Effects of GLP-1 on appetite and weight

Therapeutic Potential of Lentivirus-Mediated Glucagon-Like Peptide-1 Gene Therapy for Diabetes

Postprandial glucose-induced insulin secretion from the islets of Langerhans is facilitated by glucagon-like peptide-1 (GLP-1)-a metabolic hormone with insulinotropic properties. Among the variety of effects it mediates, GLP-1 induces delta cell secretion of somatostatin, inhibits alpha cell release of glucagon, reduces gastric emptying, and slows food intake. These events collectively contribute to weight loss over time. During type 2 diabetes (T2DM), however, the incretin response to glucose is reduced and accompanied by a moderate reduction in GLP-1 secretion. To compensate for the reduced incretin effect, a human immunodeficiency virus-based lentiviral vector was generated to deliver DNA encoding human GLP-1 (LentiGLP-1), and the anti-diabetic efficacy of LentiGLP-1 was tested in a high-fat diet/streptozotocin-induced model of T2DM. Therapeutic administration of LentiGLP-1 reduced blood glucose levels in obese diabetic Sprague Dawley rats, along with improving insulin sensitivity and glucose tolerance. Normoglycemia was correlated with increased blood GLP-1 and pancreatic beta cell regeneration in LentiGLP-1-treated rats. Plasma triglyceride levels were also normalized after LentiGLP-1 injection. Collectively, these data suggest the clinical potential of GLP-1 gene transfer therapy for the treatment of T2DM.

The role of gut in type 2 diabetes mellitus during whole body gamma irradiation in high-fat diet Wistar rats

PURPOSE

The effects of a low rate (100 mGy/min) fractionated whole body gamma irradiation (FWBGI) at different doses were assessed using a real-time PCR technique on the expression of some target genes implicated in the development of type 2 diabetes mellitus in high-fat diet (HFD) Wistar rats.

METHOD

HFD Wistar rats were exposed to different doses (12, 24 and 48 Gy) divided into 24 fractions (three times a week for two months), thus, the daily doses were 0.5, 1, 2 Gy, respectively. Total RNA was extracted and the expression of target genes was measured in the four intestinal segments (duodenum, jejunum, ileum and colon).

RESULTS

The pre-diabetic state already induced by HFD was found to be improved by irradiation exposure. This irradiation effect occurs mainly via altered anti-diabetic gene expressions (mRNA and protein levels) of the incretin glucagon-like peptide-1 (GLP-1) overall bowel segments except the colon which has its own specific response to irradiation exposure by the induction of the insulin receptor substrate 4 (IRS-4) and the uncoupling protein 3 (UCP3).

CONCLUSIONS

Results could be of great importance suggesting for the first time, a protective role for FWBGI on HFD animal models by increasing GLP-1 and UCP3 levels.

Duodenal and ileal glucose infusions differentially alter gastrointestinal peptides, appetite response, and food intake: a tube feeding study

Background: Activation of the ileal brake through the delivery of nutrients into the distal small intestine to promote satiety and suppress food intake provides a new target for weight loss. Evidence is limited, with support from naso-ileal lipid infusion studies.Objective: The objective of the study was to investigate whether glucose infused into the duodenum and ileum differentially alters appetite response, food intake, and secretion of satiety-related gastrointestinal peptides.Design: Fourteen healthy male participants were randomly assigned to a blinded 4-treatment crossover, with each treatment of single-day duration. On the day before the intervention (day 0), a 380-cm multilumen tube (1.75-mm diameter) with independent port access to the duodenum and ileum was inserted, and position was confirmed by X-ray. Subsequently (days 1-4), a standardized breakfast meal was followed midmorning by a 90-min infusion of isotonic glucose (15 g, 235 kJ) or saline to the duodenum or ileum. Appetite ratings were assessed with the use of visual analog scales (VASs), blood samples collected, and ad libitum energy intake (EI) measured at lunch, afternoon snack, and dinner.Results: Thirteen participants completed the 4 infusion days. There was a significant effect of nutrient infused and site (treatment × time, P < 0.05) such that glucose-to-ileum altered VAS-rated fullness, satisfaction, and thoughts of food compared with saline-to-ileum (Tukey's post hoc, P < 0.05); decreased ad libitum EI at lunch compared with glucose-to-duodenum [-22%, -988 ± 379 kJ (mean ± SEM), Tukey's post hoc, P < 0.05]; and increased glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) compared with all other treatments (Tukey's post hoc, P < 0.05).Conclusions: Macronutrient delivery to the proximal and distal small intestine elicits different outcomes. Glucose infusion to the ileum increased GLP-1 and PYY secretion, suppressed aspects of VAS-rated appetite, and decreased ad libitum EI at a subsequent meal. Although glucose to the duodenum also suppressed appetite ratings, eating behavior was not altered. This trial was registered at www.anzctr.org.au as ACTRN12612000429853.

