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The xenoestrogen bisphenol A (BPA) is a widespread plasticizer detectable within several ecosystems. BPA is considered a metabolic disruptor, affecting different organs; however, little is known about its mechanism of action in the liver, in which it triggers triglyceride accumulation. Adult zebrafish (Danio rerio) exposed to BPA developed hepatosteatosis, which was associated with an increase in the liver levels of the obesogenic endocannabinoids 2-arachidonoylglycerol and anandamide and a concomitant decrease in palmitoylethanolamide. These changes were associated with variations in the expression of key endocannabinoid catabolic and metabolic enzymes and an increase in the expression of the endocannabinoid receptor cnr1. Acute and chronic in vitro treatments with nano- and micromolar BPA doses showed increased anandamide levels in line with decreased activity of fatty acid amide hydrolase, the main anandamide hydrolytic enzyme, and induced triglyceride accumulation in HHL-5 cells in a CB1-dependent manner. We conclude that BPA is able to produce hepatosteatosis in zebrafish and human hepatocytes by up-regulating the endocannabinoid system.

International audience; Evidence suggests that alterations of glucose and lipid homeostasis induced by obesity are associated with the elevation of endocannabinoid tone. The biosynthesis of the two main endocannabinoids, N-arachidonoylethanolamine and 2-arachidonoyl-glycerol, which derive from arachidonic acid, is influenced by dietary fatty acids (FAs). We investigated whether exposure to n-3 FA at a young age may decrease tissue endocannabinoid levels and prevent metabolic disorders induced by a later high-fat diet (HFD) challenge. Three-week-old mice received a 5% lipid diet containing lard, lard plus safflower oil, or lard plus linseed oil for 10 weeks. Then, mice were challenged with a 30% lard diet for 10 additional weeks. A low n-6/n-3 FA ratio in the early diet induces a marked decrease in liver endocannabinoid levels. A similar reduction was observed in transgenic Fat-1 mice, which exhibit high tissue levels of n-3 FA compared with wild-type mice. Hepatic expression of key enzymes involved in carbohydrate and lipid metabolism was concomitantly changed. Interestingly, some gene modifications persisted after HFD challenge and were associated with improved glycemic control. These findings indicate that early dietary interventions based on n-3 FA may represent an alternative strategy to drugs for reducing endocannabinoid tone and improving metabolic parameters in the metabolic syndrome.

Excessive abdominal obesity along with other risk factors results in the metabolic syndrome, which can lead to heart disease, Type-2 diabetes, and death. The endocannabinoid system (ECS) is composed of neutral lipids which signal through the G-protein coupled cannabinoid receptors CB1 and CB2. In abdominal obesity, the ECS is generally up-regulated in central and peripheral tissues and its blockade results in positive metabolic changes. Rimonabant (SR141716) was the first selective CB1 inverse agonist/antagonist marketed for the treatment of obesity; however, psychiatric side effects, which may result from its actions in the brain or its inverse agonism, resulted in its removal from the market. Recently, key metabolic-modulatory roles for the ECS within peripheral tissues have come to light. Thus there has been significant effort put forth by several laboratories to develop either neutral or peripherally restricted CB1 antagonists.In this review we shall provide an overview of the roles the ECS plays outside the brain in regulating metabolism, and highlight the latest advances in the development of neutral and/or peripherally restricted CB1 antagonists, and other state of the art strategies that minimize endocannabinoid overactivity.The CB1 receptor is potentially a clinically relevant target for the design of therapies against metabolic syndrome, deserving the development and clinical testing of CB1-neutral antagonists which can pass the blood - brain barrier or of peripherally restricted inverse agonists/neutral antagonists. Furthermore, reducing endocannabinoid biosynthesis could represent an alternative strategy to counteract peripheral endocannabinoid overactivity through dietary n-3 polyunsaturated fatty acids or the development of diacylglycerol lipase inhibitors.

