CB1 Receptor-Dependent and Independent Induction of Lipolysis in Primary Rat Adipocytes by the Inverse Agonist Rimonabant (SR141716A)

(1) Background: Acute administration of the cannabinoid receptor 1 (CB1R) inverse agonist Rimonabant (SR141716A) to fed Wistar rats was shown to elicit a rapid and short-lasting elevation of serum free fatty acids. (2) Methods: The effect of Rimonabant on lipolysis in isolated primary rat adipocytes was studied to raise the possibility for direct mechanisms not involving the (hypothalamic) CB1R. (3) Results: Incubation of these cells with Rimonabant-stimulated lipolysis to up to 25% of the maximal isoproterenol effect, which was based on both CB1R-dependent and independent mechanisms. The CB1R-dependent one was already effective at Rimonabant concentrations of less than 1 µM and after short-term incubation, partially additive to β-adrenergic agonists and blocked by insulin and, in part, by adenosine deaminase, but not by propranolol. It was accompanied by protein kinase A (PKA)-mediated association of hormone-sensitive lipase (HSL) with lipid droplets (LD) and dissociation of perilipin-1 from LD. The CB1R-independent stimulation of lipolysis was observed only at Rimonabant concentrations above 1 µM and after long-term incubation and was not affected by insulin. It was recapitulated by a cell-free system reconstituted with rat adipocyte LD and HSL. Rimonabant-induced cell-free lipolysis was not affected by PKA-mediated phosphorylation of LD and HSL, but abrogated by phospholipase digestion or emulsification of the LD. Furthermore, LD isolated from adipocytes and then treated with Rimonabant (>1 µM) were more efficient substrates for exogenously added HSL compared to control LD. The CB1R-independent lipolysis was also demonstrated in primary adipocytes from fed rats which had been treated with a single dose of Rimonabant (30 mg/kg). (4) Conclusions: These data argue for interaction of Rimonabant (at high concentrations) with both the LD surface and the CB1R of primary rat adipocytes, each leading to increased access of HSL to LD in phosphorylation-independent and dependent fashion, respectively. Both mechanisms may lead to direct and acute stimulation of lipolysis at peripheral tissues upon Rimonabant administration and represent targets for future obesity therapy which do not encompass the hypothalamic CB1R.

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Effects of cannabinoid and vanilloid receptor agonists and their interaction on learning and memory in rats

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2016-0274 ◽

2017 ◽

Vol 95 (4) ◽

pp. 382-387 ◽

Cited By ~ 9

Author(s):

Mariam Shiri ◽

Alireza Komaki ◽

Shahrbanoo Oryan ◽

Masoumeh Taheri ◽

Hamidreza Komaki ◽

...

Keyword(s):

Learning And Memory ◽

Cannabinoid Receptor ◽

Vanilloid Receptor ◽

Interactive Effects ◽

Control Group ◽

Acute Administration ◽

Male Wistar Rats ◽

Agonistic Effect ◽

Stimulation Of

Despite previous findings on the effects of cannabinoid and vanilloid systems on learning and memory, the effects of the combined stimulation of these 2 systems on learning and memory have not been studied. Therefore, in this study, we tested the interactive effects of cannabinoid and vanilloid systems on learning and memory in rats by using passive avoidance learning (PAL) tests. Forty male Wistar rats were divided into the following 4 groups: (1) control (DMSO+saline), (2) WIN55,212–2, (3) capsaicin, and (4) WIN55,212–2 + capsaicin. On test day, capsaicin, a vanilloid receptor type 1 (TRPV1) agonist, or WIN55,212–2, a cannabinoid receptor (CB1/CB2) agonist, or both substances were injected intraperitoneally. Compared to the control group, the group treated with capsaicin (TRPV1 agonist) had better scores in the PAL acquisition and retention test, whereas treatment with WIN55,212–2 (CB1/CB2 agonist) decreased the test scores. Capsaicin partly reduced the effects of WIN55,212–2 on PAL and memory. We conclude that the acute administration of a TRPV1 agonist improves the rats’ cognitive performance in PAL tasks and that a vanilloid-related mechanism may underlie the agonistic effect of WIN55,212–2 on learning and memory.