Molecular bases of anorexia nervosa, bulimia nervosa and binge eating disorder: shedding light on the darkness

Eating-disorders (EDs) consequences to human health are devastating, involving social, mental, emotional, physical and life-threatening aspects, concluding on impairment and death in cases of extreme anorexia nervosa. It also implies that people suffering an ED need to find psychiatric and psychological help as soon as possible to achieve a fully physical and emotional recovery. Unfortunately, to date, there is a crucial lack of efficient clinical treatment to these disorders. In this review, we present an overview concerning the actual pharmacological and psychological treatments, the knowledge of cells, circuits, neuropeptides, neuromodulators and hormones in the human brain- and other organs- underlying these disorders, the studies in animal models and, finally, the genetic approaches devoted to face this challenge. We will also discuss the need for new perspectives, avenues and strategies to be developed in order to pave the way to novel and more efficient therapeutics.

Novel GLP-1 Analog Supaglutide Reduces HFD-Induced Obesity Associated with Increased Ucp-1 in White Adipose Tissue in Mice

GLP-1, an important incretin hormone plays an important role in the regulation of glucose homeostasis. However, the therapeutic use of native GLP-1 is limited due to its short half-life. We recently developed a novel GLP-1 mimetics (supaglutide) by genetically engineering recombinant fusion protein production techniques. We demonstrated that this formulation possessed long-lasting GLP-1 actions and was effective in glycemic control in both type 1 and type 2 diabetes rodent models. Here, we investigated the effects of supaglutide in regulating energy homeostasis in obese mice. Mice were fed with high-fat diet (HFD) for 6 months to induce obesity and then subjected to supaglutide treatment (300 μg/kg, bi-weekly for 4 weeks), and placebo as control. Metabolic conditions were monitored and energy expenditure was assessed by indirect calorimetry (CLAMS). Cold tolerance test was performed to evaluate brown-adipose tissue (BAT) activities in response to cold challenge. Glucose tolerance and insulin resistance were evaluated by intraperitoneal glucose tolerance test and insulin tolerance tests. Liver and adipose tissues were collected for histology analysis. Expression of uncoupling protein 1(Ucp1) in adipose tissues was evaluated by Western blotting. We found that supaglutide treatment reduced body weight, which was associated with reduced food intake. Compared to the placebo control, supaglutide treatment improved lipid profile, i.e., significantly decreased circulating total cholesterol levels, declined serum triglyceride, and free fatty acid levels. Importantly, the intervention significantly reduced fatty liver, decreased liver triglyceride content, and concomitantly ameliorated liver injury exemplified by declined hepatic alanine aminotransferase (ALT) and aspartic transaminase (AST) content. Remarkably, supaglutide reduced hepatic lipid accumulation and altered morphometry in favor of small adipocytes in fat. This is consistent with the observation that supaglutide increased tolerance of the mice to cold environment associated with up-regulation of Ucp1 in the inguinal fat. Furthermore, supaglutide improved glucose tolerance, and insulin sensitivity in the obese mice suggesting improved glucose and energy homeostasis. Our findings suggest that supaglutide exerts beneficial effect on established obesity through reducing energy intake and is associated with brown remodeling of white adipose tissue.

