GLUCAGON-LIKE PEPTIDE-1 AFFECTS TASTE PERCEPTION DIFFERENTLY IN WOMEN: A RANDOMIZED, PLACEBO-CONTROLLED CROSSOVER STUDY

A randomized controlled trial investigating the effect of liraglutide on self-reported liking and neural responses to food stimuli in participants with obesity

BACKGROUND/OBJECTIVES

Obesity is a complex condition and the mechanisms involved in weight gain and loss are not fully understood. Liraglutide, a GLP-1 receptor agonist, has been demonstrated to successfully promote weight loss in patients with obesity (OB). Yet, it is unclear whether the observed weight loss is driven by an alteration of food liking. Here we investigated the effects of liraglutide on food liking and the cerebral correlates of liking in OB.

SUBJECTS/METHODS

This study was a randomized, single-center, double-blind, placebo-controlled, parallel group, prospective clinical trial. 73 participants with OB and without diabetes following a multidisciplinary weight loss program, were randomly assigned (1:1) to receive liraglutide 3.0 mg (37.40 ± 11.18 years old, BMI = 35.89 ± 3.01 kg) or a placebo (40.04 ± 14.10 years old, BMI = 34.88 ± 2.87 kg) subcutaneously once daily for 16 weeks.

INTERVENTIONS/METHODS

We investigated liking during food consumption. Participants reported their hedonic experience while consuming a high-calorie food (milkshake) and a tasteless solution. The solutions were administered inside the scanner with a Magnetic Resonance Imaging (MRI)-compatible gustometer to assess neural responses during consumption. The same procedure was repeated during the pre- and post-intervention sessions.

RESULTS

None of the effects involving the intervention factor reached significance when comparing liking between the pre- and post-intervention sessions or groups. Liking during food reward consumption was associated with the activation of the ventromedial prefrontal cortex (vmPFC) and the amygdala. The liraglutide group lost more weight (BMI post-pre = -3.19 ± 1.28 kg/m2) than the placebo group (BMI post-pre = -0.60 ± 1.26 kg/m2).

CONCLUSIONS

These results suggest that liraglutide leads to weight loss without self-report or neural evidence supporting a concomitant reduction of food liking in participants with OB.

The role of glucagon-like peptide 1 (GLP-1) in addictive disorders

Drug-, alcohol- and tobacco use disorders are a global burden affecting millions of people. Despite decades of research, treatment options are sparse or missing, and relapse rates are high. Glucagon-like peptide-1 (GLP-1) is released in the small intestines, promotes blood glucose homeostasis, slows gastric emptying, and reduces appetite. GLP-1 receptor agonists approved for treating type 2 diabetes mellitus and obesity, have received attention as a potential anti-addiction treatment. Studies in rodents and non-human primates have demonstrated a reduction in intake of alcohol and drugs of abuse, and clinical trials have been initiated to investigate whether the preclinical findings can be translated to patients. This review will give an overview of current findings and discuss the possible mechanisms of action. We suggest that effects of GLP-1 in alcohol- and substance use disorder is mediated centrally, at least partly through dopamine signalling, but precise mechanisms are still to be uncovered.

Ghrelin and Glucagon-Like Peptide-1: A Gut-Brain Axis Battle for Food Reward

Eating behaviors are influenced by the reinforcing properties of foods that can favor decisions driven by reward incentives over metabolic needs. These food reward-motivated behaviors are modulated by gut-derived peptides such as ghrelin and glucagon-like peptide-1 (GLP-1) that are well-established to promote or reduce energy intake, respectively. In this review we highlight the antagonizing actions of ghrelin and GLP-1 on various behavioral constructs related to food reward/reinforcement, including reactivity to food cues, conditioned meal anticipation, effort-based food-motivated behaviors, and flavor-nutrient preference and aversion learning. We integrate physiological and behavioral neuroscience studies conducted in both rodents and human to illustrate translational findings of interest for the treatment of obesity or metabolic impairments. Collectively, the literature discussed herein highlights a model where ghrelin and GLP-1 regulate food reward-motivated behaviors via both competing and independent neurobiological and behavioral mechanisms.

ADROPIN - POTENTIAL LINK IN CARDIOVASCULAR PROTECTION FOR OBESE MALE TYPE 2 DIABETES MELLITUS PATIENTS TREATED WITH LIRAGLUTIDE

The aim of this study was to determine plasma adropin concentration and parameters of insulin resistance in obese male type 2 diabetes mellitus (T2DM) patients before and after 3-month liraglutide treatment. In this interventional study, we enrolled 15 obese male T2DM patients with body mass index (BMI) >35 kg/m2, uncontrolled disease and HbA1c >7.5%, having previously taken taking two oral antidiabetic drugs. We modified their therapy to metformin and liraglutide for the next three months. After three months of liraglutide treatment, we observed significant decrease in body weight (from 111.5±18.7 kg to 109.2±17.5 kg, p=0.016) and BMI (from 40.9±7.3 to 40.1±7.0 kg/m2, p=0.021). Plasma adropin concentration increased significantly (p=0.003) compared with baseline. Fasting plasma insulin level decreased from 17.79±6.53 to 13.38±3.51 mU/L (p=0.002), fasting plasma glucose level decreased from 8.66±3.07 to 7.41±2.21 mmol/L (p=0.004) and HbA1c decreased from 7.98±0.70% to 7.26±0.36% (p=0.003). Insulin resistance presented as HOMA-IR decreased significantly from 7.30±5.19 to 4.52±2.61 (p=0.002). Systolic blood pressure, lipid status, liver and kidney function improved, but not reaching statistical significance. Treating obese male T2DM patients with liraglutide resulted in a significantly higher plasma adropin concentration, significant weight loss and improved parameters of insulin resistance, i.e. decreased fasting plasma insulin, plasma glucose levels and HOMA-IR.

Methodological Errors in Clinical Studies Published by Medical Journals of Ex-Yugoslav Countries

INTRODUCTION

Certain methodological principles should be inexcusably followed when designing clinical or observational research to avoid bias and presentation of results that do not reflect the truth about the phenomenon that is the object of the study.

AIM

The aim of this study was to compare the methodological quality of clinical trials and observational studies published in medical journals from ex-Yugoslav countries indexed in Pubmed/MEDLINE.

METHODS

Clinical studies published in medical journals of ex-Yugoslav countries were retrieved from the Pubmed/MEDLINE database, and the sample for analysis was randomly chosen from the retrieved publications. The rate of the most common errors in the design of clinical/observational studies was established by a careful reading of the sampled publications and their checking against predefined criteria.

RESULTS

The studies published in two countries that are now member states of the European Union (Slovenia and Croatia) have significantly higher citation rates, impact factor, and methodological quality scores than studies from other ex-Yugoslav countries. While publications from Croatia show clear improvement trend throughout the last two decades, which is visible also in the last 10 years in Slovenia and Bosnia and Herzegovina, quality of clinical research published in journals from Serbia was stagnating in the same period.

CONCLUSIONS

There are significant differences in methodological quality and scientometric characteristics of clinical research published in medical journals of ex-Yugoslav countries that could be mitigated by more intensive training of clinical researchers in statistics and research design, as well as by more rigorous editorial practices.