Obesity: an epidemic in need of therapeutics

High sucrose consumption decouples intrinsic and synaptic excitability of AgRP neurons without altering body weight

BACKGROUND/OBJECTIVE

As the obesity epidemic continues, the understanding of macronutrient influence on central nervous system function is critical for understanding diet-induced obesity and potential therapeutics, particularly in light of the increased sugar content in processed foods. Previous research showed mixed effects of sucrose feeding on body weight gain but has yet to reveal insight into the impact of sucrose on hypothalamic functioning. Here, we explore the impact of liquid sucrose feeding for 12 weeks on body weight, body composition, caloric intake, and hypothalamic AgRP neuronal function and synaptic plasticity.

METHODS

Patch-clamp electrophysiology of hypothalamic AgRP neurons, metabolic phenotyping and food intake were performed on C57BL/6J mice.

RESULTS

While mice given sugar-sweetened water do not gain significant weight, they do show subtle differences in body composition and caloric intake. When given sugar-sweetened water, mice show similar alterations to AgRP neuronal excitability as in high-fat diet obese models. Increased sugar consumption also primes mice for increased caloric intake and weight gain when given access to a HFD.

CONCLUSIONS

Our results show that elevated sucrose consumption increased activity of AgRP neurons and altered synaptic excitability. This may contribute to obesity in mice and humans with access to more palatable (HFD) diets.

Hydro alcoholic green tea extract effect on high fat diet treated NMRI mice and 3T3L1 cells

Purpose

In order to counteract the obesity has epidemics, since current anti-obesity drugs effects remain limited, there is a need to provide new options. As a project aiming to assess potential anti obesity natural compounds, the effects of consumption of a minimal dose of green tea hydro alcoholic extract (GT) on adipocyte differentiation of 3T3L1 cell line were investigated.

Methods

Obesity was induced in female NMRI mice (which are less used overall) by the use of a high fat diet. Mice were divided into four groups of control (C), treated control (TC), obese (O) and treated obese (TO). TC and TO groups received 8 mg/Kg/day of GT for 8 weeks, and weighted weekly, after what biochemical and histological parameters were measured. GT was used at doses of 100,150 and 200 µg/ml on 3T3L1, and staining with Oil-red-O was done for estimation of fat droplet accumulation.

Results

Body weight was found to be affected significantly by GT. Blood glucose levels did not show significant changes between groups, while triglycerides levels of the O group was significantly higher than the C group, but the TO group showed no significant difference with the C group upon GT treatment. Liver and visceral fat tissues showed more normalized tissue and less fat accumulation in the TO group. TO and TC groups showed an ameliorated morphologic state of liver tissues. GT was also able to decrease fat droplet formation in a dose-dependent manner.

Conclusions

Adding a minimal amount of GT to the daily consumption may have preventive effects on fat accumulation in healthy subjects, while in obese cases, GT shows significant therapeutic effect.

Evaluation of anti-obesity potential of aqueous extract of Achyranthes aspera Linn. in high fat diet induced obese rats

Background

Obesity, reached epidemic proportions globally is often associated with life threatening comorbidities. The unavailability of safe and effective long term medications for obesity in modern pharmacotherapy forces the scientific community to explore the potential of Ayurvedic traditional healers as they are considered safe and effective.

Objective

To explore the anti-obesity potential of aqueous extract of aerial parts ofAchyranthes asperaL. (AEAA), a traditional healer in high fat diet (HFD) induced obese rats.

Methods

AEAA was prepared and subjected to in-vitro pancreatic lipase inhibition assay and in-vivo anti-obesity studies. For in-vivo studies, HFD fed obese prone Wistar albino rats were divided into five experimental groups (Group II to VI): animals fed with standard pellet chow served as normal control (Group I) while, animals continued with HFD alone served as obese control (Group II); Group III, IV and V were administered AEAA at a dose of 100, 200 and 300 mg/kg b.w. respectively along with HFD; and animals administered orlistat (30 mg/kg bw) along with HFD served as standard control (Group VI). All the drugs were administered orally once a day for a period of 60 days. At the end of the experimental period various physical, biochemical and histopathological observations were made.

