n-oleoylethanolamine and pirinixic-acid

The peroxisome proliferator-activated receptor alpha (PPARα) is a member of the nuclear receptor superfamily that has been suggested as a modulator of several physiological functions. The PPARα recognizes as an endogenous ligand the anorexic lipid mediator oleoylethanolamide (OEA) which displays wake-inducing properties. Despite that recent evidence indicates that activation of PPARα by synthetic agonists such as Wy14643 enhances waking as well as the extracellular contents of wake-related neurotransmitters, the role of PPARα in sleep recovery after prolonged waking has not been fully described. Thus, the aim of this study was to characterize if PPARα regulates sleep rebound after total sleep deprivation (TSD). We report that after 6h of TSD activation of PPARα by pharmacological systemic administration of OEA (10, 20 or 30mg/Kg, i.p.) promoted alertness by blocking the sleep rebound after TSD. Besides, wake-linked compounds such as dopamine, norepinephrine, serotonin, or adenosine collected from nucleus accumbens were enhanced after TSD in OEA-treated animals. These sleep and neurochemical results were mimicked after injection of PPARα agonist Wy14643 (10, 20, 30mg/Kg, i.p.). However, similar findings from the sham of vehicle groups were observed if PPARα antagonist MK-886 was administered to rats (10, 20, 30mg/Kg, i.p.). Our results strengthened the hypothesis that PPARα might modulate sleep and neurochemical homeostasis after sleep deprivation.

Topics: Adenosine; Animals; Biogenic Monoamines; Brain; Dose-Response Relationship, Drug; Endocannabinoids; Homeostasis; Indoles; Male; Oleic Acids; Peroxisome Proliferators; PPAR alpha; Pyrimidines; Rats, Wistar; Sleep; Sleep Deprivation; Wakefulness; Wakefulness-Promoting Agents

PPAR alpha is a ligand-activated transcription factor belonging to the nuclear receptor superfamily. PPAR alpha is involved in the regulation of in vivo triglyceride levels, presumably through its effects on fatty acid and lipoprotein metabolism. Some nuclear receptors have been involved in rapid effects mediated by non-genomic mechanisms. In this paper, we report the rapid non-genomic effects of PPAR alpha ligands on the intracellular calcium concentration ([Ca2+]i), mitochondrial function, reactive oxygen species (ROS) generation, and secretion of insulin in freshly isolated mouse islets of Langerhans. The hypolipidemic fibrate PPAR alpha agonist WY-14 643 decreased the glucose-induced calcium oscillations in intact islets. This effect was mimicked by the synthetic agonist GW7647 and the endogenous agonist oleylethanolamide. The WY-14 643 action was rapid in onset (5 min) and was still produced in the presence of protein and mRNA synthesis inhibitors, cycloheximide, and actinomycin-d. This suggests that it is independent of gene transcription. In addition, WY-14 623 impaired mitochondrial function, increased ROS formation and decreased insulin release. PPAR alpha is present in beta-cells, mainly in the cytosol and nucleus, with a small subpopulation localized in the plasma membrane. However, the presence of the PPAR alpha ligand effects in mice bearing a disrupted Ppar alpha gene raises the possibility that the rapid effects of the agonists in pancreatic beta-cells are independent of the receptor. We conclude that PPAR alpha agonists produce a decrease in glucose-induced [Ca2+]i signals and insulin secretion in beta-cells through a rapid, non-genomic mechanism.

Topics: Animals; Anticholesteremic Agents; Butyrates; Calcium; Insulin; Insulin Secretion; Insulin-Secreting Cells; Male; Mediator Complex Subunit 1; Mice; Mitochondria; Oleic Acids; Phenylurea Compounds; Pyrimidines; Reactive Oxygen Species; Transcription Factors

Oleoylethanolamide (OEA) is a lipid mediator belonging to the fatty acid ethanolamides family. It is produced by intestine and adipose tissue. It inhibits food intake and body weight gain, and has hypolipemiant action in vivo, as well as a lipolytic effect in vitro. OEA is a PPAR-alpha agonist, and recently it has been found that OEA is an endogenous ligand of an orphan receptor. Previously, we have shown that OEA inhibits insulin-stimulated glucose uptake in isolated adipocytes, and produces glucose intolerance in rats. In the present work, we have studied another insulin target cell, the hepatocyte using a rat hepatoma cell line (HTC), and we have studied the cross-talk of OEA signalling with metabolic and mitotic signal transduction of insulin receptor. OEA dose-dependently activates JNK and p38 MAPK, and inhibits insulin receptor phosphorylation. OEA inhibits insulin receptor activation, blunting insulin signalling in the downstream PI3K pathway, decreasing phosphorylation of PKB and its target GSK-3. OEA also inhibits insulin-dependent MAPK pathway, as assessed by immunoblot of phosphorylated MEK and MAPK. These effects were reversed by blocking JNK or p38 MAPK using pharmacological inhibitors (SP 600125, and SB 203580). Since OEA is an endogenous PPAR-alpha agonist, we investigated whether a pharmacologic agonist (WY 14643) may mimic the OEA effect on insulin receptor signalling. Activation of PPAR-alpha by the pharmacological agonist WY14643 in HTC hepatoma cells is sufficient to inhibit insulin signalling and this effect is also dependent on p38 MAPK but not JNK kinase. In summary, OEA inhibits insulin metabolic and mitogenic signalling by activation of JNK and p38 MAPK via PPAR-alpha.