The incretin system ABCs in obesity and diabetes - novel therapeutic strategies for weight loss and beyond

Incretins are gastrointestinal-derived hormones released in response to a meal playing a key role in the regulation of postprandial secretion of insulin (incretin effect) and glucagon by the pancreas. Both incretins, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 (GLP-1), have several other actions by peripheral and central mechanisms. GLP-1 regulates body weight by inhibiting appetite and delaying gastric, emptying actions that are dependent on central nervous system GLP-1 receptor activation. Several other hormones and gut peptides, including leptin and ghrelin, interact with GLP-1 to modulate appetite. GLP-1 is rapidly degraded by the multifunctional enzyme dipeptidyl peptidase-4 (DPP-4). DPP-4 is involved in adipose tissue inflammation, which is associated with insulin resistance and diabetes progression, being a common pathophysiological mechanism in obesity-related complications. Furthermore, the incretin system appears to provide the basis for understanding the high weight loss efficacy of bariatric surgery, a widely used treatment for obesity, often in association with diabetes. The present review brings together new insights into obesity pathogenesis, integrating GLP-1 and DPP-4 in the complex interplay between obesity and inflammation, namely, in diabetic patients. This in turn will provide the basis for novel incretin-based therapeutic strategies for obesity and diabetes with promising benefits in addition to weight loss. © 2016 World Obesity.

Daily Eating Patterns and Their Impact on Health and Disease

Cyclical expression of cell-autonomous circadian clock components and key metabolic regulators coordinate often discordant and distant cellular processes for efficient metabolism. Perturbation of these cycles, either by genetic manipulation, disruption of light/dark cycles, or, most relevant to the human population, via eating patterns, contributes to obesity and dysmetabolism. Time-restricted feeding (TRF), during which time of access to food is restricted to a few hours, without caloric restriction, supports robust metabolic cycles and protects against nutritional challenges that predispose to obesity and dysmetabolism. The mechanism by which TRF imparts its benefits is not fully understood but likely involves entrainment of metabolically active organs through gut signaling. Understanding the relationship of feeding pattern and metabolism could yield novel therapies for the obesity pandemic.

Effects of supplementing a milk replacer with sodium butyrate or tributyrin on performance and metabolism of Holstein calves

The effects of butyrate supplementation in diets of calves are inconsistent in the literature. Fifty-one Holstein calves (45.7 ± 5.8 kg of bodyweight and 11.8 ± 3.1 days of age; mean ± s.d.) were randomly allocated to three treatments to assess the effects of supplementing the milk replacer at 0.3% dry matter with butyrate in the form of sodium butyrate or tributyrin compared with no supplementation (CTR). Calves were fed 4 L/day of milk replacer (25% crude protein and 19.2% ether extract) and starter feed (20% crude protein and 3.8% ether extract) ad libitum over a period of 6 weeks. Individual intake was measured daily and bodyweight and blood β-hydroxybutyrate, glucose-like peptide-1, glucose and insulin were measured fortnightly. A glucose tolerance test was performed on Days 0 and 35 of the study. No effects of butyrate supplementation were found on starter and total dry matter intake. CTR calves had greater average daily gain than tributyrin calves. CTR calves tended to have greater final bodyweight than tributyrin and sodium butyrate calves. Gain : feed ratio tended to be greater for CTR calves. There were no differences in plasma glucose, insulin, β-hydroxybutyrate and glucose-like peptide-1 concentrations throughout among treatments the study. During the glucose tolerance test, no differences on insulin sensitivity were found among treatments. In conclusion, no apparent advantages of supplementing milk replacer with sodium butyrate or tributyrin were found on performance and glucose metabolism in calves.