The endocannabinoid system (ECS) is composed of lipid signalling ligands, their G-protein coupled receptors and the enzymes involved in ligand generation and metabolism. Increasingly, the ECS is emerging as a critical agent of energy metabolism regulation through its ability to modulate caloric intake centrally as well as nutrient transport, cellular metabolism and energy storage peripherally. Visceral obesity has been associated with an upregulation of ECS activity in several systems and inhibition of the ECS, either pharmacologically or genetically, results in decreased energy intake and increased metabolic output. This review aims to summarize the recent advances that have been made regarding our understanding of the role the ECS plays in crucial peripheral systems pertaining to energy homeostasis: adipose tissues, the liver and skeletal muscle.

SummaryFoxh1, a Smad DNA-binding partner, mediates TGFβ-dependent gene expression during early development. Few Foxh1 targets are known. Here, we describe a genome-wide approach that we developed that couples systematic mapping of a functional Smad/Foxh1 enhancer (SFE) to Site Search, a program used to search annotated genomes for composite response elements. Ranking of SFEs that are positionally conserved across species yielded a set of genes enriched in Foxh1 targets. Analysis of top candidates, such as Hesx1, Lgr4, Lmo1, Fgf8, and members of the Aldh1a subfamily, revealed that Foxh1 initiates a transcriptional regulatory network within the developing anterior neuroectoderm. The Aldh1a family is required for retinoic acid (RA) synthesis, and, in Foxh1 mutants, expression of Aldh1a1, -2, and -3 and activation of a RA-responsive transgenic reporter is abolished in anterior structures. Integrated mapping of a developmental transcription factor network thus reveals a key role for Foxh1 in patterning and initiating RA signaling in the forebrain.

The adipocyte-derived, anorectic hormone leptin was recently shown to owe part of its regulatory effects on appetite-regulating hypothalamic neuropeptides to the elevation of reactive oxygen species (ROS) levels in arcuate nucleus (ARC) neurons. Leptin is also known to exert a negative regulation on hypothalamic endocannabinoid levels and hence on cannabinoid CB1 receptor activity. Here we investigated the possibility of a negative regulation by CB1 receptors of leptin-mediated ROS formation in the ARC. Through pharmacological and molecular biology experiments we report data showing that leptin-induced ROS accumulation is 1) blunted by arachidonyl-2′-chloroethylamide (ACEA) in a CB1-dependent manner in both the mouse hypothalamic cell line mHypoE-N41 and ARC neuron primary cultures, 2) likewise blocked by a peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist, troglitazone, in a manner inhibited by T0070907, a PPAR-γ antagonist that also inhibited the ACEA effect on leptin, 3) blunted under conditions of increased endocannabinoid tone due to either pharmacological or genetic inhibition of endocannabinoid degradation in mHypoE-N41 and primary ARC neuronal cultures from MAGL−/− mice, respectively, and 4) associated with reduction of both PPAR-γ and catalase activity, which are reversed by both ACEA and troglitazone. We conclude that CB1 activation reverses leptin-induced ROS formation and hence possibly some of the ROS-mediated effects of the hormone by preventing PPAR-γ inhibition by leptin, with subsequent increase of catalase activity. This mechanism might underlie in part CB1 orexigenic actions under physiopathological conditions accompanied by elevated hypothalamic endocannabinoid levels. Background: In hypothalamic neurons, leptin induces ROS production via PPAR-γ inhibition. Results: CB1 agonism prevents leptin-induced ROS accumulation by reversing PPAR-γ and catalase inhibition. Inhibition of endocannabinoid inactivation also counteracts leptin effects. Conclusion: CB1 inhibits effects of leptin that underlie part of its anorexic actions. Significance: During conditions of increased endocannabinoid tone CB1 might reduce leptin activity in the hypothalamus.