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Stimulation of protein and plasma albumin synthesis in a cell-free system from livers of nephrotic rats

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(62)90229-2 ◽

1962 ◽

Vol 8 (1-2) ◽

pp. 28-32 ◽

Cited By ~ 16

Author(s):

George A. Braun ◽

Julian B. Marsh ◽

David L. Drabkin

Keyword(s):

Albumin Synthesis ◽

Plasma Albumin ◽

Free System ◽

Cell Free System ◽

A Cell ◽

Stimulation Of

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DINITROCRESOL AND PHOSPHATE STIMULATION OF THE OXYGEN CONSUMPTION OF A CELL-FREE OXIDATIVE SYSTEM OBTAINED FROM SEA URCHIN EGGS

The Journal of General Physiology ◽

10.1085/jgp.32.4.503 ◽

1949 ◽

Vol 32 (4) ◽

pp. 503-509 ◽

Cited By ~ 10

Author(s):

Robert K. Crane ◽

Anna K. Keltch

Keyword(s):

Oxygen Consumption ◽

Sea Urchin ◽

Rabbit Kidney ◽

Free System ◽

Cell Free System ◽

Sea Urchin Eggs ◽

Equivalent Quantity ◽

A Cell ◽

Oxidative System ◽

Stimulation Of

1. A cell-free system capable of using oxygen with oxalacetate as substrate has been prepared from both unfertilized and fertilized sea urchin eggs. The oxygen uptake by this system is about twice that of an equivalent quantity of intact unfertilized eggs and half that of an equivalent quantity of intact fertilized eggs. 2. The oxygen consumption of this cell-free oxidative system can be stimulated by addition of suitable concentrations of 4,6-dinitro-o-cresol or by inorganic phosphate. This confirms, with a cell-free system obtained from sea urchin eggs, the observations of Loomis and Lipmann regarding stimulation of oxygen consumption by a system obtained from rabbit kidney. 3. A preliminary but unsuccessful attempt has been made to determine the conditions under which cell-free, aerobic, phosphorylating systems may be obtained from either unfertilized or fertilized sea urchin eggs.

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Characterization of the vasorelaxation to methanandamide in rat gastric arteries

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y06-058 ◽

2006 ◽

Vol 84 (11) ◽

pp. 1121-1132 ◽

Cited By ~ 7

Author(s):

Joke Breyne ◽

Johan Van de Voorde ◽

Bert Vanheel

Keyword(s):

Smooth Muscle ◽

Cannabinoid Receptors ◽

Cannabinoid Receptor ◽

Relaxant Effect ◽

High K ◽

Calcitonin Gene ◽

Perivascular Nerves ◽

High Concentrations ◽

Stimulation Of

In the present study, the relaxant effect of the cannabinoid methanandamide was explored in rat gastric arteries. Since in some vessels cannabinoids have been shown to release calcitonin gene-related peptide (CGRP) from perivascular nerves, the influence of methanandamide was compared with that of exogenous CGRP. Methanandamide and CGRP elicited concentration-dependent, endothelium-independent relaxations. Methanandamide-induced relaxations were unaffected by the CB1 receptor antagonist AM251, the CB2 receptor antagonists AM630 and SR144528, and combined pre-exposure to AM251 and SR144528. Pre-exposure to O-1918, an antagonist of a novel nonCB1/nonCB2 cannabinoid receptor, did not influence the relaxations to methanandamide. Capsaicin or capsazepine treatment slightly inhibited methanandamide-induced relaxations. Preincubation with 30 mmol/L extracellular K+ or 3 mmol/L TEA had no significant effect on the responses elicited by methanandamide, but reduced CGRP-induced relaxations. Relaxation to 10−5 mol/L methanandamide was significantly blunted by Bay K8644 and by preincubation with nifedipine. Furthermore, 10−5 mol/L methanandamide significantly inhibited CaCl2-induced contractions in norepinephrine-stimulated vessels previously depleted of intra- and extracellular Ca2+. Finally, preincubation with 10−5 mol/L methanandamide almost completely abolished high K+-induced contractions. These findings suggest that the vasorelaxant action of methanandamide in rat gastric arteries is not mediated by stimulation of known cannabinoid receptors and only partly related to stimulation of TRPV1 receptors on perivascular nerves. At high concentrations, methanandamide might induce relaxation by reducing calcium entry into the smooth muscle cells.