Mexico City normal weight children exposed to high concentrations of ambient PM2.5 show high blood leptin and endothelin-1, vitamin D deficiency, and food reward hormone dysregulation versus low pollution controls. Relevance for obesity and Alzheimer disease

Millions of Mexico, US and across the world children are overweight and obese. Exposure to fossil-fuel combustion sources increases the risk for obesity and diabetes, while long-term exposure to fine particulate matter (PM2.5) and ozone (O3) above US EPA standards is associated with increased risk of Alzheimer's disease (AD). Mexico City Metropolitan Area children are chronically exposed to PM2.5 and O3 concentrations above the standards and exhibit systemic, brain and intrathecal inflammation, cognitive deficits, and Alzheimer disease neuropathology. We investigated adipokines, food reward hormones, endothelial dysfunction, vitamin D and apolipoprotein E (APOE) relationships in 80 healthy, normal weight 11.1±3.2 year olds matched by age, gender, BMI and SES, low (n: 26) versus high (n:54) PM2.5 exposures. Mexico City children had higher leptin and endothelin-1 (p<0.01 and p<0.000), and decreases in glucagon-like peptide-1 (GLP 1), ghrelin, and glucagon (<0.02) versus controls. BMI and leptin relationships were significantly different in low versus high PM2.5 exposed children. Mexico City APOE 4 versus 3 children had higher glucose (p=0.009). Serum 25-hydroxyvitamin D<30 ng/mL was documented in 87% of Mexico City children. Leptin is strongly positively associated to PM 2.5 cumulative exposures. Residing in a high PM2.5 and O3 environment is associated with 12h fasting hyperleptinemia, altered appetite-regulating peptides, vitamin D deficiency, and increases in ET-1 in clinically healthy children. These changes could signal the future trajectory of urban children towards the development of insulin resistance, obesity, type II diabetes, premature cardiovascular disease, addiction-like behavior, cognitive impairment and Alzheimer's disease. Increased efforts should be made to decrease pediatric PM2.5 exposures, to deliver health interventions prior to the development of obesity and to identify and mitigate environmental factors influencing obesity and Alzheimer disease.

Does Whole Grain Consumption Alter Gut Microbiota and Satiety?

This review summarizes recent studies examining whole grain consumption and its effect on gut microbiota and satiety in healthy humans. Studies comparing whole grains to their refined grain counterparts were considered, as were studies comparing different grain types. Possible mechanisms linking microbial metabolism and satiety are described. Clinical trials show that whole grain wheat, maize, and barley alter the human gut microbiota, but these findings are based on a few studies that do not include satiety components, so no functional claims between microbiota and satiety can be made. Ten satiety trials were evaluated and provide evidence that whole oats, barley, and rye can increase satiety, whereas the evidence for whole wheat and maize is not compelling. There are many gaps in the literature; no one clinical trial has examined the effects of whole grains on satiety and gut microbiota together. Once understanding the impact of whole grains on satiety and microbiota is more developed, then particular grains might be used for better appetite control. With this information at hand, healthcare professionals could make individual dietary recommendations that promote satiety and contribute to weight control.

Therapeutic stimulation of GLP-1 and GIP protein with DPP-4 inhibitors for type-2 diabetes treatment

Dipeptidyl peptidase-4 (DPP-4) inhibition is a new treatment for type-2 diabetes. DPP-4 inhibition increases levels of active GLP-1. GLP-1 enhances insulin secretion and diminishes glucagon secretion, in this manner reducing glucose concentrations in blood. A number of DPP-4 inhibitors are under clinical development. However, the durability and long-term safety of DPP-4 inhibition remain to be established. These synthetic DPP-4 inhibitors are showing some side effects. Herbal medicines are alternative medicine over synthetic drugs that can relieve the patients. Various research studies have been carried all over the world to evaluate the efficacy of herbs in the treatment of Type II diabetes mellitus. For a long time type II diabetes mellitus has been treated orally with herbal medicines, because plant products are frequently prescribed due to their less toxicity than conventional medicines.

