Effects of pioglitazone on adipose tissue remodeling within the setting of obesity and insulin resistance

Browning of white adipose tissue induced by the ß3 agonist CL-316,243 after local and systemic treatment - PK-PD relationship

Transformation of white adipose tissue (WAT) to a brown adipose tissue-like (BAT-like) phenotype has emerged as an attractive approach against obesity e.g. using g ß3 adrenergic receptor agonists. These could however, produce side-effects following systemic exposure. The present study explored the possibility of local use of CL-316,243 - a selective ß3 agonist - to circumvent this problem. Rats treated s.c. for 2 weeks (0.3 and 1 mg/kg) showed decreased inguinal fat pad (IFP) weight/volume, increased UCP-1 staining and expressed BAT-like features in H&E stained micrographs. Interscapular BAT increased in weight/volume. In contrast, local treatment into the IFP was not efficacious in terms of weight/volume, despite slight increases in UCP-1 staining and changes in histological features. After local treatment, the exposure of the IFP was lower than after systemic treatment. In turn higher local doses (0.5 and 5 mg/ml) were then tested which produced a strong trend for decreased volume of the IFP, a significant increase in UCP-1 staining, and also a decrease in adipocytes size but increased number. However, after this treatment the systemic exposure was in the same range as following systemic treatment. In conclusion, we saw no evidence for the possibility of converting inguinal WAT to a BAT-phenotype solely through local activation of ß3 receptors. This is in concert with our in vitro experiments which detected direct effects of PPARγ agonists at the gene/protein expression and functional level, but were unable to detect any effect of CL-316,243.

The CD36-PPARγ Pathway in Metabolic Disorders

Uncovering the biological role of nuclear receptor peroxisome proliferator-activated receptors (PPARs) has greatly advanced our knowledge of the transcriptional control of glucose and energy metabolism. As such, pharmacological activation of PPARγ has emerged as an efficient approach for treating metabolic disorders with the current use of thiazolidinediones to improve insulin resistance in diabetic patients. The recent identification of growth hormone releasing peptides (GHRP) as potent inducers of PPARγ through activation of the scavenger receptor CD36 has defined a novel alternative to regulate essential aspects of lipid and energy metabolism. Recent advances on the emerging role of CD36 and GHRP hexarelin in regulating PPARγ downstream actions with benefits on atherosclerosis, hepatic cholesterol biosynthesis and fat mitochondrial biogenesis are summarized here. The response of PPARγ coactivator PGC-1 is also discussed in these effects. The identification of the GHRP-CD36-PPARγ pathway in controlling various tissue metabolic functions provides an interesting option for metabolic disorders.

In vitro anti-diabetic effect of flavonoids and pheophytins from Allophylus cominia Sw. on the glucose uptake assays by HepG2, L6, 3T3-L1 and fat accumulation in 3T3-L1 adipocytes

BACKGROUND AND PURPOSE

Based on ethno-botanical information collected from diabetic patients in Cuba and firstly reported inhibition of PTP1B and DPPIV enzymes activities, Allophylus cominia (A. cominia) was identified as possible source of new drugs that could be used for the treatment of type 2 diabetes mellitus (T2-DM).

EXPERIMENTAL APPROACH

in this study, the activity of the characterised extracts from A. cominia was tested on the glucose uptake using HepG2 and L6 cells, 3T3-L1 fibroblasts and adipocytes as well as their effect on the fat accumulation using 3T3-L1 adipocytes.

KEY RESULTS

on 2-NBDG glucose uptake assay using HepG2 and L6 cells, extracts from A. cominia enhanced insulin activity by increasing glucose uptake. On HepG2 cells Insulin EC₅₀ of 93 ± 21nM decreased to 13 ± 2nM in the presence of the flavonoids mixture from A.cominia. In L6 cells, insulin also produced a concentration-dependent increase with an EC₅₀ of 28.6 ± 0.7nM; EC₅₀ decreased to 0.08 ± 0.02nM and 5 ± 0.9nM in the presence of 100μg/ml of flavonoids and pheophytins mixtures, respectively. In 3T3-L1 fibroblasts, insulin had an EC₅₀ of >1000nM that decreased to 38 ± 4nM in the presence of the flavonoids extract. However, in adipocytes, insulin produced a significant concentration-dependent increase and an EC₅₀ of 30 ± 8nM was a further confirmation of the insulin responsiveness of the adipocytes to the insulin. At 100µg/ml, flavonoids and pheophytins extracts decreased fat accumulation in 3T3-L1 adipocytes by two folds in comparison to the control differentiated cells (p < 0.05). The crude extract of A. cominia did not show any enhancement of 2-NBDG uptake by 3T3-L1 adipocytes in the presence or absence of 100nM insulin. In addition, in fully differentiated adipocytes, both extracts produced significant decrease in lipid droplets in the cells and no lipid accumulation were seen after withdrawal of the extracts from the cell growth medium. However, there was no effect of both extracts on total protein concentration in cells as well as on Glut-4 transporters.

CONCLUSIONS AND IMPLICATIONS

the pharmacological effects of the extracts from A. cominia observed in experimental diabetic models were shown in this study. A. cominia is potentially a new candidate for the treatment and management of T2-DM.

Egg Protein-Derived Bioactive Peptides: Preparation, Efficacy, and Absorption

The hen's egg is an important protein source of human diet. On average one large egg contains ~6g protein, which contributes to ~11% of daily protein intake. As a high-quality protein, egg proteins are well recognized as excellent sources of bioactive peptides. The objectives of this chapter are to introduce generation, bioactivities, and absorption of egg protein-derived bioactive peptides. Research on egg protein-derived bioactive peptides has been progressed during the past decades. Enzymatic hydrolysis is the major technique to prepare bioactive peptides from egg protein. Quantitative structure-activity relationships-aided in silico prediction is increasingly applied as a promising tool for efficient prediction of novel bioactive peptides. A number of bioactive peptides from egg proteins have been characterized for antioxidant, immunomodulatory, antihypertensive, antidiabetic, anticancer, and antimicrobial activities. Egg protein-derived peptides that can improve bone health have been reported as well. However, molecular mechanisms of many peptides are not fully understood. The stability and absorption routes, bioavailability, safety, and production of bioactive peptides await further investigation.

Polluted Pathways: Mechanisms of Metabolic Disruption by Endocrine Disrupting Chemicals

PURPOSE OF REVIEW

Environmental toxicants are increasingly implicated in the global decline in metabolic health. Focusing on diabetes, herein, the molecular and cellular mechanisms by which metabolism disrupting chemicals (MDCs) impair energy homeostasis are discussed.

RECENT FINDINGS

Emerging data implicate MDC perturbations in a variety of pathways as contributors to metabolic disease pathogenesis, with effects in diverse tissues regulating fuel utilization. Potentiation of traditional metabolic risk factors, such as caloric excess, and emerging threats to metabolism, such as disruptions in circadian rhythms, are important areas of current and future MDC research. Increasing evidence also implicates deleterious effects of MDCs on metabolic programming that occur during vulnerable developmental windows, such as in utero and early post-natal life as well as pregnancy. Recent insights into the mechanisms by which MDCs alter energy homeostasis will advance the field's ability to predict interactions with classical metabolic disease risk factors and empower studies utilizing targeted therapeutics to treat MDC-mediated diabetes.

Egg white hydrolysate shows insulin mimetic and sensitizing effects in 3T3-F442A pre-adipocytes

Insulin resistance and inflammation in adipose tissue is a key mechanism underlying metabolic syndrome, a growing health problem characterized by diabetes, obesity and hypertension. Previous work from our research group has demonstrated the potential of egg white ovotransferrin derived bioactive peptides against hypertension, oxidative stress and inflammation in vitro and in vivo. Egg white hydrolysate (EWH) has also shown anti-hypertensive effects in spontaneously hypertensive rats. Given the interplay among hypertension, inflammation, oxidative stress and metabolic syndrome, the objective of the study was to test the EWH on differentiation, insulin signaling and inflammatory responses in 3T3-F442A pre-adipocytes. Our study suggested that EWH could promote adipocyte differentiation as shown by increased lipid accumulation, increased release of adiponectin and upregulation of peroxisome proliferator associated receptor gamma (PPARγ) and CCAAT/ enhancer binding protein alpha (C/EBP-α). In addition to enhanced insulin effects on the upregulation of protein kinase B/Akt phosphorylation, EWH treatment increased extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation to a level similar to that of insulin, indicating insulin sensitizing and mimetic properties of the EWH. EWH further attenuated cytokine induced inflammatory marker; cyclooxygenase -2 (COX-2) by 48.78%, possibly through the AP-1 pathway by down regulating c-Jun phosphorylation in adipocytes. Given the critical role of adipose in the pathogenesis of insulin resistance and metabolic syndrome, EWH may have potential applications in the prevention and management of metabolic syndrome and its complications.

