Glycine is a competitive antagonist of the TNF receptor mediating the expression of inflammatory cytokines in 3T3-L1 adipocytes.

OBJECTIVE: To determine the involvement of TNF-α and glycine receptors in the inhibition of pro-inflammatory adipokines in 3T3-L1 cells. METHODS: RT-PCR evidenced glycine receptors in 3T3-L1 adipocytes. 3T3-L1 cells were transfected with siRNA for the glycine (Glrb) and TNF1a (Tnfrsf1a) receptors and confirmed by confocal microscopy. Transfected cells were treated with glycine (10 mM). The expressions of TNF-α and IL-6 mRNA were measured by qRT-PCR, while concentrations were quantified by ELISA. RESULTS: Glycine decreased the expression and concentration of TNF-α and IL-6; this effect did not occur in the absence of TNF-α receptor due to siRNA. In contrast, glycine produced only slight changes in the expression of TNF-α and IL-6 in the absence of the glycine receptor due to siRNA. A docking analysis confirmed the possibility of binding glycine to the TNF-α1a receptor. CONCLUSION: These findings support the idea that glycine could partially inhibit the binding of TNF-α to its receptor and provide clues about the mechanisms by which glycine inhibits the secretion of pro-inflammatory adipokines in adipocytes through the TNF-α receptor.

α-Amyrin induces GLUT4 translocation mediated by AMPK and PPARδ/γ in C2C12 myoblasts.

α-Amyrin, a natural pentacyclic triterpene, has an antihyperglycemic effect in mice and dual PPARδ/γ action in 3T3-L1 adipocytes, and potential in the control of type 2 diabetes (T2D). About 80% of glucose uptake occurs in skeletal muscle cells, playing a significant role in insulin resistance (IR) and T2D. Peroxisome-proliferator activated receptors (PPARs), in particular PPARδ and PPARγ, are involved in the regulation of lipids and carbohydrates and, along with adenosine-monophosphate (AMP) - activated protein kinase (AMPK) and protein kinase B (Akt), are implicated in translocation of glucose transporter 4 (GLUT4); however, it is still unknown whether α-amyrin can affect these pathways in skeletal muscle cells. Our objective was to determine the action of α-amyrin in PPARδ, PPARγ, AMPK, and Akt in C2C12 myoblasts. The expression of PPARδ, PPARγ, fatty acid transporter protein (FATP), and GLUT4 was quantified using reverse transcription quantitative PCR and Western blot. α-Amyrin increased these markers along with phospho-AMPK (p-AMPK) but not p-Akt. Molecular docking showed that α-amyrin acts as an AMPK-allosteric activator, and may be related to GLUT4 translocation, as evidenced by confocal microscopy. These data support that α-amyrin could have an insulin-mimetic action in C2C12 myoblasts and should be considered as a bioactive molecule for new multitarget drugs with utility in T2D and other metabolic diseases.

Triterpenoids from Hibiscus sabdariffa L. with PPARδ/γ Dual Agonist Action: In Vivo, In Vitro and In Silico Studies.

