CNTF: a target therapeutic for obesity-related metabolic disease?

The role of gp130 receptor cytokines in the regulation of metabolic homeostasis

It is well known that obesity is responsible, at least in part, for the increased incidence of chronic diseases such as type 2 diabetes, cardiovascular disease and certain types of cancer. Despite public education programs emphasizing lifestyle modifications to arrest this global pandemic, it is now estimated that 10-15% of the world's population are overweight or obese. As a result, new therapeutic options for the treatment of obesity-related disorders are clearly warranted. Much of the benefit of physical activity has been attributed to several mechanisms including reduced adiposity, increased cardiorespiratory fitness, reduced circulating lipids and the maintenance of muscle mass. However, the observation that the gp130 receptor cytokine interleukin-6 (IL-6) was released from skeletal muscle during exercise to improve metabolic homeostasis altered our understanding of the health benefits of exercise and opened avenues for research into potential novel therapeutics to treat metabolic disease. One gp130 receptor cytokine in particular, ciliary neurotrophic factor (CNTF), a pluripotent neurocytokine, showed efficacy as a potential anti-obesogenic therapy. This review examines the potential of gp130 receptor ligands, with a focus on IL-6 and CNTF as therapeutic strategies to treat obesity-related disorders.

Action of Administered Ciliary Neurotrophic Factor on the Mouse Dorsal Vagal Complex

Ciliary neurotrophic factor (CNTF) induces weight loss in obese rodents and humans through activation of the hypothalamic Jak-STAT (Janus kinase-signal transducer and activator of transcription) signaling pathway. Here, we tested the hypothesis that CNTF also affects the brainstem centers involved in feeding and energy balance regulation. To this end, wild-type and leptin-deficient (ob/ob and db/db) obese mice were acutely treated with intraperitoneal recombinant CNTF. Coronal brainstem sections were processed for immunohistochemical detection of STAT3, STAT1, STAT5 phosphorylation and c-Fos. In wild-type mice, CNTF treatment for 45 min induced STAT3, STAT1, and STAT5 phosphorylation in neurons as well as glial cells of the area postrema; here, the majority of CNTF-responsive cells activated multiple STAT isoforms, and a significant proportion of CNTF-responsive glial cells bore the immaturity and plasticity markers nestin and vimentin. After 120 min CNTF treatment, c-Fos expression was intense in glial cells and weak in neurons of the area postrema, it was intense in several neurons of the rostral and caudal solitary tract nucleus (NTS), and weak in some cholinergic neurons of the dorsal motor nucleus of the vagus. In the ob/ob and db/db mice, Jak-STAT activation and c-Fos expression were similar to those induced in wild-type mouse brainstem. Treatment with CNTF (120 min, to induce c-Fos expression) and leptin (25 min, to induce STAT3 phosphorylation) demonstrated the co-localization of the two transcription factors in a small neuron population in the caudal NTS portion. Finally, weak immunohistochemical CNTF staining, detected in funiculus separans, and meningeal glial cells, matched the modest amount of CNTF found by RT-qPCR in micropunched area postrema tissue, which in contrast exhibited a very high amount of CNTF receptor. Collectively, the present findings show that the area postrema and the NTS exhibit high, distinctive responsiveness to circulating exogenous and, probably, endogenous CNTF.

The JAK/STAT pathway in obesity and diabetes

Diabetes mellitus are complex, multi-organ metabolic pathologies characterized by hyperglycemia. Emerging evidence shows that the highly conserved and potent JAK/STAT signaling pathway is required for normal homeostasis, and, when dysregulated, contributes to the development of obesity and diabetes. In this review, we analyze the role of JAK/STAT activation in the brain, liver, muscle, fat and pancreas, and how this affects the course of the disease. We also consider the therapeutic implications of targeting the JAK/STAT pathway in treatment of obesity and diabetes.

