation with the malignancy. Knockdown of LSR by the siRNA in cells of the endometrial cancer cell line Sawano, induced cell migration, invasion and proliferation, while TRIC relocalized from the tricellular region to the bicellular region at the membrane. In Sawano cells and normal HEEs, a decrease of LSR induced by leptin and an increase of LSR induced by adiponectin and the drugs for type 2 diabetes metformin and berberine were observed via distinct signaling pathways including JAK2/STAT. In Sawano cells, metformin and berberine prevented cell migration and invasion induced by downregulation of LSR by the siRNA and leptin treatment. The dissection of the mechanism in the downregulation of endometrial LSR during obesity is important in developing new diagnostic and therapy for endometrial cancer. PMID:27036040

  19. Interaction of the Clostridium difficile Binary Toxin CDT and Its Host Cell Receptor, Lipolysis-stimulated Lipoprotein Receptor (LSR).

    PubMed

    Hemmasi, Sarah; Czulkies, Bernd A; Schorch, Björn; Veit, Antonia; Aktories, Klaus; Papatheodorou, Panagiotis

    2015-05-29

    CDT (Clostridium difficile transferase) is a binary, actin ADP-ribosylating toxin frequently associated with hypervirulent strains of the human enteric pathogen C. difficile, the most serious cause of antibiotic-associated diarrhea and pseudomembranous colitis. CDT leads to the collapse of the actin cytoskeleton and, eventually, to cell death. Low doses of CDT result in the formation of microtubule-based protrusions on the cell surface that increase the adherence and colonization of C. difficile. The lipolysis-stimulated lipoprotein receptor (LSR) is the host cell receptor for CDT, and our aim was to gain a deeper insight into the interplay between both proteins. We show that CDT interacts with the extracellular, Ig-like domain of LSR with an affinity in the nanomolar range. We identified LSR splice variants in the colon carcinoma cell line HCT116 and disrupted the LSR gene in these cells by applying the CRISPR-Cas9 technology. LSR truncations ectopically expressed in LSR knock-out cells indicated that intracellular parts of LSR are not essential for plasma membrane targeting of the receptor and cellular uptake of CDT. By generating a series of N- and C-terminal truncations of the binding component of CDT (CDTb), we found that amino acids 757-866 of CDTb are sufficient for binding to LSR. With a transposon-based, random mutagenesis approach, we identified potential LSR-interacting epitopes in CDTb. This study increases our understanding about the interaction between CDT and its receptor LSR, which is key to the development of anti-toxin strategies for preventing cell entry of the toxin. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. The roles of tricellular tight junction protein lipolysis-stimulated lipoprotein receptor in malignancy of human endometrial cancer cells.

    PubMed

    Shimada, Hiroshi; Satohisa, Seiro; Kohno, Takayuki; Takahashi, Syunta; Hatakeyama, Tsubasa; Konno, Takumi; Tsujiwaki, Mitsuhiro; Saito, Tsuyoshi; Kojima, Takashi

    2016-05-10

    Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a novel molecular constituent of tricellular contacts that have a barrier function for the cellular sheet. LSR recruits tricellulin (TRIC), which is the first molecular component of tricellular tight junctions. Knockdown of LSR increases cell motility and invasion of certain cancer cells. However, the behavior and the roles of LSR in endometrial cancer remain unknown. In the present study, we investigated the behavior and roles of LSR in normal and endometrial cancer cells in vivo and in vitro. In endometriosis and endometrial cancer, LSR was observed not only in the subapical region but also throughout the lateral region as well as in normal endometrial epithelial cells in the secretory phase, and LSR in the cancer was reduced in correlation with the malignancy. Knockdown of LSR by the siRNA in cells of the endometrial cancer cell line Sawano, induced cell migration, invasion and proliferation, while TRIC relocalized from the tricellular region to the bicellular region at the membrane. In Sawano cells and normal HEEs, a decrease of LSR induced by leptin and an increase of LSR induced by adiponectin and the drugs for type 2 diabetes metformin and berberine were observed via distinct signaling pathways including JAK2/STAT. In Sawano cells, metformin and berberine prevented cell migration and invasion induced by downregulation of LSR by the siRNA and leptin treatment. The dissection of the mechanism in the downregulation of endometrial LSR during obesity is important in developing new diagnostic and therapy for endometrial cancer.

  1. Overexpression of G0/G1 Switch Gene 2 in Adipose Tissue of Transgenic Quail Inhibits Lipolysis Associated with Egg Laying

    PubMed Central

    Chen, Paula Renee; Shin, Sangsu; Choi, Young Min; Kim, Elizabeth; Han, Jae Yong; Lee, Kichoon

    2016-01-01

    In avians, yolk synthesis is regulated by incorporation of portomicrons from the diet, transport of lipoproteins from the liver, and release of lipids from adipose tissue; however, the extent to which lipolysis in adipose tissue contributes to yolk synthesis and egg production has yet to be elucidated. G0/G1 switch gene 2 (G0S2) is known to bind and inhibit adipose triglyceride lipase (ATGL), the rate-limiting enzyme in lipolysis. The objective of this study was to determine whether overexpression of the G0S2 gene in adipose tissue could successfully inhibit endogenous ATGL activity associated with egg laying. Two independent lines of transgenic quail overexpressing G0S2 had delayed onset of egg production and reduced number of eggs over a six-week period compared to non-transgenic quail. Although no differences in measured parameters were observed at the pre-laying stage (5 weeks of age), G0S2 transgenic quail had significantly larger interclavicular fat pad weights and adipocyte sizes and lower NEFA concentrations in the serum at early (1 week after laying first egg) and active laying (5 weeks after laying first egg) stages. Overexpression of G0S2 inhibited lipolysis during early and active laying, which drastically shifted the balance towards a net accumulation of triacylglycerols and increased adipose tissue mass. Thereby, egg production was negatively affected as less triacylglycerols were catabolized to produce lipids for the yolk. PMID:26999108

  2. Overexpression of G0/G1 Switch Gene 2 in Adipose Tissue of Transgenic Quail Inhibits Lipolysis Associated with Egg Laying.

    PubMed

    Chen, Paula Renee; Shin, Sangsu; Choi, Young Min; Kim, Elizabeth; Han, Jae Yong; Lee, Kichoon

    2016-03-15

    In avians, yolk synthesis is regulated by incorporation of portomicrons from the diet, transport of lipoproteins from the liver, and release of lipids from adipose tissue; however, the extent to which lipolysis in adipose tissue contributes to yolk synthesis and egg production has yet to be elucidated. G0/G1 switch gene 2 (G0S2) is known to bind and inhibit adipose triglyceride lipase (ATGL), the rate-limiting enzyme in lipolysis. The objective of this study was to determine whether overexpression of the G0S2 gene in adipose tissue could successfully inhibit endogenous ATGL activity associated with egg laying. Two independent lines of transgenic quail overexpressing G0S2 had delayed onset of egg production and reduced number of eggs over a six-week period compared to non-transgenic quail. Although no differences in measured parameters were observed at the pre-laying stage (5 weeks of age), G0S2 transgenic quail had significantly larger interclavicular fat pad weights and adipocyte sizes and lower NEFA concentrations in the serum at early (1 week after laying first egg) and active laying (5 weeks after laying first egg) stages. Overexpression of G0S2 inhibited lipolysis during early and active laying, which drastically shifted the balance towards a net accumulation of triacylglycerols and increased adipose tissue mass. Thereby, egg production was negatively affected as less triacylglycerols were catabolized to produce lipids for the yolk.

  3. Immunogenic inhibition of prominent ruminal bacteria as a means to reduce lipolysis and biohydrogenation activity in vitro

    USDA-ARS?s Scientific Manuscript database

    Through the microbial processes of lipolysis and biohydrogenation, ruminal animals promote the accumulation of saturated fatty acids in their meat and milk. Anaerovibrio lipolyticus, Butyrivibrio fibrisolvens, and Propionibacterium avidum and acnes have been identified as contributors to ruminal li...

  4. Fat-reducing effects of dehydroepiandrosterone involve upregulation of ATGL and HSL expression, and stimulation of lipolysis in adipose tissue.

    PubMed

    Karbowska, Joanna; Kochan, Zdzislaw

    2012-11-01

    Dehydroepiandrosterone (DHEA) reduces body fat in rodents and humans, and increases glycerol release from isolated rat epididymal adipocytes and human visceral adipose tissue explants. It suggests that DHEA stimulates triglyceride hydrolysis in adipose tissue; however, the mechanisms underlying this action are still unclear. We examined the effects of DHEA on the expression of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), the key enzymes of lipolysis, in rat epididymal white adipose tissue (eWAT). Male Wistar rats were fed a diet containing 0.6% DHEA for 2 weeks and eWAT was analyzed for mRNA and protein expression of ATGL and HSL, as well as mRNA expression of peroxisome proliferator-activated receptor γ 2 (PPARγ2) and its downstream target fatty acid translocase (FAT). Glycerol release from eWAT explants and serum free fatty acids (FFA) were also measured. Rats that received DHEA gained less weight, had 23% lower eWAT mass and 31% higher serum FFA levels than controls. Cultured explants of eWAT from DHEA-treated rats released 81% more glycerol than those from control rats. DHEA administration upregulated ATGL mRNA (1.62-fold, P<0.05) and protein (1.78-fold, P<0.05) expression as well as augmented HSL mRNA levels (1.36-fold, P<0.05) and Ser660 phosphorylation of HSL (2.49-fold, P<0.05). PPARγ2 and FAT mRNA levels were also increased in DHEA-treated rats (1.61-fold, P<0.05 and 2.16-fold, P<0.05; respectively). Moreover, ATGL, HSL, and FAT mRNA levels were positively correlated with PPARγ2 expression. This study demonstrates that DHEA promotes lipid mobilization in adipose tissue by increasing the expression and activity of ATGL and HSL. The effects of DHEA appear to be mediated, at least in part, via PPARγ2 activation, which in turn upregulates ATGL and HSL gene expression. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Motor cortex inhibition induced by acoustic stimulation.

    PubMed

    Kühn, Andrea A; Sharott, Andrew; Trottenberg, Thomas; Kupsch, Andreas; Brown, Peter

    2004-09-01

    The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following acoustic stimulation occurs at the level of the motor cortex through reticulo-cortical projections or subcortically, perhaps through reticulo-spinal projections. We compared the influence of acoustic stimulation on motor effects elicited by TMS over motor cortical areas to those evoked with subcortical electrical stimulation (SES) through depth electrodes in five patients treated with deep brain stimulation for Parkinson's disease. SES bypasses the motor cortex, demonstrating any interaction with acoustic stimuli at the subcortical level. EMG was recorded from the contralateral biceps brachii muscle. Acoustic stimulation was delivered binaurally through headphones and used as a conditioning stimulus at an interstimulus interval of 50 ms. When TMS was used as the test stimulus, the area and amplitude of the conditioned motor response was significantly inhibited (area: 57.5+/-12.9%, amplitude: 47.9+/-7.4%, as percentage of unconditioned response) whereas facilitation occurred with SES (area: 110.1+/-4.3%, amplitude: 116.9+/-6.9%). We conclude that a startle-evoked activation of reticulo-cortical projections transiently inhibits the motor cortex.

  6. Amino acid-sensing mTOR signaling is involved in modulation of lipolysis by chronic insulin treatment in adipocytes.

    PubMed

    Zhang, Chongben; Yoon, Mee-Sup; Chen, Jie

    2009-04-01

    Chronically high insulin levels and increased circulating free fatty acids released from adipose tissue through lipolysis are two features associated with insulin resistance. The relationship between chronic insulin exposure and adipocyte lipolysis has been unclear. In the present study we found that chronic insulin exposure in 3T3-L1 adipocytes, as well as in mouse primary adipocytes, increased basal lipolysis rates. This effect of insulin on lipolysis was only observed when the mammalian target of rapamycin (mTOR) pathway was inhibited by rapamycin in the adipocytes. In addition, amino acid deprivation in adipocytes phenocopied the effect of rapamycin in permitting the stimulation of lipolysis by chronic insulin exposure. The phosphatidylinositol 3-kinase-Akt pathway does not appear to be involved in this insulin effect. Furthermore, we found that triacylglycerol hydrolase (TGH) activity was required for the stimulation of lipolysis by combined exposure to insulin and rapamycin. Therefore, we propose that nutrient sufficiency, mediated by an mTOR pathway, suppresses TGH-dependent lipolysis stimulated by chronic insulin exposure in adipocytes.

  7. Characterization of Eicosanoids Produced by Adipocyte Lipolysis: IMPLICATION OF CYCLOOXYGENASE-2 IN ADIPOSE INFLAMMATION.

    PubMed

    Gartung, Allison; Zhao, Jiawei; Chen, Simon; Mottillo, Emilio; VanHecke, Garrett C; Ahn, Young-Hoon; Maddipati, Krishna Rao; Sorokin, Andrey; Granneman, James; Lee, Menq-Jer

    2016-07-29

    Excessive adipocyte lipolysis generates lipid mediators and triggers inflammation in adipose tissue. However, the specific roles of lipolysis-generated mediators in adipose inflammation remain to be elucidated. In the present study, cultured 3T3-L1 adipocytes were treated with isoproterenol to activate lipolysis and the fatty acyl lipidome of released lipids was determined by using LC-MS/MS. We observed that β-adrenergic activation elevated levels of approximately fifty lipid species, including metabolites of cyclooxygenases, lipoxygenases, epoxygenases, and other sources. Moreover, we found that β-adrenergic activation induced cyclooxygenase 2 (COX-2), not COX-1, expression in a manner that depended on activation of hormone-sensitive lipase (HSL) in cultured adipocytes and in the epididymal white adipose tissue (EWAT) of C57BL/6 mice. We found that lipolysis activates the JNK/NFκB signaling pathway and inhibition of the JNK/NFκB axis abrogated the lipolysis-stimulated COX-2 expression. In addition, pharmacological inhibition of COX-2 activity diminished levels of COX-2 metabolites during lipolytic activation. Inhibition of COX-2 abrogated the induction of CCL2/MCP-1 expression by β-adrenergic activation and prevented recruitment of macrophage/monocyte to adipose tissue. Collectively, our data indicate that excessive adipocyte lipolysis activates the JNK/NFκB pathway leading to the up-regulation of COX-2 expression and recruitment of inflammatory macrophages. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. Kisspeptin-10 inhibits proliferation and regulates lipolysis and lipogenesis processes in 3T3-L1 cells and isolated rat adipocytes.

    PubMed

    Pruszyńska-Oszmałek, Ewa; Kołodziejski, Paweł A; Sassek, Maciej; Sliwowska, Joanna H

    2017-04-01

    Kisspeptin, which is encoded by the KISS1 gene and acts via GPR54, plays a role in the regulation of reproductive functions. Expression of KISS1 and GRPR54 has been found in peripheral tissues, including adipose tissue, and was shown to be influenced by metabolic status. We hypothesized that kisspeptin could be involved in regulation of lipid metabolism in the mouse 3T3-L1 cell line and in isolated rat adipocytes. First, we characterized expression profiles of KISS1 and GPR54 mRNA and proteins in adipose cells isolated from male rats. Secondly, we studied the effects of kisspeptin-10 on cell proliferation and survival in 3T3-L1 cells. Thirdly, we assessed the rapid action of kisspeptin-10 on lipid metabolism and glucose uptake using 3T3-L1 cells and rat primary adipocytes. Finally, we examined the effects of kisspeptin-10 on the secretion of leptin and adiponectin in rat adipocytes. We have found that: (1) KISS1 and GPR54 were expressed in mouse 3T3-L1 cells and isolated rat adipocytes; (2) kisspeptin-10: (i) inhibited cell proliferation, viability and adipogenesis in 3T3-L1 and decreased expression of PPAR-γ and CEBPβ-genes, which are involved in the differentiation processes and adipogenesis; (ii) increased lipolysis in 3T3-L1 cells and rat adipocytes by enhancing expression of periliphin and hormone-sensitive lipase; (iii) modulated glucose uptake and lipogenesis; (iv) stimulated leptin and decreased adiponectin secretion from rat adipocytes. Kisspeptin-10 could play a role in the regulation of lipid metabolism in mouse 3T3-L1 cells and rat adipocytes.

  9. Jueming prescription and its ingredients, semen cassiae and Rhizoma Curcumae Longae, stimulate lipolysis and enhance the phosphorylation of hormone‑sensitive lipase in cultured rat white adipose tissue.

    PubMed

    Zhang, Yue; Li, Jiaojiao; Wen, Xiuying

    2017-08-22

    The present study aimed to investigate the effect of jueming prescription (JMP) and its ingredients, semen cassiae (SC) and Rhizoma Curcumae Longae (RCL), on lipolysis, and to examine their effect on the phosphorylation of hormone‑sensitive lipase (HSL) in cultured rat white adipose tissue (WAT). Retroperitoneal WAT was aseptically excised from adult male Sprague‑Dawley rats, minced into uniform sections and subjected to ex vivo culture for 24 h. The tissue sections were then distributed into a 24‑well culture plate and treated with normal saline (vehicle), isoproterenol (ISO), JMP, SC and RCL. Non‑esterified fatty acid (NEFA) and glycerol release from the intact WAT explants were determined as a measurement of lipolysis, which were measured using NEFA and glycerol assay kits. The phosphorylation of HSL at Ser563 (P‑HSL S563) and 660 residues (P‑HSL S660) were determined using western blot analysis. The size of the adipocytes was visualized using hematoxylin and eosin (H&E) staining. It was found that JMP‑, SC‑ and RCL‑stimulated lipolysis was responsible for increasing the release of NEFAs and glycerol from the intact WAT in vitro. In addition, JMP, SC and RCL increased the levels of P‑HSL Ser563: JMP water (JW) extract, 3.52‑fold; JMP ethanol (JE) extract, 3.38‑fold; SC water (SW) extract, 4.60‑fold; SC ethanol (SE) extract, 4.20‑fold; RCL water (RW) extract, 6.98‑fold; RCL ethanol (RE) extract, 6.60‑fold. JMP, SC and RCL also increased the levels of P‑HSL Ser660: JW extract, 3.16‑fold; JE extract, 2.92‑fold; SW extract, 4.57‑fold; SE extract, 4.13‑fold; RW extract, 5.41‑fold; RE 4.96‑fold) in the WAT. The RW extract had the most marked effect. The HE staining revealed that JMP, SC and RCL reduced the size of adipocytes in the WAT. In conclusion, JMP and its ingredients, SC and RC, stimulated lipolysis and reduced the size of adipocytes, possibly via the phosphorylation of HSL in cultured rat WAT.

  10. Thiazolidinediones attenuate lipolysis and ameliorate dexamethasone-induced insulin resistance.

    PubMed

    He, Jinhan; Xu, Chong; Kuang, Jiangying; Liu, Qinhui; Jiang, Hongfeng; Mo, Li; Geng, Bin; Xu, Guoheng

    2015-07-01

    Elevated levels of circulating free fatty acids induce insulin resistance and often occur in obese and diabetic conditions. One pharmacological basis for the antidiabetic effects of thiazolidinediones (TZDs) is that TZDs reduce levels of circulating FFAs by accelerating their uptake and reesterification from plasma into adipocytes. Here, we investigated whether TZDs affect adipose lipolysis, a process controlling triglyceride hydrolysis and FFA efflux to the bloodstream. The effects of TZDs on lipolysis were investigated in primary rat adipocytes in vitro and in rats in vivo. In rat primary adipocytes, the TZDs pioglitazone, rosiglitazone and troglitazone inhibited the lipolytic reaction dose- and time-dependently and in a post-receptor pathway by decreasing cAMP level and total lipase activity. TZDs increased the phosphorylation of Akt/protein kinase B, an action required for activating cyclic-nucleotide phosphodiesterase 3B, a major enzyme responsible for cAMP hydrolysis in adipocytes. Furthermore, rosiglitazone inhibited the lipolytic action in dexamethasone-stimulated adipocytes, thereby preventing the increased level of circulating FFAs, and ameliorated insulin resistance in vivo in dexamethasone-treated rats. TZDs may attenuate lipolysis and FFA efflux by activating Akt signaling to decrease cAMP level and hence reduce lipase activity in adipocytes. Inhibiting lipolysis and FFA efflux with TZDs could be a pharmacological basis by which TZDs antagonize diabetes, particularly in patients with hypercortisolemia or glucocorticoid challenge. Copyright © 2015. Published by Elsevier Inc.

  11. Increase or decrease hydrogen sulfide exert opposite lipolysis, but reduce global insulin resistance in high fatty diet induced obese mice.

    PubMed

    Geng, Bin; Cai, Bo; Liao, Feng; Zheng, Yang; Zeng, Qiang; Fan, Xiaofang; Gong, Yongsheng; Yang, Jichun; Cui, Qing Hua; Tang, Chaoshu; Xu, Guo Heng

    2013-01-01

    Adipose tissue expressed endogenous cystathionine gamma lyase (CSE)/hydrogen sulfide (H2S) system. H2S precursor inhibited catecholamine stimulated lipolysis. Thus, we hypothesized that CSE/H2S system regulates lipolysis which contributed to the pathogenesis of insulin resistance. We treated rat adipocyte with DL-propargylglycine (PAG, a CSE inhibitor), L-cysteine (an H2S precursor) plus pyridoxial phosphate (co-enzyme) or the H2S chronic release donor GYY4137, then the glycerol level was assayed for assessing the lipolysis. Then, the effects of PAG and GYY4137 on insulin resistance in high fatty diet (HFD) induced obese mice were investigated. Here, we found that PAG time-dependently increased basal or isoproterenol stimulated lipolysis. However, L-cysteine plus pyridoxial phosphate or GYY4137 significantly reduced it. PAG increased phosphorylated protein kinase A substrate, perilipin 1 and hormone sensitive lipase, but L-cysteine and GYY4137 decreased the parameters. In HFD induced obese mice, PAG increased adipose basal lipolysis, thus blunted fat mass increase, resulting in lowering insulin resistance evidenced by reduction of fasting glucose, insulin level, HOMA index, oral glucose tolerance test (OGTT) curve area and elevating the insulin tolerance test (ITT) response. GYY4137 inhibited lipolysis in vivo without increasing fat mass, but also ameliorated the insulin resistance in HFD mice. These results implicated that inhibition endogenous CSE/H2S system in adipocytes increased lipolysis by a protein kinase A-perilipin/hormone-sensitive lipase pathway, thus blunted fat mass increase and reduced insulin resistance in obese mice; giving H2S donor decreased lipolysis, also reduced insulin resistance induced by HFD. Our data showed that increase or decrease H2S induced opposite lipolysis, but had the same effect on insulin resistance. The paradoxical regulation may be resulted from different action of H2S on metabolic and endocrine function in adipocyte.

  12. Increase or Decrease Hydrogen Sulfide Exert Opposite Lipolysis, but Reduce Global Insulin Resistance in High Fatty Diet Induced Obese Mice

    PubMed Central

    Geng, Bin; Cai, Bo; Liao, Feng; Zheng, Yang; Zeng, Qiang; Fan, Xiaofang; Gong, Yongsheng; Yang, Jichun; Cui, Qing hua; Tang, Chaoshu; Xu, Guo heng

    2013-01-01

    Objective Adipose tissue expressed endogenous cystathionine gamma lyase (CSE)/hydrogen sulfide (H2S) system. H2S precursor inhibited catecholamine stimulated lipolysis. Thus, we hypothesized that CSE/H2S system regulates lipolysis which contributed to the pathogenesis of insulin resistance. Methods We treated rat adipocyte with DL-propargylglycine (PAG, a CSE inhibitor), L-cysteine (an H2S precursor) plus pyridoxial phosphate (co-enzyme) or the H2S chronic release donor GYY4137, then the glycerol level was assayed for assessing the lipolysis. Then, the effects of PAG and GYY4137 on insulin resistance in high fatty diet (HFD) induced obese mice were investigated. Results Here, we found that PAG time-dependently increased basal or isoproterenol stimulated lipolysis. However, L-cysteine plus pyridoxial phosphate or GYY4137 significantly reduced it. PAG increased phosphorylated protein kinase A substrate, perilipin 1 and hormone sensitive lipase, but L-cysteine and GYY4137 decreased the parameters. In HFD induced obese mice, PAG increased adipose basal lipolysis, thus blunted fat mass increase, resulting in lowering insulin resistance evidenced by reduction of fasting glucose, insulin level, HOMA index, oral glucose tolerance test (OGTT) curve area and elevating the insulin tolerance test (ITT) response. GYY4137 inhibited lipolysis in vivo without increasing fat mass, but also ameliorated the insulin resistance in HFD mice. Conclusion These results implicated that inhibition endogenous CSE/H2S system in adipocytes increased lipolysis by a protein kinase A-perilipin/hormone-sensitive lipase pathway, thus blunted fat mass increase and reduced insulin resistance in obese mice; giving H2S donor decreased lipolysis, also reduced insulin resistance induced by HFD. Our data showed that increase or decrease H2S induced opposite lipolysis, but had the same effect on insulin resistance. The paradoxical regulation may be resulted from different action of H2S on metabolic and

  13. Vagus nerve stimulation inhibits cortical spreading depression.

    PubMed

    Chen, Shih-Pin; Ay, Ilknur; de Morais, Andreia Lopes; Qin, Tao; Zheng, Yi; Sadeghian, Homa; Oka, Fumiaki; Simon, Bruce; Eikermann-Haerter, Katharina; Ayata, Cenk

    2016-04-01

    Vagus nerve stimulation has recently been reported to improve symptoms of migraine. Cortical spreading depression is the electrophysiological event underlying migraine aura and is a trigger for headache. We tested whether vagus nerve stimulation inhibits cortical spreading depression to explain its antimigraine effect. Unilateral vagus nerve stimulation was delivered either noninvasively through the skin or directly by electrodes placed around the nerve. Systemic physiology was monitored throughout the study. Both noninvasive transcutaneous and invasive direct vagus nerve stimulations significantly suppressed spreading depression susceptibility in the occipital cortex in rats. The electrical stimulation threshold to evoke a spreading depression was elevated by more than 2-fold, the frequency of spreading depressions during continuous topical 1 M KCl was reduced by ∼40%, and propagation speed of spreading depression was reduced by ∼15%. This effect developed within 30 minutes after vagus nerve stimulation and persisted for more than 3 hours. Noninvasive transcutaneous vagus nerve stimulation was as efficacious as direct invasive vagus nerve stimulation, and the efficacy did not differ between the ipsilateral and contralateral hemispheres. Our findings provide a potential mechanism by which vagus nerve stimulation may be efficacious in migraine and suggest that susceptibility to spreading depression is a suitable platform to optimize its efficacy.

  14. Calciotropic hormones and lipolysis of human adipose tissue: role of extracellular calcium as conditioning but not regulating factor.

    PubMed

    Ziegler, R; Jobst, W; Minne, H; Faulhaber, J D

    1980-01-01

    The influences of different calcium concentrations (0, 0.924 and 2.772 mMol/l) on lipolysis of in vitro incubated human adipose tissue slices or adipocytes were studied under the conditions of stimulation with isoproterenol and parathyroid hormone preparations or inhibition by insulin. Extractive bovine PTH (as well as synthetic PTH 1--34) stimulated glycerol release in a biphasic pattern similarly to isoproterenol; PTH was about half as potent as isoproterenol. The optimal conditions for lipolysis were observed using a calcium concentration of 0.924 mMol/l, whereas lipolysis was distinctly impaired at concentrations of 0 or 2.772 mMol/l; this was true for basal as well as isoproterenol- and PTH stimulated lipolysis or the inhibitory effect of insulin. In contrast to partially purified extractive calcitonin, pure synthetic calcitonin did not inhibit lipolysis. Isoproterenol- and PTH-administrations led to cAMP accumulation in the adipose tissue, this process was also diminished at the non-optimal calcium concentrations. The results suggest a conditioning, but not a regulating significance of extracellular calcium for lipolysis, whereas the importance of the lipolytic potency of PTH remains to be elucidated.

  15. Adipose tissue lipolysis as a metabolic pathway to define pharmacological strategies against obesity and the metabolic syndrome.

    PubMed

    Langin, Dominique

    2006-06-01

    Adipose tissue lipolysis is the catabolic process leading to the breakdown of triglycerides stored in fat cells and release of fatty acids and glycerol. Recent work has revealed that lipolysis is not a simple metabolic pathway stimulated by catecholamines and inhibited by insulin. There have been new discoveries on the endocrine and paracrine regulation of lipolysis and on the molecular mechanisms of triglyceride hydrolysis. Catecholamines modulate lipolysis through lipolytic beta-adrenoceptor and antilipolytic alpha2-adrenoceptor. Recent studies have allowed a better understanding of the relative contribution of the two types of receptors and provided evidence for the in vivo involvement of alpha2-adrenoceptors in the physiological control of subcutaneous adipose tissue lipolysis. A puzzling observation is the characterization of a residual catecholamine-induced lipolysis in mice deficient in beta-adrenoceptors. A novel lipolytic system has been characterized in human fat cells. Natriuretic peptides stimulate lipolysis through a cGMP-dependent pathway. There are other lipolytic pathways active in human fat cells which importance is not fully understood. Forty years after the description of the antilipolytic effect of nicotinic acid, the receptors have been identified. Adrenomedullin which is produced by adipocytes exert an antilipolytic effect through an indirect mechanism involving nitric oxide. The molecular details of the lipolytic reaction are not fully understood. The role of the lipases has been re-evaluated with the cloning of adipose triglyceride lipase. Hormone-sensitive lipase appears as the major lipase for catecholamine and natriuretic peptide-stimulated lipolysis whereas adipose triglyceride lipase mediates the hydrolysis of triglycerides during basal lipolysis. Translocation of hormone-sensitive lipase bound to the adipocyte lipid binding protein to the lipid droplet seems to be an important step during lipolytic activation. Re-organization of the

  16. Illudins C2 and C3 stimulate lipolysis in 3T3-L1 adipocytes and suppress adipogenesis in 3T3-L1 preadipocytes.

    PubMed

    Kim, Sun-Ok; Sakchaisri, Krisada; Asami, Yukihiro; Ryoo, In-Ja; Choo, Soo-Jin; Yoo, Ick-Dong; Soung, Nak-Kyun; Kim, Young Sang; Jang, Jae-Hyuk; Kim, Bo Yeon; Ahn, Jong Seog

    2014-04-25

    The secondary metabolites illudins C2 (1) and C3 (2), obtained from the culture broth of Coprinus atramentarius, have been shown to possess antimicrobial activity. In the present study, we discovered novel biological activities of 1 and 2 in lipolysis of differentiated 3T3-L1 adipocytes and adipogenesis of 3T3-L1 preadipocytes. Compounds 1 and 2 exhibit a dose-dependent increase in glycerol release and thereby reduce intracellular lipid accumulation. The stimulatory effects of 1 and 2 on lipolysis are prevented by cAMP-dependent protein kinase (PKA) and extracellular signal-regulated kinase (ERK) inhibitors. Compounds 1 and 2 down-regulated perilipin and also affected the mRNA and protein levels of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). However, 1 and 2 treatment leads to a significant increase in PKA-mediated phosphorylation of HSL at S563 and S660. In addition, 1 and 2 treatment in 3T3-L1 preadipocytes induces down-regulation of the critical transcription factors, CCAAT/enhancer binding protein α and β (C/EBPα and C/EBPβ), and peroxisome proliferator activated receptor γ (PPARγ), which are required for adipogenesis, and accordingly inhibits adipogenesis. These results suggest that 1 and 2 might be useful for treating obesity due to their modulatory effects on fat by affecting adipocyte differentiation and fat mobilization.

  17. Inhibition of Lipolysis in the Novel Transgenic Quail Model Overexpressing G0/G1 Switch Gene 2 in the Adipose Tissue during Feed Restriction

    PubMed Central

    Shin, Sangsu; Choi, Young Min; Han, Jae Yong; Lee, Kichoon

    2014-01-01

    In addition to the issue of obesity in humans, the production of low-fat meat from domestic animals is important in the agricultural industry to satisfy consumer demand. Understanding the regulation of lipolysis in adipose tissue could advance our knowledge to potentially solve both issues. Although the G0/G1 switch gene 2 (G0S2) was recently identified as an inhibitor of adipose triglyceride lipase (ATGL) in vitro, its role in vivo has not been fully clarified. This study was conducted to investigate the role of G0S2 gene in vivo by using two independent transgenic quail lines during different energy conditions. Unexpectedly, G0S2 overexpression had a negligible effect on plasma NEFA concentration, fat cell size and fat pad weight under ad libitum feeding condition when adipose lipolytic activity is minimal. A two-week feed restriction in non-transgenic quail expectedly caused increased plasma NEFA concentration and dramatically reduced fat cell size and fat pad weight. Contrary, G0S2 overexpression under a feed restriction resulted in a significantly less elevation of plasma NEFA concentration and smaller reductions in fat pad weights and fat cell size compared to non-transgenic quail, demonstrating inhibition of lipolysis and resistance to loss of fat by G0S2. Excessive G0S2 inhibits lipolysis in vivo during active lipolytic conditions, such as food restriction and fasting, suggesting G0S2 as a potential target for treatment of obesity. In addition, transgenic quail are novel models for studying lipid metabolism and mechanisms of obesity. PMID:24964090

  18. Effects of local alpha2-adrenergic receptor blockade on adipose tissue lipolysis during prolonged systemic adrenaline infusion in normal man.

    PubMed

    Simonsen, Lene; Enevoldsen, Lotte H; Stallknecht, Bente; Bülow, Jens

    2008-03-01

    During prolonged adrenaline infusion, lipolysis peaks within 30 min and thereafter tends to decline, and we hypothesized that the stimulation of local adipose tissue alpha2-adrenergic receptors accounts for this decline. The lipolytic effect of a prolonged intravenous adrenaline infusion combined with local infusion of the alpha2-blocker phentolamine in superficial and deep abdominal subcutaneous adipose tissue and in preperitoneal adipose tissue was studied in seven healthy subjects. The interstitial glycerol concentration in the three adipose tissue depots was measured by the microdialysis method. Regional adipose tissue blood flow was measured by the (133)Xe clearance technique. Regional glycerol output (lipolytic rate) was calculated from these measurements and simultaneous measurements of arterial glycerol concentrations. Adrenaline infusion increased lipolysis in all three depots (data previously published). Phentolamine infusion did not augment lipolysis in the subcutaneous depots while it increased the lipolytic rate in the preperitoneal depot. It is concluded that alpha2-adrenergic receptors do not have a significant effect on subcutaneous adipose tissue lipolysis during high circulating adrenaline concentrations, and the decrease in lipolysis in subcutaneous adipose tissue under prolonged adrenaline stimulation is thus not attributed to alpha2-adrenergic receptor inhibition of lipolysis. However, in the preperitoneal adipose tissue depot, alpha2-adrenergic receptor tone plays a role for the lipolytic rate obtained during prolonged adrenaline stimulation.

  19. Fat-specific Protein 27 Inhibits Lipolysis by Facilitating the Inhibitory Effect of Transcription Factor Egr1 on Transcription of Adipose Triglyceride Lipase*

    PubMed Central

    Singh, Maneet; Kaur, Rajween; Lee, Mi-Jeong; Pickering, R. Taylor; Sharma, Vishva Mitra; Puri, Vishwajeet; Kandror, Konstantin V.

    2014-01-01

    Lipolysis in fat tissue represents a major source of circulating fatty acids. Previously, we have found that lipolysis in adipocytes is controlled by early growth response transcription factor Egr1 that directly inhibits transcription of adipose triglyceride lipase, ATGL (Chakrabarti, P., Kim, J. Y., Singh, M., Shin, Y. K., Kim, J., Kumbrink, J., Wu, Y., Lee, M. J., Kirsch, K. H., Fried, S. K., and Kandror, K. V. (2013) Mol. Cell. Biol. 33, 3659–3666). Here we demonstrate that knockdown of the lipid droplet protein FSP27 (a.k.a. CIDEC) in human adipocytes increases expression of ATGL at the level of transcription, whereas overexpression of FSP27 has the opposite effect. FSP27 suppresses the activity of the ATGL promoter in vitro, and the proximal Egr1 binding site is responsible for this effect. FSP27 co-immunoprecipitates with Egr1 and increases its association with and inhibition of the ATGL promoter. Knockdown of Egr1 attenuates the inhibitory effect of FSP27. These results provide a new model of transcriptional regulation of ATGL. PMID:24742676

  20. Adipocyte lipolysis and insulin resistance.

    PubMed

    Morigny, Pauline; Houssier, Marianne; Mouisel, Etienne; Langin, Dominique

    2016-06-01

    Obesity-induced insulin resistance is a major risk factor for the development of type 2 diabetes. Basal fat cell lipolysis (i.e., fat cell triacylglycerol breakdown into fatty acids and glycerol in the absence of stimulatory factors) is elevated during obesity and is closely associated with insulin resistance. Inhibition of adipocyte lipolysis may therefore be a promising therapeutic strategy for treating insulin resistance and preventing obesity-associated type 2 diabetes. In this review, we explore the relationship between adipose lipolysis and insulin sensitivity. After providing an overview of the components of fat cell lipolytic machinery, we describe the hypotheses that may support the causality between lipolysis and insulin resistance. Excessive circulating fatty acids may ectopically accumulate in insulin-sensitive tissues and impair insulin action. Increased basal lipolysis may also modify the secretory profile of adipose tissue, influencing whole body insulin sensitivity. Finally, excessive fatty acid release may also worsen adipose tissue inflammation, a well-known parameter contributing to insulin resistance. Partial genetic or pharmacologic inhibition of fat cell lipases in mice as well as short term clinical trials using antilipolytic drugs in humans support the benefit of fat cell lipolysis inhibition on systemic insulin sensitivity and glucose metabolism, which occurs without an increase of fat mass. Modulation of fatty acid fluxes and, putatively, of fat cell secretory pattern may explain the amelioration of insulin sensitivity whereas changes in adipose tissue immune response do not seem involved. Copyright © 2015 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  1. Effect of cyclonicate, a new hypolipemic drug, on lipolysis in vitro.

    PubMed

    Tessari, F; Caparrotta, L; Gaion, R M; Fassina, G

    1981-12-01

    A new hypolipemic drug, cyclonicate (3,3,5-trimethyl-cyclohexyl nicotinate), was studied and its effects were compared with those of nicotinic acid. Experiments were carried out in vitro on rat adipose tissue on spontaneous lipolysis, and on lipolysis stimulated by noradrenaline, theophylline, dibutyryl cyclic AMP. Cyclonicate, like nicotinic acid, reduced the lipolytic stimulation of theophylline. Its effect was dose-dependent but 10 times lower (IC50 = 1 mM) than that of nicotinic acid. The inhibitory activity of both compounds was higher on theophylline-induced lipolysis than on noradrenaline-stimulated lipolysis. Neither one had any effect on dibutyryl cyclic AMP. In the absence of stimulating drugs, cyclonicate increased the FFA/glycerol ratio, more than nicotinic acid. Moreover, cyclonicate inhibited theophylline-induced FFA release much less than glycerol release, while under the same conditions, nicotinic acid inhibited both FFA and glycerol release. Thus cyclonicate would influence not only triglyceride hydrolysis, but also FFA utilization by adipose tissue.

  2. PPARgamma agonism increases rat adipose tissue lipolysis, expression of glyceride lipases, and the response of lipolysis to hormonal control.

    PubMed

    Festuccia, W T; Laplante, M; Berthiaume, M; Gélinas, Y; Deshaies, Y

    2006-10-01

    The aim of this study was to investigate the effect and mechanisms of action of in vivo peroxisome proliferator-activated receptor gamma (PPARgamma) activation on white adipose tissue (WAT) lipolysis and NEFA metabolism. Study rats were treated for 7 days with 15 mg/kg of rosiglitazone per day; control rats were not treated. After a 6-h fast, lipolysis and levels of mRNA for lipases were assessed in explants from various adipose depots. Rosiglitazone markedly increased basal and noradrenaline (norepinephrine)-stimulated glycerol and NEFA release from WAT explants, and amplified their inhibition by insulin. Primary adipocytes isolated from PPARgamma agonist-treated rats were also more responsive to noradrenaline stimulation expressed per cell, ruling out a contribution of an altered number of mature adipocytes in explants. Rosiglitazone concomitantly increased levels of mRNA transcripts for adipose triglyceride lipase (ATGL) and monoglyceride lipase (MGL) in subcutaneous and visceral WAT, and mRNA for hormone-sensitive lipase (HSL) in subcutaneous WAT. Lipase expression increased within 12 h of in vitro exposure of naïve explants to rosiglitazone, suggesting direct transcriptional activation. In parallel, chronic in vivo treatment with rosiglitazone lowered plasma NEFAs and in WAT its expected stimulatory action on glycerol and NEFA recycling, and on the expression of genes involved in NEFA uptake and retention by WAT, such processes counteracting net NEFA export. These findings demonstrate that, in the face of its plasma NEFA-lowering action, PPARgamma agonism stimulates WAT lipolysis, an effect that is compensated by lipid-retaining pathways. The results further suggest that PPARgamma agonism stimulates lipolysis by increasing the lipolytic potential, including the expression levels of the genes encoding adipose triglyceride lipase and monoglyceride lipase.

  3. Acetylshikonin from Zicao Prevents Obesity in Rats on a High-Fat Diet by Inhibiting Lipid Accumulation and Inducing Lipolysis.

    PubMed

    Su, Meiling; Huang, Wendong; Zhu, Banghao

    2016-01-01

    Various drugs have been developed to treat obesity, but these have undesirable secondary effects, and an efficient but non-toxic anti-obesity drug from natural sources is desired. This study investigated the anti-obesity effects and mechanisms of action of acetylshikonin (AS)-which is used in traditional Chinese medicine-in rats on a high-fat diet (HFD). Rats were fed a normal diet or an HFD; the latter group was received no treatment or were treated with 100, 300, or 900 mg/kg AS extract by intragastric administration for 6 weeks. In addition, 3T3-L1 adipocytes were treated with AS and the effects on adipogenesis and lipolysis were evaluated by western blot analysis of adipogenic transcription factors and lipid-metabolizing enzyme levels and the phosphorylation status of protein kinase (PK) A and hormone-sensitive lipase (HSL). AS prevented HFD-induced obesity including reduction in body weight, white adipose tissue content, liver mass, and serum triglyceride and free fatty acid levels in rats. It also suppressed the expression of adipogenic differentiation transcription factors and decreased the expression of the adipocyte-specific proteins HSL and adipose triglyceride lipase (ATGL). Furthermore, AS treatment induced lipolysis, leading to the release of glycerol and increased in PKA and HSL phosphorylation. These findings demonstrate that AS has anti-obesity effects in a rat model and may be a safe treatment for obesity in humans.

  4. Acetylshikonin from Zicao Prevents Obesity in Rats on a High-Fat Diet by Inhibiting Lipid Accumulation and Inducing Lipolysis

    PubMed Central

    Zhu, Banghao

    2016-01-01

    Various drugs have been developed to treat obesity, but these have undesirable secondary effects, and an efficient but non-toxic anti-obesity drug from natural sources is desired. This study investigated the anti-obesity effects and mechanisms of action of acetylshikonin (AS)—which is used in traditional Chinese medicine—in rats on a high-fat diet (HFD). Rats were fed a normal diet or an HFD; the latter group was received no treatment or were treated with 100, 300, or 900 mg/kg AS extract by intragastric administration for 6 weeks. In addition, 3T3-L1 adipocytes were treated with AS and the effects on adipogenesis and lipolysis were evaluated by western blot analysis of adipogenic transcription factors and lipid-metabolizing enzyme levels and the phosphorylation status of protein kinase (PK) A and hormone-sensitive lipase (HSL). AS prevented HFD-induced obesity including reduction in body weight, white adipose tissue content, liver mass, and serum triglyceride and free fatty acid levels in rats. It also suppressed the expression of adipogenic differentiation transcription factors and decreased the expression of the adipocyte-specific proteins HSL and adipose triglyceride lipase (ATGL). Furthermore, AS treatment induced lipolysis, leading to the release of glycerol and increased in PKA and HSL phosphorylation. These findings demonstrate that AS has anti-obesity effects in a rat model and may be a safe treatment for obesity in humans. PMID:26771185

  5. Inhibition of Intracellular Triglyceride Lipolysis Suppresses Cold-Induced Brown Adipose Tissue Metabolism and Increases Shivering in Humans.

    PubMed

    Blondin, Denis P; Frisch, Frédérique; Phoenix, Serge; Guérin, Brigitte; Turcotte, Éric E; Haman, François; Richard, Denis; Carpentier, André C

    2017-02-07

    Indirect evidence from human studies suggests that brown adipose tissue (BAT) thermogenesis is fueled predominantly by fatty acids hydrolyzed from intracellular triglycerides (TGs). However, no direct experimental evidence to support this assumption currently exists in humans. The aim of this study was to determine the role of intracellular TG in BAT thermogenesis, in cold-exposed men. Using positron emission tomography with (11)C-acetate and (18)F-fluorodeoxyglucose, we showed that oral nicotinic acid (NiAc) administration, an inhibitor of intracellular TG lipolysis, suppressed the cold-induced increase in BAT oxidative metabolism and glucose uptake, despite no difference in BAT blood flow. There was a commensurate increase in shivering intensity and shift toward a greater reliance on glycolytic muscle fibers without modifying total heat production. Together, these findings show that intracellular TG lipolysis is critical for BAT thermogenesis and provides experimental evidence for a reciprocal role of BAT thermogenesis and shivering in cold-induced thermogenesis in humans. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Lipid droplet meets a mitochondrial protein to regulate adipocyte lipolysis

    USDA-ARS?s Scientific Manuscript database

    In response to adrenergic stimulation, adipocytes undergo protein kinase A (PKA)-stimulated lipolysis. A key PKA target in this context is perilipin 1, a major regulator of lipolysis on lipid droplets (LDs). A study published in this issue of The EMBO Journal (Pidoux et al, 2011) identifies optic at...

  7. Tauroursodeoxycholic acid inhibits TNF-α-induced lipolysis in 3T3-L1 adipocytes via the IRE-JNK-perilipin-A signaling pathway.

    PubMed

    Xia, Wenyan; Zhou, Yu; Wang, Lijing; Wang, Linxi; Liu, Xiaoying; Lin, Yichuan; Zhou, Qing; Huang, Jianqing; Liu, Libin

    2017-04-01

    The present study investigated the effects of tauroursodeoxycholic acid (TUDCA) on the lipolytic action of tumor necrosis factor (TNF)-α in 3T3-L1 adipocytes. Following treatment with TNF‑α, cell viability was determined by MTT assay to select the optimum concentration and duration of TNF‑α treatment in 3T3‑L1 adipocytes. Intracellular lipid droplet dispersion and glycerin content in culture media were determined to evaluate the effect of TUDCA on TNF‑α‑induced lipolysis in 3T3‑L1 adipocytes. Western blotting was performed to detect protein expression levels of perilipin‑A and protein markers of endoplasmic reticulum stress: Immunoglobulin‑binding protein (BiP), inositol‑requiring enzyme (IRE), c‑Jun N‑terminal kinase (JNK), phosphorylated (p)‑IRE and p‑JNK. Following treatment with 50 ng/ml TNF‑α for 24 h, glycerin content increased significantly and lipid droplets were dispersed. Glycerin content was reduced significantly and dispersal of lipid droplets reduced following pretreatment of 3T3‑L1 adipocytes with 1 mmol/l TUDCA. TNF‑α additionally activated the expression of BiP, p‑IRE and p‑JNK in a time‑dependent manner; following pretreatment of 3T3‑L1 adipocytes with 1 mmol/l TUDCA, the expression levels of these three proteins decreased. Therefore, TUDCA may inhibit TNF-α-induced lipolysis in 3T3‑L1 adipocytes and reduce production of free fatty acids. Its underlying molecular mechanisms are potentially associated with the inhibition of activation of the IRE‑JNK signaling pathway, which influences perilipin-A expression levels.

  8. Transcranial magnetic stimulation (TMS) inhibits cortical dendrites.

    PubMed

    Murphy, Sean C; Palmer, Lucy M; Nyffeler, Thomas; Müri, René M; Larkum, Matthew E

    2016-03-18

    One of the leading approaches to non-invasively treat a variety of brain disorders is transcranial magnetic stimulation (TMS). However, despite its clinical prevalence, very little is known about the action of TMS at the cellular level let alone what effect it might have at the subcellular level (e.g. dendrites). Here, we examine the effect of single-pulse TMS on dendritic activity in layer 5 pyramidal neurons of the somatosensory cortex using an optical fiber imaging approach. We find that TMS causes GABAB-mediated inhibition of sensory-evoked dendritic Ca(2+) activity. We conclude that TMS directly activates fibers within the upper cortical layers that leads to the activation of dendrite-targeting inhibitory neurons which in turn suppress dendritic Ca(2+) activity. This result implies a specificity of TMS at the dendritic level that could in principle be exploited for investigating these structures non-invasively.

  9. Trichostatin A modulates thiazolidinedione-mediated suppression of tumor necrosis factor α-induced lipolysis in 3T3-L1 adipocytes.

    PubMed

    Lu, Juu-Chin; Chang, Yu-Tzu; Wang, Chih-Tien; Lin, Yu-Chun; Lin, Chun-Ken; Wu, Zhong-Sheng

    2013-01-01

    In obesity, high levels of tumor necrosis factor α (TNFα) stimulate lipolysis in adipocytes, leading to hyperlipidemia and insulin resistance. Thiazolidinediones (TZDs), the insulin-sensitizing drugs, antagonize TNFα-induced lipolysis in adipocytes, thereby increasing insulin sensitivity in diabetes patients. The cellular target of TZDs is peroxisome proliferator-activated receptor γ (PPARγ), a nuclear receptor that controls many adipocyte functions. As a transcription factor, PPARγ is closely modulated by coregulators, which include coactivators and corepressors. Previous studies have revealed that in macrophages, the insulin-sensitizing effect of PPARγ may involve suppression of proinflammatory gene expression by recruiting the corepressor complex that contains corepressors and histone deacetylases (HDACs). Therefore, we investigated whether the corepressor complex is involved in TZD-mediated suppression of TNFα-induced lipolysis in 3T3-L1 adipocytes. Trichostatin A (TSA), a pan HDAC inhibitor (HDACI) that inhibits class I and II HDACs, was used to examine the involvement of HDACs in the actions of TZDs. TSA alone increased basal lipolysis and attenuated TZD-mediated suppression of TNFα-induced lipolysis. Increased basal lipolysis may in part result from class I HDAC inhibition because selective class I HDACI treatment had similar results. However, attenuation of TZD-mediated TNFα antagonism may be specific to TSA and related hydroxamate-based HDACI rather than to HDAC inhibition. Consistently, corepressor depletion did not affect TZD-mediated suppression. Interestingly, TSA treatment greatly reduced PPARγ levels in differentiated adipocytes. Finally, extracellular signal-related kinase 1/2 (ERK1/2) mediated TNFα-induced lipolysis, and TZDs suppressed TNFα-induced ERK phosphorylation. We determined that TSA increased basal ERK phosphorylation, and attenuated TZD-mediated suppression of TNFα-induced ERK phosphorylation, consistent with TSA's effects

  10. Trichostatin A Modulates Thiazolidinedione-Mediated Suppression of Tumor Necrosis Factor α-Induced Lipolysis in 3T3-L1 Adipocytes

    PubMed Central

    Lu, Juu-Chin; Chang, Yu-Tzu; Wang, Chih-Tien; Lin, Yu-Chun; Lin, Chun-Ken; Wu, Zhong-Sheng

    2013-01-01

    In obesity, high levels of tumor necrosis factor α (TNFα) stimulate lipolysis in adipocytes, leading to hyperlipidemia and insulin resistance. Thiazolidinediones (TZDs), the insulin-sensitizing drugs, antagonize TNFα-induced lipolysis in adipocytes, thereby increasing insulin sensitivity in diabetes patients. The cellular target of TZDs is peroxisome proliferator-activated receptor γ (PPARγ), a nuclear receptor that controls many adipocyte functions. As a transcription factor, PPARγ is closely modulated by coregulators, which include coactivators and corepressors. Previous studies have revealed that in macrophages, the insulin-sensitizing effect of PPARγ may involve suppression of proinflammatory gene expression by recruiting the corepressor complex that contains corepressors and histone deacetylases (HDACs). Therefore, we investigated whether the corepressor complex is involved in TZD-mediated suppression of TNFα-induced lipolysis in 3T3-L1 adipocytes. Trichostatin A (TSA), a pan HDAC inhibitor (HDACI) that inhibits class I and II HDACs, was used to examine the involvement of HDACs in the actions of TZDs. TSA alone increased basal lipolysis and attenuated TZD-mediated suppression of TNFα-induced lipolysis. Increased basal lipolysis may in part result from class I HDAC inhibition because selective class I HDACI treatment had similar results. However, attenuation of TZD-mediated TNFα antagonism may be specific to TSA and related hydroxamate-based HDACI rather than to HDAC inhibition. Consistently, corepressor depletion did not affect TZD-mediated suppression. Interestingly, TSA treatment greatly reduced PPARγ levels in differentiated adipocytes. Finally, extracellular signal-related kinase 1/2 (ERK1/2) mediated TNFα-induced lipolysis, and TZDs suppressed TNFα-induced ERK phosphorylation. We determined that TSA increased basal ERK phosphorylation, and attenuated TZD-mediated suppression of TNFα-induced ERK phosphorylation, consistent with TSA

  11. Platyphylloside Isolated From Betula platyphylla Inhibit Adipocyte Differentiation and Induce Lipolysis Via Regulating Adipokines Including PPARγ in 3T3-L1 Cells.

    PubMed

    Lee, Mina; Sung, Sang Hyun

    2016-01-01

    Obesity causes or aggravates many health problems, both independently and in association with several pathological disorders, including Type II diabetes, hypertension, atherosclerosis, and cancer. Therefore, we screened small compounds isolated from natural products for the development of anti-obesity drugs. The purpose of this study was to investigate the anti-adipogenic activities of platyphylloside, diarylheptanoid isolated from Betula platyphylla, which was selected based on the screening using 3T3-L1 cells. To evaluate the inhibition of adipocyte differentiation and lipolysis, lipid contents of BPP on were measured using Oil Red O staining in 3T3-L1 cells. The mRNA and protein expression levels of various adipokines were measured by Quantitative real-time PCR and Western blotting analysis, respectively. Platyphylloside showed significant inhibitory activity on adipocyte differentiation in 3T3-L1 cells and suppressed adipocyte differentiation even in the presence of troglitazone, a PPARγ agonist. Platyphylloside might suppress adipocyte differentiation through PPARγ, C/EBPα, and SREBP1-induced adipogenesis, which is synergistically associated with downstream adipocyte-specific gene promoters such as aP2, FAS, SCD-1, LPL, and Adiponectin. In addition, platyphylloside affected lipolysis by down-regulating perilipin and HSL and up-regulating TNFα. Taken together, the results reveal that platyphylloside has anti-adipogenic activity and highlight its potential in the prevention and treatment of obesity. The extract of B. platyphylla bark and its isolate, BPP, had anti-adipogenic activity in 3T3-L1 cells via suppression of adipocyte differentiation from preadipocytes.Treatment with BPP significantly down-regulated the expression of PPARγ, C/EBP, C/EBPβ, C/EBPδ, SREBP1c, SCD-1, FAS, aP2 and LPL.BPP induced a lipolytic response in mature adipocytes via up-regulation krof TNFá and down-regulation of HSL, perilipin, PPARγ, PDE3B, and Gia1.BPP is a novel

  12. [Adipose triglyceride lipase regulates adipocyte lipolysis].

    PubMed

    Xu, Chong; Xu, Guo-Heng

    2008-01-01

    Obesity, insulin resistance, and type 2 diabetes are associated with elevated concentration of circulating free fatty acids (FFAs), which are critically governed by the process of triglyceride lipolysis in adipocytes. Hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) are two major enzymes in the control of triacylglycerol hydrolysis in adipose tissue. ATGL expressed predominantly in white adipose tissue specifically initiates triacylglycerol hydrolysis to generate diacylglycerols and FFA, a role distinguished from HSL that mainly hydrolyzes diacylglycerols. The transcription of ATGL is regulated by several factors. ATGL activity is regulated by CGI-58. Under basal conditions, interaction of CGI-58 with a lipid droplet associating protein, perilipin, results in an inactivation of ATGL activity. During PKA-stimulated lipolysis, CGI-58 is released from phosphorylated perilipin and in turn, binds to ATGL. This action facilitates triglyceride lipolysis. This review focuses on the regulation and function of ATGL in adipose lipolysis and metabolism.

  13. Transcranial magnetic stimulation (TMS) inhibits cortical dendrites

    PubMed Central

    Murphy, Sean C; Palmer, Lucy M; Nyffeler, Thomas; Müri, René M; Larkum, Matthew E

    2016-01-01

    One of the leading approaches to non-invasively treat a variety of brain disorders is transcranial magnetic stimulation (TMS). However, despite its clinical prevalence, very little is known about the action of TMS at the cellular level let alone what effect it might have at the subcellular level (e.g. dendrites). Here, we examine the effect of single-pulse TMS on dendritic activity in layer 5 pyramidal neurons of the somatosensory cortex using an optical fiber imaging approach. We find that TMS causes GABAB-mediated inhibition of sensory-evoked dendritic Ca2+ activity. We conclude that TMS directly activates fibers within the upper cortical layers that leads to the activation of dendrite-targeting inhibitory neurons which in turn suppress dendritic Ca2+ activity. This result implies a specificity of TMS at the dendritic level that could in principle be exploited for investigating these structures non-invasively. DOI: http://dx.doi.org/10.7554/eLife.13598.001 PMID:26988796

  14. Novel pharmacological probes reveal ABHD5 as a locus of lipolysis control in white and brown adipocytes.

    PubMed

    Rondini, Elizabeth A; Mladenovic-Lucas, Ljiljana; Roush, William R; Halvorsen, Geoff; Green, Alex E; Granneman, James G

    2017-09-19

    Current knowledge regarding acute regulation of adipocyte lipolysis is largely based on receptor-mediated activation or inhibition of pathways that influence intracellular levels of cyclic AMP (cAMP), thereby affecting protein kinase A (PKA) activity. We recently identified synthetic ligands of α-β-hydrolase domain containing 5 (ABHD5) that directly activate adipose triglyceride lipase (ATGL) by dissociating ABHD5 from its inhibitory regulator, perilipin-1 (PLIN1). In the current study we used these novel ligands to determine the direct contribution of ABHD5 to various aspects of lipolysis control in white (3T3-L1) and brown adipocytes. ABHD5 ligands stimulated adipocyte lipolysis without affecting PKA-dependent phosphorylation on consensus sites of PLIN1 or HSL. Co-treatment of adipocytes with synthetic ABHD5 ligands did not alter the potency or maximal lipolysis efficacy of the β-adrenergic receptor (ADRB) agonist, isoproterenol, indicating both target a common pool of ABHD5. Reducing ADRB/PKA signaling with insulin or desensitizing ADRB suppressed lipolysis responses to a subsequent challenge with ISO, but not to ABHD5 ligands. Lastly, despite strong treatment differences in PKA-dependent phosphorylation of hormone sensitive lipase (HSL), we found that ligand-mediated activation of ABHD5 led to complete TG hydrolysis, which involved predominately ATGL, but also HSL. These results indicate that the overall pattern of lipolysis controlled by ABHD5 ligands is similar to that of isoproterenol and that ABHD5 plays a central role in the regulation of adipocyte lipolysis. As lipolysis is critical for adaptive thermogenesis and in catabolic tissue remodeling, ABHD5 ligands may provide a means of activating these processes under conditions where receptor signaling is compromised. The American Society for Pharmacology and Experimental Therapeutics.

  15. Leucine Deprivation Decreases Fat Mass by Stimulation of Lipolysis in White Adipose Tissue and Upregulation of Uncoupling Protein 1 (UCP1) in Brown Adipose Tissue

    PubMed Central

    Cheng, Ying; Meng, Qingshu; Wang, Chunxia; Li, Houkai; Huang, Zhiying; Chen, Shanghai; Xiao, Fei; Guo, Feifan

    2010-01-01

    OBJECTIVE White adipose tissue (WAT) and brown adipose tissue (BAT) play distinct roles in adaptation to changes in nutrient availability, with WAT serving as an energy store and BAT regulating thermogenesis. We previously showed that mice maintained on a leucine-deficient diet unexpectedly experienced a dramatic reduction in abdominal fat mass. The cellular mechanisms responsible for this loss, however, are unclear. The goal of current study is to investigate possible mechanisms. RESEARCH DESIGN AND METHODS Male C57BL/6J mice were fed either control, leucine-deficient, or pair-fed diets for 7 days. Changes in metabolic parameters and expression of genes and proteins related to lipid metabolism were analyzed in WAT and BAT. RESULTS We found that leucine deprivation for 7 days increases oxygen consumption, suggesting increased energy expenditure. We also observed increases in lipolysis and expression of β-oxidation genes and decreases in expression of lipogenic genes and activity of fatty acid synthase in WAT, consistent with increased use and decreased synthesis of fatty acids, respectively. Furthermore, we observed that leucine deprivation increases expression of uncoupling protein (UCP)-1 in BAT, suggesting increased thermogenesis. CONCLUSIONS We show for the first time that elimination of dietary leucine produces significant metabolic changes in WAT and BAT. The effect of leucine deprivation on UCP1 expression is a novel and unexpected observation and suggests that the observed increase in energy expenditure may reflect an increase in thermogenesis in BAT. Further investigation will be required to determine the relative contribution of UCP1 upregulation and thermogenesis in BAT to leucine deprivation-stimulated fat loss. PMID:19833890

  16. Fatty acids from fat cell lipolysis do not activate an inflammatory response but are stored as triacylglycerols in adipose tissue macrophages.

    PubMed

    Caspar-Bauguil, Sylvie; Kolditz, Catherine-Ines; Lefort, Corinne; Vila, Isabelle; Mouisel, Etienne; Beuzelin, Diane; Tavernier, Geneviève; Marques, Marie-Adeline; Zakaroff-Girard, Alexia; Pecher, Christiane; Houssier, Marianne; Mir, Lucile; Nicolas, Sarah; Moro, Cédric; Langin, Dominique

    2015-11-01

    Activation of macrophages by fatty acids (FAs) is a potential mechanism linking obesity to adipose tissue (AT) inflammation and insulin resistance. Here, we investigated the effects of FAs released during adipocyte lipolysis on AT macrophages (ATMs). Human THP-1 macrophages were treated with media from human multipotent adipose-derived stem (hMADS) adipocytes stimulated with lipolytic drugs. Macrophages were also treated with mixtures of FAs and an inhibitor of Toll-like receptor 4, since this receptor is activated by saturated FAs. Levels of mRNA and the secretion of inflammation-related molecules were measured in macrophages. FA composition was determined in adipocytes, conditioned media and macrophages. The effect of chronic inhibition or acute activation of fat cell lipolysis on ATM response was investigated in vivo in mice. Whereas palmitic acid alone activates THP-1, conditioned media from hMADS adipocyte lipolysis had no effect on IL, chemokine and cytokine gene expression, and secretion by macrophages. Mixtures of FAs representing de novo lipogenesis or habitual dietary conditions also had no effect. FAs derived from adipocyte lipolysis were taken up by macrophages and stored as triacylglycerol droplets. In vivo, chronic treatment with an antilipolytic drug did not modify gene expression and number of ATMs in mice with intact or defective Tlr4. Stimulation of adipocyte lipolysis increased storage of neutral lipids by macrophages without change in number and phenotype. Our data suggest that adipocyte lipolysis does not activate inflammatory pathways in ATMs, which instead may act as scavengers of FAs.