Hibiscus sabdariffa is a medicinal plant consumed as a diuretic and anti-obesity remedy. Several pharmacological studies have shown its beneficial effects in metabolism. Peroxisome proliferator-activated receptors δ and γ may play a role in the actions of H. sabdariffa. These nuclear receptors regulate lipid and glucose metabolism and are therapeutic targets for type 2 diabetes. This research aimed to perform a phytochemical study guided by a bioassay from H. sabdariffa to identify compounds with peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ agonist activity, supported by messenger ribonucleic acid expression, molecular docking, lipid accumulation, and an antihyperglycemic effect. An oral glucose tolerance test in mice with the aqueous extract of H. sabdariffa and the dichloromethane extract of H. sabdariffa was performed. The dichloromethane extract of H. sabdariffa exhibited an antihyperglycemic effect. The dichloromethane extract of H. sabdariffa was fractioned, and four fractions were evaluated in 3T3-L1 adipocytes on peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 messenger ribonucleic acid expression. Fraction F3 exhibited peroxisome proliferator-activated receptor δ/γ dual agonist activity, and a further fractionation yielded two subfractions, F3-1 and F3-2, which also increased peroxisome proliferator-activated receptor δ and peroxisome proliferator-activated receptor γ expression. Subfractions were analyzed by GC/MS. The main compounds identified in F3-1 were linoleic acid, oleic acid, and palmitic acid, while in F3-2, the main compounds identified were α-amyrin and lupeol. These molecules were subjected to molecular docking analysis. α-Amyrin and lupeol showed the highest affinity. Moreover, both produced an increase in peroxisome proliferator-activated receptor δ, peroxisome proliferator-activated receptor γ, fatty acid transporter protein, and glucose transporter type 4 expression. Additionally, α-amyrin and lupeol decreased lipid accumulation in 3T3-L1 adipocytes and blood glucose in mice. Until now, α-amyrin and lupeol have not been reported with activity on peroxisome proliferator-activated receptors. This study provides evidence that α-amyrin and lupeol possess antidiabetic effects through a peroxisome proliferator-activated receptor δ/γ dual agonist action.

Fermented blueberry juice extract and its specific fractions have an anti-adipogenic effect in 3 T3-L1 cells.

BACKGROUND: Obesity and Type 2 diabetes have reached epidemic status worldwide. Wild lowbush blueberry (Vaccinium angustifolium Aiton) is a plant of the North American Aboriginal traditional pharmacopeia with antidiabetic potential, especially when it is fermented with Serratia vaccinii. METHODS: A phytochemical fractionation scheme was used to identify potential bioactive compounds as confirmed by HPLC retention times and UV-Vis spectra. 3 T3-L1 cells were differentiated for 7 days with either Normal Blueberry Extract (NBE), Fermented Blueberry Extract (FBE/F1), seven fractions and four pure compounds. Triglyceride content was measured. Examination of selected intracellular signalling components (p-Akt, p-AMPK) and transcriptional factors (SREBP-1c and PPARγ) was carried out by Western blot analysis. RESULTS: The inhibitory effect of FBE/F1 on adipocyte triglyceride accumulation was attributed to total phenolic (F2) and chlorogenic acid enriched (F3-2) fractions that both inhibited by 75%. Pure compounds catechol (CAT) and chlorogenic acid (CA) also inhibited adipogenesis by 70%. Treatment with NBE, F1, F3-2, CAT and CA decreased p-AKT, whereas p-AMPK tended to increase with F1. The expression of SREBP1-c was not significantly modulated. In contrast, PPARγ decreased in all experimental groups that inhibited adipogenesis. CONCLUSIONS: These results demonstrate that fermented blueberry extract contains compounds with anti-adipogenic activity, which can serve to standardize nutraceutical preparations from fermented blueberry juice and to develop novel compounds with anti-obesity properties.

Synthesis, in vitro and in silico studies of a PPARγ and GLUT-4 modulator with hypoglycemic effect.

Compound {4-[({4-[(Z)-(2,4-dioxo-1,3-thiazolidin-5-ylidene)methyl]phenoxy}acetyl)amino]phenoxy}acetic acid (1) was prepared and the in vitro relative expression of PPARγ, GLUT-4 and PPARα, was estimated. Compound 1 showed an increase of 2-fold in the mRNA expression of PPARγ isoform, as well as the GLUT-4 levels. The antidiabetic activity of compound 1 was determined at 50 mg/Kg single dose using a non insulin dependent diabetes mellitus (NIDDM) rat model. The in vivo results indicated a significant decrease of plasma glucose levels, during the 7 h post-administration. Also, we performed a molecular docking of compound 1 into the ligand binding pocket of PPARγ, showing important short contacts with residues Ser289, His323 and His449 in the active site.

Biochemical alterations during the obese-aging process in female and male monosodium glutamate (MSG)-treated mice.

