Adiponectin stimulates lipid metabolism via AMPK in rabbit blastocysts

Abstract

STUDY QUESTIONHow does a maternal diabetic hyperadiponectineamia affect signal transduction and lipid metabolism in rabbit preimplantation blastocysts?SUMMARY ANSWERIn a diabetic pregnancy increased levels of adiponectin led to a switch in embryonic metabolism towards a fatty acid-dependent energy metabolism, mainly affecting genes that are responsible for fatty acid uptake and turnover.WHAT IS KNOWN ALREADYAlthough studies in cell culture experiments have shown that adiponectin is able to regulate lipid metabolism via 5′-AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor α (PPARα), data on the effects of adiponectin on embryonic lipid metabolism are not available. In a diabetic pregnancy in rabbits, maternal adiponectin levels are elevated fourfold and are accompanied by an increase in intracellular lipid droplets in blastocysts, implying consequences for the embryonic hormonal and metabolic environment.STUDY DESIGN, SIZE, DURATIONRabbit blastocysts were cultured in vitro with adiponectin (1 μg/ml) and with the specific AMPK-inhibitor Compound C for 15 min, 1 h and 4 h (N ≥ 3 independent experiments: for RNA analysis, n ≥ 4 blastocysts per treatment group; for protein analysis three blastocysts pooled per sample and three samples used per experiment). Adiponectin signalling was verified in blastocysts grown in vivo from diabetic rabbits with a hyperadiponectinaemia (N ≥ 3 independent experiments, n ≥ 4 samples per treatment group, eight blastocysts pooled per sample).PARTICIPANTS/MATERIALS, SETTING, METHODSIn these blastocysts, expression of molecules involved in adiponectin signalling [adaptor protein 1 (APPL1), AMPK, acetyl-CoA carboxylase (ACC), p38 mitogen-activated protein kinases (p38 MAPK)], lipid metabolism [PPARα, cluster of differentiation 36 (CD36), fatty acid transport protein 4 (FATP4), fatty acid binding protein (FABP4), carnitine palmityl transferase 1 (CPT1), hormone-senstive lipase (HSL), lipoprotein lipase (LPL)] and members of the insulin/insulin-like growth factor (IGF)-system [IGF1, IGF2, insulin receptor (InsR), IGF1 receptor (IGF1R)] were analyzed by quantitative RT-PCR and western blot. Analyses were performed in both models, i.e. adiponectin stimulated blastocysts (in vitro) and in blastocysts grown in vivo under increased adiponectin levels caused by a maternal diabetes mellitus.MAIN RESULTS AND THE ROLE OF CHANCEIn both in vitro and in vivo models adiponectin increased AMPK and ACC phosphorylation, followed by an activation of the transcription factor PPARα, and CPT1, the key enzyme of β-oxidation (all P < 0.05 versus control). Moreover, mRNA levels of the fatty acid transporters CD36, FATP4 and FABP4, and HSL were upregulated by adiponectin/AMPK signalling (all P < 0.05 versus control). Under diabetic developmental conditions the amount of p38 MAPK was upregulated (P < 0.01 versus non-diabetic), which was not observed in blastocysts cultured in vitro with adiponectin, indicating that the elevated p38 MAPK was not related to adiponectin. However,...

Metabolic Profiling in Blastocoel Fluid and Blood Plasma of Diabetic Rabbits

“…In BF, short chain carnitine-bound fatty acids, like acetylcarnitine, 3-hydroxybutyrylcanitine and hexanoylcarnitine, were also increased, indicating impaired embryonic beta-oxidation as well. We have recently shown that CPT1 is increased in blastocysts from diabetic rabbits [43], indicating increased fatty acid oxidation in blastocysts from diabetic rabbits. This result is in line with the observed elevated BHBA levels in maternal plasma and BF due to diabetes mellitus.…”

“…This key phospholipid is an important activator of the p38 MAPK pathway under conditions of cell stress and lipotoxicity [51]. In blastocysts from diabetic rabbits, the p38 MAPK pathway is activated [43], indicating that high 1-stearoyl-2-arachidonoyl-GPC levels activate p38 MAPK pathway in embryonic cells.…”

“…Experimental insulin-dependent diabetes (DT1) was induced in mature 18 to 20 week-old female non-pregnant rabbits (outbred ZIKA-hybrid New Zealand White) by alloxan treatment (Sigma-Aldrich, Taufkirchen, Germany), as described by [18]. Rabbits were maintained under diabetic conditions (blood glucose levels 15-25 mmol/l, daily insulin supplementation) as described by [43] for at least 10 days before mating. All animal experiments were performed in accordance with the principles of laboratory animal care and the experimental protocol was approved by the local ethics committee (Landesverwaltungsamt Dessau; reference number: 42502-2-812, 31 January 2011).…”

Multifaceted Physiological Roles of Adiponectin in Inflammation and Diseases

“…Studies have reported that HMW adiponectin is involved in insulin sensitivity, glucose uptake, and lipid metabolism. Investigative research has reported the involvement of different adiponectin isoforms in the pathogenesis of various diseases [5]. It has also been shown that these isoforms act as acute-phase reactants that influence inflammatory mechanisms in both acute and chronic diseases.…”

Dietary choline supplementation attenuated high-fat diet-induced inflammation through regulation of lipid metabolism and suppression of NFκB activation in juvenile black seabream (Acanthopagrus schlegelii)

“…Previous studies demonstrated that fat deposition could be decreased by downregulating the expression of lipogenesis pathway genes such as sterol regulatory element-binding protein-1(srebp-1), acetyl-CoA carboxylase α (accα) and fatty acid synthase ( fas), and/ or up-regulation of lipolysis pathway genes such as PPARα ( pparα), hormone-sensitive lipase (hsl) and carnitine palmitoyltransferase 1A (cpt1a) (16)(17)(18)(19) . In addition, adiponectin, a hormone involved in the regulation of glucose metabolism and fatty acid breakdown in mammals, could lower intracellular lipid content (20) . Therefore, dietary supplements that can regulate lipid metabolism or adiponectin and, consequently, reduce excess lipid deposition, alleviate hepatic steatosis and attenuate inflammation response would be highly beneficial.…”