Comparison of Ipragliflozin and Pioglitazone Effects on Nonalcoholic Fatty Liver Disease in Patients With Type 2 Diabetes: A Randomized, 24-Week, Open-Label, Active-Controlled Trial

OBJECTIVE

To compare the efficacy of ipragliflozin versus pioglitazone in patients with type 2 diabetes complicated by nonalcoholic fatty liver disease (NAFLD).

RESEARCH DESIGN AND METHODS

In this open-label, randomized, active-controlled trial, we randomly assigned 66 patients with type 2 diabetes and NAFLD to receive ipragliflozin 50 mg (n = 32) or pioglitazone 15-30 mg (n = 34) orally once daily. The primary outcome was a change from baseline in the liver-to-spleen attenuation ratio (L/S ratio) on computed tomography at week 24.

RESULTS

At week 24, the mean ± SD L/S ratio had increased by 0.22 (from 0.80 ± 0.24 to 1.00 ± 0.18) in the ipragliflozin group and 0.21 (from 0.78 ± 0.26 to 0.98 ± 0.16) in the pioglitazone group (P = 0.90). Serum aspartate and alanine aminotransferase levels, HbA_1c, and fasting plasma glucose were similarly reduced in the two treatment groups. Nevertheless, body weight and visceral fat area showed significant reductions only in the ipragliflozin group compared with the pioglitazone group (P < 0.0001 and P = 0.0013, respectively). There were no serious adverse events in either group.

CONCLUSIONS

Compared with pioglitazone, ipragliflozin exerts equally beneficial effects on NAFLD and glycemic control during the treatment of patients with type 2 diabetes complicated by NAFLD. Furthermore, ipragliflozin significantly reduced body weight and abdominal fat area.

Impact of pioglitazone and bradykinin type 1 receptor antagonist on type 2 diabetes in high-fat diet-fed C57BL/6J mice

Aim

Type 2 diabetes (T2D) is a major complication of obesity and a leading cause of morbidity and mortality. Antagonizing bradykinin type 1 receptor (B1R) improved body and tissue fat mass and reversed vascular and adipose tissue inflammation in a rat model of insulin resistance. This study aimed at evaluating further the role of B1R in a mouse model of T2D by comparing the antidiabetic and anti‐inflammatory effects of the B1R antagonist SSR240612 (SSR) in adipose tissue with those of pioglitazone (TZD), an activator of peroxisome proliferator‐activated receptor gamma.

Methods

C57BL/6J mice were fed with high‐fat diet (HFD) or standard diet (control) for 20 weeks. Yet, during the last 4 weeks, HFD‐fed mice were administered SSR and TZD (10 mg kg⁻¹ d⁻¹ each) as monotherapy or combined therapy subcutaneously. The impact of treatments was measured on metabolic hormones levels (ELISA), adipose tissue inflammatory status and the expression of candidate genes involved in T2D (quantitative real‐time polymerase chain reaction and western blot).

Results

SSR240612 and TZD treatments improved hyperglycaemia, hyperinsulinaemia, insulin resistance, adipose tissue inflammation (expression of B1R, chemokine ligand 2, F4/80 and tumour necrosis factor) and modulated adipogenesis (peroxisome proliferator‐activated receptor gamma, adipocytes' protein 2 and CD40 expressions) in HFD‐fed mice. Yet, SSR was more effective than TZD to reduce visceral fat mass and resistin. TZD/SSR combined treatment had an additive effect to improve insulin sensitivity and glucose intolerance.

Conclusion

Bradykinin type 1 receptor antagonism could represent a promising therapeutic tool in combination with TZD for the treatment of T2D, obesity and insulin resistance.

PPAR-γ agonist ameliorates liver pathology accompanied by increasing regulatory B and T cells in high-fat-diet mice

OBJECTIVE

Peroxisome proliferator-activated receptor (PPAR)-γ plays critical roles in human metabolic disorders. However, the mechanism remains incompletely understood. Regulatory cells contribute to these metabolic improvements; therefore, whether PPAR-γ agonist regulates regulatory cells was investigated.

METHODS

C57BL/6J mice received a normal or high-fat diet (HFD) with or without pioglitazone treatment. Mice were sacrificed for detecting the metabolic parameters. Lymphocytes from spleen and visceral adipose tissue (VAT) were collected and analyzed for ST2⁺ Tregs and Bregs by flow cytometry. IL-10 in the liver or VAT was detected by immunofluorescence and ELISA. Correlation analysis between IL-10 and liver weight or serum total cholesterol was made by Pearson correlation analysis.

RESULTS

Pioglitazone increased VAT weight but reduced serum total cholesterol, hepatic steatosis, and cholesterol crystallization formation. Pioglitazone treatment enhanced ST2⁺ Tregs and Bregs in the VAT and spleen of HFD-fed mice (all P < 0.05). Pioglitazone treatment increased IL-10 in the livers or VAT of HFD-fed mice (all P < 0.05). The expression of IL-10 in the liver was significantly negatively correlated with liver weight or serum total cholesterol in pioglitazone-treated HFD-fed mice (r²  = 0.74, P < 0.05; r²  = 0.58, P < 0.05).

CONCLUSIONS

PPAR-γ signaling plays a critical role in the regulation of metabolic disorders through promoting regulatory cell response.

Abscisic acid enhances glucose disposal and induces brown fat activity in adipocytes in vitro and in vivo

Abscisic acid (ABA) is a plant hormone also present in animals, where it is involved in the regulation of innate immune cell function and of glucose disposal, through its receptor LANCL2. ABA stimulates glucose uptake by myocytes and pre-adipocytes in vitro and oral ABA improves glycemic control in rats and in healthy subjects. Here we investigated the role of the ABA/LANCL2 system in the regulation of glucose uptake and metabolism in adipocytes. Silencing of LANCL2 abrogated both the ABA- and insulin-induced increase of glucose transporter-4 expression and of glucose uptake in differentiated 3T3-L1 murine adipocytes; conversely, overexpression of LANCL2 enhanced basal, ABA- and insulin-stimulated glucose uptake. As compared with insulin, ABA treatment of adipocytes induced lower triglyceride accumulation, CO2 production and glucose-derived fatty acid synthesis. ABA per se did not induce pre-adipocyte differentiation in vitro, but stimulated adipocyte remodeling in terminally differentiated cells, with a reduction in cell size, increased mitochondrial content, enhanced O2 consumption, increased transcription of adiponectin and of brown adipose tissue (BAT) genes. A single dose of oral ABA (1μg/kg body weight) increased BAT glucose uptake 2-fold in treated rats compared with untreated controls. One-month-long ABA treatment at the same daily dose significantly upregulated expression of BAT markers in the WAT and in WAT-derived preadipocytes from treated mice compared with untreated controls. These results indicate a hitherto unknown role of LANCL2 in adipocyte sensitivity to insulin-stimulated glucose uptake and suggest a role for ABA in the induction and maintenance of BAT activity.

Reduced LPL and subcutaneous lipid storage capacity are associated with metabolic syndrome in postmenopausal women with obesity

OBJECTIVES

This study examines the hypothesis that lower adipose tissue lipoprotein lipase (LPL) activity and a limited capacity for subcutaneous adipocyte expansion will be associated with metabolic syndrome (MSyn) in postmenopausal women who are overweight and obese.

METHODS

Women (N = 150; age 60 ± 1 year; BMI: 31.5 ± 0.3 kg m^-2; mean ± standard errors of the means [SEM]) with and without MSyn had dual-energy X-ray absorptiometry scans for total body fat, CT scans for visceral and subcutaneous abdominal adipose tissue areas, lipid and glucose metabolic profiles, and abdominal and gluteal fat aspirations for subcutaneous fat cell weight (FCW; N = 150) and LPL activity (N = 100).

RESULTS

Women with MSyn had similar total body fat, but 15% larger abdominal and 11% larger gluteal FCWs and more visceral fat (179 ± 7 vs. 134 ± 6 cm²) than women without MSyn (P's < 0.05). Abdominal LPL activity was 13% (P = 0.18) lower in women with than without MSyn and correlated with abdominal FCW (r = 0.49, P < 0.01) only in those without MSyn. Visceral fat and abdominal and gluteal FCWs correlated with MSyn components, and subcutaneous adipose tissue correlated with abdominal FCW (r = 0.43, P < 0.01) and LPL activity (r = 0.18, P < 0.05), independent of total body fat.