The neuroprotective agent CNTF decreases neuronal metabolites in the rat striatum: an in vivo multimodal magnetic resonance imaging study

Ciliary neurotrophic factor (CNTF) is neuroprotective against multiple pathologic conditions including metabolic impairment, but the mechanisms are still unclear. To delineate CNTF effects on brain energy homeostasis, we performed a multimodal imaging study, combining in vivo proton magnetic resonance spectroscopy, high-performance liquid chromatography analysis, and in situ glutamate imaging by chemical exchange saturation transfer. Unexpectedly, we found that CNTF expression through lentiviral gene transfer in the rat striatum significantly decreased the levels of neuronal metabolites (N-acetyl-aspartate, N-acetyl-aspartyl-glutamate, and glutamate). This preclinical study shows that CNTF remodels brain metabolism, and suggests that decreased levels of neuronal metabolites may occur in the absence of neuronal dysfunction.

Leptin resistance and diet-induced obesity: central and peripheral actions of leptin

Obesity is a chronic disease that represents one of the most serious global health burdens associated to an excess of body fat resulting from an imbalance between energy intake and expenditure, which is regulated by environmental and genetic interactions. The adipose-derived hormone leptin acts via a specific receptor in the brain to regulate energy balance and body weight, although this protein can also elicit a myriad of actions in peripheral tissues. Obese individuals, rather than be leptin deficient, have in most cases, high levels of circulating leptin. The failure of these high levels to control body weight suggests the presence of a resistance process to the hormone that could be partly responsible of disturbances on body weight regulation. Furthermore, leptin resistance can impair physiological peripheral functions of leptin such as lipid and carbohydrate metabolism and nutrient intestinal utilization. The present document summarizes those findings regarding leptin resistance development and the role of this hormone in the development and maintenance of an obese state. Thus, we focused on the effect of the impaired leptin action on adipose tissue, liver, skeletal muscle and intestinal function and the accompanying relationships with diet-induced obesity. The involvement of some inflammatory mediators implicated in the development of obesity and their roles in leptin resistance development are also discussed.

Codon optimization and factorial screening for enhanced soluble expression of human ciliary neurotrophic factor in Escherichia coli

BACKGROUND

Neurotrophic factors influence survival, differentiation, proliferation and death of neuronal cells within the central nervous system. Human ciliary neurotrophic factor (hCNTF) has neuroprotective properties and is also known to influence energy balance. Consequently, hCNTF has potential therapeutic applications in neurodegenerative, obesity and diabetes related disorders. Clinical and biological applications of hCNTF necessitate a recombinant expression system to produce large amounts of functional protein in soluble form. Earlier attempts to express hCNTF in Escherichia coli (E. coli) were limited by low amounts and the need to refold from inclusion bodies.

RESULTS

In this report, we describe a strategy to effectively identify constructs and conditions for soluble expression of hCNTF in E. coli. Small-scale expression screening with soluble fusion tags identified many conditions that yielded soluble expression. Codon optimized 6-His-hCNTF construct showed soluble expression in all the conditions tested. Large-scale culture of the 6-His-hCNTF construct yielded high (10 - 20 fold) soluble expression (8 - 9 fold) as compared to earlier published reports. Functional activity of recombinant 6-His-hCNTF produced was confirmed by its binding to hCNTF receptor (hCNTFRα) with an EC50 = 36 nM.

CONCLUSION

Our results highlight the combination of codon optimization and screening soluble fusion tags as a successful strategy for high yielding soluble expression of hCNTF in E. coli. Codon optimization of the hCNTF sequence seems to be sufficient for soluble expression of hCNTF. The combined approach of codon optimization and soluble fusion tag screen can be an effective strategy for soluble expression of pharmaceutical proteins in E. coli.

Decreased cardiotrophin-1 levels are associated with a lower risk of developing the metabolic syndrome in overweight/obese children after a weight loss program

OBJECTIVE

Cardiotrophin-1 (CT-1) shares some similarities with other cytokines, and participates in the control of energy metabolism. Higher circulating levels are observed in obese humans, but little information is gathered in weight loss (WL) programs. Therefore, we aimed to investigate the association of serum CT-1 levels with metabolic variables and the risk of developing metabolic syndrome (MetS) after a WL program in overweight/obese children.