Background & Aims Obesity and associated metabolic syndrome have quickly become a pandemic and a major detriment to global human health. The presence of non-alcoholic fatty liver disease (NAFLD; hepatosteatosis) in obesity has been linked to the worsening of the metabolic syndrome, including the development of insulin resistance and cardiovascular disease. Currently, there are few options to treat NAFLD, including life style changes and insulin sensitizers. Recent evidence suggests that the cannabinoids Δ 9 -tetrahydrocannabivarin (THCV) and cannabidiol (CBD) improve insulin sensitivity; we aimed at studying their effects on lipid levels. Methods The effects of THCV and CBD on lipid levels were examined in a variety of in vitro and in vivo systems, with special emphasis on models of hepatosteatosis. Transcriptional, post-translational and metabolomic changes were assayed. Results THCV and CBD directly reduce accumulated lipid levels in vitro in a hepatosteatosis model and adipocytes. Nuclear magnetic resonance- (NMR) based metabolomics confirmed these results and further identified specific metabolic changes in THCV and CBD-treated hepatocytes. Treatment also induced post-translational changes in a variety of proteins such as CREB, PRAS40, AMPKa2 and several STATs indicating increased lipid metabolism and, possibly, mitochondrial activity. These results are supported by in vivo data from zebrafish and obese mice indicating that these cannabinoids are able to increase yolk lipid mobilization and inhibit the development of hepatosteatosis respectively. Conclusions Our results suggest that THCV and CBD might be used as new therapeutic agents for the pharmacological treatment of obesity- and metabolic syndrome-related NAFLD/hepatosteatosis.

The anterior heart field (AHF) mediates formation of the outflow tract (OFT) and right ventricle (RV) during looping morphogenesis of the heart. Foxh1 is a forkhead DNA binding transcription factor in the TGFbeta-Smad pathway. Here we demonstrate that Foxh1-/- mutant mouse embryos form a primitive heart tube, but fail to form OFT and RV and display loss of outer curvature markers of the future working myocardium, similar to the phenotype of Mef2c-/- mutant hearts. Further, we show that Mef2c is a direct target of Foxh1, which physically and functionally interacts with Nkx2-5 to mediate strong Smad-dependent activation of a TGFbeta response element in the Mef2c gene. This element directs transgene expression to the presumptive AHF, as well as the RV and OFT, a pattern that closely parallels endogenous Mef2c expression in the heart. Thus, Foxh1 and Nkx2-5 functionally interact and are essential for development of the AHF and its derivatives, the RV and OFT, in response to TGFbeta-like signals.

Little is known of the involvement of endocannabinoids and cannabinoid receptors in skeletal muscle cell differentiation. We report that, due to changes in the expression of genes involved in its metabolism, the levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) are decreased both during myotube formation in vitro from murine C2C12 myoblasts and during mouse muscle growth in vivo. The endocannabinoid, as well as the CB1 agonist arachidonoyl-2-chloroethylamide, prevent myotube formation in a manner antagonized by CB1 knockdown and by CB1 antagonists, which, per se, instead stimulate differentiation. Importantly, 2-AG also inhibits differentiation of primary human satellite cells. Muscle fascicles from CB1 knockout embryos contain more muscle fibers, and postnatal mice show muscle fibers of an increased diameter relative to wild-type littermates. Inhibition of Kv7.4 channel activity, which plays a permissive role in myogenesis and depends on phosphatidylinositol 4,5-bisphosphate (PIP2), underlies the effects of 2-AG. We find that CB1 stimulation reduces both total and Kv7.4-bound PIP2 levels in C2C12 cells and inhibits Kv7.4 currents in transfected CHO cells. We suggest that 2-AG is an endogenous repressor of myoblast differentiation via CB1-mediated inhibition of Kv7.4 channels.

The Smad family of proteins are critical components of the TGFβ superfamily signalling pathway. Ligand addition induces phosphorylation of specific receptor-regulated Smads, which then form heteromeric complexes with the common mediator Smad, Smad4. This complex then translocates from the cytoplasm into the nucleus. Once there, the R-Smad/Smad4 complex interacts with a variety of DNA binding proteins and is thereby targetted to a diverse array of gene promoters. The Smad-containing DNA binding complex can then positively or negatively regulate gene expression through the recruitment of co-activators and co-repressors. Xenopus FAST (now known as FoxH1) was the first Smad DNA binding partner identified and the FoxH1 family now includes related proteins from mouse, human and Zebrafish. In all organisms examined, FoxH1 is expressed primarily during the earliest stages of development and thus FoxH1 is thought to play a critical role in mediating TGFβ superfamily signals during these early developmental stages. Other Smad partners range from those that are ubiquitously expressed to others that are present only in specific cell types or developmental stages. Thus, it is the interaction of Smads with a wide range of specific transcriptional partners that is important for the generation of diverse biological responses to TGFβ superfamily members.