CONCLUSIONS

These results show that women with MSyn have lower LPL activity, limited capacity for subcutaneous adipocyte lipid storage and greater ectopic fat accumulation in viscera than women without MSyn of comparable obesity. This suggests that the development of novel therapies that would enhance adipocyte expandability might prevent the accumulation of ectopic fat and reduce the risk for MSyn in postmenopausal women with obesity.

Fermented Barley Supplementation Modulates the Expression of Hypothalamic Genes and Reduces Energy Intake and Weight Gain in Rats

Dietary fiber and proteins are individually known to decrease feeding, but could result greater weight management benefit when both are combined. We hypothesized that supplementing the diet with fermented barley, being rich in both dietary fiber and proteins, could lower energy intake by modulating the mRNA expression level of hypothalamic genes associated with the regulation of feeding behavior and satiety; thereby decreasing body weight gain. To test our hypothesis, four groups of Sprague Dawley rats were arranged in a 2 × 2 factorial design (n = 6), low-fat diet with either guar gum (LFD-G) or fermented barley (LFD-FB) and high-fat diet with either guar gum (HFD-G) or fermented barley (HFD-FB). Using oral gavage, fermented barley was given at a dosage of 1500 mg/kg body weight and guar gum was supplemented in an equivalent quantity to that of the fiber in the fermented barley. After 19 weeks, the fermented barley-supplemented groups showed a significant reduction in energy intake, triglyceride, body weight gain, and serum leptin, compared to the guar gum-supplemented groups in both the low- and high-fat diet groups. Likewise, the anorexigenic gene proopiomelanocortin (POMC) and cocaine and amphetamine-regulated transcript (CART) mRNA level were significantly higher in the fermented barley-supplemented groups compared to the guar gum-supplemented groups in rats fed on both high- and low-fat diets. In conclusion, fermented barley supplementation upregulated hypothalamic POMC/CART, decreased energy intake in both low- and high-fat diet groups, and prevented excessive weight gain in rats.

Impaired glucose tolerance: do pharmacological therapies correct the underlying metabolic disturbance?

Lifestyle intervention prevents or delays the conversion from impaired glucose tolerance (IGT) to type 2 diabetes. However, many subjects fail to achieve and/or maintain long-term weight loss and to follow a regular exercise regimen may require pharmacologic therapy. Insulin resistance in liver, muscle and fat, along with impaired beta-cell function, plays a central role in the pathogenesis of type 2 diabetes. Insulin sensitising drugs, including metformin and the thiazolidinediones, have significantly reduced the conversion rate of IGT to type 2 diabetes in subjects in several large, well designed clinical trials. Insulin-sensitising drugs are likely to play an important role in future strategies for diabetes prevention.

Acute exercise regulates adipogenic gene expression in white adipose tissue

White adipose tissue expansion is associated with both hypertrophy and hyperplasia of adipocytes. Exercise training results in adipocyte hypotrophy by activating lipolysis, but it is poorly understood whether exercise regulates adipogenesis by altering adipogenic gene expression. The purpose of this study was to evaluate the effect of a single bout of swimming exercise on adipogenic gene expression in white adipose tissue (WAT). Male C57BL/6J mice were divided into two groups: a sedentary control group and a 120-minute swimming exercise group. Immediately after acute exercise, adipogenic gene expression in WAT was analysed by RT-PCR, and tdTomato positive cells in WAT from UCP1-cre-tdTomato mice were observed under a confocal microscope. In epididymal white adipose tissue (eWAT), PPARγ2 and C/EBPα expression at the mRNA level was significantly decreased with high induction of Wnt10b and KLFs (KLF2, KLF3, KLF7, KLF6, KLF9 and KLF15), whereas PPARγ2, not C/EBPα, was decreased with high induction of Wnt6 and KLFs (KLF2, KLF3, KLF7, KLF6 and KLF9) in inguinal white adipose tissue (iWAT) after acute exercise. The expression of C/EBPβ and C/EBPδ was upregulated in both WATs with a high level of PGC-1α expression. Expression level of UCP1 was increased only in adipocytes of eWAT, while beige cell specific gene expression was comparable between groups and tdTomato positive cells were not found in WAT of UCP1-cre-tdTomato reporter mouse immediately after acute exercise. These results suggest that acute exercise suppresses adipogenic gene expression and may regulate thermogenesis by activating C/EBPβ, PGC-1α and UCP1 in WAT.

Pleiotropic Actions of Peroxisome Proliferator-Activated Receptors (PPARs) in Dysregulated Metabolic Homeostasis, Inflammation and Cancer: Current Evidence and Future Perspectives

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) have demonstrated a lot of important effects in the regulation of glucose and lipid metabolism and in the correct functioning of adipose tissue. Recently, many studies have evaluated a possible effect of PPARs on tumor cells. The purpose of this review is to describe the effects of PPARs, their action and their future prospective;

METHODS

Narrative review aimed to synthesize cutting-edge evidence retrieved from searches of computerized databases;

RESULTS

PPARs play a key role in metabolic diseases, which include several cardiovascular diseases, insulin resistance, type 2 diabetes, metabolic syndrome, impaired immunity and the increasing risk of cancer; in particular, PPARα and PPARβ/δ mainly enable energy combustion, while PPARγ contributes to energy storage by enhancing adipogenesis;

CONCLUSION

PPAR agonists could represent interesting types of molecules that can treat not only metabolic diseases, but also inflammation and cancer. Additional research is needed for the identification of high-affinity, high-specificity agonists for the treatment of obesity, type 2 diabetes (T2DM) and other metabolic diseases. Further studies are needed also to elucidate the role of PPARs in cancer.

Maternal obesity epigenetically alters visceral fat progenitor cell properties in male offspring mice

KEY POINTS

Maternal obesity reduces adipogenic progenitor density in offspring adipose tissue. The ability of adipose tissue expansion in the offspring of obese mothers is limited and is associated with metabolic dysfunction of adipose tissue when challenged with a high-fat diet. Maternal obesity induces DNA demethylation in the promoter of zinc finger protein 423, which renders progenitor cells with a high adipogenic capacity. Maternal obesity demonstrates long-term effects on the adipogenic capacity of progenitor cells in offspring adipose tissue, demonstrating a developmental programming effect.

ABSTRACT

Maternal obesity (MO) programs offspring obesity and metabolic disorders, although the underlying mechanisms remain poorly defined. Progenitor cells are the source of new adipocytes. The present study aimed to test whether MO epigenetically predisposes adipocyte progenitors in the fat of offspring to adipogenic differentiation and subsequent depletion, which leads to a failure of adipose tissue plasticity under positive energy balance, contributing to adipose tissue metabolic dysfunction. C57BL/6 female mice were fed either a control diet (10% energy from fat) or a high-fat diet (45% energy from fat) for 8 weeks before mating. Male offspring of control (Con) and obese (OB) dams were weaned onto a regular (Reg) or obesogenic (Obe) diet until 3 months of age. At weaning, male OB offspring had a higher expression of Zinc finger protein 423 (zfp423), a key transcription factor in adipogenesis, as well as lower DNA methylation of its promoter in progenitors of epididymal fat compared to Con offspring, which was correlated with enhanced adipogenic differentiation. At 3 months of age, progenitor density was 30.9 ± 9.7% lower in OB/Obe compared to Con/Obe mice, accompanied by a limited expansion of the adipocyte number when challenged with a high-energy diet. This difference was associated with lower DNA methylation in the zfp423 promoter in the epididymal fat of OB/Obe offspring, which was correlated with greater macrophage chemotactic protein-1 and hypoxia-inducible factor 1α expression. In summary, MO epigenetically limits the expansion capacity of offspring adipose tissue, providing an explanation for the adipose metabolic dysfunction of male offspring in the setting of MO.

The Effect of Cumin cyminum L. Plus Lime Administration on Weight Loss and Metabolic Status in Overweight Subjects: A Randomized Double-Blind Placebo-Controlled Clinical Trial

Background

Limited data are available regarding the effects of combined administration of Cumin cyminum L. and lime on weight loss and metabolic profiles among subjects with overweight subjects.

Objectives

The current study aimed to assess the effects of combined administration of Cumin cyminum L. and lime on weight loss and metabolic profiles among subjects with overweight.