SUBJECTS AND METHODS

Forty-four overweight/obese children (mean age 11.5 y; 50% males) undergoing a 10-week WL program were enrolled. Subjects were dichotomized at the median of Body Mass Index-Standard Deviation Score (BMI-SDS) change, as high and low responders after intervention.

RESULTS

CT-1 levels were significantly reduced (-48 fmol/mL, p=0.043) in the high responder group after the WL program. They had significantly lower body weight (-3.7 kg, p<0.001), body fat mass (-8%, p<0.001), BMI-SDS (-0.78, p<0.001) and waist circumference (-5.4 cm, p<0.001), and a significant improvement in lipid and glucose profiles (p<0.05). Interestingly, decreased CT-1 levels significantly predicted changes in total cholesterol (41%) and LDL-cholesterol (28%). Moreover, in our participants the lower the CT-1 levels, the higher the reduction in MetS risk components, after the 10-week intervention, (p-ANCOVA=0.040, p-trend=0.024).

CONCLUSION

We showed, for the first time, a reduction in serum CT-1 levels after a WL program and this decrease in CT-1 was strongly associated with a reduction in cholesterol levels and in MetS risk factors in overweight/obese children. Our findings may suggest that CT-1 could be an indirect marker for the diagnosis of MetS in this population.

Molecular pathways linking metabolic inflammation and thermogenesis

Obesity is caused by chronic positive energy balance because of higher energy intake relative to energy expenditure. Thermogenesis, the capacity of an organism to produce heat, is an important component of energy expenditure. Thus targeting the molecular mechanisms controlling thermogenesis could be an effective strategy for the prevention or treatment of obesity. Thermogenesis is modulated by three major factors: environmental temperature, nutrient quantity and quality, and by systemic inflammation. Obesity is now recognized to be a state of chronic low-grade systemic inflammation, which has been proposed to play a major role in the pathogenesis of obesity and obesity-associated diseases. This review discussed the molecular pathways that are recruited during metabolic inflammation and that are also implicated in the control of thermogenesis and energy balance. It emerges that the complex signalling network recruited during metabolic inflammation exerts a balanced action on the modulation of thermogenesis and energy balance, with some pathways promoting weight gain whereas other pathways have opposite actions. It is thus concluded that immunomodulation of metabolic inflammation, rather than an anti-inflammatory intervention aiming at its suppression, may be a more promising strategy to increase thermogenesis for the treatment or prevention of obesity and its associated diseases.

Ciliary neurotrophic factor protects mice against streptozotocin-induced type 1 diabetes through SOCS3: the role of STAT1/STAT3 ratio in β-cell death

Type 1 diabetes is characterized by a loss of islet β-cells. Ciliary neurotrophic factor (CNTF) protects pancreatic islets against cytokine-induced apoptosis. For this reason, we assessed whether CNTF protects mice against streptozotocin-induced diabetes (a model of type 1 diabetes) and the mechanism for this protection. WT and SOCS3 knockdown C57BL6 mice were treated for 5 days with citrate buffer or 0.1 mg/kg CNTF before receiving 80 mg/kg streptozotocin. Glycemia in non-fasted mice was measured weekly from days 0-28 after streptozotocin administration. Diabetes was defined as a blood glucose > 11.2 mmol/liter. Wild-type (WT) and SOCS3 knockdown MIN6 cells were cultured with CNTF, IL1β, or both. CNTF reduced diabetes incidence and islet apoptosis in WT but not in SOCS3kd mice. Likewise, CNTF inhibited apoptosis in WT but not in SOCS3kd MIN6 cells. CNTF increased STAT3 phosphorylation in WT and SOCS3kd mice and MIN6 cells but reduced STAT1 phosphorylation only in WT mice, in contrast to streptozotocin and IL1β. Moreover, CNTF reduced NFκB activation and required down-regulation of inducible NO synthase expression to exert its protective effects. In conclusion, CNTF protects mice against streptozotocin-induced diabetes by increasing pancreatic islet survival, and this protection depends on SOCS3. In addition, SOCS3 expression and β-cell fate are dependent on STAT1/STAT3 ratio.