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Biosynthesis of heparin. Modulation of polysaccharide chain length in a cell-free system

Biochemical Journal ◽

10.1042/bj2540571 ◽

1988 ◽

Vol 254 (2) ◽

pp. 571-578 ◽

Cited By ~ 22

Author(s):

K Lidholt ◽

J Riesenfeld ◽

K G Jacobsson ◽

D S Feingold ◽

U Lindahl

Keyword(s):

Competitive Inhibition ◽

Alkali Treatment ◽

Polymerization Reaction ◽

Chain Elongation ◽

Free System ◽

Polysaccharide Chain ◽

Predominant Component ◽

A Cell ◽

Final Length ◽

High Concentrations

The formation of heparin-precursor polysaccharide (N-acetylheparosan) was studied with a mouse mastocytoma microsomal fraction. Incubation of this fraction with UDP-[3H]GlcA and UDP-GlcNAc yielded labelled macromolecules that could be depolymerized, apparently to single polysaccharide chains, by alkali treatment, and thus were assumed to be proteoglycans. Label from UDP-[3H]GlcA (approx. 3 microM) is transiently incorporated into microsomal polysaccharide even in the absence of added UDP-GlcNAc, probably owing to the presence of endogenous sugar nucleotide. When the concentration of exogenous UDP-GlcNAc was increased to 25 microM the rate of incorporation of 3H increased and proteoglycans carrying polysaccharide chains with an Mr of approx. 110,000 were produced. Increasing the UDP-GlcNAc concentration to 5 mM led to an approx. 4-fold decrease in the rate of 3H incorporation and a decrease in the Mr of the resulting polysaccharide chains to approx. 6000 (predominant component). When both UDP-GlcA and UDP-GlcNAc were present at high concentrations (5 mM) the rate of polymerization and the polysaccharide chain size were again increased. The results suggest that the inhibition of polymerization observed at grossly different concentrations of the two sugar nucleotides, UDP-GlcA and UDP-GlcNAc, may be due either to interference with the transport of one of these precursors across the Golgi membrane or to competitive inhibition of one of the glycosyltransferases. The maximal rate of chain elongation obtained, under the conditions employed, was about 40 disaccharide units/min. The final length of the polysaccharide chains was directly related to the rate of the polymerization reaction.

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Translocation of Hormone-sensitive Lipase and Perilipin upon Lipolytic Stimulation of Rat Adipocytes

Journal of Biological Chemistry ◽

10.1074/jbc.275.7.5011 ◽

2000 ◽

Vol 275 (7) ◽

pp. 5011-5015 ◽

Cited By ~ 175

Author(s):

Gary M. Clifford ◽

Constantine Londos ◽

Fredric B. Kraemer ◽

Richard G. Vernon ◽

Stephen J. Yeaman

Keyword(s):

Hormone Sensitive Lipase ◽

Rat Adipocytes ◽

Hormone Sensitive ◽

Stimulation Of

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The posttranslational processing of ras p21 is critical for its stimulation of yeast adenylate cyclase.

Molecular and Cellular Biology ◽

10.1128/mcb.12.10.4515 ◽

1992 ◽

Vol 12 (10) ◽

pp. 4515-4520 ◽

Cited By ~ 29

Author(s):

H Horiuchi ◽

K Kaibuchi ◽

M Kawamura ◽

Y Matsuura ◽

N Suzuki ◽

...

Keyword(s):

Adenylate Cyclase ◽

Target Protein ◽

Yeast Cells ◽

Posttranslational Processing ◽

Ras Gene ◽

Free System ◽

Ras Genes ◽

A Cell ◽

Ras P21 ◽

Stimulation Of

Mammalian ras genes substitute for the yeast RAS gene, and their products activate adenylate cyclase in yeast cells, although the direct target protein of mammalian ras p21s remains to be identified. ras p21s undergo posttranslational processing, including prenylation, proteolysis, methylation, and palmitoylation, at their C-terminal regions. We have previously reported that the posttranslational processing of Ki-ras p21 is essential for its interaction with one of its GDP/GTP exchange proteins named smg GDS. In this investigation, we have studied whether the posttranslational processing of Ki- and Ha-ras p21s is critical for their stimulation of yeast adenylate cyclase in a cell-free system. We show that the posttranslationally fully processed Ki- and Ha-ras p21s activate yeast adenylate cyclase far more effectively than do the unprocessed proteins. The previous and present results suggest that the posttranslational processing of ras p21s is important for their interaction not only with smg GDS but also with the target protein.

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