Endocannabinoids and cannabinoid CB1 receptors are known to play a generalized role in energy homeostasis. However, clinical trials with the first generation of CB1 blockers, now discontinued due to psychiatric side effects, were originally designed to reduce food intake and body weight rather than the metabolic risk factors associated with obesity. In this review, we discuss how, in addition to promoting energy intake, endocannabinoids control lipid and glucose metabolism in several peripheral organs, particularly the liver and adipose tissue. Direct actions in skeletal muscle and pancreas are also emerging. This knowledge may help in the design of future therapies for the metabolic syndrome. © 2013 Elsevier Inc.

Lipid mediators variedly affect adipocyte differentiation. Anandamide stimulates adipogenesis via CB1 receptors and peroxisome proliferator-activated receptor γ. Anandamide may be converted by PTGS2 (COX2) and prostaglandin F synthases, such as prostamide/prostaglandin F synthase, to prostaglandin F2α ethanolamide (PGF2αEA), of which bimatoprost is a potent synthetic analog. PGF2αEA/bimatoprost act via prostaglandin F2αFP receptor/FP alt4 splicing variant heterodimers. We investigated whether prostamide signaling occurs in preadipocytes and controls adipogenesis. Exposure of mouse 3T3-L1 or human preadipocytes to PGF2αEA/bimatoprost during early differentiation inhibits adipogenesis. PGF2αEA is produced from anandamide in preadipocytes and much less so in differentiating adipocytes, which express much less PTGS2, FP, and its alt4 splicing variant. Selective antagonism of PGF2αEA receptors counteracts prostamide effects on adipogenesis, as does inhibition of ERK1/2 phosphorylation. Selective inhibition of PGF2αEA versus prostaglandin F2α biosynthesis accelerates adipogenesis. PGF2αEA levels are reduced in the white adipose tissue of high fat diet-fed mice where there is a high requirement for new adipocytes. Prostamides also inhibit zebrafish larval adipogenesis in vivo. We propose that prostamide signaling in preadipocytes is a novel anandamide-derived antiadipogenic mechanism.

Publisher Summary Transforming Growth Factor β (TGFβ) superfamily members are expressed and function ubiquitously throughout early development and the lifetime of higher animals from worms to humans. TGFβ ligands transduce their signals into cells via transmembrane serine/threonine kinase receptors. In general, the formation of a heteromeric complex of ligand and receptors induces the phosphorylation of the receptor-regulated Smads (R-Smads) within the cytoplasm. This phosphorylation results in R-Smad activation, freeing the R-Smad from the receptors and allowing for the formation of a heteromeric complex with the common Smad, Smad4. These active R-Smad/Smad4 complexes accumulate in the nucleus, and function in conjunction with a host of nuclear co-factors to regulate the transcription of target genes. TGFβ family members transduce signals across the plasma membrane via the formation of an active heteromeric complex of type II and type I receptors. Smads are the best-characterized intracellular mediators of TGFβ signals. They are a group of eight structurally related proteins in humans with homologs identified in organisms as diverse as worms to humans. The MH1 domain is responsible for nuclear import, DNA binding, and interactions with transcription factors, while the MH2 mediates interactions with receptors, Smad oligomerization, and interactions with transcription factors, co-activators, and co-repressors. While the inhibitory Smads (I-Smads), Smad6 and Smad7, share structural similarities with the R-Smads, they function to negatively regulate TGFβ signaling. I-Smads inhibit TGFβ signaling by targeting different points within the signaling cascade.