Results

In-vitro studies showed AEAA partially but not significantly inhibited the activity of pancreatic lipase. Data of in-vivo studies revealed, significant reduction in body weights, fat pad weights and organ weights upon AEAA treatment. Elevated levels of glucose, insulin, leptin, lipid profiles and antioxidant status were also brought back to normal.

Conclusion

The obtained results clearly suggested that AEAA possess pronounced anti-obesity potential.

Evidence of complex involvement of serotonergic genes with restrictive and binge purge subtypes of anorexia nervosa

OBJECTIVES

There is mixed evidence of association of serotoninergic genes with anorexia nervosa (AN), but substantial evidence for the involvement of serotonergic mechanisms in appetite control. This study was designed to investigate possible associations between the two subtypes of AN (Restricting-RAN, and Binge-purging-BPAN) and polymorphisms within five genes encoding for proteins involved in the serotoninergic system.

METHODS

In order to carry out this investigation we have conducted a case-control association study on 226 females meeting the criteria for AN, and 678 matched healthy females.

RESULTS

Our data show a significant association between polymorphisms with the gene encoding HTR2A with both AN subtypes, an association between polymorphisms within the genes encoding HTR1D and HTR1B with RAN, and an association between polymorphisms within the gene encoding HTR2C with BPAN. No associations were found for any polymorphisms of the serotonin transporter gene. This outcome indicates a substantial and complex inter-relationship between serotoninergic genes and AN.

CONCLUSIONS

Given these data we hypothesis that the expression or control of expression of several genes of the serotoninergic system, and interactions between these genes, could exert considerable influence over the specific symptomatology of the subtypes of AN.

Anti-Obesity effects of protopanaxdiol types of Ginsenosides isolated from the leaves of American ginseng (Panax quinquefolius L.) in mice fed with a high-fat diet

Effects of protopanaxdiol (PDG) and protopanaxatriol (PTG) types of ginsenosides isolated from the leaves of American ginseng on porcine pancreatic lipase activity were determined in vitro. PDG inhibited the pancreatic lipase activity in a dose-dependent manner at the concentrations of 0.25-1mg/ml. It inhibited hydrolysis of about 83.2% of triolein at about 1mg/ml of PDG. However, PTG showed no inhibitory activity. Therefore, anti-obesity activity of PDG was evaluated in mice fed a high-fat diet. The results demonstrated that PDG was effective in preventing and healing obesity, fatty liver and hypertriglyceridemia in mice fed with a high-fat diet.

Advances in anti-obesity therapeutics

Obesity is rapidly becoming an epidemic in developed countries. Currently available anti-obesity therapeutics are only modestly effective and are accompanied by significant adverse effects. In recent years, substantial advances have been made in the basic understanding of brain control of feeding behaviour and metabolism. As a result, several compounds have progressed to Phase III development, with additional compounds at various stages of Phase II development. Most of the late-stage development candidates are CNS agents, which reflects the consensus that the brain exerts a dominant control on feeding behaviour and peripheral metabolism through the autonomic nervous system. Homeostatic mechanisms encompassing hypothalamic/brainstem pathways have long been recognised in obesity research. In addition, non-homeostatic mechanisms encompassing the reward circuit and volitional control need to be targeted to control feeding behaviour and physical activity, especially in humans. While recognising the importance of CNS control, certain peripherally acting agents can affect mitochondrial metabolism, lipolysis, nutrient absorption or the vagal feedback pathway, such that these peripherally acting agents can potentially be combined with CNS agents to achieve maximal efficacy. It is expected that newer generations of anti-obesity therapeutics will be superior to existing agents and will facilitate lifestyle modification.

Determinantes psicobiológicos do comportamento alimentar: uma ênfase em fatores ambientais que contribuem para a obesidade

O comportamento alimentar é multideterminado e somente uma análise psicobiológica é capaz de abordar as interações entre os fatores fisiológicos, psicológicos, genéticos e condições ambientais de um indivíduo. Assim, a capacidade para controlar a ingestão requer mecanismos especializados para harmonizar informações fisiológicas do meio interno com informações nutricionais do ambiente externo. Dentre os fatores externos merece destaque a questão ligada à propaganda de alimentos e a influência cada vez maior da mídia na determinação da dieta dos indivíduos de países desenvolvidos ou em desenvolvimento. Assim, o presente trabalho tem por objetivo analisar as influencias dos fatores ambientais na determinação do comportamento alimentar humano, com especial ênfase naqueles fatores que podem predispor à obesidade.