Patients and Methods

This randomized double-blind placebo-controlled clinical trial was conducted on 72 subjects with overweight, aged 18 - 50 years old. Participants were randomly divided into three groups: Group A received high-dose Cumin cyminum L. and lime capsules (75 mg each, n = 24), group B low-dose Cumin cyminum L. and lime capsules (25 mg each, n = 24) and group C placebos (n = 24) twice daily for eight weeks.

Results

After eight weeks of intervention, compared with low-dose C. cyminum L. plus lime and placebo, taking high-dose C. cyminum L. plus lime resulted in significant weight loss (in the high-dose group: -2.1 ± 1.7 vs. in the low-dose group: -1.2 ± 1.5 and in the placebo group: + 0.2 ± 1.3 kg, respectively; P < 0.001) and body mass index (-0.8 ± 0.6 vs. -0.5 ± 0.5 and +0.1 ± 0.5 kg/m², respectively; P < 0.001). In addition, administration of high-dose C. cyminum L. plus lime compared with low-dose C. cyminum L. plus lime and placebo, led to a significant reduction in fasting plasma glucose (FPG) (P < 0.001) and a significant rise in quantitative insulin sensitivity check index (QUICKI) (+ 0.02 ± 0.02 vs. + 0.01 ± 0.02 and 0.01 ± 0.01, respectively; P = 0.01). Moreover, a significant decrease in serum triglycerides (-14.1 ± 56.2 vs. +13.9 ± 36.8 and + 10.6 ± 25.1 mg/dL; respectively; P = 0.03), total-cholesterol (-18.4 ± 28.6 vs. +8.6 ± 28.5 and -1.0 ± 24.8 mg/dL; respectively; P = 0.004) and low density lipoproteins- (LDL)-cholesterol levels (-11.8 ± 20.7 vs. +6.5 ± 23.2 and -2.9 ± 20.4 mg/dL, respectively; P = 0.01) was observed following the consumption of high-dose C. cyminum L. plus lime compared with low-dose C. cyminum L. plus lime and placebo.

Conclusions

Results of the current study indicated that taking high-dose C. cyminum L. plus lime for eight weeks among subjects with overweight had beneficial effects on weight, BMI, FPG, QUICKI, triglycerides, total-cholesterol and LDL-cholesterol levels.

Adipose Cell Size and Regional Fat Deposition as Predictors of Metabolic Response to Overfeeding in Insulin-Resistant and Insulin-Sensitive Humans

Obesity is associated with insulin resistance, but significant variability exists between similarly obese individuals, pointing to qualitative characteristics of body fat as potential mediators. To test the hypothesis that obese, insulin-sensitive (IS) individuals possess adaptive adipose cell/tissue responses, we measured subcutaneous adipose cell size, insulin suppression of lipolysis, and regional fat responses to short-term overfeeding in BMI-matched overweight/obese individuals classified as IS or insulin resistant (IR). At baseline, IR subjects exhibited significantly greater visceral adipose tissue (VAT), intrahepatic lipid (IHL), plasma free fatty acids, adipose cell diameter, and percentage of small adipose cells. With weight gain (3.1 ± 1.4 kg), IR subjects demonstrated no significant change in adipose cell size, VAT, or insulin suppression of lipolysis and only 8% worsening of insulin-mediated glucose uptake (IMGU). Alternatively, IS subjects demonstrated significant adipose cell enlargement; decrease in the percentage of small adipose cells; increase in VAT, IHL, and lipolysis; 45% worsening of IMGU; and decreased expression of lipid metabolism genes. Smaller baseline adipose cell size and greater enlargement with weight gain predicted decline in IMGU, as did increase in IHL and VAT and decrease in insulin suppression of lipolysis. Weight gain in IS humans causes maladaptive changes in adipose cells, regional fat distribution, and insulin resistance. The correlation between development of insulin resistance and changes in adipose cell size, VAT, IHL, and insulin suppression of lipolysis highlight these factors as potential mediators between obesity and insulin resistance.

Bavachin from Psoralea corylifolia Improves Insulin-Dependent Glucose Uptake through Insulin Signaling and AMPK Activation in 3T3-L1 Adipocytes

The fruit of Psoralea corylifolia L. (Fabaceae) (PC), known as "Bo-Gol-Zhee" in Korea has been used as traditional medicine. Ethanol and aqueous extracts of PC have an anti-hyperglycemic effect by increasing plasma insulin levels and decreasing blood glucose and total plasma cholesterol levels in type 2 diabetic rats. In this study, we purified six compounds from PC and investigated their anti-diabetic effect. Among the purified compounds, bavachin most potently accumulated lipids during adipocyte differentiation. Intracellular lipid accumulation was measured by Oil Red-O (ORO) cell staining to investigate the effect of compounds on adipogenesis. Consistently, bavachin activated gene expression of adipogenic transcriptional factors, proliferator-activated receptorγ (PPARγ) and CCAAT/enhancer binding protein-α (C/EBPα). Bavachin also increased adiponectin expression and secretion in adipocytes. Moreover, bavachin increased insulin-induced glucose uptake by differentiated adipocytes and myoblasts. In differentiated adipocytes, we found that bavachin enhanced glucose uptake via glucose transporter 4 (GLUT4) translocation by activating the Akt and 5'AMP-activated protein kinase (AMPK) pathway in the presence or absence of insulin. These results suggest that bavachin from Psoralea corylifolia might have therapeutic potential for type 2 diabetes by activating insulin signaling pathways.

Biomolecular Characterization of Putative Antidiabetic Herbal Extracts

Induction of GLUT4 translocation in the absence of insulin is considered a key concept to decrease elevated blood glucose levels in diabetics. Due to the lack of pharmaceuticals that specifically increase the uptake of glucose from the blood circuit, application of natural compounds might be an alternative strategy. However, the effects and mechanisms of action remain unknown for many of those substances. For this study we investigated extracts prepared from seven different plants, which have been reported to exhibit anti-diabetic effects, for their GLUT4 translocation inducing properties. Quantitation of GLUT4 translocation was determined by total internal reflection fluorescence (TIRF) microscopy in insulin sensitive CHO-K1 cells and adipocytes. Two extracts prepared from purslane (Portulaca oleracea) and tindora (Coccinia grandis) were found to induce GLUT4 translocation, accompanied by an increase of intracellular glucose concentrations. Our results indicate that the PI3K pathway is mainly responsible for the respective translocation process. Atomic force microscopy was used to prove complete plasma membrane insertion. Furthermore, this approach suggested a compound mediated distribution of GLUT4 molecules in the plasma membrane similar to insulin stimulated conditions. Utilizing a fluorescent actin marker, TIRF measurements indicated an impact of purslane and tindora on actin remodeling as observed in insulin treated cells. Finally, in-ovo experiments suggested a significant reduction of blood glucose levels under tindora and purslane treated conditions in a living organism. In conclusion, this study confirms the anti-diabetic properties of tindora and purslane, which stimulate GLUT4 translocation in an insulin-like manner.

PPARγ activation alters fatty acid composition in adipose triglyceride, in addition to proliferation of small adipocytes, in insulin resistant high-fat fed rats

It was reported that adipocyte size is potentially correlated in part to amount of long chain polyunsaturated fatty acids (PUFAs) and insulin resistance because several long chain PUFAs can be ligands of peroxisome proliferator-activated receptors (PPARs). In our previous study, marked reduction of PUFAs was observed in insulin-resistant high-fat fed rats, which may indicate that PUFAs are consumed to improve insulin resistance. Although PPARγ agonist, well known as an insulin sensitizer, proliferates small adipocytes, the effects of PPARγ agonist on FA composition in adipose tissue have not been clarified yet. In the present study, we administered pioglitazone, a PPARγ agonist, to high-fat fed rats, and measured their FA composition of triglyceride fraction in adipose tissue and adipocyte diameters in pioglitazone-treated (PIO) and non-treated (control) rats. Insulin sensitivity was obtained with hyperinsulinemic euglycemic clamp. Average adipocyte diameter in the PIO group were smaller than that in the control one without change in tissue weight. In monounsaturated FAs (MUFAs), 14:1n-5, 16:1n-7, and 18:1n-9 contents in the PIO group were lower than those, respectively, in the control group. In contrast, 22:6n-3, 20:3n-6, 20:4n-6, and 22:4n-6 contents in the PIO group were higher than those, respectively, in the control group. Insulin sensitivity was higher in the PIO group than in the control one. These findings suggest that PPARγ activation lowered MUFAs whereas suppressed most of C20 or C22 PUFAs reduction, and that the change of fatty acid composition may be relevant with increase in small adipocytes.