13 páginas, 8 figuras -- PAGS nros. 456-468, The endothelial nitric oxide synthase (eNOS) is a critical regulator of cardiovascular homeostasis, whose dysregulation leads to different vascular pathologies. Endoglin is a component of the transforming growth factor beta (TGF-β) receptor complex present in endothelial cells that is involved in angiogenesis, cardiovascular development, and vascular homeostasis. Haploinsufficient expression of endoglin has been shown to downregulate endothelium-derived nitric oxide in endoglin+/− (Eng+/−) mice and cultured endothelial cells. Here, we find that TGF-β1 leads to an increased vasodilatation in Eng+/+ mice that is severely impaired in Eng+/− mice, suggesting the involvement of endoglin in the TGF-β regulated vascular homeostasis. The endoglin-dependent induction of eNOS occurs at the transcriptional level and is mediated by the type I TGF-β receptor ALK5 and its downstream substrate Smad2. In addition, Smad2-specific signaling is upregulated in endoglin-induced endothelial cells, whereas it is downregulated upon endoglin gene suppression with small interference RNA (siRNA). The endoglin-dependent upregulation of Smad2 was confirmed using eNOS and pARE promoters, whose activities are known to be Smad2 dependent, as well as with the interference of Smad2 with siRNA, Smurf2, or a dominant negative form of Smad2. Furthermore, increased expression of endoglin in endoglin-inducible endothelial cells or in transfectants resulted in increased levels of Smad2 protein without affecting the levels of Smad2 mRNA. The increased levels of Smad2 appear to be due to a decreased ubiquitination and proteasome-dependent degradation leading to stabilization of Smad2. These results suggest that endoglin enhances Smad2 protein levels potentiating TGF-β signaling, and leading to an increased eNOS expression in endothelial cells. J. Cell. Physiol. 210: 456–468, 2007. © 2006 Wiley-Liss, Inc., ALK, activin receptor-like kinase; Dox, doxycycline; eNOS, endothelial nitric oxide synthase; MEFs, murine embryonic fibroblasts; Pp, perfusion pressure; siRNA, small interference RNA; TGF-β, transforming growth factor-β; TβRI, TGF-β type I receptor; TβRII, TGF-β type II receptor; HHT, hereditary hemorrhagic telangiectasia. The endothelial nitric oxide synthase (eNOS or NOS3) is a critical regulator of cardiovascular homeostasis, vascular remodeling, and angiogenesis, and whose dysregulation leads to different types of vascular pathology (Kawashima and Yokoyama, 2004; Sessa, 2004; Tai et al., 2004). eNOS-derived NO is an endogenous vasodilatory molecule that regulates the tone of blood vessels and maintains an anti-thrombotic, anti-proliferative, and anti-apoptotic environment in the vessel wall (Sessa, 2004). Elucidation of the mechanisms and factors determining the expression and activity of eNOS under different physiological and pathophysiological conditions has long been considered central in order to understand the alterations in vascular NO production (Tai et al., 2004). The expression of eNOS is regulated by extracellular stimuli such as shear stress, estrogens, hypoxia, or growth factors (Davis et al., 2001; Simoncini et al., 2002; Tai et al., 2004). Among these, TGF-β1 has been shown to increase bovine aortic endothelial cell (BAEC) and human umbilical vein endothelial cell (HUVEC) steady-state eNOS mRNA expression (Inoue et al., 1995). Interestingly, eNOS expression is modulated not only by transcriptional, but also by post-transcriptional mechanisms (Sessa, 2004; Tai et al., 2004). At the transcriptional level, the eNOS promoter lacks a TATA box, but exhibits proximal elements such as Sp1 and GATA motifs, which are common characteristics of constitutively expressed genes (Zhang et al., 1995; Tai et al., 2004). The 5′-flanking region also contains many putative sites for further transcriptional regulation of eNOS. However, only a few of these sites have been formally shown to regulate eNOS transcription, including PEA3 (Cieslik et al., 1998) and AP-1 binding sites (Navarro-Antolin et al., 2000). Also, a region of the eNOS promoter extending from −1269 and −935 that contains Smad binding sites and mediates TGF-β induction of eNOS transcription, has been identified (Saura et al.,2002), Endoglin (CD105), is a 180-kDa homodimeric membrane glycoprotein which is strongly expressed by human endothelial cells and is involved in angiogenesis, cardiovascular development, and vascular homeostasis (Gougos and Letarte, 1990; Duff et al., 2003; Lebrin et al., 2005). The gene encoding endoglin has been identified as the target for the dominant vascular disorder known as hereditary hemorrhagic telangiectasia type 1 (HHT1) (Guttmacher et al., 1995). HHT is a highly penetrant autosomal dominant vascular dysplasia associated with frequent epistaxis, gastrointestinal bleedings, telangiectases, and arteriovenous malformations in brain, lung, and liver (Shovlin and Letarte, 1999; Marchuk and Lux, 2001). The mechanistic role of endoglin in angiogenesis and vascular remodeling is not known, but it is likely related to the transforming growth factor-β (TGF-β) system, as endoglin is a functional component of the membrane TGF-β receptor complex (Lastres et al., 1996) and is a substrate for TGF-β receptor-mediated phosphorylation (Guerrero-Esteo et al., 2002; Koleva et al., 2006). Signaling induction by TGF-β and related members of this superfamily regulate a variety of human diseases including cancer, fibrosis, developmental disorders, or cardiovascular pathology (Blobe et al., 2000; Siegel and Massague, 2003; Waite and Eng, 2003; Lebrin et al., 2005). TGF-β signaling is initiated when ligand induces formation of heteromeric complexes of type I and type II serine/threonine kinase receptors (TβRI and TβRII, respectively), which in turn activate and induce translocation of the Smad family of proteins to the nucleus (Attisano and Wrana, 2002; Miyazawa et al., 2002; Shi and Massague, 2003; Feng and Derynck, 2005). The association of endoglin with TβRII and TβRI (ALK1 and ALK5) regulates Smad signaling and cellular responses to TGF-β (Lastres et al., 1996; Letamendia et al., 1998; Li et al., 2000; Guerrero-Esteo et al., 2002). Endoglin regulates signal transduction of TGF-β1 by potentiating ALK1/Smad1 pathway and repressing the ALK5/Smad3 (Lebrin et al., 2004; Blanco et al., 2005), whereas it enhances ALK5/Smad2 signaling (Guerrero-Esteo et al., 2002). Conversely, in endoglin-deficient mice it has been shown that TGF-β/ALK5 signaling from endothelial cells to adjacent mesothelial cells is defective, as evidenced by reduced phosphorylation of Smad2 (Carvalho et al., 2004)., Recently, it has been shown that endoglin regulates nitric oxide-dependent vasodilatation, as well as eNOS expression and activity (Jerkic et al., 2004; Toporsian et al., 2005). In addition, eNOS derived NO seems to play a major role in endoglin-dependent angiogenesis (Jerkic et al., 2006a) and COX-2 regulated expression (Jerkic et al., 2006b). The role of endoglin in the control of vascular tone was examined by measuring NO-dependent vasodilation in haploinsufficient mice (Eng+/−) and their Eng+/+ littermates (Jerkic et al., 2004). Urinary and plasma concentrations of nitrites were lower in Eng+/− than in Eng+/+ mice. The levels of eNOS in kidneys and femoral arteries were about half in Eng+/− than in Eng+/+ mice and were also reduced in primary cultures of aortic endothelial cells from Eng+/− compared with those from Eng+/+ mice. Furthermore, overexpression or suppression of endoglin in cultured cells induced a marked increase or decrease in the protein levels of eNOS, respectively (Jerkic et al., 2004). However, the mechanisms by which endoglin regulates eNOS expression are poorly understood. In the present work we show that endoglin enhances eNOS expression by increasing Smad2 protein levels and thereby enhancing TGF-β-dependent induction of eNOS in endothelial cells, This work was supported by Ministerio de Educacion y Ciencia, Spain; grant numbers: SAF2004-01390 to C.B. and BFU2004-00285/BFI to J.M.L.-N.; Fondo de Investigaciœn Sanitaria, Spain; grant number: PI020200 to C.B.; COBRE Program, National Center for Research Resources, NIH, USA; grant number: P20-RR15555 to C.P.H.V.; Fondo Nacional de Ciencia y Tecnologia, Chile; grant number: FONDECYT-1050476 to J.F.S.; HHT Foundation International, Inc.; grant number: 3 to C.B.; Canadian Institute of Health Research (CIHR) to L.A.

