Leptin mRNA Levels Research Articles

Interleukin-6 gene knockout antagonizes high-fat-induced trabecular bone loss

The purpose of the study was to determine the roles of interleukin-6 (IL6) in fat and bone communication. Male wild-type (WT) mice and IL6 knockout (IL6(-/-)) mice were fed with either regular diet (RD) or high-fat diet (HFD) for 12 weeks. Bone mass and bone microstructure were evaluated by micro-computed tomography. Gene expression related to lipid and bone metabolisms was assayed with real-time quantitative polymerase chain reaction. Bone marrow cells from both genotypes were induced to differentiate into osteoblasts or osteoclasts, and treated with palmitic acid (PA). HFD increased the body weight and fat pad weight, and impaired lipid metabolism in both WT and IL6(-/-) mice. The dysregulation of lipid metabolism was more serious in IL6(-/-) mice. Trabecular bone volume fraction, trabecular bone number and trabecular bone thickness were significantly downregulated in WT mice after HFD than those in the RD (P < 0.05). However, these bone microstructural parameters were increased by 53%, 34% and 40%, respectively, in IL6(-/-) mice than those in WT mice on the HFD (P < 0.05). IL6(-/-) osteoblasts displayed higher alkaline phosphatase (ALP) activity and higher mRNA levels of Runx2 and Colla1 than those in WT osteoblasts both in the control and PA treatment group (P < 0.05). IL6(-/-) mice showed significantly lower mRNA levels of PPARγ and leptin and higher mRNA levels of adiponectin in comparison with WT mice on HFD. In conclusion, these findings suggested that IL6 gene deficiency antagonized HFD-induced bone loss. IL6 might bridge lipid and bone metabolisms and could be a new potential therapeutic target for lipid metabolism disturbance-related bone loss.

Protective Effects of Chaihu Shugan San () on Nonalcoholic Fatty Liver Disease in Rats with Insulin Resistance.

To investigate the protective effects of Chinese medicine formulation Chaihu Shugan San (, CHSGS) on nonalcoholic fatty liver disease (NAFLD) in rats with insulin resistance (IR) and its molecular mechanisms. Male Sprague-Dawley rats were randomly divided into six groups: the control group, the model group, Dongbao Gantai group (, DBGT, 0.09 g methionine/kg), CHSGS high-dose group (CHSG-H, 12.6 g crude drug/kg), CHSGS medium-dose group (CHSG-M, 6.3 g crude drug/kg), and CHSGS low-dose group (CHSG-L, 3.15 g crude drug/kg). After establishing the NAFLD rat model and treatment for 8 weeks, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), free fatty acid (FFA), fasting blood glucose (FBG), fasting insulin (FINS) contents in blood serum, and TC, TG contents in the hepatic homogenate were measured by an automatic biochemical analyzer, and a homeostasis model assessment was applied to assess the status of IR, insulin sensitivity index (ISI), and homeostasis model assessment for insulin secretion (HOMA-IS). The expression levels of adiponectin and leptin mRNA in liver tissue were analyzed by reverse transcription polymerase chain reaction. Pathological changes of livers were observed by hematoxylin-eosin staining of paraffin section. Compared with the model group, the serum levels of TC, TG, FFA, FBG, FINS, IRI, ISI, and the liver levels of TC and TG in CHSG-H, CHSG-M, CHSG-L groups showed significant declines (P<0.01 or P<0.05); the serum levels of HDL-C, HOMA-IS were significantly increased (P<0.01 or P<0.05); the expression of leptin mRNA was dramatically decreased and the expression of adiponectin mRNA was increased in the hepatic tissue (P<0.01 or P<0.05). The fatty deposition of liver cells could also be alleviated. CHSGS could up-regulate the expression of adiponectin mRNA and down-regulate the expression of leptin mRNA on the liver, suggesting the CHSGS had positive therapeutic effect on NAFLD in rats with IR.

Low-Dose Bisphenol-A Impairs Adipogenesis and Generates Dysfunctional 3T3-L1 Adipocytes.