Green tea polyphenols reduce body weight in rats by modulating obesity-related genes

Beneficial effects of green tea polyphenols (GTP) against obesity have been reported, however, the mechanism of this protection is not clear. Therefore, the objective of this study was to identify GTP-targeted genes in obesity using the high-fat-diet-induced obese rat model. A total of three groups (n = 12/group) of Sprague Dawley (SD) female rats were tested, including the control group (rats fed with low-fat diet), the HF group (rats fed with high-fat diet), and the HF+GTP group (rats fed with high-fat diet and GTP in drinking water). The HF group increased body weight as compared to the control group. Supplementation of GTP in the drinking water in the HF+GTP group reduced body weight as compared to the HF group. RNA from liver samples was extracted for gene expression analysis. A total of eighty-four genes related to obesity were analyzed using PCR array. Compared to the rats in the control group, the rats in the HF group had the expression levels of 12 genes with significant changes, including 3 orexigenic genes (Agrp, Ghrl, and Nr3c1); 7 anorectic genes (Apoa4, Cntf, Ghr, IL-1β, Ins1, Lepr, and Sort); and 2 genes that relate to energy expenditure (Adcyap1r1 and Adrb1). Intriguingly, the HF+GTP group restored the expression levels of these genes in the high-fat-induced obese rats. The protein expression levels of IL-1β and IL-6 in the serum samples from the control, HF, and HF+GTP groups confirmed the results of gene expression. Furthermore, the protein expression levels of superoxide dismutase-1 (SOD1) and catechol-O-methyltransferase (COMT) also showed GTP-regulated protective changes in this obese rat model. Collectively, this study revealed the beneficial effects of GTP on body weight via regulating obesity-related genes, anti-inflammation, anti-oxidant capacity, and estrogen-related actions in high-fat-induced obese rats.

Role of neurotrophins in the development and function of neural circuits that regulate energy homeostasis

Members of the neurotrophin family, including nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-4/5, and other neurotrophic growth factors such as ciliary neurotrophic factor and artemin, regulate peripheral and central nervous system development and function. A subset of the neurotrophin-dependent pathways in the hypothalamus, brainstem, and spinal cord, and those that project via the sympathetic nervous system to peripheral metabolic tissues including brown and white adipose tissue, muscle and liver, regulate feeding, energy storage, and energy expenditure. We briefly review the role that neurotrophic growth factors play in energy balance, as regulators of neuronal survival and differentiation, neurogenesis, and circuit formation and function, and as inducers of critical gene products that control energy homeostasis.

Ciliary neurotrophic factor (CNTF) protects non-obese Swiss mice against type 2 diabetes by increasing beta cell mass and reducing insulin clearance

AIMS/HYPOTHESIS

Ciliary neurotrophic factor (CNTF) improves metabolic variables of obese animals with characteristics of type 2 diabetes, mainly by reducing insulin resistance. We evaluated whether CNTF was able to improve other metabolic variables in mouse models of type 2 diabetes, such as beta cell mass and insulin clearance, and whether CNTF has any effect on non-obese mice with characteristics of type 2 diabetes.

METHODS

Neonatal mice were treated with 0.1 mg/kg CNTF or citrate buffer via intraperitoneal injections, before injection of 250 mg/kg alloxan. HEPG2 cells were cultured for 3 days in the presence of citrate buffer, 1 nmol/l CNTF or 50 mmol/l alloxan or a combination of CNTF and alloxan. Twenty-one days after treatment, we determined body weight, epididymal fat weight, blood glucose, plasma insulin, NEFA, glucose tolerance, insulin resistance, insulin clearance and beta cell mass. Finally, we assessed insulin receptor and protein kinase B phosphorylation in peripheral organs, as well as insulin-degrading enzyme (IDE) protein production and alternative splicing in the liver and HEPG2 cells.