  17. Fat-specific Protein 27 (FSP27) Interacts with Adipose Triglyceride Lipase (ATGL) to Regulate Lipolysis and Insulin Sensitivity in Human Adipocytes*

    PubMed Central

    Grahn, Tan Hooi Min; Kaur, Rajween; Yin, Jun; Schweiger, Martina; Sharma, Vishva Mitra; Lee, Mi-Jeong; Ido, Yasuo; Smas, Cynthia M.; Zechner, Rudolf; Lass, Achim; Puri, Vishwajeet

    2014-01-01

    In adipocytes, lipolysis is a highly regulated process involving hormonal signals, lipid droplet-associated proteins, and lipases. The discovery of new lipid droplet-associated proteins added complexity to the current model of lipolysis. In this study, we used cultured human adipocytes to demonstrate that fat-specific protein 27 (FSP27), an abundantly expressed protein in adipocytes, regulates both basal and stimulated lipolysis by interacting with adipose triglyceride lipase (ATGL, also called desnutrin or PNPLA2). We identified a core domain of FSP27, amino acids 120–220, that interacts with ATGL to inhibit its lipolytic function and promote triglyceride storage. We also defined the role of FSP27 in free fatty acid-induced insulin resistance in adipocytes. FSP27 depletion in human adipocytes increased lipolysis and inhibited insulin signaling by decreasing AKT phosphorylation. However, reducing lipolysis by either depletion of ATGL or expression of exogenous full-length FSP27 or amino acids 120–220 protected human adipocytes against the adverse effects of free fatty acids on insulin signaling. In embryonic fibroblasts derived from ATGL KO mice, exogenous free fatty acids did not affect insulin sensitivity. Our results demonstrate a crucial role for FSP27-ATGL interactions in regulating lipolysis, triglyceride accumulation, and insulin signaling in human adipocytes. PMID:24627478

  18. Fat-specific protein 27 (FSP27) interacts with adipose triglyceride lipase (ATGL) to regulate lipolysis and insulin sensitivity in human adipocytes.

    PubMed

    Grahn, Tan Hooi Min; Kaur, Rajween; Yin, Jun; Schweiger, Martina; Sharma, Vishva Mitra; Lee, Mi-Jeong; Ido, Yasuo; Smas, Cynthia M; Zechner, Rudolf; Lass, Achim; Puri, Vishwajeet

    2014-04-25

    In adipocytes, lipolysis is a highly regulated process involving hormonal signals, lipid droplet-associated proteins, and lipases. The discovery of new lipid droplet-associated proteins added complexity to the current model of lipolysis. In this study, we used cultured human adipocytes to demonstrate that fat-specific protein 27 (FSP27), an abundantly expressed protein in adipocytes, regulates both basal and stimulated lipolysis by interacting with adipose triglyceride lipase (ATGL, also called desnutrin or PNPLA2). We identified a core domain of FSP27, amino acids 120-220, that interacts with ATGL to inhibit its lipolytic function and promote triglyceride storage. We also defined the role of FSP27 in free fatty acid-induced insulin resistance in adipocytes. FSP27 depletion in human adipocytes increased lipolysis and inhibited insulin signaling by decreasing AKT phosphorylation. However, reducing lipolysis by either depletion of ATGL or expression of exogenous full-length FSP27 or amino acids 120-220 protected human adipocytes against the adverse effects of free fatty acids on insulin signaling. In embryonic fibroblasts derived from ATGL KO mice, exogenous free fatty acids did not affect insulin sensitivity. Our results demonstrate a crucial role for FSP27-ATGL interactions in regulating lipolysis, triglyceride accumulation, and insulin signaling in human adipocytes.

  19. Activation of G protein-coupled receptor 43 in adipocytes leads to inhibition of lipolysis and suppression of plasma free fatty acids.

    PubMed

    Ge, Hongfei; Li, Xiaofan; Weiszmann, Jennifer; Wang, Ping; Baribault, Helene; Chen, Jin-Long; Tian, Hui; Li, Yang

    2008-09-01

    G protein-coupled receptor 43 (GPR43) has been identified as a receptor for short-chain fatty acids that include acetate and propionate. A potential involvement of GPR43 in immune and inflammatory response has been previously suggested because its expression is highly enriched in immune cells. GPR43 is also expressed in a number of other tissues including adipocytes; however, the functional consequences of GPR43 activation in these other tissues are not clear. In this report, we focus on the potential functions of GPR43 in adipocytes. We show that adipocytes treated with GPR43 natural ligands, acetate and propionate, exhibit a reduction in lipolytic activity. This inhibition of lipolysis is the result of GPR43 activation, because this effect is abolished in adipocytes isolated from GPR43 knockout animals. In a mouse in vivo model, we show that the activation of GPR43 by acetate results in the reduction in plasma free fatty acid levels without inducing the flushing side effect that has been observed by the activation of nicotinic acid receptor, GPR109A. These results suggest a potential role for GPR43 in regulating plasma lipid profiles and perhaps aspects of metabolic syndrome.

  20. Platyphylloside Isolated From Betula platyphylla Inhibit Adipocyte Differentiation and Induce Lipolysis Via Regulating Adipokines Including PPARγ in 3T3-L1 Cells

    PubMed Central

    Lee, Mina; Sung, Sang Hyun

    2016-01-01

    Background: Obesity causes or aggravates many health problems, both independently and in association with several pathological disorders, including Type II diabetes, hypertension, atherosclerosis, and cancer. Therefore, we screened small compounds isolated from natural products for the development of anti-obesity drugs. Objective: The purpose of this study was to investigate the anti-adipogenic activities of platyphylloside, diarylheptanoid isolated from Betula platyphylla, which was selected based on the screening using 3T3-L1 cells. Materials and Methods: To evaluate the inhibition of adipocyte differentiation and lipolysis, lipid contents of BPP on were measured using Oil Red O staining in 3T3-L1 cells. The mRNA and protein expression levels of various adipokines were measured by Quantitative real-time PCR and Western blotting analysis, respectively. Results: Platyphylloside showed significant inhibitory activity on adipocyte differentiation in 3T3-L1 cells and suppressed adipocyte differentiation even in the presence of troglitazone, a PPARγ agonist. Platyphylloside might suppress adipocyte differentiation through PPARγ, C/EBPα, and SREBP1-induced adipogenesis, which is synergistically associated with downstream adipocyte-specific gene promoters such as aP2, FAS, SCD-1, LPL, and Adiponectin. In addition, platyphylloside affected lipolysis by down-regulating perilipin and HSL and up-regulating TNFα. Conclusion: Taken together, the results reveal that platyphylloside has anti-adipogenic activity and highlight its potential in the prevention and treatment of obesity. SUMMARY The extract of B. platyphylla bark and its isolate, BPP, had anti-adipogenic activity in 3T3-L1 cells via suppression of adipocyte differentiation from preadipocytes.Treatment with BPP significantly down-regulated the expression of PPARγ, C/EBP, C/EBPβ, C/EBPδ, SREBP1c, SCD-1, FAS, aP2 and LPL.BPP induced a lipolytic response in mature adipocytes via up-regulation krof TNFá and down

  1. Conjugated linoleic acid supplementation caused reduction of perilipin1 and aberrant lipolysis in epididymal adipose tissue

    SciTech Connect

    Cai, Demin; Li, Hongji; Zhou, Bo; Han, Liqiang; Zhang, Xiaomei; Yang, Guoyu; Yang, Guoqing

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer Conjugated linoleic acid supplementation suppresses perilipin1 in epididymal fat. Black-Right-Pointing-Pointer Conjugated linoleic acid inhibits promoter activity of perilipin1 in 3T3-L1 cells. Black-Right-Pointing-Pointer Conjugated linoleic acids elevate basal but blunt hormone-stimulated lipolysis. -- Abstract: Perilipin1, a coat protein of lipid droplet, plays a key role in adipocyte lipolysis and fat formation of adipose tissues. However, it is not clear how the expression of perilipin1 is affected in the decreased white adipose tissues (WAT) of mice treated with dietary supplement of conjugated linoleic acids (CLA). Here we obtained lipodystrophic mice by dietary administration of CLA which exhibited reduced epididymal (EPI) WAT, aberrant adipocytes and decreased expression of leptin in this tissue. We found both transcription and translation of perilipin1 was suppressed significantly in EPI WAT of CLA-treated mice compared to that of control mice. The gene expression of negative regulator tumor necrosis factor {alpha} (TNF{alpha}) and the positive regulator Peroxisome Proliferator-Activated Receptor-{gamma} (PPAR{gamma}) of perilipin1 was up-regulated and down-regulated, respectively. In cultured 3T3-L1 cells the promoter activity of perilipin1 was dramatically inhibited in the presence of CLA. Using ex vivo experiment we found that the basal lipolysis was elevated but the hormone-stimulated lipolysis blunted in adipose explants of CLA-treated mice compared to that of control mice, suggesting that the reduction of perilipin1 in white adipose tissues may at least in part contribute to CLA-mediated alternation of lipolysis of WAT.

  2. Can intraurethral stimulation inhibit micturition reflex in normal female rats?

    PubMed Central

    Yu, Tian; Liao, Limin; Wyndaele, Jean Jacques

    2016-01-01

    ABSTRACT Objective The study was designed to determine the effect of low frequency (2.5Hz) intraurethral electrical stimulation on bladder capacity and maximum voiding pressures. Materials and Methods The experiments were conducted in 15 virgin female Sprague-Dawley rats (220–250g). The animals were anesthetized by intraperitoneal injection of urethane (1.5g/kg). Animal care and experimental procedures were reviewed and approved by the Institutional Animal Care and Use Committee of Antwerp University (code: 2013-50). Unipolar square pulses of 0.06mA were used to stimulate urethra at frequency of 2.5Hz (0.2ms pulse width) in order to evaluate the ability of intraurethral stimulation to inhibit bladder contractions. Continuous stimulation and intermittent stimulation with 5sec ‘‘on’’ and 5sec ‘‘off’’ duty cycle were applied during repeated saline cystometrograms (CMGs). Maximum voiding pressures (MVP) and bladder capacity were investigated to determine the inhibitory effect on bladder contraction induced by intraurethral stimulation. Results The continuous stimulation and intermittent stimulation significantly (p<0.05) decreased MVP and increased bladder capacity. There was no significant difference in MVP and bladder capacity between continuous and intermittent stimulation group. Conclusions The present results suggest that 2.5Hz continuous and intermittent intraurethral stimulation can inhibit micturition reflex, decrease MVP and increase bladder capacity. There was no significant difference in MVP and bladder capacity between continuous and intermittent stimulation group. PMID:27286128

  3. Effect of insulin, the glutathione system, and superoxide anion radical in modulation of lipolysis in adipocytes of rats with experimental diabetes.

    PubMed

    Ivanov, V V; Shakhristova, E V; Stepovaya, E A; Nosareva, O L; Fedorova, T S; Ryazantseva, N V; Novitsky, V V

    2015-01-01

    Spontaneous lipolysis was found to be increased in adipocytes of rats with alloxan-induced diabetes. In addition, isoproterenol-stimulated hydrolysis of triacylglycerols was inhibited against the background of oxidative stress and decreased redox-status of cells. A decrease in the ability of insulin to inhibit isoproterenol-stimulated lipolysis in adipocytes that were isolated from adipose tissue of rats with experimental diabetes was found, which shows a disorder in regulation of lipolysis in adipocytes by the hormone in alloxan-induced diabetes. Based on these findings, we concluded that there is an influence of reactive oxygen species, superoxide anion radical in particular, and redox potential of the glutathione system on molecular mechanisms of change in lipolysis intensity in rat adipocytes in alloxan-induced oxidative stress. Activation of spontaneous lipolysis under conditions of oxidative stress might be a reason for the high concentration of free fatty acids in blood plasma in experimental diabetes, and this may play a significant role in development of insulin resistance and appearance of complications of diabetes.

  4. Mathematical modeling of laser lipolysis

    PubMed Central

    Mordon, Serge R; Wassmer, Benjamin; Reynaud, Jean Pascal; Zemmouri, Jaouad

    2008-01-01

    energy, typically 5 cm3 for 3000 J. At last, skin retraction was observed in patients at 6-month follow up. This observation can be easily explained by mathematical modeling showing that the temperature increase inside the lower dermis is sufficient (48–50°C) to induce skin tightening Discussion and Conclusion Laser lipolysis can be described by a theoretical model. Fat volume reduction observed in patients is in accordance with model calculations. Due to heat diffusion, temperature elevation is also produced inside the lower reticular dermis. This interesting observation can explain remodeling of the collagenous tissue, with clinically evident skin tightening. In conclusion, while the heat generated by interstitial laser irradiation provides stimulate lipolysis of the fat cells, the collagen and elastin are also stimulated resulting in a tightening in the skin. This mathematical model should serve as a useful tool to simulate and better understand the mechanism of action of the laser lipolysis PMID:18312643

  5. Mathematical modeling of laser lipolysis.

    PubMed

    Mordon, Serge R; Wassmer, Benjamin; Reynaud, Jean Pascal; Zemmouri, Jaouad

    2008-02-29

    was observed in patients at 6-month follow up. This observation can be easily explained by mathematical modeling showing that the temperature increase inside the lower dermis is sufficient (48-50 degrees C) to induce skin tightening Laser lipolysis can be described by a theoretical model. Fat volume reduction observed in patients is in accordance with model calculations. Due to heat diffusion, temperature elevation is also produced inside the lower reticular dermis. This interesting observation can explain remodeling of the collagenous tissue, with clinically evident skin tightening. In conclusion, while the heat generated by interstitial laser irradiation provides stimulate lipolysis of the fat cells, the collagen and elastin are also stimulated resulting in a tightening in the skin. This mathematical model should serve as a useful tool to simulate and better understand the mechanism of action of the laser lipolysis.

  6. Phosphatidic acid inhibits ceramide 1-phosphate-stimulated macrophage migration.

    PubMed

    Ouro, Alberto; Arana, Lide; Rivera, Io-Guané; Ordoñez, Marta; Gomez-Larrauri, Ana; Presa, Natalia; Simón, Jorge; Trueba, Miguel; Gangoiti, Patricia; Bittman, Robert; Gomez-Muñoz, Antonio

    2014-12-15

    Ceramide 1-phosphate (C1P) was recently demonstrated to potently induce cell migration. This action could only be observed when C1P was applied exogenously to cells in culture, and was inhibited by pertussis toxin. However, the mechanisms involved in this process are poorly understood. In this work, we found that phosphatidic acid (PA), which is structurally related to C1P, displaced radiolabeled C1P from its membrane-binding site and inhibited C1P-stimulated macrophage migration. This effect was independent of the saturated fatty acid chain length or the presence of a double bond in each of the fatty acyl chains of PA. Treatment of RAW264.7 macrophages with exogenous phospholipase D (PLD), an enzyme that produces PA from membrane phospholipids, also inhibited C1P-stimulated cell migration. Likewise, PA or exogenous PLD inhibited C1P-stimulated extracellularly regulated kinases (ERK) 1 and 2 phosphorylation, leading to inhibition of cell migration. However, PA did not inhibit C1P-stimulated Akt phosphorylation. It is concluded that PA is a physiological regulator of C1P-stimulated macrophage migration. These actions of PA may have important implications in the control of pathophysiological functions that are regulated by C1P, including inflammation and various cellular processes associated with cell migration such as organogenesis or tumor metastasis.

  7. Regulation of adipose tissue lipolysis revisited.

    PubMed

    Bézaire, Véronic; Langin, Dominique

    2009-11-01

    Human obesity and its complications are an increasing burden in developed and underdeveloped countries. Adipose tissue mass and the mechanisms that control it are central to elucidating the aetiology of obesity and insulin resistance. Over the past 15 years tremendous progress has been made in several avenues relating to adipose tissue. Knowledge of the lipolytic machinery has grown with the identification of new lipases, cofactors and interactions between proteins and lipids that are central to the regulation of basal and stimulated lipolysis. The dated idea of an inert lipid droplet has been appropriately revamped to that of a dynamic and highly-structured organelle that in itself offers regulatory control over lipolysis. The present review provides an overview of the numerous partners and pathways involved in adipose tissue lipolysis and their interaction under various metabolic states. Integration of these findings into whole adipose tissue metabolism and its systemic effects is also presented in the context of inflammation and insulin resistance.

  8. Measurement of lipolysis.

    PubMed

    Schweiger, Martina; Eichmann, Thomas O; Taschler, Ulrike; Zimmermann, Robert; Zechner, Rudolf; Lass, Achim

    2014-01-01

    Lipolysis is defined as the hydrolytic cleavage of ester bonds in triglycerides (TGs), resulting in the generation of fatty acids (FAs) and glycerol. The two major TG pools in the body of vertebrates comprise intracellular TGs and plasma/nutritional TGs. Accordingly, this leads to the discrimination between intracellular and intravascular/gastrointestinal lipolysis, respectively. This chapter focuses exclusively on intracellular lipolysis, referred to as lipolysis herein. The lipolytic cleavage of TGs occurs in essentially all cells and tissues of the body. In all of them, the resulting FAs are utilized endogenously for energy production or biosynthetic pathways with one exception, white adipose tissue (WAT). WAT releases FAs and glycerol to supply nonadipose tissues at times of nutrient deprivation. The fundamental role of lipolysis in lipid and energy homeostasis requires the accurate measurement of lipase activities and lipolytic rates. The recent discovery of new enzymes and regulators that mediate the hydrolysis of TG has made these measurements more complex. Here, we describe detailed methodology for how to measure lipolysis and specific enzymes' activities in cells, organs, and their respective extracts. © 2014 Elsevier Inc. All rights reserved.

  9. Measurement of Lipolysis

    PubMed Central

    Schweiger, Martina; Eichmann, Thomas O.; Taschler, Ulrike; Zimmermann, Robert; Zechner, Rudolf; Lass, Achim

    2014-01-01

    Lipolysis is defined as the hydrolytic cleavage of ester bonds in triglycerides (TGs), resulting in the generation of fatty acids (FAs) and glycerol. The two major TG pools in the body of vertebrates comprise intracellular TGs and plasma/nutritional TGs. Accordingly, this leads to the discrimination between intracellular and intravascular/gastrointestinal lipolysis, respectively. This chapter focuses exclusively on intracellular lipolysis, referred to as lipolysis herein. The lipolytic cleavage of TGs occurs in essentially all cells and tissues of the body. In all of them, the resulting FAs are utilized endogenously for energy production or biosynthetic pathways with one exception, white adipose tissue (WAT). WAT releases FAs and glycerol to supply nonadipose tissues at times of nutrient deprivation. The fundamental role of lipolysis in lipid and energy homeostasis requires the accurate measurement of lipase activities and lipolytic rates. The recent discovery of new enzymes and regulators that mediate the hydrolysis of TG has made these measurements more complex. Here, we describe detailed methodology for how to measure lipolysis and specific enzymes’ activities in cells, organs, and their respective extracts. PMID:24529439

  10. Hydrolysis of bovine and caprine milk fat globules by lipoprotein lipase. Effects of heparin and skim milk on lipase distribution and on lipolysis

    SciTech Connect

    Sundheim, G.; Bengtsson-Olivecrona, G.

    1987-12-01

    Heparin can dissociate lipoprotein lipase from casein micelles, and addition of heparin enhances lipolysis in bovine but not in caprine milk. Heparin shortened the lag-time for binding of lipoprotein lipase to milk fat globules and for lipolysis. Heparin counteracted the inhibitory effects of skim milk on binding of lipase and on lipolysis. Heparin stimulated lipolysis in all bovine milk samples when added before cooling and in spontaneously lipolytic milk samples also when added after cooling. Heparin enhanced lipolysis of isolated milk fat globules. Hence, its effect is not solely due to dissociation of lipoprotein lipase from the casein micelles. Cooling of goat milk caused more marked changes in the distribution of lipase than cooling of bovine milk; the fraction of added /sup 125/I-labeled lipase that bound to cream increased from about 8 to 60%. In addition, caprine skim milk caused less inhibition of lipolysis than bovine skim milk. These observations provide an explanation for the high degree of cold storage lipolysis in goat milk. Heparin had only small effects on the distribution of lipoprotein lipase in caprine milk, which explains why heparin has so little effect on lipolysis in caprine milk. The distribution of /sup 35/S-labeled heparin in bovine milk was studied. In warm milk less than 10% bound to the cream fraction, but when milk was cooled, binding of heparin to cream increased to 45%. These results suggest that there exists in the skim fraction a relatively small amount of a heparin-binding protein, which on cooling of milk adsorbs to the milk fat, or suggests that cooling induces a conformational change in a membrane protein such that its affinity for heparin increases.

  11. ATF3 inhibits PPARγ-stimulated transactivation in adipocyte cells

    SciTech Connect

    Jang, Min-Kyung; Jung, Myeong Ho

    2015-01-02

    Highlights: • ATF3 inhibits PPARγ-stimulated transcriptional activation. • ATF3 interacts with PPARγ. • ATF3 suppresses p300-mediated transcriptional coactivation. • ATF3 decreases the binding of PPARγ and recruitment of p300 to PPRE. - Abstract: Previously, we reported that activating transcription factor 3 (ATF3) downregulates peroxisome proliferator activated receptor (PPARγ) gene expression and inhibits adipocyte differentiation in 3T3-L1 cells. Here, we investigated another role of ATF3 on the regulation of PPARγ activity. ATF3 inhibited PPARγ-stimulated transactivation of PPARγ responsive element (PPRE)-containing reporter or GAL4/PPARγ chimeric reporter. Thus, ATF3 effectively repressed rosiglitazone-stimulated expression of adipocyte fatty acid binding protein (aP2), PPARγ target gene, in 3T3-L1 cells. Coimmunoprecipitation and GST pulldown assay demonstrated that ATF3 interacted with PPARγ. Accordingly, ATF3 prevented PPARγ from binding to PPRE on the aP2 promoter. Furthermore, ATF3 suppressed p300-mediated transcriptional coactivation of PPRE-containing reporter. Chromatin immunoprecipitation assay showed that overexpression of ATF3 blocked both binding of PPARγ and recruitment of p300 to PPRE on aP2 promoter induced by rosiglitazone treatment in 3T3-L1 cells. Taken together, these results suggest that ATF3 interacts with PPARγ and represses PPARγ-mediated transactivation through suppression of p300-stimulated coactivation in 3T3-L1 cells, which may play a role in inhibition of adipocyte differentiation.

  12. Characteristics of an Organizational Environment Which Stimulate and Inhibit Creativity.

    ERIC Educational Resources Information Center

    Alencar, Eunice M. L. Soriano de; Bruno-Faria, Maria de Fatima

    1997-01-01

    Analysis of interviews with 25 Brazilian workers concerning characteristics of a work environment that promote or inhibit creativity identified stimulants (such as organization support, support from bosses, and support from colleagues) and obstacles (such as organization structure, boss characteristics, and personal relationships). (DB)

  13. Impaired atrial natriuretic peptide-mediated lipolysis in obesity.

    PubMed

    Rydén, M; Bäckdahl, J; Petrus, P; Thorell, A; Gao, H; Coue, M; Langin, D; Moro, C; Arner, P

    2016-04-01

    Catecholamines and natriuretic peptides (NPs) are the only hormones with pronounced lipolytic effects in human white adipose tissue. Although catecholamine-induced lipolysis is well known to be impaired in obesity and insulin resistance, it is not known whether the effect of NPs is also altered. Catecholamine- and atrial NP (ANP)-induced lipolysis was investigated in abdominal subcutaneous adipocytes in vitro and in situ by microdialysis. In a cohort of 122 women, both catecholamine- and ANP-induced lipolysis in vitro was markedly attenuated in obesity (n=87), but normalized after substantial body weight loss (n=52). The impairment of lipolysis differed between the two hormones when expressing lipolysis per lipid weight, the ratio of stimulated over basal (spontaneous) lipolysis rate or per number of adipocytes. Thus, while the response to catecholamines was lower when expressed as the former two measures, it was higher when expressed per cell number, a consequence of the significantly larger fat cell size in obesity. In contrast, although ANP-induced lipolysis was also attenuated when expressed per lipid weight or the ratio stimulated/basal, it was similar between non-obese and obese subjects when expressed per cell number suggesting that the lipolytic effect of ANP may be even more sensitive to the effects of obesity than catecholamines. Obesity was characterized by a decrease in the protein expression of the signaling NP A receptor (NPRA) and a trend toward increased levels of the clearance receptor NPRC. The impairment in ANP-induced lipolysis observed in vitro was corroborated by microdialysis experiments in situ in a smaller cohort of lean and overweight men. ANP- and catecholamine-induced lipolysis is reversibly attenuated in obesity. The pro-lipolytic effects of ANP are relatively more impaired compared with that of catecholamines, which may in part be due to specific changes in NP receptor expression.

  14. Suppression of adipose lipolysis by long-chain fatty acid analogs.

    PubMed

    Kalderon, Bella; Azazmeh, Narmen; Azulay, Nili; Vissler, Noam; Valitsky, Michael; Bar-Tana, Jacob

    2012-05-01

    Agonist-induced lipolysis of adipose fat is robustly inhibited by insulin or by feedback inhibition by the long-chain fatty acids (LCFA) produced during lipolysis. However, the mode of action of LCFA in suppressing adipose lipolysis is not clear. β,β'-Tetramethyl hexadecanedioic acid (Mββ/ EDICA16) is a synthetic LCFA that is neither esterified into lipids nor β-oxidized, and therefore, it was exploited for suppressing agonist-induced lipolysis in analogy to natural LCFA. Mββ is shown here to suppress isoproterenol-induced lipolysis in the rat in vivo as well as in 3T3-L1 adipocytes. Inhibition of isoproterenol-induced lipolysis is due to decrease in isoproterenol-induced cAMP with concomitant inhibition of the phosphorylation of hormone-sensitive lipase and perilipin by protein kinase A. Suppression of cellular cAMP levels is accounted for by inhibition of the adenylate cyclase due to suppression of Raf1 expression by Mββ-activated AMPK. Suppression of Raf1 is further complemented by induction of components of the unfolded-protein-response by Mββ. Our findings imply genuine inhibition of agonist-induced adipose lipolysis by LCFA, independent of their β-oxidation or reesterification. Mββ suppression of agonist-induced lipolysis and cellular cAMP levels independent of the insulin transduction pathway may indicate that synthetic LCFA could serve as insulin mimetics in the lipolysis context under conditions of insulin resistance.

  15. Inhibition of airway surface fluid absorption by cholinergic stimulation

    PubMed Central

    Joo, Nam Soo; Krouse, Mauri E.; Choi, Jae Young; Cho, Hyung-Ju; Wine, Jeffrey J.

    2016-01-01

    In upper airways airway surface liquid (ASL) depth and clearance rates are both increased by fluid secretion. Secretion is opposed by fluid absorption, mainly via the epithelial sodium channel, ENaC. In static systems, increased fluid depth activates ENaC and decreased depth inhibits it, suggesting that secretion indirectly activates ENaC to reduce ASL depth. We propose an alternate mechanism in which cholinergic input, which causes copious airway gland secretion, also inhibits ENaC-mediated absorption. The conjoint action accelerates clearance, and the increased transport of mucus out of the airways restores ASL depth while cleansing the airways. We were intrigued by early reports of cholinergic inhibition of absorption by airways in some species. To reinvestigate this phenomenon, we studied inward short-circuit currents (Isc) in tracheal mucosa from human, sheep, pig, ferret, and rabbit and in two types of cultured cells. Basal Isc was inhibited 20–70% by the ENaC inhibitor, benzamil. Long-lasting inhibition of ENaC-dependent Isc was also produced by basolateral carbachol in all preparations except rabbit and the H441 cell line. Atropine inhibition produced a slow recovery or prevented inhibition if added before carbachol. The mechanism for inhibition was not determined and is most likely multi-factorial. However, its physiological significance is expected to be increased mucus clearance rates in cholinergically stimulated airways. PMID:26846701

  16. Mechanism of Deep Brain Stimulation: Inhibition, Excitation, or Disruption?

    PubMed

    Chiken, Satomi; Nambu, Atsushi

    2016-06-01

    Deep brain stimulation (DBS), applying high-frequency electrical stimulation to deep brain structures, has now provided an effective therapeutic option for treatment of various neurological and psychiatric disorders. DBS targeting the internal segment of the globus pallidus, subthalamic nucleus, and thalamus is used to treat symptoms of movement disorders, such as Parkinson's disease, dystonia, and tremor. However, the mechanism underlying the beneficial effects of DBS remains poorly understood and is still under debate: Does DBS inhibit or excite local neuronal elements? In this short review, we would like to introduce our recent work on the physiological mechanism of DBS and propose an alternative explanation: DBS dissociates input and output signals, resulting in the disruption of abnormal information flow through the stimulation site. © The Author(s) 2015.

  17. Taurine inhibition of metal-stimulated catecholamine oxidation.

    PubMed

    Dawson, R; Baker, D; Eppler, B; Tang, E; Shih, D; Hern, H; Hu, M

    2000-01-01

    Taurine is an abundant amino acid found in mammalian tissues and it has been suggested to have cytoprotective functions. The aim of the present study was to determine if taurine had the potential to reduce oxidative stress associated with metal-stimulated catecholamine oxidation. Taurine and structural analogs of taurine were tested for their ability to inhibit metal-stimulated quinone formation from dopamine or L-dopa. Oxidative damage to proteins and lipids were also assessed in vitro and the effects of taurine were determined. Taurine (20 mM) was found to decrease significantly ferric iron (50-500 microM)- and manganese (10 microM)-stimulated L-dopa or dopamine oxidation. Taurine had no effect on zinc-induced dopamine oxidation and slightly potentiated copper- and NaIO(4)-stimulated quinone formation. Ferric iron-stimulated lipid peroxidation was not affected by taurine (1-20 mM). Protein carbonyl formation induced by ferric iron (500 microM) and L-dopa (500 microM) was significantly reduced by 10 mM taurine. The cytotoxicity of L-dopa (250 microM) and ferric chloride (75 microM) to LLC-PK(1) cells was attenuated by 10 mM taurine or hypotaurine. Homotaurine alone stimulated L-dopa oxidation and potentiated the cytotoxic effects of ferric iron. Homotaurine was found to be cytotoxic when combined with L-dopa or L-dopa/iron. In contrast, hypotaurine inhibited quinone formation and protected LLC-PK(1) cells. These studies suggest that taurine may exhibit cytoprotective effects against the oxidation products of catecholamines by acting as a scavenger for free radicals and cytotoxic quinones.

  18. In vivo nitric oxide suppression of lipolysis in subcutaneous abdominal adipose tissue is greater in obese than lean women.

    PubMed

    Hickner, Robert C; Kemeny, Gabor; Clark, Paige D; Galvin, Vaughna B; McIver, Kerry L; Evans, Chris A; Carper, Michael J; Garry, Joseph P

    2012-06-01

    Mounting evidence suggests there is a reduced mobilization of stored fat in obese compared to lean women. It has been suggested that this decreased lipid mobilization may lead to, or perpetuate, the obese state; however, there may be a beneficial effect of reduced lipolysis, either by allowing for a sink of excess fatty acids, or by limiting a potentially harmful rise in interstitial and circulating fatty acid concentration. Nitric oxide (NO) may be responsible for a portion of the reduced in vivo rates of lipolysis in obese women because NO reduces adipose tissue lipolysis and adipose tissue nitric oxide synthase (NOS) mRNA is higher in obese than lean individuals. The purpose of this study was to determine if the inhibition of NOS by L-N(g)-monomethyl-L-arginine (L-NMMA) in the absence and presence of lipolytic stimulation would result in a larger increase in lipolytic rate in obese (OB) than lean (LN) women. Microdialysis probes were inserted into the subcutaneous abdominal adipose tissue of seven obese and six lean women to monitor lipolysis. Dialysate glycerol concentration increased in response to L-NMMA in OB (basal 125 ± 26 µmol/l; L-NMMA 225 ± 35 µmol/l) to a greater extent than in LN (basal 70 ± 18 µmol/l; L-NMMA 84 ± 20 µmol/l) women (P < 0.05). Dialysate glycerol increased to a similar extent in OB and LN in response to adrenergic stimulation by isoprenaline or norepinephrine in the presence of L-NMMA. The differential glycerol responses to L-NMMA between obese and lean could not be explained by differential blood flow responses. It can be concluded that NO suppresses basal lipolysis in obese women to a greater extent than in lean women.

  19. Contribution of Adipose Triglyceride Lipase and Hormone-sensitive Lipase to Lipolysis in hMADS Adipocytes*

    PubMed Central

    Bezaire, Véronic; Mairal, Aline; Ribet, Carole; Lefort, Corinne; Girousse, Amandine; Jocken, Johan; Laurencikiene, Jurga; Anesia, Rodica; Rodriguez, Anne-Marie; Ryden, Mikael; Stenson, Britta M.; Dani, Christian; Ailhaud, Gérard; Arner, Peter; Langin, Dominique

    2009-01-01

    Lipolysis is the catabolic pathway by which triglycerides are hydrolyzed into fatty acids. Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) have the capacity to hydrolyze in vitro the first ester bond of triglycerides, but their respective contributions to whole cell lipolysis in human adipocytes is unclear. Here, we have investigated the roles of HSL, ATGL, and its coactivator CGI-58 in basal and forskolin-stimulated lipolysis in a human white adipocyte model, the hMADS cells. The hMADS adipocytes express the various components of fatty acid metabolism and show lipolytic capacity similar to primary cultured adipocytes. We show that lipolysis and fatty acid esterification are tightly coupled except in conditions of stimulated lipolysis. Immunocytochemistry experiments revealed that acute forskolin treatment promotes HSL translocation from the cytosol to small lipid droplets and redistribution of ATGL from the cytosol and large lipid droplets to small lipid droplets, resulting in enriched colocalization of the two lipases. HSL or ATGL overexpression resulted in increased triglyceride-specific hydrolase capacity, but only ATGL overexpression increased whole cell lipolysis. HSL silencing had no effect on basal lipolysis and only partially reduced forskolin-stimulated lipolysis. Conversely, silencing of ATGL or CGI-58 significantly reduced basal lipolysis and essentially abolished forskolin-stimulated lipolysis. Altogether, these results suggest that ATGL/CGI-58 acts independently of HSL and precedes its action in the sequential hydrolysis of triglycerides in human hMADS adipocytes. PMID:19433586

  20. Metabolic response in liver and Brockmann bodies of rainbow trout to inhibition of lipolysis; possible involvement of the hypothalamus-pituitary-interrenal (HPI) axis.

    PubMed

    Librán-Pérez, Marta; Velasco, Cristina; Otero-Rodiño, Cristina; López-Patiño, Marcos A; Míguez, Jesús M; Soengas, José L

    2015-05-01

    We previously demonstrated in rainbow trout that the decrease in circulating levels of fatty acid (FA) induced by treating fish with SDZ WAG 994 (SDZ) induced a counter-regulatory response in which the activation of the hypothalamus-pituitary-interrenal (HPI, equivalent to mammalian hypothalamus-pituitary-adrenal) axis was likely involved. This activation, probably not related to the control of food intake through FA sensor systems but to the modulation of lipolysis in peripheral tissues, liver and Brockmann bodies (BB, the main site of pancreatic endocrine cells in fish), would target the restoration of FA levels in plasma. To assess this hypothesis, we lowered circulating FA levels by treating fish with SDZ alone, or SDZ in the presence of metyrapone (an inhibitor of cortisol synthesis). In liver, the changes observed were not compatible with a direct FA-sensing response but with a stress response, which allows us to suggest that the detection of a FA decrease in the hypothalamus elicits a counter-regulatory response in liver, resulting in an activation of lipolysis to restore FA levels in plasma. The activation of these metabolic changes in liver could be attributable to the activation of the HPI axis and/or to the action of sympathetic pathways. In contrast, in BB, changes in circulating FA levels induce changes in several parameters compatible with the function of FA-sensing systems informing about the decrease in circulating FA levels.

  1. Mechanism of enhanced lipolysis in adipose tissue of exercise-trained rats.

    PubMed

    Bukowiecki, L; Lupien, J; Follea, N; Paradis, A; Richard, D; LeBlanc, J

    1980-12-01

    The effects of exercise training and food restriction on the regulation of lipolysis were studied comparatively in adipocytes isolated from male and female rats. Exercise training inhibited cell proliferation in parametrial, but not in epididymal adipose tissue, whereas it significantly reduced adipocyte size in both fat depots. Adipocyte capacity for responding lipolytically to epinephrine (10 microns) or to ACTH (1 micron) was markedly increased by exercise training. Enhanced lipolysis was also observed when cells isolated from exercise-trained animals were stimulated by bypassing with dibutyryl cyclic AMP (5 mM) or theophylline (5 mM) the early metabolic steps associated with hormonal activation of the adenylate cyclase complex. Significantly, binding of (-)-[3H]dihydroalprenolol to cellular receptor sites was not affected by exercise training. It is therefore concluded that exercise training increases adipocyte responsiveness to lipolytic hormones at a metabolic step distal to stimulus recognition by adrenoreceptors, possibly at the level of protein kinases or lipases. Food restriction markedly reduced adipocyte size and partially mimicked the effects of exercise training on adipocyte proliferation and lipolysis.

  2. Triphenyl phosphate enhances adipogenic differentiation, glucose uptake and lipolysis via endocrine and noradrenergic mechanisms.

    PubMed

    Cano-Sancho, German; Smith, Anna; La Merrill, Michele A

    2017-04-01

    The use of triphenyl phosphate (TPhP) as a flame retardant or plasticizer has increased during the last decade, resulting in widespread human exposure without commensurate toxicity assessment. The main objectives of this study were to assess the in vitro effect of TPhP and its metabolite diphenyl phosphate (DPhP) on the adipogenic differentiation of 3T3-L1 cells, as well as glucose uptake and lipolysis in differentiated 3T3-L1 adipocytes. TPhP increased pre-adipocyte proliferation and subsequent adipogenic differentiation of 3T3-L1 cells, coinciding with increased transcription in the CEBP and PPARG pathway. Treatment of mature adipocytes with TPhP increased the basal- and insulin stimulated- uptake of the glucose analog 2-[N (-7-nitrobenz-2-oxa1, 3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG). This effect was ablated by inhibition of PI3K, a member of the insulin signaling pathway. DPhP had no significant effect on cell proliferation and, compared to TPhP, a weaker effect on adipogenic differentiation and on 2-NBDG uptake. Both TPhP and DPhT significantly enhanced the isoproterenol-induced lipolysis, most likely by increasing the expression of lipolytic genes during and after differentiation. This study suggests that TPhP increases adipogenic differentiation, glucose uptake, and lipolysis in 3T3-L1 cells through endocrine and noradrenergic mechanisms.

  3. Perilipin Promotes HSL-Mediated Adipocyte Lipolysis via Phosphorylation-dependent and Independent Mechanisms

    USDA-ARS?s Scientific Manuscript database

    Hormone-sensitive lipase (HSL) is the predominant lipase effector of catecholamine-stimulated lipolysis in adipocytes. HSL-dependent lipolysis, in response to catecholamines, is mediated by protein kinase A (PKA)-dependent phosphorylation of perilipin A (Peri A), an essential lipid droplet (LD)-ass...

  4. Enhancing and inhibiting stimulated Brillouin scattering in photonic integrated circuits

    PubMed Central

    Merklein, Moritz; Kabakova, Irina V.; Büttner, Thomas F. S.; Choi, Duk-Yong; Luther-Davies, Barry; Madden, Stephen J.; Eggleton, Benjamin J.

    2015-01-01

    On-chip nonlinear optics is a thriving research field, which creates transformative opportunities for manipulating classical or quantum signals in small-footprint integrated devices. Since the length scales are short, nonlinear interactions need to be enhanced by exploiting materials with large nonlinearity in combination with high-Q resonators or slow-light structures. This, however, often results in simultaneous enhancement of competing nonlinear processes, which limit the efficiency and can cause signal distortion. Here, we exploit the frequency dependence of the optical density-of-states near the edge of a photonic bandgap to selectively enhance or inhibit nonlinear interactions on a chip. We demonstrate this concept for one of the strongest nonlinear effects, stimulated Brillouin scattering using a narrow-band one-dimensional photonic bandgap structure: a Bragg grating. The stimulated Brillouin scattering enhancement enables the generation of a 15-line Brillouin frequency comb. In the inhibition case, we achieve stimulated Brillouin scattering free operation at a power level twice the threshold. PMID:25736909

  5. Modulation of adipose tissue lipolysis and body weight by high-density lipoproteins in mice

    PubMed Central

    Wei, H; Averill, M M; McMillen, T S; Dastvan, F; Mitra, P; Subramanian, S; Tang, C; Chait, A; LeBoeuf, R C

    2014-01-01

    Background: Obesity is associated with reduced levels of circulating high-density lipoproteins (HDLs) and its major protein, apolipoprotein (apo) A-I. As a result of the role of HDL and apoA-I in cellular lipid transport, low HDL and apoA-I may contribute directly to establishing or maintaining the obese condition. Methods: To test this, male C57BL/6 wild-type (WT), apoA-I deficient (apoA-I−/−) and apoA-I transgenic (apoA-Itg/tg) mice were fed obesogenic diets (ODs) and monitored for several clinical parameters. We also performed cell culture studies. Results: ApoA-I−/− mice gained significantly more body weight and body fat than WT mice over 20 weeks despite their reduced food intake. During a caloric restriction regime imposed on OD-fed mice, apoA-I deficiency significantly inhibited the loss of body fat as compared with WT mice. Reduced body fat loss with caloric restriction in apoA-I−/− mice was associated with blunted stimulated adipose tissue lipolysis as verified by decreased levels of phosphorylated hormone-sensitive lipase (p-HSL) and lipolytic enzyme mRNA. In contrast to apoA-I−/− mice, apoA-Itg/tg mice gained relatively less weight than WT mice, consistent with other reports. ApoA-Itg/tg mice showed increased adipose tissue lipolysis, verified by increased levels of p-HSL and lipolytic enzyme mRNA. In cell culture studies, HDL and apoA-I specifically increased catecholamine-induced lipolysis possibly through modulating the adipocyte plasma membrane cholesterol content. Conclusions: Thus, apoA-I and HDL contribute to modulating body fat content by controlling the extent of lipolysis. ApoA-I and HDL are key components of lipid metabolism in adipose tissue and constitute new therapeutic targets in obesity. PMID:24567123

  6. Effect of carbohydrate- and protein-rich meals on exercise-induced activation of lipolysis in obese subjects.

    PubMed

    Erdmann, J; Tholl, S; Schusdziarra, V

    2010-04-01

    Exercise is an important part of obesity treatment concepts to support fat mobilisation from adipose tissue and also fat oxidation nolich is impaired in obese subjects. In normal weight subjects it is well known that stimulation of plasma insulin levels by a carbohydrate meal can inhibit lipolysis and subsequent fat oxidation. Since obese subjects frequently have elevated basal and postprandial insulin levels the effect of carbohydrate- and protein-rich test meals on exercise-induced activation of lipolysis is of special interest. Twenty obese subjects performed bicycle exercise for 30 min in the fasted state, 30 min after a carbohydrate-or a protein-rich meal, and 120 min after the carbohydrate meal (n=12), respectively, at low intensity. Activation of lipolysis was assessed by plasma glycerol levels. In addition, plasma insulin, glucose, and lactate concentrations were determined. In comparison to the fasted state, the carbohydrate meal suppressed activation of lipolysis. Following the protein meal, exercise led to an attenuated but significant increase of glycerol levels. A similar rise was observed when the carbohydrate meal was ingested 2 h prior to the exercise bout. To improve exercise-induced lipolysis and subsequent fat oxidation during low-intensity exercise obese subjects should not ingest carbohydrates immediately before exercise. Hunger sensations should be satisfied with protein-rich food. When carbohydrates are consumed 2 h prior to exercise its lipolytic effect is comparable to the protein meal. These data are useful in every day dietary counselling and might help to improve weight loss during obesity treatment. Georg Thieme Verlag KG Stuttgart New York.

  7. Cadmium inhibits acid secretion in stimulated frog gastric mucosa

    SciTech Connect

    Gerbino, Andrea; Debellis, Lucantonio; Caroppo, Rosa; Curci, Silvana; Colella, Matilde

    2010-06-01

    Cadmium, a toxic environmental pollutant, affects the function of different organs such as lungs, liver and kidney. Less is known about its toxic effects on the gastric mucosa. The aim of this study was to investigate the mechanisms by which cadmium impacts on the physiology of gastric mucosa. To this end, intact amphibian mucosae were mounted in Ussing chambers and the rate of acid secretion, short circuit current (I{sub sc}), transepithelial potential (V{sub t}) and resistance (R{sub t}) were recorded in the continuous presence of cadmium. Addition of cadmium (20 {mu}M to 1 mM) on the serosal but not luminal side of the mucosae resulted in inhibition of acid secretion and increase in NPPB-sensitive, chloride-dependent short circuit current. Remarkably, cadmium exerted its effects only on histamine-stimulated tissues. Experiments with TPEN, a cell-permeant chelator for heavy metals, showed that cadmium acts from the intracellular side of the acid secreting cells. Furthermore, cadmium-induced inhibition of acid secretion and increase in I{sub sc} cannot be explained by an action on: 1) H{sub 2} histamine receptor, 2) Ca{sup 2+} signalling 3) adenylyl cyclase or 4) carbonic anhydrase. Conversely, cadmium was ineffective in the presence of the H{sup +}/K{sup +}-ATPase blocker omeprazole suggesting that the two compounds likely act on the same target. Our findings suggest that cadmium affects the functionality of histamine-stimulated gastric mucosa by inhibiting the H{sup +}/K{sup +}-ATPase from the intracellular side. These data shed new light on the toxic effect of this dangerous environmental pollutant and may result in new avenues for therapeutic intervention in acute and chronic intoxication.

  8. Alpinia officinarum Stimulates Osteoblast Mineralization and Inhibits Osteoclast Differentiation.

    PubMed

    Shim, Ki-Shuk; Lee, Chung-Jo; Yim, Nam-Hui; Gu, Min Jung; Ma, Jin Yeul

    2016-01-01

    Alpinia officinarum rhizome has been used as a traditional herbal remedy to treat inflammatory and internal diseases. Based on the previously observed inhibitory effect of A. officinarum rhizome in an arthritis model, we evaluated whether a water extract of A. officinarum rhizome (WEAO) would enhance in vitro osteoblast mineralization using calvarial osteoblast precursor cells or would inhibit in vitro osteoclast differentiation and bone resorption using bone marrow derived macrophages. In osteoblasts, WEAO enhanced the mRNA levels of transcription factor (runt-related transcription factor 2, smad1, smad5, and junB) and marker (bone morphogenetic protein-2, collagen type 1alpha1, and osteocalcin) genes related to osteoblast mineralization, consistent with increased alizarin red S staining intensity. WEAO markedly inhibited osteoclast differentiation by suppressing the receptor activator for nuclear factor-[Formula: see text]B ligand-induced downregulation of inhibitor of DNA binding 2 and V-maf musculoaponeurotic fibrosarcoma oncogene homolog B and the phosphorylation of c-Jun N-terminal kinase, p38, nuclear factor-[Formula: see text]B, c-Src, and Bruton's tyrosine kinase to induce nuclear factor of activated T cells cytoplasmic 1 expression. WEAO also suppressed the resorbing activity of mature osteoclasts by altering actin ring formation. Therefore, the results of this study demonstrate that WEAO stimulates osteoblast mineralization and inhibits osteoclast differentiation. Thus, WEAO may be a promising herbal candidate to treat or prevent pathological bone diseases by regulating the balance between osteoclast and osteoblast activity.

  9. Effects of Glucagon on Lipolysis and Ketogenesis in Normal and Diabetic Men

    PubMed Central

    Liljenquist, John E.; Bomboy, James D.; Lewis, Stephen B.; Sinclair-Smith, Bruce C.; Felts, Philip W.; Lacy, William W.; Crofford, Oscar B.; Liddle, Grant W.

    1974-01-01

    The effect of glucagon (50 ng/kg/min) on arterial glycerol concentration and net splanchnic production of total ketones and glucose was studied after an overnight fast in four normal and five insulin-dependent diabetic men. Brachial artery and hepatic vein catheters were inserted and splanchnic blood flow determined using indocyanine green. The glucagon infusion resulted in a mean circulating plasma level of 4,420 pg/ml. In the normal subjects, the glucagon infusion resulted in stimulation of insulin secretion indicated by rising levels of immunoreactive insulin and C-peptide immunoreactivity. Arterial glycerol concentration (an index of lipolysis) declined markedly and net splanchnic total ketone production was virtually abolished. In contrast, the diabetic subjects secreted no insulin (no rise in C-peptide immunoreactivity) in response to glucagon. Arterial glycerol and net splanchnic total ketone production in these subjects rose significantly (P=<0.05) when compared with the results in four diabetics who received a saline infusion after undergoing the same catheterization procedure. Net splanchnic glucose production rose markedly during glucagon stimulation in the normals and diabetics despite the marked rise in insulin in the normals. Thus, the same level of circulating insulin which markedly suppressed lipolysis and ketogenesis in the normals failed to inhibit the glucagon-mediated increase in net splanchnic glucose production. It is concluded (a) that glucagon at high concentration is capable of stimulating lipolysis and ketogenesis in insulin-deficient diabetic man; (b) that insulin, mole for mole, has more antilipolytic activity in man than glucagon has lipolytic activity; and (c) that glucagon, on a molar basis, has greater stimulatory activity than insulin has inhibitory activity on hepatic glucose release. PMID:4808635

  10. G0/G1 Switch Gene 2 Regulates Cardiac Lipolysis*

    PubMed Central

    Heier, Christoph; Radner, Franz P. W.; Moustafa, Tarek; Schreiber, Renate; Grond, Susanne; Eichmann, Thomas O.; Schweiger, Martina; Schmidt, Albrecht; Cerk, Ines K.; Oberer, Monika; Theussl, H.-Christian; Wojciechowski, Jacek; Penninger, Josef M.; Zimmermann, Robert; Zechner, Rudolf

    2015-01-01

    The anabolism and catabolism of myocardial triacylglycerol (TAG) stores are important processes for normal cardiac function. TAG synthesis detoxifies and stockpiles fatty acids to prevent lipotoxicity, whereas TAG hydrolysis (lipolysis) remobilizes fatty acids from endogenous storage pools as energy substrates, signaling molecules, or precursors for complex lipids. This study focused on the role of G0/G1 switch 2 (G0S2) protein, which was previously shown to inhibit the principal TAG hydrolase adipose triglyceride lipase (ATGL), in the regulation of cardiac lipolysis. Using wild-type and mutant mice, we show the following: (i) G0S2 is expressed in the heart and regulated by the nutritional status with highest expression levels after re-feeding. (ii) Cardiac-specific overexpression of G0S2 inhibits cardiac lipolysis by direct protein-protein interaction with ATGL. This leads to severe cardiac steatosis. The steatotic hearts caused by G0S2 overexpression are less prone to fibrotic remodeling or cardiac dysfunction than hearts with a lipolytic defect due to ATGL deficiency. (iii) Conversely to the phenotype of transgenic mice, G0S2 deficiency results in a de-repression of cardiac lipolysis and decreased cardiac TAG content. We conclude that G0S2 acts as a potent ATGL inhibitor in the heart modulating cardiac substrate utilization by regulating cardiac lipolysis. PMID:26350455

  11. Magnetic field inhibits isolated lymphocytes' proliferative response to mitogen stimulation.

    PubMed

    Roman, Adam; Zyss, Tomasz; Nalepa, Irena

    2005-04-01

    We aimed to find out how the exposure of isolated lymphocytes to a pulsed magnetic field (MF) affected their in vitro proliferative response to mitogenic stimulation. Cells were exposed to MF of various intensities (0.3, 0.6, and 1.2 T) at a constant frequency of 30 Hz, for a period of 60, 180, and 330 s. Then, the proliferative response of splenocytes was induced by optimal concentrations of concanavalin A (Con A; mitogenic toward T cells), bacterial lipopolysaccharide (LPS; mitogenic toward B cells), or pokeweed mitogen (PWM; mitogenic toward both populations). We found that the exposure of lymphocytes to the MF profoundly inhibited their proliferative response to mitogens. The suppressive action of the MF on B and T cell proliferation was intensified when a cooperative response of those two lymphocyte populations was simultaneously induced by PWM. The inhibitory effect of MF depended on the exposure time and MF intensity. Prolonged exposure and/or a stronger intensity of the MF weakened its inhibitory influence on the response of lymphocyte to mitogenic stimulation. The data show that an exposure to MF may influence the activity of lymphocytes in their response to mitogenic stimuli.

  12. Role of alpha 1- and alpha 2-adrenoceptors in catecholamine-induced hyperglycaemia, lipolysis and insulin secretion in conscious fasted rabbits.

    PubMed

    Moratinos, J; Carpene, C; de Pablos, I; Reverte, M

    1988-06-01

    1. In conscious fasted rabbits an intravenous infusion of clonidine (2 micrograms kg-1 min-1) induced hyperglycaemia. The increase in blood glucose was accompanied by an inhibition of insulin secretion and basal lipolysis. 2. Yohimbine infused at a rate of 20 micrograms kg-1 min-1 suppressed clonidine-induced hyperglycaemia and blocked the inhibitory effect on insulin secretion mediated by the alpha 2-adrenoceptor agonist. 3. The intravenous infusion of amidephrine (10 micrograms kg-1 min-1) induced an increase in insulin secretion in the absence of patent hyperglycaemia. Prazosin, 0.3 mg kg-1 s.c. selectively antagonized the effect of amidephrine on insulin secretion. 4. Isoprenaline infusion (4.4 micrograms kg-1 min-1) evoked a significant increase in blood glycerol and immunoreactive insulin plasma levels. Both responses were clearly attenuated when alpha 2-adrenoceptors were simultaneously stimulated by selective (clonidine) and less selective (phenylephrine, 20 micrograms kg-1 min-1) agonists. 5. Amidephrine infusion did not induce appreciable changes in blood glycerol nor did it modify, isoprenaline-induced lipolytic response. 6. Simultaneous infusion of isoprenaline and amidephrine induced a remarkable increase in insulin secretion. 7. It is concluded that in normal fasted rabbits stimulation of alpha 2-adrenoceptors depresses basal and beta-adrenoceptor mediated lipolysis and insulin secretion. On the other hand, selective stimulation of alpha 1-adrenoceptors does not affect lipolysis but induces insulin release. Simultaneous stimulation of alpha 1- and beta-adrenoceptors potentiates the insulin secretory response.

  13. Liver X receptor (LXR) regulates human adipocyte lipolysis.

    PubMed

    Stenson, Britta M; Rydén, Mikael; Venteclef, Nicolas; Dahlman, Ingrid; Pettersson, Annie M L; Mairal, Aline; Aström, Gaby; Blomqvist, Lennart; Wang, Victoria; Jocken, Johan W E; Clément, Karine; Langin, Dominique; Arner, Peter; Laurencikiene, Jurga

    2011-01-07

    The Liver X receptor (LXR) is an important regulator of carbohydrate and lipid metabolism in humans and mice. We have recently shown that activation of LXR regulates cellular fuel utilization in adipocytes. In contrast, the role of LXR in human adipocyte lipolysis, the major function of human white fat cells, is not clear. In the present study, we stimulated in vitro differentiated human and murine adipocytes with the LXR agonist GW3965 and observed an increase in basal lipolysis. Microarray analysis of human adipocyte mRNA following LXR activation revealed an altered gene expression of several lipolysis-regulating proteins, which was also confirmed by quantitative real-time PCR. We show that expression and intracellular localization of perilipin1 (PLIN1) and hormone-sensitive lipase (HSL) are affected by GW3965. Although LXR activation does not influence phosphorylation status of HSL, HSL activity is required for the lipolytic effect of GW3965. This effect is abolished by PLIN1 knockdown. In addition, we demonstrate that upon activation, LXR binds to the proximal regions of the PLIN1 and HSL promoters. By selective knock-down of either LXR isoform, we show that LXRα is the major isoform mediating the lipolysis-related effects of LXR. In conclusion, the present study demonstrates that activation of LXRα up-regulates basal human adipocyte lipolysis. This is at least partially mediated through LXR binding to the PLIN1 promoter and down-regulation of PLIN1 expression.

  14. Liver X Receptor (LXR) Regulates Human Adipocyte Lipolysis*

    PubMed Central

    Stenson, Britta M.; Rydén, Mikael; Venteclef, Nicolas; Dahlman, Ingrid; Pettersson, Annie M. L.; Mairal, Aline; Åström, Gaby; Blomqvist, Lennart; Wang, Victoria; Jocken, Johan W. E.; Clément, Karine; Langin, Dominique; Arner, Peter; Laurencikiene, Jurga

    2011-01-01

    The Liver X receptor (LXR) is an important regulator of carbohydrate and lipid metabolism in humans and mice. We have recently shown that activation of LXR regulates cellular fuel utilization in adipocytes. In contrast, the role of LXR in human adipocyte lipolysis, the major function of human white fat cells, is not clear. In the present study, we stimulated in vitro differentiated human and murine adipocytes with the LXR agonist GW3965 and observed an increase in basal lipolysis. Microarray analysis of human adipocyte mRNA following LXR activation revealed an altered gene expression of several lipolysis-regulating proteins, which was also confirmed by quantitative real-time PCR. We show that expression and intracellular localization of perilipin1 (PLIN1) and hormone-sensitive lipase (HSL) are affected by GW3965. Although LXR activation does not influence phosphorylation status of HSL, HSL activity is required for the lipolytic effect of GW3965. This effect is abolished by PLIN1 knockdown. In addition, we demonstrate that upon activation, LXR binds to the proximal regions of the PLIN1 and HSL promoters. By selective knock-down of either LXR isoform, we show that LXRα is the major isoform mediating the lipolysis-related effects of LXR. In conclusion, the present study demonstrates that activation of LXRα up-regulates basal human adipocyte lipolysis. This is at least partially mediated through LXR binding to the PLIN1 promoter and down-regulation of PLIN1 expression. PMID:21030586

  15. Lipolysis Response to Endoplasmic Reticulum Stress in Adipose Cells*

    PubMed Central

    Deng, Jingna; Liu, Shangxin; Zou, Liangqiang; Xu, Chong; Geng, Bin; Xu, Guoheng

    2012-01-01

    In obesity and diabetes, adipocytes show significant endoplasmic reticulum (ER) stress, which triggers a series of responses. This study aimed to investigate the lipolysis response to ER stress in rat adipocytes. Thapsigargin, tunicamycin, and brefeldin A, which induce ER stress through different pathways, efficiently activated a time-dependent lipolytic reaction. The lipolytic effect of ER stress occurred with elevated cAMP production and protein kinase A (PKA) activity. Inhibition of PKA reduced PKA phosphosubstrates and attenuated the lipolysis. Although both ERK1/2 and JNK are activated during ER stress, lipolysis is partially suppressed by inhibiting ERK1/2 but not JNK and p38 MAPK and PKC. Thus, ER stress induces lipolysis by activating cAMP/PKA and ERK1/2. In the downstream lipolytic cascade, phosphorylation of lipid droplet-associated protein perilipin was significantly promoted during ER stress but attenuated on PKA inhibition. Furthermore, ER stress stimuli did not alter the levels of hormone-sensitive lipase and adipose triglyceride lipase but caused Ser-563 and Ser-660 phosphorylation of hormone-sensitive lipase and moderately elevated its translocation from the cytosol to lipid droplets. Accompanying these changes, total activity of cellular lipases was promoted to confer the lipolysis. These findings suggest a novel pathway of the lipolysis response to ER stress in adipocytes. This lipolytic activation may be an adaptive response that regulates energy homeostasis but with sustained ER stress challenge could contribute to lipotoxicity, dyslipidemia, and insulin resistance because of persistently accelerated free fatty acid efflux from adipocytes to the bloodstream and other tissues. PMID:22223650

  16. Resveratrol regulates lipolysis via adipose triglyceride lipase.

    PubMed

    Lasa, Arrate; Schweiger, Martina; Kotzbeck, Petra; Churruca, Itziar; Simón, Edurne; Zechner, Rudolf; Portillo, María del Puy

    2012-04-01

    Resveratrol has been reported to increase adrenaline-induced lipolysis in 3T3-L1 adipocytes. The general aim of the present work was to gain more insight concerning the effects of trans-resveratrol on lipid mobilization. The specific purpose was to assess the involvement of the two main lipases: adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), in the activation of lipolysis induced by this molecule. For lipolysis experiments, 3T3-L1 and human SGBS adipocytes as well as adipose tissue from wild-type, ATGL knockout and HSL knockout mice were used. Moreover, gene and protein expressions of these lipases were analyzed. Resveratrol-induced free fatty acids release but not glycerol release in 3T3-L1 under basal and isoproterenol-stimulating conditions and under isoproterenol-stimulating conditions in SGBS adipocytes. When HSL was blocked by compound 76-0079, free fatty acid release was still induced by resveratrol. By contrast, in the presence of the compound C, an inhibitor of adenosine monophosphate-activated protein kinase, resveratrol effect was totally blunted. Resveratrol increased ATGL gene and protein expressions, an effect that was not observed for HSL. Resveratrol increased fatty acids release in epididymal adipose tissue from wild-type and HSL knockout mice but not in that adipose tissue from ATGL knockout mice. Taking as a whole, the present results provide novel evidence that resveratrol regulates lipolytic activity in human and murine adipocytes, as well as in white adipose tissue from mice, acting mainly on ATGL at transcriptional and posttranscriptional levels. Enzyme activation seems to be induced via adenosine monophosphate-activated protein kinase. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Fibroblast growth factor 21 regulates lipolysis in white adipose tissue but is not required for ketogenesis and triglyceride clearance in liver.

    PubMed

    Hotta, Yuhei; Nakamura, Hirotoshi; Konishi, Morichika; Murata, Yusuke; Takagi, Hiroyuki; Matsumura, Shigenobu; Inoue, Kazuo; Fushiki, Tohru; Itoh, Nobuyuki

    2009-10-01

    Fibroblast growth factors (Fgfs) are polypeptide growth factors with diverse functions. Fgf21, a unique member of the Fgf family, is expected to function as a metabolic regulator in an endocrine manner. Hepatic Fgf21 expression was increased by fasting. The phenotypes of hepatic Fgf21 transgenic or knockdown mice and high-fat, low-carbohydrate ketogenic diet-fed mice suggests that Fgf21 stimulates lipolysis in the white adipose tissue during normal feeding and is required for ketogenesis and triglyceride clearance in the liver during fasting. However, the physiological roles of Fgf21 remain unclear. To elucidate the physiological roles of Fgf21, we generated Fgf21 knockout (KO) mice by targeted disruption. Fgf21 KO mice were viable, fertile, and seemingly normal. Food intake, oxygen consumption, and energy expenditure were also essentially unchanged in Fgf21 KO mice. However, hypertrophy of adipocytes, decreased lipolysis in adipocytes, and decreased blood nonesterified fatty acid levels were observed when Fgf21 KO mice were fed normally. In contrast, increased lipolysis in adipocytes and increased blood nonesterified fatty acid levels were observed in Fgf21 KO mice by fasting for 24 h, indicating that Fgf21 stimulates lipolysis in the white adipose tissue during feeding but inhibits it during fasting. In contrast, unexpectedly, hepatic triglyceride levels were essentially unchanged in Fgf21 KO mice. In addition, ketogenesis in Fgf21 KO mice was not impaired by fasting for 24 h. The present results indicate that Fgf21 regulates lipolysis in adipocytes in response to the metabolic state but is not required for ketogenesis and triglyceride clearance in the liver.