Classification of Therapeutic and Experimental Drugs for Brown Adipose Tissue Activation: Potential Treatment Strategies for Diabetes and Obesity

OBJECTIVE

Increasing efforts are being made towards pharmacologic activation of brown adipose tissue (BAT) in animals and humans for potential use in the treatment of obesity and diabetes. We and others have reported a number of animal studies using either experimental or therapeutic drugs. There are now efforts to translate these findings to human studies. The goal of this review is to evaluate the various drugs currently being used that have the potential for BAT activation.

METHODS

Drugs were classified into 4 classes based on their mechanism of action. Class 1 drugs include the use of β3 adrenoceptor agonists for BAT activation. Class 2 drugs include drugs that affect norepinephrine levels and activate BAT with the potential of reducing obesity. Class 3 includes activators of peroxisome proliferator-activated receptor-γ in pursuit of lowering blood sugar, weight loss and diabetes and finally Class 4 includes natural products and other emerging drugs with limited information on BAT activation and their effects on diabetes and weight loss.

RESULTS

Class 1 drugs are high BAT activators followed by Class 2 and 3. Some of these drugs have now been extended to diabetes and obesity animal models and human BAT studies. Drugs in Class 3 are used clinically for Type 2 diabetes, but the extent of BAT involvement is unclear.

CONCLUSION

Further studies on the efficacy of these drugs in diabetes and measuring their effects on BAT activation using noninvasive imaging will help in establishing a clinical role of BAT.

Isolation and Manipulation of Adipogenic Cells to Assess TGF-β Superfamily Functions

A variety of TGF-β superfamily members affect adipocyte differentiation and function with consequential effects on energy metabolism. There has been a growing interest in this area because of the apparent influence of the BMP subgroup on brown adipose characteristics and potential application to the treatment of human obesity. In this chapter we describe methods that are useful in allowing one to assess the roles of specific members of the superfamily on adipocyte differentiation and mature adipocyte function, including the isolation and differentiation of mouse embryo fibroblasts (MEFs) to examine cell autonomous effects and the efficient transfection of two commonly used (but difficult to transfect) adipogenic cell lines, C3H/10T1/2 and 3T3-L1.

Fish oil prevents excessive accumulation of subcutaneous fat caused by an adverse effect of pioglitazone treatment and positively changes adipocytes in KK mice

Pioglitazone, a thiazolidinedione (TZD), is widely used as an insulin sensitizer in the treatment of type 2 diabetes. However, body weight gain is frequently observed in TZD-treated patients. Fish oil improves lipid metabolism dysfunction and obesity. In this study, we demonstrated suppression of body weight gain in response to pioglitazone administration by combination therapy of pioglitazone and fish oil in type 2 diabetic KK mice. Male KK mice were fed experimental diets for 8 weeks. In safflower oil (SO), safflower oil/low-dose pioglitazone (S/PL), and safflower oil/high-dose pioglitazone (S/PH) diets, 20% of calories were provided by safflower oil containing 0%, 0.006%, or 0.012% (wt/wt) pioglitazone, respectively. In fish oil (FO), fish oil/low-dose pioglitazone (F/PL), and fish oil/high-dose pioglitazone (F/PH) diets, 20% of calories were provided by a mixture of fish oil and safflower oil. Increased body weight and subcutaneous fat mass were observed in the S/PL and S/PH groups; however, diets containing fish oil were found to ameliorate these changes. Hepatic mRNA levels of lipogenic enzymes were significantly decreased in fish oil-fed groups. These findings demonstrate that the combination of pioglitazone and fish oil decreases subcutaneous fat accumulation, ameliorating pioglitazone-induced body weight gain, through fish oil-mediated inhibition of hepatic de novo lipogenesis.

MicroRNA-223 is a crucial mediator of PPARγ-regulated alternative macrophage activation

Polarized activation of adipose tissue macrophages (ATMs) is crucial for maintaining adipose tissue function and mediating obesity-associated cardiovascular risk and metabolic abnormalities; however, the regulatory network of this key process is not well defined. Here, we identified a PPARγ/microRNA-223 (miR-223) regulatory axis that controls macrophage polarization by targeting distinct downstream genes to shift the cellular response to various stimuli. In BM-derived macrophages, PPARγ directly enhanced miR-223 expression upon exposure to Th2 stimuli. ChIP analysis, followed by enhancer reporter assays, revealed that this effect was mediated by PPARγ binding 3 PPARγ regulatory elements (PPREs) upstream of the pre-miR-223 coding region. Moreover, deletion of miR-223 impaired PPARγ-dependent macrophage alternative activation in cells cultured ex vivo and in mice fed a high-fat diet. We identified Rasa1 and Nfat5 as genuine miR-223 targets that are critical for PPARγ-dependent macrophage alternative activation, whereas the proinflammatory regulator Pknox1, which we reported previously, mediated miR-223-regulated macrophage classical activation. In summary, this study provides evidence to support the crucial role of a PPARγ/miR-223 regulatory axis in controlling macrophage polarization via distinct downstream target genes.

Lack of weight gain after angiotensin AT1 receptor blockade in diet-induced obesity is partly mediated by an angiotensin-(1-7)/Mas-dependent pathway

BACKGROUND AND PURPOSE

Angiotensin AT1 receptor antagonists induce weight loss; however, the mechanism underlying this phenomenon is unknown. The Mas receptor agonist angiotensin-(1-7) is a metabolite of angiotensin I and of angiotensin II . As an agonist of Mas receptors, angiotensin-(1-7) has beneficial cardiovascular and metabolic effects.

EXPERIMENTAL APPROACH

We investigated the anti-obesity effects of transgenically overexpressed angiotensin-(1-7) in rats. We secondly examined whether weight loss due to telmisartan (8 mg·kg(-1) ·d(-1) ) in diet-induced obese Sprague Dawley (SD) rats can be blocked when the animals were co-treated with the Mas receptor antagonist A779 (24 or 72 μg·kg(-1) ·d(-1) ).

KEY RESULTS

In contrast to wild-type controls, transgenic rats overexpressing angiotensin-(1-7) had 1.) diminished body weight when they were regularly fed with chow; 2.) were protected from developing obesity although they were fed with cafeteria diet (CD); 3.) showed a reduced energy intake that was mainly related to a lower CD intake; 5.) remained responsive to leptin despite chronic CD feeding; 6.) had a higher, strain-dependent energy expenditure, and 7.) were protected from developing insulin resistance despite CD feeding. Telmisartan-induced weight loss in SD rats was partially antagonized after a high, but not a low dose of A779.

CONCLUSIONS AND IMPLICATIONS

Angiotensin-(1-7) regulated food intake and body weight and contributed to the weight loss after AT1 receptor blockade. Angiotensin-(1-7)-like agonists may be drug candidates for treating obesity.

Umbelliferone Improves an Impaired Glucose and Lipid Metabolism in High-Fat Diet/Streptozotocin-Induced Type 2 Diabetic Rats

Umbelliferone (UMB) is a natural product that has several pharmacological effects including antihyperglycemic activity in diabetic rats. Thus, the objective of this study was to investigate the effect of UMB on insulin resistance and on the regulation of glucose and lipid metabolism in type 2 diabetic rats. Type 2 diabetes was induced in rats by feeding a high-fat diet (45 kcal% fat) and a single dose of streptozotocin injection. After 8 weeks of treatment, UMB significantly reduced the elevated blood glucose levels and insulin resistance and increased the liver glycogen and serum adiponectin. Moreover, the serum lipid and the storages of triglyceride and non-esterified fatty acid in liver tissue were reduced. From histological examination, the lipid droplets in liver tissue were clearly decreased, and the fat cell size in the fat tissue was smaller in diabetic rats treated with UMB. Interestingly, UMB increased fat cell adiponectin, plasma membrane glucose transporter 4 (GLUT4) and peroxisome proliferator-activated receptor gamma (PPARγ), and liver PPARα protein expressions. Our findings demonstrate that UMB improves glucose and lipid metabolism in type 2 diabetes by stimulating the insulin secretion and the related mechanisms via stimulating expression of adiponectin, GLUT4, PPARγ, and PPARα-protein expressions. Copyright © 2015 John Wiley & Sons, Ltd.

Transgenic ω-3 PUFA enrichment alters morphology and gene expression profile in adipose tissue of obese mice: Potential role for protectins

OBJECTIVE

Dietary administration of ω-3 polyunsaturated fatty acids (PUFA) is often associated with altered adipose tissue (AT) morphology and/or function in obese mice. Yet, it is unclear whether this is an indirect consequence of reduced weight gain or results from direct actions of ω-3 PUFA. Here we studied the AT of high fat (HF)-fed fat-1 transgenic mice that convert endogenous ω-6 to ω-3 PUFA while maintaining equivalent fat accretion as their wild-type (WT) counterparts.