Environmental endocrine disruptors (EDCs), including bisphenol-A (BPA), have been recently involved in obesity and diabetes by dysregulating adipose tissue function. Our aim was to examine whether prolonged exposure to low doses of BPA could affect adipogenesis and adipocyte metabolic functions. Therefore, 3T3-L1 pre-adipocytes were cultured for three weeks with BPA 1nM to mimic human environmental exposure. We evaluated BPA effect on cell proliferation, differentiation, gene expression and adipocyte metabolic function. BPA significantly increased pre-adipocyte proliferation (p<0.01). In 3T3-L1 adipocytes differentiated in the presence of BPA, the expression of Peroxisome proliferator-activated receptor gamma (PPARγ), Fatty Acid Binding Protein 4/Adipocyte Protein 2 (FABP4/AP2) and CCAAT/enhancer binding protein (C/EBPα) was increased by 3.5, 1.5 and 3 folds, respectively. Mature adipocytes also showed a significant increase in lipid accumulation (p<0.05) and alterations of insulin action, with significant reduction in insulin-stimulated glucose utilization (p<0.001). Moreover, in mature adipocytes, mRNA levels of Leptin, interleukin-6 (IL6) and interferon-γ (IFNγ) were significantly increased (p<0.05). In conclusion, BPA prolonged exposure at low doses, consistent with those found in the environment, may affect adipocyte differentiation program, enhancing pre-adipocyte proliferation and anticipating the expression of the master genes involved in lipid/glucose metabolism. The resulting adipocytes are hypertrophic, with impaired insulin signaling, reduced glucose utilization and increased pro-inflammatory cytokine expression. Thus, these data supported the hypothesis that BPA exposure, during critical stages of adipose tissue development, may cause adipocyte metabolic dysfunction and inflammation, thereby increasing the risk of developing obesity-related diseases.

Compared to casein, bovine lactoferrin reduces plasma leptin and corticosterone and affects hypothalamic gene expression without altering weight gain or fat mass in high fat diet fed C57/BL6J mice.

BackgroundSeveral studies in both humans and rodents have examined the use of lactoferrin as a dietary solution to weight gain and visceral fat accretion and have shown promising results in the short term (up to 7 weeks). This study examined the effects of giving lactoferrin over a longer period of time.MethodsFor 13 weeks, male C57/BL6J mice were given a diet containing 10 % kJ fat and 20 % kJ casein (LFD) or a diet with 45 % kJ fat and either 20 % kJ casein (HFD) or 20 % kJ lactoferrin (HFD + Lac). Physiological, metabolic, and biochemical parameters were investigated. Gene expression was investigated by Real-Time PCR and microarray. All data was assessed using t-test, ANOVA or ANCOVA. Gene Set Enrichment Analysis was used to interpret microarray data and assess the impact on gene sets with common biological roles.ResultsBy the end of the trial, HFD + Lac fed mice did not alter energy balance, body composition, bodyweight, or weight gain when compared to the HFD group. Notably, there were no changes in subcutaneous or epididymal adipose leptin mRNA levels between high fat diet groups, however plasma leptin was significantly reduced in the HFD + Lac compared to HFD group (P < 0.05) suggesting reduced leptin secretion. Global microarray analysis of the hypothalamus indicate an overall reduction in gene sets associated with feeding behaviour (P < 0.01) and an up-regulation of gene sets associated with retinol metabolism in the HFD + Lac group compared to the HFD group (P < 0.01). Genes in the latter catergory have been shown to impact on the hypothalamic-pituitary-adrenal axis. Notably, plasma corticosterone levels in the HFD + Lac group were reduced compared to the HFD fed mice (P < 0.05).ConclusionsThe data suggests that prolonged feeding of full-length dietary lactoferrin, as part of a high fat diet, does not have a beneficial impact on weight gain when compared to casein. However, its impact on leptin secretion and accompanying changes in hypothalamic gene expression may underlie how this dietary protein alters plasma corticosterone. The lactoferrin fed mouse model could be used to identify leptin and corticosterone regulated genes in the hypothalamus without the confounding effects of body weight change.Electronic supplementary materialThe online version of this article (doi:10.1186/s12986-015-0049-7) contains supplementary material, which is available to authorized users.

Molecular cloning of feline resistin and the expression of resistin, leptin and adiponectin in the adipose tissue of normal and obese cats.

