title: Adiponectin stimulates glucose uptake in rabbit blastocysts.
abstract: Since the discovery of adipokines, the adipose tissue is no longer considered to be an inactive fat storage. It secretes a variety of bioactive molecules, which regulate body metabolism and energy homeostasis. One of these molecules is the adipokine adiponectin. In different tissues, adiponectin triggers metabolic effects through the adenosine monophosphate-activated protein kinase (PRKA), which is a master regulator in glucose and lipid metabolism. Recent studies point to a role for adiponectin in reproduction. Adiponectin and its receptors are present in female reproductive tract during pregnancy, and the preimplantation embryo is fully equipped with adiponectin. Here, we show that both receptor isoforms, ADIPOR1 and ADIPOR2, are expressed in 6-day-old rabbit blastocysts. To investigate the signaling pathway of adiponectin in preimplantation embryos, rabbit blastocysts were cultured in vitro and stimulated with adiponectin. Supplementation of adiponectin (1 μg/ml) enhanced PRKA alpha 1/2 (PRKAA1/2) phosphorylation and decreased expression of phosphoenolpyruvate carboxykinase 2 (PCK2), a key regulator of gluconeogenesis. Inhibition of PRKAA1/2 by Compound C (10 μM) restored PCK2 transcription. Adiponectin enhanced embryonic glucose uptake and led to a translocation of solute carrier family 2 (facilitated glucose transporter), member 4 (SLC2A4), previously known as GLUT4. We conclude that adiponectin influences the glucose metabolism of rabbit blastocysts via the phosphorylation of PRKAA1/2, which in turn results in a decrease of gluconeogenesis and an increase in glycolysis. The regulatory influence of adiponectin on glucose metabolism of blastocysts may be of specific interest in pathophysiological situations, such as obesity during pregnancy.
authors.affiliation: Department of Anatomy and Cell Biology, Martin Luther University Faculty of Medicine, Halle (Saale), Germany.
authors.forename: Suenje
authors.initials: S
authors.lastname: Fischer
authors.forename: Anne Navarrete
authors.initials: AN
authors.lastname: Santos
authors.forename: René
authors.initials: R
authors.lastname: Thieme
authors.forename: Nicole
authors.initials: N
authors.lastname: Ramin
authors.forename: Bernd
authors.initials: B
authors.lastname: Fischer
mesh_terms: D019325:3-O-Methylglucose / Q000378:metabolism; D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D052242:Adiponectin / Q000096:biosynthesis / Q000302:isolation & purification / Q000502:physiology; D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D046149:Embryo Culture Techniques; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006801:Humans; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011247:Pregnancy; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D054419:Receptors, Adiponectin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D015398:Signal Transduction
chemical_list: C499918:ADIPOQ protein, human; D052242:Adiponectin; D051275:Glucose Transporter Type 4; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D054419:Receptors, Adiponectin; D011994:Recombinant Proteins; D019325:3-O-Methylglucose; D055372:AMP-Activated Protein Kinases; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D005947:Glucose