  18. Prolonged treatment with prostaglandin E1 increases the rate of lipolysis in rat adipocytes.

    PubMed

    Freeth, Amy; Udupi, Vidya; Basile, Robin; Green, Allan

    2003-06-13

    Prolonged treatment of adipocytes with certain inhibitors of lipolysis, including N(6)-phenylisopropyl adenosine (PIA) and prostaglandin E(1) (PGE(1)) leads to down-regulation of G(i). Prolonged treatment with PIA increases the rate of lipolysis, and we have reported that tumor necrosis factor-alpha (TNF alpha) stimulates lipolysis by down-regulating G(i). To determine the relationship between G(i) concentration and lipolysis, we have investigated the effect of two other acute inhibitors of lipolysis; PGE(1), which down-regulates G(i), and nicotinic acid (NA), which does not down-regulate G(i). Rat adipocytes were incubated with PIA (300 nM), PGE(1) (3 microM) or nicotinic acid (1 mM) for 24 h. The rate of lipolysis (glycerol release) was increased approximately 2 to 3-fold in PIA-treated cells, and in PGE(1)-treated cells. Conversely, the rate of lipolysis was not altered by the prolonged nicotinic acid treatment. These findings support the hypothesis that the rate of lipolysis in adipocytes is determined, at least partly, by the cellular concentration of G(i) proteins.

  19. Inhibition of LRRK2 kinase activity stimulates macroautophagy☆

    PubMed Central

    Manzoni, Claudia; Mamais, Adamantios; Dihanich, Sybille; Abeti, Rosella; Soutar, Marc P.M.; Plun-Favreau, Helene; Giunti, Paola; Tooze, Sharon A.; Bandopadhyay, Rina; Lewis, Patrick A.

    2013-01-01

    Leucine Rich Repeat Kinase 2 (LRRK2) is one of the most important genetic contributors to Parkinson's disease. LRRK2 has been implicated in a number of cellular processes, including macroautophagy. To test whether LRRK2 has a role in regulating autophagy, a specific inhibitor of the kinase activity of LRRK2 was applied to human neuroglioma cells and downstream readouts of autophagy examined. The resulting data demonstrate that inhibition of LRRK2 kinase activity stimulates macroautophagy in the absence of any alteration in the translational targets of mTORC1, suggesting that LRRK2 regulates autophagic vesicle formation independent of canonical mTORC1 signaling. This study represents the first pharmacological dissection of the role LRRK2 plays in the autophagy/lysosomal pathway, emphasizing the importance of this pathway as a marker for LRRK2 physiological function. Moreover it highlights the need to dissect autophagy and lysosomal activities in the context of LRRK2 related pathologies with the final aim of understanding their aetiology and identifying specific targets for disease modifying therapies in patients. PMID:23916833

  20. Brain sites mediating corticosteroid feedback inhibition of stimulated ACTH secretion

    SciTech Connect

    Jacobson, L.

    1989-01-01

    There is substantial evidence that the brain mediates stress-induced and circadian increases in ACTH secretion and that corticosteroid concentrations which normalize basal plasma ACTH are insufficient to normalize ACTH responses to circadian or stressful stimuli in adrenalectomized rats. To identify brain sites mediating corticosteroid inhibition of stimulated ACTH secretion, two approaches were used. The first compared brain ({sup 14}C)-2-deoxyglucose uptake in rats with differential ACTH responses to stress. Relative to sham-adrenalectomized (SHAM) rats, adrenalectomized rats replaced with low, constant corticosterone levels via a subcutaneous corticosterone pellet (B-PELLET) exhibited elevated and prolonged ACTH responses to a variety of stimuli. Adrenalectomized rate given a circadian corticosterone rhythm via corticosterone in their drinking water exhibited elevated ACTH levels immediately after stress, but unlike B-PELLET rats, terminated stress induced ACTH secretion normally relative to SHAMS. Therefore, the abnormal ACTH responses to stress in B-PELLET rats were due to the lack of both circadian variations and stress-induced increases in corticosterone. Hypoxia was selected as a standardized stimulus for correlating brain ({sup 14}C)-2-deoxyglucose uptake with ACTH secretion. In intact rats, increases in plasma ACTH and decreases in arterial PO{sub 2} correlated with the severity of hypoxia at arterial PCO{sub 2} below 60 mm Hg. Hypoxia PELLET vs. SHAM rats. However, in preliminary experiments, although hypoxia increased brain 2-deoxyglucose uptake in most brain regions, plasma ACTH correlated poorly with 2-deoxyglucose uptake at 12% and 10% O{sub 2}.

  1. High molecular weight plant heteropolysaccharides stimulate fibroblasts but inhibit keratinocytes.

    PubMed

    Shahbuddin, Munira; Shahbuddin, Dahlia; Bullock, Anthony J; Ibrahim, Halijah; Rimmer, Stephen; MacNeil, Sheila

    2013-06-28

    Konjac glucomannan (KGM) is a natural polysaccharide of β(1-4)-D-glucomannopyranosyl backbone of D-mannose and D-glucose derived from the tuber of Amorphophallus konjac C. Koch. KGM has been reported to have a wide range of activities including wound healing. In this study we examined KGM extracts prepared from five plant species, (Amorphophallus konjac Koch, Amorphophallus oncophyllus, Amorphophallus prainii, Amorphophallus paeoniifolius and Amorphophallus elegans) for their effects on cultured human keratinocytes and fibroblasts. Extracts from A. konjac Koch, A. oncophyllus and A. prainii (but not from A. paeoniifolius or A. elegans) stimulated fibroblast proliferation both in the absence and presence of serum. However, these materials inhibited keratinocyte proliferation. The fibroblast stimulatory activity was associated with high molecular weight fractions of KGM and was lost following ethanol extraction or enzyme digestion with β-mannanase. It was also reduced by the addition of concanavalin A but not mannose suggesting that these heteropolysaccharides are acting on lectins but not via receptors specific to mannose. The most dramatic effect of KGM was seen in its ability to support fibroblasts for 3weeks under conditions of deliberate media starvation. This effect did not extend to supporting keratinocytes under conditions of media starvation but KGM did significantly help support adipose derived stem cells under media starvation conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. The role of mouse Akt2 in insulin-dependent suppression of adipocyte lipolysis in vivo

    PubMed Central

    Koren, Shlomit; DiPilato, Lisa M.; Emmett, Matthew J.; Shearin, Abigail L.; Chu, Qingwei; Monks, Bob; Birnbaum, Morris J.

    2015-01-01

    Aim/hypothesis The release of fatty acids from adipocytes, i.e. lipolysis, is maintained under tight control, primarily by the opposing actions of catecholamines and insulin. A widely accepted model is that insulin antagonises catecholamine-dependent lipolysis through phosphorylation and activation of cAMP phosphodiesterase 3B (PDE3B) by the serine-threonine protein kinase Akt (protein kinase B). Recently, this hypothesis has been challenged, as in cultured adipocytes insulin appears, under some conditions, to suppress lipolysis independently of Akt. Methods To address the requirement for Akt2, the predominant isoform expressed in classic insulin target tissues, in the suppression of fatty acid release in vivo, we assessed lipolysis in mice lacking Akt2. Results In the fed state and following an oral glucose challenge, Akt2 null mice were glucose intolerant and hyperinsulinaemic, but nonetheless exhibited normal serum NEFA and glycerol levels, suggestive of normal suppression of lipolysis. Furthermore, insulin partially inhibited lipolysis in Akt2 null mice during an insulin tolerance test (ITT) and hyperinsulinaemic–euglycaemic clamp, respectively. In support of these in vivo observations, insulin antagonised catecholamine-induced lipolysis in primary brown fat adipocytes from Akt2-deficient nice. Conclusion These data suggest that suppression of lipolysis by insulin in hyperinsulinaemic states can take place in the absence of Akt2. PMID:25740694

  3. The role of mouse Akt2 in insulin-dependent suppression of adipocyte lipolysis in vivo.

    PubMed

    Koren, Shlomit; DiPilato, Lisa M; Emmett, Matthew J; Shearin, Abigail L; Chu, Qingwei; Monks, Bob; Birnbaum, Morris J

    2015-05-01

    The release of fatty acids from adipocytes, i.e. lipolysis, is maintained under tight control, primarily by the opposing actions of catecholamines and insulin. A widely accepted model is that insulin antagonises catecholamine-dependent lipolysis through phosphorylation and activation of cAMP phosphodiesterase 3B (PDE3B) by the serine-threonine protein kinase Akt (protein kinase B). Recently, this hypothesis has been challenged, as in cultured adipocytes insulin appears, under some conditions, to suppress lipolysis independently of Akt. To address the requirement for Akt2, the predominant isoform expressed in classic insulin target tissues, in the suppression of fatty acid release in vivo, we assessed lipolysis in mice lacking Akt2. In the fed state and following an oral glucose challenge, Akt2 null mice were glucose intolerant and hyperinsulinaemic, but nonetheless exhibited normal serum NEFA and glycerol levels, suggestive of normal suppression of lipolysis. Furthermore, insulin partially inhibited lipolysis in Akt2 null mice during an insulin tolerance test (ITT) and hyperinsulinaemic-euglycaemic clamp, respectively. In support of these in vivo observations, insulin antagonised catecholamine-induced lipolysis in primary brown fat adipocytes from Akt2-deficient mice. These data suggest that suppression of lipolysis by insulin in hyperinsulinaemic states can take place in the absence of Akt2.

  4. Basal lipolysis, not the degree of insulin resistance, differentiates large from small isolated adipocytes in high-fat fed mice.

    PubMed

    Wueest, S; Rapold, R A; Rytka, J M; Schoenle, E J; Konrad, D

    2009-03-01

    Adipocytes in obesity are characterised by increased cell size and insulin resistance compared with adipocytes isolated from lean patients. However, it is not clear at present whether hypertrophy actually does drive adipocyte insulin resistance. Thus, the aim of the present study was to metabolically characterise small and large adipocytes isolated from epididymal fat pads of mice fed a high-fat diet (HFD). C57BL/6J mice were fed normal chow or HFD for 8 weeks. Adipocytes from epididymal fat pads were isolated by collagenase digestion and, in HFD-fed mice, separated into two fractions according to their size by filtration through a nylon mesh. Viability was assessed by lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium assays. Basal and insulin-stimulated D-[U-(14)C]glucose incorporation and lipolysis were measured. Protein levels and mRNA expression were determined by western blot and real-time RT-PCR, respectively. Insulin-stimulated D-[U-(14)C]glucose incorporation into adipocytes isolated from HFD-fed mice was reduced by 50% compared with adipocytes from chow-fed mice. However, it was similar between small (average diameter 60.9 +/- 3.1 microm) and large (average diameter 83.0 +/- 6.6 microm) adipocytes. Similarly, insulin-stimulated phosphorylation of protein kinase B and AS160 were reduced to the same extent in small and large adipocytes isolated from HFD-mice. In addition, insulin failed to inhibit lipolysis in both adipocyte fractions, whereas it decreased lipolysis by 30% in adipocytes of chow-fed mice. In contrast, large and small adipocytes differed in basal lipolysis rate, which was twofold higher in the larger cells. The latter finding was associated with higher mRNA expression levels of Atgl (also known as Pnpla2) and Hsl (also known as Lipe) in larger adipocytes. Viability was not different between small and large adipocytes. Rate of basal lipolysis but not insulin responsiveness is different between small and large

  5. Rare adverse effect of spinal cord stimulation: micturition inhibition.

    PubMed

    La Grua, Marco; Michelagnoli, Giuliano

    2010-06-01

    In current medical literature, most of the reported complications of spinal cord stimulation concern technical problems, such as lead malfunction, migration, breakage, or internal pulse generator dysfunction, whereas reports about the side effects on internal organ function caused by spinal cord stimulation are rare. In this clinical report, we describe uncommon side effects owing to spinal cord stimulation in a patient with chronic neuropathic pain. Our patient developed unexpected urinary retention during electrical epidural stimulation. This case report highlights the incomplete knowledge about the mechanism of action of spinal cord stimulation and its influence on the interactions between the autonomic nervous system and voluntary control of urinary function. The complete recovery of bladder function after the interruption of stimulation suggests that electrical stimulation caused the adverse effects in this clinical case.

  6. Inhibition of apolipoprotein B synthesis stimulates endoplasmic reticulum autophagy that prevents steatosis

    PubMed Central

    Conlon, Donna M.; Thomas, Tiffany; Fedotova, Tatyana; Di Paolo, Gilbert; Chan, Robin B.; Gibeley, Sarah; Liu, Jing; Ginsberg, Henry N.

    2016-01-01

    Inhibition of VLDL secretion reduces plasma levels of atherogenic apolipoprotein B (apoB) lipoproteins but can also cause hepatic steatosis. Approaches targeting apoB synthesis, which lies upstream of VLDL secretion, have potential to effectively reduce dyslipidemia but can also lead to hepatic accumulation of unsecreted triglycerides (TG). Here, we found that treating mice with apoB antisense oligonucleotides (ASOs) for 6 weeks decreased VLDL secretion and plasma cholesterol without causing steatosis. The absence of steatosis was linked to an increase in ER stress in the first 3 weeks of ASO treatment, followed by development of ER autophagy at the end of 6 weeks of treatment. The latter resulted in increased fatty acid (FA) oxidation that was inhibited by both chloroquine and 3-methyl adenine, consistent with trafficking of ER TG through the autophagic pathway before oxidation. These findings support the concept that inhibition of apoB synthesis traps lipids that have been transferred to the ER by microsomal TG transfer protein (MTP), inducing ER stress. ER stress then triggers ER autophagy and subsequent lysosomal lipolysis of TG, followed by mitochondrial oxidation of released FA, leading to prevention of steatosis. The identification of this pathway indicates that inhibition of VLDL secretion remains a viable target for therapies aiming to reduce circulating levels of atherogenic apoB lipoproteins. PMID:27599291

  7. Reflex inhibition of cutaneous and muscle vasoconstrictor neurons during stimulation of cutaneous and muscle nociceptors.

    PubMed

    Kirillova-Woytke, Irina; Baron, Ralf; Jänig, Wilfrid

    2014-05-01

    Cutaneous (CVC) and muscle (MVC) vasoconstrictor neurons exhibit typical reflex patterns to physiological stimulation of somatic and visceral afferent neurons. Here we tested the hypothesis that CVC neurons are inhibited by stimulation of cutaneous nociceptors but not of muscle nociceptors and that MVC neurons are inhibited by stimulation of muscle nociceptors but not of cutaneous nociceptors. Activity in the vasoconstrictor neurons was recorded from postganglionic axons isolated from the sural nerve or the lateral gastrocnemius-soleus nerve in anesthetized rats. The nociceptive afferents were excited by mechanical stimulation of the toes of the ipsilateral hindpaw (skin), by hypertonic saline injected into the ipsi- or contralateral gastrocnemius-soleus muscle, or by heat or noxious cold stimuli applied to the axons in the common peroneal nerve or tibial nerve. The results show that CVC neurons are inhibited by noxious stimulation of skin but not by noxious stimulation of skeletal muscle and that MVC neurons are inhibited by noxious stimulation of skeletal muscle but not by noxious stimulation of skin. These inhibitory reflexes are mostly lateralized and are most likely organized in the spinal cord. Stimulation of nociceptive cold-sensitive afferents does not elicit inhibitory or excitatory reflexes in CVC or MVC neurons. The reflex inhibition of activity in CVC or MVC neurons generated by stimulation of nociceptive cutaneous or muscle afferents during tissue injury leads to local increase of blood flow, resulting in an increase of transport of immunocompetent cells, proteins, and oxygen to the site of injury and enhancing the processes of healing.

  8. Inhibition of CaMKK2 Stimulates Osteoblast Formation and Inhibits Osteoclast Differentiation

    PubMed Central

    Cary, Rachel L.; Waddell, Seid; Racioppi, Luigi; Long, Fanxin; Novack, Deborah V.; Voor, Michael J.; Sankar, Uma

    2013-01-01

    Bone remodeling, a physiological process characterized by bone formation by osteoblasts (OB) and resorption of pre-existing bone matrix by osteoclasts (OC), is vital for the maintenance of healthy bone tissue in adult humans. Imbalances in this vital process result in pathological conditions including osteoporosis. Owing to its initial asymptomatic nature, osteoporosis is often detected only after the patient has sustained significant bone loss or a fracture. Hence, anabolic therapeutics that stimulates bone accrual is in high clinical demand. Here we identify Ca2+/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) as a potential target for such therapeutics, as its inhibition enhances OB differentiation and bone growth and suppresses OC differentiation. Mice null for CaMKK2 possess higher trabecular bone mass in their long bones, along with significantly more OBs and fewer multinuclear OCs. Whereas Camkk2−/− MSCs yield significantly higher numbers of OBs, bone marrow cells from Camkk2−/− mice produce fewer multinuclear OCs, in vitro. Acute inhibition of CaMKK2 by its selective, cell-permeable pharmacological inhibitor STO-609 also results in increased OB and diminished OC formation. Further, we find phospho-protein kinase A (PKA) and Ser133 phosphorylated form of cyclic adenosine monophosphate (cAMP) response element binding protein (pCREB) to be markedly elevated in OB progenitors deficient in CaMKK2. On the other hand, genetic ablation of CaMKK2 or its pharmacological inhibition in OC progenitors results in reduced pCREB as well as significantly reduced levels of its transcriptional target, nuclear factor of activated T cells c1 (NFATc1). Moreover, in vivo administration of STO-609 results in increased OBs and diminished OCs, conferring significant protection from ovariectomy (OVX)-induced osteoporosis in adult mice. Overall, our findings reveal a novel function for CaMKK2 in bone remodeling and highlight the potential for its therapeutic

  9. Copper Regulates Cyclic AMP-Dependent Lipolysis

    PubMed Central

    Krishnamoorthy, Lakshmi; Cotruvo, Joseph A.; Chan, Jefferson; Kaluarachchi, Harini; Muchenditsi, Abigael; Pendyala, Venkata S.; Jia, Shang; Aron, Allegra T.; Ackerman, Cheri M.; Vander Wal, Mark N.; Guan, Timothy; Smaga, Lukas P.; Farhi, Samouil L.; New, Elizabeth J.; Lutsenko, Svetlana; Chang, Christopher J.

    2016-01-01

    Cell signaling relies extensively on dynamic pools of redox-inactive metal ions such as sodium, potassium, calcium, and zinc, but their redox-active transition metal counterparts such as copper and iron have been studied primarily as static enzyme cofactors. Here we report that copper is an endogenous regulator of lipolysis, the breakdown of fat, which is an essential process in maintaining the body's weight and energy stores. Utilizing a murine model of genetic copper misregulation, in combination with pharmacological alterations in copper status and imaging studies in a 3T3-L1 white adipocyte model, we demonstrate that copper regulates lipolysis at the level of the second messenger, cyclic AMP (cAMP), by altering the activity of the cAMP-degrading phosphodiesterase PDE3B. Biochemical studies of the copper-PDE3B interaction establish copper-dependent inhibition of enzyme activity and identify a key conserved cysteine residue within a PDE3-specific loop that is essential for the observed copper-dependent lipolytic phenotype. PMID:27272565

  10. Effects of Eucommia leaf extracts on autonomic nerves, body temperature, lipolysis, food intake, and body weight.

    PubMed

    Horii, Yuko; Tanida, Mamoru; Shen, Jiao; Hirata, Tetsuya; Kawamura, Naomi; Wada, Atsunori; Nagai, Katsuya

    2010-08-02

    Eucommia ulmoides Oliver leaf extracts (ELE) have been shown to exert a hypolipidemic effect in hamsters. Therefore, it was hypothesized that ELE might affect lipid metabolism via changes in autonomic nerve activities and causes changes in thermogenesis and body weight. We examined this hypothesis, and found that intraduodenal (ID) injection of ELE elevated epididymal white adipose tissue sympathetic nerve activity (WAT-SNA) and interscapular brown adipose tissue sympathetic nerve activity (BAT-SNA) in urethane-anesthetized rats and elevated the plasma concentration of free fatty acids (FFA) (a marker of lipolysis) and body temperature (BT) (a marker of thermogenesis) in conscious rats. Furthermore, it was observed that ID administration of ELE decreased gastric vagal nerve activity (GVNA) in urethane-anesthetized rats, and that ELE given as food reduced food intake, body and abdominal adipose tissue weights and decreased plasma triglyceride level. These findings suggest that ELE stimulates lipolysis and thermogenesis through elevations in WAT-SNA and BAT-SNA, respectively, suppresses appetite by inhibiting the activities of the parasympathetic nerves innervating the gastrointestinal tract, including GVNA, and decreases the amount of abdominal fat and body weight via these changes.

  11. Imatinib mesylate inhibits platelet derived growth factor stimulated proliferation of rheumatoid synovial fibroblasts

    SciTech Connect

    Sandler, Charlotta; Joutsiniemi, Saima; Lindstedt, Ken A.; Juutilainen, Timo; Kovanen, Petri T.; Eklund, Kari K. . E-mail: kari.eklund@hus.fi

    2006-08-18

    Synovial fibroblast is the key cell type in the growth of the pathological synovial tissue in arthritis. Here, we show that platelet-derived growth factor (PDGF) is a potent mitogen for synovial fibroblasts isolated from patients with rheumatoid arthritis. Inhibition of PDGF-receptor signalling by imatinib mesylate (1 {mu}M) completely abrogated the PDGF-stimulated proliferation and inhibited approximately 70% of serum-stimulated proliferation of synovial fibroblasts. Similar extent of inhibition was observed when PDGF was neutralized with anti-PDGF antibodies, suggesting that imatinib mesylate does not inhibit pathways other than those mediated by PDGF-receptors. No signs of apoptosis were detected in synovial fibroblasts cultured in the presence of imatinib. These results suggest that imatinib mesylate specifically inhibits PDGF-stimulated proliferation of synovial fibroblasts, and that inhibition of PDGF-receptors could represent a feasible target for novel antirheumatic therapies.

  12. Modulation of motor inhibition by subthalamic stimulation in obsessive-compulsive disorder

    PubMed Central

    Kibleur, A; Gras-Combe, G; Benis, D; Bastin, J; Bougerol, T; Chabardès, S; Polosan, M; David, O

    2016-01-01

    High-frequency deep brain stimulation of the subthalamic nucleus can be used to treat severe obsessive-compulsive disorders that are refractory to conventional treatments. The mechanisms of action of this approach possibly rely on the modulation of associative-limbic subcortical–cortical loops, but remain to be fully elucidated. Here in 12 patients, we report the effects of high-frequency stimulation of the subthalamic nucleus on behavior, and on electroencephalographic responses and inferred effective connectivity during motor inhibition processes involved in the stop signal task. First, we found that patients were faster to respond and had slower motor inhibition processes when stimulated. Second, the subthalamic stimulation modulated the amplitude and delayed inhibition-related electroencephalographic responses. The power of reconstructed cortical current densities decreased in the stimulation condition in a parietal–frontal network including cortical regions of the inhibition network such as the superior parts of the inferior frontal gyri and the dorsolateral prefrontal cortex. Finally, dynamic causal modeling revealed that the subthalamic stimulation was more likely to modulate efferent connections from the basal ganglia, modeled as a hidden source, to the cortex. The connection from the basal ganglia to the right inferior frontal gyrus was significantly decreased by subthalamic stimulation. Beyond motor inhibition, our study thus strongly suggests that the mechanisms of action of high-frequency subthalamic stimulation are not restricted to the subthalamic nucleus, but also involve the modulation of distributed subcortical–cortical networks. PMID:27754484

  13. Facilitation and inhibition in the visual system after photic stimulation.

    NASA Technical Reports Server (NTRS)

    Cavaggioni, A.; Goldstein, M. H., Jr.

    1965-01-01

    Changes in shock-evoked response complex /SERC/ RECORDED from visual cortexes of cats after retinal illumination, noting enhancement of waveform after photic stimulation and role of barbiturate anesthetization

  14. Basic study on the influence of inhibition induced by the magnetic stimulation on the peripheral nerve

    NASA Astrophysics Data System (ADS)

    Sato, Aya; Torii, Tetsuya; Iwahashi, Masakuni; Iramina, Keiji

    2015-05-01

    The purpose of this study is to analyze the inhibition mechanism of magnetic stimulation on motor function. A magnetic stimulator with a flat figure-eight coil was used to stimulate the peripheral nerve of the antebrachium. The intensity of magnetic stimulation was 0.8 T, and the stimulation frequency was 1 Hz. The amplitudes of the motor-evoked potentials (MEPs) at the abductor pollicis brevis muscle and first dorsal interosseous muscle were used to evaluate the effects of magnetic stimulation. The effects of magnetic stimulation were evaluated by analyzing the MEP amplitude before and after magnetic stimulation to the primary motor cortex. The results showed that MEP amplitude after magnetic stimulation compared with before magnetic stimulation decreased. Because there were individual differences in MEP amplitude induced by magnetic stimulation, the MEP amplitude after stimulation was normalized by the amplitude of each participant before stimulation. The MEP amplitude after stimulation decreased by approximately 58% (p < 0.01) on average compared with before stimulation. Previous studies suggested that magnetic stimulation to the primary motor cortex induced an increase or a decrease in MEP amplitude. Furthermore, previous studies have shown that the alteration in MEP amplitude was induced by cortical excitability based on magnetic stimulation. The results of this study showed that MEP amplitude decreased following magnetic stimulation to the peripheral nerve. We suggest that the decrease in MEP amplitude found in this study was obtained via the feedback from a peripheral nerve through an afferent nerve to the brain. This study suggests that peripheral excitement by magnetic stimulation of the peripheral nerve may control the central nervous system via afferent feedback.

  15. Disruption of latent inhibition by interpolation of task-irrelevant stimulation between preexposure and conditioning.

    PubMed

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R

    2005-08-01

    Latent inhibition refers to attenuated responding to a conditioned stimulus (CS) that was repeatedly presented without reinforcement prior to the CS-unconditioned stimulus (US) pairings. Using water-deprived rats as subjects, we observed that interpolating task-irrelevant stimulation between the preexposure and conditioning phases of a latent inhibition procedure attenuated latent inhibition (Experiments 1A, 1B, and 2). Apparently, interpolated stimulation segments the preexposure and conditioning treatments into two separate experiences, much in the same way that a change of context would. Consistent with this view, the interpolated stimulation did not disrupt latent inhibition if it was also presented during both preexposure and conditioning (Experiment 3). We view these results as analogous to those of Escobar, Arcediano, and Miller (2003), who suggested that the difficulty in observing latent inhibition in human adults is related to the segmentation between preexposure and conditioning caused by the usual interpolation of instructions in preparations with humans.

  16. The Effect of Insulin, TNFα and DHA on the Proliferation, Differentiation and Lipolysis of Preadipocytes Isolated from Large Yellow Croaker (Pseudosciaena Crocea R.)

    PubMed Central

    Wang, Xinxia; Huang, Ming; Wang, Yizhen

    2012-01-01

    Fish final product can be affected by excessive lipid accumulation. Therefore, it is important to develop strategies to control obesity in cultivated fish to strengthen the sustainability of the aquaculture industry. As in mammals, the development of adiposity in fish depends on hormonal, cytokine and dietary factors. In this study, we investigated the proliferation and differentiation of preadipocytes isolated from the large yellow croaker and examined the effects of critical factors such as insulin, TNFα and DHA on the proliferation, differentiation and lipolysis of adipocytes. Preadipocytes were isolated by collagenase digestion, after which their proliferation was evaluated. The differentiation process was optimized by assaying glycerol-3-phosphate dehydrogenase (GPDH) activity. Oil red O staining and electron microscopy were performed to visualize the accumulated triacylglycerol. Gene transcript levels were measured using SYBR green quantitative real-time PCR. Insulin promoted preadipocytes proliferation, stimulated cell differentiation and decreased lipolysis of mature adipocytes. TNFα and DHA inhibited cell proliferation and differentiation. While TNFα stimulated mature adipocyte lipolysis, DHA showed no lipolytic effect on adipocytes. The expressions of adipose triglyceride lipase (ATGL), fatty acid synthase (FAS), lipoprotein lipase (LPL) and peroxisome proliferator-activated receptor α, γ (PPARα, PPARγ) were quantified during preadipocytes differentiation and adipocytes lipolysis to partly explain the regulation mechanisms. In summary, the results of this study indicated that although preadipocytes proliferation and the differentiation process in large yellow croaker are similar to these processes in mammals, the effects of critical factors such as insulin, TNFα and DHA on fish adipocytes development are not exactly the same. Our findings fill in the gaps in the basic data regarding the effects of critical factors on adiposity development in fish

  17. Effects of Genetic Loci Associated with Central Obesity on Adipocyte Lipolysis

    PubMed Central

    Strawbridge, Rona J.; Laumen, Helmut; Hamsten, Anders; Breier, Michaela; Grallert, Harald; Hauner, Hans; Arner, Peter; Dahlman, Ingrid

    2016-01-01

    Objectives Numerous genetic loci have been associated with measures of central fat accumulation, such as waist-to-hip ratio adjusted for body mass index (WHRadjBMI). However the mechanisms by which genetic variations influence obesity remain largely elusive. Lipolysis is a key process for regulation of lipid storage in adipocytes, thus is implicated in obesity and its metabolic complications. Here, genetic variants at 36 WHRadjBMI-associated loci were examined for their influence on abdominal subcutaneous adipocyte lipolysis. Subjects and Methods Fasting subcutaneous adipose tissue biopsies were collected from 789 volunteers (587 women and 202 men, body mass index (BMI) range 17.7–62.3 kg/m2). We quantified subcutaneous adipocyte lipolysis, both spontaneous and stimulated by the catecholamine isoprenaline or a cyclic AMP analogue. DNA was extracted from peripheral blood mononuclear cells and genotyping of SNPs associated with WHRadjBMI conducted. The effects on adipocyte lipolysis measures were assessed for SNPs individually and combined in a SNP score. Results The WHRadjBMI-associated loci CMIP, PLXND1, VEGFA and ZNRF3-KREMEN1 demonstrated nominal associations with spontaneous and/or stimulated lipolysis. Candidate genes in these loci have been reported to influence NFκB-signaling, fat cell size and Wnt signalling, all of which may influence lipolysis. Significance This report provides evidence for specific WHRadjBMI-associated loci as candidates to modulate adipocyte lipolysis. Additionally, our data suggests that genetically increased central fat accumulation is unlikely to be a major cause of altered lipolysis in abdominal adipocytes. PMID:27104953

  18. Is transcranial direct current stimulation a potential method for improving response inhibition?

    PubMed

    Kwon, Yong Hyun; Kwon, Jung Won

    2013-04-15

    Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the transcranial direct-current stimulation condition or a sham-transcranial direct-current stimulation condition. All subjects consecutively performed the stop-signal task before, during, and after the delivery of anodal transcranial direct-current stimulation over the pre-supplementary motor area (pre-transcranial direct-current stimulation phase, transcranial direct-current stimulation phase, and post-transcranial direct-current stimulation phase). Compared to the sham condition, there were significant reductions in the stop-signal processing times during and after transcranial direct-current stimulation, and change times were significantly greater in the transcranial direct-current stimulation condition. There was no significant change in go processing-times during or after transcranial direct-current stimulation in either condition. Anodal transcranial direct-current stimulation was feasibly coupled to an interactive improvement in inhibitory control. This coupling led to a decrease in the stop-signal process time required for the appropriate responses between motor execution and inhibition. However, there was no transcranial direct-current stimulation effect on the no-signal reaction time during the stop-signal task. Transcranial direct-current stimulation can adjust certain behaviors, and it could be a useful clinical intervention for patients who have difficulties with response inhibition.

  19. Insulin Regulates Adipocyte Lipolysis via an Akt-Independent Signaling Pathway ▿

    PubMed Central

    Choi, Sarah M.; Tucker, David F.; Gross, Danielle N.; Easton, Rachael M.; DiPilato, Lisa M.; Dean, Abigail S.; Monks, Bob R.; Birnbaum, Morris J.

    2010-01-01

    After a meal, insulin suppresses lipolysis through the activation of its downstream kinase, Akt, resulting in the inhibition of protein kinase A (PKA), the main positive effector of lipolysis. During insulin resistance, this process is ineffective, leading to a characteristic dyslipidemia and the worsening of impaired insulin action and obesity. Here, we describe a noncanonical Akt-independent, phosphoinositide-3 kinase (PI3K)-dependent pathway that regulates adipocyte lipolysis using restricted subcellular signaling. This pathway selectively alters the PKA phosphorylation of its major lipid droplet-associated substrate, perilipin. In contrast, the phosphorylation of another PKA substrate, hormone-sensitive lipase (HSL), remains Akt dependent. Furthermore, insulin regulates total PKA activity in an Akt-dependent manner. These findings indicate that localized changes in insulin action are responsible for the differential phosphorylation of PKA substrates. Thus, we identify a pathway by which insulin regulates lipolysis through the spatially compartmentalized modulation of PKA. PMID:20733001

  20. Insulin regulates adipocyte lipolysis via an Akt-independent signaling pathway.

    PubMed

    Choi, Sarah M; Tucker, David F; Gross, Danielle N; Easton, Rachael M; DiPilato, Lisa M; Dean, Abigail S; Monks, Bob R; Birnbaum, Morris J

    2010-11-01

    After a meal, insulin suppresses lipolysis through the activation of its downstream kinase, Akt, resulting in the inhibition of protein kinase A (PKA), the main positive effector of lipolysis. During insulin resistance, this process is ineffective, leading to a characteristic dyslipidemia and the worsening of impaired insulin action and obesity. Here, we describe a noncanonical Akt-independent, phosphoinositide-3 kinase (PI3K)-dependent pathway that regulates adipocyte lipolysis using restricted subcellular signaling. This pathway selectively alters the PKA phosphorylation of its major lipid droplet-associated substrate, perilipin. In contrast, the phosphorylation of another PKA substrate, hormone-sensitive lipase (HSL), remains Akt dependent. Furthermore, insulin regulates total PKA activity in an Akt-dependent manner. These findings indicate that localized changes in insulin action are responsible for the differential phosphorylation of PKA substrates. Thus, we identify a pathway by which insulin regulates lipolysis through the spatially compartmentalized modulation of PKA.

  1. Epidermal growth factor (EGF) inhibits stimulated thyroid hormone secretion in the mouse

    SciTech Connect

    Ahren, B.

    1987-07-01

    It is known that epidermal growth factor (EGF) inhibits iodide uptake in the thyroid follicular cells and lowers plasma levels of thyroid hormones upon infusion into sheep and ewes. In this study, the effects of EGF on basal and stimulated thyroid hormone secretion were investigated in the mouse. Mice were pretreated with /sup 125/I and thyroxine; the subsequent release of /sup 125/I is an estimation of thyroid hormone secretion. It was found that basal radioiodine secretion was not altered by intravenous injection of EGF (5 micrograms/animal). However, the radioiodine secretion stimulated by both TSH (120 microU/animal) and vasoactive intestinal peptide (VIP; 5 micrograms/animal) were inhibited by EGF (5 micrograms/animal). At a lower dose level (0.5 microgram/animal), EGF had no influence on stimulated radioiodine secretion. In conclusion, EGF inhibits stimulated thyroid hormone secretion in the mouse.

  2. CD36 level and trafficking are determinants of lipolysis in adipocytes.

    PubMed

    Zhou, Dequan; Samovski, Dmitri; Okunade, Adewole L; Stahl, Philip D; Abumrad, Nada A; Su, Xiong

    2012-11-01

    CD36 has been linked to the etiology of insulin resistance and inflammation. We explored its function in regulating adipose tissue lipolysis, which influences fat accumulation by liver and muscle and overall metabolism. Knockdown of CD36 in differentiated 3T3-L1 adipocytes decreased lipolysis in response to 10 μM of the β-adrenergic agonist isoproterenol (by 42%), 10 μM of the adenyl cyclase activator forskolin (by 32%), and 500 μM of the phosphodiesterase (PDE) inhibitor isobutylmethylxanthine (by 33%). All three treatments in the knockdown adipocytes were associated with significant decreases of cAMP levels and of the hormone-sensitive lipase (HSL) and perilipin phosphorylation. An important role for PDE was supported by the lack of inhibition of the lipolysis induced by the poorly hydrolyzable dibutyryl cAMP analog. An additional contributory mechanism was diminished activation of the Src-ERK1/2 pathway. Regulation of lipolysis and lipolytic signaling by CD36 was reproduced with adipose tissue from CD36(-/-) mice. The importance of surface CD36 in this regulation was suggested by the finding that the plasma membrane-impermeable CD36 inhibitor sulfo-N-succinimidyl oleate (20 μM) decreased lipolysis. Interestingly, isoproterenol induced CD36 internalization, and this process was blocked by HSL inhibition, suggesting feedback regulation of adipocyte lipolysis via CD36 trafficking.

  3. Splanchnic lipolysis in human obesity

    PubMed Central

    Nielsen, Soren; Guo, ZengKui; Johnson, C. Michael; Hensrud, Donald D.; Jensen, Michael D.

    2004-01-01

    Elevated FFA concentrations have been shown to reproduce some of the metabolic abnormalities of obesity. It has been hypothesized that visceral adipose tissue lipolysis releases excess FFAs into the portal vein, exposing the liver to higher FFA concentrations. We used isotope dilution/hepatic vein catheterization techniques to examine whether intra-abdominal fat contributes a greater portion of hepatic FFA delivery in visceral obesity. Obese women (n = 24) and men (n = 20) with a range of obesity phenotypes, taken together with healthy, lean women (n = 12) and men (n = 12), were studied. Systemic, splanchnic, and leg FFA kinetics were measured. The results showed that plasma FFA concentrations were approximately 20% greater in obese men and obese women. The contribution of splanchnic lipolysis to hepatic FFA delivery ranged from less than 10% to almost 50% and increased as a function of visceral fat in women (r = 0.49, P = 0.002) and in men (r = 0.52, P = 0.002); the slope of the relationship was greater in women than in men (P < 0.05). Leg and splanchnic tissues contributed a greater portion of systemic FFA release in obese men and women than in lean men and women. We conclude that the contribution of visceral adipose tissue lipolysis to hepatic FFA delivery increases with increasing visceral fat in humans and that this effect is greater in women than in men. PMID:15173884

  4. Regional acidosis locally inhibits but remotely stimulates Ca2+ waves in ventricular myocytes.

    PubMed

    Ford, Kerrie L; Moorhouse, Emma L; Bortolozzi, Mario; Richards, Mark A; Swietach, Pawel; Vaughan-Jones, Richard D

    2017-07-01

    Spontaneous Ca2+ waves in cardiomyocytes are potentially arrhythmogenic. A powerful controller of Ca2+ waves is the cytoplasmic H+ concentration ([H+]i), which fluctuates spatially and temporally in conditions such as myocardial ischaemia/reperfusion. H+-control of Ca2+ waves is poorly understood. We have therefore investigated how [H+]i co-ordinates their initiation and frequency. Spontaneous Ca2+ waves were imaged (fluo-3) in rat isolated ventricular myocytes, subjected to modest Ca2+-overload. Whole-cell intracellular acidosis (induced by acetate-superfusion) stimulated wave frequency. Pharmacologically blocking sarcolemmal Na+/H+ exchange (NHE1) prevented this stimulation, unveiling inhibition by H+. Acidosis also increased Ca2+ wave velocity. Restricting acidosis to one end of a myocyte, using a microfluidic device, inhibited Ca2+ waves in the acidic zone (consistent with ryanodine receptor inhibition), but stimulated wave emergence elsewhere in the cell. This remote stimulation was absent when NHE1 was selectively inhibited in the acidic zone. Remote stimulation depended on a locally evoked, NHE1-driven rise of [Na+]i that spread rapidly downstream. Acidosis influences Ca2+ waves via inhibitory Hi+ and stimulatory Nai+ signals (the latter facilitating intracellular Ca2+-loading through modulation of sarcolemmal Na+/Ca2+ exchange activity). During spatial [H+]i-heterogeneity, Hi+-inhibition dominates in acidic regions, while rapid Nai+ diffusion stimulates waves in downstream, non-acidic regions. Local acidosis thus simultaneously inhibits and stimulates arrhythmogenic Ca2+-signalling in the same myocyte. If the principle of remote H+-stimulation of Ca2+ waves also applies in multicellular myocardium, it raises the possibility of electrical disturbances being driven remotely by adjacent ischaemic areas, which are known to be intensely acidic.

  5. Vagus nerve stimulation inhibits cytokine production and attenuates disease severity in rheumatoid arthritis

    PubMed Central

    Koopman, Frieda A.; Chavan, Sangeeta S.; Miljko, Sanda; Grazio, Simeon; Sokolovic, Sekib; Schuurman, P. Richard; Mehta, Ashesh D.; Levine, Yaakov A.; Faltys, Michael; Zitnik, Ralph; Tracey, Kevin J.; Tak, Paul P.

    2016-01-01

    Rheumatoid arthritis (RA) is a heterogeneous, prevalent, chronic autoimmune disease characterized by painful swollen joints and significant disabilities. Symptomatic relief can be achieved in up to 50% of patients using biological agents that inhibit tumor necrosis factor (TNF) or other mechanisms of action, but there are no universally effective therapies. Recent advances in basic and preclinical science reveal that reflex neural circuits inhibit the production of cytokines and inflammation in animal models. One well-characterized cytokine-inhibiting mechanism, termed the “inflammatory reflex,” is dependent upon vagus nerve signals that inhibit cytokine production and attenuate experimental arthritis severity in mice and rats. It previously was unknown whether directly stimulating the inflammatory reflex in humans inhibits TNF production. Here we show that an implantable vagus nerve-stimulating device in epilepsy patients inhibits peripheral blood production of TNF, IL-1β, and IL-6. Vagus nerve stimulation (up to four times daily) in RA patients significantly inhibited TNF production for up to 84 d. Moreover, RA disease severity, as measured by standardized clinical composite scores, improved significantly. Together, these results establish that vagus nerve stimulation targeting the inflammatory reflex modulates TNF production and reduces inflammation in humans. These findings suggest that it is possible to use mechanism-based neuromodulating devices in the experimental therapy of RA and possibly other autoimmune and autoinflammatory diseases. PMID:27382171

  6. High and low frequency transcutaneous electrical nerve stimulation inhibits nociceptive responses induced by CO2 laser stimulation in humans.

    PubMed

    de Tommaso, Marina; Fiore, Pietro; Camporeale, Alfonso; Guido, Marco; Libro, Giuseppe; Losito, Luciana; Megna, Marisa; Puca, Francomichele; Megna, Gianfranco

    2003-05-15

    The aim of the study was to evaluate the effects of transcutaneous electric nerve stimulation (TENS) on CO(2) laser evoked potentials (LEPs) in 16 normal subjects. The volar side of the forearm was stimulated by 10 Hz TENS in eight subjects and by 100 Hz TENS in the remainder; the skin of the forearm was stimulated by CO(2) laser and the LEPs were recorded in basal conditions and soon after and 15 min after TENS. Both low and high frequency TENS significantly reduced the subjective rating of heat stimuli and the LEPs amplitude, although high frequency TENS appeared more efficacious. TENS seemed to exert a mild inhibition of the perception and processing of pain induced by laser Adelta fibres activation; the implications of these effects in the clinical employment of TENS remain to be clarified.

  7. Phorbol ester stimulates secretory activity while inhibiting receptor-activated aminopyrine uptake by gastric glands

    SciTech Connect

    Brown, M.R.; Chew, C.S.

    1986-03-05

    Both cyclic AMP-dependent and -independent secretagogues stimulate pepsinogen release, respiration and H/sup +/ secretory activity (AP uptake) in rabbit gastric glands. 12-O-tetradecanoylphorbol-13-acetate (T), a diacyglycerol analog, activates protein kinase C (PKC) and stimulates secretion in many systems. T stimulated respiration and pepsinogen release by glands and increased AP uptake by both glands and purified parietal cells. However, T reduced AP uptake by glands stimulated with carbachol (C) or histamine (H) with an apparent IC/sub 50/ of 1 nM. Preincubation with T for 30 min produced maximum inhibition which was not reversed by removal of T. T accelerated the decline of the transient C peak while the late steady state response to H was most inhibited. H-stimulated AP uptake was also inhibited by 50 ..mu..g/ml 1-oleoyl-2-acetyl-glycerol, a reported PKC activator, but not by the inactive phorbol, 4..cap alpha..-phorbol-12,13-didecanoate. In contrast, T potentiated AP uptake by glands stimulated with submaximal doses of dibutyryl cyclic AMP. These results suggest inhibition by T is a specific effect of PKC activators. The differing effects of T on secretion indicators may result from a dual action of T on receptor and post-receptor intracellular events.

  8. Lipolysis sensation by white fat afferent nerves triggers brown fat thermogenesis.

    PubMed

    Garretson, John T; Szymanski, Laura A; Schwartz, Gary J; Xue, Bingzhong; Ryu, Vitaly; Bartness, Timothy J

    2016-08-01

    Metabolic challenges, such as a cold environment, stimulate sympathetic neural efferent activity to white adipose tissue (WAT) to drive lipolysis, thereby increasing the availability of free fatty acids as one source of fuel for brown adipose tissue (BAT) thermogenesis. WAT is also innervated by sensory nerve fibers that network to metabolic brain areas; moreover, activation of these afferents is reported to increase sympathetic nervous system outflow. However, the endogenous stimuli sufficient to drive WAT afferents during metabolic challenges as well as their functional relation to BAT thermogenesis remain unknown. We tested if local WAT lipolysis directly activates WAT afferent nerves, and then assessed whether this WAT sensory signal affected BAT thermogenesis in Siberian hamsters (Phodopus sungorus). 2-deoxyglucose, a sympathetic nervous system stimulant, caused β-adrenergic receptor dependent increases in inguinal WAT (IWAT) afferent neurophysiological activity. In addition, direct IWAT injections of the β3-AR agonist CL316,243 dose-dependently increased: 1) phosphorylation of IWAT hormone sensitive lipase, an indicator of SNS-stimulated lipolysis, 2) expression of the neuronal activation marker c-Fos in dorsal root ganglion neurons receiving sensory input from IWAT, and 3) IWAT afferent neurophysiological activity, an increase blocked by antilipolytic agent 3,5-dimethylpyrazole. Finally, we demonstrated that IWAT afferent activation by lipolysis triggers interscapular BAT thermogenesis through a neural link between these two tissues. These data suggest IWAT lipolysis activates local IWAT afferents triggering a neural circuit from WAT to BAT that acutely induces BAT thermogenesis.

  9. Lipid Droplet Protein LID-1 Mediates ATGL-1-Dependent Lipolysis during Fasting in Caenorhabditis elegans

    PubMed Central

    Lee, Jung Hyun; Kong, Jinuk; Jang, Ju Yeon; Han, Ji Seul; Ji, Yul; Lee, Junho

    2014-01-01

    Lipolysis is a delicate process involving complex signaling cascades and sequential enzymatic activations. In Caenorhabditis elegans, fasting induces various physiological changes, including a dramatic decrease in lipid contents through lipolysis. Interestingly, C. elegans lacks perilipin family genes which play a crucial role in the regulation of lipid homeostasis in other species. Here, we demonstrate that in the intestinal cells of C. elegans, a newly identified protein, lipid droplet protein 1 (C25A1.12; LID-1), modulates lipolysis by binding to adipose triglyceride lipase 1 (C05D11.7; ATGL-1) during nutritional deprivation. In fasted worms, lipid droplets were decreased in intestinal cells, whereas suppression of ATGL-1 via RNA interference (RNAi) resulted in retention of stored lipid droplets. Overexpression of ATGL-1 markedly decreased lipid droplets, whereas depletion of LID-1 via RNAi prevented the effect of overexpressed ATGL-1 on lipolysis. In adult worms, short-term fasting increased cyclic AMP (cAMP) levels, which activated protein kinase A (PKA) to stimulate lipolysis via ATGL-1 and LID-1. Moreover, ATGL-1 protein stability and LID-1 binding were augmented by PKA activation, eventually leading to increased lipolysis. These data suggest the importance of the concerted action of lipase and lipid droplet protein in the response to fasting signals via PKA to maintain lipid homeostasis. PMID:25202121

  10. Apoptosis inhibitor of macrophage (AIM) diminishes lipid droplet-coating proteins leading to lipolysis in adipocytes.

    PubMed

    Iwamura, Yoshihiro; Mori, Mayumi; Nakashima, Katsuhiko; Mikami, Toshiyuki; Murayama, Katsuhisa; Arai, Satoko; Miyazaki, Toru

    2012-06-08

    Under fasting conditions, triacylglycerol in adipose tissue undergoes lipolysis to supply fatty acids as energy substrates. Such lipolysis is regulated by hormones, which activate lipases via stimulation of specific signalling cascades. We previously showed that macrophage-derived soluble protein, AIM induces obesity-associated lipolysis, triggering chronic inflammation in fat tissue which causes insulin resistance. However, the mechanism of how AIM mediates lipolysis remains unknown. Here we show that AIM induces lipolysis in a manner distinct from that of hormone-dependent lipolysis, without activation or augmentation of lipases. In vivo and in vitro, AIM did not enhance phosphorylation of hormone-sensitive lipase (HSL) in adipocytes, a hallmark of hormone-dependent lipolysis activation. Similarly, adipose tissue from obese AIM-deficient and wild-type mice showed comparable HSL phosphorylation. Consistent with the suppressive effect of AIM on fatty acid synthase activity, the amount of saturated and unsaturated fatty acids was reduced in adipocytes treated with AIM. This response ablated transcriptional activity of peroxisome proliferator-activated receptor (PPARγ), leading to diminished gene expression of lipid-droplet coating proteins including fat-specific protein 27 (FSP27) and Perilipin, which are indispensable for triacylglycerol storage in adipocytes. Accordingly, the lipolytic effect of AIM was overcome by a PPARγ-agonist or forced expression of FSP27, while it was synergized by a PPARγ-antagonist. Overall, distinct modes of lipolysis appear to take place in different physiological situations; one is a supportive response against nutritional deprivation achieved by enhancing lipase activity, and the other is a pathological consequence of obesity, causing subclinical inflammation and metabolic disorders, mediated by abolishing droplet-coating proteins. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Low Frequency Electrical Stimulation Either Prior to Or after Rapid Kindling Stimulation Inhibits the Kindling-Induced Epileptogenesis

    PubMed Central

    Jalilifar, Mostafa; Moazedi, Ahmad Ali; Ghotbeddin, Zohreh

    2017-01-01

    Objective. Studies are ongoing to find appropriate low frequency stimulation (LFS) protocol for treatment of epilepsy. The present study aimed at assessing the antiepileptogenesis effects of LFS with the same protocol applied either just before or immediately after kindling stimulations. Method. This experimental animal study was conducted on adult Wistar rats (200 ± 20 g) randomly divided into kindle (n = 7), LFS + Kindle (n = 6), and Kindle + LFS groups (n = 6). All animals underwent rapid kindling procedure and four packages of LFS (1 Hz) with 5 min interval were applied either immediately before (LFS-K) or after kindling stimulation (K-LFS). The after discharge duration (ADD), daily stages of kindling, and kindling seizure stage and number of stimulations required to reach each stage were compared between the three groups using two-way analysis of variance (ANOVA) followed by Tukey post hoc and one-way ANOVA, and Kruskal-Wallis test, respectively. Results. LFS in both protocols significantly decreased the ADD (p < 0.05) and daily seizure stages (p < 0.05) and increased the number of stimulations required to achieve stage 3 and stages 4 and 5 of kindling compared with the kindle group (stage 2: p > 0.05, stages 3 to 5: p < 0.05). Conclusion. Although LFS-K showed more inhibiting effect than K-LFS, the difference was not statistically significant. PMID:28373988

  12. Apoptosis inhibitor of macrophage (AIM) diminishes lipid droplet-coating proteins leading to lipolysis in adipocytes

    SciTech Connect

    Iwamura, Yoshihiro; Mori, Mayumi; Nakashima, Katsuhiko; Mikami, Toshiyuki; Murayama, Katsuhisa; Arai, Satoko; Miyazaki, Toru

    2012-06-08

    Highlights: Black-Right-Pointing-Pointer AIM induces lipolysis in a distinct manner from that of hormone-dependent lipolysis. Black-Right-Pointing-Pointer AIM ablates activity of peroxisome proliferator-activated receptor in adipocytes. Black-Right-Pointing-Pointer AIM reduces mRNA levels of lipid-droplet coating proteins leading to lipolysis. -- Abstract: Under fasting conditions, triacylglycerol in adipose tissue undergoes lipolysis to supply fatty acids as energy substrates. Such lipolysis is regulated by hormones, which activate lipases via stimulation of specific signalling cascades. We previously showed that macrophage-derived soluble protein, AIM induces obesity-associated lipolysis, triggering chronic inflammation in fat tissue which causes insulin resistance. However, the mechanism of how AIM mediates lipolysis remains unknown. Here we show that AIM induces lipolysis in a manner distinct from that of hormone-dependent lipolysis, without activation or augmentation of lipases. In vivo and in vitro, AIM did not enhance phosphorylation of hormone-sensitive lipase (HSL) in adipocytes, a hallmark of hormone-dependent lipolysis activation. Similarly, adipose tissue from obese AIM-deficient and wild-type mice showed comparable HSL phosphorylation. Consistent with the suppressive effect of AIM on fatty acid synthase activity, the amount of saturated and unsaturated fatty acids was reduced in adipocytes treated with AIM. This response ablated transcriptional activity of peroxisome proliferator-activated receptor (PPAR{gamma}), leading to diminished gene expression of lipid-droplet coating proteins including fat-specific protein 27 (FSP27) and Perilipin, which are indispensable for triacylglycerol storage in adipocytes. Accordingly, the lipolytic effect of AIM was overcome by a PPAR{gamma}-agonist or forced expression of FSP27, while it was synergized by a PPAR{gamma}-antagonist. Overall, distinct modes of lipolysis appear to take place in different physiological

  13. Effects of emulsifier charge and concentration on pancreatic lipolysis: 2. Interplay of emulsifiers and biles.

    PubMed

    Vinarov, Zahari; Tcholakova, Slavka; Damyanova, Borislava; Atanasov, Yasen; Denkov, Nikolai D; Stoyanov, Simeon D; Pelan, Edward; Lips, Alex

    2012-08-21

    As a direct continuation of the first part of our in vitro study (Vinarov et al., Langmuir 2012, 28, 8127), here we investigate the effects of emulsifier type and concentration on the degree of triglyceride lipolysis, in the presence of bile salts. Three types of surfactants are tested as emulsifiers: anionic, nonionic, and cationic. For all systems, we observe three regions in the dependence degree of fat lipolysis, α, versus emulsifier-to-bile ratio, f(s): α is around 0.5 in Region 1 (f(s) < 0.02); α passes through a maximum close to 1 in Region 2 (0.02 < f(s) < f(TR)); α is around zero in Region 3 (f(s) > f(TR)). The threshold ratio for complete inhibition of lipolysis, f(TR), is around 0.4 for the nonionic, 1.5 for the cationic, and 7.5 for the anionic surfactants. Measurements of interfacial tensions and optical observations revealed the following: In Region 1, the emulsifier molecules are solubilized in the bile micelles, and the adsorption layer is dominated by bile molecules. In Region 2, mixed surfactant-bile micelles are formed, with high solubilization capacity for the products of triglyceride lipolysis; rapid solubilization of these products leads to complete lipolysis. In Region 3, the emulsifier molecules prevail in the adsorption layer and completely block the lipolysis.

  14. GABA-mediated oxytocinergic inhibition in dorsal horn neurons by hypothalamic paraventricular nucleus stimulation.

    PubMed

    Rojas-Piloni, Gerardo; López-Hidalgo, Mónica; Martínez-Lorenzana, Guadalupe; Rodríguez-Jiménez, Javier; Condés-Lara, Miguel

    2007-03-16

    In anaesthetized rats, we tested whether the unit activity of dorsal horn neurons that receive nociceptive input is modulated by electrical stimulation of the hypothalamic paraventricular nucleus (PVN). An electrophysiological mapping of dorsal horn neurons at L3-L4 let us choose cells responding to a receptive field located in the toes region of the left hindpaw. Dorsal horn neurons were classified according to their response properties to peripheral stimulation. Wide Dynamic Range (WDR) cells responding to electrical stimulation of the peripheral receptive field and presenting synaptic input of Adelta, Abeta, and C-fibers were studied. Suspected interneurons that are typically silent and lack peripheral receptive field responses were also analyzed. PVN electrical stimulation inhibits Adelta (-55.0+/-10.2%), C-fiber (-73.1+/-6.7%), and post-discharge (-75.0+/-8.9%) peripheral activation in WDR cells, and silent interneurons were activated. So, this last type of interneuron was called a PVN-ON cell. In WDR cells, the inhibition of peripheral responses caused by PVN stimulation was blocked by intrathecal administration of a specific oxytocin antagonist or bicuculline. However, PVN-ON cell activation was blocked by the same specific oxytocin antagonist, but not by bicuculline. Our results suggest that PVN stimulation inhibits nociceptive peripheral-evoked responses in WDR neurons by a descending oxytocinergic pathway mediated by GABAergic PVN-ON cells. We discuss our observation that the PVN electrical stimulation selectively inhibits Adelta and C-fiber activity without affecting Abeta fibers. We conclude that Adelta and C-fibers receive a presynaptic inhibition mediated by GABA.

  15. Nigericin inhibits insulin-stimulated glucose transport in 3T3-L1 adipocytes.

    PubMed

    Chu, Chih-Ying; Kao, Ying-Shun; Fong, Jim C

    2002-01-01

    We used nigericin, a K+/H+ exchanger, to test whether glucose transport in 3T3-L1 adipocytes was modulated by changes in intracellular pH. Our results showed that nigericin increased basal but decreased insulin-stimulated glucose uptake in a time- and dose-dependent manner. Whereas the basal translocation of GLUT1 was enhanced, insulin-stimulated GLUT4 translocation was inhibited by nigericin. On the other hand, the total amount of neither transporter protein was altered. The finding that insulin-stimulated phosphoinositide 3-kinase (PI 3-kinase) activity was not affected by nigericin implies that nigericin exerted its inhibition at a step downstream of PI 3-kinase activation. At maximal dose, nigericin rapidly lowered cytosolic pH to 6.7; however, this effect was transient and cytosolic pH was back to normal in 20 min. Removal of nigericin from the incubation medium after 20 min abolished its enhancing effect on basal but had little influence on its inhibition of insulin-stimulated glucose transport. Moreover, lowering cytosolic pH to 6.7 with an exogenously added HCl solution had no effect on glucose transport. Taken together, it appears that nigericin may inhibit insulin-stimulated glucose transport mainly by interfering with GLUT4 translocation, probably by a mechanism not related to changes in cytosolic pH.

  16. Inhibition of forskolin-stimulated adenylate cyclase activity by 5-HT receptor agonists.

    PubMed

    Devivo, M; Maayani, S

    1985-12-17

    We measured the inhibition of forskolin-stimulated adenylate cyclase activity in guinea pig hippocampal membranes by 5-HT, 5-carboxamidotryptamine (CAT) and 8-hydroxy-2-(di-n-propylamino) tetralin (PAT). Low concentrations of these agonists inhibited forskolin-stimulated adenylate cyclase activity in a concentration-dependent and saturable manner. The antagonist spiperone shifted the concentration-response curve to CAT to the right in a parallel manner. The EC50 values of CAT, PAT and 5-HT and the KB of spiperone suggest that this receptor may correspond to the 5-HT1A binding site.

  17. Parathyroid hormone induces adipocyte lipolysis via PKA-mediated phosphorylation of hormone-sensitive lipase.

    PubMed

    Larsson, Sara; Jones, Helena A; Göransson, Olga; Degerman, Eva; Holm, Cecilia

    2016-03-01

    Parathyroid hormone (PTH) is secreted from the parathyroid glands in response to low plasma calcium levels. Besides its classical actions on bone and kidney, PTH may have other important effects, including metabolic effects, as suggested for instance by increased prevalence of insulin resistance and type 2 diabetes in patients with primary hyperparathyroidism. Moreover, secondary hyperparathyroidism may contribute to the metabolic derangements that characterize states of vitamin D deficiency. PTH has been shown to induce adipose tissue lipolysis, but the details of the lipolytic action of PTH have not been described. Here we used primary mouse adipocytes to show that intact PTH (1-84) as well as the N-terminal fragment (1-37) acutely stimulated lipolysis in a dose-dependent manner, whereas the C-terminal fragment (38-84) was without lipolytic effect. The lipolytic action of PTH was paralleled by phosphorylation of known protein kinase A (PKA) substrates, i.e. hormone-sensitive lipase (HSL) and perilipin. The phosphorylation of HSL in response to PTH occurred at the known PKA sites S563 and S660, but not at the non-PKA site S565. PTH-induced lipolysis, as well as phosphorylation of HSL at S563 and S660, was blocked by both the PKA-inhibitor H89 and the adenylate cyclase inhibitor MDL-12330A, whereas inhibitors of extracellular-regulated kinase (ERK), protein kinase B (PKB), AMP-activated protein kinase (AMPK) and Ca(2+)/calmodulin-dependent protein kinase (CaMK) had little or no effect. Inhibition of phosphodiesterase 4 (PDE4) strongly potentiated the lipolytic action of PTH, whereas inhibition of PDE3 had no effect. Our results show that the lipolytic action of PTH is mediated by the PKA signaling pathway with no or minor contribution of other signaling pathways and, furthermore, that the lipolytic action of PTH is limited by simultaneous activation of PDE4. Knowledge of the signaling pathways involved in the lipolytic action of PTH is important for our

  18. G0/G1 switch gene-2 regulates human adipocyte lipolysis by affecting activity and localization of adipose triglyceride lipase

    PubMed Central

    Schweiger, Martina; Paar, Margret; Eder, Christina; Brandis, Janina; Moser, Elena; Gorkiewicz, Gregor; Grond, Susanne; Radner, Franz P. W.; Cerk, Ines; Cornaciu, Irina; Oberer, Monika; Kersten, Sander; Zechner, Rudolf; Zimmermann, Robert; Lass, Achim

    2012-01-01

    The hydrolysis of triglycerides in adipocytes, termed lipolysis, provides free fatty acids as energy fuel. Murine lipolysis largely depends on the activity of adipose triglyceride lipase (ATGL), which is regulated by two proteins annotated as comparative gene identification-58 (CGI-58) and G0/G1 switch gene-2 (G0S2). CGI-58 activates and G0S2 inhibits ATGL activity. In contrast to mice, the functional role of G0S2 in human adipocyte lipolysis is poorly characterized. Here we show that overexpression or silencing of G0S2 in human SGBS adipocytes decreases and increases lipolysis, respectively. Human G0S2 is upregulated during adipocyte differentiation and inhibits ATGL activity in a dose-dependent manner. Interestingly, C-terminally truncated ATGL mutants, which fail to localize to lipid droplets, translocate to the lipid droplet upon coexpression with G0S2, suggesting that G0S2 anchors ATGL to lipid droplets independent of ATGL's C-terminal lipid binding domain. Taken together, our results indicate that G0S2 also regulates human lipolysis by affecting enzyme activity and intracellular localization of ATGL. Increased lipolysis is known to contribute to the pathogenesis of insulin resistance, and G0S2 expression has been shown to be reduced in poorly controlled type 2 diabetic patients. Our data indicate that downregulation of G0S2 in adipose tissue could represent one of the underlying causes leading to increased lipolysis in the insulin-resistant state. PMID:22891293

  19. G0/G1 switch gene-2 regulates human adipocyte lipolysis by affecting activity and localization of adipose triglyceride lipase.