Objective: Endocannabinoids and neuropeptide Y (NPY) promote energy storage via central and peripheral mechanisms. In the hypothalamus, the two systems were suggested to interact. To investigate such interplay also in non-hypothalamic tissues, we evaluated endocannabinoid levels in obese OE-NPYDβH mice, which overexpress NPY in the noradrenergic neurons in the sympathetic nervous system and the brain. Methods: The levels of the endocannabinoids anandamide and 2-arachidonoylglycerol (2-AG) were measured in key regulatory tissues, that is, hypothalamus, pancreas, epididymal white adipose tissue (WAT), liver and soleus muscle, over the development of metabolic dysfunctions in OE-NPYDβH mice. The effects of a 5-week treatment with the CB1 receptor inverse agonist AM251 on adiposity and glucose metabolism were studied. Results: 2-AG levels were increased in the hypothalamus and epididymal WAT of pre-obese and obese OE-NPYDβH mice. Anandamide levels in adipose tissue and pancreas were increased at 4 months concomitantly with higher fat mass and impaired glucose tolerance. CB1 receptor blockage reduced body weight gain and glucose intolerance in OE-NPYDβH to the level of vehicle-treated wild-type mice. Conclusions: Altered endocannabinoid tone may underlie some of the metabolic dysfunctions in OE-NPYDβH mice, which can be attenuated with CB1 inverse agonism suggesting interactions between endocannabinoids and NPY also in the periphery. CB1 receptors may offer a target for the pharmacological treatment of the metabolic syndrome with altered NPY levels.