Topics: Animals; Carcinoma, Hepatocellular; Cell Line; Dose-Response Relationship, Drug; Endocannabinoids; Enzyme Activation; JNK Mitogen-Activated Protein Kinases; Ligands; Liver Neoplasms; MAP Kinase Signaling System; Oleic Acids; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Phosphotyrosine; PPAR alpha; Pyrimidines; Rats; Receptor, Insulin; Signal Transduction

Oleoylethanolamide (OEA) is a natural fatty acid amide that mainly modulates feeding and energy homeostasis by binding to peroxisome proliferator-activated receptor-alpha (PPAR-alpha) [Rodríguez de Fonseca F, Navarro M, Gómez R, Escuredo L, Navas F, Fu J, et al. An anorexic lipid mediator regulated by feeding. Nature 2001;414:209-12; Fu J, Gaetani S, Oveisi F, Lo Verme J, Serrano A, Rodríguez de Fonseca F, et al. Oleoylethanolamide regulates feeding and body weight through activation of the nuclear receptor PPAR-alpha. Nature 2003;425:90-3]. Additionally, it has been proposed that OEA could act via other receptors, including the vanilloid receptor (TRPV1) [Wang X, Miyares RL, Ahern GP. Oleoylethanolamide excites vagal sensory neurones, induces visceral pain and reduces short-term food intake in mice via capsaicin receptor TRPV1. J Physiol 2005;564:541-7.] or the GPR119 receptor [Overton HA, Babbs AJ, Doel SM, Fyfe MC, Gardner LS, Griffin G, et al. Deorphanization of a G protein-coupled receptor for oleoylethanolamide and its use in the discovery of small-molecule hypophagic agents. Cell Metab 2006;3:167-175], suggesting that OEA might subserve other physiological roles, including pain perception. We have evaluated the effect of OEA in two types of nociceptive responses evoked by visceral and inflammatory pain in rodents. Our results suggest that OEA has analgesic properties reducing the nociceptive responses produced by administration of acetic acid and formalin in two experimental animal models. Additional research was performed to investigate the mechanisms underlying this analgesic effect. To this end, we evaluated the actions of OEA in mice null for the PPAR-alpha receptor gene and compared its actions with those of PPAR-alpha receptor wild-type animal. We also compared the effect of MK-801 in order to evaluate the role of NMDA receptor in this analgesia. Our data showed that OEA reduced visceral and inflammatory responses through a PPAR-alpha-activation independent mechanism. Co-administration of subanalgesic doses of MK-801 and OEA produced an analgesic effect, suggesting the participation of glutamatergic transmission in the antinociceptive effect of OEA. This study represents a novel approach to the examination of the effectiveness of OEA in nociceptive responses and provides a framework for understanding its biological functions and endogenous targets in visceral and inflammatory pain.

Topics: Analgesics; Animals; Anticholesteremic Agents; Behavior, Animal; Disease Models, Animal; Dizocilpine Maleate; Dose-Response Relationship, Drug; Drug Interactions; Endocannabinoids; Excitatory Amino Acid Antagonists; Exploratory Behavior; Inflammation; Male; Mice; Mice, Knockout; Morphine; Oleic Acids; Pain; Pain Measurement; PPAR gamma; Pyrimidines