    PubMed

    Schweiger, Martina; Paar, Margret; Eder, Christina; Brandis, Janina; Moser, Elena; Gorkiewicz, Gregor; Grond, Susanne; Radner, Franz P W; Cerk, Ines; Cornaciu, Irina; Oberer, Monika; Kersten, Sander; Zechner, Rudolf; Zimmermann, Robert; Lass, Achim

    2012-11-01

    The hydrolysis of triglycerides in adipocytes, termed lipolysis, provides free fatty acids as energy fuel. Murine lipolysis largely depends on the activity of adipose triglyceride lipase (ATGL), which is regulated by two proteins annotated as comparative gene identification-58 (CGI-58) and G0/G1 switch gene-2 (G0S2). CGI-58 activates and G0S2 inhibits ATGL activity. In contrast to mice, the functional role of G0S2 in human adipocyte lipolysis is poorly characterized. Here we show that overexpression or silencing of G0S2 in human SGBS adipocytes decreases and increases lipolysis, respectively. Human G0S2 is upregulated during adipocyte differentiation and inhibits ATGL activity in a dose-dependent manner. Interestingly, C-terminally truncated ATGL mutants, which fail to localize to lipid droplets, translocate to the lipid droplet upon coexpression with G0S2, suggesting that G0S2 anchors ATGL to lipid droplets independent of ATGL's C-terminal lipid binding domain. Taken together, our results indicate that G0S2 also regulates human lipolysis by affecting enzyme activity and intracellular localization of ATGL. Increased lipolysis is known to contribute to the pathogenesis of insulin resistance, and G0S2 expression has been shown to be reduced in poorly controlled type 2 diabetic patients. Our data indicate that downregulation of G0S2 in adipose tissue could represent one of the underlying causes leading to increased lipolysis in the insulin-resistant state.

  20. Inhibition of Somatosensory Evoked Potentials During Different Modalities of Spinal Cord Stimulation: A Case Report.

    PubMed

    Buonocore, Michelangelo; Demartini, Laura

    2016-12-01

    Although the number of patients with chronic neuropathic pain treated by spinal cord stimulation (SCS) is continuously increasing, its analgesic mechanism remains to be elucidated. Previous studies have demonstrated that classical SCS (low stimulation frequency evoking paresthesia) inhibits the somatosensory evoked potentials (SEPs). We describe here the results of a series of SEPs recordings performed in a female patient with chronic pain, using four different types of SCS: the classical SCS (60 Hz, 250 μsec) and three paresthesia free SCS modalities: high frequency (10 kHz, 20 μsec) and two types of high-density SCS (500 Hz, 500 μsec and 200 Hz, 1000 μsec). All the tested SCS modalities completely inhibited the SEPs cortical responses, with an immediate recovery of the inhibition after turning the stimulator off. All the tested SCS modalities are able to inhibit SEPs and thus the lemniscal system. In particular, both paresthesia and paresthesia free SCS affect SEPs in the same manner. The presence of this inhibitory effect during paresthesia free modalities suggests that it is independent from the generation of action potentials, with a probable mechanism acting at the stimulation site. Further studies investigating the relationship between the inhibition of the lemniscal system and the analgesic effect of the SCS are, therefore, warranted. © 2016 International Neuromodulation Society.

  1. Dichloroacetate inhibits glycolysis and augments insulin-stimulated glycogen synthesis in rat muscle.

    PubMed Central

    Clark, A S; Mitch, W E; Goodman, M N; Fagan, J M; Goheer, M A; Curnow, R T

    1987-01-01

    The decrease in plasma lactate during dichloroacetate (DCA) treatment is attributed to stimulation of lactate oxidation. To determine whether DCA also inhibits lactate production, we measured glucose metabolism in muscles of fed and fasted rats incubated with DCA and insulin. DCA increased glucose-6-phosphate, an allosteric modifier of glycogen synthase, approximately 50% and increased muscle glycogen synthesis and glycogen content greater than 25%. Lactate release fell; inhibition of glycolysis accounted for greater than 80% of the decrease. This was associated with a decrease in intracellular AMP, but no change in citrate or ATP. When lactate oxidation was increased by raising extracellular lactate, glycolysis decreased (r = - 0.91), suggesting that lactate oxidation regulates glycolysis. When muscle lactate production was greatly stimulated by thermal injury, DCA increased glycogen synthesis, normalized glycogen content, and inhibited glycolysis, thereby reducing lactate release. The major effect of DCA on lactate metabolism in muscle is to inhibit glycolysis. PMID:3543056

  2. Higher Levels of ATGL Are Associated with Exercise-Induced Enhancement of Lipolysis in Rat Epididymal Adipocytes

    PubMed Central

    Ogasawara, Junetsu; Sakurai, Takuya; Kizaki, Takako; Ishibashi, Yoshinaga; Izawa, Tetsuya; Sumitani, Yoshikazu; Ishida, Hitoshi; Radak, Zsolt; Haga, Shukoh; Ohno, Hideki

    2012-01-01

    Background In adipose cells, adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte triacylglyceride hydrolysis, thereby regulating both basal and hormone-stimulated lipolysis. However, little is known about the molecular mechanism(s) underlying habitual exercise-induced adaptive modulation of ATGL in white adipocytes via alteration in transcription regulator and lipolytic cofactors. Methodology/Principal Results Male Wistar rats were randomly divided into 2 groups a sedentary control group (CG) and a habitual exercise group (EG). The EG was subjected to running on a treadmill set at 5 days per week for 9 weeks. The CG was not subjected to running on a treadmill. In the EG, levels of ATGL mRNA and protein were elevated with a significant increase in lipolysis compared with the CG, accompanied by a significant increase in associations of CGI-58 with ATGL protein. Under these conditions, an upregulation of peroxisome proliferation-activated receptorg-2 (PPARg-2) was observed. In the EG, the addition of rosiglitazone further significantly increased the levels of ATGL protein compared with the CG. However, attenuated levels of the ATGL protein in adipocytes were obtained by the addition of insulin, which is known to inhibit the expression of ATGL, in both types of groups. Actually, levels of plasma insulin were significantly reduced in the EG compared with the CG. Conclusions These data suggest that elevated levels of ATGL are involved in the exercise-induced enhancement of lipolysis in primary adipocytes. The exact mechanism(s) underlying this phenomenon is associated, at least in part, with upregulated transcriptional activation of PPARg-2. In addition, exercise-induced lower circulation levels of insulin also correlate with habitual exercise-induced higher levels of ATGL in primary adipocytes. PMID:22815850

  3. W-5 and quin 2-AM reverse the inhibitory effect of insulin on lipolysis due to dibutyryl cAMP.

    PubMed

    Goko, H; Matsuoka, A

    1999-05-01

    The effects of W-5, a weak calmodulin antagonist, and quin 2-AM, a cell permeant calcium chelator, on lipolysis and antilipolytic activity of insulin were studied in isolated rat adipocytes. We have previously shown that W-7, a strong calmodulin antagonist, suppresses the inhibitory effect of insulin on lipolysis due to dibutyryl cAMP (Bt2cAMP) in a dose-dependent manner [H. Goko, A. Matsuoka, Diabetes Res. Clin. Prac. 19 (1993) 177-181] and verapamil, a calcium antagonist, potentiates lipolysis due to Bt2cAMP. Like W-7, W-5 suppressed the antilipolytic action of insulin on lipolysis due to Bt2cAMP in a dose-dependent manner. However, when lipolysis was potentiated with 3-isobutyryl-1-methylxanthine (IBMX), W-5 did not suppress the antilipolytic action of insulin. At the same time, like verapamil, W-5 also potentiated lipolysis due to Bt2cAMP in a dose-dependent manner. Thus W-5 has the pharmaceutical effects of both W-7 and verapamil. The chelation of intracellular Ca2+ in adipocytes with quin 2-AM also produced a dose-dependent potentiation of lipolysis due to Bt2cAMP and suppression of the antilipolytic action of insulin on lipolysis due to Bt2cAMP. These effects of quin 2-AM are the same as those of W-5. Therefore, our results suggest that the cytoplasmic Ca2+ plays a pivotal role in mediating the potentiation of lipolysis and antilipolytic action of insulin when lipolysis is induced by Bt2cAMP in rat adipocytes and that W-5 appears to exert its pharmaceutical effects through the inhibition of intracellular calcium-dependent steps other than calmodulin.

  4. Inhibition of the baroreceptor reflex on stimulation in the brain stem defence centre

    PubMed Central

    Coote, J. H.; Hilton, S. M.; Perez-Gonzalez, J. F.

    1979-01-01

    1. In anaesthetized cats, the pattern of cardiovascular response characteristic of the defence reaction has been elicited by localized electrical stimulation within the appropriate region of the hypothalamus. The baroreceptor reflex response has been elicited by raising the pressure in a blind sac preparation of the carotid sinus or by electrical stimulation of the sinus nerve. 2. In addition to arterial blood pressure, heart rate and regional blood flows, activity was recorded in cardiac and renal sympathetic nerves, to assess more precisely the cardiomotor and vasomotor changes during interactions between brain stem stimulation and baroreceptor activation. 3. The sympatho-inhibitory and depressor effects of carotid sinus stimulation or electrical stimulation of the sinus nerve could be completely suppressed by stimulation within the hypothalamic defence area, as could the reflex bradycardia. It is concluded that this suppression is effected through the central nervous system. 4. Stimulation at points in the hypothalamus close to, but outside, the defence area, and which elicited increases in arterial pressure and sympathetic activity of similar magnitude to those from the defence area itself, did not abolish the sympatho-inhibitory or depressor effects of baroreceptor activation, though the reflex bradycardia was usually inhibited. It is suggested that this less localized change results from augmentation of the central inspiratory drive which inhibits the vagal outflow to the heart. ImagesFig. 1Fig. 3Fig. 4 PMID:572871

  5. TNF directly stimulates glucose uptake and leucine oxidation and inhibits FFA flux in conscious dogs.

    PubMed

    Sakurai, Y; Zhang, X J; Wolfe, R R

    1996-05-01

    We tested the hypothesis that the metabolic changes in glucose, lipid, and protein metabolism seen during tumor necrosis factor (TNF) infusion were due to the increase in plasma glucagon concentration rather than to the direct effects of TNF. We employed a pancreatic clamp technique to keep plasma insulin and glucagon concentrations constant throughout a 4-h isotope infusion. Glucose, lipid, and protein kinetics were measured by means of the primed, constant infusion of [6,6-2H]glucose, [2H5]glycerol, [2H2]palmitic acid, and [1-13C]leucine. After a 2-h baseline period (period 1), TNF was infused as a primed, constant infusion (prime, 2.5 micrograms/kg; constant infusion, 62.5 ng.kg-1.min-1) for 2 h (period 2). Whereas plasma glucose concentration dropped significantly during TNF infusion, endogenous glucose production did not change. The decrease in glucose concentrations was due to a stimulation of glucose clearance (P < 0.05). The rate of lipolysis did not decrease significantly, but free fatty acid (FFA) flux and plasma FFA concentration significantly decreased during TNF infusion (P < 0.05). The rate of appearance of leucine was not affected by TNF infusion, but TNF caused a significant increase in 13CO2 excretion (P < 0.05) and leucine oxidation (P < 0.05). The calculated rates of whole body protein synthesis decreased. We concluded that TNF did not directly affect glucose production. Furthermore, changes in protein and lipid kinetics during TNF infusion were not mediated by changes in insulin or glucagon and may have reflected direct effects of TNF.

  6. Germline ablation of VGF increases lipolysis in white adipose tissue.

    PubMed

    Fargali, Samira; Scherer, Thomas; Shin, Andrew C; Sadahiro, Masato; Buettner, Christoph; Salton, Stephen R

    2012-11-01

    Targeted deletion of VGF, a neuronal and endocrine secreted protein and neuropeptide precursor, produces a lean, hypermetabolic mouse that is resistant to diet-, lesion-, and genetically induced obesity and diabetes. We hypothesized that increased sympathetic nervous system activity in Vgf-/Vgf- knockout mice is responsible for increased energy expenditure and decreased fat storage and that increased β-adrenergic receptor stimulation induces lipolysis in white adipose tissue (WAT) of Vgf-/Vgf- mice. We found that fat mass was markedly reduced in Vgf-/Vgf- mice. Within knockout WAT, phosphorylation of protein kinase A substrate increased in males and females, phosphorylation of hormone-sensitive lipase (HSL) (ser563) increased in females, and levels of adipose triglyceride lipase, comparative gene identification-58, and phospho-perilipin were higher in male Vgf-/Vgf- WAT compared with wild-type, consistent with increased lipolysis. The phosphorylation of AMP-activated protein kinase (AMPK) (Thr172) and levels of the AMPK kinase, transforming growth factor β-activated kinase 1, were decreased. This was associated with a decrease in HSL ser565 phosphorylation, the site phosphorylated by AMPK, in both male and female Vgf-/Vgf- WAT. No significant differences in phosphorylation of CREB or the p42/44 MAPK were noted. Despite this evidence supporting increased cAMP signaling and lipolysis, lipogenesis as assessed by fatty acid synthase protein expression and phosphorylated acetyl-CoA carboxylase was not decreased. Our data suggest that the VGF precursor or selected VGF-derived peptides dampen sympathetic outflow pathway activity to WAT to regulate fat storage and lipolysis.

  7. Afferents contributing to autogenic inhibition of gastrocnemius following electrical stimulation of its tendon.

    PubMed

    Khan, Serajul I; Burne, John A

    2009-07-28

    Electrical stimulation of the Achilles tendon produced strong reflex inhibition of the ongoing voluntary EMG activity in the two heads of the gastrocnemius (GA) muscle in all tested subjects. The inhibition was seen clearly in both averaged and single sweep surface EMG records. The inhibitory response was produced without electrical (M wave) or mechanical, (muscle twitch) signs of direct muscle stimulation. The onset latency and duration for the first period of inhibition (I(1)) were 47-49 ms and 67 ms, respectively. A second inhibition (I(2)) had an onset latency of 187-193 ms and duration under 40 ms. Non-noxious stimuli in the range of 2.6-7.6 x mean perceptual threshold, when delivered to four locations over the GA tendon, all produced clear inhibition of the voluntary muscle activity. The inhibition was maximal when the cathode was a large metal plate located near the musculotendinous junction and decreased approximately linearly with distances more distal to that site. The effect of passive muscle stretch on the electrically induced tendon reflex inhibition (TRE) was tested at ankle joint angles incremented in steps of 20 degrees. It was found that TRE is strongly dependent on joint angle, being maximal in the fully stretched muscle. TRE was lost completely after partial tibial nerve block. In comparison, GA inhibition produced by cutaneous (sural) nerve stimulation was of a higher threshold, longer latency and persisted after partial tibial nerve block. We thus demonstrated a powerful autogenic inhibition in the lower limb arising from tendon afferents in conscious subjects that is increased by passive muscle stretch and likely to originate from group I tendon afferents.

  8. The contribution of classical (beta1/2-) and atypical beta-adrenoceptors to the stimulation of human white adipocyte lipolysis and right atrial appendage contraction by novel beta3-adrenoceptor agonists of differing selectivities.

    PubMed

    Sennitt, M V; Kaumann, A J; Molenaar, P; Beeley, L J; Young, P W; Kelly, J; Chapman, H; Henson, S M; Berge, J M; Dean, D K; Kotecha, N R; Morgan, H K; Rami, H K; Ward, R W; Thompson, M; Wilson, S; Smith, S A; Cawthorne, M A; Stock, M J; Arch, J R

    1998-06-01

    The role of beta3- and other putative atypical beta-adrenoceptors in human white adipocytes and right atrial appendage has been investigated using CGP 12177 and novel phenylethanolamine and aryloxypropanolamine beta3-adrenoceptor (beta3AR) agonists with varying intrinsic activities and selectivities for human cloned betaAR subtypes. The ability to demonstrate beta1/2AR antagonist-insensitive (beta3 or other atypical betaAR-mediated) responses to CGP 12177 was critically dependent on the albumin batch used to prepare and incubate the adipocytes. Four aryloxypropanolamine selective beta3AR agonists (SB-226552, SB-229432, SB-236923, SB-246982) consistently elicited beta1/2AR antagonist-insensitive lipolysis. However, a phenylethanolamine (SB-220646) that was a selective full beta3AR agonist elicited full lipolytic and inotropic responses that were sensitive to beta1/2AR antagonism, despite it having very low efficacies at cloned beta1- and beta2ARs. A component of the response to another phenylethanolamine selective beta3AR agonist (SB-215691) was insensitive to beta1/2AR antagonism in some experiments. Because no [corrected] novel aryloxypropanolamine had a beta1/2AR antagonist-insensitive inotropic effect, these results establish more firmly that beta3ARs mediate lipolysis in human white adipocytes, and suggest that putative 'beta4ARs' mediate inotropic responses to CGP 12177. The results also illustrate the difficulty of predicting from studies on cloned betaARs which betaARs will mediate responses to agonists in tissues that have a high number of beta1- and beta2ARs or a low number of beta3ARs.

  9. CD36 level and trafficking are determinants of lipolysis in adipocytes

    PubMed Central

    Zhou, Dequan; Samovski, Dmitri; Okunade, Adewole L.; Stahl, Philip D.; Abumrad, Nada A.; Su, Xiong

    2012-01-01

    CD36 has been linked to the etiology of insulin resistance and inflammation. We explored its function in regulating adipose tissue lipolysis, which influences fat accumulation by liver and muscle and overall metabolism. Knockdown of CD36 in differentiated 3T3-L1 adipocytes decreased lipolysis in response to 10 μM of the β-adrenergic agonist isoproterenol (by 42%), 10 μM of the adenyl cyclase activator forskolin (by 32%), and 500 μM of the phosphodiesterase (PDE) inhibitor isobutylmethylxanthine (by 33%). All three treatments in the knockdown adipocytes were associated with significant decreases of cAMP levels and of the hormone-sensitive lipase (HSL) and perilipin phosphorylation. An important role for PDE was supported by the lack of inhibition of the lipolysis induced by the poorly hydrolyzable dibutyryl cAMP analog. An additional contributory mechanism was diminished activation of the Src-ERK1/2 pathway. Regulation of lipolysis and lipolytic signaling by CD36 was reproduced with adipose tissue from CD36−/− mice. The importance of surface CD36 in this regulation was suggested by the finding that the plasma membrane-impermeable CD36 inhibitor sulfo-N-succinimidyl oleate (20 μM) decreased lipolysis. Interestingly, isoproterenol induced CD36 internalization, and this process was blocked by HSL inhibition, suggesting feedback regulation of adipocyte lipolysis via CD36 trafficking.—Zhou, D., Samovski, D., Okunade, A. L., Stahl, P. D., Abumrad, N. A., Su, X.. CD36 level and trafficking are determinants of lipolysis in adipocytes. PMID:22815385

  10. The G0/G1 Switch Gene 2 Regulates Adipose Lipolysis through Association with Adipose Triglyceride Lipase

    PubMed Central

    Yang, Xingyuan; Lu, Xin; Lombès, Marc; Rha, Geun Bae; Chi, Young-In; Guerin, Theresa M.; Smart, Eric J.; Liu, Jun

    2010-01-01

    Summary Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme for triacylglycerol (TAG) hydrolysis in adipocytes. The precise mechanisms whereby ATGL is regulated remain uncertain. Here we demonstrate that a protein encoded by G0/G1 switch gene 2 (G0S2) is a selective regulator of ATGL. G0S2 is highly expressed in adipose tissue and differentiated adipocytes. When overexpressed in HeLa cells, G0S2 localizes to lipid droplets and prevents their degradation mediated by ATGL. Moreover, G0S2 specifically interacts with ATGL, requiring the hydrophobic domain of G0S2 and the patatin-like domain of ATGL. More importantly, interaction with G0S2 inhibits the TAG hydrolase activity of ATGL. Furthermore, knockdown of endogenous G0S2 accelerates basal and stimulated lipolysis in adipocytes, while overexpression of G0S2 diminishes the rate of lipolysis in both adipocytes and adipose tissue explants. Thus, G0S2 functions to attenuate ATGL action both in vitro and in vivo, underlying a novel mechanism for the regulation of TAG hydrolysis. PMID:20197052

  11. AMPK Phosphorylates Desnutrin/ATGL and Hormone-Sensitive Lipase To Regulate Lipolysis and Fatty Acid Oxidation within Adipose Tissue

    PubMed Central

    Kim, Sun-Joong; Tang, Tianyi; Abbott, Marcia; Viscarra, Jose A.; Wang, Yuhui

    2016-01-01

    The role of AMP-activated protein kinase (AMPK) in promoting fatty acid (FA) oxidation in various tissues, such as liver and muscle, has been well understood. However, the role of AMPK in lipolysis and FA metabolism in adipose tissue has been controversial. To investigate the role of AMPK in the regulation of adipose lipolysis in vivo, we generated mice with adipose-tissue-specific knockout of both the α1 and α2 catalytic subunits of AMPK (AMPK-ASKO mice) by using aP2-Cre and adiponectin-Cre. Both models of AMPK-ASKO ablation show no changes in desnutrin/ATGL levels but have defective phosphorylation of desnutrin/ATGL at S406 to decrease its triacylglycerol (TAG) hydrolase activity, lowering basal lipolysis in adipose tissue. These mice also show defective phosphorylation of hormone-sensitive lipase (HSL) at S565, with higher phosphorylation at protein kinase A sites S563 and S660, increasing its hydrolase activity and isoproterenol-stimulated lipolysis. With higher overall adipose lipolysis, both models of AMPK-ASKO mice are lean, having smaller adipocytes with lower TAG and higher intracellular free-FA levels. Moreover, FAs from higher lipolysis activate peroxisome proliferator-activated receptor delta to induce FA oxidative genes and increase FA oxidation and energy expenditure. Overall, for the first time, we provide in vivo evidence of the role of AMPK in the phosphorylation and regulation of desnutrin/ATGL and HSL and thus adipose lipolysis. PMID:27185873

  12. Heterotopic CO2 laser stimulation inhibits tooth-related somatosensory evoked potentials.

    PubMed

    Fujii-Abe, Keiko; Oono, Yuka; Motohashi, Katsunori; Fukayama, Haruhisa; Umino, Masahiro

    2010-06-01

    The diffuse noxious inhibitory control (DNIC) effect is the neurophysiological basis for the phenomenon that heterotopic "pain inhibits pain" in remote areas of the body. The effect of DNIC is mediated by spino-bulbo-spinal loops and a final postsynaptic inhibitory mechanism. The DNIC effect depends on intensity, duration, quality, and application site of conditioning stimulation and stimulated nerve fiber-type. DNIC induced by CO(2) laser conditioning stimulation has, however, not yet been investigated, and the present study was designed to examine this. As the indicator of test stimulation, the late component of somatosensory evoked potentials (SEPs) induced by electrical tooth stimulation and pain intensity were examined under CO(2) laser conditioning stimulation. As the conditioning stimuli, CO(2) laser energy (lambda = 10.6 microm, spot size Ø = 2 mm) was applied to the dorsum of the left hand. The maximum reductions in SEP amplitude and pain intensity evaluated using a visual analog scale were 34.7% and 28.7%, respectively during CO(2) laser conditioning stimulation. No aftereffect was observed. The present study revealed that CO(2) laser radiation attenuated the late component of SEPs induced by electrical tooth stimulation, triggering the DNIC effect but with no aftereffect.

  13. Complete inhibition of food-stimulated gastric acid secretion by combined application of pirenzepine and ranitidine.

    PubMed Central

    Londong, W; Londong, V; Ruthe, C; Weizert, P

    1981-01-01

    In a double-blind, placebo controlled and randomised secretory study the effectiveness of pirenzepine, ranitidine, and their combination was compared intraindividually in eight healthy subjects receiving intravenous bolus injections. Pirenzepine (0.15 mg/kg) plus ranitidine (0.6 mg/kg) suppressed peptone-stimulated gastric acid secretion from 69 +/- 11 to 2 +/- 0.4 mmol H+/3 h; the mean percentage inhibition was 97%. Postprandial gastrin was unaffected. There were only minor side-effects in a few experiments (reduction of salivation, brief blurring of vision), but no prolactin stimulation after ranitidine or ranitidine plus pirenzepine. The combined application of ranitidine and pirenzepine inhibited meal-stimulated acid secretion more effectively and produced fewer side-effects than the combination of cimetidine plus pirenzepine studied previously. PMID:6114900

  14. Reflex inhibition of normal cramp following electrical stimulation of the muscle tendon.

    PubMed

    Khan, Serajul I; Burne, John A

    2007-09-01

    Muscle cramp was induced in one head of the gastrocnemius muscle (GA) in eight of thirteen subjects using maximum voluntary contraction when the muscle was in the shortened position. Cramp in GA was painful, involuntary, and localized. Induction of cramp was indicated by the presence of electromyographic (EMG) activity in one head of GA while the other head remained silent. In all cramping subjects, reflex inhibition of cramp electrical activity was observed following Achilles tendon electrical stimulation and they all reported subjective relief of cramp. Thus muscle cramp can be inhibited by stimulation of tendon afferents in the cramped muscle. When the inhibition of cramp-generated EMG and voluntary EMG was compared at similar mean EMG levels, the area and timing of the two phases of inhibition (I(1), I(2)) did not differ significantly. This strongly suggests that the same reflex pathway was the source of the inhibition in both cases. Thus the cramp-generated EMG is also likely to be driven by spinal synaptic input to the motorneurons. We have found that the muscle conditions that appear necessary to facilitate cramp, a near to maximal contraction of the shortened muscle, are also the conditions that render the inhibition generated by tendon afferents ineffective. When the strength of tendon inhibition in cramping subjects was compared with that in subjects that failed to cramp, it was found to be significantly weaker under the same experimental conditions. It is likely that reduced inhibitory feedback from tendon afferents has an important role in generating cramp.

  15. Adrenergic control of lipolysis in women compared with men

    PubMed Central

    Bessesen, Daniel H.; Stotz, Sarah; Peelor, Frederick F.; Miller, Benjamin F.; Horton, Tracy J.

    2014-01-01

    Data suggest women are more sensitive to the lipolytic action of epinephrine compared with men while maintaining similar glucoregulatory effects (Horton et al. J Appl Physiol 107: 200–210, 2009). This study aimed to determine the specific adrenergic receptor(s) that may mediate these sex differences. Lean women (n = 14) and men (n = 16) were studied on 4 nonconsecutive days during the following treatment infusions: saline (S: control), epinephrine [E: mixed β-adrenergic (lipolytic) and α2-adrenergic (antilipolytic) stimulation], epinephrine + phentolamine (E + P: mixed β-adrenergic stimulation only), and terbutaline (T: selective β2-adrenergic stimulation). Tracer infusions of glycerol, palmitate, and glucose were administered to determine systemic lipolysis, free fatty acid (FFA) release, and glucose turnover, respectively. Following basal measurements, substrate and hormone concentrations were measured in all subjects over 90 min of treatment and tracer infusion. Women had greater increases in glycerol and FFA concentrations with all three hormone infusions compared with men (P < 0.01). Glycerol and palmitate rate of appearance (Ra) and rate of disappearance (Rd) per kilogram body weight were greater with E infusion in women compared with men (P < 0.05), whereas no sex differences were observed with other treatments. Glucose concentration and kinetics were not different between sexes with any infusion. In conclusion, these data support the hypothesis that the greater rate of lipolysis in women with infusion of E was likely due to lesser α2 antilipolytic activation. These findings may help explain why women have greater lipolysis and fat oxidation during exercise, a time when epinephrine concentration is elevated. PMID:25190743

  16. Adrenergic control of lipolysis in women compared with men.

    PubMed

    Schmidt, Stacy L; Bessesen, Daniel H; Stotz, Sarah; Peelor, Frederick F; Miller, Benjamin F; Horton, Tracy J

    2014-11-01

    Data suggest women are more sensitive to the lipolytic action of epinephrine compared with men while maintaining similar glucoregulatory effects (Horton et al. J Appl Physiol 107: 200-210, 2009). This study aimed to determine the specific adrenergic receptor(s) that may mediate these sex differences. Lean women (n = 14) and men (n = 16) were studied on 4 nonconsecutive days during the following treatment infusions: saline (S: control), epinephrine [E: mixed β-adrenergic (lipolytic) and α2-adrenergic (antilipolytic) stimulation], epinephrine + phentolamine (E + P: mixed β-adrenergic stimulation only), and terbutaline (T: selective β2-adrenergic stimulation). Tracer infusions of glycerol, palmitate, and glucose were administered to determine systemic lipolysis, free fatty acid (FFA) release, and glucose turnover, respectively. Following basal measurements, substrate and hormone concentrations were measured in all subjects over 90 min of treatment and tracer infusion. Women had greater increases in glycerol and FFA concentrations with all three hormone infusions compared with men (P < 0.01). Glycerol and palmitate rate of appearance (Ra) and rate of disappearance (Rd) per kilogram body weight were greater with E infusion in women compared with men (P < 0.05), whereas no sex differences were observed with other treatments. Glucose concentration and kinetics were not different between sexes with any infusion. In conclusion, these data support the hypothesis that the greater rate of lipolysis in women with infusion of E was likely due to lesser α2 antilipolytic activation. These findings may help explain why women have greater lipolysis and fat oxidation during exercise, a time when epinephrine concentration is elevated.

  17. Insulin inhibits AMPA-induced neuronal damage via stimulation of protein kinase B (Akt).

    PubMed

    Kim, S-J; Han, Y

    2005-02-01

    We designed a series of experiments to explore the neuroprotective effects of insulin. Insulin significantly inhibited the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-induced neuronal cell damage as evidenced by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay. However, insulin had little affect on the AMPA-induced glial cell damage. To determine whether insulin inhibits AMPA-induced excitotoxicity, we performed grease-gap recording assays using rat brain slices. In these experiments, insulin also significantly inhibited AMPA-induced depolarization. Flow cytometry and DNA fragmentation assays showed that insulin inhibits AMPA-induced apoptosis and DNA fragmentation, respectively. Insulin stimulated protein kinase B (Akt) activity, whereas AMPA pretreatment did not alter the insulin-stimulated Akt activity. On the contrary, insulin blocked induction of SAPK/JNK, which AMPA stimulated. Taken together, these results suggest that insulin exerts neuroprotective effects by inhibiting AMPA-induced excitotoxicity and apoptosis, possibly by activating Akt and blocking SAPK/JNK.

  18. ARP101 inhibits α-MSH-stimulated melanogenesis by regulation of autophagy in melanocytes.

    PubMed

    Kim, Eun Sung; Jo, Yoon Kyung; Park, So Jung; Chang, Huikyoung; Shin, Ji Hyun; Choi, Eun Sun; Kim, Jun Bum; Seok, Su Hyeon; Kim, Jae-Sung; Oh, Jeong Su; Kim, Myoung-Hwan; Lee, Eunjoo H; Cho, Dong-Hyung

    2013-12-11

    Autophagy is a cooperative process between autophagosomes and lysosomes that degrades cellular organelles. Although autophagy regulates the turnover of cellular components, its role in melanogenesis is not clearly established. Previously, we reported that ARP101 induces autophagy in various cancer cells. Here, we show that ARP101 inhibits melanogenesis by regulation of autophagy. ARP101 inhibited α-MSH-stimulated melanin synthesis and suppressed the expression of tyrosinase and TRP1 in immortalized mouse melanocytes. ARP101 also induced autophagy in melanocytes. Knockdown of ATG5 reduced both anti-melanogenic activity and autophagy mediated by ARP101 in α-MSH treated melanocytes. Electron microscopy analysis further revealed that autophagosomes engulf melanin or melanosome in α-MSH and ARP101-treated cells. Collectively, our results suggest that ARP101 inhibits α-MSH-stimulated melanogenesis through the activation of autophagy in melanocytes.

  19. Spinal inhibition of phrenic motoneurones by stimulation of afferents from peripheral muscles.

    PubMed Central

    Eldridge, F L; Gill-Kumar, P; Millhorn, D E; Waldrop, T G

    1981-01-01

    1. Phrenic nerve responses to stimulation of calf muscle receptors or their afferents were studied in two groups of cats. One consisted of paralysed, vagotomized and functionally glomectomized animals with intact central nervous systems. The other included paralysed high (C1) spinal animals whose phrenic nerve activity was either spontaneously tonic or phasic, or evoked by activation of the intercostal-to-phrenic reflex. In both groups, end-tidal PCO2 was maintained at a constant level by means of a servo-controller. 2. Physical stimulation of calf muscles in animals with intact central respiratory controller and a generally facilitatory effect on frequency, with appropriate changes of both inspiratory and expiratory durations, and on peak magnitude of phrenic (neural tidal) activity. However, for the first few sec after onset of the stimulus, neural tidal activity was inhibited. 3. Physical stimulation of calf muscles or electrical stimulation of the tibial nerve in high spinal animals uniformly caused inhibition of spontaneous phrenic activity and that evoked by facilitatory conditioning stimuli. The degree of inhibition gradually decreased as muscle stimulation continued. Following offset of muscle stimulation, post-stimulus augmentation of phrenic activity occurred, with subsequent gradual return to control level over a period of 20-25 sec. 4. We conclude that stimulation of muscle afferents in the leg has a predominantly facilitatory respiratory effect when acting through brain stem controller mechanisms, but also has a purely inhibitory effect on phrenic motoneurones when acting via spinal mechanisms. 5. In addition, the findings are consistent with (1) progressive accommodation of phrenic motoneurones during continued inhibitory input, and (2) with a large and prolonged post-inhibitory rebound of excitability. PMID:7264986

  20. AMP-activated Protein Kinase Is Activated as a Consequence of Lipolysis in the Adipocyte

    USDA-ARS?s Scientific Manuscript database

    AMP-activated protein kinase (AMPK) is activated in adipocytes during exercise and other states in which lipolysis is stimulated. However, the mechanism(s) responsible for this effect and its physiological relevance are unclear. To examine these questions, 3T3-L1 adipocytes were treated with agents...

  1. Assessment of Homonymous Recurrent Inhibition during Voluntary Contraction by Conditioning Nerve Stimulation

    PubMed Central

    Duclay, Julien; Martin, Alain

    2016-01-01

    In humans, the amount of spinal homonymous recurrent inhibition during voluntary contraction is usually assessed by using a peripheral nerve stimulation paradigm. This method consists of conditioning the maximal M-wave (SM stimulus) with prior reflex stimulation (S1), with 10 ms inter-stimulus interval (ISI). The decrease observed between unconditioned (S1 only) and conditioned (S1+SM) reflex size is then attributed to recurrent inhibition. However, during a voluntary contraction, a superimposed SM stimulation leads to a maximal M-wave followed by a voluntary (V) wave at similar latency than the H-reflex. This wave can therefore interfere with the conditioned H-reflex when two different stimulation intensities are used (S1 and SM), leading to misinterpretation of the data. The aim of the present study was to assess if conditioning V-wave response instead of H-reflex, by applying SM for both stimuli (test and conditioning), can be used as an index of recurrent inhibition. Conditioned and unconditioned responses of soleus and medial gastrocnemius muscles were recorded in twelve subjects at 25% and at 50% of maximal voluntary contraction at the usual ISI of 10 ms and an optimal inter-stimulus of 15 ms determined upon M- and V-wave latencies. Conditioned H-reflex (obtained with S1+SM paradigm) was significantly lower than the unconditioned by ~30% on average, meaning that the amount of inhibition was 70%. This amount of recurrent inhibition was significantly lower at higher force level with both methods. Regardless of the level of force or the conditioning ISI, results obtained with V-wave conditioning (SM+SM) were similar at both force levels, linearly correlated and proportional to those obtained with H conditioning. Then, V-wave conditioning appears to be a reliable index of homonymous recurrent inhibition during voluntary contraction. PMID:27880831

  2. Minocycline hydrochloride nanoliposomes inhibit the production of TNF-α in LPS-stimulated macrophages

    PubMed Central

    Liu, D; Yang, P S

    2012-01-01

    Background As an adjunctive treatment of chronic periodontitis, it seems that the application of periocline or the other antimicrobials is effective against periodontopathogens. In this study, nanoliposomes were investigated as carriers of minocycline hydrochloride and the inhibition effects of minocycline hydrochloride nanoliposomes on the proliferation and lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-α (TNF-α) of macrophages were elucidated. Methods After stimulation with 10 μg/mL LPS, murine macrophages (ANA-1) were treated with 10, 20, 40, 50 and 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline for 6, 12, 24, 48 and 60 hours, respectively. A tetrazolium (MTT) assay was used to evaluate macrophages cell proliferation rate and the levels of TNF-α mRNA were measured by SYBR Green Real Time PCR. Results Ten to 70 μg/mL 2% minocycline hydrochloride nanoliposomes, minocycline hydrochloride solution, and periocline showed dose- and time-dependent inhibition of ANA-1 proliferation. Minocycline hydrochloride nanoliposomes showed dose- and ratio-dependent inhibition of LPS-stimulated TNF-α secretion of ANA-1. The inhibition effect of 10 μg/mL minocycline hydrochloride nanoliposomes was significantly better than that of two positive control groups, and equated to that of 60 or 70 μg/mL periocline. The expression of TNF-α mRNA in experimental group continued to reduce linearly with time. Conclusion All three preparations of minocycline hydrochloride showed dose- and time-dependent inhibition of proliferation of ANA-1. Minocycline hydrochloride nanoliposomes have stronger and longer inhibition effect on LPS-stimulated TNF-α secretion of macrophages cell than minocycline hydrochloride solution and periocline. PMID:22973098

  3. Sympathetic neuro-adipose connections mediate leptin-driven lipolysis.

    PubMed

    Zeng, Wenwen; Pirzgalska, Roksana M; Pereira, Mafalda M A; Kubasova, Nadiya; Barateiro, Andreia; Seixas, Elsa; Lu, Yi-Hsueh; Kozlova, Albina; Voss, Henning; Martins, Gabriel G; Friedman, Jeffrey M; Domingos, Ana I

    2015-09-24

    Leptin is a hormone produced by the adipose tissue that acts in the brain, stimulating white fat breakdown. We find that the lipolytic effect of leptin is mediated through the action of sympathetic nerve fibers that innervate the adipose tissue. Using intravital two-photon microscopy, we observe that sympathetic nerve fibers establish neuro-adipose junctions, directly "enveloping" adipocytes. Local optogenetic stimulation of sympathetic inputs induces a local lipolytic response and depletion of white adipose mass. Conversely, genetic ablation of sympathetic inputs onto fat pads blocks leptin-stimulated phosphorylation of hormone-sensitive lipase and consequent lipolysis, as do knockouts of dopamine β-hydroxylase, an enzyme required for catecholamine synthesis. Thus, neuro-adipose junctions are necessary and sufficient for the induction of lipolysis in white adipose tissue and are an efferent effector of leptin action. Direct activation of sympathetic inputs to adipose tissues may represent an alternative approach to induce fat loss, circumventing central leptin resistance. PAPERCLIP. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. The relief of microtherm inhibition for p-fluoronitrobenzene mineralization using electrical stimulation at low temperatures.

    PubMed

    Zhang, Xueqin; Feng, Huajun; Liang, Yuxiang; Zhao, Zhiqing; Long, Yuyang; Fang, Yuan; Wang, Meizhen; Yin, Jun; Shen, Dongsheng

    2015-05-01

    Low temperature aggravates biological treatment of refractory p-fluoronitrobenzene (p-FNB) because of microtherm inhibition of microbial activity. Considering the potential characterization of energy supply for microbial metabolism and spurring microbial activity by electrical stimulation, a bioelectrochemical system (BES) was established to provide sustaining electrical stimulation for p-FNB mineralization at a low temperature. Electrical stimulation facilitated p-FNB treatment and bioelectrochemical reaction rate constants for the removal and defluorination of p-FNB at 10 °C were 0.0931 and 0.0054 h(-1), which were higher than the sums of the rates found using a biological system and an electrocatalytic system by 62.8 and 64.8%, respectively. At a low temperature, microbial activity in terms of dehydrogenase and ATPase was found to be higher with electrical stimulation, being 121.1 and 100.1% more active than that in the biological system. Moreover, stronger antioxidant ability was observed in the BES, which implied a better cold-resistance and relief of microtherm inhibition by electrical stimulation. Bacterial diversity analysis revealed a significant evolution of microbial community by electrical stimulation, and Clostridia was uniquely enriched. One bacterial sequence close to Pseudomonas became uniquely predominant, which appeared to be crucial for excellent p-FNB treatment performance in the BES at a low temperature. Economic evaluation revealed that the energy required to mineralize an extra mole of p-FNB was found to be 247 times higher by heating the system than by application of electrical stimulation. These results indicated that application of electrical stimulation is extremely promising for treating refractory waste at low temperatures.

  5. Shrinking and development of lipid droplets in adipocytes during catecholamine-induced lipolysis.

    PubMed

    Nagayama, Masafumi; Shimizu, Kyoko; Taira, Toshio; Uchida, Tsutomu; Gohara, Kazutoshi

    2010-01-04

    Time-lapse observation of adipocytes during catecholamine-induced lipolysis clearly shows that shrinking of existing lipid droplets (LDs) occurs in some adipocytes and that small LDs are newly developed in almost all cells. Immunofluorescence imaging reveals that activation and localization of hormone-sensitive lipase (HSL) on the surface of LDs, which are required for conferring maximal lipolysis, are necessary for the shrinking of the LDs. However, not all adipocytes in which phosphorylated HSL is localized on LDs exhibit shrinking of LDs. The simultaneous shrinking and development of LDs yield apparent fragmentation and dispersion of LDs in adipocytes stimulated with catecholamine.

  6. Dopamine Regulation of Lateral Inhibition between Striatal Neurons Gates the Stimulant Actions of Cocaine.

    PubMed

    Dobbs, Lauren K; Kaplan, Alanna R; Lemos, Julia C; Matsui, Aya; Rubinstein, Marcelo; Alvarez, Veronica A

    2016-06-01

    Striatal medium spiny neurons (MSNs) form inhibitory synapses on neighboring striatal neurons through axon collaterals. The functional relevance of this lateral inhibition and its regulation by dopamine remains elusive. We show that synchronized stimulation of collateral transmission from multiple indirect-pathway MSNs (iMSNs) potently inhibits action potentials in direct-pathway MSNs (dMSNs) in the nucleus accumbens. Dopamine D2 receptors (D2Rs) suppress lateral inhibition from iMSNs to disinhibit dMSNs, which are known to facilitate locomotion. Surprisingly, D2R inhibition of synaptic transmission was larger at axon collaterals from iMSNs than their projections to the ventral pallidum. Targeted deletion of D2Rs from iMSNs impaired cocaine's ability to suppress lateral inhibition and increase locomotion. These impairments were rescued by chemogenetic activation of Gi-signaling in iMSNs. These findings shed light on the functional significance of lateral inhibition between MSNs and offer a novel synaptic mechanism by which dopamine gates locomotion and cocaine exerts its canonical stimulant response. VIDEO ABSTRACT.

  7. Stimulation of h efflux and inhibition of photosynthesis by esters of carboxylic acids.

    PubMed

    Duhaime, D E; Bown, A W

    1983-11-01

    Suspensions of mechanically isolated Asparagus sprengeri Regel mesophyll cells were used to investigate the influence of various carboxyester compounds on rates of net H(+) efflux in the dark or light and photosynthetic O(2) production. Addition of 0.15 to 1.5 millimolar malathion, alpha-naphthyl acetate, phenyl acetate, or p-nitrophenyl acetate stimulated H(+) efflux and inhibited photosynthesis within 1 minute. In contrast, the more polar esters methyl acetoacetate or ethyl p-aminobenzoate had little or no effect on either of these two processes. A 0.15 millimolar concentration of alpha-naphthylacetate stimulated the normal rate of H(+) efflux, 0.77 nanomoles H(+) per 10(6) cells per minute by 750% and inhibited photosynthesis by 100%. The four active carboxyester compounds also stimulated H(+) efflux after the normal rate of H(+) efflux was eliminated with 0.01 milligrams per milliliter oligomycin or 100% N(2). Oligomycin reduced the ATP level by 70%. Incubation of cells with malathion, alpha-naphthyl acetate, or p-nitrophenyl acetate resulted in the generation of the respective hydrolysis products ethanol, alpha-naphthol, and p-nitrophenol. It is proposed that inhibition of photosynthesis and stimulation of H(+) efflux result when nonpolar carboxyester compounds enter the cell and generate acidic carboxyl groups when hydrolyzed by esterase enzymes.

  8. Reinforcement and stimulant medication ameliorate deficient response inhibition in children with Attention-Deficit/Hyperactivity Disorder

    PubMed Central

    Rosch, Keri S.; Fosco, Whitney D.; Pelham, William E.; Waxmonsky, James G.; Bubnik, Michelle G.; Hawk, Larry W.

    2015-01-01

    This study examined the degree to which reinforcement, stimulant medication, and their combination impact response inhibition in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Across three studies, participants with ADHD (n=111, 25 girls) and typically-developing (TD) controls (n=33, 6 girls) completed a standard version of the stop signal task (SST) and/or a reinforcement-manipulation SST with performance-contingent points. In two of these studies, these tasks were performed under placebo or 0.3 and 0.6 mg/kg methylphenidate (MPH) conditions. Cross-study comparisons were conducted to test hypotheses regarding the separate and combined effects of reinforcement and methylphenidate on response inhibition among children with ADHD relative to TD controls. Baseline response inhibition was worse among children with ADHD compared to controls. MPH produced dose-related improvements in response inhibition in children with ADHD; compared to non-medicated TD controls, 0.3 mg/kg MPH normalized deficient response inhibition, and 0.6 mg/kg MPH resulted in better inhibition in children with ADHD. Reinforcement improved response inhibition to a greater extent for children with ADHD than for TD children, normalizing response inhibition. The combination of MPH and reinforcement improved response inhibition among children with ADHD compared to reinforcement alone and MPH alone, also resulting in normalization of response inhibition despite repeated task exposure. Deficient response inhibition commonly observed in children with ADHD is significantly improved with MPH and/or reinforcement, normalizing inhibition relative to TD children tested under standard conditions. PMID:25985978

  9. Reinforcement and Stimulant Medication Ameliorate Deficient Response Inhibition in Children with Attention-Deficit/Hyperactivity Disorder.

    PubMed

    Rosch, Keri S; Fosco, Whitney D; Pelham, William E; Waxmonsky, James G; Bubnik, Michelle G; Hawk, Larry W

    2016-02-01

    This study examined the degree to which reinforcement, stimulant medication, and their combination impact response inhibition in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Across three studies, participants with ADHD (n = 111, 25 girls) and typically-developing (TD) controls (n = 33, 6 girls) completed a standard version of the stop signal task (SST) and/or a reinforcement-manipulation SST with performance-contingent points. In two of these studies, these tasks were performed under placebo or 0.3 and 0.6 mg/kg methylphenidate (MPH) conditions. Cross-study comparisons were conducted to test hypotheses regarding the separate and combined effects of reinforcement and methylphenidate on response inhibition among children with ADHD relative to TD controls. Baseline response inhibition was worse among children with ADHD compared to controls. MPH produced dose-related improvements in response inhibition in children with ADHD; compared to non-medicated TD controls, 0.3 mg/kg MPH normalized deficient response inhibition, and 0.6 mg/kg MPH resulted in better inhibition in children with ADHD. Reinforcement improved response inhibition to a greater extent for children with ADHD than for TD children, normalizing response inhibition. The combination of MPH and reinforcement improved response inhibition among children with ADHD compared to reinforcement alone and MPH alone, also resulting in normalization of response inhibition despite repeated task exposure. Deficient response inhibition commonly observed in children with ADHD is significantly improved with MPH and/or reinforcement, normalizing inhibition relative to TD children tested under standard conditions.

  10. Peroxisome proliferator-activated receptor gamma activation inhibits progesterone-stimulated human MUC1 expression.

    PubMed

    Wang, Peng; Dharmaraj, Neeraja; Brayman, Melissa J; Carson, Daniel D

    2010-07-01

    Mucin 1 (MUC1) is a type I transmembrane glycoprotein abundantly expressed on nearly all epithelial tissues and overexpressed by many cancer cells. Previous studies from our lab showed that progesterone receptor (PR)B is a strong stimulator of MUC1 gene expression. It is reported that liganded peroxisome proliferator-activated receptor gamma (PPARgamma) stimulates Muc1 expression in murine trophoblast. Here, we demonstrate that although the PPARgamma ligand, rosiglitazone, stimulates the murine Muc1 promoter in HEC1A, a human uterine epithelial cell line, rosiglitazone alone, has no significant effect on basal human MUC1 promoter activity. In fact, rosiglitazone treatment antagonizes progesterone-stimulated human MUC1 promoter activity and protein expression in two human uterine epithelial cell lines and T47D human breast cancer cells. This response is antagonized by the PPARgamma antagonist, GW9662, as well as a dominant-negative form of PPARgamma, demonstrating the response is mediated by PPARgamma. Additional studies indicate that PPARgamma activation does not change PR binding to the MUC1 promoter but generally antagonizes progesterone activity by stimulating PRB degradation and inhibiting progesterone-induced PRB phosphorylation. Collectively, these studies indicate that PPARgamma activation inhibits PRB activity through both acute (phosphorylation) and long-term (PRB degradation) pathways.

  11. The lipolysis/esterification cycle of hepatic triacylglycerol. Its role in the secretion of very-low-density lipoprotein and its response to hormones and sulphonylureas.

    PubMed Central

    Wiggins, D; Gibbons, G F

    1992-01-01

    In hepatocyte cultures maintained in the absence of extracellular fatty acids, at least 70% of the secreted very-low-density lipoprotein (VLDL) triacylglycerol was derived via lipolysis of intracellular triacylglycerol. This proportion was unchanged when the cells were exposed for 24 h to insulin or glucagon, hormones which decreased the overall secretion of intracellular triacylglycerol, or to chloroquine or tolbutamide, agents which inhibit lysosomal lipolysis. The rate of intracellular lipolysis was 2-3-fold greater than that required to maintain the observed rate of triacylglycerol secretion. Most of the fatty acids released were returned to the intracellular pool. Neither insulin nor glucagon had any significant effect on the overall lipolysis and re-esterification of intracellular triacylglycerol. In these cases a greater proportion of the released fatty acids re-entered the cellular pool, rather than being recruited for VLDL assembly. Tolbutamide inhibited intracellular lipolysis, but suppressed VLDL secretion to a greater extent. 3,5-Dimethylpyrazole did not affect lipolysis or VLDL secretion. The increased secretion of VLDL triacylglycerol observed after exposure of cells to insulin for 3 days was not accompanied by an increased rate of intracellular lipolysis. However, a larger proportion of the triacylglycerol secreted under these conditions may not have undergone prior lipolysis. PMID:1599431

  12. Amoxapine inhibition of GABA-stimulated chloride conductance: Investigations of potential sites of activity

    SciTech Connect

    Ikeda, M.; Knapp, R.J.; Yamamura, H.I. ); Malatynska, E. )

    1989-01-01

    Amoxapine inhibits GABA-stimulated chloride conductance by acting on the GABA{sub A}-receptor chloride-ionophore complex which can be studied using membrane vesicles prepared from rat cerebral cortex. Amoxapine produces a right shift in the GABA concentration-response curve for the stimulation of {sup 36}Cl{sup {minus}} uptake into these vesicles with no apparent change in the maximum response. Schild analysis of these data gave a pA{sub 2} value of 5.52 with a slope of 0.79. Amoxapine inhibits the binding of the GABA{sub A} receptor selective antagonist ({sup 3}H)SR 95531 with an IC{sub 50} value of 3.45 {mu}M and a pseudo Hill coefficient of 0.83. In contrast, 10 {mu}M amoxapine inhibits ({sup 3}H) flunitrazepam binding by less than 25% while the benzodiazepine antagonist Ro 15-1788 reduces the amoxapine inhibition of GABA-stimulated chloride conductance only at high concentrations.

  13. Inhibition of classically conditioned eyeblink responses by stimulation of the cerebellar cortex in the decerebrate cat.

    PubMed

    Hesslow, G

    1994-04-15

    The purpose of the present study was to test the hypothesis that neurones in the anterior interpositus nucleus, under the control of Purkinje cells in the c1 and c3 zones of the cerebellar cortex, exert some control over classically conditioned responses. In particular, the experiments were designed to determine whether the cerebellar control of conditioned and unconditioned responses is different. The experiments were performed on cats decerebrated rostral to the red nucleus under halothane anaesthesia. The cats were conditioned using either a 1000 Hz tone or trains of stimuli through the skin of the proximal forelimb as the conditioned stimulus, and periorbital electrical stimulation as the unconditioned stimulus. A large proportion of the animals acquired conditioned responses at normal rates. It could be shown that these were true conditioned responses and did not result from sensitization or pseudoconditioning. For instance, unpaired presentations of conditioned and unconditioned stimuli caused rapid extinction. Cerebellar areas controlling eyeblink were identified by recording climbing fibre responses in the cerebellar cortex and recording EMG activity in the eyelid evoked by stimulation of the cerebellar cortex. When single shocks of 40-70 microA were applied to these areas during the emission of conditioned eyeblink responses, the latter were strongly inhibited. The inhibition had a latency of about 10 ms and a duration of 25-75 ms. It was shown that this inhibition of the conditioned responses was topographically specific and could only be evoked from cortical sites identified as controlling eyeblink. Stimulation of the periphery of an eyeblink area caused little or no inhibition. The effect of cortical stimulation on unconditioned reflex responses in the orbicularis oculi muscle was also tested. Some inhibition of unconditioned responses was observed, but quantitative analysis showed that this inhibition was considerably weaker than the corresponding

  14. Inhibition of classically conditioned eyeblink responses by stimulation of the cerebellar cortex in the decerebrate cat.

    PubMed Central

    Hesslow, G

    1994-01-01

    The purpose of the present study was to test the hypothesis that neurones in the anterior interpositus nucleus, under the control of Purkinje cells in the c1 and c3 zones of the cerebellar cortex, exert some control over classically conditioned responses. In particular, the experiments were designed to determine whether the cerebellar control of conditioned and unconditioned responses is different. The experiments were performed on cats decerebrated rostral to the red nucleus under halothane anaesthesia. The cats were conditioned using either a 1000 Hz tone or trains of stimuli through the skin of the proximal forelimb as the conditioned stimulus, and periorbital electrical stimulation as the unconditioned stimulus. A large proportion of the animals acquired conditioned responses at normal rates. It could be shown that these were true conditioned responses and did not result from sensitization or pseudoconditioning. For instance, unpaired presentations of conditioned and unconditioned stimuli caused rapid extinction. Cerebellar areas controlling eyeblink were identified by recording climbing fibre responses in the cerebellar cortex and recording EMG activity in the eyelid evoked by stimulation of the cerebellar cortex. When single shocks of 40-70 microA were applied to these areas during the emission of conditioned eyeblink responses, the latter were strongly inhibited. The inhibition had a latency of about 10 ms and a duration of 25-75 ms. It was shown that this inhibition of the conditioned responses was topographically specific and could only be evoked from cortical sites identified as controlling eyeblink. Stimulation of the periphery of an eyeblink area caused little or no inhibition. The effect of cortical stimulation on unconditioned reflex responses in the orbicularis oculi muscle was also tested. Some inhibition of unconditioned responses was observed, but quantitative analysis showed that this inhibition was considerably weaker than the corresponding

  15. Fat in flames: influence of cytokines and pattern recognition receptors on adipocyte lipolysis.

    PubMed

    Grant, Ryan W; Stephens, Jacqueline M

    2015-08-01

    Adipose tissue has the largest capacity to store energy in the body and provides energy through the release of free fatty acids during times of energy need. Different types of immune cells are recruited to adipose tissue under various physiological conditions, indicating that these cells contribute to the regulation of adipose tissue. One major pathway influenced by a number of immune cells is the release of free fatty acids through lipolysis during both physiological (e.g., cold stress) and pathophysiological processes (e.g., obesity, type 2 diabetes). Adipose tissue expansion during obesity leads to immune cell infiltration and adipose tissue remodeling, a homeostatic process that promotes inflammation in adipose tissue. The release of proinflammatory cytokines stimulates lipolysis and causes insulin resistance, leading to adipose tissue dysfunction and systemic disruptions of metabolism. This review focuses on the interactions of cytokines and other inflammatory molecules that regulate adipose tissue lipolysis during physiological and pathophysiological states. Copyright © 2015 the American Physiological Society.

  16. Small-molecule compounds that modulate lipolysis in adipose tissue: targeting strategies and molecular classes.

    PubMed

    Wang, Minghan; Fotsch, Christopher

    2006-10-01

    Lipolysis is an important pathway in maintaining energy homeostasis through the degradation of triglycerides in adipose tissue and the release of fatty acids into the circulation as an energy source. However, an elevated level of circulating fatty acids leads to unfavorable metabolic effects such as insulin resistance and dyslipidemia. Cell surface receptors and intracellular components of the lipolytic pathway have been targeted to develop antilipolytic agents, among which are G-protein-coupled receptor agonists and lipase inhibitors. In addition, molecules that stimulate lipolysis have been tested in clinical trials as a treatment for obesity. Together, these molecules represent a diverse group of regulators for this pathway. This review will discuss strategies to target lipolysis and the major issues with representative small-molecule modulators of this pathway.

  17. Stimulation of beta-adrenoceptors inhibits calcium-dependent potassium-channels in mouse macrophages

    SciTech Connect

    Rosati, C.; Hannaert, P.; Dausse, J.P.; Braquet, P.; Garay, R.

    1986-12-01

    K/sup +/ efflux in mouse macrophages exhibited a rate constant (k/sub k/) of 0.67 +/- 0.04 (h)/sup -1/. This was strongly stimulated by increasing concentrations of the Ca/sup 2 +/ ionophore A23187 up to a maximal value of 4.01 +/- 0.25 (h)/sup -1/ with an IC/sub 50/ of 7.6 +/- 1.9 ..mu..M. Similar results were obtained with the Ca/sup 2 +/ ionophore ionomycin. Binding experiments with /sup 3/H-dihydroalprenolol revealed a high density of beta-adrenergic receptors with apparent dissociation constant of 2.03 +/- 0.06 nM. Isoproterenol at a concentration of 10/sup -6/ -10/sup -5/ M induced a two- to threefold stimulation of endogenous levels of cyclic AMP (cAMP). A23187-stimulated K/sup +/ efflux was partially inhibited by (i) stimulation of adenylate cyclase with isoproterenol, forskolin or, PGE/sub 1/; (ii) exogenous cAMP; and (iii) inhibition of phosphodiesterase with MIX (1-methyl-3-isobutylxanthine). Maximal inhibition of K/sup +/ efflux was obtained by simultaneous addition of isoproterenol and MIX. In dose-response curves, the isoproterenol-sensitive K/sup +/ efflux was half-maximally inhibited (IC/sub 50/) with 2-5 x 10/sup -10/ M of isoproterenol concentration. Propranolol was able to completely block the effect of isoproterenol, with an IC/sub 50/ of about 1-2 x 10/sup -7/ M. Isoproterenol and MIX did not inhibit A23187-stimulated K/sup +/ efflux in an incubation medium where NaCl was replaced by sucrose (or choline), suggesting the involvement of an Na/sup +/:Ca/sup 2 +/ exchange mechanism. The results show that stimulation of beta-adrenoceptors in mouse macrophages counter balances the opening of K/sup +/ channels induced by the calcium ionophore A23187. This likely reflects a decrease in cytoslic free calcium content via a cAMP-mediated stimulation of Na/sup +/:Ca/sup 2 +/ exchange.

  18. Dissecting adipose tissue lipolysis: molecular regulation and implications for metabolic disease.

    PubMed

    Nielsen, Thomas Svava; Jessen, Niels; Jørgensen, Jens Otto L; Møller, Niels; Lund, Sten

    2014-06-01

    Lipolysis is the process by which triglycerides (TGs) are hydrolyzed to free fatty acids (FFAs) and glycerol. In adipocytes, this is achieved by sequential action of adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase. The activity in the lipolytic pathway is tightly regulated by hormonal and nutritional factors. Under conditions of negative energy balance such as fasting and exercise, stimulation of lipolysis results in a profound increase in FFA release from adipose tissue (AT). This response is crucial in order to provide the organism with a sufficient supply of substrate for oxidative metabolism. However, failure to efficiently suppress lipolysis when FFA demands are low can have serious metabolic consequences and is believed to be a key mechanism in the development of type 2 diabetes in obesity. As the discovery of ATGL in 2004, substantial progress has been made in the delineation of the remarkable complexity of the regulatory network controlling adipocyte lipolysis. Notably, regulatory mechanisms have been identified on multiple levels of the lipolytic pathway, including gene transcription and translation, post-translational modifications, intracellular localization, protein-protein interactions, and protein stability/degradation. Here, we provide an overview of the recent advances in the field of AT lipolysis with particular focus on the molecular regulation of the two main lipases, ATGL and HSL, and the intracellular and extracellular signals affecting their activity.