Obesity, from children to the elderly, has increased in the world at an alarming rate over the past three decades, implying long-term detrimental consequences for individual's health. Obesity and aging are known to be risk factors for metabolic disorder development, insulin resistance and inflammation, but their relationship is not fully understood. Prevention and appropriate therapies for metabolic disorders and physical disabilities in older adults have become a major public health challenge. Hence, the aim of this study was to evaluate inflammation markers, biochemical parameters and glucose homeostasis during the obese-aging process, to understand the relationship between obesity and health span during the lifetime. In order to do this, the monosodium glutamate (MSG) obesity mice model was used, and data were evaluated at 4, 8, 12, 16 and 20 months in both female and male mice. Our results showed that obesity was a major factor contributing to premature alterations in MSG-treated mice metabolism; however, at older ages, obesity effects were attenuated and MSG-mice became more similar to normal mice. At a younger age (four months old), the Lee index, triglycerides, total cholesterol, TNF-α and transaminases levels increased; while adiponectin decreased and glucose tolerance and insulin sensitivity levels were remarkably altered. However, from 16 months old-on, the Lee index and TNF-α levels diminished significantly, while adiponectin increased, and glucose and insulin homeostasis was recovered. In summary, MSG-treated obese mice showed metabolic changes and differential susceptibility by gender throughout life and during the aging process. Understanding metabolic differences between genders during the lifespan will allow the discovery of specific preventive treatment strategies for chronic diseases and functional decline.

Bioassay-guided chemical study of the anti-inflammatory effect of Senna villosa (Miller) H.S. Irwin & Barneby (Leguminosae) in TPA-induced ear edema.

Senna villosa (Miller) is a plant that grows in México. In traditional Mexican medicine, it is used topically to treat skin infections, pustules and eruptions and to heal wounds by scar formation. However, studies of its potential anti-inflammatory effects have not been performed. The aim of the present study was to determine the anti-inflammatory effect of extracts from the leaves of Senna villosa and to perform a bioassay-guided chemical study of the extract with major activity in a model of ear edema induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). The results reveal that the chloroform extract from Senna villosa leaves has anti-inflammatory and anti-proliferative properties. Nine fractions were obtained from the bioassay-guided chemical study, including a white precipitate from fractions 2 and 3. Although none of the nine fractions presented anti-inflammatory activity, the white precipitate exhibited pharmacological activity. It was chemically characterized using mass spectrometry and infrared and nuclear magnetic resonance spectroscopy, resulting in a mixture of three aliphatic esters, which were identified as the principal constituents: hexyl tetradecanoate (C20H40O2), heptyl tetradecanoate (C21H42O2) and octyl tetradecanoate (C22H44O2). This research provides, for the first time, evidence of the anti-inflammatory and anti-proliferative properties of compounds isolated from Senna villosa.

Role of Perivascular Adipose Tissue in Aorta Reactivity from Obese and Hyperglycemic CD-1 Mice: New Insights into Perivascular Adipose Tissue.

Background: Perivascular adipose tissue (PVAT) plays an essential role in cardiovascular homeostasis. However, during obesity and diabetes, its role in vascular tone regulation is unclear. This study aimed to evaluate the function of the PVAT on aorta reactivity in the lean and cafeteria (CAF) diet-induced obese-hyperglycemic mice model. Methods: Aorta reactivity to phenylephrine, KCl, and acetylcholine was analyzed in lean (n = 6) and obese mice (n = 6). Also, nitric oxide (NO-) and cyclooxygenase participation, in the presence (n = 6) and absence (n = 6) of PVAT, were examined in the aortas. Results: After a CAF diet for 19 weeks, obese mice showed increased body weight, glucose intolerance, and hypercholesterolemia concerning lean mice. Vascular reactivity to phenylephrine was reduced significantly in the aorta of obese mice. In contrast, the contraction produced by KCl (80 mM) was increased in the aorta of obese mice independent of PVAT. Acetylcholine-induced vasorelaxation diminished in the aortas of obese mice in the presence of PVAT. Nonselective inhibition of cyclooxygenases likely shows that PVAT and endothelium release vasorelaxant prostanoids. Conclusions: The results suggest that PVAT modulates aorta reactivity by releasing NO-, decreasing the α1-adrenergic response to phenylephrine, and probably releasing vasorelaxant prostanoids. The data suggest that PVAT regulates the vascular smooth muscle and endothelial function in a CAF diet-induced obese-hyperglycemic mice model.