The fatty-acid ethanolamide, oleoylethanolamide (OEA), is a naturally occurring lipid that regulates feeding and body weight [Rodriguez de Fonseca, F., Navarro, M., Gomez, R., Escuredo, L., Nava, F., Fu, J., Murillo-Rodriguez, E., Giuffrida, A., LoVerme, J., Gaetani, S., Kathuria, S., Gall, C., Piomelli, D., 2001. An anorexic lipid mediator regulated by feeding. Nature 414, 209-212], and serves as an endogenous agonist of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) [Fu, J., Gaetani, S., Oveisi, F., Lo Verme, J., Serrano, A., Rodriguez De Fonseca, F., Rosengarth., A., Luecke, H., Di Giacomo, B., Tarzia, G., Piomelli, D., 2003. Oleoylethanolamide regulates feeding and body weight through activation of the nuclear receptor PPAR-alpha. Nature 425, 90-93], a ligand-activated transcription factor that regulates several aspects of lipid metabolism [. Peroxisome proliferator-activated receptors: nuclear control of metabolism. Endocr. Rev. 20, 649-688]). OEA reduces food intake in wild-type mice, but not in mice deficient in PPAR-alpha (PPAR-alpha(-/-)), an effect that is also observed with the PPAR-alpha agonists Wy-14643 and GW7647 [Brown, P.J., Chapman, J.M., Oplinger, J.A., Stuart, L.W., Willson, T.M. and Wu, Z., 2000. Chemical compounds as selective activators of PPAR-alpha. PCT Int. Appl., 32; . The PPARs: from orphan receptors to drug discovery. J. Med. Chem. 43, 527-550]. By contrast, specific agonists of PPAR-delta/beta (GW501516) or PPAR-gamma (ciglitazone) have no such effect. In obese Zucker rats, which lack functional leptin receptors, OEA reduces food intake and lowers body-weight gain along with plasma lipid levels. Similar effects are seen in diet-induced obese rats and mice. In the present study, we report that subchronic OEA treatment (5mgkg(-1), intraperitoneally, i.p., once daily for two weeks) in Zucker rats initiates transcription of PPAR-alpha and other PPAR-alpha target genes, including fatty-acid translocase (FAT/CD36), liver fatty-acid binding protein (L-FABP), and uncoupling protein-2 (UCP-2). Moreover, OEA decreases neutral lipid content in hepatocytes, as assessed by Oil red O staining, as well as serum cholesterol and triglyceride levels. The results suggest that OEA regulates lipid metabolism and that this effect may contribute to its anti-obesity properties.

Topics: Animals; Body Weight; Butyrates; CD36 Antigens; Cholesterol; Coenzyme A Ligases; Eating; Endocannabinoids; Fatty Acid-Binding Proteins; Hepatocytes; Hyperlipidemias; Ion Channels; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitochondrial Proteins; Obesity; Oleic Acids; Phenylurea Compounds; PPAR alpha; Pyrimidines; Rats; Rats, Inbred WF; Rats, Zucker; RNA, Messenger; Thiazoles; Thiazolidinediones; Triglycerides; Uncoupling Protein 2

Amides of fatty acids with ethanolamine (FAE) are biologically active lipids that participate in a variety of biological functions, including the regulation of feeding. The polyunsaturated FAE anandamide (arachidonoylethanolamide) increases food intake by activating G protein-coupled cannabinoid receptors. On the other hand, the monounsaturated FAE oleoylethanolamide (OEA) reduces feeding and body weight gain by activating the nuclear receptor PPAR-alpha (peroxisome proliferator-activated receptor alpha). In the present report, we examined whether OEA can also influence energy utilization. OEA (1-20 microm) stimulated glycerol and fatty acid release from freshly dissociated rat adipocytes in a concentration-dependent and structurally selective manner. Under the same conditions, OEA had no effect on glucose uptake or oxidation. OEA enhanced fatty acid oxidation in skeletal muscle strips, dissociated hepatocytes, and primary cardiomyocyte cultures. Administration of OEA in vivo (5 mg kg(-1), intraperitoneally) produced lipolysis in both rats and wild-type mice, but not in mice in which PPAR-alpha had been deleted by homologous recombination (PPAR-alpha(-/-)). Likewise, OEA was unable to enhance lipolysis in adipocytes or stimulate fatty acid oxidation in skeletal muscle strips isolated from PPAR-alpha mice. The synthetic PPAR-alpha agonist Wy-14643 produced similar effects, which also were dependent on the presence of PPAR-alpha. Subchronic treatment with OEA reduced body weight gain and triacylglycerol content in liver and adipose tissue of diet-induced obese rats and wild-type mice, but not in obese PPAR-alpha(-/-) mice. The results suggest that OEA stimulates fat utilization through activation of PPAR-alpha and that this effect may contribute to its anti-obesity actions.

Topics: Adipose Tissue; Animals; Body Weight; Cell Nucleus; Cells, Cultured; Dose-Response Relationship, Drug; Endocannabinoids; Fatty Acids; Glucose; Glycerol; Hepatocytes; Ligands; Lipid Metabolism; Lipolysis; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Oleic Acids; Oxygen; Polymerase Chain Reaction; Pyrimidines; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Time Factors; Transcription Factors