title: The ketone body β-hydroxybutyric acid influences agouti-related peptide expression via AMP-activated protein kinase in hypothalamic GT1-7 cells.
abstract: β-Hydroxybutyric acid (BHBA) acts in the brain to influence feeding behaviour, but the underlying molecular mechanisms are unclear. GT1-7 hypothalamic cells expressing orexigenic agouti-related peptide (AGRP) were used to study the AMP-activated protein kinase (AMPK) pathway known to integrate dietary and hormonal signals for food intake regulation. In a 25 mM glucose culture medium, BHBA increased intracellular calcium concentrations and the expression of monocarboxylate transporter 1 (MCT1 (SLC16A1)). Phosphorylation of AMPK-α (PRKAA1 and PRKAA2) at Thr(172) was diminished after 2 h but increased after 4 h. Its downstream target, the mammalian target of rapamycin, was increasingly phosphorylated on Ser(2448) after 2 h but not changed after 4 h of BHBA treatment. After 4 h, BHBA treatment also increased Agrp mRNA expression. This increase was prevented by preincubation with the AMPK inhibitor Compound C. The inhibition of MCT1 activity by p-hydroxymercuribenzoate suppressed BHBA-stimulated AMPK phosphorylation but did not prevent BHBA-induced Agrp mRNA expression. This finding demonstrates that BHBA triggers the AMPK pathway resulting in orexigenic signalling under 25 mM glucose culture conditions. Under conditions of 5.5 mM glucose, however, BHBA marginally increased intracellular calcium but significantly decreased AMPK phosphorylation and Agrp mRNA expression, demonstrating that under physiological conditions BHBA reduces central orexigenic signalling.
authors.affiliation: Research Unit Nutritional Physiology Oskar Kellner Research Unit Reproductive Biology, Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Laeger
authors.forename: Ralf
authors.initials: R
authors.lastname: Pöhland
authors.forename: Cornelia C
authors.initials: CC
authors.lastname: Metges
authors.forename: Björn
authors.initials: B
authors.lastname: Kuhla
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000494:pharmacology*; D055372:AMP-Activated Protein Kinases / Q000502:physiology*; D054366:Agouti Signaling Protein / Q000096:biosynthesis*; D000818:Animals; D002478:Cells, Cultured; D005247:Feeding Behavior / Q000187:drug effects; D005947:Glucose / Q000008:administration & dosage; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D027501:Monocarboxylic Acid Transporters / Q000502:physiology; D027981:Symporters / Q000502:physiology; D058570:TOR Serine-Threonine Kinases / Q000502:physiology; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D020155:3-Hydroxybutyric Acid; D055372:AMP-Activated Protein Kinases; D054366:Agouti Signaling Protein; D005947:Glucose; D027501:Monocarboxylic Acid Transporters; D027981:Symporters; D058570:TOR Serine-Threonine Kinases; D000099233:Monocarboxylate Transport Protein 1; C515183:a protein, mouse; C546843:mTOR protein, mouse