Resistin, one of the adipokines that has a cycteine-rich C-terminus, is considered to relate to the development of insulin resistance in rats. However, in cats, there is little knowledge regarding resistin. In this study, we cloned the feline resistin cDNA from adipose tissue by RT-PCR. The feline resistin clone contained an entire open reading frame encoding 107 amino acids that had 72.8%, 75.4%, 50.9% and 51.8% homology with bovine, human, mouse and rat homologues, respectively. In both subcutaneous and visceral adipose tissues, the transcription levels of feline resistin mRNA were significantly higher in obese cats than normal cats, and those of feline adiponectin mRNA were significantly lower in obese cats than normal cats. However, there was no difference in the expression of feline leptin between normal and obese cats. On the other hand, in both normal and obese cats, there were no significant differences in resistin, leptin and adiponectin mRNA levels between subcutaneous and visceral adipose tissues. In cats, the altered expression of resistin and adiponectin mRNA with obesity may contribute to the pathogenesis of insulin resistance and subsequent diabetes mellitus. In addition to feline adiponectin, the feline resistin cDNA clone obtained in this study will be useful for further investigation of the pathogenesis of obesity in cats.

Bovine serum albumin as the dominant form of dietary protein reduces subcutaneous fat mass, plasma leptin and plasma corticosterone in high fat-fed C57/BL6J mice.

Increasing evidence suggests that the source of dietary protein can have an impact on weight gain and fat mass during high-fat feeding in both humans and rodents. The present study examined whether dietary bovine serum albumin (BSA) as the dominant source of protein alters energy balance and adiposity associated with high-fat feeding. C57/BL6J mice were given a diet with 10 % of energy from fat and 20 % of energy from casein or a diet with 45 % of energy from fat and either 20 % of energy from casein (HFD) or BSA (HFD+BSA) for 13 weeks. The HFD+BSA diet did not significantly alter daily energy expenditure, locomotor activity and RER, but did increase cumulative energy intake and percentage of lean mass while reducing feed efficiency and percentage of fat mass when compared with the HFD (P< 0·05). In subcutaneous adipose tissue (SAT), the HFD+BSA diet increased the mRNA levels of PPARα (PPARA), carnitine palmitoyltransferase 1b (CPT1b) and uncoupling protein 3 (UCP3), but reduced the mRNA level of leptin when compared with the HFD (P< 0·05). The SAT mRNA levels of PPARA, CPT1b and UCP3 were negatively correlated (P< 0·05) with SAT mass, which was reduced in HFD+BSA mice compared with HFD controls (P< 0·01). No differences in epididymal fat mass existed between the groups. The HFD+BSA diet normalised plasma leptin and corticosterone levels compared with the HFD (P< 0·05). While differences in leptin levels were associated with the percentage of fat mass (P< 0·01), changes in corticosterone concentrations were independent of the percentage of fat mass (P< 0·05). The data suggest that the HFD+BSA diet influences plasma leptin levels via SAT mass reduction where mRNA levels of genes linked to β-oxidation were increased, whereas differences in plasma corticosterone levels were not related to fat mass reduction.

Effects of Pueraria lobata Root Ethanol Extract on Adipogenesis and Lipogenesis During 3T3-L1 Differentiation into Adipocytes.

We evaluated the inhibitory effect of Pueraria lobata root ethanol extract (PLREE) on lipid accumulation during 3T3-L1 differentiation to adipocytes by measuring the intracellular expression of adipogenic, lipogenic, and lipolytic markers and lipid accumulation. The total polyphenol and flavonoid content of PLREE were 47 and 29 mg/g, respectively. The electron donating capacity of PLREE at 1,000 μg/mL was 48.8%. Treatment of 3T3-L1 preadipocytes with 100, 250, or 500 μg/mL PLREE for 8 days dose-dependently promoted the differentiation of 3T3-L1 cells. In contrast, the lipid content of PLREE-treated cells was significantly reduced by 7.8% (p < 0.05), 35.6% (p < 0.001), and 42.2% (p < 0.001) following treatment with 100, 250, and 500 μg/mL PLREE, respectively, as compared to differentiated control cells. PLREE upregulated peroxisome proliferator-activated receptor γ mRNA and protein, and sterol regulator element-binding protein-1c mRNA levels, but did not affect CCAAT/enhancer binding-protein β and α mRNA levels. PLREE also downregulated acetyl-CoA carboxylase mRNA and protein, fatty acid synthase (FAS) protein, and leptin mRNA levels, but did not affect FAS mRNA expression. PLREE upregulated adipose triglyceride lipase mRNA and protein expression, and hormone-sensitive lipase (HSL) protein expression, but did not affect HSL mRNA expression. In conclusion, we found that PLREE enhanced adipogenesis, but reduced lipogenesis, resulting in decreased lipid accumulation in 3T3-L1 cells.