Hypoglycemic Activity of Aqueous Extracts from Catharanthus roseus.

Introduction. Catharanthus roseus (L.) is used in some countries to treat diabetes. The aim of this study was to evaluate the hypoglycemic activity of extracts from the flower, leaf, stem, and root in normal and alloxan-induced diabetic mice. Methods. Roots, leaves, flowers, and stems were separated to obtain organic and aqueous extracts. The blood glucose lowering activity of these extracts was determinate in healthy and alloxan-induced (75 mg/Kg) diabetic mice, after intraperitoneal administration (250 mg/Kg body weight). Blood samples were obtained and blood glucose levels were analyzed employing a glucometer. The data were statistically compared by ANOVA. The most active extract was fractioned. Phytochemical screen and chromatographic studies were also done. Results. The aqueous extracts from C. roseus reduced the blood glucose of both healthy and diabetic mice. The aqueous stem extract (250 mg/Kg) and its alkaloid-free fraction (300 mg/Kg) significantly (P < 0.05) reduced blood glucose in diabetic mice by 52.90 and 51.21%. Their hypoglycemic activity was comparable to tolbutamide (58.1%, P < 0.05). Conclusions. The best hypoglycemic activity was presented for the aqueous extracts and by alkaloid-free stem aqueous fraction. This fraction is formed by three polyphenols compounds.

[The role of innate immunity in obesity]. / El papel de la inmunidad innata en la obesidad.

Obesity in Mexico is alarmingly increasing in prevalence in adults and children, and it is a risk factor for the development of insulin resistance, as well as, of other metabolic alterations. The discovery of the expression of the Toll-like receptors (TLRs) in adipocytes, suggests an important role in innate immunity. In different models of obesity, there has been observed an increase of TLRs expression in the fat tissue, therefore TLRs could be involved in systemic inflammation in this disease, and in the development of insulin resistance. TLR activation is mediated by fatty acids and their expression is regulated by leptin, adiponectin and PPARs. Knowledge of the role of TLRs in inflammation and adipocyte differentiation and their regulation, then it is important to try to develop new therapeutic anti-inflammatory targets that contribute in the treatment of obesity.

Antihyperglycemic Effects of Salvia polystachya Cav. and Its Terpenoids: α-Glucosidase and SGLT1 Inhibitors.

The antihyperglycemic activity of ethanolic extract from Salvia polystachya (EESpS) and its products was evaluated using in vivo, ex vivo and in silico assays; additionally, an acute toxicity assay was evaluated. EESpS was classified as a nontoxic class 5 drug. EESpS, ethyl acetate fraction (EtOAcFr), secondary-6-fraction (SeFr6), ursolic acid (UA), and oleanolic acid (OA) reduced the hyperglycemia in DM2 mice. α-glucosidase inhibition was evaluated with oral sucrose and starch tolerance tests (OSuTT and OStTT), an intestinal sucrose hydrolysis (ISH) assay and molecular docking studies using acarbose as control. SGLT1 inhibition was evaluated with oral glucose and galactose tolerance tests (OGTT and OGaTT), an intestinal glucose absorption (IGA) assay and molecular docking studies using canagliflozin as the control. During the carbohydrate tolerance tests, all the treatments reduced the postprandial peak, similar to the control drugs. During the ISH, IC50 values of 739.9 and 726.3 µM for UA and OA, respectively, were calculated. During the IGA, IC50 values of 966.6 and 849.3 for UA, OA respectively, were calculated. Finally, during the molecular docking studies, UA and OA showed ∆G values of -6.41 and -5.48 kcal/mol-1, respectively, on α-glucosidase enzymes. During SGLT1, UA and OA showed ∆G values of -10.55 and -9.65, respectively.

