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Leroux M, Lemery T, Boulet N, Briot A, Zakaroff A, Bouloumié A, Andrade F, Pérez-Matute P, Arbones-Mainar JM, Carpéné C. Effects of the amino acid derivatives, β-hydroxy-β-methylbutyrate, taurine, and N-methyltyramine, on triacylglycerol breakdown in fat cells. J Physiol Biochem 2019; 75:263-273. [PMID: 30919256 DOI: 10.1007/s13105-019-00677-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/15/2019] [Indexed: 01/28/2023]
Abstract
Various amino acid (AA) metabolites are used as supplements to facilitate metabolic control and enhance responsiveness of insulin-sensitive tissues. β-hydroxy-β-methylbutyrate (HMB) is a leucine metabolite proposed to prevent muscle wasting and to mitigate insulin resistance. Taurine, commonly added to energizing drinks, is a metabolite of methionine and cysteine present in bile juice, and proposed to be involved in lipid digestion and to be pro-lipolytic in adipocytes. N-methyltyramine (NMT) is a phenylalanine metabolite found in orange juices at 0.1-3 ppm while its effects on lipid mobilization remain controversial. Here, the putative lipolytic effects of these AA metabolites were studied and it was tested whether they could enhance insulin antilipolytic response in adipocytes. Release of glycerol and non-esterified fatty acids (NEFAs) was measured after a 2-h incubation of adipocytes obtained from control and diet-induced obese mice or from obese patients. In mouse, none of the tested AA derivatives was lipolytic from 1 μM to 1 mM. These compounds did not improve insulin antilipolytic effect or isoprenaline lipolytic action, except for 1 mM NMT that impaired triacylglycerol breakdown in obese mice. In human adipocytes, HMB and taurine were not lipolytic, while NMT weakly activated glycerol and NEFA release at 1 mM. However, 100 μM NMT impaired isoprenaline-stimulated lipolysis in a manner that was hardly added to insulin antilipolytic effect. Since none of these AA derivatives acutely helped or replaced insulin antilipolytic effect in adipocytes, the present in vitro observations do not support their proposed insulin-sensitizing properties. Moreover, NMT, HMB, and taurine were not notably lipolytic.
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Affiliation(s)
- Mélanie Leroux
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Tristan Lemery
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Nathalie Boulet
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Anaïs Briot
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Alexia Zakaroff
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Anne Bouloumié
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France.,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France
| | - Fernando Andrade
- Metabolomics Platform, BioCruces Bizkaia Health Research Institute, linked clinical group of Rare Diseases CIBER (CIBERER), Barakaldo, Spain
| | - Patricia Pérez-Matute
- Infectious Diseases Department, Center for Biomedical Research of La Rioja (CIBIR), Logroño, Spain
| | - Jose M Arbones-Mainar
- Adipocyte and Fat Biology Laboratory, Instituto Aragonés de Ciencias de la Salud (IACS), Instituto de Investigación Sanitaria (IIS) Aragón. Zaragoza, Spain. CIBER Fisiopatología Obesidad y Nutrición (CIBERObn), Instituto Salud Carlos III, Madrid, Spain
| | - Christian Carpéné
- Institute of Metabolic and Cardiovascular Diseases, INSERM, UMR1048, Team 1, I2MC, CHU Rangueil, BP84225, 1 avenue Jean Poulhès, 31432, Toulouse cedex 4, France. .,University of Toulouse, Paul Sabatier University, UMR1048, Toulouse, France.
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Gómez-Ambrosi J, Frühbeck G, Martínez JA. Interactions between an alpha2-adrenergic antagonist and a beta3-adrenergic agonist on the expression of UCP2 and UCP3 in rats. J Physiol Biochem 2002; 58:17-23. [PMID: 12222743 DOI: 10.1007/bf03179834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This experimental trial was devised to assess whether selective beta3-adrenergic receptor (AR) stimulation and simultaneous blockade of alpha2-AR would affect thermoregulation. With this purpose, the individual and combined administration of a beta-AR agonist, trecadrine, and an alpha2-AR antagonist, yohimbine, were evaluated. Yohimbine produced a marked decrease (p < 0.001) in body temperature one hour after administration (5 mg kg(-1), i.p.) and blocked the thermogenic effect of trecadrine (1 mg kg(-1), i.p.) when simultaneously administered. Uncoupling protein-2 expression in skeletal muscle was downregulated (p < 0.05) by trecadrine, while yohimbine had no effect. White adipose tissue UCP2 and muscle UCP3 were not modified by either trecadrine or yohimbine administration. Liver UCP2 mRNA expression was significantly decreased by yohimbine (p < 0.05). However, this downregulation does not seem to explain the reduction in temperature produced by yohimbine given the fact that trecadrine produced a similar downregulation of hepatic UCP2 (p < 0.05). The present work indicates that alpha2-AR antagonism blocks the thermogenic effects mediated by beta3-AR stimulation, contrary to our expectations, suggesting a possible interplay between both mechanisms. Moreover, these effects are not apparently explained by changes in UCP2 and UCP3.