Chronic cortisol and the regulation of food intake and the endocrine growth axis in rainbow trout.

To gain a better understanding of the mechanisms by which cortisol suppresses growth during chronic stress in fish, we characterized the effects of chronic cortisol on food intake, mass gain, the expression of appetite-regulating factors, and the activity of the GH/IGF axis. Fish given osmotic pumps that maintained plasma cortisol levels at ∼70 or 116 ng/ml for 34 days were sampled 14, 28 and 42 days post-implantation. Relative to shams, the cortisol treatments reduced food intake by 40-60% and elicited marked increases in liver leptin (lep-a1) and brain preoptic area (POA) corticotropin-releasing factor (crf) mRNA levels. The cortisol treatments also elicited 40-80% reductions in mass gain associated with increases in pituitary gh, liver gh receptor (ghr), liver igfI and igf binding protein (igfbp)-1 and -2 mRNA levels, reduced plasma GH and no change in plasma IGF1. During recovery, while plasma GH and pituitary gh, liver ghr and igfI gene expression did not differ between treatments, the high cortisol-treated fish had lower plasma IGF1 and elevated liver igfbp1 mRNA levels. Finally, the cortisol-treated fish had higher plasma glucose levels, reduced liver glycogen and lipid reserves, and muscle lipid content. Thus, our findings suggest that the growth-suppressing effects of chronic cortisol in rainbow trout result from reduced food intake mediated at least in part by increases in liver lep-a1 and POA crf mRNA, from sustained increases in hepatic igfbp1 expression that reduce the growth-promoting actions of the GH/IGF axis, and from a mobilization of energy reserves.

1,25-Dihydroxyvitamin D regulates expression of the tryptophan hydroxylase 2 and leptin genes: implication for behavioral influences of vitamin D

To investigate vitamin D-related control of brain-expressed genes, candidate vitamin D responsive elements (VDREs) at -7/-10 kb in human tryptophan hydroxylase (TPH)2 were probed. Both VDREs bound the vitamin D receptor (VDR)-retinoid X receptor (RXR) complex and drove reporter gene transcription in response to 1,25-dihydroxyvitamin D3 (1,25D). Brain TPH2 mRNA, encoding the rate-limiting enzyme in serotonin synthesis, was induced 2.2-fold by 10 nM 1,25D in human U87 glioblastoma cells and 47.8-fold in rat serotonergic RN46A-B14 cells. 1,25D regulation of leptin (Lep), encoding a serotoninlike satiety factor, was also examined. In mouse adipocytes, 1,25D repressed leptin mRNA levels by at least 84%, whereas 1,25D induced leptin mRNA 15.1-fold in human glioblastoma cells. Chromatin immunoprecipitation sequencing analysis of the mouse Lep gene in response to 1,25D revealed a cluster of regulatory sites (cis-regulatory module; CRM) at -28 kb that 1,25D-dependently docked VDR, RXR, C/EBPβ, and RUNX2. This CRM harbored 3 VDREs and single C/EBPβ and RUNX2 sites. Therefore, the expression of human TPH2 and mouse Lep are governed by 1,25D, potentially via respective VDREs located at -7/-10 kb and -28 kb. These results imply that vitamin D affects brain serotonin concentrations, which may be relevant to psychiatric disorders, such as autism, and may control leptin levels and affect eating behavior.