RESULTS

CNTF improved insulin sensitivity and beta cell mass, while reducing glucose-stimulated insulin secretion and insulin clearance in Swiss mice, improving glucose handling in a non-obese type 2 diabetes model. This effect was associated with lower IDE production and activity in liver cells. All these effects were observed even at 21 days after CNTF treatment.

CONCLUSIONS/INTERPRETATION

CNTF protection against type 2 diabetes is partially independent of the anti-obesity actions of CNTF, requiring a reduction in insulin clearance and increased beta cell mass, besides increased insulin sensitivity. Furthermore, knowledge of the long-term effects of CNTF expands its pharmacological relevance.

Targeting mTOR as a novel therapeutic strategy for traumatic CNS injuries

The adult central nervous system (CNS) has a remarkable ability to repair itself. However, severe brain and spinal cord injuries (SCIs) cause lasting disability and there are only a few therapies that can prevent or restore function in such cases. In this review, we provide an overview of traumatic CNS injuries and discuss several emerging pharmacological options that have shown promise in preclinical and early clinical studies. We highlight therapies that modulate mammalian target of rapamycin (mTOR) signaling, a pathway that is well known for its roles in cell growth, metabolism and cancer. Interestingly, this pathway is also gaining newfound attention for its role in CNS repair and regeneration.

Restoration of glucose metabolism in leptin-resistant mouse hearts after acute myocardial infarction through the activation of survival kinase pathways

In the normal heart, leptin modulates cardiac metabolism. It is unknown, however, what effect leptin has on cardiac metabolism and outcomes in acute myocardial infarction (MI). This study was performed to test the hypothesis that leptin signaling increases glucose metabolism and attenuates injury in the acutely infarcted heart. Mice with (ObR(+/+)) and without (ObR(-/-)) cardiomyocyte specific expression of leptin receptor (ObR) were randomly assigned to experimental MI or sham procedure, and studied 3 days later. ObR(+/+) and ObR(-/-) sham mice were not significantly different in any measured outcome. However, after MI, ObR(-/-) mice had greater cardiac dysfunction, left ventricular dilation, and levels of oxidative stress. These worse indices of cardiac injury in ObR(-/-) mice were associated with attenuated signal transducer and activator of transcription (STAT) 3, phosphatidylinositol-3-kinase (PI3K), and Akt signaling, decreased malonyl CoA content, and reduced mitochondrial pyruvate dehydrogenase and electron transport Complex I, II and IV activities. Furthermore, ObR(-/-) mice maintained high rates of cardiac fatty acid oxidation after MI, whereas ObR(+/+) mice demonstrated a switch away from fatty acid oxidation to glucose metabolism. Restoration of cardiac STAT3, PI3K and Akt activity and mitochondrial function in ObR(-/-) mice post-MI was accomplished by ciliary neurotrophic factor (CNTF), an established STAT3 activator, administered immediately after MI. Moreover, CNTF therapy resulted in mitigation of cardiac structural and functional injury, attenuated levels of oxidative stress, and rescued glucose metabolism in the infarcted ObR(-/-) heart. These data demonstrate that impaired cardiac leptin signaling results in metabolic inflexibility for glucose utilization in the face of cardiac stress, and greater morbidity after MI. Further, these studies show that cardiac glucose metabolism can be restored in leptin-resistant hearts by CNTF-mediated activation of survival kinases, resulting in multiple improved structural and functional outcomes post-MI.

The pharmacological treatment of obesity: Past, present and future

Currently, obesity presents one of the biggest health problems. Management strategies for weight reduction in obese individuals include changes in life style such as exercise and diet, behavioral therapy, and pharmacological treatment, and in certain cases surgical intervention. Diet and exercise are best for both prevention and treatment, but both require much discipline and are difficult to maintain. Drug treatment of obesity offer a possible adjunct, but it may only have modest results, limited by side effects; furthermore, the weight lowering effects last only as long as the drug is being taken and, unfortunately, as soon as the administration is stopped, the weight is regained. These strategies should be used in a combination for higher efficacy. Drugs used to induce weight loss have various effects: they increase satiety, reduce the absorption of nutrients or make metabolism faster; but their effect is usually moderate. In the past, several drugs were used in the pharmacological therapy of weight reduction including thyroid hormone, dinitrophenol, amphetamines and their analogues, e.g. fenfluramine, At present, only orlistat is available in the long term treatment (≥24 weeks) of obesity as sibutramine and rimonabant were withdrawn form the market. Several new anti-obesity drugs are being tested at present, and liraglutide, a GLP-1 analogue (incretin mimetic), is the most promising one. Orv. Hetil., 2012, 153, 363–373.