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Affiliation(s)
- J Gómez-Ambrosi
- Departamento de Fisiología y Nutricion, Universidad de Navarra, Spain
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Gasic S, Green A. Gi down-regulation and heterologous desensitization in adipocytes after treatment with the alpha 2-agonist UK 14304. Biochem Pharmacol 1995; 49:785-90. [PMID: 7702636 DOI: 10.1016/0006-2952(94)00537-v] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Prolonged treatment of rat adipocytes with the A1-adenosine receptor agonist [-]N(6)-phenylisopropyl adenosine (PIA) or prostaglandin E1 down-regulates Gi and induces heterologous desensitization. alpha 2-Adrenergic receptors also inhibit adenylyl cyclase through Gi, but whether alpha 2-receptors are present on rat adipocytes has been controversial. We have investigated the effects of the highly specific alpha 2-adrenergic agonist UK 14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline) on rat adipocytes. In previous studies on young rats, we were unable to demonstrate an effect of the alpha 2-agonist. We now report that, in cells isolated from older, more obese rats (300-400 g), UK 14304 inhibited lipolysis (measured as the rate of glycerol release) by approximately 40% (EC50 approximately 40 nM). To determine whether UK 14304 would induce heterologous desensitization, we incubated adipocytes with or without 1 microM UK 14304 for 4 days in primary culture. The cells were then washed, and the rate of lipolysis was determined during a 30-min incubation in the presence of various concentrations of PIA. The concentration-response curve for PIA-induced inhibition of lipolysis was shifted to the right, with the EC50 for UK 14304-treated cells about 2-fold higher than in the control cells. This finding demonstrates that the alpha 2-agonist can desensitize the response to PIA and indicates heterologous desensitization. To investigate the mechanism of this phenomenon, we isolated crude membrane fractions from the cells and analyzed them on Western blots using antibodies against Gi alpha 1, 2 and 3. In cells treated with UK 14304 for 4 days, Gi1 alpha and Gi2 alpha were down-regulated to about 15% of the control level, and Gi3 alpha was decreased to 30% of control. We conclude that prolonged treatment of adipocytes with the alpha 2-agonist induces heterologous desensitization of lipolysis and causes down-regulation of Gi. The findings suggest that G-protein down-regulation is a mechanism for heterologous desensitization.
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Affiliation(s)
- S Gasic
- Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-1060
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Giudicelli Y, Dieudonne MN, Lacasa D, Pasquier YN, Pecquery R. Modulation by sex hormones of the membranous transducing system regulating fatty acid mobilization in adipose tissue. Prostaglandins Leukot Essent Fatty Acids 1993; 48:91-100. [PMID: 8380933 DOI: 10.1016/0952-3278(93)90015-o] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This review summarizes recent animal studies performed to determine the possible role played by sex hormones in the sex- and site-related differences characterizing adipocyte lipolytic activity. In both normal female rats and male hamsters, fat cells from deep intra-abdominal sites elicit higher catecholamine-stimulated lipolytic responses than subcutaneous adipocytes. By using ovariectomized rats, it was found that estradiol 'in vivo', while having no effect in subcutaneous cells, promotes catecholamine-stimulated lipolysis in deep intraabdominal adipocytes by increasing their adenylate cyclase catalytic activity. By using castrated hamsters, it was found that both deep intra-abdominal and subcutaneous fat cell lipolytic activities are equally sensitive to testosterone. In these cells, testosterone treatment promotes not only the beta-adrenergic lipolytic responses by increasing both the adenylate cyclase catalytic activity and the Gs alpha level, but also enhances the alpha 2-adrenergic antilipolytic responses through a transcriptional activation of the alpha 2-adrenoceptor expression. These experiments demonstrate that in some, but not all, white adipocytes the adrenergic signal transducing system regulating lipolysis is a target for sex hormones. This finding may have potential importance in the understanding of the mechanisms underlying the sex-related regional specificities of adipose tissue metabolism and distribution.