MATERIALS AND METHODS

Adipocyte size profiling, Affymetrix microarray pathway analysis, qPCR and protectin identification and analysis were performed in epididymal AT from hemizygous fat-1(+/-) mice and their wild type littermates that had been fed a HF diet for 8weeks from 6weeks of age.

RESULTS

Despite equivalent fat pad mass, we found that epididymal AT from HF-fed transgenic animals possesses fewer large and very large but more mid-size adipocytes compared to WT mice. In order to better understand the underlying mechanisms contributing to the observed alteration in adipocyte size we performed an Affymetrix microarray. Pathway analysis of these data highlighted adipogenesis, cholesterol biosynthesis, insulin signaling, prostaglandin synthesis/regulation and small ligand GPCRs as points where differentially expressed genes were significantly overrepresented. Observed changes were confirmed for four candidate genes: Cnr1, Cnr2, Faah and Pparg by qPCR. Finally we demonstrated that protectin DX is present in AT and that protectin DX and protectin D1 promote comparable PPARγ transcriptional activity.

CONCLUSIONS

These data provide unprecedented evidence that ω-3 PUFA coordinately regulate AT gene expression programs in a manner that is independent of restriction of weight gain or fat accrual and highlight an important influence of ω-3 PUFA on adipogenesis. Furthermore we provide primary evidence suggesting that protectins likely contribute to these effects via their influence on PPARγ.

Labrador tea (Rhododendron groenlandicum) attenuates insulin resistance in a diet-induced obesity mouse model

PURPOSE

Using a diet-induced obesity (DIO) mouse model, we investigated the antidiabetic effect of Labrador tea [Rhododendron groenlandicum (Oeder) Kron and Judd], a beverage and medicinal tea used by the Cree Nations of northern Quebec.

METHODS

C57BL6 mice were divided into five groups and given standard chow (~4 % of lipids) or high-fat diet (~35 % of lipids) for 8 weeks until they became obese and insulin resistant. Treatment began by adding the plant extract at three doses (125, 250 and 500 mg/kg) to the high-fat diet for another 8 weeks. At the end of the study, insulin-sensitive tissues (liver, skeletal muscle, adipose tissue) were collected to investigate the plant's molecular mechanisms.

RESULTS

Labrador tea significantly reduced blood glucose (13 %), the response to an oral glucose tolerance test (18.2 %) and plasma insulin (65 %) while preventing hepatic steatosis (42 % reduction in hepatic triglyceride levels) in DIO mice. It stimulated insulin-dependent Akt pathway (55 %) and increased the expression of GLUT4 (53 %) in skeletal muscle. In the liver, Labrador tea stimulated the insulin-dependent Akt and the insulin-independent AMP-activated protein kinase pathways. The improvement in hepatic steatosis observed in DIO-treated mice was associated with a reduction in inflammation (through the IKK α/β) and a decrease in the hepatic content of SREBP-1 (39 %).

CONCLUSIONS

Labrador tea exerts potential antidiabetic action by improving insulin sensitivity and mitigating high-fat diet-induced obesity and hyperglycemia. They validate the safety and efficacy of this plant, a promising candidate for culturally relevant complementary treatment in Cree diabetics.

Licochalcone F alleviates glucose tolerance and chronic inflammation in diet-induced obese mice through Akt and p38 MAPK

BACKGROUND & AIMS

Licochalcone (lico) F is a novel synthetic retrochalcone. In this study, we investigated the anti-inflammatory effects of lico F in vitro, and its effects on obesity-induced chronic inflammation, glucose intolerance, and fatty liver in vivo.

METHODS

The inhibitory effects of lico F on TNFα-induced inflammation were investigated using NF-κB luciferase reporter assay and RT-PCR. Diet-induced obese mice were treated orally, once per day, with vehicle or lico F (10 mg/kg/day), for 3 weeks, and blood, liver, and adipose tissues were analyzed.

RESULTS

Lico F inhibited TNFα-induced NF-κB activation and mRNA expression of TNFα, COX-2, IL-6, IL-1β, and NOS2. In obese mice, lico F administration significantly alleviated glucose tolerance without changes in body weight gain and food intake. Lico F reduced adipocyte size and macrophage infiltration into white adipose tissue and improved hepatic lesions, by decreasing fat droplets and glycogen deposition. The mRNA expression levels of TNFα, MCP-1, and CD68 in white adipose tissue also decreased markedly. Moreover, lico F enhanced Akt signaling, but reduced p38 MAPK signaling in white adipose tissue.

CONCLUSIONS

Lico F had anti-inflammatory effects and showed beneficial effects on glucose metabolism, which could be partially caused by activation of the Akt signal pathway and obesity-induced chronic inflammation, probably by downregulating p38 signal pathway. Moreover, lico F could be used as a potential novel therapeutic compound against type 2 diabetes and obesity-induced chronic inflammation without the deleterious effects of body weight gain and fatty liver.

Evaluation of the synuclein-γ (SNCG) gene as a PPARγ target in murine adipocytes, dorsal root ganglia somatosensory neurons, and human adipose tissue

Recent evidence in adipocytes points to a role for synuclein-γ in metabolism and lipid droplet dynamics, but interestingly this factor is also robustly expressed in peripheral neurons. Specific regulation of the synuclein-γ gene (Sncg) by PPARγ requires further evaluation, especially in peripheral neurons, prompting us to test if Sncg is a bona fide PPARγ target in murine adipocytes and peripheral somatosensory neurons derived from the dorsal root ganglia (DRG). Sncg mRNA was decreased in 3T3-L1 adipocytes (~68%) by rosiglitazone, and this effect was diminished by the PPARγ antagonist T0070907. Chromatin immunoprecipitation experiments confirmed PPARγ protein binding at two promoter sequences of Sncg during 3T3-L1 adipogenesis. Rosiglitazone did not affect Sncg mRNA expression in murine cultured DRG neurons. In subcutaneous human WAT samples from two cohorts treated with pioglitazone (>11 wks), SNCG mRNA expression was reduced, albeit highly variable and most evident in type 2 diabetes. Leptin (Lep) expression, thought to be coordinately-regulated with Sncg based on correlations in human adipose tissue, was also reduced in 3T3-L1 adipocytes by rosiglitazone. However, Lep was unaffected by PPARγ antagonist, and the LXR agonist T0901317 significantly reduced Lep expression (~64%) while not impacting Sncg. The results support the concept that synuclein-γ shares some, but not all, gene regulators with leptin and is a PPARγ target in adipocytes but not DRG neurons. Regulation of synuclein-γ by cues such as PPARγ agonism in adipocytes is logical based on recent evidence for an important role for synuclein-γ in the maintenance and dynamics of adipocyte lipid droplets.

Antidiabetic plants used among the ethnic communities of Unakoti district of Tripura, India

ETHNOPHARMACOLOGICAL RELEVANCE

A large group of ethnic communities living in Unakoti district of Tripura, India is still dependent on traditional herbal remedies for treatment of diabetes. Valuable information collected from these communities in the present investigation is important in maintaining their indigenous knowledge of folklore medicine.

METHODS

Systematic and extensive field surveys were conducted during 2011-2013 among the ethnic inhabitants of Unokati district, Tripura, India covering all the seasons to collect information on their traditional herbal medication system for treatment of diabetes. Obtained data were analysed through fidelity level (FL), use value (UV) and relative frequency of citation (RFC) to authenticate the uniqueness of the species being used for diabetes treatment.

RESULTS

In this current study a total of 39 medicinal plant species belonging to 37 genera and 28 families were presented, used by the traditional healers of Unakoti district, Tripura, India for diabetes treatment. FL, UV and RFC values of collected plants for the selected study area ranges between 06% and 100%, 0.07% and 2.64% and 0.02% and 0.51% respectively. Out of 39 collected plants, 11, 5 and 3 plant species have showed significant (<50%) FL, UV and RFC values respectively.

CONCLUSION

Like many other ethnic communities of the world, inhabitants of Unakoti district depend on a traditional medication system to treat diabetes. Documented floras are locally available and need proper further pharmacological validation to endorse their traditional use in a modern health care system. This will help in the development of effective herbal antidiabetic medicines in near future.