Mixl1 is a member of the Mix/Bix family of paired-like homeodomain proteins and is required for proper axial mesendoderm morphogenesis and endoderm formation during mouse development. Mix/Bix proteins are transcription factors that function in Nodal-like signaling pathways and are themselves regulated by Nodal. Here, we show that Foxh1 forms a DNA-binding complex with Smads to regulate transforming growth factor beta (TGFbeta)/Nodal-dependent Mixl1 gene expression. Whereas Foxh1 is commonly described as a transcriptional activator, we observed that Foxh1-null embryos exhibit expanded and enhanced Mixl1 expression during gastrulation, indicating that Foxh1 negatively regulates expression of Mixl1 during early mouse embryogenesis. We demonstrate that Foxh1 associates with the homeodomain-containing protein Goosecoid (Gsc), which in turn recruits histone deacetylases to repress Mixl1 gene expression. Ectopic expression of Gsc in embryoid bodies represses endogenous Mixl1 expression and this effect is dependent on Foxh1. As Gsc is itself induced in a Foxh1-dependent manner, we propose that Foxh1 initiates positive and negative transcriptional circuits to refine cell fate decisions during gastrulation.

We have previously shown that treatment of Zucker rats and mice with diet-induced obesity with dietary docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids in the form of krill oil reduces peripheral levels of endocannabinoids, ectopic fat formation and hyperglycemia. We reported that such treatment reduces plasma endocannabinoid levels also in overweight and obese human individuals, in whom high triglycerides may correlate with high circulating endocannabinoid levels. In this study, we report the effects of krill powder, which contains proteins (34%) in addition to krill oil (61.8%), on these two parameters. We submitted 11 obese men (average BMI of 32.3 kg/m2, age of 42.6 years and plasma triglycerides of 192.5 ± 96.3 mg/dl) to a 24 week dietary supplementation with krill powder (4 g/day per os) and measured anthropometric and metabolic parameters, as well as blood endocannabinoid (anandamide and 2-arachidonoylglycerol) and esterified DHA and EPA levels. Six subjects were included as control subjects and not given any supplements. The treatment produced, after 12 and 24 weeks, a significant increase in DHA and EPA in total plasma, a 59 and 84% decrease in anandamide plasma levels, and a 22.5 and 20.6% decrease in triglyceride levels, respectively. There was also a significant decrease in waist/hip ratio and visceral fat/skeletal muscle mass ratio at 24 weeks, but no change in body weight. These data confirm that dietary krill powder reduces peripheral endocannabinoid overactivity in obese subjects, and might ameliorate some parameters of the metabolic syndrome.