587. MiRNA-92a Is Involved in the Regulation of Adipose-Derived Stromal Cell (ADSC) Angiogenic Properties

Reparative and regenerative processes after tissue damage are strongly dependent on successful restoration of vascular network. Mesenchymal stem/stromal cells (MSC) including ADSC located within the vessel wall and closely interacted with endothelial cells appear to be key regulators of angiogenesis and regeneration in adult tissues. Mechanisms of MSC ability to stimulate blood vessel growth and remodeling are extensively studying during last decades. microRNAs (miRs), small noncoding RNAs that regulate gene expression by binding to target mRNAs reducing their stability and/or inhibiting translation, play an important role in MSC regulation. It was demonstrated that miR-92a expressed in endothelial cells was induced in ischemia and involved in the regulation of angiogenesis and vessel patterning. We studied miR-92a impact in ADSC angiogenic properties regulation.ADSC were isolated from subcutaneous fat tissue of healthy young donors (n=4) and cultured up to 2-3 passages. ADSC phenotype characterized by flow cytometry was CD90+/CD73+/CD105+/CD45-/CD31- for all samples and these cells were capable of adipogenic and osteogenic differentiation. We analyzed miR profile in ADSC using Illumina microarrays and found that miR-92a was one of the highly expressed miRs in all ADSC samples. ADSC transfection by pre-miR-92a or anti-miR-92a led to the coordinated changes of miR-92a well-known target genes expression (integrin alpha 5, ITGA5, and mitogen activated protein kinase, MEK4). ADSC with over-expression of miR-92a completely lost the ability to stimulate capillary-like tube formation by endothelial cells (HUVEC) in vitro compared to ADSC transfected by the control gene. However, transfection of ADSC by anti-miR-92a did not significantly increase their stimulating effect in tube formation assay. As paracrine mechanisms are considered to be the most important for realizing of MSC angiogenic potential, we analyzed gene expression (qRT-PCR) and secretion (Bio-Plex assay and ELISA) of some key angiogenic factors in ADSC. We found that mRNA level of vascular endothelial growth factor (VEGF), angiogenin and leptin was slightly increased in ADSC transfected by anti-miR-92a and this tendency was also observed for VEGF secretion. When miR-92a was over-expressed in ADSC secretion of hepatocyte growth factor (HGF) and angiopoetin-1 by these cells significantly decreased compared to the control cells.We conclude that miR-92a might play an important role in the regulation of ADSC ability to stimulate angiogenesis and key angiogenic factors such as VEGF, HGF and angiopoetin-1 are involved in this process. The underlying mechanisms of miR-92a-mediated direct or indirect effects in ADSC need to be further investigated. Anyway, miR-92a could be considered as a promising target for the modulation of ADSC angiogenic potential.

Oral Metformin Treatment Counteracts Adipoinsular Axis Dysfunction in Hypothalamic Obese Rats.

Rats neonatally treated with monosodium L-glutamate (MSG) are deeply dysfunctional in adulthood. We explored the effect of an oral low dose of metformin treatment in male MSG rats on adipoinsular axis and visceral adipose tissue (VAT) dysfunctions, in both basal (nonfasting) and endotoxemia conditions. MSG rats, treated or not treated with metformin (30 days prior to experimentation), and control litter-mates (CTR) were studied at 90 days of age. Peripheral concentrations of glucose, lipids, and hormones were determined in basal and post-lipopolysaccharide (LPS) treatment conditions. Food intake and body weight (BW) were recorded and VAT mass and leptin mRNA levels were evaluated. Data indicated that MSG rats were lighter and displayed hypercorticosteronemia, hypophagia, adipoinsular axis hyperactivity, and enhanced VAT mass associated with an increased leptin gene expression. Interestingly, metformin-treated MSG rats corrected BW catch-up and counteracted VAT (mass and leptin mRNA level) and adipoinsular axis (basal and post-LPS) dysfunctions. Thus metformin treatment in MSG rats is able to correct several VAT and metabolic-endocrine dysfunctions. Our study suggests that a low-dose metformintherapy is effective to correct, at least in part, adipoinsular axis dysfunction in hypertrophic obese phenotypes, such as that of the human Cushing syndrome.

Leptin as a Mediator of Tumor‐Stromal Interactions Promotes Breast Cancer Stem Cell Activity.

Breast cancer stem‐like cells (BCSC) are responsible for tumor initiation, maintenance, and metastases. BCSC rely for their properties on complex interactions with the tumor microenvironment through networks of cytokines and growth factors. Leptin, a well‐known cytokine involved in breast cancer progression, plays a crucial role in the tumor‐stromal crosstalk. Thus, we investigated how tumor microenvironmental factors and especially leptin may affect BCSC activity using MCF‐7 breast cancer cells and patient‐derived samples.Treatment of mammosphere cultures with conditioned media (CM) from cancer associated fibroblasts and breast adipocytes resulted in a significant increase in mammosphere‐forming efficiency (MFE). Depletion of leptin from stromal cell‐CM completely abrogated this effect. Accordingly, mammosphere cultures exhibited increased leptin receptor expression and leptin exposure enhanced MFE. Microarray analyses revealed a similar expression profile of genes involved in stemness and cell proliferation in mammospheres treated with stromal cell‐CM and leptin. Finally, leptin significantly increased MFE in patient‐derived samples (metastatic ascites and pleural effusion fluid) and leptin mRNA levels in peritumoral adipose tissue of breast cancer patients were positively correlated with MFE (r= 0.449; P 蠄 0.05).Our study highlights leptin as an important paracrine molecule that mediates the microenvironment effects on BCSC activity.