A live-cell high-throughput screening assay for identification of fatty acid uptake inhibitors

We developed a live-cell high-throughput assay system using the baker's yeast Saccharomyces cerevisiae to screen for chemical compounds that will inhibit fatty acid uptake. The target for the inhibitors is a mammalian fatty acid transport protein (mmFATP2), which is involved in the fatty acid transport and activation pathway. The mmFATP2 was expressed in a S. cerevisiae mutant strain deficient in Fat1p-dependent fatty acid uptake and reduced in long-chain fatty acid activation, fat1Deltafaa1Delta. To detect fatty acid import, a fluorescent fatty acid analog, 4,4-difluoro-5-methyl-4-bora-3a,4a-diaza-s-indacene-3-dodecanoic acid (C1-BODIPY-C12), was incubated with cells expressing FATP2 in a 96-well plate. The mmFATP2-dependent C1-BODIPY-C12 uptake was monitored by measuring intracellular C1-BODIPY-C12 fluorescence on a microtiter plate reader, whereas extracellular fluorescence was quenched by a cell viability dye, trypan blue. Using this high-throughput screening method, we demonstrate that the uptake of the fluorescent fatty acid ligand was effectively competed by the natural fatty acid oleate. Inhibition of uptake was also demonstrated to occur when cells were pretreated with sodium azide or Triacsin C. This yeast live-cell-based assay is rapid to execute, inexpensive to implement, and has adequate sensitivity for high-throughput screening. The assay basis and limitations are discussed.

Anti-obesity Effect of PM-F2-OB, an Anti-obesity Herbal Formulation, on Rats Fed a High-Fat Diet

PM-F2-OB is one of the most well-known traditional herbal medicines that are frequently used for the treatment of obesity in Korea. The anti-obesity effect of PM-F2-OB on rats fed a high-fat diet was investigated through analyses of changes in body weight, kidney fat weight, and blood biochemicals including cholesterol, free fatty acid, BUN, creatinine, HDL, LDL, phospholipids, SGOT, SGPT, total lipids, and triglycerides. The subjects in this study were divided into four groups: a normal group with a standard diet (N); a PM-F2-OB treatment group fed a standard diet (N+PM-F2-OB); a control group fed a high-fat diet (C); and a PM-F2-OB treatment group fed a high-fat diet (C+PM-F2-OB). There were no significant differences in body weight change between the N and N+PM-F2-OB treatments. Also, there was no significant difference in the amount of food intake between the C and C+PM-F2-OB treatments. These results suggest that PM-F2-OB has no significant toxicity and does not induce a dislike for that diet due to its smell or taste. Rats were administered a high-fat diet (20% (w/w)) for six weeks to induce obesity. The study shows that PM-F2-OB significantly prevented increases in body weight, cholesterol, LDL and total lipids that resulted from the high-fat diet. PM-F2-OB also decreased kidney fat weight and free fatty acid, phospholipid, and triglyceride concentrations induced by the high-fat diet to level equals or below the normal diet group. It was concluded from the results that PM-F2-OB has a distinct anti-obesity effect.