Background: Cannabinoid type-1 (CB1) receptor inverse agonists improve type 2 diabetes and dyslipidaemia but were discontinued due to adverse psychiatric effects. Δ9-Tetrahydrocannabivarin (THCV) is a neutral CB1 antagonist producing hypophagia and body weight reduction in lean mice. We investigated its effects in dietary-induced (DIO) and genetically (ob/ob) obese mice. Methods: We performed two dose-ranging studies in DIO mice; study 1: 0.3, 1, 2.5, 5 and 12.5 mg kg−1, oral twice daily for 30 days and study 2: 0.1, 0.5, 2.5 and 12.5 mg kg−1, oral, once daily for 45 days. One pilot (study 3: 0.3 and 3 mg kg−1, oral, once daily) and one full dose-ranging (study 4: 0.1, 0.5, 2.5 and 12.5 mg kg−1, oral, once daily) studies in ob/ob mice for 30 days. The CB1 inverse agonist, AM251, oral, 10 mg kg−1 once daily or 5 mg kg−1 twice daily was used as the positive control. Cumulative food and water intake, body weight gain, energy expenditure, glucose and insulin levels (fasting or during oral glucose tolerance tests), plasma high-density lipoprotein and total cholesterol, and liver triglycerides were measured. HL-5 hepatocytes or C2C12 myotubes made insulin-resistant with chronic insulin or palmitic acid were treated with 0, 1, 3 and 10 μM THCV or AM251. Results: THCV did not significantly affect food intake or body weight gain in any of the studies, but produced an early and transient increase in energy expenditure. It dose-dependently reduced glucose intolerance in ob/ob mice and improved glucose tolerance and increased insulin sensitivity in DIO mice, without consistently affecting plasma lipids. THCV also restored insulin signalling in insulin-resistant hepatocytes and myotubes. Conclusions: THCV is a new potential treatment against obesity-associated glucose intolerance with pharmacology different from that of CB1 inverse agonists/antagonists.

The endocannabinoids 2-arachidonoyl-glycerol and N-arachidonoyl-ethanolamine are lipids regulating many physiological processes, notably inflammation. Endocannabinoid hydrolysis inhibitors are now being investigated as potential anti-inflammatory agents. In addition to 2-arachidonoyl-glycerol and N-arachidonoyl-ethanolamine, the endocannabinoidome also includes other monoacylglycerols and N-acyl-ethanolamines such as 1-linoleoyl-glycerol (1-LG) and N-linoleoyl-ethanolamine (LEA). By increasing monoacylglycerols and/or N-acyl-ethanolamine levels, endocannabinoid hydrolysis inhibitors will likely increase the levels of their metabolites. Herein, we investigated whether 1-LG and LEA were substrates for the 15-lipoxygenase pathway, given that both possess a 1Z,4Z-pentadiene motif, near their omega end. We thus assessed how human eosinophils and neutrophils biosynthesized the 15-lipoxygenase metabolites of 1-LG and LEA. Linoleic acid (LA), a well-documented substrate of 15-lipoxygenases, was used as positive control. N-13-hydroxy-octodecadienoyl-ethanolamine (13-HODE-EA) and 13-hydroxy-octodecadienoyl-glycerol (13-HODE-G), the 15-lipoxygenase metabolites of LEA and 1-LG, were synthesized using Novozym 435 and soybean lipoxygenase. Eosinophils, which express the 15-lipoxygenase-1, metabolized LA, 1-LG, and LEA into their 13-hydroxy derivatives. This was almost complete after five minutes. Substrate preference of eosinophils was LA &gt, LEA &gt, 1-LG in presence of 13-HODE-G hydrolysis with methyl-arachidonoyl-fluorophosphonate. Human neutrophils also metabolized LA, 1-LG, and LEA into their 13-hydroxy derivatives. This was maximal after 15–30 s. Substrate preference was LA ≫ 1-LG &gt, LEA. Importantly, 13-HODE-G was found in humans and mouse tissue samples. In conclusion, our data show that human eosinophils and neutrophils metabolize 1-LG and LEA into the novel endogenous 15-lipoxygenase metabolites 13-HODE-G and 13-HODE-EA. The full biological importance of 13-HODE-G and 13-HODE-EA remains to be explored.