Jatropha Neopauciflora Pax Latex Exhibits Wound-Healing Effect in Normal and Diabetic Mice.

Jatropha neopauciflora is an endemic species of Mexico. Its latex is used to treat wounds, scarring, oral infections, and loose teeth. To date, there are no studies that validate at a morphological level a wound-healing use in diabetes. The present research aimed to evaluate the wound-healing capacity of the latex of J. neopauciflora in the skin of healthy and streptozotocin-induced diabetic mice. Also, a chemical analysis of the latex through molecular exclusion chromatography and HPLC were performed. Male mice (Mus musculus) of 7-week-old CD1 strain were used. Groups of healthy and diabetic mice were formed. A longitudinal cut of 1 cm was performed on the depilated skin. All treatments were topically applied to the wound area twice a day for ten days. At the end of the experiments, the skin sections were obtained from the wound area and stained with Hematoxylin-Eosin. Then we counted the number of active fibroblasts in all the experimental groups. In normal mice, the latex accelerated the wound-healing process and decreased the number of active fibroblasts, similarly to Recoveron. In diabetic mice, the latex and Recoveron increased the number of active fibroblasts. In normal and diabetic mice, a thin and orderly epidermis was observed. Molecular exclusion chromatography exhibited 58 fractions, 14 of which were subjected to HPLC, to detect catechin, a flavonoid with antioxidant, antimicrobial, and anti-inflammatory properties. J. neopauciflora latex can be useful for wound treatment in patients with diabetes mellitus because it accelerates and promotes the wound-healing process.

GLUT4 translocation in C2C12 myoblasts and primary mouse hepatocytes by an antihyperglycemic flavone from Tillandsia usneoides.

BACKGROUND: Type 2 Diabetes (T2D) is characterized by deregulation in carbohydrate and lipid metabolism, with a very high mortality rate. Glucose Transporter type 4 (GLUT4) plays a crucial role in T2D and represents a therapeutic target of interest. Tillandsia usneoides (T. usneoides) is a plant used as a remedy for diabetes. T. usneoides decreased blood glucose in different experimental models. However, the involvement of GLUT4 in this effect has not yet been explored. PURPOSE: This study aimed to investigate whether any component in T. usneoides might participate in the effect on blood glucose through a bioassay-guided fractionation, testing its potential antihyperglycemic effect in mice, as well as its influence on GLUT4 translocation in C2C12 myoblasts and primary hepatocytes. METHODS: The aqueous extract and the Ethyl Acetate fraction (TU-AcOEt) of T. usneoides were evaluated in a hypoglycemic activity bioassay and in the glucose tolerance test in CD-1 mice. TU-AcOEt was fractionated, obtaining five fractions that were studied in an additional glucose tolerance test. C1F3 was fractioned again, and its fractions (C2F9-12, C2F22-25, and C2F38-44) were examined by HPLC. The C2F38-44 fraction was analyzed by Mass Spectrometry (MS) and subjected to additional fractionation. The fraction C3F6-9 was explored by Nuclear Magnetic Resonance (NMR), resulting in 5,7,4´-trihydroxy-3,6,3´,5´-tetramethoxyflavone (Flav1). Subsequently, a viability test was performed to evaluate the cytotoxic effect of Flav1 and fractions C2F9-12, C2F22-25. C2F38-44, and C3F30-41 in C2C12 myoblasts and primary mouse hepatocytes. Confocal microscopy was also performed to assess the effect of Flav1 and fractions on GLUT4 translocation. RESULTS: The TU-AcOEt fraction exhibited a hypoglycemic and antihyperglycemic effect in mice, and its fractionation resulted in five fractions, among which fraction C1F3 decreased blood glucose. MS and NMR analysis revealed the presence of Flav1. Finally, Flav1 significantly promoted the translocation of GLUT4 in C2C12 myoblasts and primary hepatocytes. CONCLUSION: To date, Flav1 has not been reported to have activity in GLUT4; this study provides evidence that T. usneoides is a plant with the potential to develop novel therapeutic agents for the control of T2D.