Neuropeptides in hypothalamic neuronal disorders

A few examples of hypothalamic, peptidergic disorders leading to clinical signs and symptoms are presented in this review. Increased activity of corticotropin-releasing hormone (CRH) neurons in the paraventricular nucleus (PVN) and decreased activity of the vasopressin neurons in the biological clock and of the thyroxine-releasing hormone (TRH) neurons in the PVN contribute to the signs and symptoms of depression. In men, the central nucleus of the bed nucleus of the stria terminalis (BSTc) is about twice as large and contains twice as many somatostatin neurons as in women. In transsexuals this sex difference is reversed, pointing to a role of this structure in gender. Luteinizing hormone-releasing hormone (LHRH) neurons are formed in the fetal olfactory placade and migrate along the terminal nerve fibers into the hypothalamus. In Kallmann's syndrome the migration process of the LHRH (gonadotropin-releasing hormone) neurons is aborted, which explains the joint occurrence of hypogonadotropic hypogonadism and anosmia in this syndrome. In postmenopausal women, the neurons of the infundibular nucleus hypertrophy and become hyperactive because of the disappearance of the estrogen feedback and contain hyperactive peptidergic neurons. Climacteric flushes may be caused by hyperactivity of the neurokinin-B or LHRH neurons in this nucleus. The hypocretin (orexin) neurons in the perifornical area are involved in sleep. In narcolepsy with cataplexy, a loss of these neurons, probably due to an autoimmune process, is found. Obese subjects with a mutation in the gene that encodes for leptin, the preproghrelin gene, or the alpha-melanocyte-stimulating hormone (alpha-MSH) gene have been described. Decreased numbers and activity of the oxytocin neurons in the PVN may be responsible for the absence of satiety in Prader-Willi syndrome. Moreover, a glucocorticoid receptor polymorphism is associated with obesitas and dysregulation of the hypothalamus-pituitary-adrenal axis. In contrast, two single nucleotide polymorphisms (SNPs) of the AGRP gene have been associated with anorexia nervosa.

β-Alanine dipeptides as MC4R agonists

beta-Alanine derivative 2 (IC(50)=16 nM) and related compounds were found to be potent MC4R agonists.

Antiobesity effects of chronic cannabinoid CB1 receptor antagonist treatment in diet-induced obese mice

We determined the effect of a cannabinoid CB1 receptor antagonist (AM-251; N-(Piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide) on food intake, body weight and adipose tissue mass in Western diet-induced obese (DIO) mice using a chronic, interrupted, oral dosing paradigm. The dosing paradigm was 2 weeks on treatment (treatment 1), 2 weeks off-treatment, followed by 2 weeks on treatment (treatment 2). During treatment 1 and treatment 2, food intake and body weight were reduced after a single dose. At 30 mg/kg/day, anorectic efficacy was maintained through 12 days (treatment 1) and 7 days (treatment 2). Body weight of AM-251-treated mice remained less than vehicle-treated mice throughout treatment 1 and treatment 2. Administration of AM-251 reduced inguinal subcutaneous, retroperitoneal and mesenteric adipose tissue mass. Antiobesity effects of AM-251 were lost during the off-treatment period, and hyperphagia was observed in treated animals. With re-initiation of AM-251 treatment, mice again responded to the effects of the compound. These results support the hypothesis that chronic treatment of obese individuals with cannabinoid CB1 receptor antagonists is a viable pharmacologic approach to sustained weight loss.

A major predisposition locus for severe obesity, at 4p15-p14

Although the predisposition to morbid obesity is heritable, the identities of the disease-causing genes are largely unknown. Therefore, we have conducted a genomewide search with 628 markers, using multigenerational Utah pedigrees to identify genes involved in predisposition to obesity. In the genomewide search, we identified a highly significant linkage to high body-mass index in female patients, at D4S2632, with a multipoint heterogeneity LOD (HLOD) score of 6.1 and a nonparametric linkage (NPL) score of 5.3. To further delineate the linkage, we increased both the marker density around D4S2632 and the size of our pedigree data set. As a result, the linkage evidence increased to a multipoint HLOD score of 9.2 (at D4S3350) and an NPL score of 11.3. Evidence from almost half of the families in this analysis support this linkage, and therefore the gene in this region might account for a significant percentage of the genetic predisposition to severe obesity in females. However, further studies are necessary to clarify the effect that this gene has in males and in the general population.

Pharmacotherapy of obesity: targets and perspectives

The search for anti-obesity agents has become one of the most exciting areas in drug discovery. Subsequent to an enormous increase in the number of possible molecular targets, the focus has shifted from target identification to target validation. Because important biological functions such as the regulation of energy intake and expenditure are controlled by complex systems, an improved understanding of pathophysiology is a prerequisite for the selection of successful development candidates for the treatment of obesity. Although most of the information on the regulation of energy balance has been obtained from rodents, various monogenic forms of human obesity provide clinical proof of concept for some of these mechanisms. However, it is still not known which are the most promising clinical approaches to lowering body weight and subsequently reducing morbidity and mortality.