Vascular effects of glycoprotein130 ligands--part II: biomarkers and therapeutic targets

Glycoprotein130 (gp130) ligands are defined by the use of the common receptor subunit gp130 and comprise interleukin (IL)-6, oncostatin M (OSM), IL-11, leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), ciliary neurotrophic factor (CNTF), IL-27 and neuropoietin (NP). In part I of this review we addressed the pathophysiological functions of gp130 ligands with respect to the vascular wall. In part II of this review on the vascular effects of gp130 ligands we will discuss data about possible use of these molecules as biomarkers to predict development or progression of cardiovascular diseases. Furthermore, the possibility to modulate circulating levels of gp130 ligands or their tissue expression by specific antibodies, soluble gp130 protein, renin-angiotensin-aldosterone system (RASS) inhibitors, statins, agonists of peroxisome proliferator-activated receptors (PPAR), hormone replacement therapy, nonsteroidal anti-inflammatory drugs (NSAID) or lifestyle modulating strategies are presented. Recent knowledge about the application of recombinant cytokines from the gp130 cytokine family as therapeutic agents in obesity or atherosclerosis is also summarized. Thus the purpose of this review is to cover a possible usefulness of gp130 ligands as biomarkers and targets for therapy in cardiovascular pathologies.

CNTF and retina

Ciliary neurotrophic factor (CNTF) is one of the most studied neurotrophic factors for neuroprotection of the retina. A large body of evidence demonstrates that CNTF promotes rod photoreceptor survival in almost all animal models. Recent studies indicate that CNTF also promotes cone photoreceptor survival and cone outer segment regeneration in the degenerating retina and improves cone function in dogs with congenital achromotopsia. In addition, CNTF is a neuroprotective factor and an axogenesis factor for retinal ganglion cells (RGCs). This review focuses on the effects of exogenous CNTF on photoreceptors and RGCs in the mammalian retina and the potential clinical application of CNTF for retinal degenerative diseases.

A peptide derived from the CD loop-D helix region of ciliary neurotrophic factor (CNTF) induces neuronal differentiation and survival by binding to the leukemia inhibitory factor (LIF) receptor and common cytokine receptor chain gp130

Ciliary neurotrophic factor (CNTF) induces neuronal differentiation and promotes the survival of various neuronal cell types by binding to a receptor complex formed by CNTF receptor α (CNTFRα), gp130, and the leukemia inhibitory factor (LIF) receptor (LIFR). The CD loop-D helix region of CNTF has been suggested to be important for the cytokine interaction with LIFR. We designed a peptide, termed cintrofin, that encompasses this region. Surface plasmon resonance analysis demonstrated that cintrofin bound to LIFR and gp130, but not to CNTFRα, with apparent KD values of 35 nM and 1.1 nM, respectively. Cintrofin promoted the survival of cerebellar granule neurons (CGNs), in which cell death was induced either by potassium withdrawal or H2O2 treatment. Cintrofin induced neurite outgrowth from CGNs, and this effect was inhibited by specific antibodies against both gp130 and LIFR, indicating that these receptors are involved in the effects of cintrofin. The C-terminal part of the peptide, corresponding to the D helix region of CNTF, was shown to be essential for the neuritogenic action of the peptide. CNTF and LIF induced neurite outgrowth in CGNs plated on laminin-coated slides. On uncoated slides, CNTF and LIF had no neuritogenic effect but were able to inhibit cintrofin-induced neuronal differentiation, indicating that cintrofin and cytokines compete for the same receptors. In addition, cintrofin induced the phosphorylation of STAT3, Akt, and ERK, indicating that it exerts cell signaling properties similar to those induced by CNTF and may be a valuable survival agent with possible therapeutic potential.