Oleanolic acid induces a dual agonist action on PPARγ/α and GLUT4 translocation: A pentacyclic triterpene for dyslipidemia and type 2 diabetes.

Type 2 diabetes (T2D) is a metabolic disease characterized by defects in glycemia regulation. This disease is associated with alterations in insulin action and lipid metabolism, generating hyperglycemia and dyslipidemias. Currently, it is necessary to develop new or known drugs that promote the sensitization of insulin action. Thus, activation of peroxisome proliferator-activated receptors (PPARs) is probably the key to doing this. PPARs participate in maintaining an energetic balance between storage and the expenditure of energy. The activation of PPARγ produces the storage of energy, mainly as glycogen and fat. Meanwhile, PPARα activation promotes lipid degradation. Oleanolic acid (OA), a pentacyclic triterpenoid of numerous edible and medicinal plants, decreases hyperglycemia and lipid accumulation. However, the effects on PPARs and their regulated genes are unknown. Our aim was to determine the effects of OA on PPAR γ/α expression and their regulated genes (adiponectin, type 4 glucose transporter, fatty acid transport protein, and long-chain acyl-CoA synthetase) in C2C12 myoblasts by RT-PCR, Western blot, GLUT-4 translocation, and lipid storage in 3T3-L1 adipocytes. In C2C12 myoblasts, OA increased the expression of mRNA in both PPARγ/α and their regulated genes; also, PPARγ, GLUT-4, and FATP-1 protein expression increased, as well as GLUT-4 translocation. In 3T3-L1, OA increased the expression of mRNA in both PPARγ/α and maintained lipid storage unchanged. In conclusion, OA exhibited a dual action on PPARγ/α, which might explain in part its antihyperglycemic effect. This compound represents an alternative for designing novel therapeutic strategies in the control of T2D.

Mechanism of the Hypoglycemic Activity and Hepatoprotective Effect of the Aqueous Extract of Cecropia obtusifolia Bertol.

In Central and South American traditional medicine, people use Cecropia obtusifolia Bertol (Cecropiaceae) for the treatment of diabetes mellitus. However, its hypoglycemic action mechanism at pancreatic and liver level has been poorly explored. The present research aimed to establish the influence of the aqueous extract of C. obtusifolia, standardized in its content of chlorogenic acid, on insulin secretion in RINm5F cells and over the liver carbohydrates and lipids metabolism, and to determine concomitantly its hepatoprotective effect on mice with streptozotocin-induced diabetes. In RINm5F cells, concentrations 5, 50, 100, and 200 µg/mL of aqueous extract of C. obtusifolia were used to determine [Ca2+]i and insulin secretion. In an acute study, the extract was administered at doses of 500 mg/kg. In another test (subacute), the extract was daily administrated to diabetic mice (200 mg/kg/day) for 30 days. Blood glucose levels and other biochemical parameters were determined, and a liver histological analysis was performed. In RINm5F cells, C. obtusifolia increased [Ca2+]i and insulin secretion, whereas in diabetic mice exhibited acute and subacute hypoglycemic effects. Daily administration of C. obtusifolia to diabetic mice also increased liver glycogen storage and glycogen synthase levels, without apparent changes in gluconeogenesis. Besides, it increased peroxisome proliferator-activated receptor-α (PPAR-α) and long-chain-fatty-acid-CoA ligase 1 (ACSL-1) expression and reduced triglycerides, transaminases (alanine aminotransferase and aspartate aminotransferase), and collagen fibers, modifying anti-inflammatory (adiponectin and interleukin-10) and inflammatory (tumor necrosis factor-α) cytokines in serum. Therefore, the hypoglycemic effect of C. obtusifolia implicates a dual action, promoting insulin secretion, liver glycogen accumulation, and hepatoprotection by decreasing collagen fibers and inflammatory markers, whereas it improves lipid metabolism, due in part to PPAR-α.