  19. Stimulation and inhibition of adenylyl cyclase by distinct 5-hydroxytryptamine receptors.

    PubMed

    De Vivo, M; Maayani, S

    1990-10-01

    5-Hydroxytryptamine (serotonin, 5-HT) stimulates basal adenylyl cyclase activity in membranes from guinea pig or rat hippocampi, but 5-HT inhibits forskolin-stimulated adenylyl cyclase activity in these same membranes. The opposing effects of 5-HT on adenylyl cyclase activity indicate that distinct 5-HT receptors, positively and negatively coupled to adenylyl cyclase, are present in these membranes. Stimulation of adenylyl cyclase activity is mediated by two distinct 5-HT receptors. The receptor with lower affinity for 5-HT, designated as RL, is apparently homologous with a 5-HT receptor present in rat collicular membranes, but it is not homologous with the stimulatory receptor characterized in neuroblastoma hybrid cell (NCB-20) membranes. The receptor with higher affinity for 5-HT is homologous with the 5-HT1A binding site. The magnitude of stimulation by 5-HT1A receptors is variable with respect to stimulation by RL and is sometimes completely absent. Inhibition of forskolin-stimulated adenylyl cyclase activity, in membranes from either rat or guinea pig hippocampus or rat cortex, is a functional correlate of the 5-HT1A binding site. This inhibitory response was used to determine the pharmacological characteristics of drugs that reportedly have high affinity for 5-HT1A binding sites, such as 1-[2-(4-aminophenyl)ethyl]-4-(3-trifluoromethylphenyl)piperazine (PAPP) and (-)pindolol. PAPP inhibited adenylyl cyclase activity in guinea pig hippocampal membranes with an EC50 value of 27 +/- 3 nM. (-)Pindolol was a partial agonist in inhibiting adenylyl cyclase activity in guinea pig and rat hippocampal membranes. Because of the low intrinsic activity of (-)pindolol, it was tested as an antagonist of the inhibition produced by 5-HT1A receptor agonists in rat hippocampal membranes. The Kb of (-)pindolol was 40 nM as measured by a Schild plot. (-)Propranolol was a simple competitive antagonist at the rat hippocampal receptor with a Kb value of 550 nM. In summary, guinea pig

  20. Cortical Inhibition, Excitation, and Connectivity in Schizophrenia: A Review of Insights From Transcranial Magnetic Stimulation

    PubMed Central

    Rogasch, Nigel C.

    2014-01-01

    Schizophrenia (SCZ) is a debilitating mental illness with an elusive pathophysiology. Over the last decade, theories emphasizing cortical dysfunction have received increasing attention to explain the heterogeneous symptoms experienced in SCZ. Transcranial magnetic stimulation (TMS) is a noninvasive form of brain stimulation that is particularly suited to probing the fidelity of specific excitatory and inhibitory neuronal populations in conscious humans. In this study, we review the contribution of TMS in assessing inhibitory and excitatory neuronal populations and their long-range connections in SCZ. In addition, we discuss insights from combined TMS and electroencephalography into the functional consequences of impaired excitation/inhibition on cortical oscillations in SCZ. PMID:23722199

  1. Infrared neural stimulation (INS) inhibits electrically evoked neural responses in the deaf white cat

    NASA Astrophysics Data System (ADS)

    Richter, Claus-Peter; Rajguru, Suhrud M.; Robinson, Alan; Young, Hunter K.

    2014-03-01

    Infrared neural stimulation (INS) has been used in the past to evoke neural activity from hearing and partially deaf animals. All the responses were excitatory. In Aplysia californica, Duke and coworkers demonstrated that INS also inhibits neural responses [1], which similar observations were made in the vestibular system [2, 3]. In deaf white cats that have cochleae with largely reduced spiral ganglion neuron counts and a significant degeneration of the organ of Corti, no cochlear compound action potentials could be observed during INS alone. However, the combined electrical and optical stimulation demonstrated inhibitory responses during irradiation with infrared light.

  2. Cortical inhibition in first-degree relatives of schizophrenic patients assessed with transcranial magnetic stimulation.

    PubMed

    Saka, Meram Can; Atbasoglu, E Cem; Ozgüven, Halise Devrimci; Sener, H Ozden; Ozay, Ebru

    2005-12-01

    Although cortical inhibition deficit has been shown in schizophrenia patients by transcranial magnetic stimulation (TMS), some controversies remain, possibly due to confounding factors such as medication use and clinical state at the time of assessment. First-degree relatives of schizophrenia patients, who share various degrees of genetic vulnerability with the patients, but are free from confounds related to medication and/or florid psychosis, have not been studied to date. We compared 12 relatives with 14 controls on several paradigms with TMS. Three of the 12 healthy relatives lacked transcallosal inhibition (TI) in one or more of the stimulation levels. There were no significant differences in other parameters. The lack of TI in 25% of the relatives is an important finding that needs to be replicated in larger samples that are heterogeneous in terms of psychosis-proneness.

  3. FNDC5 overexpression and irisin ameliorate glucose/lipid metabolic derangements and enhance lipolysis in obesity.

    PubMed

    Xiong, Xiao-Qing; Chen, Dan; Sun, Hai-Jian; Ding, Lei; Wang, Jue-Jin; Chen, Qi; Li, Yue-Hua; Zhou, Ye-Bo; Han, Ying; Zhang, Feng; Gao, Xing-Ya; Kang, Yu-Ming; Zhu, Guo-Qing

    2015-09-01

    Irisin is a cleaved and secreted fragment of fibronectin type III domain containing 5 (FNDC5), and contributes to the beneficial effects of exercise on metabolism. Here we report the therapeutical effects of FNDC5/irisin on metabolic derangements and insulin resistance in obesity, and show the lipolysis effect of irisin and its signal molecular mechanism. In obese mice, lentivirus mediated-FNDC5 overexpression enhanced energy expenditure, lipolysis and insulin sensitivity, and reduced hyperlipidemia, hyperglycemia, hyperinsulinism, blood pressure and norepinephrine levels; it increased hormone-sensitive lipase (HSL) expression and phosphorylation, and reduced perilipin level and adipocyte diameter in adipose tissues. Subcutaneous perfusion of irisin reduced hyperlipidemia and hyperglycemia, and improved insulin resistance. Either FNDC5 overexpression or irisin perfusion only induced a tendency toward a slight decrease in body weight in obese mice. In 3T3-L1 adipocytes, irisin enhanced basal lipolysis rather than isoproterenol-induced lipolysis, which were prevented by inhibition of adenylate cyclase or PKA; irisin increased the HSL and perilipin phosphorylation; it increased PKA activity, and cAMP and HSL mRNA levels, but reduced perilipin expression. These results indicate that FNDC5/irisin ameliorates glucose/lipid metabolic derangements and insulin resistance in obese mice, and enhances lipolysis via cAMP-PKA-HSL/perilipin pathway. FNDC5 or irisin can be taken as an effective therapeutic strategy for metabolic disorders.

  4. 11β-Hydroxysteroid dehydrogenase type 1 shRNA ameliorates glucocorticoid-induced insulin resistance and lipolysis in mouse abdominal adipose tissue.

    PubMed

    Wang, Ying; Yan, Chaoying; Liu, Limei; Wang, Wei; Du, Hanze; Fan, Winnie; Lutfy, Kabirullah; Jiang, Meisheng; Friedman, Theodore C; Liu, Yanjun

    2015-01-01

    Long-term glucocorticoid exposure increases the risk for developing type 2 diabetes. Prereceptor activation of glucocorticoid availability in target tissue by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6PDH) is an important mediator of the metabolic syndrome. We explored whether the tissue-specific modulation of 11β-HSD1 and H6PDH in adipose tissue mediates glucocorticoid-induced insulin resistance and lipolysis and analyzed the effects of 11β-HSD1 inhibition on the key lipid metabolism genes and insulin-signaling cascade. We observed that corticosterone (CORT) treatment increased expression of 11β-HSD1 and H6PDH and induced lipase HSL and ATGL with suppression of p-Thr(172) AMPK in adipose tissue of C57BL/6J mice. In contrast, CORT induced adipose insulin resistance, as reflected by a marked decrease in IR and IRS-1 gene expression with a reduction in p-Thr(308) Akt/PKB. Furthermore, 11β-HSD1 shRNA attenuated CORT-induced 11β-HSD1 and lipase expression and improved insulin sensitivity with a concomitant stimulation of pThr(308) Akt/PKB and p-Thr(172) AMPK within adipose tissue. Addition of CORT to 3T3-L1 adipocytes enhanced 11β-HSD1 and H6PDH and impaired p-Thr(308) Akt/PKB, leading to lipolysis. Knockdown of 11β-HSD1 by shRNA attenuated CORT-induced lipolysis and reversed CORT-mediated inhibition of pThr(172) AMPK, which was accompanied by a parallel improvement of insulin signaling response in these cells. These findings suggest that elevated adipose 11β-HSD1 expression may contribute to glucocorticoid-induced insulin resistance and adipolysis. Copyright © 2015 the American Physiological Society.

  5. Melanocyte stimulating hormone peptides inhibit TNF-alpha signaling in human dermal fibroblast cells.

    PubMed

    Hill, R P; MacNeil, S; Haycock, J W

    2006-02-01

    Alpha-melanocyte stimulating hormone (alpha-MSH) has been identified as a potent anti-inflammatory in various tissues including the skin. It has previously been shown in skin cell keratinocytes and melanocytes/melanoma cells that MSH peptides inhibit TNF-alpha stimulated NF-kappaB activity and intercellular adhesion molecule-1 (ICAM-1) upregulation. However, the precise anti-inflammatory role of MSH peptides in dermal fibroblasts is unclear. Some studies report on pro-inflammatory responses, while others on anti-inflammatory responses. The present study confirms MC1R expression in cultured human dermal fibroblasts and reports that the MSH peptides alpha-MSH and KP(-D-)V inhibit TNF-alpha stimulated NF-kappaB activity and ICAM-1 upregulation, consistent with an anti-inflammatory role. However, involvement of IkappaB-alpha regulation by either peptide was not confirmed, supporting a mechanism independent of the NF-kappaB inhibitor. In conclusion, alpha-MSH and KP(-D-)V peptides have an anti-inflammatory action on dermal fibroblast signaling by inhibiting the pro-inflammatory activity of TNF-alpha in vitro.

  6. Inhibition of antibody formation during continual stimulation with a strong immunogen

    PubMed Central

    Gras, J.; Roca, Mercedes; Ayats, Rosa; Castro, Rosa; Duran, F.

    1974-01-01

    Long persisting antigenic stimulation at immunogenic levels leads to a profound inhibition of antibody formation. With Brucellus abortus, there is first a brief and high IgM response. IgG antibody titres remain at a low level for some days, and then begin a slow and progressive increase, leading to a rather persistent maximum, and finally after about 300 days, to the state of inhibition. When the same total dose is given with monthly intervals, the effect is quite different, with similar IgM and IgG peaks being observed after each dose. The inhibited animals respond moderately to a ten-fold higher antigen dose, and only with IgG. Six months after interruption of the persistent antigenic stimulus, a strong response can be obtained after a new antigenic stimulation, with a substantial proportion of IgM. It is concluded that persistent antigenic stimulation plays a major role in the change from IgM to IgG synthesis. PMID:4212089

  7. Patterns of esophageal inhibition during swallowing, pharyngeal stimulation, and transient LES relaxation. Lower esophageal sphincter.

    PubMed

    Pouderoux, Philippe; Verdier, Eric; Kahrilas, Peter J

    2003-02-01

    Lower esophageal sphincter (LES) relaxation and esophageal body inhibition co-occur during esophageal peristalsis but not necessarily during pharyngeal stimulation or transient LES relaxation (tLESR). This study examined these relationships and the impact on reflux. Nine young volunteers were studied. An artificial high-pressure zone (HPZ) was established, and pH was recorded 8 and 5 cm proximal to the LES. Pharyngeal stimulation was by water injection and gastric distension with liquid or gas. Peristalsis, pharyngeal stimulation, and spontaneous events were recorded. Swallowing relaxed the LES in 100% of trials (the HPZ in 80%) and caused no reflux. Pharyngeal stimulation relaxed the LES in two-thirds of trials, had no effect on the HPZ, and caused no reflux. Gastric distension was associated with 117 tLESRs, 48% with acid reflux, and 32% with gas reflux; there was no effect on the HPZ. We conclude that LES relaxation is a necessary but not sufficient condition for reflux. LES relaxation and esophageal body inhibition are independent events that may be concurrent (swallowing) or dissociated (tLESR).

  8. Histamine stimulates chloride secretion in omeprazole-inhibited frog gastric mucosa

    SciTech Connect

    McGreevy, J.; Barton, R.; Housinger, T.

    1986-03-05

    Omeprazole (OME) stops hydrogen ion (H) secretion in the histamine (HIST)-stimulated gastric mucosa while the chloride (Cl) which had accompanied the H continues to be pumped into the lumen. This finding suggests that the Cl pump is independent of the H/K ATP-ase driven H pump. To test this hypothesis, 16 Ussing-chambered frog mucosas were exposed to OME prior to HIST stimulation. If the Cl pump is independent, HIST should stimulate Cl secretion in the OME-inhibited mucosa. A 1 hr control (CON) interval preceded exposure to OME (10/sup -4/M) in the nutrient solution. Potential difference (PD), short-circuit current (Isc), resistance (R), H flux (J/sup H/) and Cl flux (J/sup Cl/ with /sup 36/Cl) were measured every 15 min. After 1 hr of OME exposure, HIST (10/sup -5/M) was added to the nutrient solution. The findings demonstrate that HIST stimulates Cl secretion in the OME-inhibited bullfrog gastric mucosa.

  9. Cannabinoids inhibit the activation of ERK MAPK in PMA/Io-stimulated mouse splenocytes.

    PubMed

    Faubert Kaplan, Barbara L; Kaminski, Norbert E

    2003-10-01

    The mechanism of action of immune suppression by cannabinoids involves suppression of interleukin-2 (IL-2) production in phorbol ester plus calcium ionophore (PMA/Io)-stimulated lymphocytes. This decrease in IL-2 was due to inhibition of activator protein-1 (AP-1) and nuclear factor of activated T cells (NF-AT) transcription factors, both of which depend on proteins that are regulated by the extracellular signal-regulated kinase subgroup of the mitogen-activated protein kinases (ERK MAPK). Thus, the objective of the present study was to characterize the effects of cannabinoid compounds on ERK MAPK under conditions where IL-2 expression was suppressed. Using the MEK inhibitor PD098059 in order to assess the role of ERK MAPK in PMA/Io-stimulated splenocytes (SPLC), it was determined that IL-2 production and expression of c-fos and c-jun nuclear protein expression depended on activation of ERK MAPK. In response to PMA/Io, expression of nuclear phosphorylated ERK MAPK was rapidly induced, peaked at approximately 15 min, and was sustained for up to 240 min. Pretreatment with cannabinol (CBN) inhibited expression of phosphorylated ERK MAPK at several time points up to 240 min post cellular activation. Furthermore, WIN-55212-2, a synthetic cannabinoid, inhibited expression of phosphorylated ERK MAPK at 240 min post cellular activation. CBN did not induce activation of ERK MAPK in the absence of PMA/Io. Collectively, these studies suggest that cannabinoid-induced inhibition of IL-2 in PMA/Io-stimulated splenocytes might be due, in part, to inhibition of ERK MAPK activation.

  10. Comparison of rat and dog models of vasodilatation and lipolysis for the calculation of a therapeutic index for GPR109A agonists.

    PubMed

    Carballo-Jane, Ester; Gerckens, Lynn S; Luell, Silvi; Parlapiano, Allison S; Wolff, Michael; Colletti, Steven L; Tata, James R; Taggart, Andrew K P; Waters, M Gerard; Richman, Jeremy G; McCann, Margaret E; Forrest, Michael J

    2007-01-01

    GPR109A is the receptor mediating both the antilipolytic and vasodilatory effects of nicotinic acid. In order to develop agonists for GPR109A with improved therapeutic indices we have sought to optimize animal models that evaluate both nicotinic acid-mediated inhibition of lipolysis and stimulation of vasodilatation. The rat and the dog have previously been used to study the antilipolytic effects of nicotinic acid, but no optimal vasodilatation model exits in either species. We have developed a vasodilatation model in the rat that measures changes in ear perfusion using laser Doppler flowmetry. In the dog, we have developed a model of vasodilatation measuring changes in red color values in the ear, using a spectrocolorimeter. Effects of GPR109A agonists on lipolysis were measured in both species after oral dosing of compounds, and measuring plasma levels of free fatty acids. In both rat and dog, GPR109A agonists induce dose- and time-dependent vasodilatation, similar to that observed in humans. Vasodilatation is inhibited in both species with cyclooxygenase inhibitors or a specific DP1 receptor antagonist, indicating that, as in man, nicotinic acid-induced vasodilatation in rats and dogs is mainly mediated by the release of PGD(2). Our results show that both rat and dog are useful models for the characterization of GPR109A agonists. A therapeutic index for GPR109A agonists can be calculated in either species.

  11. A potassium ionophore (Nigericin) inhibits stimulation of human lymphocytes by mitogens

    PubMed Central

    1978-01-01

    Nigericin, an ionophore that exchanges K+ for H+ across most biologic membranes, reversibly inhibited the proliferative response of human lymphocytes to phytohemagglutinin (PHA). Inhibition occurred at nigericin concentrations of 10(-8) M or greater, and only during the early event of mitogenesis. There was no effect if nigericin was added 24 h or later after the initiation of PHA-stimulated cultures. The effect was not the result of toxicity or impaired mitochondrial respiration. At similar concentrations, nigericin also inhibited lymphocyte responses in mixed lymphocyte cultures and to other mitogens including concanavalin A, pokeweed mitogen, and the calcium ionophore A23187. The findings support the view that one or more transmembranous events, mediated by changes in cation flux and/or membrane potential, are critical in the initial stages of lymphocyte mitogenesis. PMID:146727

  12. Sustained Inhibition of Proliferative Response After Transient FGF Stimulation Is Mediated by Interleukin 1 Signaling.

    PubMed

    Poole, Ashleigh; Kacer, Doreen; Cooper, Emily; Tarantini, Francesca; Prudovsky, Igor

    2016-03-01

    Transient FGF stimulation of various cell types results in FGF memory--a sustained blockage of efficient proliferative response to FGF and other growth factors. FGF memory establishment requires HDAC activity, indicating its epigenetic character. FGF treatment stimulates proinflammatory NFκB signaling, which is also critical for FGF memory formation. The search for FGF-induced mediators of FGF memory revealed that FGF stimulates HDAC-dependent expression of the inflammatory cytokine IL1α. Similarly to FGF, transient cell treatment with recombinant IL1α inhibits the proliferative response to further FGF and EGF stimulation, but does not prevent FGF receptor-mediated signaling. Interestingly, like cells pretreated with FGF1, cells pretreated with IL1α exhibit enhanced restructuring of actin cytoskeleton and increased migration in response to FGF stimulation. IRAP, a specific inhibitor of IL 1 receptor, and a neutralizing anti-IL1α antibody prevent the formation of FGF memory and rescue an efficient proliferative response to FGF restimulation. A similar effect results following treatment with the anti-inflammatory agents aspirin and dexamethasone. Thus, FGF memory is mediated by proinflammatory IL1 signaling. It may play a role in the limitation of proliferative response to tissue damage and prevention of wound-induced hyperplasia.

  13. Inhibition of colony-stimulating factor (CSF) production by postburn serum: negative feedback inhibition mediated by lactoferrin.

    PubMed

    Peterson, V M; Ambruso, D R; Emmett, M; Bartle, E J

    1988-11-01

    Fatal infections in severely burned patients are often preceded by a decline in the production of colony-stimulating factor (CSF) and the proliferation of granulocyte-macrophage stem cells (CFU-GM), and overwhelming sepsis is often associated with leukopenia. The underlying mechanisms accounting for these granulopoietic defects are poorly understood, but the fact that postburn serum has been shown to inhibit CSF production suggests that a humoral factor or factors may play a role. Previous work has demonstrated that plasma levels of lactoferrin (LF), a known inhibitor of CSF production, are elevated following burn injury. To determine if LF is responsible for serum-mediated inhibition of CSF production, serial plasma levels of LF were measured in 18 burn patients using an enzyme-linked immunoabsorbent assay (ELISA). LF was elevated within 24 hours of injury and was associated with an absolute granulocytosis which rapidly declined, reaching a nadir at postburn days 3 through 5. Postburn serum, especially when collected during the first 24 hours following burn injury, inhibited in vitro CSF production by normal human peripheral blood mononuclear cells. Pre-incubation of postburn serum with an LF antibody restored normal CSF production. These data suggest that LF may play an important role in the regulation of postburn granulopoiesis.

  14. ADIPOSE TRIGLYCERIDE LIPASE REGULATES BASAL LIPOLYSIS AND LIPID DROPLET SIZE IN ADIPOCYTES

    PubMed Central

    Miyoshi, Hideaki; Perfield, James W.; Obin, Martin S.; Greenberg, Andrew S.

    2008-01-01

    In adipocytes, lipid droplet (LD) size reflects a balance of triglyceride synthesis (lipogenesis) and hydrolysis (lipolysis). Perilipin A (Peri A), is the most abundant phosphoprotein on the surface of adipocyte LDs and has a crucial role in lipid storage and lipolysis. Adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) are the major rate-determining enzymes for lipolysis in adipocytes. Each of these proteins (Peri A, ATGL and HSL) have been demonstrated to regulate lipid storage and release in the adipocyte. However, in the absence of PKA stimulation (basal state), the lipases (ATGL and HSL) are located mainly in the cytoplasm, and their contribution to basal rates of lipolysis and influence on LD size are poorly understood. In this study, we utilize an adenoviral system to knockdown or overexpress ATGL and HSL in an engineered model system of adipocytes in the presence or absence of Peri A. We are able to demonstrate in our experimental model system, that in the basal state, LD size, triglyceride storage, and fatty acid release are mainly influenced by expression of ATGL. These results demonstrate for the first time the relative contributions of ATGL, HSL, and Peri A on determination of LD size in the absence of PKA-stimulation. PMID:18980248

  15. Major role of adipocyte prostaglandin E2 in lipolysis-induced macrophage recruitment[S

    PubMed Central

    Hu, Xiaoqian; Cifarelli, Vincenza; Sun, Shishuo; Kuda, Ondrej; Abumrad, Nada A.; Su, Xiong

    2016-01-01

    Obesity induces accumulation of adipose tissue macrophages (ATMs), which contribute to both local and systemic inflammation and modulate insulin sensitivity. Adipocyte lipolysis during fasting and weight loss also leads to ATM accumulation, but without proinflammatory activation suggesting distinct mechanisms of ATM recruitment. We examined the possibility that specific lipid mediators with anti-inflammatory properties are released from adipocytes undergoing lipolysis to induce macrophage migration. In the present study, we showed that conditioned medium (CM) from adipocytes treated with forskolin to stimulate lipolysis can induce migration of RAW 264.7 macrophages. In addition to FFAs, lipolytic stimulation increased release of prostaglandin E2 (PGE2) and prostaglandin D2 (PGD2), reflecting cytosolic phospholipase A2 α activation and enhanced cyclooxygenase (COX) 2 expression. Reconstituted medium with the anti-inflammatory PGE2 potently induced macrophage migration while different FFAs and PGD2 had modest effects. The ability of CM to induce macrophage migration was abolished by treating adipocytes with the COX2 inhibitor sc236 or by treating macrophages with the prostaglandin E receptor 4 antagonist AH23848. In fasted mice, macrophage accumulation in adipose tissue coincided with increases of PGE2 levels and COX1 expression. Collectively, our data show that adipocyte-originated PGE2 with inflammation suppressive properties plays a significant role in mediating ATM accumulation during lipolysis. PMID:26912395

  16. Inhibition of midbrain-evoked tonic and rhythmic motor activity by cutaneous stimulation in decerebrate cats.

    PubMed

    Beyaert, C A; Haouzi, P; Marchal, F

    2003-03-01

    The effect of mechanical and electrical stimulation of cervical cutaneous afferents was analysed on both the centrally induced tonic and rhythmic activities in hindlimb antagonist muscle nerves of 16 decerebrate paralysed cats. Electrical stimulation of dorsal midbrain evoked in the nerve to the tibialis anterior muscle (TAn) either rhythmic discharges (n=14), associated with tonic discharges in ten cats, or only tonic discharges (n=4). Centrally induced activity in the ipsilateral nerve to gastrocnemius medialis (GMn) occurred in fewer cats (n=12) and displayed similar patterns as in TAn. Manual traction of the scruff of the neck reduced the TAn tonic and rhythmic discharges (n=6) by 73% (P<0.05) and 71% (P<0.05), respectively, and reduced only the tonic component of GMn discharges (by 41%, n=3). Electrical stimulation (impulses 0.1-0.5 ms, 50 Hz) of cervical nerves belonging to C5 or C6 dermatomes, the intensity (0.4-4 mA) of which induced minimal inhibition of both TAn and GMn discharges, reduced significantly the tonic component of TAn discharges (by 39%, n=4). At higher intensities of electrical cervical nerve stimulation (2-6 mA) inducing maximal inhibitory effect, both tonic and rhythmic activities in TAn and GMn were both significantly reduced by, respectively, 81% and 94% in TAn (n=7), and by 49% and 43% in GMn (n=7). Electrical cervical nerve stimulation consistently reduced the isolated tonic discharge in TAn by 66% (n=4, P<0.05) and in GMn by 23% (n=3) when present. Thus the tonic component was more sensitive to inhibition than the rhythmic component of hindlimb muscle nerve activity.

  17. Protein kinase C activation inhibits eosinophil degranulation through stimulation of intracellular cAMP production.

    PubMed

    Ezeamuzie, Charles I; Taslim, Najla

    2004-11-01

    The mechanism of inhibition of eosinophil degranulation by protein kinase C (PKC) was investigated in complement C5a (C5a)-stimulated degranulation of highly purified human eosinophils using the specific PKC activator - phorbol 12-myristate 13-acetate (PMA). C5a-induced release of eosinophil peroxidase and eosinophil cationic protein was potently inhibited in a concentration-dependent manner by PMA (IC(50): 3 and 5 nM, respectively). The inhibition by PMA, but not histamine, was significantly reversed by the specific, but isoform nonselective, PKC inhibitor Ro 31-8220 (1 microM). In the presence of phosphodiesterase inhibitor rolipram (5 microM), PMA stimulated a pronounced concentration-dependent increase in intracellular cAMP, with a potency 400 times that of histamine (EC(50): 55 nM vs 22.5 microM). The inactive PMA analogue, 4alpha-PMA, had no such effect. The cAMP production by PMA, but not histamine, was significantly reversed by Ro 31-8220 (1 microM) and the selective inhibitor of the novel PKCdelta, rottlerin (1-3 microM), but not the selective inhibitor of the classical PKC isoforms, Gö 6976 (0.01-0.1 microM). Western blot analysis revealed the presence of six PKC isoforms (alpha, betaI, betaII, delta, iota and zeta) in isolated eosinophils. Chelation of internal or external calcium had no effect on PMA-induced cAMP response, but abolished that induced by histamine. There was a good correlation between increase in intracellular cAMP and inhibition of degranulation. These results show, for the first time, that in human eosinophils, PMA, via activation of PKCdelta isoform, can stimulate cAMP production, and that this may be the basis for its potent anti-degranulatory effect.

  18. Protein kinase C activation inhibits eosinophil degranulation through stimulation of intracellular cAMP production

    PubMed Central

    Ezeamuzie, Charles I; Taslim, Najla

    2004-01-01

    The mechanism of inhibition of eosinophil degranulation by protein kinase C (PKC) was investigated in complement C5a (C5a)-stimulated degranulation of highly purified human eosinophils using the specific PKC activator – phorbol 12-myristate 13-acetate (PMA). C5a-induced release of eosinophil peroxidase and eosinophil cationic protein was potently inhibited in a concentration-dependent manner by PMA (IC50: 3 and 5 nM, respectively). The inhibition by PMA, but not histamine, was significantly reversed by the specific, but isoform nonselective, PKC inhibitor Ro 31-8220 (1 μM). In the presence of phosphodiesterase inhibitor rolipram (5 μM), PMA stimulated a pronounced concentration-dependent increase in intracellular cAMP, with a potency 400 times that of histamine (EC50: 55 nM vs 22.5 μM). The inactive PMA analogue, 4α-PMA, had no such effect. The cAMP production by PMA, but not histamine, was significantly reversed by Ro 31-8220 (1 μM) and the selective inhibitor of the novel PKCδ, rottlerin (1–3 μM), but not the selective inhibitor of the classical PKC isoforms, Gö 6976 (0.01–0.1 μM). Western blot analysis revealed the presence of six PKC isoforms (α, βI, βII, δ, ι and ζ) in isolated eosinophils. Chelation of internal or external calcium had no effect on PMA-induced cAMP response, but abolished that induced by histamine. There was a good correlation between increase in intracellular cAMP and inhibition of degranulation. These results show, for the first time, that in human eosinophils, PMA, via activation of PKCδ isoform, can stimulate cAMP production, and that this may be the basis for its potent anti-degranulatory effect. PMID:15504748

  19. Dopamine Inhibits Angiotensin-Stimulated Aldosterone Biosynthesis in Bovine Adrenal Cells

    PubMed Central

    Mc Kenna, Terence J.; Island, Donald P.; Nicholson, Wendell E.; Liddle, Grant W.

    1979-01-01

    The possibility that dopamine may play a role in the in vivo control of aldosterone production in man was suggested to us by reports from others; (a) that bromocriptine, a dopaminergic agonist, inhibits the aldosterone response to diuresis and to the infusion of angiotensin or ACTH; and (b) that metaclopramide, a dopamine blocking agent, causes elevations in plasma aldosterone levels. To determine whether such effects were direct or indirect, we examined the action of dopamine on aldosterone biosynthesis in isolated, bovine adrenal cells. Dopamine significantly inhibits the aldosterone response to angiotensin (P < 0.001), but does not influence basal aldosterone biosynthesis. It has previously been reported that angiotensin stimulates both the early and late phases of aldosterone biosynthesis. The present experiments demonstrated that the enhancing effect of angiotensin on the conversion of deoxycorticosterone to aldosterone (late phase of aldosterone biosynthesis) was almost completely inhibited by dopamine (P < 0.001). A significant inhibitory effect of dopamine (10 nM) was seen even when aldosterone biosynthesis was stimulated by a grossly supraphysiological concentration of angiotensin II (10 μM). However, these studies did not demonstrate any direct effect of dopamine on the early phase of aldosterone biosynthesis (cholesterol to pregnenolone) basally or when stimulated, or on the late phase of aldosterone biosynthesis under basal conditions. These in vitro studies suggest a direct inhibitory role for dopamine on the late phase of aldosterone biosynthesis, which may account for the in vivo inhibition of the aldosterone response to angiotensin in subjects treated with a dopaminergic agent. PMID:447857

  20. Corticosterone inhibition of osmotically stimulated vasopressin from hypothalamic-neurohypophysial explants.

    PubMed

    Papanek, P E; Sladek, C D; Raff, H

    1997-01-01

    Glucocorticoids inhibit and glucocorticoid deficiency increases vasopressin (AVP) release in vivo. To determine whether the effect of glucocorticoids is hypothalamic and mediated via a glucocorticoid receptor, explants of the hypothalamic-neurohypophysial system were used to measure AVP release during agonist and antagonist exposure. Explants from adult rats, which contained AVP neurons of the supraoptic nucleus with axonal projections terminating in the neural lobe but excluded the paraventricular nucleus, were perifused with an osmotic stimulus (increase of 5 mosmol/h over 6 h) in the absence or presence of corticosterone (100 micrograms/dl) or with corticosterone (100 micrograms/dl) in the absence or presence of the glucocorticoid antagonist RU-486 (10 microM). AVP release was not increased during osmotic stimulation in the presence of corticosterone (Cort) and was 20-30% lower than osmotically stimulated release observed in the absence of Cort. RU-486 reversed the inhibitory effect of corticosterone on AVP release. No changes in AVP mRNA content were detected. These results suggest that Cort inhibits osmotically stimulated AVP release by a direct effect within the hypothalamus and/or neurohypophysis. This effect is mediated by the glucocorticoid receptor through either genomic or nongenomic mechanisms.

  1. Ethanol stimulates superoxide production and inhibits phorbol ester induced superoxide production in alveolar macrophages

    SciTech Connect

    Dorio, R.J.; Hoek, J.B.; Forman, H.J.; Rubin, E.

    1986-05-01

    Ethanol stimulates superoxide (O/sub 2//sup -/) production in rat alveolar macrophages. Increasing the ethanol concentration from 75 to 500 mM produces a linear dose response curve, generating between 10 and 30 pmol O/sub 2//sup -//min/10/sup 6/ cells. Thus, ethanol is a weak agonist of O/sub 2//sup -/ in these cells. Pretreatment with ethanol in the same concentration range results in a dose and time dependent inhibition of O/sub 2//sup -/ production by phorbol-12-myristate-13-acetate (PMA). 100 mM ethanol inhibits PMA (100 ng/ml)-induced O/sub 2//sup -/ production by 60% after 5 minutes and by 80% after 30 minutes of preincubation. At lower concentrations (10-25 mM), however, ethanol causes a synergistic stimulation of PMA-induced O/sub 2//sup -/ production. Preincubation for 15 minutes with 10 mM ethanol results in a 20% increase in PMA-induced O/sub 2//sup -/ production. Synergism between PMA and ethanol is seen at ethanol concentrations which do not result in O/sub 2//sup -/ production by ethanol alone. This synergism is abolished by a 15 minute preincubation of the cells in EGTA. Thus, ethanol acts as a weak agonist for O/sub 2//sup -/ production and interacts significantly with PMA-induced stimulation of O/sub 2//sup -/ production.

  2. Eosinophil cationic protein stimulates and major basic protein inhibits airway mucus secretion.

    PubMed

    Lundgren, J D; Davey, R T; Lundgren, B; Mullol, J; Marom, Z; Logun, C; Baraniuk, J; Kaliner, M A; Shelhamer, J H

    1991-03-01

    Possible roles of eosinophil (EO) products in modulating the release of mucus from airway explants were investigated. Cell- and membrane-free lysates from purified human EOs (1 to 20 x 10(5)) caused a dose-dependent release of respiratory glycoconjugates (RGC) from cultured feline tracheal explants. Crude extracts from isolated EO granules also stimulated RGC release, suggesting that a granular protein might be responsible. Three proteins derived from EO granules, EO-derived neurotoxin, EO cationic protein (ECP), and major basic protein (MBP) were separated by sequential sizing and affinity chromatography. ECP (0.025 to 25 micrograms/ml) caused a dose-dependent increase in RGC release from both feline and human airway explants and also stimulated the release of the serous cell-marker, lactoferrin, from human bronchial explants. EO-derived neurotoxin (0.025 to 50 micrograms/ml) failed to affect RGC release, whereas MBP (50 micrograms/ml) significantly inhibited RGC release from feline explants. Thus, ECP stimulates RGC and lactoferrin release from airway explants, whereas MBP inhibits RGC release.

  3. Paired Associative Stimulation Induces Change in Presynaptic Inhibition of Ia Terminals in Wrist Flexors in Humans

    PubMed Central

    Russmann, Heike; Shamim, Ejaz A.; Meunier, Sabine; Hallett, Mark

    2010-01-01

    Enhancements in the strength of corticospinal projections to muscles are induced in conscious humans by paired associative stimulation (PAS) to the motor cortex. Although most of the previous studies support the hypothesis that the increase of the amplitude of motor evoked potentials (MEPs) by PAS involves long-term potentiation (LTP)-like mechanism in cortical synapses, changes in spinal excitability after PAS have been reported, suggestive of parallel modifications in both cortical and spinal excitability. In a first series of experiments (experiment 1), we confirmed that both flexor carpi radialis (FCR) MEPs and FCR H reflex recruitment curves are enhanced by PAS. To elucidate the mechanism responsible for this change in the H reflex amplitude, we tested, using the same subjects, the hypothesis that enhanced H reflexes are caused by a down-regulation of the efficacy of mechanisms controlling Ia afferent discharge, including presynaptic Ia inhibition and postactivation depression. To address this question, amounts of both presynaptic Ia inhibition of FCR Ia terminals (D1and D2 inhibitions methods; experiment 2) and postactivation depression (experiment 3) were determined before and after PAS. Results showed that PAS induces a significant decrease of presynaptic Ia inhibition of FCR terminals, which was concomitant with the facilitation of the H reflex. Postactivation depression was unaffected by PAS. It is argued that enhancement of segmental excitation by PAS relies on a selective effect of PAS on the interneurons controlling presynaptic inhibition of Ia terminals. PMID:20538768

  4. Gastric electrical stimulation optimized to inhibit gastric motility reduces food intake in dogs.

    PubMed

    Song, Geng-Qing; Zhu, Hongbing; Lei, Yong; Yuan, Charlene; Starkebaum, Warren; Yin, Jieyun; Chen, Jiande D Z

    2015-06-01

    The aim of this study was to test the hypothesis that that a method of gastric electrical stimulation (GES) optimized to inhibit gastric motility was effective in reducing food intake in dogs. Female dogs with a gastric cannula and gastric serosal electrodes were studied in three experiments: (1) to determine the best parameters and locations of GES in inhibiting gastric tone, slow waves, and contractions in dogs;( 2) to investigate the reproducibility of the inhibitory effects of GES; and (3) to study the effect of the GES method on food intake in dogs. (1) For GES to exert significant effects on gastric motility, a pulse width of ≥2 ms was required, and with other appropriate inhibitory parameters, GES was able to increase gastric volume by 190.4 %, reduce antral contractions by 39.7 %, and decrease the percentage of normal slow waves by 47.6 %. In addition, the inhibitory effect of GES was more potent with the stimulation electrodes placed along the lesser or greater curvature than placed in the middle, and more potent with the electrodes placed in the distal stomach than in the proximal stomach; (2) the inhibitory effects of GES on gastric motility were reproducible; (3) the GES method optimized to inhibit gastric motility produced a 20 % reduction in food intakes in non-obese dogs. GES with appropriate parameters inhibits gastric motility, and the effects are reproducible. The GES method optimized to inhibit gastric motility reduces food intake in healthy dogs and may have a therapeutic potential for treating obesity.

  5. Alternative Mechanism for White Adipose Tissue Lipolysis after Thermal Injury

    PubMed Central

    Diao, Li; Patsouris, David; Sadri, Ali-Reza; Dai, Xiaojing; Amini-Nik, Saeid; Jeschke, Marc G

    2015-01-01

    Extensively burned patients often suffer from sepsis, a complication that enhances postburn hypermetabolism and contributes to increased incidence of multiple organ failure, morbidity and mortality. Despite the clinical importance of burn sepsis, the molecular and cellular mechanisms of such infection-related metabolic derangements and organ dysfunction are still largely unknown. We recently found that upon endoplasmic reticulum (ER) stress, the white adipose tissue (WAT) interacts with the liver via inflammatory and metabolic signals leading to profound hepatic alterations, including hepatocyte apoptosis and hepatic fatty infiltration. We therefore hypothesized that burn plus infection causes an increase in lipolysis of WAT after major burn, partially through induction of ER stress, contributing to hyperlipidemia and profound hepatic lipid infiltration. We used a two-hit rat model of 60% total body surface area scald burn, followed by intraperitoneal (IP) injection of Pseudomonas Aeruginosa-derived lipopolysaccharide (LPS) 3 d postburn. One day later, animals were euthanized and liver and epididymal WAT (EWAT) samples were collected for gene expression, protein analysis and histological study of inflammasome activation, ER stress, apoptosis and lipid metabolism. Our results showed that burn plus LPS profoundly increased lipolysis in WAT associated with significantly increased hepatic lipid infiltration. Burn plus LPS augmented ER stress by upregulating CHOP and activating ATF6, inducing NLRP3 inflammasome activation and leading to increased apoptosis and lipolysis in WAT with a distinct enzymatic mechanism related to inhibition of AMPK signaling. In conclusion, burn sepsis causes profound alterations in WAT and liver that are associated with changes in organ function and structure. PMID:26736177

  6. Effect of the water extracts of propolis on stimulation and inhibition of different cells

    PubMed Central

    Vahedy, Fatemeh; Seyyedin, Mohammad; Jomehzadeh, Hamid Reza; Bozary, Kazem

    2007-01-01

    The water extracts of propolis (WEP) could inhibit growth of different cell lines namely McCoy, HeLa, SP2/0, HEp-2, and BHK21 and stimulate growth of normal cell named human lymphocyte, rat kidney, rat liver, and rat spleen. In these experiments 1 and 2 mg of WEP were added to 1 ml RPMI media with 5% FCS. Cell counts and cell viability of propolis-treated and propolis-free cells were assessed by Trypan blue dye exclusion test and MTT assay. The results showed that in case of McCoy, HeLa, SP20, HEp-2, and BHK21 cell lines, the water extracts of propolis could inhibit cell growth as well as reduction on size of the cells. In contrast the same amount of WEP could stimulate growth of normal cells up to 60% with the same concentration used for cell lines. Thus our study indicates that although WEP consists only of the soluble part of propolis, it enables to inhibit different cell lines and increase growth of normal cells. This indicates also that WEP contains the specific compounds with bioactivity against cell lines. Although propolis contain different number of compounds it is clear that WEP has enough biological compounds useful for the treatment of some diseases, medical and related applications. PMID:19003017

  7. Metformin (Glucophage) inhibits tyrosine phosphatase activity to stimulate the insulin receptor tyrosine kinase.

    PubMed

    Holland, William; Morrison, Thomas; Chang, Ying; Wiernsperger, Nicholas; Stith, Bradley J

    2004-06-01

    Metformin is a commonly used anti-diabetic but whether its mechanism involves action on the insulin receptor or on downstream events is still controversial. With a time course that was slow compared with insulin action, metformin increased tyrosine phosphorylation of the regulatory domain of the insulin receptor (specifically, tyrosine residues 1150 and 1151). In a direct action, therapeutic levels of metformin stimulated the tyrosine kinase activity of the soluble intracellular portion of the beta subunit of the human insulin receptor toward a substrate derived from the insulin receptor regulatory domain. However, metformin did not alter the order of substrate phosphorylation by the insulin receptor kinase. Using a Xenopus oocyte preparation, we simultaneously recorded tyrosine kinase and phosphatase activities that regulate the insulin receptor by measuring the tyrosine phosphorylation and dephosphorylation of peptides derived from the regulatory domain of the human insulin receptor. In an indirect stimulation of the insulin receptor, metformin inhibited endogenous tyrosine phosphatases and purified human protein tyrosine phosphatase 1B that dephosphorylate and inhibit the insulin receptor kinase. Thus, there was evidence that metformin acted directly upon the insulin receptor and indirectly through inhibition of tyrosine phosphatases.

  8. Transcranial direct current stimulation of superior medial frontal cortex disrupts response selection during proactive response inhibition.

    PubMed

    Bender, Angela D; Filmer, Hannah L; Dux, Paul E

    2016-10-24

    Cognitive control is a vital executive process that is involved in selecting, generating, and maintaining appropriate, goal-directed behaviour. One operation that draws heavily on this resource is the mapping of sensory information to appropriate motor responses (i.e., response selection). Recently, a transcranial direct current stimulation (tDCS) study demonstrated that the left posterior lateral prefrontal cortex (pLPFC) is casually involved in response selection and response selection training. Correlational brain imaging evidence has also implicated the superior medial frontal cortex (SMFC) in response selection, and there is causal evidence that this brain region is involved in the proactive modulation of response tendencies when occasional stopping is required (response inhibition). However, to date there is only limited causal evidence that implicates the SMFC in response selection. Here, we investigated the role of SMFC in response selection, response selection training (Experiment 1) and response selection when occasional response inhibition is anticipated (Experiments 2 and 3) by employing anodal, cathodal, and sham tDCS. Cathodal stimulation of the SMFC modulated response selection by increasing reaction times in the context of proactive response inhibition. Our results suggest a context dependent role of the SMFC in response selection and hint that task set can influence the interaction between the brain and behaviour.

  9. TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation.

    PubMed

    Yang, Gui-Li; Zhao, Zilong; Qin, Ting-Ting; Wang, Dong; Chen, Lijuan; Xiang, Rong; Xi, Zhen; Jiang, Rongcai; Zhang, Zhi-Song; Zhang, Jianning; Li, Lu-Yuan

    2017-02-09

    Vascular hyperpermeability is critical in ischemic diseases, including stroke and myocardial infarction, as well as in inflammation and cancer. It is well known that the VEGF-VEGFR2 signaling pathways are pivotal in promoting vascular permeability; however, counterbalancing mechanisms that restrict vascular permeability to maintain the integrity of blood vessels, are not yet fully understood. We report that TNF superfamily member 15 (TNFSF15), a cytokine largely produced by vascular endothelial cells and a specific inhibitor of the proliferation of these same cells, can inhibit VEGF-induced vascular permeability in vitro and in vivo, and that death receptor 3 (DR3), a cell surface receptor of TNFSF15, mediates TNFSF15-induced dephosphorylation of VEGFR2. Src homology region 2 domain-containing phosphatase-1 (SHP-1) becomes associated with DR3 upon TNFSF15 interaction with the latter. In addition, a protein complex consisting of VEGFR2, DR3, and SHP-1 is formed in response to the effects of TNFSF15 and VEGF on endothelial cells. It is plausible that this protein complex provides a structural basis for the molecular mechanism in which TNFSF15 induces the inhibition of VEGF-stimulated vascular hyperpermeability.-Yang, G.-L., Zhao, Z., Qin, T.-T., Wang, D., Chen, L., Xiang, R., Xi, Z., Jiang, R., Zhang, Z.-S., Zhang, J., Li. L.-Y. TNFSF15 inhibits VEGF-stimulated vascular hyperpermeability by inducing VEGFR2 dephosphorylation.

  10. Inhibition of fatty acid and cholesterol synthesis by stimulation of AMP-activated protein kinase.

    PubMed

    Henin, N; Vincent, M F; Gruber, H E; Van den Berghe, G

    1995-04-01

    AMP-activated protein kinase is a multisubstrate protein kinase that, in liver, inactivates both acetyl-CoA carboxylase, the rate-limiting enzyme of fatty acid synthesis, and 3-hydroxy-3-methyl-glutaryl-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. AICAR (5-amino 4-imidazolecarboxamide ribotide, ZMP) was found to stimulate up to 10-fold rat liver AMP-activated protein kinase, with a half-maximal effect at approximately 5 mM. In accordance with previous observations, addition to suspensions of isolated rat hepatocytes of 50-500 microM AICAriboside, the nucleoside corresponding to ZMP, resulted in the accumulation of millimolar concentrations of the latter. This was accompanied by a dose-dependent inactivation of both acetyl-CoA carboxylase and 3-hydroxy-3-methylglutaryl-CoA reductase. Addition of 50-500 microM AICAriboside to hepatocyte suspensions incubated in the presence of various substrates, including glucose and lactate/pyruvate, caused a parallel inhibition of both fatty acid and cholesterol synthesis. With lactate/pyruvate (10/1 mM), half-maximal inhibition was obtained at approximately 100 microM, and near-complete inhibition at 500 microM AICAriboside. These findings open new perspectives for the simultaneous control of triglyceride and cholesterol synthesis by pharmacological stimulators of AMP-activated protein kinase.

  11. Ascorbic acid participates in a general mechanism for concerted glucose transport inhibition and lactate transport stimulation.

    PubMed

    Castro, Maite A; Angulo, Constanza; Brauchi, Sebastián; Nualart, Francisco; Concha, Ilona I

    2008-11-01

    In this paper, we present a novel function for ascorbic acid. Ascorbic acid is an important water-soluble antioxidant and cofactor in various enzyme systems. We have previously demonstrated that an increase in neuronal intracellular ascorbic acid is able to inhibit glucose transport in cortical and hippocampal neurons. Because of the presence of sodium-dependent vitamin C transporters, ascorbic acid is highly concentrated in brain, testis, lung, and adrenal glands. In this work, we explored how ascorbic acid affects glucose and lactate uptake in neuronal and non-neuronal cells. Using immunofluorescence and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, the expression of glucose and ascorbic acid transporters in non-neuronal cells was studied. Like neurons, HEK293 cells expressed GLUT1, GLUT3, and SVCT2. With radioisotope-based methods, only intracellular ascorbic acid, but not extracellular, inhibits 2-deoxyglucose transport in HEK293 cells. As monocarboxylates such as pyruvate and lactate, are important metabolic sources, we analyzed the ascorbic acid effect on lactate transport in cultured neurons and HEK293 cells. Intracellular ascorbic acid was able to stimulate lactate transport in both cell types. Extracellular ascorbic acid did not affect this transport. Our data show that ascorbic acid inhibits glucose transport and stimulates lactate transport in neuronal and non-neuronal cells. Mammalian cells frequently present functional glucose and monocarboxylate transporters, and we describe here a general effect in which ascorbic acid functions like a glucose/monocarboxylate uptake switch in tissues expressing ascorbic acid transporters.

  12. Acupuncture stimulation inhibits somato-renal sympathetic A- and C-reflexes in anesthetized rats.

    PubMed

    Li, Wei-Min; Wu, Gen-Cheng; Arita, Hideko; Hanaoka, Kazuo

    2002-01-01

    Stimulation of peripheral nerve afferent for example tibial nerve by a strong electrical stimulation (rectanfular wave with 20V amplitude; pulse duration of 0.5 ms, 0.3 pulses/sec) can evoke a discharge of the somato-sympathetic reflex which is recorded on the efferent of renal sympathetic nerve. The component of the somato-sympathetic reflex can be divided into two parts: one is related to the transmission of the myelinated afferent fibers with a short lantency (41+/-2 ms) and is defined A-reflex, the other is related to the transmission of the unmyelinated afferent fibers with a long latency (210+/-13 ms) and is defined C-reflex. In the present study, an acupuncture needle (diameter 0.34 mm) was inserted into the hind limbs of the rat, dorsolaterally at the area of acupoint: huantiao (GB30), at a depth of 4-5 mm and was twisted right and left twice every second during recording the somato-renal sympathetic reflex. It was found that acupuncture on the huantiao acupoint significantly inhibited both A- and C-reflexes. There was no different inhibition of the A- and C-reflexes by acupuncture on the right or left side. However acupuncture on the fore limbs of the rat dorsolaterally at the area of acupoint: quchi (LI11) showed no effect on neither A- nor C-reflexes. These results suggest that acupuncture at the same spinal segment of the acupoint inhibits the somatorenal sympathetic reflex.

  13. Deep brain stimulation mechanisms: beyond the concept of local functional inhibition.

    PubMed

    Deniau, Jean-Michel; Degos, Bertrand; Bosch, Clémentine; Maurice, Nicolas

    2010-10-01

    Deep brain electrical stimulation has become a recognized therapy in the treatment of a variety of motor disorders and has potentially promising applications in a wide range of neurological diseases including neuropsychiatry. Behavioural observation that electrical high-frequency stimulation of a given brain area induces an effect similar to a lesion suggested a mechanism of functional inhibition. In vitro and in vivo experiments as well as per operative recordings in patients have revealed a variety of effects involving local changes of neuronal excitability as well as widespread effects throughout the connected network resulting from activation of axons, including antidromic activation. Here we review current data regarding the local and network activity changes induced by high-frequency stimulation of the subthalamic nucleus and discuss this in the context of motor restoration in Parkinson's disease. Stressing the important functional consequences of axonal activation in deep brain stimulation mechanisms, we highlight the importance of developing anatomical knowledge concerning the fibre connections of the putative therapeutic targets.

  14. Bioactive Extract from Moringa oleifera Inhibits the Pro-inflammatory Mediators in Lipopolysaccharide Stimulated Macrophages.

    PubMed

    Fard, Masoumeh Tangestani; Arulselvan, Palanisamy; Karthivashan, Govindarajan; Adam, Siti Khadijah; Fakurazi, Sharida

    2015-10-01

    Inflammation is a well-known physiological response to protect the body against infection and restore tissue injury. Nevertheless, the chronic inflammation can trigger various inflammatory associated diseases/disorder. Moringa oleifera is a widely grown plant in most tropical countries and it has been recognized traditionally for several medicinal benefits. The objective of this study was to investigate the anti-inflammatory properties of M. oleifera extract on lipopolysaccharide (LPS) - stimulated macrophages. The anti-inflammatory effect of M. oleifera hydroethanolic bioactive leaves extracts was evaluated by assessing the inhibition of nitric oxide (NO) production during Griess reaction and the expression of pro-inflammatory mediators in macrophages. Interestingly, we found that M. oleifera hydroethanolic bioactive leaves extract significantly inhibited the secretion of NO production and other inflammatory markers such as prostaglandin E2, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β. Meanwhile, the bioactive extract has induced the production of IL-10 in a dose-dependent manner. In addition, M. oleifera hydroethanolic bioactive leaves extract effectively suppressed the protein expression of inflammatory markers inducible NO synthase, cyclooxygenase-2, and nuclear factor kappa-light-chain-enhancer of activated B-cells p65 in LPS-induced RAW264.7 macrophages in a dose-dependent manner. These findings support the traditional use of M. oleifera plant as an effective treatment for inflammation associated diseases/disorders. Hydroethanolic extracts of Moringa oleifera effectively inhibit the NO production in LPS induced inflammatory model.M. oleifera crude extracts successfully modulate the production of pro-inflammatory mediators in LPS stimulated macrophages.M. oleifera extracts suppressed the expression of inflammatory mediators in LPS stimulated macrophages.

  15. Glucose inhibition of epinephrine stimulation of hepatic gluconeogenesis by blockade of the alpha-receptor function.

    PubMed

    Kneer, N M; Bosch, A L; Clark, M G; Lardy, H A

    1974-11-01

    For isolated rat hepatocytes, glucagon, 3':5'-cyclic AMP, 3':5'-cyclic GMP, and epinephrine stimulate the rate of gluconeogenesis from substrates not involving pathways of mitochondrial metabolism. From estimation of the rates of glucose formation, fructose 6-phosphate phosphorylation, and lactate and pyruvate formation it is concluded that epinephrine and 3':5'-cyclic GMP stimulate gluconeogenesis from either galactose or fructose by influencing the rate of reactions involving fructose 6-phosphate in a manner similar to that already reported for glucagon and 3':5'-cyclic AMP. Each agent acts to inhibit flux through phosphofructokinase (EC 2.7.1.11) and enhance flux through fructose diphosphatase (EC 3.1.3.11), resulting in the re-direction of carbon from lactate and pyruvate formation to glucose synthesis. In addition to 3':5'-cyclic GMP, dibutyryl 3':5'-cyclic GMP, 8-bromo 3':5'-cyclic GMP, 8-benzyl-thio 3':5'-cyclic GMP and 8-(4-chlorophenyl)thio 3':5'-cyclic GMP stimulate glucose formation and inhibit lactate and pyruvate formation from galactose. Guanosine monophosphate and 2':3'-cyclic GMP are inactive. As the stimulatory effect of epinephrine is inhibited by phenoxybenzamine and not by propranolol, and is not simulated by isoproterenol, it is concluded that catecholamine activity is expressed through the alpha-receptor. Increased extracellular glucose concentration (>10 mM) decreases the stimulatory effect of epinephrine, 3':5'-cyclic GMP, and partially that of 3':5'-cyclic AMP but does not alter the efficacy of glucagon.

  16. Bioactive Extract from Moringa oleifera Inhibits the Pro-inflammatory Mediators in Lipopolysaccharide Stimulated Macrophages

    PubMed Central

    Fard, Masoumeh Tangestani; Arulselvan, Palanisamy; Karthivashan, Govindarajan; Adam, Siti Khadijah; Fakurazi, Sharida

    2015-01-01

    Introduction: Inflammation is a well-known physiological response to protect the body against infection and restore tissue injury. Nevertheless, the chronic inflammation can trigger various inflammatory associated diseases/disorder. Moringa oleifera is a widely grown plant in most tropical countries and it has been recognized traditionally for several medicinal benefits. Objectives: The objective of this study was to investigate the anti-inflammatory properties of M. oleifera extract on lipopolysaccharide (LPS) - stimulated macrophages. Materials and Methods: The anti-inflammatory effect of M. oleifera hydroethanolic bioactive leaves extracts was evaluated by assessing the inhibition of nitric oxide (NO) production during Griess reaction and the expression of pro-inflammatory mediators in macrophages. Results: Interestingly, we found that M. oleifera hydroethanolic bioactive leaves extract significantly inhibited the secretion of NO production and other inflammatory markers such as prostaglandin E2, tumor necrosis factor alpha, interleukin (IL)-6, and IL-1β. Meanwhile, the bioactive extract has induced the production of IL-10 in a dose-dependent manner. In addition, M. oleifera hydroethanolic bioactive leaves extract effectively suppressed the protein expression of inflammatory markers inducible NO synthase, cyclooxygenase-2, and nuclear factor kappa-light-chain-enhancer of activated B-cells p65 in LPS-induced RAW264.7 macrophages in a dose-dependent manner. Conclusion: These findings support the traditional use of M. oleifera plant as an effective treatment for inflammation associated diseases/disorders. SUMMARY Hydroethanolic extracts of Moringa oleifera effectively inhibit the NO production in LPS induced inflammatory model.M. oleifera crude extracts successfully modulate the production of pro-inflammatory mediators in LPS stimulated macrophages.M. oleifera extracts suppressed the expression of inflammatory mediators in LPS stimulated macrophages. PMID:27013794

  17. Inhibition of connexin 36 hemichannels by glucose contributes to the stimulation of insulin secretion.

    PubMed

    Pizarro-Delgado, Javier; Fasciani, Ilaria; Temperan, Ana; Romero, María; González-Nieto, Daniel; Alonso-Magdalena, Paloma; Nualart-Marti, Anna; Estil'les, Elisabet; Paul, David L; Martín-del-Río, Rafael; Montanya, Eduard; Solsona, Carles; Nadal, Angel; Barrio, Luis Carlos; Tamarit-Rodríguez, J

    2014-06-15

    The existence of functional connexin36 (Cx36) hemichannels in β-cells was investigated in pancreatic islets of rat and wild-type (Cx36(+/+)), monoallelic (Cx36(+/-)), and biallelic (Cx36(-/-)) knockout mice. Hemichannel opening by KCl depolarization was studied by measuring ATP release and changes of intracellular ATP (ADP). Cx36(+/+) islets lost ATP after depolarization with 70 mM KCl at 5 mM glucose; ATP loss was prevented by 8 and 20 mM glucose or 50 μM mefloquine (connexin inhibitor). ATP content was higher in Cx36(-/-) than Cx36(+/+) islets and was not decreased by KCl depolarization; Cx36(+/-) islets showed values between that of control and homozygous islets. Five minimolar extracellular ATP increased ATP content and ATP/ADP ratio and induced a biphasic insulin secretion in depolarized Cx36(+/+) and Cx36(+/-) but not Cx36(-/-) islets. Cx36 hemichannels expressed in oocytes opened upon depolarization of membrane potential, and their activation was inhibited by mefloquine and glucose (IC₅₀ ∼8 mM). It is postulated that glucose-induced inhibition of Cx36 hemichannels in islet β-cells might avoid depolarization-induced ATP loss, allowing an optimum increase of the ATP/ADP ratio by sugar metabolism and a biphasic stimulation of insulin secretion. Gradual suppression of glucose-induced insulin release in Cx36(+/-) and Cx36(-/-) islets confirms that Cx36 gap junction channels are necessary for a full secretory stimulation and might account for the glucose intolerance observed in mice with defective Cx36 expression. Mefloquine targeting of Cx36 on both gap junctions and hemichannels also suppresses glucose-stimulated secretion. By contrast, glucose stimulation of insulin secretion requires Cx36 hemichannels' closure but keeping gap junction channels opened.

  18. Coordinated regulation of esterification and lipolysis by palmitate, H2O2 and the anti-diabetic sulfonylurea drug, glimepiride, in rat adipocytes.

    PubMed

    Müller, Günter; Wied, Susanne; Straub, Julia; Jung, Christian

    2008-11-12

    Inhibition of lipolysis by palmitate, H2O2 and the anti-diabetic sulfonylurea drug, glimepiride, in isolated rat adipocytes has previously been shown to rely on the degradation of cyclic adenosine monophosphate by the phosphodiesterase, Gce1, and the 5'-nucleotidase, CD73. These glycosylphosphatidylinositol (GPI)-anchored proteins are translocated from plasma membrane lipid rafts to intracellular lipid droplets upon H2O2-induced activation of a GPI-specific phospholipase C (GPI-PLC) in response to palmitate and glimepiride in intact adipocytes and, as demonstrated here, in cell-free systems as well. The same agents are also known to stimulate the incorporation of fatty acids into triacylglycerol. Here the involvement of H2O2 production, GPI-PLC activation and translocation of Gce1 and CD73 in the agent-induced esterification and accompanying lipid droplet formation was tested in rat adipocytes using relevant inhibitors. The results demonstrate that upregulation of the esterification and accumulation of triacylglycerol by glimepiride depends on the sequential H2O2-induced GPI-PLC activation and GPI-protein translocation as does inhibition of lipolysis. In contrast, stimulation of the esterification and triacylglycerol accumulation by palmitate relies on insulin-independent tyrosine phosphorylation and thus differs from its anti-lipolytic mechanism. As expected, insulin regulates lipid metabolism via typical insulin signalling independent of H2O2 production, GPI-PLC activation and GPI-protein translocation, albeit these processes are moderately stimulated by insulin. In conclusion, triacylglycerol and lipid droplet formation in response to glimepiride and H2O2 may involve the hydrolysis of cyclic adenosine monophosphate by lipid droplet-associated Gce1 and CD73 which may regulate lipid droplet-associated triacylglycerol-synthesizing and hydrolyzing enzymes in coordinated and inverse fashion.

  19. Inhibition of Ca²⁺/calmodulin-dependent protein kinase kinase 2 stimulates osteoblast formation and inhibits osteoclast differentiation.

    PubMed

    Cary, Rachel L; Waddell, Seid; Racioppi, Luigi; Long, Fanxin; Novack, Deborah V; Voor, Michael J; Sankar, Uma

    2013-07-01

    Bone remodeling, a physiological process characterized by bone formation by osteoblasts (OBs) and resorption of preexisting bone matrix by osteoclasts (OCs), is vital for the maintenance of healthy bone tissue in adult humans. Imbalances in this vital process result in pathological conditions including osteoporosis. Owing to its initial asymptomatic nature, osteoporosis is often detected only after the patient has sustained significant bone loss or a fracture. Hence, anabolic therapeutics that stimulate bone accrual is in high clinical demand. Here we identify Ca²⁺/calmodulin (CaM)-dependent protein kinase kinase 2 (CaMKK2) as a potential target for such therapeutics because its inhibition enhances OB differentiation and bone growth and suppresses OC differentiation. Mice null for CaMKK2 possess higher trabecular bone mass in their long bones, along with significantly more OBs and fewer multinuclear OCs. In vitro, although Camkk2⁻/⁻ mesenchymal stem cells (MSCs) yield significantly higher numbers of OBs, bone marrow cells from Camkk2⁻/⁻ mice produce fewer multinuclear OCs. Acute inhibition of CaMKK2 by its selective, cell-permeable pharmacological inhibitor STO-609 also results in increased OB and diminished OC formation. Further, we find phospho-protein kinase A (PKA) and Ser¹³³ phosphorylated form of cyclic adenosine monophosphate (cAMP) response element binding protein (pCREB) to be markedly elevated in OB progenitors deficient in CaMKK2. On the other hand, genetic ablation of CaMKK2 or its pharmacological inhibition in OC progenitors results in reduced pCREB as well as significantly reduced levels of its transcriptional target, nuclear factor of activated T cells, cytoplasmic (NFATc1). Moreover, in vivo administration of STO-609 results in increased OBs and diminished OCs, conferring significant protection from ovariectomy (OVX)-induced osteoporosis in adult mice. Overall, our findings reveal a novel function for CaMKK2 in bone remodeling and

  20. [Erythropoiesis and functional characteristics in bone marrow erythroblastic islets during stimulated adn inhibited erythropoiesis].