The stomach-brain axis

The stomach has distinct functions in relation to the ingestion and handling of solids and liquids. These functions include storage of the food before it is gradually emptied into the duodenum, mechanical crushing of larger food particles to increase the surface area, secretion of an acidic enzyme rich gastric juice and mixing the ingested food with the gastric juice. In addition, the stomach 'senses' the composition of the gastric content and this information is passed via the vagal nerve to the lateral hypothalamus and the limbic system, most likely as palatability signals that influence eating behaviour. Other sensory qualities related to the stimulation of gastric tension receptors are satiety and fullness. Receptors that respond to macronutrient content or gastric wall tension influence appetite and meal related hormone responses. The ingestion of food - in contrast to an infusion of nutrients into the stomach - has distinct effects on the activation of specific brain regions. Brain areas such as thalamus, amygdala, putamen and praecuneus are activated by the ingestion of food. Gastric nutrient infusion evokes greater activation in the hippocampus and anterior cingulate. The brain integrates these interrelated neural and hormonal signals arising from the stomach as well as visual, olfactory and anticipatory stimuli that ultimately influence eating and other behavioural patterns. Furthermore, there is now good evidence from experimental studies that gastric afferents influence mood, and animal studies point towards the possibility that gastric dysfunction may be a risk factor for mood disorders such as anxiety and depression. The stomach is also not only colonised by Helicobacter pylori but a large array of bacteria. While there is sufficient evidence to suggest that H. pylori may alter caloric intake and mood, the role of other gastric microbiome for the brain function is unknown. To address this appropriate targeted gastric microbiome studies would be required instead of widely utilised opportunistic stool microbiome studies. In summary, it is now well established that there are important links between the brain and the stomach that have significant effects on gastric function. However, the stomach also influences the brain. Disturbances in the crosstalk between the stomach and the brain may manifest as functional GI disorders while disturbances in the stomach-brain communication may also result in an altered regulation of satiety and as a consequence may affect eating behaviour and mood. These observations may enable the identification of novel therapies targeted at the gastroduodenum that positively alter brain function and treat or prevent conditions such as obesity or functional gastrointestinal disorders.

Glucagon-like peptide 1 receptor (GLP1R) haplotypes correlate with altered response to multiple antipsychotics in the CATIE trial

Glucagon-like peptide 1 receptor (GLP1R) signaling has been shown to have antipsychotic properties in animal models and to impact glucose-dependent insulin release, satiety, memory, and learning in man. Previous work has shown that two coding mutations (rs6923761 and rs1042044) are associated with altered insulin release and cortisol levels. We identified four frequently occurring haplotypes in Caucasians, haplotype 1 through haplotype 4, spanning exons 4-7 and containing the two coding variants. We analyzed response to antipsychotics, defined as predicted change in PANSS-Total (dPANSS) at 18 months, in Caucasian subjects from the Clinical Antipsychotic Trial of Intervention Effectiveness treated with olanzapine (n=139), perphenazine (n=78), quetiapine (n=14), risperidone (n=143), and ziprasidone (n=90). Haplotype trend regression analysis revealed significant associations with dPANSS for olanzapine (best p=0.002), perphenazine (best p=0.01), quetiapine (best p=0.008), risperidone (best p=0.02), and ziprasidone (best p=0.007). We also evaluated genetic models for the two most common haplotypes. Haplotype 1 (uniquely including the rs1042044 [Leu(260)] allele) was associated with better response to olanzapine (p=0.002), and risperidone (p=0.006), and worse response to perphenazine (p=.03), and ziprasidone (p=0.003), with a recessive genetic model providing the best fit. Haplotype 2 (uniquely including the rs6923761 [Ser(168)] allele) was associated with better response to perphenazine (p=0.001) and worse response to olanzapine (p=.02), with a dominant genetic model providing the best fit. However, GLP1R haplotypes were not associated with antipsychotic-induced weight gain. These results link functional genetic variants in GLP1R to antipsychotic response.