Ayahuasca: Uses, Phytochemical and Biological Activities.

Ayahuasca (caapi, yajé), is a psychoactive brew from the Amazon Basin region of South America traditionally considered a "master plant." It is prepared as a decoction from Banisteriopsis caapi and Psychotria viridis, which it is thought that it stimulates creative thinking and visual creativity. Native healers of the Orinoco and Amazon basins have used traditionally ayahuasca as a healing tool for multiple purposes, particularly to treat psychological disorders in the patients, with some beneficial effects experimentally and clinically validated. Recently, several syncretic religions, as the "União de Vegetal" (UDV) group in Brazil, have been spread around the world. The use of ayahuasca has been popularized by internet and smart-shops, bringing the psychoactive substance to new highs, emerging new "ayahuasqueros." Ayahuasca has alkaloids as ß-carbolines and dimethyltryptamines, which inhibit the monoamine oxidase and active the 5-HT2A (5-hydroxytryptamine) receptor, respectively, resulting in hallucinations in the users. Ayahuasca induces a psychedelic change in the anteroposterior coupling of the electrophysiological brain oscillations in humans. Traditional ayahuasca beverage is generating pharmacological, commercial and spiritual interest among the scientific community, government people, and different populations worldwide. The goal of this article is to report about the uses, chemistry and biological activities of ayahuasca.

Glycine increases mRNA adiponectin and diminishes pro-inflammatory adipokines expression in 3T3-L1 cells.

Obesity and type 2 diabetes course with chronic low-grade inflammation, where adiponectin is down-regulated and pro-inflammatory markers, like interleukin (IL)-6, tumor necrosis factor alpha (TNF-alpha), and C-reactive protein (CRP), are up-regulated. A treatment option to improve the micro- and macro-complications in type 2 diabetes is the use of glycine, which has been demonstrated previously to increase the expression of anti-inflammatory cytokine IL-10 in monocytes and down-regulate the expression of TNF-alpha in monocytes and Kupffer cells. Recently, our group demonstrated that glycine decreases the pro-inflammatory plasmatic cytokines in type 2 diabetes. The aim of this study was to test the effect of glycine on adipokines expression in 3T3-L1 cells. Cells were grown and differentiated in the presence of 10 mM glycine. After 2 days of confluence, cells were differentiated to adipocytes in the same medium supplemented with insulin, dexamethasone, and 3-isobutyl-1-methylxanthine. The RNA was extracted at days 0 and 8 of differentiation (fibroblasts and mature adipocyte phenotypes, respectively). The expression of PPAR-gamma (peroxisome proliferator-activated receptor-gamma), adiponectin, resistin, IL-6 and TNF-alpha were analyzed by real-time PCR. We demonstrated that when 3T3-L1 cells were treated with glycine, IL-6, resistin and TNF-alpha mRNA expression was decreased, but surprisingly adiponectin and PPAR-gamma were up-regulated. In all cases the values were statistically significant (P<0.05) between glycine treatment and controls. These results show that glycine improves the pro-inflammatory profile and up-regulates adiponectin gene expression. Therefore, glycine could be useful as a modulator of the pro-inflammatory state observed in obesity and type 2 diabetes.

[Leptin and its association with obesity and type 2 diabetes]. / Leptina y su relación con la obesidad y la diabetes mellitus tipo 2.

The number of patients with metabolic disorders, obesity, type 2 diabetes and hypertension is increasing worldwide. The increase in body weight as a consequence of genetic, environmental, and nutritional factors contributes to these disorders, playing a significant role in their disease course. In 1994 the obesity gene (ob) which encodes a protein named leptin, considered an important molecule in regulation of body weight, was described Body weight gain has been generally correlated with high plasma levels of leptin, generating a state of leptin-resistance. Because of its association with obesity, leptin has also been connected with type 2 diabetes and insulin-resistance, an essential characteristic of this disease. Leptin has also been linked with other disorders such as dyslipidaemia, and cardiovascular disease (conditions that together are known as metabolic syndrome), as well as cancer, psychological deficits, sexual dysfunction, etc. We describe some important biochemical and molecular aspects associated with the physiology of leptin, emphasizing the pathological consequences associated with obesity and diabetes.