    PubMed

    Rassokhin, A G; Kruglov, D G; Zakharov, Iu M

    2000-01-01

    When erythropiesis is stimulated (acute blood loss) or inhibited (posttransfusion polycythemia), there are early changes in the cytochemical values of erythroblastic islets (EI): in the levels of acid and neutral glucoconjugates and in the activity of nonspecific esterase. A close correlation has been found between the erythropoiesis in EI and its functional characteristics. It is concluded that central macrophages play the key role in the modulation of EI erythropoiesis. It is suggested that EI macrophages are involved in the provision of bioenergetic and reparative processes in EI.

  1. The effect of transcranial direct current stimulation: a role for cortical excitation/inhibition balance?

    PubMed Central

    Krause, Beatrix; Márquez-Ruiz, Javier; Kadosh, Roi Cohen

    2013-01-01

    Transcranial direct current stimulation (tDCS) is a promising tool for cognitive enhancement and neurorehabilitation in clinical disorders in both cognitive and clinical domains (e.g., chronic pain, tinnitus). Here we suggest the potential role of tDCS in modulating cortical excitation/inhibition (E/I) balance and thereby inducing improvements. We suggest that part of the mechanism of action of tDCS can be explained by non-invasive modulations of the E/I balance. PMID:24068995

  2. Water Soluble Single-Walled Carbon Nanotubes Inhibit Stimulated Endocytosis in Neurons

    PubMed Central

    Malarkey, Erik B.; Reyes, Reno C.; Zhao, Bin; Haddon, Robert C.; Parpura, Vladimir

    2009-01-01

    We report the use of chemically-functionalized water soluble single-walled carbon nanotube (SWNT) graft copolymers to inhibit endocytosis. The graft copolymers were prepared by the functionalization of SWNTs with poly-ethylene glycol. When added to the culturing medium, these functionalized water soluble SWNTs were able to increase the length of various neuronal processes, neurites, as previously reported. Here we have determined that SWNTs are able to block stimulated membrane endocytosis in neurons, which could then explain the previously noted extended neurite length. PMID:18759491

  3. Angiopoietin-like 4 (Angptl4) protein is a physiological mediator of intracellular lipolysis in murine adipocytes.

    PubMed

    Gray, Nora E; Lam, Lily N; Yang, Karen; Zhou, Anna Y; Koliwad, Suneil; Wang, Jen-Chywan

    2012-03-09

    Intracellular triacylglycerol (TG) hydrolysis and fatty acid release by the white adipose tissue (WAT) during a fast is stimulated by counter-regulatory factors acting in concert, although how adipocytes integrate these lipolytic inputs is unknown. We tested the role of angiopoietin-like 4 (Angptl4), a secreted protein induced by fasting or glucocorticoid treatment, in modulating intracellular adipocyte lipolysis. Glucocorticoid receptor blockade prevented fasting-induced tissue Angptl4 expression and WAT TG hydrolysis in mice, and TG hydrolysis induced by fasts of 6 or 24 h was greatly reduced in mice lacking Angptl4 (Angptl4(-/-)). Glucocorticoid treatment mimicked the lipolytic effects of fasting, although with slower kinetics, and this too required Angptl4. Thus, fasting-induced WAT TG hydrolysis requires glucocorticoid action and Angptl4. Both fasting and glucocorticoid treatment also increased WAT cAMP levels and downstream phosphorylation of lipolytic enzymes. Angptl4 deficiency markedly reduced these effects, suggesting that Angptl4 may stimulate lipolysis by modulating cAMP-dependent signaling. In support of this, cAMP levels and TG hydrolysis were reduced in primary Angptl4(-/-) murine adipocytes treated with catecholamines, which stimulate cAMP-dependent signaling to promote lipolysis, and was restored by treatment with purified human ANGPTL4. Remarkably, human ANGPTL4 treatment alone increased cAMP levels and induced lipolysis in these cells. Pharmacologic agents revealed that Angptl4 modulation of cAMP-dependent signaling occurs upstream of adenylate cyclase and downstream of receptor activation. We show that Angptl4 is a glucocorticoid-responsive mediator of fasting-induced intracellular lipolysis and stimulates cAMP signaling in adipocytes. Such a role is relevant to diseases of aberrant lipolysis, such as insulin resistance.

  4. Angiopoietin-like 4 (Angptl4) Protein Is a Physiological Mediator of Intracellular Lipolysis in Murine Adipocytes*

    PubMed Central

    Gray, Nora E.; Lam, Lily N.; Yang, Karen; Zhou, Anna Y.; Koliwad, Suneil; Wang, Jen-Chywan

    2012-01-01

    Intracellular triacylglycerol (TG) hydrolysis and fatty acid release by the white adipose tissue (WAT) during a fast is stimulated by counter-regulatory factors acting in concert, although how adipocytes integrate these lipolytic inputs is unknown. We tested the role of angiopoietin-like 4 (Angptl4), a secreted protein induced by fasting or glucocorticoid treatment, in modulating intracellular adipocyte lipolysis. Glucocorticoid receptor blockade prevented fasting-induced tissue Angptl4 expression and WAT TG hydrolysis in mice, and TG hydrolysis induced by fasts of 6 or 24 h was greatly reduced in mice lacking Angptl4 (Angptl4−/−). Glucocorticoid treatment mimicked the lipolytic effects of fasting, although with slower kinetics, and this too required Angptl4. Thus, fasting-induced WAT TG hydrolysis requires glucocorticoid action and Angptl4. Both fasting and glucocorticoid treatment also increased WAT cAMP levels and downstream phosphorylation of lipolytic enzymes. Angptl4 deficiency markedly reduced these effects, suggesting that Angptl4 may stimulate lipolysis by modulating cAMP-dependent signaling. In support of this, cAMP levels and TG hydrolysis were reduced in primary Angptl4−/− murine adipocytes treated with catecholamines, which stimulate cAMP-dependent signaling to promote lipolysis, and was restored by treatment with purified human ANGPTL4. Remarkably, human ANGPTL4 treatment alone increased cAMP levels and induced lipolysis in these cells. Pharmacologic agents revealed that Angptl4 modulation of cAMP-dependent signaling occurs upstream of adenylate cyclase and downstream of receptor activation. We show that Angptl4 is a glucocorticoid-responsive mediator of fasting-induced intracellular lipolysis and stimulates cAMP signaling in adipocytes. Such a role is relevant to diseases of aberrant lipolysis, such as insulin resistance. PMID:22267746

  5. Cyclic adenosine monophosphate acutely inhibits and chronically stimulates Na/H antiporter in OKP cells.

    PubMed Central

    Cano, A; Preisig, P; Alpern, R J

    1993-01-01

    Parathyroid hormone, dopamine, alpha-adrenergic catecholamines, and angiotensin II regulate renal Na excretion, at least in part through modulation of acute cyclic (c)AMP-induced proximal tubule Na/H antiporter inhibition. The present studies examined the effect of chronic increases in cell cAMP on Na/H antiporter activity in OKP cells. Whereas 8-bromo cAMP acutely inhibited Na/H antiporter activity, chronic application for 6 h led to a 24% increase in Na/H antiporter activity measured 16-20 h after cAMP removal. This chronic persistent activation of the Na/H antiporter required > 2 h exposure. This effect was not a nonspecific effect of 8-bromo cAMP, in that addition of forskolin or forskolin + 3-isobutyl-1-methylxanthine for 6 h also led to a chronic persistent increase in Na/H antiporter activity. Inhibition of protein synthesis with cycloheximide prevented 8-bromo cAMP-induced Na/H antiporter stimulation. Although 8-bromo cAMP addition decreased cell pH by 0.15-0.20 pH U, Na/H antiporter stimulation could be dissociated from cell acidification. In summary, while cAMP acutely inhibits Na/H antiporter activity, it chronically increases antiporter activity. This chronic activation occurs with exogenous addition or endogenous generation of cAMP. These results imply that for hormones that modulate renal Na excretion and proximal tubule Na/H antiporter activity via cAMP and protein kinase A, acute effects may not predict chronic effects. PMID:7691881

  6. Neuropeptide Y inhibits depolarization-stimulated catecholamine synthesis in rat pheochromocytoma cells.

    PubMed

    McCullough, L A; Westfall, T C

    1995-12-20

    In PC12 rat pheochromocytoma cells differentiated with nerve growth factor (NGF), neuropeptide Y inhibited depolarization-stimulated catecholamine synthesis as determined by in situ measurement of 3,4-dihydroxyphenylalanine (DOPA) production in the presence of the decarboxylase inhibitor m-hydroxybenzylhydrazine (NSD-1015). The inhibition by neuropeptide Y was concentration-dependent and was prevented by pretreatment with pertussis toxin, suggesting the involvement of a GTP-binding protein of the Gi or Go subtype. The neuropeptide Y analog [Leu31,Pro34]neuropeptide Y also caused inhibition of DOPA production, but was less potent than neuropeptide Y itself, while peptide YY and neuropeptide Y-(13-36) had no significant effect. This pattern is most consistent with the involvement of the neuropeptide Y Y3 receptor subtype. In PC12 cells differentiated with dexamethasone, neuropeptide Y also caused a concentration-dependent inhibition of DOPA production, while peptide YY was again without effect. Neuropeptide Y had no effect on DOPA production in undifferentiated PC12 cells. These results indicate that neuropeptide Y can modulate catecholamine synthesis in addition to its modulatory effects on catecholamine release.

  7. Both standing and postural threat decrease Achilles' tendon reflex inhibition from tendon electrical stimulation.

    PubMed

    Horslen, Brian C; Inglis, J Timothy; Blouin, Jean-Sébastien; Carpenter, Mark G

    2017-07-01

    Golgi tendon organs (GTOs) and associated Ib reflexes contribute to standing balance, but the potential impacts of threats to standing balance on Ib reflexes are unknown. Tendon electrical stimulation to the Achilles' tendon was used to probe changes in Ib inhibition in medial gastrocnemius with postural orientation (lying prone vs. upright standing; experiment 1) and height-induced postural threat (standing at low and high surface heights; experiment 2). Ib inhibition was reduced while participants stood upright, compared to lying prone (42.2%); and further reduced when standing in the high, compared to low, threat condition (32.4%). These experiments will impact future research because they demonstrate that tendon electrical stimulation can be used to probe Ib reflexes in muscles engaged in standing balance. These results provide novel evidence that human short-latency GTO-Ib reflexes are dependent upon both task, as evidenced by changes with postural orientation, and context, such as height-induced postural threat during standing. Golgi tendon organ Ib reflexes are thought to contribute to standing balance control, but it is unknown if they are modulated when people are exposed to a postural threat. We used a novel application of tendon electrical stimulation (TStim) to elicit Ib inhibitory reflexes in the medial gastrocnemius, while actively engaged in upright standing balance, to examine (a) how Ib reflexes to TStim are influenced by upright stance, and (b) the effects of height-induced postural threat on Ib reflexes during standing. TStim evoked short-latency (<47 ms) inhibition apparent in trigger-averaged rectified EMG, which was quantified in terms of area, duration and mean amplitude of inhibition. In order to validate the use of TStim in a standing model, TStim-Ib inhibition was compared from conditions where participants were lying prone vs. standing upright. TStim evoked Ib inhibition in both conditions; however, significant reductions in Ib

  8. Kinetics of ruminal lipolysis of triacylglycerol and biohydrogenation of long-chain fatty acids: new insights from old data.

    PubMed

    Moate, P J; Boston, R C; Jenkins, T C; Lean, I J

    2008-02-01

    Previous investigations into ruminal lipolysis of triacylglycerol and ruminal biohydrogenation (BH) of unsaturated long-chain fatty acids have generally quantified these processes with either zero-order or first-order kinetics. This investigation examined if Michaelis-Menten and other nonlinear kinetics might be useful for quantifying these processes. Data from 2 previously published in vitro experiments employing rumen fluid from sheep to investigate the lipolysis of trilinolein, the BH of cis-9, cis-12 linoleic acid (LA), and the BH of fatty acids derived from the lipolysis of trilinolein were used for the development of a multi-compartmental model. The model described the lipolysis of triacylglycerol well. The model also provided a good mathematical description of the resulting production of nonesterified fatty acids, the isomerization of nonesterified LA, and subsequent production of rumenic acid (RA), vaccenic acid (VA), and stearic acid (SA). However, the model described poorly the patterns of the concentrations of LA, RA, VA, and SA after incubation of trilinolein in rumen fluid. The model is consistent with known stoichiometry and biochemistry and is parsimonious in that it employs a minimal number of parameters to describe all of the major aspects of lipolysis and BH. The first step in the lipolysis of trilinolein was described by Michaelis-Menten kinetics (Vmax = 529 +/- 16 mg/L per h; Km = 698 +/- 41 mg/L). Both subsequent lipolysis steps were approximated by a first-order (linear kinetics) rate constant (k = 2.64 +/- 0.041 /h). Isomerization of LA to RA was modeled by simple Michaelis-Menten kinetics (Vmax = 2,421 +/- 83 mg/L per h; Km = 440 +/- 22 mg/L). The kinetics of the BH of RA to VA was described by a Michaelis-Menten-type process involving competitive inhibition by VA (Vmax = 492 +/- 6.5 mg/L per h; Km = 1 mg/L). The final step, the BH of VA to SA, was modeled by a quasi-first-order process (k = 0.533 +/- 0.021 /h), but as the concentration of

  9. Sirtuin inhibition attenuates the production of inflammatory cytokines in lipopolysaccharide-stimulated macrophages

    SciTech Connect

    Fernandes, Claudia A.; Fievez, Laurence; Neyrinck, Audrey M.; Delzenne, Nathalie M.; Bureau, Fabrice; Vanbever, Rita

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer Lipopolysaccharide-stimulated macrophages were treated with cambinol and sirtinol. Black-Right-Pointing-Pointer Cambinol and sirtinol decreased lipopolysaccharide-induced cytokines. Black-Right-Pointing-Pointer Cambinol decreased NF-{kappa}B activity but had no impact on p38 MAPK activation. Black-Right-Pointing-Pointer Sirtuins are an interesting target for the treatment of inflammatory diseases. -- Abstract: In several inflammatory conditions such as rheumatoid arthritis or sepsis, the regulatory mechanisms of inflammation are inefficient and the excessive inflammatory response leads to damage to the host. Sirtuins are class III histone deacetylases that modulate the activity of several transcription factors that are implicated in immune responses. In this study, we evaluated the impact of sirtuin inhibition on the activation of lipopolysaccharide (LPS)-stimulated J774 macrophages by assessing the production of inflammatory cytokines. The pharmacologic inhibition of sirtuins decreased the production of tumour necrosis factor-alpha (TNF-{alpha}) interleukin 6 (IL-6) and Rantes. The reduction of cytokine production was associated with decreased nuclear factor kappa B (NF-{kappa}B) activity and inhibitor kappa B alpha (I{kappa}B{alpha}) phosphorylation while no impact was observed on the phosphorylation status of p38 mitogen-activated kinase (p38 MAPK). This work shows that sirtuin pharmacologic inhibitors are a promising tool for the treatment of inflammatory conditions.

  10. Arecoline stimulated Cyr61 production in human gingival epithelial cells: inhibition by lovastatin.

    PubMed

    Deng, Yi-Ting; Chang, Jenny Zwei-Chieng; Yeh, Cheng-Chang; Cheng, Shih-Jung; Kuo, Mark Yen-Ping

    2011-04-01

    Cyr61 is associated with growth and progression of many types of tumors and is an independent poor prognostic indicator for oral cancer patients. Areca nut (AN) chewing is the most important etiological factor in the pathogenesis of oral cancer in India and many Southeast Asian countries. Yet, the molecular mechanisms involved in the AN-induced oral cancer remain largely unknown. In this study, we show that arecoline, a main alkaloid found in AN, stimulated Cyr61 synthesis in human gingival epithelial S-G cells. Constitutive overexpression of Cyr61 protein in oral epithelial cells during AN chewing may play a role in the pathogenesis of oral cancer. ERK inhibitor PD98059, N-acetyl-L-cysteine, Rho-associated protein kinase (ROCK) selective inhibitor Y-27632 and a geranylgeranyltransferase inhibitor reduced the arecoline-stimulated levels of Cyr61 protein by ∼31%, 47%, 65% and 100%, respectively. Lovastatin also completely inhibited arecoline-induced Cyr61 synthesis and the inhibition is dose-dependent. Decreased of geranylgeranylated proteins could be the mechanism that lovastatin regulates Cyr61 synthesis and lovastatin could serve as a useful agent in controlling AN-induced oral cancer. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Inhibition of Rho protein stimulates iNOS expression in rat vascular smooth muscle cells.

    PubMed

    Muniyappa, R; Xu, R; Ram, J L; Sowers, J R

    2000-06-01

    Inducible nitric oxide synthase (iNOS) in vascular smooth muscle cells (VSMCs) is upregulated in arterial injury and plays a role in regulating VSMC proliferation and restenosis. Inflammatory cytokines [e.g., interleukin-1beta (IL-1beta)] released during vascular injury induce iNOS. Small GTP-binding proteins of the Ras superfamily play a major role in IL-1beta-dependent signaling pathways. In this study, we examined the role of Rho GTPases in regulating iNOS expression in VSMCs. Treatment of VSMCs with mevastatin, which inhibits isoprenylation of Rho and other small GTP-binding proteins, produced significantly higher amounts of IL-1beta-evoked NO and iNOS protein compared with control. Similarly, bacterial toxins [Toxin B from Clostridium difficile and C3 ADP-ribosyl transferase (C3) toxin from Clostridium botulinium] that specifically inactivate Rho proteins increased NOS products (NO and citrulline) and iNOS expression. Toxin B increased the activity of iNOS promoter-reporter construct in VSMCs. Both toxins enhanced IL-1beta-stimulated iNOS expression and NO production. These data demonstrate for the first time that inhibition of Rho induces iNOS and suggest a role for Rho protein in IL-1beta-stimulated NO production in VSMCs.

  12. Inhibition of glucose oxidation by alpha-cyano-4-hydroxycinnamic acid stimulates feeding in rats.

    PubMed

    Del Prete, E; Lutz, T A; Scharrer, E

    2004-01-01

    Alpha-cyano-4-hydroxycinnamic acid (4-CIN, 100-200 mg/kg b.wt.), which impairs glucose oxidation by inhibiting pyruvate transport across the mitochondrial membrane, stimulated feeding in rats following intraperitoneal injection without affecting blood glucose level. Like 2-deoxy-D-glucose (2-DG), an inhibitor of glycolysis, 4-CIN probably acts mainly on the CNS through activation of alpha(2)-adrenergic receptors, because the feeding response to 4-CIN was eliminated by phentolamine or yohimbine. Unlike feeding elicited by 2-DG, 4-CIN-induced feeding was eliminated by total abdominal (but not hepatic branch) vagotomy. Since peripheral atropinization also blocked 4-CIN-induced feeding, activation of central parasympathetic neurons seems to be involved in 4-CIN-induced feeding. The feeding response to 4-CIN was diminished in rats fed a high-fat diet, probably because metabolic sensors sensing fatty acid oxidation counteract the feeding response to 4-CIN. The results suggest that inhibition of glucose oxidation by blocking pyruvate entry into mitochondria stimulates feeding in rats in particular when fed a high-carbohydrate diet.

  13. Vimentin Is a Functional Partner of Hormone Sensitive Lipase And Facilitates Lipolysis

    PubMed Central

    Shen, Wen-Jun; Patel, Shailja; Eriksson, John E.; Kraemer, Fredric B.

    2010-01-01

    Lipolysis involves a number of components including signaling pathways, droplet-associated proteins and lipases such as hormone-sensitive lipase (HSL). We used Surface Enhanced Laser Desorption/Ionization time-of-flight mass spectroscopy to identify cellular proteins that might interact with HSL and potentially influence lipolysis. Using recombinant HSL as bait on protein chips, clusters of proteins of 14.7 to 18.9 kDa, 25.8–26.8 kDa, 36.1 kDa, 44.3–49.1 kDa, and one at 53.7 kDa were identified that interact with HSL, particularly when lysates were examined from β-agonist treated mouse adipocytes. The ability to detect these interacting proteins was markedly diminished when the adipocytes were treated with insulin. A very similar pattern of proteins was identified when anti-HSL IgG was used as the bait. Following immunocapture, the identification of the prominent 53.7 kDa protein was carried out by tryptic digestion and MS analysis, and determined to be vimentin. The interaction of HSL with vimentin, and its hormonal dependence, was confirmed by co-immunoprecipitation. β-agonist stimulated lipolysis and the rate of HSL translocation were impaired in vimentin null adipocytes, even though normal amounts of lipases and droplet-associated proteins are expressed. The current studies provide evidence that vimentin participates in lipolysis through direct, hormonally regulated interactions with HSL. PMID:20143880

  14. Sensitivity of adipocyte lipolysis to stimulatory and inhibitory agonists in hypothyroidism and starvation.

    PubMed

    Saggerson, E D

    1986-09-01

    The responsiveness of lipolysis to the stimulatory agonists noradrenaline, corticotropin and glucagon and to the inhibitory agonists N6-phenylisopropyladenosine, prostaglandin E1 and nicotinic acid was investigated with rat white adipocytes incubated with a high concentration of adenosine deaminase (1 unit/ml). The cells were obtained from fed or 48 h-starved euthyroid animals or from fed or starved animals rendered hypothyroid by 4 weeks of treatment with low-iodine diet and propylthiouracil. Hypothyroidism increased sensitivity to and efficacy of all three inhibitory agonists in their opposition of noradrenaline-stimulated lipolysis. Starvation decreased sensitivity to all three inhibitory agonists when opposing basal lipolysis. Hypothyroidism decreased sensitivity to noradrenaline, glucagon and corticotropin by 37-, 4- and 4-fold respectively and decreased the maximum response to these agonists by approx. 50%, 50% and 75% respectively. Starvation reversed decreases in maximum response to these agonists in hypothyroidism. Starvation in the euthyroid state increased sensitivity to glucagon and noradrenaline, but did not alter sensitivity to corticotropin. Cells from hypothyroid rats were relatively insensitive to Bordetella pertussis toxin, which substantially increased basal lipolysis in the euthyroid state.

  15. Molecular Basis of ABHD5 Lipolysis Activation

    PubMed Central

    Sanders, Matthew A.; Zhang, Huamei; Mladenovic, Ljiljana; Tseng, Yan Yuan; Granneman, James G.

    2017-01-01

    Alpha-beta hydrolase domain-containing 5 (ABHD5), the defective gene in human Chanarin-Dorfman syndrome, is a highly conserved regulator of adipose triglyceride lipase (ATGL)-mediated lipolysis that plays important roles in metabolism, tumor progression, viral replication, and skin barrier formation. The structural determinants of ABHD5 lipolysis activation, however, are unknown. We performed comparative evolutionary analysis and structural modeling of ABHD5 and ABHD4, a functionally distinct paralog that diverged from ABHD5 ~500 million years ago, to identify determinants of ABHD5 lipolysis activation. Two highly conserved ABHD5 amino acids (R299 and G328) enabled ABHD4 (ABHD4 N303R/S332G) to activate ATGL in Cos7 cells, brown adipocytes, and artificial lipid droplets. The corresponding ABHD5 mutations (ABHD5 R299N and ABHD5 G328S) selectively disrupted lipolysis without affecting ATGL lipid droplet translocation or ABHD5 interactions with perilipin proteins and ABHD5 ligands, demonstrating that ABHD5 lipase activation could be dissociated from its other functions. Structural modeling placed ABHD5 R299/G328 and R303/G332 from gain-of-function ABHD4 in close proximity on the ABHD protein surface, indicating they form part of a novel functional surface required for lipase activation. These data demonstrate distinct ABHD5 functional properties and provide new insights into the functional evolution of ABHD family members and the structural basis of lipase regulation. PMID:28211464

  16. Immobilised lipase for in vitro lipolysis experiments.

    PubMed

    Phan, Stephanie; Salentinig, Stefan; Hawley, Adrian; Boyd, Ben J

    2015-04-01

    In vitro lipolysis experiments are used to assess digestion of lipid-based formulations, and probe solubilisation by colloidal phases during digestion. However, proteins and other biological components in the pancreatin often used as the lipase result in high-background scattering when interrogating structures using scattering approaches, complicating the resolution of colloidal structures. In this study, to circumvent this problem, a modified in vitro digestion model employing lipase immobilised on polymer beads, which allows for separation of the lipid digestion components during lipolysis, was investigated. Titration of the fatty acids released during digestion of medium chain triglycerides using pancreatin compared with immobilised lipase, combined with HPLC was used to follow the digestion, and small-angle X-ray scattering was used to determine colloidal structure formation. Digestion of medium chain triglycerides at the same nominal activity revealed that for the immobilised lipase, a longer digestion time was required to achieve the same extent of digestion. However, the same structural endpoint was observed, indicating that structure formation was not affected by the choice of lipase used. Lipolysis with immobilised lipase led to the reduction of parasitic scattering, resulting in clearer and more defined scattering from the structures generated by the lipolysis products. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  17. Stimulation and inhibition of gastrointestinal propulsion induced by substance P and substance K in the rat.

    PubMed Central

    Holzer, P.

    1985-01-01

    Substance P and substance K (neurokinin A) (dose range: 0.08-80 nmol kg-1) were tested for their effects on gastrointestinal propulsion in the rat. The peptides were given by intraperitoneal injection concurrently with the intragastric administration of a test meal containing charcoal and 51Cr. Examination 3 min after the test meal showed that high doses of substance P (greater than 0.74 nmol kg-1) and substance K (greater than 8.8 nmol kg-1) inhibited gastric emptying and gastrointestinal transit. This inhibitory effect was changed to a stimulant effect by pretreatment of the rats with atropine (3.5 mumol kg-1). Guanethidine pretreatment (67 mumol kg-1) revealed a facilitatory effect of low doses of the two tachykinins (about 1 nmol kg-1) on gastrointestinal propulsion. Examination 15 min after the test meal demonstrated that substance P (greater than 0.74 nmol kg-1) dose-dependently enhanced gastrointestinal propulsion, an effect that was also seen after atropine pretreatment. Low doses of substance K (about 1 nmol kg-1) also stimulated gastrointestinal propulsion but this effect was abolished by atropine. In addition, atropine pretreatment revealed a stimulant effect of high doses of substance K (88 nmol kg-1) on gastric emptying. These results show that the effects of substance P and substance K on gastrointestinal propulsion vary with dose and time and involve, at least partly, activation of the autonomic nervous system. PMID:2413940

  18. Gemifloxacin inhibits cytokine secretion by lipopolysaccharide stimulated human monocytes at the post-transcriptional level.

    PubMed

    Araujo, F; Slifer, T; Li, S; Kuver, A; Fong, L; Remington, J

    2004-03-01

    The fluroquinolone gemifloxacin was examined for its capacity to modulate secretion of cytokines by human monocytes stimulated with lipopolysaccharide (LPS). Monocytes from six male and two female healthy volunteers were stimulated with LPS, exposed to gemifloxacin and the amounts of secreted IL-1 alpha, IL-1 beta, IL-6, IL-10 and TNF-alpha measured at 3, 6 and 24 h. The results revealed that LPS alone increased secretion of each cytokine significantly. Treatment of the LPS-stimulated monocytes with gemifloxacin resulted in a significant inhibition (p < 0.01) of secretion of each of the cytokines from monocytes of the eight volunteers. Nuclear extracts of the human monocyte cell line, THP-1, were used in the electrophoretic mobility shift assay to determine whether gemifloxacin affects nuclear factor-kappa B (NF-kappa B) activation. In addition, RNA from THP-1 cells was used in Northern blots to determine whether inhibition of secretion of IL-1 beta and TNF-alpha by gemifloxacin occurred at the transcription or translation level. Whereas LPS induced a rapid increase in NF-kappa B activation, gemifloxacin alone did not. Gemifloxacin did not affect the kinetics or decrease the extent of activation. Northern blots indicated that the inhibitory activity of gemifloxacin occurred post-transcription. Thus, gemifloxacin may modulate the immune response by altering secretion of cytokines by human monocytes. Although the concentrations of gemifloxacin used were higher than those observed in the serum of human volunteers treated with the dose under clinical development, it should be taken into consideration that concentrations at tissue and intracellular levels may be considerably higher than serum concentrations.

  19. Nitric oxide synthase inhibition delays low-frequency stimulation-induced satellite cell activation in rat fast-twitch muscle.

    PubMed

    Martins, Karen J B; MacLean, Ian; Murdoch, Gordon K; Dixon, Walter T; Putman, Charles T

    2011-12-01

    This study examined the effect of nitric oxide synthase (NOS) inhibition via N(ω)-nitro-l-arginine methyl ester (l-NAME) administration on low-frequency stimulation-induced satellite cell (SC) activation in rat skeletal muscle. l-NAME only delayed stimulation-induced increases in SC activity. Also, stimulation-induced increases in hepatocyte growth factor (HGF) mRNA and protein expression were only abrogated at the mRNA level in l-NAME-treated animals. Therefore, early stimulation-induced SC activation appears to be NOS-dependent, while continued activation may involve NOS-independent HGF translational control mechanisms.

  20. Anti-inflammatory effects of catechols in lipopolysaccharide-stimulated microglia cells: inhibition of microglial neurotoxicity.

    PubMed

    Zheng, Long Tai; Ryu, Geun-Mu; Kwon, Byoung-Mog; Lee, Won-Ha; Suk, Kyoungho

    2008-06-24

    Microglial activation plays a pivotal role in the pathogenesis of neurodegenerative diseases by producing various proinflammatory cytokines and nitric oxide (NO). In the present study, the anti-inflammatory and subsequent neuroprotective effects of catechol and its derivatives including 3-methylcatechol, 4-methylcatechol, and 4-tert-butylcatechol were investigated in microglia and neuroblastoma cells in culture. The four catechol compounds showed anti-inflammatory effects with different potency. The catechols significantly decreased lipopolysaccharide (LPS)-induced NO and tumor necrosis factor (TNF)-alpha production in BV-2 microglia cells. The catechols also inhibited the expression of inducible nitric oxide synthase (iNOS) and TNF-alpha at mRNA or protein levels in the LPS-stimulated BV-2 cells. In addition, the catechols inhibited LPS-induced nuclear translocation of p65 subunit of nuclear factor (NF)-kappaB, IkappaB degradation, and phosphorylation of p38 mitogen-activated protein kinase (MAPK) in BV-2 cells. Moreover, the catechols attenuated the cytotoxicity of LPS-stimulated BV-2 microglia toward co-cultured rat B35 neuroblastoma cells. The catechols, however, did not protect B35 cells against H(2)O(2) toxicity, indicating that the compounds exerted the neuroprotective effect by inhibiting the inflammatory activation of microglia in the co-culture. The anti-inflammatory and neuroprotective properties of the catechols in cultured microglia and neuroblastoma cells suggest a therapeutic potential of these compounds for the treatment of neurodegenerative diseases that are associated with an excessive microglial activation.

  1. Inhibition of breast cancer resistance protein (ABCG2) in human myeloid dendritic cells induces potent tolerogenic functions during LPS stimulation.

    PubMed

    Jin, Jun-O; Zhang, Wei; Wong, Ka-Wing; Kwak, Minseok; van Driel, Ian R; Yu, Qing

    2014-01-01

    Breast cancer resistance protein (ABCG2), a member of the ATP-binding cassette transporters has been identified as a major determinant of multidrug resistance (MDR) in cancer cells, but ABC transporter inhibition has limited therapeutic value in vivo. In this research, we demonstrated that inhibition of efflux transporters ABCG2 induced the generation of tolerogenic DCs from human peripheral blood myeloid DCs (mDCs). ABCG2 expression was present in mDCs and was further increased by LPS stimulation. Treatment of CD1c+ mDCs with an ABCG2 inhibitor, Ko143, during LPS stimulation caused increased production of IL-10 and decreased production of pro-inflammatory cytokines and decreased expression of CD83 and CD86. Moreover, inhibition of ABCG2 in monocyte-derived DCs (MDDCs) abrogated the up-regulation of co-stimulatory molecules and production of pro-inflammatory cytokines in these cells in response to LPS. Furthermore, CD1c+ mDCs stimulated with LPS plus Ko143 inhibited the proliferation of allogeneic and superantigen-specific syngenic CD4+ T cells and promoted expansion of CD25+FOXP3+ regulatory T (Treg) cells in an IL-10-dependent fashion. These tolerogenic effects of ABCG2 inhibition could be abolished by ERK inhibition. Thus, we demonstrated that inhibition of ABCG2 in LPS-stimulated mDCs can potently induce tolerogenic potentials in these cells, providing crucial new information that could lead to development of better strategies to combat MDR cancer.

  2. Influence of intramuscular heat stimulation on modulation of nociception: complex role of central opioid receptors in descending facilitation and inhibition.

    PubMed

    You, Hao-Jun; Lei, Jing; Ye, Gang; Fan, Xiao-Li; Li, Qiang

    2014-10-01

    It has been reported that the threshold to activate 'silent' or inactive descending facilitation of nociception is lower than that of descending inhibition. Thus, the development of pain therapy to effectively drive descending inhibition alone, without the confounding influences of facilitation is a challenge. To address this issue we investigated the effects of intramuscular stimulation with a heating-needle on spinal nociception, assessed by measuring nociceptive paw withdrawal reflex in rats. Additionally, involvement of the thalamic 'nociceptive discriminators' (thalamic mediodorsal (MD) and ventromedial (VM) nuclei), and opioid-mediated mechanisms were further explored. Descending facilitation and inhibition were elicited by 46°C noxious heating-needle stimulation, and were regulated by thalamic MD and VM nuclei, respectively. In contrast, innocuous heating-needle stimulation at a temperature of 43°C elicited descending inhibition modulated by the thalamic VM nucleus alone. Microinjection of μ/δ/κ-opioid receptor antagonists β-funaltrexamine hydrochloride/naltrindole/nor-binaltorphimine, into the VM nucleus attenuated the 46°C intramuscular heating-needle stimulation-evoked descending inhibition, whereas treatment of the MD nucleus with β-funaltrexamine hydrochloride significantly decreased the descending facilitation. By contrast, descending inhibition evoked by 43°C heating-needle stimulation was only depressed by naltrindole, as opposed to μ- and κ-opioid receptor antagonists, which failed to influence descending inhibition. The present study reveals distinct roles of μ-opioid receptors in the function of thalamic MD and VM nuclei,which exert facilitatory and inhibitory actions on nociception. Furthermore, innocuous, but not noxious, intramuscular heating-needle stimulation targeting δ-opioid receptors is suggested to be a promising avenue for the effective inhibition of pain.

  3. [Transcranial magnetic stimulation (TMS), inhibition processes and attention deficit/hyperactivity disorder (ADHD) - an overview].

    PubMed

    Hoegl, Thomas; Bender, Stephan; Buchmann, Johannes; Kratz, Oliver; Moll, Gunther H; Heinrich, Hartmut

    2014-11-01

    Motor system excitability can be tested by transcranial magnetic stimulation CFMS). In this article, an overview of recent methodological developments and research findings related to attention deficit/hyperactivity disorder (ADHD) is provided. Different TMS parameters that reflect the function of interneurons in the motor cortex may represent neurophysiological markers of inhibition in ADHD, particularly the so-called intracortical inhibition. In children with a high level of hyperactivity and impulsivity, intracortical inhibition was comparably low at rest as shortly before the execution of a movement. TMS-evoked potentials can also be measured in the EEG so that investigating processes of excitability is not restricted to motor areas in future studies. The effects of methylphenidate on motor system excitability may be interpreted in the sense of a 'fine-tuning' with these mainly dopaminergic effects also depending on genetic parameters (DAT1 transporter). A differentiated view on the organization of motor control can be achieved by a combined analysis of TMS parameters and event-related potentials. Applying this bimodal approach, strong evidence for a deviant implementation of motor control in children with ADHD and probably compensatory mechanisms (with involvement of the prefrontal cortex) was obtained. These findings, which contribute to a better understanding of hyperactivity/impulsivity, inhibitory processes and motor control in ADHD as well as the mechanisms of medication, underline the relevance of TMS as a neurophysiological method in ADHD research.

  4. A transcranial magnetic stimulation study of abnormal cortical inhibition in schizophrenia.

    PubMed

    Fitzgerald, Paul B; Brown, Timothy L; Marston, Natasha A U; Oxley, Tom J; de Castella, Anthony; Daskalakis, Zafiris Jeff; Kulkarni, Jayashri

    2003-06-15

    Previous research suggests that patients with schizophrenia demonstrate deficits in a range of parameters of motor cortical and cognitive inhibition. I-wave facilitation and long-interval cortical inhibition (LICI) are two paired pulse transcranial magnetic stimulation paradigms that appear to assess aspects of cortical inhibitory function that have not previously been assessed in this patient group. Eighteen patients with schizophrenia (nine medication-free) were compared with eight control subjects. We assessed resting motor threshold (RMT) levels, LICI and I-wave facilitation. RMT levels did not differ between the three groups. There was a significant overall difference in I-wave facilitation levels. Both patient groups as compared with the control group showed increased facilitation. There were no differences between the groups in the measure of LICI. Patients with schizophrenia appear to have increased I-wave facilitation. Increased I-wave facilitation suggests deficient function of cortical inhibitory GABAergic activity. This is consistent with previous research that has found deficient cortical inhibition in patients with schizophrenia.

  5. Identification of Interferon-Stimulated Gene Proteins That Inhibit Human Parainfluenza Virus Type 3.

    PubMed

    Rabbani, M A G; Ribaudo, Michael; Guo, Ju-Tao; Barik, Sailen

    2016-12-15

    A major arm of cellular innate immunity is type I interferon (IFN), represented by IFN-α and IFN-β. Type I IFN transcriptionally induces a large number of cellular genes, collectively known as IFN-stimulated gene (ISG) proteins, which act as antivirals. The IFIT (interferon-induced proteins with tetratricopeptide repeats) family proteins constitute a major subclass of ISG proteins and are characterized by multiple tetratricopeptide repeats (TPRs). In this study, we have interrogated IFIT proteins for the ability to inhibit the growth of human parainfluenza virus type 3 (PIV3), a nonsegmented negative-strand RNA virus of the Paramyxoviridae family and a major cause of respiratory disease in children. We found that IFIT1 significantly inhibited PIV3, whereas IFIT2, IFIT3, and IFIT5 were less effective or not at all. In further screening a set of ISG proteins we discovered that several other such proteins also inhibited PIV3, including IFITM1, IDO (indoleamine 2,3-dioxygenase), PKR (protein kinase, RNA activated), and viperin (virus inhibitory protein, endoplasmic reticulum associated, interferon inducible)/Cig5. The antiviral effect of IDO, the enzyme that catalyzes the first step of tryptophan degradation, could be counteracted by tryptophan. These results advance our knowledge of diverse ISG proteins functioning as antivirals and may provide novel approaches against PIV3.

  6. Peripheral neuropeptide Y differentially influences adipogenesis and lipolysis in chicks from lines selected for low or high body weight.

    PubMed

    Liu, Lingbin; Wang, Guoqing; Xiao, Yang; Shipp, Steven L; Siegel, Paul B; Cline, Mark A; Gilbert, Elizabeth R

    2017-11-01

    Neuropeptide Y (NPY) stimulates appetite and promotes lipid deposition. We demonstrated a differential sensitivity in the food intake response to central NPY in chicks from lines selected for low (LWS) or high (HWS) body weight, but have not reported whether such differences exist in the periphery. At 5days, LWS and HWS chicks were intraperitoneally injected with 0 (vehicle), 60, or 120μg/kg BW NPY and subcutaneous adipose tissue and plasma were collected at 1, 3, 6, 12, and 24h (n=12). NPY injection increased glycerol-3-phosphate dehydrogenase (G3PDH) activity at 1 and 3h and reduced plasma non-esterified fatty acids (NEFAs) at 1 and 12h. G3PDH activity was greater in HWS than LWS while NEFAs were greater in LWS. At 1h, peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer binding protein (C/EBP)α, and microsomal triglyceride transfer protein (MTTP) mRNAs were reduced in NPY-injected chicks whereas NPY receptor 1 (NPYR1) was increased. Expression of stearoyl-CoA desaturase (SCD1) was increased by NPY at 1h in HWS but not LWS. PPARγ (3 and 6h), C/EBPβ (3h), C/EBPα (6h) and NPYR1 and 2 (24h) mRNAs were greater in NPY- than vehicle-injected chicks. At several times, adipose triglyceride lipase, MTTP, perilipin 1, NPYR1, and NPYR2 mRNAs were greater in LWS than HWS, while expression of SCD1, glycerol-3-phosphate acyltransferase 3 and lipoprotein lipase was greater in HWS than LWS. Thus, NPY promotes fat deposition and inhibits lipolysis in chicks, with line differences indicative of greater rates of lipolysis in LWS and adipogenesis in HWS. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Suberization: inhibition by washing and stimulation by abscisic Acid in potato disks and tissue culture.

    PubMed

    Soliday, C L; Dean, B B; Kolattukudy, P E

    1978-02-01

    Wounding of potato (Solanum tuberosum L.) tubers results in suberization, apparently triggered by the release of some chemical factor(s) at the cut surface. Suberization, as measured by diffusion resistance of the tissue surface to water vapor, was inhibited by mm concentrations of indoleacetic acid, unaffected by mm concentrations of traumatic acid, severely inhibited at mum concentrations of cytokinin, but stimulated by abscisic acid (ABA) at 10(-4)m. Thorough washing of potato disks up to 3 to 4 days after cutting resulted in severe inhibition of suberization as measured both by diffusion resistance and by the amount of the octadecene diol generated by hydrogenolysis (LiAlH(4)) of the tissue. Disks washed after 4 days did not show any inhibition of suberization. High performance liquid chromatographic analysis of the wash from fresh potato disks showed that about 14 ng of ABA was released into the wash per g of tissue. The amount of ABA released increased with time up to 4 to 6 hours of washing. The maximal amount of ABA was washed out after aging for 24 hours and after 2 days of aging ABA could no longer be found in the surface wash of the disks. Addition of ABA to the media of potato tissue cultures resulted in suberin formation whereas control cultures contained little suberin. The effect of ABA on suberization in the tissue cultures was shown to be linearly concentration-dependent up to 10(-4)m and a linear increase in suberin formation was seen up to about 8 days of culture growth on the media containing 10(-4)m ABA. From these results it is proposed that during the early phase of wound-healing ABA plays a role in triggering a chain of biochemical processes which eventually (in about 3 to 4 days) result in the formation of a suberization-inducing factor, responsible for the induction of the enzymes involved in suberin biosynthesis.

  8. Reduced lipolysis response to adipose afferent reflex involved in impaired activation of adrenoceptor-cAMP-PKA-hormone sensitive lipase pathway in obesity

    PubMed Central

    Ding, Lei; Zhang, Feng; Zhao, Ming-Xia; Ren, Xing-Sheng; Chen, Qi; Li, Yue-Hua; Kang, Yu-Ming; Zhu, Guo-Qing

    2016-01-01

    Chemical stimulation of white adipose tissue (WAT) causes adipose afferent reflex (AAR) and sympathetic activation. This study is to investigate the effects of AAR on lipolysis and the mechanisms of attenuated lipolysis response to enhanced AAR in obesity. Obesity was caused by high-fat diet for 12 weeks in rats. AAR was induced by injection of capsaicin into inguinal WAT or electrical stimulation of epididymal WAT afferent nerve. AAR caused sympathetic activation, which was enhanced in obesity rats. AAR increased cAMP levels and PKA activity, promoted hormone sensitive lipase (HSL) and perilipin phosphorylation, and increased lipolysis in WAT, which were attenuated in obesity rats. PKA activity, cAMP, perilipin and β-adrenoceptor levels were reduced, while HSL was upregulated in adipocytes from obesity rats. In primary adipocytes, isoproterenol increased cAMP levels and PKA activity, promoted HSL and perilipin phosphorylation, and increased lipolysis, which were attenuated in obesity rats. The attenuated effects of isoproterenol in adipocytes from obesity rats were prevented by a cAMP analogue dbcAMP. The results indicate that reduced lipolysis response to enhanced AAR in obesity is attributed to the impaired activation of β-adrenoceptor-cAMP-PKA-HSL pathway. Increased cAMP level in adipocytes rectifies the attenuated lipolysis in obesity. PMID:27694818

  9. Reduced lipolysis response to adipose afferent reflex involved in impaired activation of adrenoceptor-cAMP-PKA-hormone sensitive lipase pathway in obesity.

    PubMed

    Ding, Lei; Zhang, Feng; Zhao, Ming-Xia; Ren, Xing-Sheng; Chen, Qi; Li, Yue-Hua; Kang, Yu-Ming; Zhu, Guo-Qing

    2016-10-03

    Chemical stimulation of white adipose tissue (WAT) causes adipose afferent reflex (AAR) and sympathetic activation. This study is to investigate the effects of AAR on lipolysis and the mechanisms of attenuated lipolysis response to enhanced AAR in obesity. Obesity was caused by high-fat diet for 12 weeks in rats. AAR was induced by injection of capsaicin into inguinal WAT or electrical stimulation of epididymal WAT afferent nerve. AAR caused sympathetic activation, which was enhanced in obesity rats. AAR increased cAMP levels and PKA activity, promoted hormone sensitive lipase (HSL) and perilipin phosphorylation, and increased lipolysis in WAT, which were attenuated in obesity rats. PKA activity, cAMP, perilipin and β-adrenoceptor levels were reduced, while HSL was upregulated in adipocytes from obesity rats. In primary adipocytes, isoproterenol increased cAMP levels and PKA activity, promoted HSL and perilipin phosphorylation, and increased lipolysis, which were attenuated in obesity rats. The attenuated effects of isoproterenol in adipocytes from obesity rats were prevented by a cAMP analogue dbcAMP. The results indicate that reduced lipolysis response to enhanced AAR in obesity is attributed to the impaired activation of β-adrenoceptor-cAMP-PKA-HSL pathway. Increased cAMP level in adipocytes rectifies the attenuated lipolysis in obesity.

  10. Hormonal regulation of intracellular lipolysis in C57BL/6J mice: effect of diet-induced adiposity and data normalization.

    PubMed

    Bederman, Ilya R; Previs, Stephen F

    2008-10-01

    The breakdown of intracellular triglycerides in adipose tissue provides fatty acids and glycerol as substrates for oxidation. However, the exposure of target organs to excess free fatty acids is associated with the development of insulin resistance and impaired regulation of carbohydrate metabolism, suggesting that the control of triglyceride breakdown is an important factor in balancing health and disease. We have studied the temporal influence of diet-induced changes in adiposity on the response of intracellular lipolysis to epinephrine +/- insulin using freshly isolated adipocytes from C57BL/6J mice fed a low-fat (10% kcal) or high-fat (HF, 45% kcal) diet for 1, 4, or 12 weeks. In this model, we also tested how data normalization affects the interpretation. The contribution of the epididymal fat to total body mass increased by approximately 15%, 45%, and 100% after 1, 4, and 12 weeks of HF diet consumption, respectively. In addition, HF feeding led to an increase in fasting insulin, that is, approximately 2-fold greater in HF- vs low-fat-fed mice at 4 and 12 weeks. We found that diet-induced changes in adiposity did not alter the lipolytic response to epinephrine when data were normalized per DNA (ie, per cell); however, the lipolytic potential of the organ (ie, the lipolytic rate per cell multiplied by the total number of cells) was increased in isolated adipocytes after 4 and 12 weeks of HF feeding. We also observed a marked impairment in insulin-mediated inhibition of epinephrine-stimulated lipolysis after 4 and 12 weeks of HF feeding, demonstrating that diet-induced adiposity leads to insulin resistance in adipocytes. In conclusion, HF feeding in mice leads to greater rates of lipolysis via (1) an increase in the number of fat cells and (2) a defect in insulin signaling in adipocytes. The combination of these 2 alterations on the control of intracellular lipolysis suggests a mechanism(s) that (partly) explains how target organs could be exposed to excess

  11. Calcium supplementation does not alter lipid oxidation or lipolysis in overweight/obese women.

    PubMed

    Sampath, Vanitha; Havel, Peter J; King, Janet C

    2008-11-01

    Based on cell culture and studies in mice, increased dietary calcium appears to stimulate lipolysis and could possibly reduce body adiposity through hormonal influences on adipocyte calcium uptake. In this study, we investigated the effects of 1,500 mg supplemental calcium daily for 3 months on hormones regulating calcium and energy metabolism and rates of lipid oxidation and lipolysis in overweight women. Fifteen overweight (BMI > 25 kg/m(2)) premenopausal women were supplemented with 1,500 mg of calcium, as CaCO(3), per day for 3 months while maintaining their usual diets and activity levels. Baseline and endpoint measurements were obtained after the subjects consumed a standardized 25% fat diet for 4 days. Lipid oxidation was measured by indirect calorimetry, lipolysis by infusion of deuterated glycerol, and body fat by dual-energy X-ray absorptiometry. Urinary calcium, circulating levels of hormones involved in energy and lipid metabolism (insulin, leptin, and adiponectin) or calcium metabolism (25(OH)D, 1,25(OH)(2)D), and parathyroid hormone (PTH)) were also measured. Urinary levels of calcium (P = 0.005) increased and 1,25(OH)(2)D declined (P = 0.03). However other parameters, including body weight, body fat, PTH, insulin, leptin, adiponectin, 25(OH)D, as well as rates of lipid oxidation and lipolysis were not altered by calcium supplementation. Calcium supplementation for 3 months increased urinary calcium excretion, decreased circulating levels of 1,25(OH)(2)-D, but had no effect on rates of lipid oxidation or lipolysis, in these overweight women.

  12. Effects of bacterial communities on biofuel-producing microalgae: stimulation, inhibition and harvesting.

    PubMed

    Wang, Hui; Hill, Russell T; Zheng, Tianling; Hu, Xiaoke; Wang, Bin

    2016-01-01

    Despite the great interest in microalgae as a potential source of biofuel to substitute for fossil fuels, little information is available on the effects of bacterial symbionts in mass algal cultivation systems. The bacterial communities associated with microalgae are a crucial factor in the process of microalgal biomass and lipid production and may stimulate or inhibit growth of biofuel-producing microalgae. In addition, we discuss here the potential use of bacteria to harvest biofuel-producing microalgae. We propose that aggregation of microalgae by bacteria to achieve >90% reductions in volume followed by centrifugation could be an economic approach for harvesting of biofuel-producing microalgae. Our aims in this review are to promote understanding of the effects of bacterial communities on microalgae and draw attention to the importance of this topic in the microalgal biofuel field.

  13. Enkephalin inhibition of angiotensin-stimulated release of oxytocin and vasopressin

    NASA Technical Reports Server (NTRS)

    Keil, L. C.; Chee, O.; Rosella-Dampman, L. M.; Emmert, S.; Summy-Long, J. Y.

    1984-01-01

    The effect of intracerebroventricular (ICV) pretreatment with 100 ng/5 microliter leucine(5)-enkephalin (LE) on the increase in plasma oxytocin (OT) and vasopressin (VP) caused by ICV injection of 10, 50, or 100 ng/5 microliter of angiotensin II (AII) is investigated experimentally in conscious adult male Sprague-Dawley rats; the effects of water-deprivation dehydration and lactation/suckling (in female rats) are also studied. An OT radioimmunoassay (RIA) with a sensitivity of 800 fg/ml (described in detail) and the VP RIA technique of Keil and Severs (1977) are employed. Administration of AII or dehydration for 48 or 72 h cause a significant increase in OT and VP without affecting the ratio, while lactation and suckling increase OT only. LE pretreatment inhibits significantly but does not suppress the AII-stimulated OT-VP response.

  14. GDF11 decreases bone mass by stimulating osteoclastogenesis and inhibiting osteoblast differentiation

    PubMed Central

    Liu, Weiqing; Zhou, Liyan; Zhou, Chenchen; Zhang, Shiwen; Jing, Junjun; Xie, Liang; Sun, Ningyuan; Duan, Xiaobo; Jing, Wei; Liang, Xing; Zhao, Hu; Ye, Ling; Chen, Qianming; Yuan, Quan

    2016-01-01

    Osteoporosis is an age-related disease that affects millions of people. Growth differentiation factor 11 (GDF11) is a secreted member of the transforming growth factor beta (TGF-β) superfamily. Deletion of Gdf11 has been shown to result in a skeletal anterior–posterior patterning disorder. Here we show a role for GDF11 in bone remodelling. GDF11 treatment leads to bone loss in both young and aged mice. GDF11 inhibits osteoblast differentiation and also stimulates RANKL-induced osteoclastogenesis through Smad2/3 and c-Fos-dependent induction of Nfatc1. Injection of GDF11 impairs bone regeneration in mice and blocking GDF11 function prevents oestrogen-deficiency-induced bone loss and ameliorates age-related osteoporosis. Our data demonstrate that GDF11 is a previously unrecognized regulator of bone remodelling and suggest that GDF11 is a potential target for treatment of osteoporosis. PMID:27653144

  15. Enkephalin inhibition of angiotensin-stimulated release of oxytocin and vasopressin

    NASA Technical Reports Server (NTRS)

    Keil, L. C.; Chee, O.; Rosella-Dampman, L. M.; Emmert, S.; Summy-Long, J. Y.

    1984-01-01

    The effect of intracerebroventricular (ICV) pretreatment with 100 ng/5 microliter leucine(5)-enkephalin (LE) on the increase in plasma oxytocin (OT) and vasopressin (VP) caused by ICV injection of 10, 50, or 100 ng/5 microliter of angiotensin II (AII) is investigated experimentally in conscious adult male Sprague-Dawley rats; the effects of water-deprivation dehydration and lactation/suckling (in female rats) are also studied. An OT radioimmunoassay (RIA) with a sensitivity of 800 fg/ml (described in detail) and the VP RIA technique of Keil and Severs (1977) are employed. Administration of AII or dehydration for 48 or 72 h cause a significant increase in OT and VP without affecting the ratio, while lactation and suckling increase OT only. LE pretreatment inhibits significantly but does not suppress the AII-stimulated OT-VP response.

  16. Palmitic acid acutely inhibits acetylcholine- but not GLP-1-stimulated insulin secretion in mouse pancreatic islets

    PubMed Central

    Qin, Wei; Vinogradov, Sergei A.; Wilson, David F.; Matschinsky, Franz M.

    2010-01-01

    Fatty acids, acetylcholine, and GLP-1 enhance insulin secretion in a glucose-dependent manner. However, the interplay between glucose, fatty acids, and the neuroendocrine regulators of insulin secretion is not well understood. Therefore, we studied the acute effects of PA (alone or in combination with glucose, acetylcholine, or GLP-1) on isolated cultured mouse islets. Two different sets of experiments were designed. In one, a fixed concentration of 0.5 mM of PA bound to 0.15 mM BSA was used; in the other, a PA ramp from 0 to 0.5 mM was applied at a fixed albumin concentration of 0.15 mM so that the molar PA/BSA ratio changed within the physiological range. At a fixed concentration of 0.5 mM, PA markedly inhibited acetylcholine-stimulated insulin release, the rise of intracellular Ca2+, and enhancement of cAMP production but did not influence the effects of GLP-1 on these parameters of islet cell function. 2-ADB, an IP3 receptor inhibitor, reduced the effect of acetylcholine on insulin secretion and reversed the effect of PA on acetylcholine-stimulated insulin release. Islet perfusion for 35–40 min with 0.5 mM PA significantly reduced the calcium storage capacity of ER measured by the thapsigargin-induced Ca2+ release. Oxygen consumption due to low but not high glucose was reduced by PA. When a PA ramp from 0 to 0.5 mM was applied in the presence of 8 mM glucose, PA at concentrations as low as 50 μM significantly augmented glucose-stimulated insulin release and markedly reduced acetylcholine's effects on hormone secretion. We thus demonstrate that PA acutely reduces the total oxygen consumption response to glucose, glucose-dependent acetylcholine stimulation of insulin release, Ca2+, and cAMP metabolism, whereas GLP-1's actions on these parameters remain unaffected or potentiated. We speculate that acute emptying of the ER calcium by PA results in decreased glucose stimulation of respiration and acetylcholine potentiation of insulin secretion. PMID:20606076

  17. Interhemispheric Inhibition Induced by Transcranial Magnetic Stimulation Over Primary Sensory Cortex

    PubMed Central

    Iwata, Yasuyuki; Jono, Yasutomo; Mizusawa, Hiroki; Kinoshita, Atsushi; Hiraoka, Koichi

    2016-01-01

    The present study investigated whether the long-interval interhemispheric inhibition (LIHI) is induced by the transcranial magnetic stimulation over the primary sensory area (S1-TMS) without activation of the conditioning side of the primary motor area (M1) contributing to the contralateral motor evoked potential (MEP), whether the S1-TMS-induced LIHI is dependent on the status of the S1 modulated by the tactile input, and whether the pathways mediating the LIHI are different from those mediating the M1-TMS-induced LIHI. In order to give the TMS over the S1 without eliciting the MEP, the intensity of the S1-TMS was adjusted to be the sub-motor-threshold level and the trials with the MEP response elicited by the S1-TMS were discarded online. The LIHI was induced by the S1-TMS given 40 ms before the test TMS in the participants with the attenuation of the tactile perception of the digit stimulation (TPDS) induced by the S1-TMS, indicating that the LIHI is induced by the S1-TMS without activation of the conditioning side of the M1 contributing to the contralateral MEP in the participants in which the pathways mediating the TPDS is sensitive to the S1-TMS. The S1-TMS-induced LIHI was positively correlated with the attenuation of the TPDS induced by the S1-TMS, indicating that the S1-TMS-induced LIHI is dependent on the effect of the S1-TMS on the pathways mediating the TPDS at the S1. In another experiment, the effect of the digit stimulation given before the conditioning TMS on the S1- or M1-TMS-induced LIHI was examined. The digit stimulation produces tactile input to the S1 causing change in the status of the S1. The S1-TMS-induced LIHI was enhanced when the S1-TMS was given in the period in which the tactile afferent volley produced by the digit stimulation just arrived at the S1, while the LIHI induced by above-motor-threshold TMS over the contralateral M1 was not enhanced by the tactile input. Thus, the S1-TMS-induced LIHI is dependent on the status of the S1

  18. Orexin A stimulates glucose uptake, lipid accumulation and adiponectin secretion from 3T3-L1 adipocytes and isolated primary rat adipocytes.

    PubMed

    Skrzypski, M; T Le, T; Kaczmarek, P; Pruszynska-Oszmalek, E; Pietrzak, P; Szczepankiewicz, D; Kolodziejski, P A; Sassek, M; Arafat, A; Wiedenmann, B; Nowak, K W; Strowski, M Z

    2011-07-01

    Orexin A (OXA) modulates body weight, food intake and energy expenditure. In vitro, OXA increases PPARγ (also known as PPARG) expression and inhibits lipolysis, suggesting direct regulation of lipid metabolism. Here, we characterise the metabolic effects and mechanisms of OXA action in adipocytes. Isolated rat adipocytes and differentiated murine 3T3-L1 adipocytes were exposed to OXA in the presence or absence of phosphoinositide 3-kinase (PI3K) inhibitors. Pparγ expression was silenced using small interfering RNA. Glucose uptake, GLUT4 translocation, phosphatidylinositol (3,4,5)-trisphosphate production, lipogenesis, lipolysis, and adiponectin secretion were measured. Adiponectin plasma levels were determined in rats treated with OXA for 4 weeks. OXA PI3K-dependently stimulated active glucose uptake by translocating the glucose transporter GLUT4 from cytoplasm into the plasma membrane. OXA increased cellular triacylglycerol content via PI3K. Cellular triacylglycerol accumulation resulted from increased lipogenesis as well as from a decrease of lipolysis. Adiponectin levels in chow- and high-fat diet-fed rats treated chronically with OXA were increased. OXA stimulated adiponectin expression and secretion in adipocytes. Both pharmacological blockade of peroxisome proliferator-activated receptor γ (PPARγ) activity or silencing Pparγ expression prevented OXA from stimulating triacylglycerol accumulation and adiponectin production. Our study demonstrates that OXA stimulates glucose uptake in adipocytes and that the evolved energy is stored as lipids. OXA increases lipogenesis, inhibits lipolysis and stimulates the secretion of adiponectin. These effects are conferred via PI3K and PPARγ2. Overall, OXA's effects on lipids and adiponectin secretion resemble that of insulin sensitisers, suggesting a potential relevance of this peptide in metabolic disorders.

  19. Src Kinase Inhibition Attenuates Morphine Tolerance without Affecting Reinforcement or Psychomotor Stimulation.

    PubMed

    Bull, Fiona A; Baptista-Hon, Daniel T; Sneddon, Claire; Wright, Lisa; Walwyn, Wendy; Hales, Tim G

    2017-08-18

    Prolonged opioid administration leads to tolerance characterized by reduced analgesic potency. Pain management is additionally compromised by the hedonic effects of opioids, the cause of their misuse. The multifunctional protein β-arrestin2 regulates the hedonic effects of morphine and participates in tolerance. These actions might reflect µ opioid receptor up-regulation through reduced endocytosis. β-Arrestin2 also recruits kinases to µ receptors. We explored the role of Src kinase in morphine analgesic tolerance, locomotor stimulation, and reinforcement in C57BL/6 mice. Analgesic (tail withdrawal latency; percentage of maximum possible effect, n = 8 to 16), locomotor (distance traveled, n = 7 to 8), and reinforcing (conditioned place preference, n = 7 to 8) effects of morphine were compared in wild-type, µ, µ, and β-arrestin2 mice. The influence of c-Src inhibitors dasatinib (n = 8) and PP2 (n = 12) was examined. Analgesia in morphine-treated wild-type mice exhibited tolerance, declining by day 10 to a median of 62% maximum possible effect (interquartile range, 29 to 92%). Tolerance was absent from mice receiving dasatinib. Tolerance was enhanced in µ mice (34% maximum possible effect; interquartile range, 5 to 52% on day 5); dasatinib attenuated tolerance (100% maximum possible effect; interquartile range, 68 to 100%), as did PP2 (91% maximum possible effect; interquartile range, 78 to 100%). By contrast, c-Src inhibition affected neither morphine-evoked locomotor stimulation nor reinforcement. Remarkably, dasatinib not only attenuated tolerance but also reversed established tolerance in µ mice. The ability of c-Src inhibitors to inhibit tolerance, thereby restoring analgesia, without altering the hedonic effect of morphine, makes c-Src inhibitors promising candidates as adjuncts to opioid analgesics.

  20. Bifunctional bioceramics stimulating osteogenic differentiation of a gingival fibroblast and inhibiting plaque biofilm formation.