Bisphenol A disrupts gene expression in human placental trophoblast cells.

This study examined the effect of bisphenol A (BPA) on human placental gene expression using primary trophoblast cells as an in vitro model system. Trophoblast cells were isolated from human placentas at term, cultured and then exposed to environmentally relevant concentrations of BPA (0.1-2 μg/ml) for up to 24h, after which levels of 11β-HSD2 mRNA, protein and activity were determined by standard radiometric conversion assay, western blotting, and qRT-PCR, respectively. The mRNA levels of several other prominent placental hormones/factors were also assessed by qRT-PCR. BPA dramatically increased levels of 11β-HSD2 activity, protein and mRNA in a time- and concentration-dependent manner (> 4-fold). BPA also augmented aromatase, glucose transporter-1, CRH, and hCG mRNA levels while reducing the level of leptin mRNA. These findings demonstrate that BPA severely disrupts human placental gene expression in vitro, which suggests that exposure to BPA may contribute to altered placental function and consequent pregnancy complications.

Esophageal adenocarcinoma and obesity: peritumoral adipose tissue plays a role in lymph node invasion.

Obesity is associated with cancer risk in esophageal adenocarcinoma (EAC). Adipose tissue directly stimulates tumor progression independently from body mass index (BMI), but the mechanisms are not fully understood. We studied the morphological, histological and molecular characteristics of peritumoral and distal adipose tissue of 60 patients with EAC, to investigate whether depot-specific differences affect tumor behavior. We observed that increased adipocyte size (a hallmark of obesity) was directly associated with leptin expression, angiogenesis (CD31) and lymphangiogenesis (podoplanin); however, these parameters were associated with nodal metastasis only in peritumoral but not distal adipose tissue of patients. We treated OE33 cells with conditioned media (CM) collected from cultured biopsies of adipose tissue and we observed increased mRNA levels of leptin and adiponectin receptors, as well as two key regulator genes of epithelial-to-mesenchymal transition (EMT): alpha-smooth muscle actin (α-SMA) and E-cadherin. This effect was greater in cells treated with CM from peritumoral adipose tissue of patients with nodal metastasis and was partially blunted by a leptin antagonist. Therefore, peritumoral adipose tissue may exert a direct effect on the progression of EAC by secreting depot-specific paracrine factors, and leptin is a key player in this crosstalk.

Seasonal changes in body mass, serum leptin levels and hypothalamic neuropeptide gene expression in male Eothenomys olitor

The present study examined seasonal changes in body mass and energy metabolism in the Chaotung vole (Eothenomys olitor) and the physiological mechanisms underpinning these changes. Seasonal changes in the following parameters were measured in male E. olitor, body mass, food intake, thermogenesis, enzyme activity, masses of tissues and organs, hormone concentrations and expression of hypothalamic arcuate nucleus energy balance genes including neuropeptide Y (NPY), agouti-related protein (AgRP), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART). Body mass was constant over the year, but the masses of tissues and organs differed significantly between seasons. There were significant changes in body fat mass and serum leptin levels over the four seasons. E. olitor showed significant seasonal changes in food intake and thermogenesis, uncoupling protein 1 (UCP1) content, enzyme activity, and serum tri-iodothyronine (T3) and thyroxine (T4) levels. Moreover, mRNA expression in the hypothalamus showed significant seasonal changes. All of our results suggested that E. olitor had constant body mass over the year, which was inconsistent with the prediction of the ‘set-point’ hypothesis. However, body fat mass and serum leptin levels were significantly different among the four seasons, providing support for the ‘set-point’ hypothesis. The changes in leptin, NPY, AgRP, POMC, and CART mRNA levels may play a role in the regulation of energy intake in E. olitor. Furthermore, the role of leptin and hypothalamic neuropeptide gene in the regulation of energy metabolism and body mass may be different in animals that are acclimated to different seasons.