A Phenolic Fraction from Catharanthus roseus L. Stems Decreases Glycemia and Stimulates Insulin Secretion.

Catharanthus roseus (L.) G. (C. roseus) is a medicinal plant used traditionally for diabetes mellitus control. Several compounds of an alkaloidal nature have been proposed as hypoglycemic principles. However, little attention has been paid to other compounds in this plant that could also participate in this hypoglycemic activity. This study aimed to analyze the hypoglycemic effect of a polyphenolic fraction from C. roseus, as well as its action on insulin secretion and expression in RINm5F cells. Methods. An alkaloid-free aqueous extract was obtained from C. roseus stems. The hypoglycemic effect of different doses of this extract was evaluated in normal and streptozotocin-induced diabetic mice. This extract was fractionated by bipartition, and the resultant fractions were assessed by their hypoglycemic effects. Subsequently, the fraction with the greater hypoglycemic activity was added to the RINm5F cells, and the expression and secretion of insulin were analyzed. The antioxidant activity was determined by the DPPH method and through chromatographic analysis of the most active fraction by HPLC, using an Econosphere C18 column. Results. The aqueous alkaloid-free extract of C. roseus stems significantly reduced blood glucose in normal and diabetic mice. The fractionation of this extract provided three fractions, one of which (a precipitate) showed significant reductions in glycemia at 6 h (48.1 and 64.5% in normal and diabetic mice, respectively). This precipitate contained phenolic compounds and saponins. Its chromatographic analysis showed that it is formed by several phenolic compounds; gallic acid (0.053%) and chlorogenic acid (0.216%) were identified and quantified. Conclusion. The phenolic fraction of C. roseus containing gallic acid and chlorogenic acid had a hypoglycemic effect that may be explained by an increase in insulin secretion.

Participation of the IKK-α/ß complex in the inhibition of the TNF-α/NF-κB pathway by glycine: Possible involvement of a membrane receptor specific to adipocytes.

Glycine modulates inflammatory processes mediated by macrophages and adipocytes through decreasing the secretion of TNF-α, IL-6, and leptin, while increasing adiponectin. These effects have been associated with the inactivation of NF-κB in response to TNF-α, across an increase of its inhibitor IκB-α in adipocytes. However, glycine upstream mainly influences the IκB kinase (IKK) complex, a multi-protein kinase complex considered a critical point in regulation of the NF-κB pathway; whether that is responsible for the TNF-α-induced phosphorylation of IkB has not been explored. Additionally, although previous studies have described glycine interactions with specific receptors (GlyR) in different immune system cell types, it is currently unknown whether adipocytes present GlyR. In this research, participation of the IKK-α/ß complex in the inhibition of the TNF-α/NF-κB pathway by glycine was evaluated and associated with the synthesis and secretion of inflammatory cytokines in 3T3-L1 adipocytes. Furthermore, we also explored GlyR expression, its localization on the plasmatic membrane, intracellular calcium concentrations [Ca2+]i and strychnine antagonist action over the GlyR in these cells. Glycine decreased the IKK-α/ß complex and the phosphorylation of NF-κB, diminishing the expression and secretion of IL-6 and TNF-α, but increasing that of adiponectin. GlyR expression and its fluorescence in the plasma membrane were increased in the presence of glycine. In addition, glycine decreased [Ca2+]i; whereas strychnine + glycine treatment inhibited the activation of NF-κB observed with glycine. In conclusion, the reduction of TNF-α and IL-6 and suppression of the TNF-α/NF-κB pathway by glycine may be explained in part by inhibition of the IKK-α/ß complex, with a possible participation of GlyR in 3T3-L1 adipocytes.