    PubMed

    Shen, Ya; Wang, Zhejun; Wang, Jiao; Zhou, Yinghong; Chen, Hui; Wu, Chengtie; Haapasalo, Markus

    2016-04-01

    Gingival recession is a common clinical problem that results in esthetic deficiencies and poor plaque control and predominantly occurs in aged patients. In order to restore the cervical region, ideal biomaterials should possess the ability to stimulate proliferation and osteogenesis/cementogenesis of human gingival fibroblasts (HGF) and have a strong antibiofilm effect. The aim of the present study was to investigate the interactions of HGF and oral multispecies biofilms with Ca, Mg and Si-containing bredigite (BRT, Ca7MgSi4O16) bioceramics. BRT extract induced osteogenic/cementogenic differentiation of HGF and its inhibition of plaque biofilm formation were systematically studied. BRT extract in concentrations lower than <200 mg mL(-1) presented high biocompatibility to HGF cells in 3 days. Ion extracts from BRT also stimulated a series of bone-related gene and protein expressions in HGF cells. Furthermore, BRT extract significantly inhibited oral multispecies plaque biofilm growth on its surface and contributed to over 30% bacterial cell death without additional antibacterial agents in two weeks. A planktonic killing test showed that BRT suppressed 98% plaque bacterial growth compared to blank control in 3 days. The results also revealed that BRT extract has an osteostimulation effect on HGF. The suppression effect on plaque biofilms suggested that BRT might be used as a bioactive material for cervical restoration and that the synergistic effect of bioactive ions, such as Ca, Mg and Si ions, played an important role in the design and construction of bifunctional biomaterials in combination with tissue regeneration and antibiofilm activity.

  1. Histophilus somni Stimulates Expression of Antiviral Proteins and Inhibits BRSV Replication in Bovine Respiratory Epithelial Cells

    PubMed Central

    Lin, C.; Agnes, J. T.; Behrens, N.; Tagawa, Y.; Gershwin, L. J.; Corbeil, L. B.

    2016-01-01

    Our previous studies showed that bovine respiratory syncytial virus (BRSV) followed by Histophilus somni causes more severe bovine respiratory disease and a more permeable alveolar barrier in vitro than either agent alone. However, microarray analysis revealed the treatment of bovine alveolar type 2 (BAT2) epithelial cells with H. somni concentrated culture supernatant (CCS) stimulated up-regulation of four antiviral protein genes as compared with BRSV infection or dual treatment. This suggested that inhibition of viral infection, rather than synergy, may occur if the bacterial infection occurred before the viral infection. Viperin (or radical S-adenosyl methionine domain containing 2—RSAD2) and ISG15 (IFN-stimulated gene 15—ubiquitin-like modifier) were most up-regulated. CCS dose and time course for up-regulation of viperin protein levels were determined in treated bovine turbinate (BT) upper respiratory cells and BAT2 lower respiratory cells by Western blotting. Treatment of BAT2 cells with H. somni culture supernatant before BRSV infection dramatically reduced viral replication as determined by qRT PCR, supporting the hypothesis that the bacterial infection may inhibit viral infection. Studies of the role of the two known H. somni cytotoxins showed that viperin protein expression was induced by endotoxin (lipooligosaccharide) but not by IbpA, which mediates alveolar permeability and H. somni invasion. A naturally occurring IbpA negative asymptomatic carrier strain of H. somni (129Pt) does not cause BAT2 cell retraction or permeability of alveolar cell monolayers, so lacks virulence in vitro. To investigate initial steps of pathogenesis, we showed that strain 129Pt attached to BT cells and induced a strong viperin response in vitro. Thus colonization of the bovine upper respiratory tract with an asymptomatic carrier strain lacking virulence may decrease viral infection and the subsequent enhancement of bacterial respiratory infection in vivo. PMID:26859677

  2. Transcutaneous electrical nerve stimulation reduces pain, fatigue and hyperalgesia while restoring central inhibition in primary fibromyalgia.

    PubMed

    Dailey, Dana L; Rakel, Barbara A; Vance, Carol G T; Liebano, Richard E; Amrit, Anand S; Bush, Heather M; Lee, Kyoung S; Lee, Jennifer E; Sluka, Kathleen A

    2013-11-01

    Because transcutaneous electrical nerve stimulation (TENS) works by reducing central excitability and activating central inhibition pathways, we tested the hypothesis that TENS would reduce pain and fatigue and improve function and hyperalgesia in people with fibromyalgia who have enhanced central excitability and reduced inhibition. The current study used a double-blinded randomized, placebo-controlled cross-over design to test the effects of a single treatment of TENS with people with fibromyalgia. Three treatments were assessed in random order: active TENS, placebo TENS and no TENS. The following measures were assessed before and after each TENS treatment: pain and fatigue at rest and in movement; pressure pain thresholds, 6-m walk test, range of motion; 5-time sit-to-stand test, and single-leg stance. Conditioned pain modulation was completed at the end of testing. There was a significant decrease in pain and fatigue with movement for active TENS compared to placebo and no TENS. Pressure pain thresholds increased at the site of TENS (spine) and outside the site of TENS (leg) when compared to placebo TENS or no TENS. During active TENS, conditioned pain modulation was significantly stronger compared to placebo TENS and no TENS. No changes in functional tasks were observed with TENS. Thus, the current study suggests TENS has short-term efficacy in relieving symptoms of fibromyalgia while the stimulator is active. Future clinical trials should examine the effects of repeated daily delivery of TENS, similar to the way in which TENS is used clinically on pain, fatigue, function, and quality of life in individuals with fibromyalgia.

  3. Inhibition of stimulated dopamine release and hemodynamic response in the brain through electrical stimulation of rat forepaw.

    PubMed Central

    Chen, Y Iris; Ren, Jiaqian; Wang, Fu-Nien; Xu, Haibo; Mandeville, Joseph B; Kim, Young; Rosen, Bruce R; Jenkins, Bruce G; Hui, Kathleen KS; Kwong, Kenneth K

    2008-01-01

    The subcortical response to peripheral somatosensory stimulation is not well studied. Prior literature suggests that somatosensory stimulation can affect dopaminergic tone. We studied the effects of electrical stimulation near the median nerve on the response to an amphetamine induced increase in synaptic dopamine. We applied the electrical stimulation close to the median nerve 20 minutes after administration of 3mg/kg amphetamine. We used fMRI and microdialysis to measure markers of DA release, together with the release of associated neurotransmitters of striatal Glutamate (Glu) and GABA. Result 1) Changes in cerebral blood volume (CBV), a marker used in fMRI, indicate that electrical stimulation significantly attenuated increased DA release (due to AMPH) in the striatum, thalamus, medial prefrontal and cingulate cortices. 2) Microdialysis showed that electrical stimulation increased Glu and GABA release and attenuated the AMPH-enhanced DA release. The striatal DA dynamics correlated with the CBV response. Conclusion These results demonstrate that electrical stimulation near the median nerve activates Glu/GABA release which subsequently attenuate excess striatal DA release. These data provide evidence for physiologic modulation caused by electroacupuncture at points near the median nerve. PMID:18178315

  4. Sesamin inhibits IL-1β-stimulated inflammatory response in human osteoarthritis chondrocytes by activating Nrf2 signaling pathway.

    PubMed

    Kong, Pengyu; Chen, Guanghua; Jiang, Anlong; Wang, Yufu; Song, Chengchao; Zhuang, Jinpeng; Xi, Chunyang; Wang, Guangxi; Ji, Ye; Yan, Jinglong

    2016-12-13

    Sesamin, a bioactive component extracted from sesame, has been reported to exert anti-inflammatory and anti-oxidant effects. In this study, we evaluated the anti-inflammatory effects of sesamin on IL-1β-stimulated human osteoarthritis chondrocytes and investigated the possible mechanism. Results demonstrated that sesamin treatment significantly inhibited PGE2 and NO production induced by IL-1β. Sesamin inhibited MMP1, MMP3, and MMP13 production in IL-1β-stimulated chondrocytes. Sesamin also inhibited IL-1β-induced phosphorylation of NF-κB p65 and IκBα. Meanwhile, sesamin was found to up-regulate the expression of Nrf2 and HO-1. However, Nrf2 siRNA reversed the anti-inflammatory effects of sesamin. In conclusion, our results suggested that sesamin showed anti-inflammatory effects in IL-1β-stimulated chondrocytes by activating Nrf2 signaling pathway.

  5. Amphetamine decreases behavioral inhibition by stimulation of dopamine D2, but not D3, receptors.

    PubMed

    van Gaalen, Marcel M; Unger, Liliane; Jongen-Rêlo, Ana-Lucia; Schoemaker, Hans; Gross, Gerhard

    2009-09-01

    Behavioral disinhibition is a manifestation of impulsive behavior that is prominent in the psychopathology of various psychiatric disorders such as addiction, attention-deficit hyperactivity disorder, mania, and personality disorders. Impulsivity may be studied by measuring anticipatory responses made before the presentation of a food-predictive, brief light stimulus in a two-choice serial reaction time task. In such serial reaction time tasks, amphetamine has been shown to produce dose-dependent increases in premature responding in a manner dependent on dopamine D(2)-like receptor stimulation. So far, it is unknown whether it is the D(2) or D(3) receptor that is involved in this form of impulsivity. In this study, rats were trained in a two-choice serial reaction time task until baseline performance was stable. Next, effects of the dopamine D(2) preferring antagonist L-741,626 and selective D(3) antagonist SB-277011 were assessed alone and in the presence of amphetamine. Neither L-741,626 nor SB-277011 affected behavioral inhibition, although the latter significantly increased reaction time at 10 mg/kg. Amphetamine dose-dependently increased impulsivity. The effect of amphetamine was attenuated by L-741,626 (3 mg/kg), whereas SB-277011 (3 mg/kg) had no effect. Therefore, amphetamine-induced behavioral disinhibition depends on D(2), but not D(3), receptor stimulation.

  6. Proliferation of smooth muscle cells stimulated by Porphyromonas gingivalis is inhibited by apple polyphenol.

    PubMed

    Inaba, Hiroaki; Tagashira, Motoyuki; Kanda, Tomomasa; Amano, Atsuo

    2011-11-01

    Porphyromonas gingivalis (Pg) is thought to be involved in the progression of occlusive arterial lesions, whereas vascular smooth muscle cell (SMC) proliferation is considered to be involved in occlusive arterial disease. We previously showed that bacteremia caused by Pg infection induced proliferation of mouse aortic SMCs. Furthermore, human SMCs stimulated with human plasma incubated with Pg showed a marked transformation from the contractile to proliferative phenotype. In the present study, we examine the involvement of Pg gingipains and fimbriae in induction of the SMC transformation and proliferation, and effective inhibitors. Pg strains including gingipain- and fimbria-null mutants were incubated in human plasma, after which the bacteria were removed and the supernatants were added to cultured SMCs. To evaluate the effects of inhibitors, Pg organisms were incubated in plasma in the presence of apple polyphenol (AP), epigallocatechin gallate, KYT-1 (Arg-gingipain inhibitor), and KYT-36 (Lys-gingipain inhibitor). Plasma supernatants from wild-type and fimbria-mutant cultures markedly stimulated cellular proliferation, whereas those containing gingipain-null mutants showed negligible effects. SMC proliferation was also induced by plasma treated with trypsin. Furthermore, plasma supernatants cultured in the presence of KYT-1/KYT-36 and AP showed significant inhibitory effects on SMC proliferation, whereas cultures with epigallocatechin gallate did not. Our results suggest that Pg gingipains are involved in the induction of SMC transformation and proliferation, whereas this was inhibited by AP.

  7. Nicotinic acetylcholine receptor alpha 7 stimulation dampens splenic myelopoiesis and inhibits atherogenesis in Apoe(-/-) mice.

    PubMed

    Al-Sharea, Annas; Lee, Man K S; Whillas, Alexandra; Flynn, Michelle C; Chin-Dusting, Jaye; Murphy, Andrew J

    2017-10-01

    Monocyte levels predict cardiovascular outcomes and play a causal role in atherogenesis. Monocytes can be produced in the spleen and track to the atherosclerotic lesion in significant numbers. The cholinergic system has been shown to have anti-inflammatory actions in the spleen. We aimed to explore whether therapeutic stimulation of the nicotinic acetylcholine receptor alpha 7 (nAChRα7) can suppress atherogenesis. Apoe(-/-) mice were placed on a Western-type diet and treated with bi-daily injections of the nAChRα7 agonist GTS-21 or vehicle every 2-3 days for 8 weeks. GTS-21 caused a reduction in atherosclerosis in the aortic arch and proximal aorta. This also resulted in less plaque macrophages. Moreover, GTS-21 reduced the abundance of blood monocytes, which was caused by inhibition of inflammatory cytokines and extramedullary hematopoiesis in the spleen, along with splenic monocytes. Stimulation of nAChRα7 with GTS-21 reduced atherosclerosis, which was associated with dampened splenic myelopoiesis. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Levonorgestrel inhibits luteinizing hormone-stimulated progesterone production in rat luteal cells.

    PubMed

    Tellería, C M; Carrizo, D G; Deis, R P

    1994-08-01

    The effects of the synthetic progestin levonorgestrel (LNG) on basal and LH-stimulated progesterone production were studied in collagenase-dispersed luteal cells obtained from 9-day pregnant rats. Luteal cells responded to ovine LH (oLH) with an increase in progesterone output which was maximal at a dose of 100 ng/ml. No effect of LNG was observed at 0.1-10 microM, but at 100 microM, it inhibited basal progesterone production. On the other hand, a dose of 10 microM LNG suppressed the stimulation of progesterone secretion induced by oLH, dibutyryl-cAMP and pregnenolone. It is suggested that the possible mechanism of action of the progestin involves a post-cAMP site and, in some way, may lead to an interference with 3 beta-hydroxysteroid dehydrogenase activity, which catalyzes the formation of progesterone from pregnenolone, the last step of progesterone biosynthesis. This study provides a different point of view supporting an autocrine control mechanism by which progesterone, the principal steroidogenic product of luteal cells, may exert a negative ultra-short loop regulation of its own biosynthesis.

  9. Dietary fructo-oligosaccharides and lactulose inhibit intestinal colonisation but stimulate translocation of salmonella in rats

    PubMed Central

    Bovee-Oudenhoven, I M J; ten Bruggencate, S J M; Lettink-Wissink, M L G; van der Meer, R

    2003-01-01

    Background and aims: It is frequently assumed that dietary non-digestible carbohydrates improve host resistance to intestinal infections by stimulating the protective gut microflora. However, compelling scientific evidence from in vivo infection studies is lacking. Therefore, we studied the effect of several non-digestible carbohydrates on the resistance of rats to Salmonella enteritidis infection. Methods: Rats (n=8 per group) were fed “humanised” purified diets containing 4% lactulose, fructo-oligosaccharides (FOS), resistant starch, wheat fibre, or cellulose. After an adaptation period of 2 weeks the animals were orally infected with S enteritidis. Supplement induced changes in faecal biochemical and microbiological parameters were studied before infection. Colonisation of salmonella was determined by studying the faecal excretion of this pathogen and translocation by analysis of urinary nitric oxide metabolites over time and classical organ cultures. Intestinal mucosal myeloperoxidase activity was determined to quantify intestinal inflammation after infection. Results: Despite stimulation of intestinal lactobacilli and bifidobacteria and inhibition of salmonella colonisation, FOS and lactulose significantly enhanced translocation of this pathogen. These supplements also increased cytotoxicity of faecal water and faecal mucin excretion, which may reflect mucosal irritation. In addition, caecal and colonic, but not ileal, mucosal myeloperoxidase activity was increased in infected rats fed FOS and lactulose. In contrast, cellulose, wheat fibre, and resistant starch did not affect the resistance to salmonella. Conclusions: In contrast to most expectations, FOS and lactulose impair the resistance of rats to intestinal salmonella infection. Obviously, stimulation of the endogenous lactobacilli and bifidobacteria is no guarantee of improved host defence against intestinal infections. PMID:14570725

  10. Activation and inhibition of retinal ganglion cells in response to epiretinal electrical stimulation: a computational modelling study

    NASA Astrophysics Data System (ADS)

    Abramian, Miganoosh; Lovell, Nigel H.; Morley, John W.; Suaning, Gregg J.; Dokos, Socrates

    2015-02-01

    Objective. Retinal prosthetic devices aim to restore sight in visually impaired people by means of electrical stimulation of surviving retinal ganglion cells (RGCs). This modelling study aims to demonstrate that RGC inhibition caused by high-intensity cathodic pulses greatly influences their responses to epiretinal electrical stimulation and to investigate the impact of this inhibition on spatial activation profiles as well as their implications for retinal prosthetic device design. Another aim is to take advantage of this inhibition to reduce axonal activation in the nerve fibre layer. Approach. A three-dimensional finite-element model of epiretinal electrical stimulation was utilized to obtain RGC activation and inhibition threshold profiles for a range of parameters. Main results. RGC activation and inhibition thresholds were highly dependent on cell and stimulus parameters. Activation thresholds were 1.5, 3.4 and 11.3 μA for monopolar electrodes with 5, 20 and 50 μm radii, respectively. Inhibition to activation threshold ratios were mostly within the range 2-10. Inhibition significantly altered spatial patterns of RGC activation. With concentric electrodes and appropriately high levels of stimulus amplitudes, activation of passing axons was greatly reduced. Significance. RGC inhibition significantly impacts their spatial activation profiles, and therefore it most likely influences patterns of perceived phosphenes induced by retinal prosthetic devices. Thus this inhibition should be taken into account in future studies concerning retinal prosthesis development. It might be possible to utilize this inhibitory effect to bypass activation of passing axons and selectively stimulate RGCs near their somas and dendrites to achieve more localized phosphenes.

  11. Growth hormone induces hepatic production of fibroblast growth factor 21 through a mechanism dependent on lipolysis in adipocytes.

    PubMed

    Chen, Wei; Hoo, Ruby Lai-chong; Konishi, Morichika; Itoh, Nobuyuki; Lee, Pui-Chi; Ye, Hong-ying; Lam, Karen Siu-ling; Xu, Aimin

    2011-10-07

    Fibroblast growth factor (FGF) 21 and growth hormone (GH) are metabolic hormones that play important roles in regulating glucose and lipid metabolism. Both hormones are induced in response to fasting and exert their actions on adipocytes to regulate lipolysis. However, the molecular interaction between these two hormones remains unclear. Here we demonstrate the existence of a feedback loop between GH and FGF21 on the regulation of lipolysis in adipocytes. A single bolus injection of GH into C57 mice acutely increases both mRNA and protein expression of FGF21 in the liver, thereby leading to a marked elevation of serum FGF21 concentrations. Such a stimulatory effect of GH on hepatic FGF21 production is abrogated by pretreatment of mice with the lipolysis inhibitor niacin. Direct incubation of either liver explants or human HepG2 hepatocytes with GH has no effect on FGF21 expression. On the other hand, FGF21 production in HepG2 cells is significantly induced by incubation with the conditioned medium harvested from GH-treated adipose tissue explants, which contains high concentrations of free fatty acids (FFA). Further analysis shows that FFA released by GH-induced lipolysis stimulates hepatic FGF21 expression by activation of the transcription factor PPARα. In FGF21-null mice, both the magnitude and duration of GH-induced lipolysis are significantly higher than those in their wild type littermates. Taken together, these findings suggest that GH-induced hepatic FGF21 production is mediated by FFA released from adipose tissues, and elevated FGF21 in turn acts as a negative feedback signal to terminate GH-stimulated lipolysis in adipocytes.

  12. Low frequency mechanical stimulation inhibits adipogenic differentiation of C3H10T1/2 mesenchymal stem cells.

    PubMed

    Khayat, Ghazaleh; Rosenzweig, Derek H; Quinn, Thomas M

    2012-04-01

    Oscillatory mechanical stimulation at relatively high frequencies (0.1 Hz) has been shown to inhibit adipogenic and promote osteogenic differentiation of mesenchymal stem cells. However, for physiological interpretations and ease of implementation it is of interest to know whether different rates of mechanical stimulation can produce similar results. We hypothesized that relatively low frequency mechanical stimulation (0.01 Hz) can inhibit adipogenic differentiation of C3H10T1/2 mouse mesenchymal stem cells, even in a potent adipogenic differentiation medium. C3H10T1/2 cells were cultured in adipogenic medium under control (non-mechanically stimulated) conditions and under oscillatory surface stretch with 10% amplitude and 0.01 Hz frequency for 6h per day for up to 5 days. Cell population was assessed by counting and adipogenic differentiation was assessed by real-time quantitative PCR (qPCR) analysis of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid binding protein 4 (FABP4) after 3 and 5 days. Involvement of the ERK signaling pathway was assessed by Western blot. Low frequency mechanical stimulation significantly decreased expression of PPARγ after 3 days and FABP4 after 3 and 5 days versus non-stimulated culture. ERK signaling was decreased in mechanically-stimulated culture, indicating a role in the inhibition of adipogenic differentiation. Application of this study: Low frequency mechanical stimulation may provide a technically simple means for control of mesenchymal stem cell differentiation in cell-based therapies, particularly for inhibition of differentiation toward undesired adipogenic lineages. Copyright © 2012 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  13. Sex-specific inhibition and stimulation of worker-reproductive transition in a termite

    NASA Astrophysics Data System (ADS)

    Sun, Qian; Haynes, Kenneth F.; Hampton, Jordan D.; Zhou, Xuguo

    2017-10-01

    In social insects, the postembryonic development of individuals exhibits strong phenotypic plasticity in response to the environment, thus generating the caste system. Different from eusocial Hymenoptera, in which queens dominate reproduction and inhibit worker fertility, the primary reproductive caste in termites (kings and queens) can be replaced by neotenic reproductives derived from functionally sterile individuals. Feedback regulation of nestmate differentiation into reproductives has been suggested, but the sex specificity remains inconclusive. In the eastern subterranean termite, Reticulitermes flavipes, we tested the hypothesis that neotenic reproductives regulate worker-reproductive transition in a sex-specific manner. With this R. flavipes system, we demonstrate a sex-specific regulatory mechanism with both inhibitory and stimulatory functions. Neotenics inhibit workers of the same sex from differentiating into additional reproductives but stimulate workers of the opposite sex to undergo this transition. Furthermore, this process is not affected by the presence of soldiers. Our results highlight the reproductive plasticity of termites in response to social cues and provide insights into the regulation of reproductive division of labor in a hemimetabolous social insect.

  14. Tungstate stimulates insulin release and inhibits somatostatin output in the perfused rat pancreas.

    PubMed

    Silvestre, Ramona A; Egido, Eva M; Hernández, Raquel; Marco, José

    2005-09-05

    In the rat pancreas, infusion of sodium-tungstate stimulates basal insulin release in a dose-dependent manner. We have studied tungstate's effects on the insulin secretion elicited by various B-cell secretagogues. Somatostatin output was also measured. The study was performed in the perfused pancreas isolated from normal or somatostatin-depleted pancreases as induced by cysteamine pre-treatment. In control rats, tungstate co-infusion (5 mM) potentiated the insulin secretory responses to glucose (2.7-fold; P<0.01), arginine (2-fold; P<0.01), exendin-4 (3-fold; P<0.01), glucagon (4-fold; P<0.05), and tolbutamide (2-fold; P<0.01). It also inhibited the somatostatin secretory responses to glucose (90%; P<0.01), arginine (95%; P<0.01), glucagon (80%; P<0.025), exendin-4 (80%; P<0.05) and tolbutamide (85%; P<0.01). In somatostatin-depleted pancreases, the stimulatory effect of tungstate on basal insulin secretion and its potentiation of arginine-induced insulin output were comparable to those found in control rats. Our observations suggest an amplifying effect of tungstate on a common step in the insulin stimulus/secretion coupling process, and would rule out a paracrine effect mediated by the inhibition of somatostatin secretion induced by this compound.

  15. Mercury and protein thiols: Stimulation of mitochondrial F1FO-ATPase and inhibition of respiration.

    PubMed

    Nesci, Salvatore; Trombetti, Fabiana; Pirini, Maurizio; Ventrella, Vittoria; Pagliarani, Alessandra

    2016-12-25

    In spite of the known widespread toxicity of mercury, its impact on mitochondrial bioenergetics is a still poorly explored topic. Even if many studies have dealt with mercury poisoning of mitochondrial respiration, as far as we are aware Hg(2+) effects on individual complexes are not so clear. In the present study changes in swine heart mitochondrial respiration and F1FO-ATPase (F-ATPase) activity promoted by micromolar Hg(2+) concentrations were investigated. Hg(2+) was found to inhibit the respiration of NADH-energized mitochondria, whereas it was ineffective when the substrate was succinate. Interestingly, the same micromolar Hg(2+) doses which inhibited the NADH-O2 activity stimulated the F-ATPase, most likely by interacting with adjacent thiol residues. Accordingly, Hg(2+) dose-dependently decreased protein thiols and all the elicited effects on mitochondrial complexes were reversed by the thiol reducing agent DTE. These findings clearly indicate that Hg(2+) interacts with Cys residues of these complexes and differently modulate their functionality by modifying the redox state of thiol groups. The results, which cast light on some implications of metal-thiol interactions up to now not fully explored, may contribute to clarify the molecular mechanisms of mercury toxicity to mitochondria. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Facilitation and inhibition of jaw reflexes evoked by electrical stimulation of the cat's cerebral cortex.

    PubMed

    Olsson, K A; Landgren, S

    1980-01-01

    The effects of electrical stimulation of the cerebral cortex on the monosynaptic jaw closing and the disynaptic jaw opening reflexes were studied in cats anaesthetized with chloralose. The time course of the reflex effects was recorded. Similar rhythmic sequences of facilitation and inhibition were observed in both reflexes (Fig. 3). The sequence could start with facilitation or inhibition. The latency of the initial effects was short (2.5 ms) indicating a minimum of two synapses in the descending path. The period of the rhythmic sequence was approximately 10 ms. Optimal parameters for the conditioning cortisol stimuli were found to be: trains of 3-5 surface anodal pulses, 0.5 ms, 400 Hz. The threshold of the cortical effects on the reflexes was 0.3 mA. A single pulse evoked effects. The cortical origin of the effects was located and related to the somatosensory projections, and to the cytoarchitecture. The effects of largest amplitude and most complex time course were evoked from the oral and perioral projections to areas 3a and 3b. Effects evoked from areas 4 gamma, 5a, and 6a beta were less complex and of lower amplitude. It is suggested that a trigemino-cortico-trigeminal loop via 3a may function in reflex modulation of the jaw movements. In addition area 3a may contribute to cortico-cortical motor elaborations via U-fiber connections to area 4 gamma.

  17. Activation of AMPK Inhibits Cholera Toxin Stimulated Chloride Secretion in Human and Murine Intestine

    PubMed Central

    Hoekstra, Nadia; Collins, Danielle; Collaco, Anne; Baird, Alan W.; Winter, Desmond C.; Ameen, Nadia; Geibel, John P.; Kopic, Sascha

    2013-01-01

    Increased intestinal chloride secretion through chloride channels, such as the cystic fibrosis transmembrane conductance regulator (CFTR), is one of the major molecular mechanisms underlying enterotoxigenic diarrhea. It has been demonstrated in the past that the intracellular energy sensing kinase, the AMP-activated protein kinase (AMPK), can inhibit CFTR opening. We hypothesized that pharmacological activation of AMPK can abrogate the increased chloride flux through CFTR occurring during cholera toxin (CTX) mediated diarrhea. Chloride efflux was measured in isolated rat colonic crypts using real-time fluorescence imaging. AICAR and metformin were used to activate AMPK in the presence of the secretagogues CTX or forskolin (FSK). In order to substantiate our findings on the whole tissue level, short-circuit current (SCC) was monitored in human and murine colonic mucosa using Ussing chambers. Furthermore, fluid accumulation was measured in excised intestinal loops. CTX and forskolin (FSK) significantly increased chloride efflux in isolated colonic crypts. The increase in chloride efflux could be offset by using the AMPK activators AICAR and metformin. In human and mouse mucosal sheets, CTX and FSK increased SCC. AICAR and metformin inhibited the secretagogue induced rise in SCC, thereby confirming the findings made in isolated crypts. Moreover, AICAR decreased CTX stimulated fluid accumulation in excised intestinal segments. The present study suggests that pharmacological activation of AMPK effectively reduces CTX mediated increases in intestinal chloride secretion, which is a key factor for intestinal water accumulation. AMPK activators may therefore represent a supplemental treatment strategy for acute diarrheal illness. PMID:23935921

  18. Inhibition of nerve stimulation-induced vasodilatation in corpora cavernosa of the pithed rat by blockade of nitric oxide synthase.

    PubMed Central

    Finberg, J. P.; Levy, S.; Vardi, Y.

    1993-01-01

    1. The effect of inhibition of nitric oxide synthase by NG-nitro-L-arginine methyl ester (L-NAME) on nerve stimulation-induced vasodilation in corpora cavernosa was studied in the pithed rat. Corporal vasodilation was estimated by the increase in ratio (corpora cavernosal pressure/systemic blood pressure; CP/BP) following electrical stimulation of the sacral part of the spinal cord. 2. L-NAME (2, 5, 10 and 25 mg kg-1) caused an increase in BP and a dose-dependent inhibition of the rise in the CP/BP ratio following stimulation. 3. The inhibitory effect of L-NAME (25 mg kg-1) on the corporal response to spinal cord stimulation, as well as the pressor response, was partially prevented by prior administration of L- but not D-arginine (400 mg kg-1, i.v.). 4. L-NAME (20 mg kg-1, i.v.) did not inhibit the rise in corporal pressure resulting from direct intracavernosal administration of papaverine (400 micrograms over 2 min). However, this response was inhibited by 5-hydroxytryptamine (20 micrograms kg-1, i.v.). 5. The results are indicative of a role of nitric oxide (NO) in the corporal vasodilator response to erectile stimulation. PMID:7683562

  19. IL-21 Receptor Antagonist Inhibits Differentiation of B Cells toward Plasmablasts upon Alloantigen Stimulation

    PubMed Central

    de Leur, Kitty; Dor, Frank J. M. F.; Dieterich, Marjolein; van der Laan, Luc J. W.; Hendriks, Rudi W.; Baan, Carla C.

    2017-01-01

    Interaction between T follicular helper (Tfh) cells and B cells is complex and involves various pathways, including the production of IL-21 by the Tfh cells. Secretion of IL-21 results in B cell differentiation toward immunoglobulin-producing plasmablasts. In patients after kidney transplantation, the formation of alloantibodies produced by donor antigen-activated B cells are a major cause of organ failure. In this allogeneic response, the role of IL-21-producing Tfh cells that regulate B cell differentiation is unknown. Here, we tested, in an alloantigen-driven setting, whether Tfh cell help signals control B cell differentiation with its dependency on IL-21. Pre-transplantation patient PBMCs were sorted into pure CD4posCXCR5pos Tfh cells and CD19posCD27pos memory B cells and stimulated with donor antigen in the presence or absence of an IL-21 receptor (IL-21R) antagonist (αIL-21R). Donor antigen stimulation initiated expression of the activation markers inducible co-stimulator (ICOS) and programmed death 1 (PD-1) on Tfh cells and a shift toward a mixed Tfh2 and Tfh17 phenotype. The memory B cells underwent class switch recombination and differentiated toward IgM- and IgG-producing plasmablasts. In the presence of αIL-21R, a dose-dependent inhibition of STAT3 phosphorylation was measured in both T and B cells. Blockade of the IL-21R did not have an effect on PD-1 and ICOS expression on Tfh cells but significantly inhibited B cell differentiation. The proportion of plasmablasts decreased by 78% in the presence of αIL-21R. Moreover, secreted IgM and IgG2 levels were significantly lower in the presence of αIL-21R. In conclusion, our results demonstrate that IL-21 produced by alloantigen-activated Tfh cells controls B cell differentiation toward antibody producing plasmablasts. The IL-21R might, therefore, be a useful target in organ transplantation to prevent antigen-driven immune responses leading to graft failure. PMID:28373876

  20. Treatment of lipoma by injection lipolysis.

    PubMed

    Nanda, Soni

    2011-05-01

    Injection lipolysis or lipodissolve is the practice of injecting phosphatidyl choline/ sodium deoxycholate (PDC/DC) compounds in the subcutaneous fat. Though this practice is being used extensively for nonsurgical contouring of body and dissolving localized collections of excess fat, it's use as a treatment modality for lipomas needs further evaluation. We present a case where this technique was used for treating a lipoma, with no recurrence after 9 months of follow up. Injection lipolysis as a treatment modality for lipomas needs to be evaluated for safety and efficacy in trials on larger population. This could prove to be a very valuable adjunct to the current practice of excision, if done by a trained person in a properly selected patient. Also the side effects and the controversies regarding this procedure have been discussed in detail in the present paper.

  1. Inhibition of rab5 GTPase activity stimulates membrane fusion in endocytosis.

    PubMed Central

    Stenmark, H; Parton, R G; Steele-Mortimer, O; Lütcke, A; Gruenberg, J; Zerial, M

    1994-01-01

    Small GTPases of the rab family control distinct steps of intracellular transport. The function of their GTPase activity is not completely understood. To investigate the role of the nucleotide state of rab5 in the early endocytic pathway, the effects of two mutants with opposing biochemical properties were tested. The Q79L mutant of rab5, analogous with the activating Q61L mutant of p21-ras, was found to have a strongly decreased intrinsic GTPase activity and was, unlike wild-type rab5, found mainly in the GTP-bound form in vivo. Expression of this protein in BHK and HeLa cells led to a dramatic change in cell morphology, with the appearance of unusually large early endocytic structures, considerably larger than those formed upon overexpression of wild-type rab5. An increased rate of transferrin internalization was observed in these cells, whereas recycling was inhibited. Cytosol containing rab5 Q79L stimulated homotypic early endosome fusion in vitro, even though it contained only a small amount of the isoprenylated protein. A different mutant, rab5 S34N, was found, like the inhibitory p21-ras S17N mutant, to have a preferential affinity for GDP. Overexpression of rab5 S34N induced the accumulation of very small endocytic profile and inhibited transferrin endocytosis. This protein inhibited fusion between early endosomes in vitro. The opposite effects of the rab5 Q79L and S34N mutants suggest that rab5:GTP is required prior to membrane fusion, whereas GTP hydrolysis by rab5 occurs after membrane fusion and functions to inactivate the protein. Images PMID:8137813

  2. Plasticity of cortical inhibition in dystonia is impaired after motor learning and Paired-Associative Stimulation

    PubMed Central

    Meunier, Sabine; Russmann, Heike; Shamim, Ejaz; Lamy, Jean-Charles; Hallett, Mark

    2012-01-01

    Summary Artificial induction of plasticity by paired associative stimulation (PAS) in healthy subjects (HV) demonstrates Hebbian-like plasticity in selected inhibitory networks as well as excitatory ones. In a group of 17 patients with focal hand dystonia and a group of 19 HV, we evaluated how PAS and the learning of a simple motor task influence the circuits supporting long interval intracortical inhibition (LICI, reflecting activity of GABAB interneurons) and long latency afferent inhibition (LAI, reflecting activity of somatosensory inputs to the motor cortex). In HV, PAS and motor learning induced LTP-like plasticity of excitatory networks and a lasting decrease of LAI and LICI in the motor representation of the targeted or trained muscle. The better the motor performance, the larger was the decrease of LAI. Although motor performance in the patient group was similar to that of the control group, LAI did not decrease during the motor learning as it did in the control group. In contrast, LICI was normally modulated. In patients the results after PAS did not match those obtained after motor learning: LAI was paradoxically increased and LICI did not exhibit any change. In the normal situation, decreased excitability in inhibitory circuits after induction of LTP-like plasticity may help to shape the cortical maps according to the new sensorimotor task. In patients, the abnormal or absent modulation of afferent and intracortical long-interval inhibition might indicate maladaptive plasticity that possibly contributes to the difficulty that they have to learn a new sensorimotor task.“ PMID:22429246

  3. FAT SIGNALS - Lipases and Lipolysis in Lipid Metabolism and Signaling

    PubMed Central

    Zechner, Rudolf; Zimmermann, Robert; Eichmann, Thomas O.; Kohlwein, Sepp D.; Haemmerle, Guenter; Lass, Achim; Madeo, Frank

    2012-01-01

    Lipolysis is defined as the catabolism of triacylglycerols stored in cellular lipid droplets. Recent discoveries of essential lipolytic enzymes and characterization of numerous regulatory proteins and mechanisms have fundamentally changed our perception of lipolysis and its impact on cellular metabolism. New findings that lipolytic products and intermediates participate in cellular signaling processes and that “lipolytic signaling” is particularly important in many nonadipose tissues unveil a previously underappreciated aspect of lipolysis, which may be relevant for human disease. PMID:22405066

  4. Inhibition of atrial receptor-induced renal responses by stimulation of carotid baroreceptors in anaesthetized dogs.

    PubMed Central

    Karim, F; Majid, D S

    1991-01-01

    excitation of carotid baroreceptors can completely inhibit the reflex renal haemodynamic and functional responses to atrial receptor stimulation. PMID:1886066

  5. Anaesthetic agents inhibit gastrin-stimulated but not basal histamine release from rat stomach ECL cells.

    PubMed

    Norlén, P; Kitano, M; Lindström, E; Håkanson, R

    2000-06-01

    By mobilizing histamine in response to gastrin, the ECL cells in the oxyntic mucosa play a key role in the control of the parietal cells and hence of gastric acid secretion. General anaesthesia suppresses basal and gastrin- and histamine-stimulated acid secretion. The present study examines if the effect of anaesthesia on basal and gastrin-stimulated acid secretion is associated with suppressed ECL-cell histamine secretion. A microdialysis probe was implanted in the submucosa of the ventral aspect of the acid-producing part of the stomach (32 rats). Three days later, ECL-cell histamine mobilization was monitored 2 h before and 4 h after the start of intravenous infusion of gastrin (5 nmol kg(-1) h(-1)). The rats were either conscious or anaesthetized. Four commonly used anaesthetic agents were given 1 h before the start of the experiments by intraperitoneal injection: chloral hydrate (300 mg kg(-1)), pentobarbitone (40 mg kg(-1)), urethane (1.5 g kg(-1)) and a mixture of fluanisone/fentanyl/midazolam (15/0.5/7.5 mg kg(-1)). In a parallel series of experiments, basal- and gastrin-induced acid secretion was monitored in six conscious and 25 anaesthetized (see above) chronic gastric fistula rats. All anaesthetic agents lowered gastrin-stimulated acid secretion; also the basal acid output was reduced (fluanisone/fentanyl/midazolam was an exception). Anaesthesia reduced gastrin-stimulated but not basal histamine release by 55 - 80%. The reduction in gastrin-induced acid response (70 - 95%) was strongly correlated to the reduction in gastrin-induced histamine mobilization. The correlation is in line with the view that the reduced acid response to gastrin reflects impaired histamine mobilization. Rat stomach ECL cells were purified by counter-flow elutriation. Gastrin-evoked histamine mobilization from the isolated ECL cells was determined in the absence or presence of anaesthetic agents in the medium. With the exception of urethane, they inhibited gastrin

  6. AHNAK deficiency promotes browning and lipolysis in mice via increased responsiveness to β-adrenergic signalling.

    PubMed

    Shin, Jae Hoon; Lee, Seo Hyun; Kim, Yo Na; Kim, Il Yong; Kim, Youn Ju; Kyeong, Dong Soo; Lim, Hee Jung; Cho, Soo Young; Choi, Junhee; Wi, Young Jin; Choi, Jae-Hoon; Yoon, Yeo Sung; Bae, Yun Soo; Seong, Je Kyung

    2016-03-18

    In adipose tissue, agonists of the β3-adrenergic receptor (ADRB3) regulate lipolysis, lipid oxidation, and thermogenesis. The deficiency in the thermogenesis induced by neuroblast differentiation-associated protein AHNAK in white adipose tissue (WAT) of mice fed a high-fat diet suggests that AHNAK may stimulate energy expenditure via development of beige fat. Here, we report that AHNAK deficiency promoted browning and thermogenic gene expression in WAT but not in brown adipose tissue of mice stimulated with the ADRB3 agonist CL-316243. Consistent with the increased thermogenesis, Ahnak(-/-) mice exhibited an increase in energy expenditure, accompanied by elevated mitochondrial biogenesis in WAT depots in response to CL-316243. Additionally, AHNAK-deficient WAT contained more eosinophils and higher levels of type 2 cytokines (IL-4/IL-13) to promote browning of WAT in response to CL-316243. This was associated with enhanced sympathetic tone in the WAT via upregulation of adrb3 and tyrosine hydroxylase (TH) in response to β-adrenergic activation. CL-316243 activated PKA signalling and enhanced lipolysis, as evidenced by increased phosphorylation of hormone-sensitive lipase and release of free glycerol in Ahnak(-/-) mice compared to wild-type mice. Overall, these findings suggest an important role of AHNAK in the regulation of thermogenesis and lipolysis in WAT via β-adrenergic signalling.

  7. Beta cell compensation for insulin resistance in Zucker fatty rats: increased lipolysis and fatty acid signalling.

    PubMed

    Nolan, C J; Leahy, J L; Delghingaro-Augusto, V; Moibi, J; Soni, K; Peyot, M-L; Fortier, M; Guay, C; Lamontagne, J; Barbeau, A; Przybytkowski, E; Joly, E; Masiello, P; Wang, S; Mitchell, G A; Prentki, M

    2006-09-01

    The aim of this study was to determine the role of fatty acid signalling in islet beta cell compensation for insulin resistance in the Zucker fatty fa/fa (ZF) rat, a genetic model of severe obesity, hyperlipidaemia and insulin resistance that does not develop diabetes. NEFA augmentation of insulin secretion and fatty acid metabolism were studied in isolated islets from ZF and Zucker lean (ZL) control rats. Exogenous palmitate markedly potentiated glucose-stimulated insulin secretion (GSIS) in ZF islets, allowing robust secretion at physiological glucose levels (5-8 mmol/l). Exogenous palmitate also synergised with glucagon-like peptide-1 and the cyclic AMP-raising agent forskolin to enhance GSIS in ZF islets only. In assessing islet fatty acid metabolism, we found increased glucose-responsive palmitate esterification and lipolysis processes in ZF islets, suggestive of enhanced triglyceride-fatty acid cycling. Interruption of glucose-stimulated lipolysis by the lipase inhibitor Orlistat (tetrahydrolipstatin) blunted palmitate-augmented GSIS in ZF islets. Fatty acid oxidation was also higher at intermediate glucose levels in ZF islets and steatotic triglyceride accumulation was absent. The results highlight the potential importance of NEFA and glucoincretin enhancement of insulin secretion in beta cell compensation for insulin resistance. We propose that coordinated glucose-responsive fatty acid esterification and lipolysis processes, suggestive of triglyceride-fatty acid cycling, play a role in the coupling mechanisms of glucose-induced insulin secretion as well as in beta cell compensation and the hypersecretion of insulin in obesity.

  8. AHNAK deficiency promotes browning and lipolysis in mice via increased responsiveness to β-adrenergic signalling

    PubMed Central

    Shin, Jae Hoon; Lee, Seo Hyun; Kim, Yo Na; Kim, Il Yong; Kim, Youn Ju; Kyeong, Dong Soo; Lim, Hee Jung; Cho, Soo Young; Choi, Junhee; Wi, Young Jin; Choi, Jae-Hoon; Yoon, Yeo Sung; Bae, Yun Soo; Seong, Je Kyung

    2016-01-01

    In adipose tissue, agonists of the β3-adrenergic receptor (ADRB3) regulate lipolysis, lipid oxidation, and thermogenesis. The deficiency in the thermogenesis induced by neuroblast differentiation-associated protein AHNAK in white adipose tissue (WAT) of mice fed a high-fat diet suggests that AHNAK may stimulate energy expenditure via development of beige fat. Here, we report that AHNAK deficiency promoted browning and thermogenic gene expression in WAT but not in brown adipose tissue of mice stimulated with the ADRB3 agonist CL-316243. Consistent with the increased thermogenesis, Ahnak−/− mice exhibited an increase in energy expenditure, accompanied by elevated mitochondrial biogenesis in WAT depots in response to CL-316243. Additionally, AHNAK-deficient WAT contained more eosinophils and higher levels of type 2 cytokines (IL-4/IL-13) to promote browning of WAT in response to CL-316243. This was associated with enhanced sympathetic tone in the WAT via upregulation of adrb3 and tyrosine hydroxylase (TH) in response to β-adrenergic activation. CL-316243 activated PKA signalling and enhanced lipolysis, as evidenced by increased phosphorylation of hormone-sensitive lipase and release of free glycerol in Ahnak−/− mice compared to wild-type mice. Overall, these findings suggest an important role of AHNAK in the regulation of thermogenesis and lipolysis in WAT via β-adrenergic signalling. PMID:26987950

  9. Bulbospinal inhibition of PAD elicited by stimulation of afferent and motor axons in the isolated frog spinal cord and brainstem.

    PubMed

    González, H; Jiménez, I; Rudomin, P

    1992-01-01

    1. In the isolated spinal cord and brainstem of the frog, stimulation of the brainstem (BS) with trains of 3-4 pulses at 60-400 Hz produced dorsal root potentials (DRPs). The lowest threshold sites eliciting DRPs were located at the level of the obex up to about 2.5 mm rostrally, 0.5-1.2 mm laterally, between 0.5 and 1.6 mm depth. This region corresponds to the bulbar reticular formation (RF). 2. Stimulation of the RF with strengths below those required to produce DRPs, very effectively inhibited the DRPs produced by stimulation of a neighboring dorsal root (DR-DRPs) as well as the DRPs produced by antidromic stimulation of the central end of motor nerves (VR-DRPs). The inhibition was detectable 20 ms after the first pulse of the conditioning train, attained maximal values between 50 and 100 ms and lasted more than 250 ms. 3. Stimulation of the bulbar RF increased the negative response (N1 response) produced in the motor pool by antidromic activation of motoneurons. The time course of the facilitation of the N1 response resembled that of the reticularly-induced inhibition of the VR-DRPs and DR-DRPs. 4. The present series of observations supports the existence of reticulo-spinal pathways that are able to inhibit the depolarization elicited in afferent fibers by stimulation of other afferent fibers or by antidromic activation of motor axons. This inhibition appears to be exerted on the PAD mediating interneurons and is envisaged as playing an important role in motor control.

  10. Interleukin-1β inhibits insulin signaling and prevents insulin-stimulated system A amino acid transport in primary human trophoblasts.

    PubMed

    Aye, Irving L M H; Jansson, Thomas; Powell, Theresa L

    2013-12-05

    Interleukin-1β (IL-1β) promotes insulin resistance in tissues such as liver and skeletal muscle; however the influence of IL-1β on placental insulin signaling is unknown. We recently reported increased IL-1β protein expression in placentas of obese mothers, which could contribute to insulin resistance. In this study, we tested the hypothesis that IL-1β inhibits insulin signaling and prevents insulin-stimulated amino acid transport in cultured primary human trophoblast (PHT) cells. Cultured trophoblasts isolated from term placentas were treated with physiological concentrations of IL-1β (10pg/ml) for 24h. IL-1β increased the phosphorylation of insulin receptor substrate-1 (IRS-1) at Ser307 (inhibitory) and decreased total IRS-1 protein abundance but did not affect insulin receptor β expression. Furthermore, IL-1β inhibited insulin-stimulated phosphorylation of IRS-1 (Tyr612, activation site) and Akt (Thr308) and prevented insulin-stimulated increase in PI3K/p85 and Grb2 protein expression. IL-1β alone stimulated cRaf (Ser338), MEK (Ser221) and Erk1/2 (Thr202/Tyr204) phosphorylation. The inflammatory pathways nuclear factor kappa B and c-Jun N-terminal kinase, which are involved in insulin resistance, were also activated by IL-1β treatment. Moreover, IL-1β inhibited insulin-stimulated System A, but not System L amino acid uptake, indicating functional impairment of insulin signaling. In conclusion, IL-1β inhibited the insulin signaling pathway by inhibiting IRS-1 signaling and prevented insulin-stimulated System A transport, thereby promoting insulin resistance in cultured PHT cells. These findings indicate that conditions which lead to increased systemic maternal or placental IL-1β levels may attenuate the effects of maternal insulin on placental function and consequently fetal growth.

  11. Serum Amyloid A3 Secreted by Preosteoclasts Inhibits Parathyroid Hormone-stimulated cAMP Signaling in Murine Osteoblasts*

    PubMed Central

    Choudhary, Shilpa; Goetjen, Alexandra; Estus, Thomas; Jacome-Galarza, Christian E.; Aguila, Hector L.; Lorenzo, Joseph; Pilbeam, Carol

    2016-01-01

    Continuous parathyroid hormone (PTH) blocks its own osteogenic actions in marrow stromal cell cultures by inducing Cox2 and receptor activator of nuclear factor κB ligand (RANKL) in the osteoblastic lineage cells, which then cause the hematopoietic lineage cells to secrete an inhibitor of PTH-stimulated osteoblast differentiation. To identify this inhibitor, we used bone marrow macrophages (BMMs) and primary osteoblasts (POBs) from WT and Cox2 knock-out (KO) mice. Conditioned medium (CM) from RANKL-treated WT, but not KO, BMMs blocked PTH-stimulated cAMP production in POBs. Inhibition was reversed by pertussis toxin (PTX), which blocks Gαi/o activation. Saa3 was the most highly differentially expressed gene in a microarray comparison of RANKL-treated WT versus Cox2 KO BMMs, and RANKL induced Saa3 protein secretion only from WT BMMs. CM from RANKL-stimulated BMMs with Saa3 knockdown did not inhibit PTH-stimulated responses in POBs. SAA added to POBs inhibited PTH-stimulated cAMP responses, which was reversed by PTX. Selective agonists and antagonists of formyl peptide receptor 2 (Fpr2) suggested that Fpr2 mediated the inhibitory actions of Saa3 on osteoblasts. In BMMs committed to become osteoclasts by RANKL treatment, Saa3 expression peaked prior to appearance of multinucleated cells. Flow sorting of WT marrow revealed that Saa3 was secreted only from the RANKL-stimulated B220− CD3−CD11b−/low CD115+ preosteoclast population. We conclude that Saa3 secretion from preosteoclasts, induced by RANKL in a Cox2-dependent manner, inhibits PTH-stimulated cAMP signaling and osteoblast differentiation via Gαi/o signaling. The induction of Saa3 by PTH may explain the suppression of bone formation when PTH is applied continuously and may be a new therapeutic target for osteoporosis. PMID:26703472

  12. Slowing down fat digestion and absorption by an oxadiazolone inhibitor targeting selectively gastric lipolysis.

    PubMed

    Point, Vanessa; Bénarouche, Anais; Zarrillo, Julie; Guy, Alexandre; Magnez, Romain; Fonseca, Laurence; Raux, Brigitt; Leclaire, Julien; Buono, Gérard; Fotiadu, Frédéric; Durand, Thierry; Carrière, Frédéric; Vaysse, Carole; Couëdelo, Leslie; Cavalier, Jean-François

    2016-11-10

    Based on a previous study and in silico molecular docking experiments, we have designed and synthesized a new series of ten 5-Alkoxy-N-3-(3-PhenoxyPhenyl)-1,3,4-Oxadiazol-2(3H)-one derivatives (RmPPOX). These molecules were further evaluated as selective and potent inhibitors of mammalian digestive lipases: purified dog gastric lipase (DGL) and guinea pig pancreatic lipase related protein 2 (GPLRP2), as well as porcine (PPL) and human (HPL) pancreatic lipases contained in porcine pancreatic extracts (PPE) and human pancreatic juices (HPJ), respectively. These compounds were found to strongly discriminate classical pancreatic lipases (poorly inhibited) from gastric lipase (fully inhibited). Among them, the 5-(2-(Benzyloxy)ethoxy)-3-(3-PhenoxyPhenyl)-1,3,4-Oxadiazol-2(3H)-one (BemPPOX) was identified as the most potent inhibitor of DGL, even more active than the FDA-approved drug Orlistat. BemPPOX and Orlistat were further compared in vitro in the course of test meal digestion, and in vivo with a mesenteric lymph duct cannulated rat model to evaluate their respective impacts on fat absorption. While Orlistat inhibited both gastric and duodenal lipolysis and drastically reduced fat absorption in rats, BemPPOX showed a specific action on gastric lipolysis that slowed down the overall lipolysis process and led to a subsequent reduction of around 55% of the intestinal absorption of fatty acids compared to controls. All these data promote BemPPOX as a potent candidate to efficiently regulate the gastrointestinal lipolysis, and to investigate its link with satiety mechanisms and therefore develop new strategies to "fight against obesity".

  13. Progesterone-induced down-regulation of hormone sensitive lipase (Lipe) and up-regulation of G0/G1 switch 2 (G0s2) genes expression in inguinal adipose tissue of female rats is reflected by diminished rate of lipolysis.

    PubMed

    Stelmanska, Ewa; Szrok, Sylwia; Swierczynski, Julian

    2015-03-01

    Decreased lipolytic activity in adipose tissue may be one of the reasons behind excess accumulation of body fat during pregnancy. The aim of this study was to analyze the effect of progesterone on the expression of: (a) Lipe (encoding hormone-sensitive lipase, HSL), (b) Pnpla2 (encoding adipose triglyceride lipase, ATGL), (c) abhydrolase domain containing 5 (Abhd5), and (d) G0/G1 switch 2 (G0s2) genes in white adipose tissue (WAT), as potential targets for progesterone action during the course of pregnancy. Administration of progesterone to female rats, which was reflected by approximately 2.5-fold increase in circulating progesterone concentration, is associated with a decrease in Lipe gene expression in the inguinal WAT. The expression of Pnpla2 gene in all main fat depots of females and males remained unchanged after progesterone administration. Administration of progesterone resulted in an increase in the expression of Abhd5 gene (whose product increases ATGL activity) and G0s2 gene (whose product decreases ATGL activity) in the inguinal WAT of female rats. Mifepristone, a selective antagonist of progesterone receptor, abolished the effect of progesterone on Lipe, Abhd5 and G0s2 genes expression in the inguinal WAT. The decrease in Lipe and the increase in Abhd5 and G0s2 genes expression was associated with lower rate of stimulated lipolysis. Administration of progesterone exerted no effect on Lipe, Abhd5 and G0s2 genes expression and stimulated lipolysis in the retroperitoneal WAT of females, as well as in the inguinal, epididymal and retroperitoneal WAT of males. In conclusion, our findings suggest that progesterone decreases the rate of lipolysis in the inguinal WAT of female rats, inhibiting the activity of both ATGL (by stimulating synthesis of G0S2 - specific inhibitor of the enzyme) and HSL (due to inhibition of Lipe gene expression). Copyright © 2014. Published by Elsevier Ltd.

  14. NH4+-stimulated and -inhibited components of K+ transport in rice (Oryza sativa L.)

    PubMed Central

    Szczerba, Mark W.; Britto, Dev T.; Ali, Shabana A.; Balkos, Konstantine D.; Kronzucker, Herbert J.

    2008-01-01

    The disruption of K+ transport and accumulation is symptomatic of NH4+ toxicity in plants. In this study, the influence of K+ supply (0.02–40 mM) and nitrogen source (10 mM NH4+ or NO3–) on root plasma membrane K+ fluxes and cytosolic K+ pools, plant growth, and whole-plant K+ distribution in the NH4+-tolerant plant species rice (Oryza sativa L.) was examined. Using the radiotracer 42K+, tissue mineral analysis, and growth data, it is shown that rice is affected by NH4+ toxicity under high-affinity K+ transport conditions. Substantial recovery of growth was seen as [K+]ext was increased from 0.02 mM to 0.1 mM, and, at 1.5 mM, growth was superior on NH4+. Growth recovery at these concentrations was accompanied by greater influx of K+ into root cells, translocation of K+ to the shoot, and tissue K+. Elevating the K+ supply also resulted in a significant reduction of NH4+ influx, as measured by 13N radiotracing. In the low-affinity K+ transport range, NH4+ stimulated K+ influx relative to NO3– controls. It is concluded that rice, despite its well-known tolerance to NH4+, nevertheless displays considerable growth suppression and disruption of K+ homeostasis under this N regime at low [K+]ext, but displays efficient recovery from NH4+ inhibition, and indeed a stimulation of K+ acquisition, when [K+]ext is increased in the presence of NH4+. PMID:18653690

  15. AR-12 Inhibits Multiple Chaperones Concomitant With Stimulating Autophagosome Formation Collectively Preventing Virus Replication.

    PubMed

    Booth, Laurence; Roberts, Jane L; Ecroyd, Heath; Tritsch, Sarah R; Bavari, Sina; Reid, St Patrick; Proniuk, Stefan; Zukiwski, Alexander; Jacob, Abraham; Sepúlveda, Claudia S; Giovannoni, Federico; García, Cybele C; Damonte, Elsa; González-Gallego, Javier; Tuñón, María J; Dent, Paul

    2016-10-01

    We have recently demonstrated that AR-12 (OSU-03012) reduces the function and ATPase activities of multiple HSP90 and HSP70 family chaperones. Combined knock down of chaperones or AR-12 treatment acted to reduce the expression of virus receptors and essential glucosidase proteins. Combined knock down of chaperones or AR-12 treatment inactivated mTOR and elevated ATG13 S318 phosphorylation concomitant with inducing an endoplasmic reticulum stress response that in an eIF2α-dependent fashion increased Beclin1 and LC3 expression and autophagosome formation. Over-expression of chaperones prevented the reduction in receptor/glucosidase expression, mTOR inactivation, the ER stress response, and autophagosome formation. AR-12 reduced the reproduction of viruses including Mumps, Influenza, Measles, Junín, Rubella, HIV (wild type and protease resistant), and Ebola, an effect replicated by knock down of multiple chaperone proteins. AR-12-stimulated the co-localization of Influenza, EBV and HIV virus proteins with LC3 in autophagosomes and reduced viral protein association with the chaperones HSP90, HSP70, and GRP78. Knock down of Beclin1 suppressed drug-induced autophagosome formation and reduced the anti-viral protection afforded by AR-12. In an animal model of hemorrhagic fever virus, a transient exposure of animals to low doses of AR-12 doubled animal survival from ∼30% to ∼60% and suppressed liver damage as measured by ATL, GGT and LDH release. Thus through inhibition of chaperone protein functions; reducing the production, stability and processing of viral proteins; and stimulating autophagosome formation/viral protein degradation, AR-12 acts as a broad-specificity anti-viral drug in vitro and in vivo. We argue future patient studies with AR-12 are warranted. J. Cell. Physiol. 231: 2286-2302, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  16. Cortical Inhibition in Attention Deficit Hyperactivity Disorder: New Insights from the Electroencephalographic Response to Transcranial Magnetic Stimulation

    ERIC Educational Resources Information Center

    Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M.; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

    2012-01-01

    Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the…

  17. A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder

    ERIC Educational Resources Information Center

    Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

    2010-01-01

    Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS). Method: Participants were diagnosed by…

  18. Cortical Inhibition in Attention Deficit Hyperactivity Disorder: New Insights from the Electroencephalographic Response to Transcranial Magnetic Stimulation

    ERIC Educational Resources Information Center

    Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M.; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

    2012-01-01

    Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the…

  19. A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder

    ERIC Educational Resources Information Center

    Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

    2010-01-01

    Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS). Method: Participants were diagnosed by…

  20. Both inflammatory and classical lipolytic pathways are involved in lipopolysaccharide-induced lipolysis in human adipocytes.

    PubMed

    Grisouard, Jean; Bouillet, Elisa; Timper, Katharina; Radimerski, Tanja; Dembinski, Kaethi; Frey, Daniel M; Peterli, Ralph; Zulewski, Henryk; Keller, Ulrich; Müller, Beat; Christ-Crain, Mirjam

    2012-02-01

    High fat diet-induced endotoxaemia triggers low-grade inflammation and lipid release from adipose tissue. This study aims to unravel the cellular mechanisms leading to the lipopolysaccharide (LPS) effects in human adipocytes. Subcutaneous pre-adipocytes surgically isolated from patients were differentiated into mature adipocytes in vitro. Lipolysis was assessed by measurement of glycerol release and mRNA expression of pro-inflammatory cytokines were evaluated by real-time PCR. Treatment with LPS for 24 h induced a dose-dependent increase in interleukin (IL)-6 and IL-8 mRNA expression. At 1 µg/ml LPS, IL-6 and IL-8 were induced to 19.5 ± 1.8-fold and 662.7 ± 91.5-fold (P < 0.01 vs basal), respectively. From 100 ng/ml to 1 µg/ml, LPS-induced lipolysis increased to a plateau of 3.1-fold above basal level (P < 0.001 vs basal). Co-treatment with inhibitors of inhibitory kappa B kinase kinase beta (IKKβ) or NF-κB inhibited LPS-induced glycerol release. Co-treatment with the protein kinase A (PKA) inhibitor H-89, the lipase inhibitor orlistat or the hormone-sensitive lipase (HSL) inhibitor CAY10499 abolished the lipolytic effects of LPS. Co-treatment with the MAPK inhibitor, U0126 also reduced LPS-induced glycerol release. Inhibition of lipolysis by orlistat or CAY10499 reduced LPS-induced IL-6 and IL-8 mRNA expression. Induction of lipolysis by the synthetic catecholamine isoproterenol or the phosphodiesterase type III inhibitor milrinone did not alter basal IL-6 and IL-8 mRNA expression after 24 treatments whereas these compounds enhanced LPS-induced IL-6 and IL-8 mRNA expression. Both the inflammatory IKKβ/NF-κB pathway and the lipolytic PKA/HSL pathways mediate LPS-induced lipolysis. In turn, LPS-induced lipolysis reinforces the expression of pro-inflammatory cytokines and, thereby, triggers its own lipolytic activity.

  1. Immobilized alpha-melanocyte stimulating hormone 10-13 (GKPV) inhibits tumor necrosis factor-alpha stimulated NF-kappaB activity.

    PubMed

    Kelly, J M; Moir, A J G; Carlson, K; Yang, Y; MacNeil, S; Haycock, J W

    2006-02-01

    alpha-MSH is an anti-inflammatory peptide which signals by binding to the melanocortin-1 receptor (MC1R) and elevating cyclic AMP in several different cells and tissues. The carboxyl terminal peptides of alpha-MSH (KPV/GKPV) are the smallest minimal sequences that prevent inflammation, but it is not known if they operate via MC1R or cyclic AMP. The aim of this study was to examine the intracellular signaling potential of the GKPV peptide sequence when immobilized to polystyrene beads via a polyethylene glycol moiety. Beads containing an immobilized GKPV peptide were investigated for their ability to inhibit proinflammatory tumor necrosis factor-alpha (TNF-alpha) stimulated activation of NF-kappaB in HBL cells stably transfected with an NF-kappaB-luciferase reporter construct. Peptide functionalized beads were compared with the ability of soluble peptide alone (alpha-MSH or GKPV) or non-functionalized beads to inhibit TNF-alpha stimulated activation of NF-kappaB. GKPV peptide functionalized beads significantly inhibited NF-kappaB-luciferase activity in comparison to beads containing no peptide moiety in one of two growths conditions investigated. Soluble alpha-MSH and GKPV peptides were also confirmed to inhibit NF-kappaB-luciferase. The present study suggests that the carboxyl terminal MSH peptide acts via a cell receptor-based mechanism and furthermore may support the potential use of such immobilized ligands for anti-inflammatory therapeutic use.

  2. Endothelin-1 inhibits pre-stimulated tracheal submucosal gland secretion and epithelial albumin transport.

    PubMed Central

    Yurdakos, E.; Webber, S. E.

