Activation of the omega-3 fatty acid receptor GPR120 mediates anti-inflammatory actions in immortalized hypothalamic neurons. 2014

Leigh Wellhauser, and Denise D Belsham

BACKGROUND Overnutrition and the ensuing hypothalamic inflammation is a major perpetuating factor in the development of metabolic diseases, such as obesity and diabetes. Inflamed neurons of the CNS fail to properly regulate energy homeostasis leading to pathogenic changes in glucose handling, feeding, and body weight. Hypothalamic neurons are particularly sensitive to pro-inflammatory signals derived locally and peripherally, and it is these neurons that become inflamed first upon high fat feeding. Given the prevalence of metabolic disease, efforts are underway to identify therapeutic targets for this inflammatory state. At least in the periphery, omega-3 fatty acids and their receptor, G-protein coupled receptor 120 (GPR120), have emerged as putative targets. The role for GPR120 in the hypothalamus or CNS in general is poorly understood. METHODS Here we introduce a novel, immortalized cell model derived from the rat hypothalamus, rHypoE-7, to study GPR120 activation at the level of the individual neuron. Gene expression levels of pro-inflammatory cytokines were studied by quantitative reverse transcriptase-PCR (qRT-PCR) upon exposure to tumor necrosis factor α (TNFα) treatment in the presence or absence of the polyunsaturated omega-3 fatty acid docosahexaenoic acid (DHA). Signal transduction pathway involvement was also studied using phospho-specific antibodies to key proteins by western blot analysis. RESULTS Importantly, rHypoE-7 cells exhibit a transcriptional and translational inflammatory response upon exposure to TNFα and express abundant levels of GPR120, which is functionally responsive to DHA. DHA pretreatment prevents the inflammatory state and this effect was inhibited by the reduction of endogenous GPR120 levels. GPR120 activates both AKT (protein kinase b) and ERK (extracellular signal-regulated kinase); however, the anti-inflammatory action of this omega-3 fatty acid (FA) receptor is AKT- and ERK-independent and likely involves the GPR120-transforming growth factor-β-activated kinase 1 binding protein (TAB1) interaction as identified in the periphery. CONCLUSIONS Taken together, GPR120 is functionally active in the hypothalamic neuronal line, rHypoE-7, wherein it mediates the anti-inflammatory actions of DHA to reduce the inflammatory response to TNFα.

UI MeSH Term Description Entries
D007031 Hypothalamus Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE. Lamina Terminalis,Preoptico-Hypothalamic Area,Area, Preoptico-Hypothalamic,Areas, Preoptico-Hypothalamic,Preoptico Hypothalamic Area,Preoptico-Hypothalamic Areas
D008744 Methylamines Derivatives of methylamine (the structural formula CH3NH2).
D009474 Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM. Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D011422 Propionates Derivatives of propionic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxyethane structure. Propanoate,Propanoic Acid,Propionate,Propanoates,Propanoic Acid Derivatives,Propanoic Acids,Propionic Acid Derivatives,Propionic Acids,Acid, Propanoic,Acids, Propanoic,Acids, Propionic,Derivatives, Propanoic Acid,Derivatives, Propionic Acid
D011725 Pyridines Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.
D002461 Cell Line, Transformed Eukaryotic cell line obtained in a quiescent or stationary phase which undergoes conversion to a state of unregulated growth in culture, resembling an in vitro tumor. It occurs spontaneously or through interaction with viruses, oncogenes, radiation, or drugs/chemicals. Transformed Cell Line,Cell Lines, Transformed,Transformed Cell Lines
D004281 Docosahexaenoic Acids C22-unsaturated fatty acids found predominantly in FISH OILS. Docosahexaenoate,Docosahexaenoic Acid,Docosahexenoic Acids,Docosahexaenoic Acid (All-Z Isomer),Docosahexaenoic Acid Dimer (All-Z Isomer),Docosahexaenoic Acid, 3,6,9,12,15,18-Isomer,Docosahexaenoic Acid, 4,7,10,13,16,19-(All-Z-Isomer),Docosahexaenoic Acid, 4,7,10,13,16,19-(All-Z-Isomer), Cerium Salt,Docosahexaenoic Acid, 4,7,10,13,16,19-(All-Z-Isomer), Cesium Salt,Docosahexaenoic Acid, 4,7,10,13,16,19-(All-Z-Isomer), Potassium Salt,Docosahexaenoic Acid, 4,7,10,13,16,19-(Z,Z,Z,Z,Z,E-Isomer),Docosahexaenoic Acid, 4,7,10,13,16,19-Isomer,Docosahexaenoic Acid, 4,7,10,13,16,19-Isomer, Sodium Salt,Docosahexaenoic Acid, Sodium Salt,Acid, Docosahexaenoic,Acids, Docosahexaenoic,Acids, Docosahexenoic
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004791 Enzyme Inhibitors Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction. Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D006575 Heterocyclic Compounds, 3-Ring A class of heterocyclic compounds that include a three-ring fused structure. Both aromatic or non-aromatic ring structures are included in this category. Fused Heterocyclic Compounds, Three-Ring,Heterocyclic Cpds, 3 Ring,Three Ring Heterocyclic Compounds,3-Ring Heterocyclic Compounds,Fused Heterocyclic Compounds, Three Ring,Heterocyclic Compounds, 3 Ring

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