The herbal composition GGEx18 from Laminaria japonica, Rheum palmatum, and Ephedra sinica inhibits visceral obesity and insulin resistance by upregulating visceral adipose genes involved in fatty acid oxidation

CONTEXT

The herbal composition Gyeongshingangjeehwan 18 (GGEx18) extracted from Rheum palmatum L. (Polygonaceae), Laminaria japonica Aresch (Laminariaceae), and Ephedra sinica Stapf (Ephedraceae) is traditionally used as an anti-obesity drug by local clinics in Korea.

OBJECTIVE

This study investigates the effects of GGEx18 on visceral obesity and insulin resistance and determines the molecular mechanisms involved in this process.

MATERIALS AND METHODS

After C57BL/6J mice were fed a high-fat diet supplemented with GGEx18 (125, 250, and 500 mg/kg) for 8 weeks and 3T3-L1 adipocytes were treated with GGEx18 (0.1, 1, and 10 μg/ml); variables and determinants of visceral obesity and insulin resistance were measured using in vivo and in vitro approaches.

RESULTS

Administration of GGEx18 to obese mice decreased visceral adipose tissue weight with an ED50 value of 232 mg/kg. 3T3-L1 adipocytes treated with GGEx18 showed a reduction in lipid accumulation with an ED50 value of 0.7 µg/ml. GGEx18 significantly increased the expression of fatty acid oxidation genes, including adiponectin, AMPKs, PPARα and its target enzymes, and CPT-1, in both mesenteric adipose tissues and 3T3-L1 cells. However, GGEx18 treatment decreased the mRNA levels of adipocyte marker genes such as PPARγ, aP2, TNFα, and leptin. GGEx18 normalized hyperglycemia and hyperinsulinemia in obese mice. Blood glucose levels of GGEx18-treated mice were significantly reduced during oral glucose tolerance tests compared with obese controls.

DISCUSSION AND CONCLUSION

These results suggest that GGEx18 may treat visceral obesity and visceral obesity-related insulin resistance by upregulating the visceral adipose expression of fatty acid oxidative genes.

Glycyrrhizic acid can attenuate metabolic deviations caused by a high-sucrose diet without causing water retention in male Sprague-Dawley rats

Glycyrrhizic acid (GA) ameliorates many components of the metabolic syndrome, but its potential therapeutic use is marred by edema caused by inhibition of renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). We assessed whether 100 mg/kg per day GA administered orally could promote metabolic benefits without causing edema in rats fed on a high-sucrose diet. Groups of eight male rats were fed on one of three diets for 28 days: normal diet, a high-sucrose diet, or a high-sucrose diet supplemented with GA. Rats were then culled and renal 11β-HSD2 activity, as well as serum sodium, potassium, angiotensin II and leptin levels were determined. Histological analyses were performed to assess changes in adipocyte size in visceral and subcutaneous depots, as well as hepatic and renal tissue morphology. This dosing paradigm of GA attenuated the increases in serum leptin levels and visceral, but not subcutaneous adipocyte size caused by the high-sucrose diet. Although GA decreased renal 11β-HSD2 activity, it did not affect serum electrolyte or angiotensin II levels, indicating no onset of edema. Furthermore, there were no apparent morphological changes in the liver or kidney, indicating no toxicity. In conclusion, it is possible to reap metabolic benefits of GA without edema using the current dosage and treatment time.

Immune and Inflammatory Signaling Pathways in Exercise and Obesity

Over the last decades the combination of both a sedentary lifestyle and excessive food availability has led to a significant increase in the prevalence of obesity, which is increasingly recognized as an important risk factor for type 2 diabetes. Several lines of evidence exist demonstrating that expanded visceral adipose tissue produces several pro-inflammatory mediators that activate signaling pathways that contribute to the development of insulin resistance. Exercise training is an important lifestyle factor that is widely used as a tool for preventing and improving lifestyle-related obesity and insulin resistance. In this regard, exercise training is useful to increase energy expenditure thereby counteracting a positive energy balance. Exercise training is also able to attenuate the activation of several obesity-induced pathways of inflammation and oxidative stress. Thus, a better understanding of the molecular mechanisms and immune pathways in exercise, obesity, and diabetes can be extremely useful to exploit optimized lifestyle strategies to combat the increasing incidence of metabolic diseases.

Ursolic acid increases glucose uptake through the PI3K signaling pathway in adipocytes

BACKGROUND

Ursolic acid (UA), a triterpenoid compound, is reported to have a glucose-lowering effect. However, the mechanisms are not fully understood. Adipose tissue is one of peripheral tissues that collectively control the circulating glucose levels.

OBJECTIVE

The objective of the present study was to determine the effect and further the mechanism of action of UA in adipocytes.

METHODS AND RESULTS

The 3T3-L1 preadipocytes were induced to differentiate and treated with different concentrations of UA. NBD-fluorescent glucose was used as the tracer to measure glucose uptake and Western blotting used to determine the expression and activity of proteins involved in glucose transport. It was found that 2.5, 5 and 10 µM of UA promoted glucose uptake in a dose-dependent manner (17%, 29% and 35%, respectively). 10 µM UA-induced glucose uptake with insulin stimulation was completely blocked by the phosphatidylinositol (PI) 3-kinase (PI3K) inhibitor wortmannin (1 µM), but not by SB203580 (10 µM), the inhibitor of mitogen-activated protein kinase (MAPK), or compound C (2.5 µM), the inhibitor of AMP-activated kinase (AMPK) inhibitor. Furthermore, the downstream protein activities of the PI3K pathway, phosphoinositide-dependent kinase (PDK) and phosphoinositide-dependent serine/threoninekinase (AKT) were increased by 10 µM of UA in the presence of insulin. Interestingly, the activity of AS160 and protein kinase C (PKC) and the expression of glucose transporter 4 (GLUT4) were stimulated by 10 µM of UA under either the basal or insulin-stimulated status. Moreover, the translocation of GLUT4 from cytoplasm to cell membrane was increased by UA but decreased when the PI3K inhibitor was applied.

CONCLUSIONS

Our results suggest that UA stimulates glucose uptake in 3T3-L1 adipocytes through the PI3K pathway, providing important information regarding the mechanism of action of UA for its anti-diabetic effect.

Amelioration of insulin resistance by rosiglitazone is associated with increased adipose cell size in obese type 2 diabetic patients

Early studies reported that the size of adipose cells positively correlates with insulin resistance, but recent evidence suggests that the relationship between adipose cell size and insulin resistance is more complex. We previously reported that among BMI-matched moderately obese subjects who were either insulin sensitive or resistant insulin resistance correlated with the proportion of small adipose cells, rather than the size of the large adipose cells, whereas the size of large adipose cells was found to be a predictor of insulin resistance in the first-degree relatives of type 2 diabetic (T2D) patients. The relationship between adipose cellularity and insulin resistance thus appears to depend on the metabolic state of the individual. We did a longitudinal study with T2D patients treated with the insulin-sensitizer rosiglitazone to test the hypothesis that improved insulin sensitivity is associated with increased adipocyte size. Eleven T2D patients were recruited and treated with rosiglitazone for 90 days. Blood samples and needle biopsies of abdominal subcutaneous fat were taken at six time points and analyzed for cell size distributions. Rosiglitazone treatment ameliorated insulin resistance as evidenced by significantly decreased fasting plasma glucose and increased index of insulin sensitivity, QUICKI. In association with this, we found significantly increased size of the large adipose cells and, with a weaker effect, increased proportion of small adipose cells. We conclude rosiglitazone treatment both enlarges existing large adipose cells and recruits new small adipose cells in T2D patients, improving fat storage capacity in adipose tissue and thus systemic insulin sensitivity.

Maintenance of white adipose tissue in man

Obesity is increasing in an epidemic manner in most countries and constitutes a public health problem by enhancing the risk for diseases such as diabetes, fatty liver disease and atherosclerosis. Together these diseases form a cluster referred to as the metabolic syndrome. Despite the negative health consequences associated with excess adipose tissue, very little is known about the origin and maintenance of white adipose tissue in man. In this review we discuss what is known about the turnover of adult human adipocytes and their precursors, as well as adipose tissue heterogeneity, plasticity and developmental origins. The focus of this review is human tissue, however in many cases human data are missing and are inferred from animal studies. As such, reference to animal studies are made where human data is not available. This article is part of a directed issue entitled: Regenerative Medicine: the challenge of translation.