Effects of adipocyte-secreted factors on decidualized endometrial cells: modulation of endometrial receptivity in vitro.

Obesity is defined as an excessive accumulation of adipose tissue that may lead to health complications. Mounting evidence indicates that obesity has a negative impact on fertility. Yet, the link between adipose tissue biology and infertility remains unclear. We aimed to investigate the communication between the adipose tissue and the reproductive system and the importance of this cross talk for the development of a receptive endometrium. To that end, we generated an in vitro model with endometrial and adipocyte cell lines. Sexual hormones, progesterone and estradiol, were used to decidualize endometrial cells and sensitize adipocytes. Decidualization produced a simultaneous increase of adipokine receptors in endometrial cells paralleling changes in their receptivity status. Furthermore, sensitization of 3T3-L1 adipocytes increased mRNA levels of leptin and resistin and decreased the expression of adiponectin and chemerin levels. This was accompanied by increased isoproterenol-induced lipolysis and reduced insulin-stimulated glucose uptake. Lastly, conditioned culture medium of those sensitized adipocytes was used to feed endometrial cells. This treatment resulted in (i) upregulation of genes previously identified as positive regulators of endometrial receptivity, such as leukemia inhibitory factor and glutathione peroxidase 3, and (ii) downregulation of interleukin-15 and mucin1, both genes negatively related with endometrial receptivity. Our results indicate that the endocrine communication between adipose tissue and the reproductive system is bidirectional and stress the importance of the adipose tissue to modulate the reproductive fitness.

Molecular regulation of the expression of leptin by hypoxia in human coronary artery smooth muscle cells

BackgroundLeptin, produced mainly by white adipose tissue, is a hormone that promotes vascular smooth muscle cell (VSMC) migration and proliferation, a process involved in the pathophysiology of atherosclerosis. Leptin expression in human coronary artery smooth cell (HCASMC) is induced by hypoxia. However, our understanding of the process of atherosclerosis in HCASMC is only emerging. Since the mechanisms by which hypoxia regulates leptin in HCASMC are as yet unknown, this study aims to investigate the mechanics of molecular regulation of leptin expression in HCASMC under hypoxia. We subjected cultured HCASMCs to hypoxia for varying periods of time. Through use of different signal pathway inhibitors, we were able to sort out and identify the pathway through which hypoxia-induced leptin expression occurs.ResultsLeptin mRNA and protein levels increased after 2.5% hypoxia for 2-to-4 hours, with earlier expression of angiotensin II (AngII) and reactive oxygen species (ROS). The addition before hypoxia of the c-Jun N-terminal kinase (JNK) pathway inhibitor (SP600125), JNK small interfering RNA (siRNA), AngII receptor blockers (ARBs; losartan), or N-acetyl-L-cysteine (NAC, an ROS scavenger), had the effect of inhibiting JNK phosphorylation and leptin expression. Gel shift assay and luciferase promoter study showed that leptin/activator protein 1 (AP-1) binding and transcriptional activity to the leptin promoter increased after hypoxia, and SP600125, JNK siRNA, losartan, and NAC abolished the binding and transcriptional activity induced by hypoxia. The use of SP600125, JNK siRNA, losartan, and NAC effectively inhibited the binding and transcriptional activity induced by hypoxia. Migration and proliferation, ROS generation, and the presence of leptin in the nuclei of HCASMCs also increased under hypoxia.ConclusionHypoxia in HCASMCs increases leptin expression through the induction of AngII, ROS, and the JNK pathway to enhance atherosclerosis in HCASMCs.Electronic supplementary materialThe online version of this article (doi:10.1186/s12929-014-0109-8) contains supplementary material, which is available to authorized users.