    1991-01-01

    1. Endothelin-1 potently contracts smooth muscle, including that in the airways. However, its effect on airway mucosal function has not so far been studied. 2. We have used the ferret whole trachea in vitro to examine the effect of endothelin-1 on tracheal smooth muscle tone, transepithelial potential difference (p.d.), submucosal gland secretion (including lysozyme secretion from serous cells) and active epithelial albumin transport. In addition we have examined the effects of endothelin on submucosal gland secretion and albumin transport pre-stimulated with the muscarinic agonist methacholine and the alpha-adrenoceptor agonist phenylephrine. The effects of the Ca2+ channel blocker nifedipine on the responses to endothelin have also been assessed. 3. Endothelin (0.1-100 nM) produced concentration-dependent increases in intraluminal tracheal pressure indicating smooth muscle contraction, and in the negativity of the transepithelial p.d. These effects were partially inhibited by nifedipine (10 microM). 4. Endothelin (0.01-100 nM) had no significant effect on baseline rates of mucus, lysozyme or albumin outputs, but produced concentration-dependent reductions in maintained methacholine- and phenylephrine-induced mucus, lysozyme and albumin outputs. In general endothelin was more potent against methacholine-induced effects. All of the concentration-response curves for endothelin were shallow and some appeared to be biphasic, suggesting the possibility of more than one mechanism of action of endothelin. 5. The effects of endothelin (at concentrations greater than 1 nM) on phenylephrine-induced mucus volume, lysozyme and albumin outputs were significantly inhibited by nifedipine. Similarly the effect of endothelin (greater than 1 nM) on methacholine-induced mucus volume and albumin outputs (but not lysozyme output) was attenuated by nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1810592

  3. Forskolin inhibits the Gs-stimulated adenylate cyclase in rat ascites hepatoma AH66F cells.

    PubMed

    Miyamoto, K; Sanae, F; Koshiura, R; Matsunaga, T; Hasegawa, T; Takagi, K; Satake, T

    1989-09-01

    Forskolin increased intracellular cyclic AMP and augmented cyclic AMP formation by prostaglandin E1 (PGE1) in normal rat hepatocytes and ascites hepatoma AH66 cells. However, in AH66F cells which were derived from the AH66 cell line, the diterpene only slightly increased the cyclic AMP level, and dose-dependently inhibited the accumulation caused by PGE1. Forskolin dose-dependently activated adenylate cyclase in these membranes, and the magnitude of activation by forskolin was largest in the following order: hepatocytes, AH66 cells, and AH66F cells. This difference may be based on the number of forskolin-binding sites. The binding affinity of forskolin for each cell membrane was similar. The number and affinity of forskolin-binding sites in these cells were not influenced by 5'-guanylylimidodiphosphate [Gpp(NH)p]. In hepatocytes and AH66 cells, forskolin and other adenylate cyclase activators such as PGE1, GTP, Gpp(NH)p, F-, and Mn2+ synergistically increased the enzyme activity. In AH66F cells, the forskolin-stimulated activity was hardly influenced by the GTP analog, and forskolin diminished the activities induced by the GTP analog in a manner similar to that of diterpene alone. Forskolin (10 microM) also significantly inhibited the activities induced by PGE1, GTP, and F-. The effect of forskolin with Mn2+ was additive in AH66F cells. The data suggest that forskolin promotes the interaction between the stimulatory guanine nucleotide-binding protein and the catalytic unit in the membrane of normal hepatocytes and AH66 cells, but it interferes with the coupling in AH66F cells.

  4. Effect of di(2-ethylhexyl) phthalate (DEHP) on lipolysis and lipoprotein lipase activities in adipose tissue of rats.

    PubMed

    Martinelli, Marcela I; Mocchiutti, Norberto O; Bernal, Claudio A

    2010-09-01

    The di(2-ethylhexyl) phthalate (DEHP) is an ubiquitous environmental chemical with detrimental health effects. The present work was designed to asses some potential mechanisms by which DEHP causes, among others, a reduced body fat retention. Since this effect could be related to an alteration of adipocyte triacylglycerol (TG) metabolism, we evaluated the effects of dietary DEHP in adipose tissues upon (1) the number and size of fat cells; (2) the basal and stimulated lipolysis and (3) the lipoprotein lipase (LPL) activity. Groups of male Wistar rats were fed for 21 days a control diet alone (control group) or the same control diet supplemented with 2% (w/w) of DEHP (DEHP group). The LPL activity of DEHP-fed rats was increased in lumbar and epididymal adipose tissues. These rats had significantly reduced weight in epididymal and lumbar tissues, together with reduced size of epididymal adipocytes. These alterations do not seem to be associated with higher lipid mobility because neither basal lipolysis nor 'in vitro' stimulated lipolysis by noradrenaline (NA) showed to be modified by DEHP. Based on these results, we concluded that the adipose tissue size reduction induced by DEHP intake is not due to changes in lipolysis nor to a decreased LPL activity. More research is needed to achieve a comprehensive understanding of the potential mechanisms by which DEHP causes, among others, a reduced body fat retention.

  5. Insulin and Metabolic Stress Stimulate Multisite Serine/Threonine Phosphorylation of Insulin Receptor Substrate 1 and Inhibit Tyrosine Phosphorylation*

    PubMed Central

    Hançer, Nancy J.; Qiu, Wei; Cherella, Christine; Li, Yedan; Copps, Kyle D.; White, Morris F.

    2014-01-01

    IRS1 and IRS2 are key substrates of the insulin receptor tyrosine kinase. Mass spectrometry reveals more than 50 phosphorylated IRS1 serine and threonine residues (Ser(P)/Thr(P) residues) in IRS1 from insulin-stimulated cells or human tissues. We investigated a subset of IRS1 Ser(P)/Thr(P) residues using a newly developed panel of 25 phospho-specific monoclonal antibodies (αpS/TmAbIrs1). CHO cells overexpressing the human insulin receptor and rat IRS1 were stimulated with insulin in the absence or presence of inhibitors of the PI3K → Akt → mechanistic target of rapamycin (mTOR) → S6 kinase or MEK pathways. Nearly all IRS1 Ser(P)/Thr(P) residues were stimulated by insulin and significantly suppressed by PI3K inhibition; fewer were suppressed by Akt or mTOR inhibition, and none were suppressed by MEK inhibition. Insulin-stimulated Irs1 tyrosine phosphorylation (Tyr(P)Irs1) was enhanced by inhibition of the PI3K → Akt → mTOR pathway and correlated with decreased Ser(P)-302Irs1, Ser(P)-307Irs1, Ser(P)-318Irs1, Ser(P)-325Irs1, and Ser(P)-346Irs1. Metabolic stress modeled by anisomycin, thapsigargin, or tunicamycin increased many of the same Ser(P)/Thr(P) residues as insulin, some of which (Ser(P)-302Irs1, Ser(P)-307Irs1, and four others) correlated significantly with impaired insulin-stimulated Tyr(P)Irs1. Thus, IRS1 Ser(P)/Thr(P) is an integrated response to insulin stimulation and metabolic stress, which associates with reduced Tyr(P)Irs1 in CHOIR/IRS1 cells. PMID:24652289

  6. Insulin and metabolic stress stimulate multisite serine/threonine phosphorylation of insulin receptor substrate 1 and inhibit tyrosine phosphorylation.

    PubMed

    Hançer, Nancy J; Qiu, Wei; Cherella, Christine; Li, Yedan; Copps, Kyle D; White, Morris F

    2014-05-02

    IRS1 and IRS2 are key substrates of the insulin receptor tyrosine kinase. Mass spectrometry reveals more than 50 phosphorylated IRS1 serine and threonine residues (Ser(P)/Thr(P) residues) in IRS1 from insulin-stimulated cells or human tissues. We investigated a subset of IRS1 Ser(P)/Thr(P) residues using a newly developed panel of 25 phospho-specific monoclonal antibodies (αpS/TmAb(Irs1)). CHO cells overexpressing the human insulin receptor and rat IRS1 were stimulated with insulin in the absence or presence of inhibitors of the PI3K → Akt → mechanistic target of rapamycin (mTOR) → S6 kinase or MEK pathways. Nearly all IRS1 Ser(P)/Thr(P) residues were stimulated by insulin and significantly suppressed by PI3K inhibition; fewer were suppressed by Akt or mTOR inhibition, and none were suppressed by MEK inhibition. Insulin-stimulated Irs1 tyrosine phosphorylation (Tyr(P)(Irs1)) was enhanced by inhibition of the PI3K → Akt → mTOR pathway and correlated with decreased Ser(P)-302(Irs1), Ser(P)-307(Irs1), Ser(P)-318(Irs1), Ser(P)-325(Irs1), and Ser(P)-346(Irs1). Metabolic stress modeled by anisomycin, thapsigargin, or tunicamycin increased many of the same Ser(P)/Thr(P) residues as insulin, some of which (Ser(P)-302(Irs1), Ser(P)-307(Irs1), and four others) correlated significantly with impaired insulin-stimulated Tyr(P)(Irs1). Thus, IRS1 Ser(P)/Thr(P) is an integrated response to insulin stimulation and metabolic stress, which associates with reduced Tyr(P)(Irs1) in CHO(IR)/IRS1 cells.

  7. Activation of the lipid droplet controls the rate of lipolysis of triglycerides in the insect fat body.

    PubMed

    Patel, Rajesh T; Soulages, Jose L; Hariharasundaram, Balaji; Arrese, Estela L

    2005-06-17

    The hydrolysis of triglyceride (TG) stored in the lipid droplets of the insect fat body is under hormonal regulation by the adipokinetic hormone (AKH), which triggers a rapid activation cAMP-dependent kinase cascade (protein kinase A (PKA)). The role of phosphorylation on two components of the lipolytic process, the TG-lipase and the lipid droplet, was investigated in fat body adipocytes. The activity of purified TG-lipase determined using in vivo TG-radiolabeled lipid droplets was unaffected by the phosphorylation of the lipase. However, the activity of purified lipase was 2.4-fold higher against lipid droplets isolated from hormone-stimulated fat bodies than against lipid droplets isolated from unstimulated tissue. In vivo stimulation of lipolysis promotes a rapid phosphorylation of a lipid droplet protein with an apparent mass of 42-44 kDa. This protein was identified as "Lipid Storage Droplet Protein 1" (Lsdp1). In vivo phosphorylation of this protein reached a peak approximately 10 min after the injection of AKH. Supporting a role of Lsdp1 in lipolysis, maximum TG-lipase activity was also observed with lipid droplets isolated 10 min after hormonal stimulation. The activation of lipolysis was reconstituted in vitro using purified insect PKA and TG-lipase and lipid droplets. In vitro phosphorylation of lipid droplets catalyzed by PKA enhanced the phosphorylation of Lsdp1 and the lipolytic rate of the lipase, demonstrating a prominent role PKA and protein phosphorylation on the activation of the lipid droplets. AKH-induced changes in the properties of the substrate do not promote a tight association of the lipase with the lipid droplets. It is concluded that the lipolysis in fat body adipocytes is controlled by the activation of the lipid droplet. This activation is achieved by PKA-mediated phosphorylation of the lipid droplet. Lsdp1 is the main target of PKA, suggesting that this protein is a major player in the activation of lipolysis in insects.

  8. Stimulation and inhibition of enzymatic hydrolysis by organosolv lignins as determined by zeta potential and hydrophobicity.

    PubMed

    Huang, Yang; Sun, Shaolong; Huang, Chen; Yong, Qiang; Elder, Thomas; Tu, Maobing

    2017-01-01

    Lignin typically inhibits enzymatic hydrolysis of cellulosic biomass, but certain organosolv lignins or lignosulfonates enhance enzymatic hydrolysis. The hydrophobic and electrostatic interactions between lignin and cellulases play critical roles in the enzymatic hydrolysis process. However, how to incorporate these two interactions into the consideration of lignin effects has not been investigated. We examined the physicochemical properties and the structures of ethanol organosolv lignins (EOL) from hardwood and softwood and ascertained the association between lignin properties and their inhibitory and stimulatory effects on enzymatic hydrolysis. The zeta potential and hydrophobicity of EOL lignin samples, isolated from organosolv pretreatment of cottonwood (CW), black willow (BW), aspen (AS), eucalyptus (EH), and loblolly pine (LP), were determined and correlated with their effects on enzymatic hydrolysis of Avicel. EOLs from CW, BW, and AS improved the 72 h hydrolysis yield by 8-12%, while EOLs from EH and LP decreased the 72 h hydrolysis yield by 6 and 16%, respectively. The results showed a strong correlation between the 72 h hydrolysis yield with hydrophobicity and zeta potential. The correlation indicated that the hydrophobicity of EOL had a negative effect and the negative zeta potential of EOL had a positive effect. HSQC NMR spectra showed that β-O-4 linkages in lignin react with ethanol to form an α-ethoxylated β-O-4' substructure (A') during organosolv pretreatment. Considerable amounts of C2,6-H2,6 correlation in p-hydroxybenzoate (PB) units were observed for EOL-CW, EOL-BW, and EOL-AS, but not for EOL-EH and EOL-LP. This study revealed that the effect of lignin on enzymatic hydrolysis is a function of both hydrophobic interactions and electrostatic repulsions. The lignin inhibition is controlled by lignin hydrophobicity and the lignin stimulation is governed by the negative zeta potential. The net effect of lignin depends on the combined

  9. PhCESA3 silencing inhibits elongation and stimulates radial expansion in petunia

    PubMed Central

    Yang, Weiyuan; Cai, Yuanping; Hu, Li; Wei, Qian; Chen, Guoju; Bai, Mei; Wu, Hong; Liu, Juanxu; Yu, Yixun

    2017-01-01

    Cellulose synthase catalytic subunits (CESAs) play important roles in plant growth, development and disease resistance. Previous studies have shown an essential role of Arabidopsis thaliana CESA3 in plant growth. However, little is known about the role of CESA3 in species other than A. thaliana. To gain a better understanding of CESA3, the petunia (Petunia hybrida) PhCESA3 gene was isolated, and the role of PhCESA3 in plant growth was analyzed in a wide range of plants. PhCESA3 mRNA was present at varying levels in tissues examined. VIGS-mediated PhCESA3 silencing resulted in dwarfing of plant height, which was consistent with the phenotype of the A. thaliana rsw1 mutant (a temperature-sensitive allele of AtCESA1), the A. thaliana cev1 mutant (the AtCESA3 mild mutant), and the antisense AtCESA3 line. However, PhCESA3 silencing led to swollen stems, pedicels, filaments, styles and epidermal hairs as well as thickened leaves and corollas, which were not observed in the A. thaliana cev1 mutant, the rsw1 mutant and the antisense AtCESA3 line. Further micrographs showed that PhCESA3 silencing reduced the length and increased the width of cells, suggesting that PhCESA3 silencing inhibits elongation and stimulates radial expansion in petunia. PMID:28150693

  10. Continuous theta-burst stimulation over primary somatosensory cortex modulates short-latency afferent inhibition.

    PubMed

    Tsang, Philemon; Jacobs, Mark F; Lee, Kevin G H; Asmussen, Michael J; Zapallow, Christopher M; Nelson, Aimee J

    2014-11-01

    The present study investigated the effects of continuous theta-burst stimulation (cTBS) over primary somatosensory (SI) and motor (M1) cortices on motor-evoked potentials (MEPs) and short-latency afferent inhibition (SAI). MEPs and SAI were recorded from the first dorsal interosseous (FDI) muscle of the right hand following 30Hz cTBS over left-hemisphere SI and M1 delivered to the same participants in separate sessions. Measurements were taken before and up to 60min following cTBS. CTBS over M1 suppressed MEPs and did not alter SAI. In contrast cTBS over SI facilitated MEPs and decreased median and digital nerve evoked SAI. These findings indicate that SAI amplitude is influenced by cTBS over SI but not M1, suggesting an important role for SI in the modulation of this circuit. These data provide further evidence that cTBS over SI versus M1 has opposite effects on corticospinal excitability. To date, plasticity-inducing TMS protocols delivered over M1 have failed to modulate SAI, and the present research continues to support these findings. However, in young adults, cTBS over SI acts to reduce SAI and simultaneously increase corticospinal excitability. Future studies may investigate the potential to modulate SAI via targeting neural activity within SI. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  11. A tryptamine derivative, SST-VEDI-1, inhibits apoptosis and stimulates mineralization in osteoblasts.

    PubMed

    Mikami, Yoshikazu; Somei, Masanori; Takagi, Minoru

    2009-01-01

    SST-VEDI-1(VEDI-1) is a new synthetic compound that is synthesized from tryptamine, and has structural similarity to the SSH-BM family of compounds. However, the biological effects of VEDI-1 have yet to be well characterized. A recent report has demonstrated that SSH-BM-type compounds can stimulate osteoblast activity in cultured scales of goldfish. In this study, we examined the effects of VEDI-1 on osteoblastic differentiation as well as its effects on apoptosis, which is known to be closely related to osteoblastic differentiation. We found that VEDI-1 enhanced the formation of mineralized nodules in rat osteoblast cell lines, including ROS17/2.8 cells, and in mouse pre-osteoblast cell lines, including MC3T3-E1 cells, in a dose dependent manner, which was accompanied by increased expression of late osteoblast markers, bone sialoprotein (BSP) and osteocalcin (OC). Furthermore, VEDI-I inhibited apoptotic cell death and regulated the expression of proteins in the Bcl-2 family. These results suggest that VEDI-1 may facilitate late differentiation of osteoblasts and may have an inhibitory effect on apoptosis.

  12. Cortical inhibition in attention deficit hyperactivity disorder: new insights from the electroencephalographic response to transcranial magnetic stimulation.

    PubMed

    Bruckmann, Sarah; Hauk, Daniela; Roessner, Veit; Resch, Franz; Freitag, Christine M; Kammer, Thomas; Ziemann, Ulf; Rothenberger, Aribert; Weisbrod, Matthias; Bender, Stephan

    2012-07-01

    Attention deficit hyperactivity disorder is one of the most frequent neuropsychiatric disorders in childhood. Transcranial magnetic stimulation studies based on muscle responses (motor-evoked potentials) suggested that reduced motor inhibition contributes to hyperactivity, a core symptom of the disease. Here we employed the N100 component of the electroencephalographic response to transcranial magnetic stimulation as a novel marker for a direct assessment of cortical inhibitory processes, which has not been examined in attention deficit hyperactivity disorder so far. We further investigated to what extent affected children were able to regulate motor cortical inhibition, and whether effects of age on the electroencephalographic response to transcranial magnetic stimulation were compatible with either a delay in brain maturation or a qualitatively different development. N100 amplitude evoked by transcranial magnetic stimulation and its age-dependent development were assessed in 20 children with attention deficit hyperactivity disorder and 19 healthy control children (8-14 years) by 64-channel electroencephalography. Amplitude and latency of the N100 component were compared at rest, during response preparation in a forewarned motor reaction time task and during movement execution. The amplitude of the N100 component at rest was significantly lower and its latency tended to be shorter in children with attention deficit hyperactivity disorder. Only in controls, N100 amplitude to transcranial magnetic stimulation was reduced by response preparation. During movement execution, N100 amplitude decreased while motor evoked potential amplitudes showed facilitation, indicating that the electroencephalographic response to transcranial magnetic stimulation provides further information on cortical excitability independent of motor evoked potential amplitudes and spinal influences. Children with attention deficit hyperactivity disorder showed a smaller N100 amplitude reduction

  13. The Impact of Full-Length, Trimeric and Globular Adiponectin on Lipolysis in Subcutaneous and Visceral Adipocytes of Obese and Non-Obese Women.

    PubMed

    Wedellova, Zuzana; Kovacova, Zuzana; Tencerova, Michaela; Vedral, Tomas; Rossmeislova, Lenka; Siklova-Vitkova, Michaela; Stich, Vladimir; Polak, Jan

    2013-01-01

    Contribution of individual adiponectin isoforms to lipolysis regulation remains unknown. We investigated the impact of full-length, trimeric and globular adiponectin isoforms on spontaneous lipolysis in subcutaneous abdominal (SCAAT) and visceral adipose tissues (VAT) of obese and non-obese subjects. Furthermore, we explored the role of AMPK (5'-AMP-activated protein kinase) in adiponectin-dependent lipolysis regulation and expression of adiponectin receptors type 1 and 2 (AdipoR1 and AdipoR2) in SCAAT and VAT. Primary adipocytes isolated from SCAAT and VAT of obese and non-obese women were incubated with 20 µg/ml of: A) full-length adiponectin (physiological mixture of all adiponectin isoforms), B) trimeric adiponectin isoform or C) globular adiponectin isoform. Glycerol released into media was used as a marker of lipolysis. While full-length adiponectin inhibited lipolysis by 22% in non-obese SCAAT, globular isoform inhibited lipolysis by 27% in obese SCAAT. No effect of either isoform was detected in non-obese VAT, however trimeric isoform inhibited lipolysis by 21% in obese VAT (all p<0.05). Trimeric isoform induced Thr172 p-AMPK in differentiated preadipocytes from a non-obese donor, while globular isoform induced Ser79 p-ACC by 32% (p<0.05) and Ser565 p-HSL by 52% (p = 0.08) in differentiated preadipocytes from an obese donor. AdipoR2 expression was 17% and 37% higher than AdipoR1 in SCAAT of obese and non-obese groups and by 23% higher in VAT of obese subjects (all p<0.05). In conclusion, the anti-lipolytic effect of adiponectin isoforms is modified with obesity: while full-length adiponectin exerts anti-lipolytic action in non-obese SCAAT, globular and trimeric isoforms show anti-lipolytic activity in obese SCAAT and VAT, respectively.

  14. Deep brain stimulation in the globus pallidus compensates response inhibition deficits: evidence from pantothenate kinase-associated neurodegeneration.

    PubMed

    Mückschel, Moritz; Smitka, Martin; Hermann, Andreas; von der Hagen, Maja; Beste, Christian

    2016-05-01

    Fronto-striatal loops are important for many cognitive control processes, like response inhibition, and it has been suggested that the globus pallidus is of particular importance for these processes. In the current study, we investigate the effect of deep brain stimulation in the GP on response inhibition processes by means of neurophysiological (EEG) methods. We perform a case-control study in neuroaxonal dystrophy pantothenate kinase-associated neurodegeneration (PKAN) using single-case statistics. We control the signal-to-noise ratio of the EEG data. The data show that disease-related changes in the globus pallidus lead to dysfunctions in response inhibition processes. Dysfunctions in the GP seem to affect controlled, but not automatized behavior as evidenced by an increased rate of false alarms and attenuation of inhibition-related neurophysiological correlates. With respect to controlled behavior in terms of response inhibition, it seems that pre-motor subprocesses and not evaluation subprocesses are affected. Deep brain stimulation in the globus pallidus seems to be able to compensate the effects of disease-related changes in this structure and normalizes response inhibition performance and their electrophysiological correlates in PKAN.

  15. Short-term effect of electrical nerve stimulation on spinal reciprocal inhibition during robot-assisted passive stepping in humans.

    PubMed

    Obata, Hiroki; Ogawa, Tetsuya; Kitamura, Taku; Masugi, Yohei; Takahashi, Miho; Kawashima, Noritaka; Nakazawa, Kimitaka

    2015-09-01

    The purpose of this study was to investigate the effect of electrical stimulation to the common peroneal nerve (CPN) on the spinal reflex and reciprocal inhibition (RI) during robot-assisted passive ground stepping (PGS) in healthy subjects. Five interventions were applied for 30 min in healthy subjects: PGS alone; strong CPN stimulation [50% of the maximal tibialis anterior (TA) M-wave, functional electrical stimulation (FES)] alone; weak CPN stimulation [just above the MT for the TA muscle, therapeutic electrical stimulation (TES)] alone; PGS with FES; and PGS with TES. FES and TES were applied intermittently to the CPN at 25 Hz. The soleus (Sol) H-reflex and RI, which was assessed by conditioning the Sol H-reflex with CPN stimulation, were investigated before (baseline), and 5, 15 and 30 min after each intervention. The amplitudes of the Sol H-reflex were not significantly different after each intervention as compared with the baseline values. The amounts of RI were significantly decreased 5 min after PGS with FES as compared with the baseline values, whereas they were significantly increased 5 and 15 min after PGS with TES. The other interventions did not affect the amount of RI. These results suggest that interventions that combined PGS with CPN stimulation changed the spinal RI in an intensity-dependent manner. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  16. Lipolysis and lipases in white adipose tissue - An update.

    PubMed

    Bolsoni-Lopes, Andressa; Alonso-Vale, Maria Isabel C

    2015-08-01

    Lipolysis is defined as the sequential hydrolysis of triacylglycerol (TAG) stored in cell lipid droplets. For many years, it was believed that hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) were the main enzymes catalyzing lipolysis in the white adipose tissue. Since the discovery of adipose triglyceride lipase (ATGL) in 2004, many studies were performed to investigate and characterize the actions of this lipase, as well as of other proteins and possible regulatory mechanisms involved, which reformulated the concept of lipolysis. Novel findings from these studies include the identification of lipolytic products as signaling molecules regulating important metabolic processes in many non-adipose tissues, unveiling a previously underestimated aspect of lipolysis. Thus, we present here an updated review of concepts and regulation of white adipocyte lipolysis with a special emphasis in its role in metabolism homeostasis and as a source of important signaling molecules.

  17. β-adrenoceptor blocking agents and lipolysis

    PubMed Central

    Harms, H. H.; De Vente, J.; Zaagsma, J.

    1982-01-01

    1 The pharmacological characteristics of β-adrenoceptor subtypes on adipocytes of various mammalian species, including man, are reviewed. 2 Rat adipocytes possess a homogeneous population of β-adrenoceptors with properties that clearly distinguish them from `classic' β1- and β2-adrenoceptors, although they share certain features with both. Thus, rat adipocyte β-adrenoceptors should be considered as non-β1-non-β2 receptors, like the atypical β-adrenoceptors found on erythrocytes of turkey, chicken and frog. 3 Preliminary data suggest that adipocyte β-adrenoceptors of guinea pig and swine are different from `classic' β1- and β2-adrenoceptors as well, whereas in the dog and possibly in the cat, a mixture of β1- and β2-receptors mediates catecholamine induced lipolysis. 4 Human adipocyte β-adrenoceptors probably also consist of at least two subtypes. Insufficient data are available to decide if these β-adrenoceptors are identical with `classic' β1- and β2-receptors, or share some hybrid characteristics with rat adipocyte β-adrenoceptors. 5 In vivo studies in animals as well as in man, tend to corroborate in vitro results. Cardioselective β-adrenoceptor blocking agents, like atenolol, metoprolol and practolol are not as effective in blocking catecholamine induced lipolysis as non-cardioselective agents like propranolol and pindolol. The relatively low potency of cardioselective β-adrenoceptor blocking agents is found using either isoprenaline, adrenaline or exercise as the agonist, suggesting that β2-adrenoceptors are involved. On the other hand, cardioselective agents, though less effective than non-cardioselective compounds, have a significant inhibitory effect on catecholamine induced lipolysis at doses that have only minimal effect on other β2-adrenoceptor mediated responses, which argues for participation of β1-adrenoceptors. 6 Thus, human in vitro and in vivo data are consistent with, but not proof of the hypothesis that a mixture of β1

  18. Intraportal Infusion of Ghrelin Could Inhibit Glucose-Stimulated GLP-1 Secretion by Enteric Neural Net in Wistar Rat

    PubMed Central

    Zhang, Xiyao; Li, Wensong; Li, Ping; Chang, Manli; Huang, Xu; Li, Qiang; Cui, Can

    2014-01-01

    As a regulator of food intake and energy metabolism, the role of ghrelin in glucose metabolism is still not fully understood. In this study, we determined the in vivo effect of ghrelin on incretin effect. We demonstrated that ghrelin inhibited the glucose-stimulated release of glucagon-like peptide-1 (GLP-1) when infused into the portal vein of Wistar rat. Hepatic vagotomy diminished the inhibitory effect of ghrelin on glucose-stimulated GLP-1 secretion. In addition, phentolamine, a nonselective α receptor antagonist, could recover the decrease of GLP-1 release induced by ghrelin infusion. Pralmorelin (an artificial growth hormone release peptide) infusion into the portal vein could also inhibit the glucose-stimulated release of GLP-1. And growth hormone secretagogue receptor antagonist, [D-lys3]-GHRP-6, infusion showed comparable increases of glucose stimulated GLP-1 release compared to ghrelin infusion into the portal vein. The data showed that intraportal infusion of ghrelin exerted an inhibitory effect on GLP-1 secretion through growth hormone secretagogue receptor 1α (GHS1α receptor), which indicated that the downregulation of ghrelin secretion after food intake was necessary for incretin effect. Furthermore, our results suggested that the enteric neural net involved hepatic vagal nerve and sympathetic nerve mediated inhibition effect of ghrelin on incretin effect. PMID:25247193

  19. Nuclear factor of activated T cell (NFAT) transcription proteins regulate genes involved in adipocyte metabolism and lipolysis

    SciTech Connect

    Holowachuk, Eugene W. . E-mail: geneh@telenet.net

    2007-09-21

    NFAT involvement in adipocyte physiological processes was examined by treatment with CsA and/or GSK3{beta} inhibitors (Li{sup +} or TZDZ-8), which prevent or increase NFAT nuclear translocation, respectively. CsA treatment reduced basal and TNF{alpha}-induced rates of lipolysis by 50%. Adipocytes preincubated with Li{sup +} or TZDZ-8 prior to CsA and/or TNF{alpha}, exhibited enhanced basal rates of lipolysis and complete inhibition of CsA-mediated decreased rates of lipolysis. CsA treatment dramatically reduced the mRNA levels of adipocyte-specific genes (aP2, HSL, PPAR{gamma}, ACS and Adn), compared with control or TNF{alpha}-treatment, whereas Li{sup +} pretreatment blocked the inhibitory effects of CsA, and mRNA levels of aP2, HSL, PPAR{gamma}, and ACS were found at or above control levels. NFAT nuclear localization, assessed by EMSA, confirmed that CsA or Li{sup +} treatments inhibited or increased NFAT nuclear translocation, respectively. These results show that NFAT proteins in mature adipocytes participate in the transcriptional control of genes involved in adipocyte metabolism and lipolysis.

  20. Muscarinic cholinergic inhibition of beta-adrenergic stimulation of phospholamban phosphorylation and CaS transport in guinea pig ventricles

    SciTech Connect

    Lindemann, J.P.; Watanabe, A.M.

    1985-10-25

    The effects of muscarinic cholinergic stimulation on beta-adrenergic induced increases in phospholamban phosphorylation and CaS transport were studied in intact myocardium. Isolated guinea pig ventricles were perfused via the coronary arteries with TSPi, after which membrane vesicles were isolated from individual hearts. Isoproterenol produced reversible increases in TSP incorporation into phospholamban. Associated with the increases in TSP incorporation were increases in the initial rate of phosphate-facilitated CaS uptake measured in aliquots of the same membrane vesicles isolated from the perfused hearts. The increases in TSP incorporation and calcium transport were significantly attenuated by the simultaneous administration of acetylcholine. Acetylcholine also attenuated increases in phospholamban phosphorylation and CaS uptake produced by the phosphodiesterase inhibitor isobutylmethylxanthine and forskolin. The contractile effects of all agents which increased cAMP levels (increased contractility and a reduction in the t1/2 of relaxation) were also attenuated by acetylcholine. The inhibitory effects of acetylcholine were associated with attenuation of the increases in cAMP levels produced by isoproterenol and isobutylmethylxanthine but not by forskolin. Acetylcholine also increased the rate of reversal of the functional and biochemical effects of isoproterenol by propranolol without affecting cAMP levels. These results suggest that cholinergic agonists inhibit the functional effects of beta-adrenergic stimulation in part by inhibition of phospholamban phosphorylation. This inhibition may be mediated by two potential mechanisms: inhibition of beta-adrenergic activation of adenylate cyclase and stimulation of dephosphorylation.

  1. Prefrontal hypoactivity associated with impaired inhibition in stimulant-dependent individuals but evidence for hyperactivation in their unaffected siblings.

    PubMed

    Morein-Zamir, Sharon; Simon Jones, P; Bullmore, Edward T; Robbins, Trevor W; Ersche, Karen D

    2013-09-01

    A neurocognitive endophenotype has been proposed for stimulant dependence, based on behavioral measures of inhibitory response control associated with white matter changes in the frontal cortex. This study investigated the functional neuroimaging correlates of inhibitory response control, as functional activity serves as a more dynamic measure than brain structure, allowing refinement of the suggested endophenotype. Stimulant-dependent individuals (SDIs), their unaffected siblings (SIBs), and healthy controls (CTs) performed the stop-signal task, including stop-signal reaction time (SSRT) as a measure of response inhibition, while undergoing functional magnetic resonance imaging. SDIs had impaired response inhibition accompanied by hypoactivation in the ventrolateral prefrontal cortex (PFC). In addition, they demonstrated hypoactivation in the anterior cingulate when failing to stop. In contrast, no hypoactivations were noted in their unaffected SIBs. Rather, they exhibited increased activation in the dorsomedial PFC relative to controls, together with inhibitory performance that was intermediate between that of the stimulant group and the healthy CT group. Such hyperactivations within the neurocircuitry underlying response inhibition and control are suggestive of compensatory mechanisms that could be protective in nature or could reflect coping with a pre-existing vulnerability, thus expressing potential aspects of resilience. The functional activation associated with response inhibition and error monitoring showed differential patterns of results between SDIs and their unaffected first-degree relatives, suggesting that the proposed endophenotype does not generalize to functional brain activity.

  2. Prefrontal Hypoactivity Associated with Impaired Inhibition in Stimulant-Dependent Individuals but Evidence for Hyperactivation in their Unaffected Siblings

    PubMed Central

    Morein-Zamir, Sharon; Simon Jones, P; Bullmore, Edward T; Robbins, Trevor W; Ersche, Karen D

    2013-01-01

    A neurocognitive endophenotype has been proposed for stimulant dependence, based on behavioral measures of inhibitory response control associated with white matter changes in the frontal cortex. This study investigated the functional neuroimaging correlates of inhibitory response control, as functional activity serves as a more dynamic measure than brain structure, allowing refinement of the suggested endophenotype. Stimulant-dependent individuals (SDIs), their unaffected siblings (SIBs), and healthy controls (CTs) performed the stop-signal task, including stop-signal reaction time (SSRT) as a measure of response inhibition, while undergoing functional magnetic resonance imaging. SDIs had impaired response inhibition accompanied by hypoactivation in the ventrolateral prefrontal cortex (PFC). In addition, they demonstrated hypoactivation in the anterior cingulate when failing to stop. In contrast, no hypoactivations were noted in their unaffected SIBs. Rather, they exhibited increased activation in the dorsomedial PFC relative to controls, together with inhibitory performance that was intermediate between that of the stimulant group and the healthy CT group. Such hyperactivations within the neurocircuitry underlying response inhibition and control are suggestive of compensatory mechanisms that could be protective in nature or could reflect coping with a pre-existing vulnerability, thus expressing potential aspects of resilience. The functional activation associated with response inhibition and error monitoring showed differential patterns of results between SDIs and their unaffected first-degree relatives, suggesting that the proposed endophenotype does not generalize to functional brain activity. PMID:23609131

  3. Further evidence for inhibition of episodic luteinizing hormone release in ovariectomized rats by stimulation of dopamine receptors.

    PubMed

    Drouva, S V; Gallo, R V

    1977-03-01

    Stimulation of dopamine receptors by apomorphine inhibits episodic LH release in ovariectomized rats. The present study was designed to examine further the role of dopamine in this process. Unrestrained, unanesthetized rats with indwelling right atrial cannulae were bled continuously (30 or 50 microliters of whole blood/5 min for 3-6 h) and whole blood samples analyzed for LH by radioimmunoassay. Animals were treated with various compounds reported to stimulate or block dopamine receptors. ET 495, a long acting dopamine receptor stimulating agent, caused a marked inhibition of episodic LH release (2 1/2-4 h). Control injections of distilled water had no effect. d-Butaclamol, a blocker of dopamine receptors, did not itself alter episodic LH release but prevented the inhibitory effects seen following apomorphine or ET 495. I-butaclamol, a biologically inactive form of butaclamol, had no effect. Measurement of plasma corticosterone levels in these same animals indicated increased values following apomorphine or ET 495 alone (when LH release was inhibited), as well as after apomorphine or ET 495 administration to d-butaclamol-pretreated rats (when LH levels did not change). These data support our previous hypothesis that in ovariectomized adult rats, activation of dopamine receptors is capable of inhibiting episodic LH release, but that dopamine may not play an inhibitory role under normal physiological conditions in the modulation of LH secretion. In addition, the inhibitory action of apomorphine and ET 495 does not appear to be exerted via a stress-induced release of adrenal corticosterone.

  4. Obestatin inhibits lipogenesis and glucose uptake in isolated primary rat adipocytes.

    PubMed

    Pruszynska-Oszmalek, E; Szczepankiewicz, D; Hertig, I; Skrzypski, M; Sassek, M; Kaczmarek, P; Kolodziejski, P A; Mackowiak, P; Nowak, K W; Strowski, M Z; Wojciechowicz, T

    2013-01-01

    Ghrelin and obestatin are encoded by the preproghrelin gene and originate from post-translational processing of the preproghrelin peptide. Obestatin is mainly present in the stomach, but its action is focused on appetite inhibition in opposition to ghrelin function. Recently, it has been presented that obestatin may regulate adipocyte metabolism and influence fat content. However, obestatin action is still poorly understood. Therefore, we aimed to investigate obestatin function on adipocyte metabolism in the rat. We studied changes in the mRNA expression of active and inactive isoforms of obestatin receptors. In addition, we analyzed influence of obestatin on lipogenesis, lipolysis and glucose transport in isolated adipocytes. Moreover, we also performed analysis of obestatin action on lipolysis in differentiated rat preadipocytes with silenced obestatin receptor. We found significantly higher expression of the obestatin receptor Gpr39-1a active form at an mRNA level following adipocytes incubation with obestatin. We did not observe expression changes in the inactive form of obestatin receptor Gpr39-1b. Additionally, we found significant changes in Gpr39-1a expression following obestatin receptor silencing in cells incubated with obestatin in comparison to control. Obestatin inhibited both, basal and insulin-stimulated lipogenesis and glucose transport in adipocytes. Furthermore, obestatin potentiated adrenalin-stimulated lipolysis. We also found reduced glycerol release following obestatin incubation in adipocytes with silenced Gpr39 gene. Our results indicate that obestatin acts via the GPR39 receptor in isolated adipocytes, and that through this mechanism obestatin influences lipid accumulation, glucose uptake and lipolysis.

  5. The Effects of Frequency-Dependent Dynamic Muscle Stimulation on Inhibition of Trabecular Bone Loss in a Disuse Model

    PubMed Central

    Lam, Hoyan; Qin, Yi-Xian

    2008-01-01

    Clinical electrical muscle stimulation has been shown to alleviate muscle atrophy resulting from functional disuse, yet little is known about its effect on the skeleton. The objective of this study is to evaluate the potential of dynamic muscle stimulation on disused trabecular bone, and to investigate the importance of optimized stimulation frequency in the loading regimen. Fifty-six skeletally mature Sprague-Dawley rats were divided into seven groups for the 4-week experiment: baseline control, age-matched control, hindlimb suspended (HLS), and HLS with muscle stimulation at 1 Hz, 20 Hz, 50 Hz, and 100 Hz. Muscle stimulation was carried out for 10 minutes per day for 5 days per week, total of 4 weeks. The metaphyseal and epiphyseal trabecular regions of the distal femurs were analyzed with microcomputed tomography and histomorphometry methods. HLS alone for 4-week resulted in a significant amount of trabecular bone loss and structural deterioration. Muscle contraction at 1 Hz was not sufficient to inhibit trabecular bone loss and resulted in similar amount of loss to that of HLS alone. Bone quantity and structure were significantly improved by applying muscle stimulation at mid-frequency (20 Hz & 50 Hz). Dynamic stimulation at 50 Hz demonstrated the greatest preventive effect on the skeleton against functional disused alone animals (up to +147% in bone volume fraction, +38% in trabecular number and -36% in trabecular separation). Histomorphometric analysis showed that the stimulation, regardless of its frequency, did not have an effect on the bone formation indices, such as mineral apposition rate and bone formation rate. Overall, the data demonstrated the potentials of frequency-dependent dynamic muscle contraction in regulating skeletal adaptive responses under disuse conditions. Dynamic muscle stimulation, with a specific regimen, may be beneficial to future orthopedic research in developing a countermeasure for disuse osteopenia and osteoporosis. PMID

  6. Baicalin Inhibits Inflammatory Responses to Interleukin-1β Stimulation in Human Chondrocytes.

    PubMed

    Xing, Deguo; Gao, Hongwei; Liu, Zhonghao; Zhao, Yangyang; Gong, Mingzhi

    2017-09-01

    A mix of flavonoids comprising baicalin (BA) and catechin showed effective impacts on controlling the progress of knee osteoarthritis (OA). However, little is known about the underlying mechanisms. The influences of BA on the transcriptional levels of a series of proinflammatory genes were measured using real-time reverse transcription and polymerase chain reaction (RT-PCR). The expressions of proteins involved in nuclear factor-κB (NF-κB) activation were detected by Western blot. The in vitro results were confirmed in a mouse OA model. We found that BA treatment led to remarkable reductions of OA-related proinflammatory gene expressions, including interleukin (IL)-6, tumor necrosis factor (TNF), chemokine (C-X-C motif) ligand 1 (CXCL1), and CXCL10. The transcriptional levels of inducible nitric oxide synthase (iNOS/Nos2), matrix metalloproteinases (MMP)3, and MMP13 were significantly inhibited by BA. We measured the productions of nitrite and prostaglandin E2 from human chondrocytes and BA was shown to reduce their productions. On the contrary, mRNA levels of aggrecan and collagen-II were enhanced by BA treatment. The inhibitory role of BA on OA may possibly be mediated by NF-κB signaling because of comparable decreases of phosphorylated (p)-p65 and p-IκBα and less p65 translocation in the nucleus after BA treatment. In OA mice model, BA significantly reduced synovitis scores and related gene expressions, including IL-6, TNF, CXCL1, CXCL10, MMP3, MMP13, and Nos2. In conclusion, BA suppresses the inflammatory responses of human chondrocytes to IL-1β stimulation, and NF-κB signaling may be involved in the mechanisms of BA functions.

  7. Inhibition of DYRK1A Stimulates Human β-Cell Proliferation.

    PubMed

    Dirice, Ercument; Walpita, Deepika; Vetere, Amedeo; Meier, Bennett C; Kahraman, Sevim; Hu, Jiang; Dančík, Vlado; Burns, Sean M; Gilbert, Tamara J; Olson, David E; Clemons, Paul A; Kulkarni, Rohit N; Wagner, Bridget K

    2016-06-01

    Restoring functional β-cell mass is an important therapeutic goal for both type 1 and type 2 diabetes (1). While proliferation of existing β-cells is the primary means of β-cell replacement in rodents (2), it is unclear whether a similar principle applies to humans, as human β-cells are remarkably resistant to stimulation of division (3,4). Here, we show that 5-iodotubercidin (5-IT), an annotated adenosine kinase inhibitor previously reported to increase proliferation in rodent and porcine islets (5), strongly and selectively increases human β-cell proliferation in vitro and in vivo. Remarkably, 5-IT also increased glucose-dependent insulin secretion after prolonged treatment. Kinome profiling revealed 5-IT to be a potent and selective inhibitor of the dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) and cell division cycle-like kinase families. Induction of β-cell proliferation by either 5-IT or harmine, another natural product DYRK1A inhibitor, was suppressed by coincubation with the calcineurin inhibitor FK506, suggesting involvement of DYRK1A and nuclear factor of activated T cells signaling. Gene expression profiling in whole islets treated with 5-IT revealed induction of proliferation- and cell cycle-related genes, suggesting that true proliferation is induced by 5-IT. Furthermore, 5-IT promotes β-cell proliferation in human islets grafted under the kidney capsule of NOD-scid IL2Rg(null) mice. These results point to inhibition of DYRK1A as a therapeutic strategy to increase human β-cell proliferation.

  8. Acute exercise induces cortical inhibition and reduces arousal in response to visual stimulation in young children.

    PubMed

    Mierau, Andreas; Hülsdünker, Thorben; Mierau, Julia; Hense, Andreas; Hense, Johannes; Strüder, Heiko K

    2014-05-01

    Physical exercise is known to induce a range of transient or sustained psychophysiological effects including stress reduction and improvements in cognitive performance. Previous studies in the area have focused on adults and there has been little research on the relationship between physical exercise and brain function in young children. This study examined the relationship between cortical oscillations, arousal and cognitive performance following physical exercise in 5/6-year preschoolers. Participants completed two counterbalanced sessions of 45 min exercise or a control condition. Electroencephalography (EEG) was measured at rest with the eyes closed and the eyes open, as well as during cognitive performance in a task requiring attention and reaction speed. This was done before (PRE) and after (POST) each session once the participants' heart rate returned to within 10% of pre-exercise values. The percentage change in spectral power from PRE to POST (Δ) differed significantly between conditions. Specifically, Δ alpha-1 power differed significantly between exercise (+5%) and the control condition (-5.9%) with the eyes-open, but not with the eyes-closed. This effect did not significantly differ between cortical regions (i.e., it was global). Further, Δ beta-1 and Δ beta-2 power differed significantly between exercise (beta-1: -10.8%, beta-2: -23.8%) and the control condition (beta-1: -4.3%, beta-2: -5.3%) at frontal sites independent of visual input. Despite significant changes in resting state EEG, cognitive performance and task-related EEG remained unaffected by exercise. The results were interpreted to indicate cortical inhibition and attenuation of arousal in response to visual stimulation following exercise in young children.

  9. Oncostatin M stimulates proliferation, induces collagen production and inhibits apoptosis of human lung fibroblasts

    PubMed Central

    Scaffidi, Amelia K; Mutsaers, Steven E; Moodley, Yuben P; McAnulty, Robin J; Laurent, Geoffrey J; Thompson, Philip J; Knight, Darryl A

    2002-01-01

    Oncostatin M (OSM), a member of the interleukin-6 (IL-6) cytokine family, acts on a variety of cells and elicits diversified biological responses, suggesting potential roles in the regulation of cell survival, differentiation and proliferation.We have examined the effect of OSM on the regulation of human lung fibroblast proliferation, collagen production and spontaneous apoptosis. The proliferative effects of OSM (0.5 – 100 ng ml−1) were assessed using a MTS assay as well as [3H]-thymidine incorporation and cell counts at 24 and 48 h. Hydroxyproline was measured as an index of procollagen production by high pressure liquid chromotography (HPLC). Apoptosis was determined by annexin staining.OSM enhanced the mitotic activity of lung fibroblasts in a time and dose dependent manner. Maximum proliferation of 57% above control was observed after incubation for 48 h with 2 ng ml−1 OSM (P<0.05).Incubation with the mitogen activated protein kinase (MAPK) kinase inhibitor, PD98059 or the tyrosine kinase inhibitor, genestein both significantly reduced the mitogenic effect of OSM (P<0.05).In contrast, proliferation in response to OSM was not regulated by induction of cyclo-oxygenase and subsequent prostaglandin E2 (PGE2) release or by IL-6.OSM also stimulated fibroblasts to synthesize pro-collagen by a maximum of 35% above control levels after 48 h (P<0.05).OSM significantly inhibited the spontaneous apoptosis of fibroblasts at 24 and 48 h.These results provide evidence that OSM has pro-fibrotic properties and suggest that it may play a role in normal lung wound repair and fibrosis. PMID:12086989

  10. Pulmonary Surfactant Phosphatidylglycerol Inhibits Mycoplasma pneumoniae-stimulated Eicosanoid Production from Human and Mouse Macrophages*

    PubMed Central

    Kandasamy, Pitchaimani; Zarini, Simona; Chan, Edward D.; Leslie, Christina C.; Murphy, Robert C.; Voelker, Dennis R.

    2011-01-01

    Mycoplasma pneumoniae is a human pathogen causing respiratory infections that are also associated with serious exacerbations of chronic lung diseases. Membranes and lipoproteins from M. pneumoniae induced a 4-fold increase in arachidonic acid (AA) release from RAW264.7 and a 2-fold increase in AA release from primary human alveolar macrophages. The bacterial lipoprotein mimic and TLR2/1 agonist Pam3Cys and the TLR2/6 agonist MALP-2 produced effects similar to those elicited by M. pneumoniae in macrophages by inducing the phosphorylation of p38MAPK and p44/42ERK1/2 MAP kinases and cyclooxygenase-2 (COX-2) expression. M. pneumoniae induced the generation of prostaglandins PGD2 and PGE2 from RAW264.7 cells and thromboxane B2 (TXB2) from human alveolar macrophages. Anti-TLR2 antibody completely abolished M. pneumoniae-induced AA release and TNFα secretion from RAW264.7 cells and human alveolar macrophages. Disruption of the phosphorylation of p44/42ERK1/2 or inactivation of cytosolic phospholipase A2α (cPLA2α) completely inhibited M. pneumoniae-induced AA release from macrophages. The minor pulmonary surfactant phospholipid, palmitoyl-oleoyl-phosphatidylglycerol (POPG), antagonized the proinflammatory actions of M. pneumoniae, Pam3Cys, and MALP-2 by reducing the production of AA metabolites from macrophages. The effect of POPG was specific, insofar as saturated PG, and saturated and unsaturated phosphatidylcholines did not have significant effect on M. pneumoniae-induced AA release. Collectively, these data demonstrate that M. pneumoniae stimulates the production of eicosanoids from macrophages through TLR2, and POPG suppresses this pathogen-induced response. PMID:21205826

  11. Anodal transcranial direct current stimulation of the motor cortex induces opposite modulation of reciprocal inhibition in wrist extensor and flexor.

    PubMed

    Lackmy-Vallée, Alexandra; Klomjai, Wanalee; Bussel, Bernard; Katz, Rose; Roche, Nicolas

    2014-09-15

    Transcranial direct current stimulation (tDCS) is used as a noninvasive tool to modulate brain excitability in humans. Recently, several studies have demonstrated that tDCS applied over the motor cortex also modulates spinal neural network excitability and therefore can be used to explore the corticospinal control acting on spinal neurons. Previously, we showed that reciprocal inhibition directed to wrist flexor motoneurons is enhanced during contralateral anodal tDCS, but it is likely that the corticospinal control acting on spinal networks controlling wrist flexors and extensors is not similar. The primary aim of the study was to explore the effects of anodal tDCS on reciprocal inhibition directed to wrist extensor motoneurons. To further examine the supraspinal control acting on the reciprocal inhibition between wrist flexors and extensors, we also explored the effects of the tDCS applied to the ipsilateral hand motor area. In healthy volunteers, we tested the effects induced by sham and anodal tDCS on reciprocal inhibition pathways innervating wrist muscles. Reciprocal inhibition directed from flexor to extensor muscles and the reverse situation, i.e., reciprocal inhibition, directed from extensors to flexors were studied in parallel with the H reflex technique. Our main finding was that contralateral anodal tDCS induces opposing effects on reciprocal inhibition: it decreases reciprocal inhibition directed from flexors to extensors, but it increases reciprocal inhibition directed from extensors to flexors. The functional result of these opposite effects on reciprocal inhibition seems to favor wrist extension excitability, suggesting an asymmetric descending control onto the interneurons that mediate reciprocal inhibition.

  12. Adenosine (ADO) released during orthodromic stimulation of the frog sympathetic ganglion inhibits phosphatidylinositol turnover (PI) associated with synaptic transmission

    SciTech Connect

    Curnish, R.; Bencherif, M.; Rubio, R.; Berne, R.M.

    1986-03-05

    The authors have previously demonstrated that /sup 3/H-purine release was enhanced during synaptic activation of the prelabelled frog sympathetic ganglion. In addition, during orthodromic stimulation, there is an increased /sup 3/H-inositol release (an index of PI) that occurs during the poststimulation period and not during the period of stimulation. They hypothesized that endogenous ADO inhibits PI turnover during orthodromic stimulation. To test this hypothesis (1) they performed experiments to directly measure ADO release in the extracellular fluid by placing the ganglion in a 5 ..mu..l drop of Ringer's and let it come to equilibrium with the interstitial fluid, (2) they destroyed endogenous ADO by suffusing adenosine deaminase (ADA) during the stimulation period. Their results show (1) orthodromic stimulation increases release of ADO into the bathing medium, (2) ADA induced an increase of PI during the stimulation period in contrast to an increase seen only during the poststimulation period when ADA was omitted. They conclude that there is dual control of PI during synaptic activity, a stimulatory effect (cause unknown) and a short lived inhibitory effect that is probably caused by adenosine.

  13. Effects of AMPK activation on lipolysis in primary rat adipocytes: studies at different glucose concentrations.

    PubMed

    Szkudelski, Tomasz; Szkudelska, Katarzyna

    2017-02-01

    Adipose tissue plays a key role in energy homeostasis. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an important intracellular energy sensor. Effects of activation of AMPK by aminomidazole-4-carboxamide ribonucleotide (AICAR) on lipolysis in the rat adipocytes were determined in the presence of 3 or 12 mM glucose. Response to epinephrine or dibutyryl-cAMP was higher in the presence of 12 mM glucose. AICAR decreased lipolysis, also when glucose was replaced by alanine or succinate and without decrease in cAMP levels. AICAR attenuated epinephrine-induced decrease in adenosine triphosphate (ATP) levels, reduced glucose uptake and lactate release. These results indicate that short-term activation of AMPK by AICAR in the rat adipocytes inhibits lipolysis, due to changes in the final, followed by protein kinase A (PKA), steps of the lipolytic cascade and improves intracellular energy status. Similar effects of AICAR were observed in the presence of 3 and 12 mM glucose, which indicates that the AMPK system is operative at high glucose concentrations.

  14. Ablation of a galectin preferentially expressed in adipocytes increases lipolysis, reduces adiposity, and improves insulin sensitivity in mice.

    PubMed

    Yang, Ri-Yao; Yu, Lan; Graham, James L; Hsu, Daniel K; Lloyd, K C Kent; Havel, Peter J; Liu, Fu-Tong

    2011-11-15

    The breakdown of triglycerides, or lipolysis, is a tightly controlled process that regulates fat mobilization in accord with an animal's energy needs. It is well established that lipolysis is stimulated by hormones that signal energy demand and is suppressed by the antilipolytic hormone insulin. However, much still remains to be learned about regulation of lipolysis by intracellular signaling pathways in adipocytes. Here we show that galectin-12, a member of a β-galactoside-binding lectin family preferentially expressed by adipocytes, functions as an intrinsic negative regulator of lipolysis. Galectin-12 is primarily localized on lipid droplets and regulates lipolytic protein kinase A signaling by acting upstream of phosphodiesterase activity to control cAMP levels. Ablation of galectin-12 in mice results in increased adipocyte mitochondrial respiration, reduced adiposity, and ameliorated insulin resistance/glucose intolerance. This study identifies unique properties of this intracellular galectin that is localized to an organelle and performs a critical function in lipid metabolism. These findings add to the significant functions exhibited by intracellular galectins, and have important therapeutic implications for human metabolic disorders.

  15. Ablation of a galectin preferentially expressed in adipocytes increases lipolysis, reduces adiposity, and improves insulin sensitivity in mice

    PubMed Central

    Yang, Ri-Yao; Yu, Lan; Graham, James L.; Hsu, Daniel K.; Lloyd, K. C. Kent; Havel, Peter J.; Liu, Fu-Tong

    2011-01-01

    The breakdown of triglycerides, or lipolysis, is a tightly controlled process that regulates fat mobilization in accord with an animal's energy needs. It is well established that lipolysis is stimulated by hormones that signal energy demand and is suppressed by the antilipolytic hormone insulin. However, much still remains to be learned about regulation of lipolysis by intracellular signaling pathways in adipocytes. Here we show that galectin-12, a member of a β-galactoside–binding lectin family preferentially expressed by adipocytes, functions as an intrinsic negative regulator of lipolysis. Galectin-12 is primarily localized on lipid droplets and regulates lipolytic protein kinase A signaling by acting upstream of phosphodiesterase activity to control cAMP levels. Ablation of galectin-12 in mice results in increased adipocyte mitochondrial respiration, reduced adiposity, and ameliorated insulin resistance/glucose intolerance. This study identifies unique properties of this intracellular galectin that is localized to an organelle and performs a critical function in lipid metabolism. These findings add to the significant functions exhibited by intracellular galectins, and have important therapeutic implications for human metabolic disorders. PMID:21969596

  16. Multichannel SEP-recording after paired median nerve stimulation suggests origin of paired-pulse inhibition rostral of the brainstem.

    PubMed

    Höffken, Oliver; Lenz, Melanie; Tegenthoff, Martin; Schwenkreis, Peter

    2010-01-14

    Paired-pulse techniques are a common tool to investigate the excitability of the cerebral cortex. Whereas in the motor system short interval intracortical inhibition assessed by paired-pulse transcranial magnetic stimulation clearly could be demonstrated to be generated within the motor cortex, the mechanism of paired-pulse inhibition measured over the somatosensory cortex after paired-pulse median nerve stimulation is less clear. The aim of this study was to further investigate the level of somatosensory processing where this paired-pulse inhibition is generated. We applied single and paired electrical stimulation of the median nerve with an interstimulus interval of 30ms. Somatosensory evoked potentials were recorded over the brachial plexus, the cranial cervical medulla and the primary somatosensory cortex. We analyzed peak-to-peak amplitudes evoked by the second stimulus of paired-pulse stimulation after digital subtraction of a single pulse (A2s), and referred it to the first response before linear subtraction (A1). Paired-pulse inhibition was expressed as a ratio (A2s/A1) of the amplitudes of the second (A2s) and the first (A1) peaks. We found a significant reduction of A2s as compared to A1 over S1, but no significant difference between A1 and A2s over brachial plexus and cranial medulla. In addition, the cortical amplitude ratio A2s/A1 was significantly reduced compared to the amplitude ratios over cranial medulla and brachial plexus. These results suggest that the underlying inhibitory mechanisms are generated rostral to the brainstem nuclei, probably due to the activity of thalamic or intracortical inhibitory interneurons. Copyright 2009 Elsevier Ireland Ltd. All rights reserved.

  17. Wogonin inhibits multiple myeloma-stimulated angiogenesis via c-Myc/VHL/HIF-1α signaling axis.

    PubMed

    Fu, Rong; Chen, Yan; Wang, Xiao-Ping; An, Teng; Tao, Lei; Zhou, Yu-Xin; Huang, Yu-Jie; Chen, Bao-An; Li, Zhi-Yu; You, Qi-Dong; Guo, Qing-Long; Wu, Zhao-Qiu

    2016-02-02

    Angiogenesis is associated with the progression of multiple myeloma (MM). Wogonin is an active mono-flavonoid with remarkable antitumor activity. However, its impact on MM-stimulated angiogenesis remains largely unknown. Here, we demonstrated that wogonin decreased expression and secretion of pro-angiogenic factors in MM cells via c-Myc/HIF-1α signaling axis, reducing MM-stimulated angiogenesis and MM cell proliferation in vivo. Overexpression of c-Myc in MM cells disrupted the balance between VHL SUMOylation and ubiquitination, and thus inhibited proteasome-mediated HIF-1α degradation. Impaired function of VHL ubiquitination complex in c-Myc-overexpressing cells was fully reversed by wogonin treatment via increasing HIF-1α-VHL interaction and promoting HIF-1α degradation. Collectively, our in vitro and in vivo studies reveal for the first time that wogonin represses MM-stimulated angiogenesis and tumor progression via c-Myc/VHL/HIF-1α signaling axis.

  18. Wogonin inhibits multiple myeloma-stimulated angiogenesis via c-Myc/VHL/HIF-1α signaling axis

    PubMed Central

    Wang, Xiao-Ping; An, Teng; Tao, Lei; Zhou, Yu-Xin; Huang, Yu-Jie; Chen, Bao-An; Li, Zhi-Yu; You, Qi-Dong; Guo, Qing-Long; Wu, Zhao-Qiu

    2016-01-01

    Angiogenesis is associated with the progression of multiple myeloma (MM). Wogonin is an active mono-flavonoid with remarkable antitumor activity. However, its impact on MM-stimulated angiogenesis remains largely unknown. Here, we demonstrated that wogonin decreased expression and secretion of pro-angiogenic factors in MM cells via c-Myc/HIF-1α signaling axis, reducing MM-stimulated angiogenesis and MM cell proliferation in vivo. Overexpression of c-Myc in MM cells disrupted the balance between VHL SUMOylation and ubiquitination, and thus inhibited proteasome-mediated HIF-1α degradation. Impaired function of VHL ubiquitination complex in c-Myc-overexpressing cells was fully reversed by wogonin treatment via increasing HIF-1α-VHL interaction and promoting HIF-1α degradation. Collectively, our in vitro and in vivo studies reveal for the first time that wogonin represses MM-stimulated angiogenesis and tumor progression via c-Myc/VHL/HIF-1α signaling axis. PMID:26735336

  19. Phorbol esters inhibit alpha/sub 1/-adrenergic receptor stimulated phosphoinositide hydrolysis and contraction in rat aorta

    SciTech Connect

    Not Available

    1986-03-01

    The mechanisms of pharmacomechanical coupling in vascular tissue are at the present time unclear. The authors and others have proposed that receptor-induced activation of phosphoinositide (PI) hydrolysis may be involved. To investigate this possibility they studied the actions of two biologically active phorbol esters: phorbol dibutyrate (PDB) and phorbol myristate diacetate (PMA) on receptor-stimulated PI hydrolysis in rat aortic rings. They found both PDB (IC/sub 5//sup 0/ approx. 5nM) and PMA (IC/sub 50/ approx. 30 nM) but not 4-..cap alpha..-phorbol (IC32%/sub 0/ > 10,000 nM) inhibited norepinephrine-stimulated PI hydrolysis. In the presence of the calcium channel antagonist nitrendipine, PDB potently inhibited both the phasic and tonic components of norepinephrine-induced vascular contraction. In the presence of 10/sup -7/M nitrendipine, PDB had an IC/sub 50/ for contraction of approximately 10nM. The results thus suggest a functional coupling between ..cap alpha../sub 1/-adrenergic receptor-stimulated PI hydrolysis and vascular contraction. The findings further imply a mode of feed-back regulation in vascular tissue involving phorbol ester and receptor-stimulated PI hydrolysis.

  20. The Ca2+ channel β subunit determines whether stimulation of Gq-coupled receptors enhances or inhibits N current

    PubMed Central

    Heneghan, John F.; Mitra-Ganguli, Tora; Stanish, Lee F.; Liu, Liwang; Zhao, Rubing

    2009-01-01

    In superior cervical ganglion (SCG) neurons, stimulation of M1 receptors (M1Rs) produces a distinct pattern of modulation of N-type calcium (N-) channel activity, enhancing currents elicited with negative test potentials and inhibiting currents elicited with positive test potentials. Exogenously applied arachidonic acid (AA) reproduces this profile of modulation, suggesting AA functions as a downstream messenger of M1Rs. In addition, techniques that diminish AA's concentration during M1R stimulation minimize N-current modulation. However, other studies suggest depletion of phosphatidylinositol-4,5-bisphosphate during M1R stimulation suffices to elicit modulation. In this study, we used an expression system to examine the physiological me