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Affiliation(s)
- Y Giudicelli
- Laboratoire de biochimie, Faculté de Médecine Paris-Ouest, C.H.I. de Poissy, France
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Paulin A, Deshaies Y. Serum free fatty acids are not involved in acute exercise-induced reduction of LPL in rat tissues. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 262:E377-82. [PMID: 1566824 DOI: 10.1152/ajpendo.1992.262.4.e377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The present studies were designed to verify whether preventing the rise in serum levels of nonesterified fatty acids (NEFA) by adrenergic blockade would interfere with the decrease in tissue lipoprotein lipase (LPL) activity caused by acute exercise in rats. Ninety minutes before being killed, male rats were injected intraperitoneally with either saline, the beta-adrenergic blocker propranolol (25 mg/kg body weight), or the alpha 2-adrenergic blocker yohimbine (3 mg/kg body weight). Half of each group was killed at rest and the other half immediately after a 1-h run on a treadmill. LPL was determined in white adipose tissue (WAT), heart, and red vastus lateralis muscle (VLM). Exercise enhanced serum levels of NEFA 50% over resting values in saline-injected rats. The latter increase was totally abolished in animals having received propranolol or yohimbine. The activity of LPL in WAT, heart, and red VLM was approximately 35% lower in exercised rats than in resting animals. Serum triacylglycerols were also reduced by the run. Neither propranolol nor yohimbine interfered with any of these reductions. Exercise did not change serum glucose levels in saline-injected rats but decreased it in those injected with propranolol or yohimbine. Serum insulin was unchanged by exercise and by the antagonists. These findings suggest that the beta- and alpha 2-adrenergic pathways, as well as the exercise-induced rise in serum levels of NEFA, are not responsible for the early reducing effect of a 1-h run on tissue LPL activity in untrained rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Paulin
- Department of Physiology, School of Medicine, Laval University, Quebec, Canada
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Non-adrenergic sites for imidazolines are not directly involved in the alpha 2-adrenergic antilipolytic effect of UK 14304 in rat adipocytes. Biochem Pharmacol 1990; 40:437-45. [PMID: 1974423 DOI: 10.1016/0006-2952(90)90541-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The binding of the alpha 2-agonist [3H]UK 14304 on Wistar rat adipocyte membranes was separated in two distinct components: one was displaceable by adrenaline or other alpha 2-adrenergic agents and possessed the characteristics of alpha 2-adrenoceptors while the other, non-adrenergic in nature, was only recognized by some imidazoline derivatives [3H]idazoxan binding shared the same characteristics. The non-adrenergic sites labeled by both radioligands are similar to those described for [3H]idazoxan on other tissues such as brain cortex, smooth muscle and kidney. Even though they were about 10-fold more numerous than the true alpha 2-adrenoceptors, the non-adrenergic binding sites were not directly involved in the antilipolytic action of UK 14304 since alpha 2-antagonists devoid of interaction with these sites (yohimbine, phentolamine) totally blocked the UK 14304 effect. However, the existence of such a type of site impairs direct quantification of alpha 2-adrenoceptors in rat adipocytes. The use of [3H]RX 821002 (2-(2-methoxy-1,4-benzodioxan-2yl)imidazoline) allowed an accurate quantification of rat adipocyte alpha 2-adrenoceptors (Bmax = 35 +/- 2 fmol/mg protein, Kd = 2.6 +/- 0.6 nM) since it did not interact with non-adrenergic binding sites and exhibited the highest alpha 2-blocking properties among the various alpha 2-antagonists tested. [3H]RX 821002 binding analysis revealed that alpha 2-adrenoceptors are, on rat adipocytes; (i) less numerous than in other species well known for their alpha 2-adrenergic inhibitory regulation of lipolysis (human, hamster, rabbit); (ii) slightly different in nature from the receptors of these species since they had weaker affinity for clonidine and yohimbine; and however (iii) not of the typical alpha 2-B subtype since the affinity of prazosin was lower than that of oxymetazoline in displacing [3H]RX 821002 or [3H]yohimbine binding.
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