Anti-obesity effect of total phenylpropanoid glycosides from Ligustrum robustum Blume in fatty diet-fed mice via up-regulating leptin

Ethnopharmacological relevanceIn Chinese folk medicine, the leaves of Ligustrum robustum Blume (LR) were commonly used in the treatment of obesity and hyperlipidemia. This study aimed to evaluate the anti-obesity effect and mechanisms of total phenylpropanoid glycosides from Ligustrum robustum Blume (LRTPG) in fatty diet-fed C57BL/6J mice. Materials and methodsC57BL/6J mice were divided randomly into 6 groups, i.e., control, model, positive (Orlistat 0.12g/kg), and LRTPG at three dosages (0.3, 0.6 or 1.2g/kg), respectively. Control mice were fed with standard diet; the others were fed with fatty diet. After 4 weeks׳ modeling, therapy mice were intragastrically administrated with positive drug or LRTPG for 5 weeks, respectively. Pharmacodynamic effects including body weight, fat weight, Lee׳s index, serum lipid levels, morphological changes and adipocyte area ratio were evaluated. The mechanisms were explored as the factors related to lipids metabolism in gene expressions by real-time PCR, and assured as the protein level of differential gene by Western blotting. ResultsThe anti-obesity effects of LRTPG in all treated mice were shown as decreased body weight, fat mass, Lee׳s index, total cholesterol (TC) level, and adipocyte area. The mechanisms were demonstrated as elevated mRNA and protein levels of adipose leptin, and consequently decreasing mRNA of adipose acyl coenzyme A: diacylglycerol acyltransferase (DGAT) with increasing mRNA of hepatic cholesterol 7α-hydroxylase (CYP7A1), which led to inhibition of triglyceride (TG) synthesis and promotion of cholesterol catabolism. ConclusionsThe anti-obesity effect of LRTPG in fatty diet-fed mice was related to the up-regulation of leptin, which may provide scientific evidence supporting the traditional usage of LR on obesity in China.

Leptin and adiponectin mRNA expression from the adipose tissue surrounding the adrenal neoplasia.

Interplay between adipose tissue and adrenal glands has been recently suggested, without well-founded actions of locally adipose tissue surrounding the adrenal glands. We hypothesized that the local expression of leptin and adiponectin can be associated with pathological changes of the adrenal glands. We evaluated RT-PCR of leptin and adiponectin mRNA expression from the adipose tissue surrounding adrenal glands in 30 patients, collecting adipose tissue surrounding the adrenal neoplasms, peri-renal and subcutaneous depots. Leptin mRNA levels from adrenal neoplasia and peri-renal fat were significantly higher in aldosterone-producing adenoma than in nonfunctioning adenomas (P < 0.001 and P < 0.02, respectively). In patients with Cushing's syndrome leptin mRNA levels were significantly higher in adrenal fat than in peri-renal (P < 0.05) and subcutaneous adipose tissue (P < 0.001). Adiponectin mRNA expression from adrenal neoplasia was significantly lower than that from peri-renal and subcutaneous fat depots (P < 0.05). Leptin and adiponectin plasma levels significantly correlated with their mRNA expression from the fat depot surrounding the adrenal neoplasia. Our findings suggest an active role of the fat depot surrounding the adrenal neoplasia, with local secretion of leptin and adiponectin.

Acute Wnt pathway activation positively regulates leptin gene expression in mature adipocytes

Genome-wide association studies (GWAS) have revealed the implication of several Wnt signaling pathway components, including its effector transcription factor 7-like 2 (TCF7L2) in diabetes and other metabolic disorders. As TCF7L2 is expressed in adipocytes, we investigated its expression and function in rodent fat tissue and mature adipocytes. We found that TCF7L2 mRNA expression in C57BL/6 mouse epididymal fat tissue was up-regulated by feeding but down-regulated by intraperitoneal insulin injection. In high-fat diet (HFD) fed mice, db/db mice and Zucker (fa/fa) rats, epididymal fat TCF7L2 mRNA levels were lower than the corresponding controls. Treating rat adipocytes with 100nM insulin repressed TCF7L2 mRNA and protein levels, associated with the repression of leptin mRNA level. The treatment with 1nM insulin, however, stimulated TCF7L2 and leptin mRNA levels. This stimulation could be attenuated by iCRT14, an inhibitor of β-catenin/TCF-responsive transcription. Wnt3a stimulated leptin mRNA level, which was also blocked by iCRT14 co-treatment. Utilizing the leptin-expressing cell line HTR8 as a tool, we defined an evolutionarily conserved CREB binding motif that mediated Wnt3a activation. Although Wnt activation is known to repress the differentiation of 3T3-L1 cells towards mature adipocytes, short-term Wnt3a treatment of differentiated 3T3-L1 cells stimulated leptin mRNA levels. Thus, wnt pathway plays a dual function in adipocytes, including the well-known repressive effect on adipogenesis and the stimulation of leptin production in mature adipocytes in response to nutritional status.