Imaging of adipose tissue

Adipose tissue is an endocrine organ that specializes in lipid metabolism and is distributed throughout the body in distinct white adipose tissue (WAT) and brown adipose tissue (BAT) depots. These tissues have opposing roles in lipid metabolism with WAT storing excessive caloric intake in the form of lipid, and BAT burning lipid through nonshivering thermogenesis. As accumulation of lipid in mature adipocytes of WAT leads to obesity and increased risk of comorbidity (Pi-Sunyer et al., 1998), detailed understanding of the mechanisms of BAT activation and WAT accumulation could produce therapeutic strategies for combatting metabolic pathologies. As morphological changes accompany alterations in adipose function, imaging of adipose tissue is one of the most important tools for understanding how adipose tissue mass fluctuates in response to various physiological contexts. Therefore, this chapter details several methods of processing and imaging adipose tissue, including bright-field colorimetric imaging of paraffin-sectioned adipose tissue with a detailed protocol for automated adipocyte size analysis; fluorescent imaging of paraffin and frozen-sectioned adipose tissue; and confocal fluorescent microscopy of whole mounted adipose tissue. We have also provided many example images showing results produced using each protocol, as well as commentary on the strengths and limitations of each approach.

Effects of dietary thiazolidinedione supplementation on growth performance, intramuscular fat and related genes mRNA abundance in the longissimus dorsi muscle of finishing pigs

The objective of this study was to investigate the effect of dietary supplementation with thiazolidinedione (TZD) on growth performance and meat quality of finishing pigs. In Experiment 1, 80 castrated finishing pigs (Large White×Landrace, BW = 54.34 kg) were randomly assigned to 2 treatments with 5 replicates of 8 pigs each. The experimental pigs in the 2 groups were respectively fed with a diet with or without a TZD supplementation (15 mg/kg). In Experiment 2, 80 castrated finishing pigs (Large White×Landrace, BW = 71.46 kg) were divided into 2 treatments as designed in Experiment 1, moreover, carcass evaluations were performed. The results from Experiment 1 showed that TZD supplementation could significantly decreased the average daily feed intake (ADFI) (p<0.05) during 0 to 28 d, without impairing the average daily gain (ADG) (p>0.05). In Experiment 2, the ADG was significantly increased by TZD supplementation during 14 to 28 d and 0 to 28 d (p<0.05) and the feed:gain ratio (F:G) was significantly decreased by TZD supplementation during 0 to 28 d (p<0.05). Compared with the control group, TZD group had significantly higher serum triglyceride (TG) concentration at 28h and serum high-density lipoprotein (HDL) levels at 14 d (p<0.05). Moreover, there was an apparent improvement in the marbling score (p<0.10) and intramuscular fat (IMF) content (p<0.10) of the longissimus dorsi muscle in pigs treated by TZD supplementation. Real-time RT-PCR analyses demonstrated that pigs of TZD group had higher mRNA abundance of PPARγ coactivator 1 (PGC-1) (p<0.05) and fatty acid-binding protein 3 (FABP3) (p<0.05) than pigs of control group. Taken together, these results suggested that dietary TZD supplementation could improve growth performance and increase the IMF content of finishing pigs through regulating the serum parameters and genes mRNA abundance involved in fat metabolism.

The different shades of fat

Our understanding of adipose tissue biology has progressed rapidly since the turn of the century. White adipose tissue has emerged as a key determinant of healthy metabolism and metabolic dysfunction. This realization is paralleled only by the confirmation that adult humans have heat-dissipating brown adipose tissue, an important contributor to energy balance and a possible therapeutic target for the treatment of metabolic disease. We propose that the development of successful strategies to target brown and white adipose tissues will depend on investigations that elucidate their developmental origins and cell-type-specific functional regulators.

Positive interaction between prebiotics and thiazolidinedione treatment on adiposity in diet-induced obese mice

OBJECTIVES

To investigate whether inulin-type fructan (ITF) prebiotics could counteract the thiazolidinedione (TZD, PPARγ activator) induced-fat mass gain, without affecting its beneficial effect on glucose homeostasis, in high-fat (HF) diet fed mice.

METHODS

Male C57bl6/J mice were fed a HF diet alone or supplemented with ITF prebiotics (0.2 g/day × mouse) or TZD (30 mg pioglitazone (PIO)/kg body weight × day) or both during 4 weeks. An insulin tolerance test was performed after 3 weeks of treatment.

RESULTS

As expected, PIO improved glucose homeostasis and increased adiponectinaemia. Furthermore, it induced an over-expression of several PPARγ target genes in white adipose tissues. ITF prebiotics modulated the PIO-induced PPARγ activation in a tissue-dependent manner. The co-treatment with ITF prebiotics and PIO maintained the beneficial impact of TZD on glucose homeostasis and adiponectinaemia. Moreover, the combination of both treatments reduced fat mass accumulation, circulating lipids and hepatic triglyceride content, suggesting an overall improvement of metabolism. Finally, the co-treatment favored induction of white-to-brown fat conversion in subcutaneous adipose tissue, thereby leading to the development of brite adipocytes that could increase the oxidative capacity of the tissue.

CONCLUSIONS

ITF prebiotics decrease adiposity and improve the metabolic response in HF fed mice treated with TZD.

Expression profiling of PPARγ-regulated microRNAs in human subcutaneous and visceral adipogenesis in both genders

Clinical evidence shows that visceral fat accumulation decreases whereas sc fat increases in patients treated with thiazolidinediones (TZDs), a type of peroxisome proliferator-activated receptor (PPAR)γ agonist. To clarify the molecular mechanism of the differential effects of PPARγ agonists on sc and visceral adipose, we investigated expression profiling of PPARγ-regulated micro-RNAs (miRNAs) using miRNA microarray. The level of 182 miRNAs changed in human sc adipose treated with pioglitazone, whereas only 46 miRNAs changed in visceral adipose. Among these miRNAs, 27 miRNAs changed in both human sc and visceral adipocytes. Specifically, 7 miRNAs changed at the same direction in sc and visceral adipocytes, whereas 20 miRNAs changed at opposite directions in these two fat depots. Bioinformatics analysis showed that these miRNAs and the predicted target genes were involved in TGF-β-, Wnt/β-catenin-, and insulin-signaling pathways and related to metabolic regulation or cell cycle. Among the miRNAs changed at the same direction in sc and visceral adipocytes, miR-378, located in the first intron of PPARγ coactivator 1β (PGC1β), was coordinately expressed with PGC1β during adipogenesis. Moreover, miR-378 and PGC1β were both up-regulated by PPARγ agonist. We also provided evidence that miR-378 promoted adipogenesis in sc fat, but not in visceral fat. These results display miRNAs expression profiling altered in sc and visceral adipogenesis regulated by PPARγ and suggest a potential mechanism underlying the differential effects of TZDs on the 2 fat depot accumulations.

Ibervillea sonorae (Cucurbitaceae) induces the glucose uptake in human adipocytes by activating a PI3K-independent pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ibervillea sonorae (S. Watson) Greene (Cucurbitaceae), a plant used for the empirical treatment of type 2 diabetes in México, exerts antidiabetic effects on animal models but its mechanism of action remains unknown. The aim of this study is to investigate the antidiabetic mechanism of an Ibervillea sonorae aqueous extract (ISE).

MATERIALS AND METHODS

Non-toxic ISE concentrations were assayed on the glucose uptake by insulin-sensitive and insulin-resistant murine and human cultured adipocytes, both in the absence or the presence of insulin signaling pathway inhibitors, and on murine and human adipogenesis. Chemical composition of ISE was examined by spectrophotometric and HPLC techniques.

RESULTS

ISE stimulated the 2-NBDGlucose uptake by mature adipocytes in a concentration-dependent manner. ISE 50 µg/ml induced the 2-NBDG uptake in insulin-sensitive 3T3-F442A, 3T3-L1 and human adipocytes by 100%, 63% and 33%, compared to insulin control. Inhibitors for the insulin receptor, PI3K, AKT and GLUT4 blocked the 2-NBDG uptake in murine cells, but human adipocytes were insensitive to the PI3K inhibitor Wortmannin. ISE 50 µg/ml also stimulated the 2-NBDG uptake in insulin-resistant adipocytes by 117% (3T3-F442A), 83% (3T3-L1) and 48% (human). ISE induced 3T3-F442A adipogenesis but lacked proadipogenic effects on 3T3-L1 and human preadipocytes. Chemical analyses showed the presence of phenolics in ISE, mainly an appreciable concentration of gallic acid.

CONCLUSION

Ibervillea sonorae exerts its antidiabetic properties by means of hydrosoluble compounds stimulating the glucose uptake in human preadipocytes by a PI3K-independent pathway and without proadipogenic effects.