Pharmacotherapy for obese adolescents

The pharmaceutical search to induce weight loss was precipitated by the United States Food and Drug Administration's (FDA) 1959 formal approval of phentermine for short-term weight loss despite limited research supporting its assertions of weight loss. In addition to sympathomimetic amine products like phentermine, other medications considered in this article include herbal products, sibutramine, orlistat, metformin, and rimonabant. The use of pharmacotherapy for morbidly obese adolescents should be part of a comprehensive weight-loss program that recommends diet, exercise, and behavioral modification. Side effects and the possibility of major adverse effects should be remembered when considering use of these products.

Thermogenesis and related metabolic targets in anti-diabetic therapy

Exercise, together with a low-energy diet, is the first-line treatment for type 2 diabetes type 2 diabetes . Exercise improves insulin sensitivity insulin sensitivity by increasing the number or function of muscle mitochondria mitochondria and the capacity for aerobic metabolism, all of which are low in many insulin-resistant subjects. Cannabinoid 1-receptor antagonists and β-adrenoceptor agonists improve insulin sensitivity in humans and promote fat oxidation in rodents independently of reduced food intake. Current drugs for the treatment of diabetes are not, however, noted for their ability to increase fat oxidation, although the thiazolidinediones increase the capacity for fat oxidation in skeletal muscle, whilst paradoxically increasing weight gain.There are a number of targets for anti-diabetic drugs that may improve insulin sensitivity insulin sensitivity by increasing the capacity for fat oxidation. Their mechanisms of action are linked, notably through AMP-activated protein kinase, adiponectin, and the sympathetic nervous system. If ligands for these targets have obvious acute thermogenic activity, it is often because they increase sympathetic activity. This promotes fuel mobilisation, as well as fuel oxidation. When thermogenesis thermogenesis is not obvious, researchers often argue that it has occurred by using the inappropriate device of treating animals for days or weeks until there is weight (mainly fat) loss and then expressing energy expenditure energy expenditure relative to body weight. In reality, thermogenesis may have occurred, but it is too small to detect, and this device distracts us from really appreciating why insulin sensitivity has improved. This is that by increasing fatty acid oxidation fatty acid oxidation more than fatty acid supply, drugs lower the concentrations of fatty acid metabolites that cause insulin resistance. Insulin sensitivity improves long before any anti-obesity effect can be detected.

Role of the neurotrophin network in eating disorders' subphenotypes: body mass index and age at onset of the disease

Eating disorders (ED) are severe psychiatric diseases that most likely result from, and are sustained by socio-cultural, psychological and biological factors. We explored whether members of the neurotrophin family are disease-modifying factors of quantitative traits, potentially contributing to the outcome or prognosis of the disease. We studied lifetime minimum and maximum body mass index (minBMI and maxBMI) and age at onset of the disease in a sample of 991 ED patients from France, Germany, Italy and Spain and analysed 183 genetic variants located in 10 candidate genes encoding different neurotrophins and their receptors. We used a hierarchical model approach to include prior genetic knowledge of the specific and found that variants in CNTF, in its receptor CNTFR, and in NTRK2 were significantly associated with a lower age at onset of the ED. In addition, one variant in NTRK1 was associated with a higher minBMI. The results suggest that for these two subphenotypes, CNTF, CNTFR, NTRK1 and NTRK2 might act as disease-modifying factors and add preliminary evidence to the global hypothesis that EDs are the result of complex interactions and reciprocal controls between the immune, endocrine and central nervous systems.

Approved and Off-Label Uses of Obesity Medications, and Potential New Pharmacologic Treatment Options

Available anti-obesity pharmacotherapy options remain very limited and development of more effective drugs has become a priority. The potential strategies to achieve weight loss are to reduce energy intake by stimulating anorexigenic signals or by blocking orexigenic signals, and to increase energy expenditure. This review will focus on approved obesity medications, as well as potential new pharmacologic treatment options.