Alpha-Melanocyte-Stimulating Hormone and Agouti-Related Protein: Do They Play a Role in Appetite Regulation in Childhood Obesity?

Gut microbiota and childhood malnutrition: Understanding the link and exploring therapeutic interventions

Childhood malnutrition is a metabolic condition that affects the physical and mental well-being of children and leads to resultant disorders in maturity. The development of childhood malnutrition is influenced by a number of physiological and environmental factors including metabolic stress, infections, diet, genetic variables, and gut microbiota. The imbalanced gut microbiota is one of the main environmental risk factors that significantly influence host physiology and childhood malnutrition progression. In this review, we have evaluated the gut microbiota association with undernutrition and overnutrition in children, and then the quantitative and qualitative significance of gut dysbiosis in order to reveal the impact of gut microbiota modification using probiotics, prebiotics, synbiotics, postbiotics, fecal microbiota transplantation, and engineering biology methods as new therapeutic challenges in the management of disturbed energy homeostasis. Understanding the host-microbiota interaction and the remote regulation of other organs and pathways by gut microbiota can improve the effectiveness of new therapeutic approaches and mitigate the negative consequences of childhood malnutrition.

Serum Appetite-Regulating Hormone Levels in Cystic Fibrosis Patients: Influence of the Disease Severity and the Type of Bacterial Infection-A Pilot Study

Cystic fibrosis (CF) belongs to the most common inherited diseases. The severity of the disease and chronic bacterial infections are associated with a lower body index, undernutrition, higher number of pulmonary exacerbations, more hospital admissions, and increased mortality. The aim of our study was to determine the impact of the severity of the disease and the type of bacterial infection in 38 CF patients on the serum level of appetite-regulating hormones including leptin, ghrelin, neuropeptide Y, agouti-signaling protein, proopiomelanocortin, kisspeptin, putative protein Y, and α-melanocyte-stimulating hormone. The patients were divided according to the severity of the disease according to spirometry and the type of chronic bacterial infection. We found that leptin level was significantly higher in patients with severe CF than in patients with mild disease (20.02 ± 8.09 vs. 12.38 ± 6.03 ng/mL, p = 0.028). Furthermore, leptin level was elevated in patients with chronic infection with Pseudomonas aeruginosa compared to uninfected participants (15.74 ± 7.02 vs. 9.28 ± 1.72 ng/mL, p = 0.043). The severity of the disease and the type of bacterial infection did not affect the levels of other appetite-regulating hormones. Moreover, we found a positive correlation between pro-inflammatory interleukin-6 and leptin level (p = 0.0426, R = 0.333). Taken together, our results indicate that both the severity of the disease and the type of bacterial infection are associated with elevated leptin levels in CF patients. Future CF treatment strategies should consider possible disturbances in the hormones that regulate appetite and the factors that influence their levels.

Adipocytokine and appetite-regulating hormone response to weight loss in adolescents with obesity: Impact of weight loss magnitude

OBJECTIVE

The aim of this study was to investigate the association between the magnitude of weight loss (WL) and serum concentrations of the main adipocytokines and appetite-regulating hormones in adolescents with obesity.

METHODS

After completion of informed consent,108 adolescents with obesity (14-19 y of age; postpubertal) were submitted to clinical, nutritional, psychological, physical exercise, and physiotherapy support for 1 y. Body composition (BC) and plasma levels of neuropeptides (neuropeptide Y [NPY], agouti-related peptide [AgRP], and α-melanocyte-stimulating hormone [α-MSH]) and leptin were measured at baseline and post-intervention.

RESULTS

After therapy, adolescents who lost <10% body weight and <10% body weight (were compared. Both groups presented improvements in BC and reduced leptin. The Δα-MSH, Δα-MSH/AgRP ratio, and Δα-MSH/NPY ratio were lower and AgRP and NPY variations were higher in the low weight loss group. The leptin concentration was close to normal in the high weight loss only. The ΔWeight, Δα-MSH and Δleptin were associated with body fat loss by multiple linear regressions for all samples.

CONCLUSION

Weight loss >10% seems to reverse obesity-induced hyperleptinemia while stabilizing the neuropeptides that control appetite in adolescents with obesity. We were able to produce a prognostic mathematical model to predict body fat loss using weight, leptin, and α-MSH variations.

Changes in Appetite Regulation-Related Signaling Pathways in the Brain of Mice Supplemented with Non-nutritive Sweeteners

Non-nutritive sweeteners (NNSs) are commonly used to prevent weight gain and development of metabolic diseases associated with consumption of high-energy diets. Recent studies have demonstrated that these compounds may have unwanted detrimental effects under specific circumstances in vivo. In particular, an association between NNS consumption and changes in signaling pathways involved in the hunger-satiety system in the brain has been reported. Nonetheless, the extent of alterations in brain signaling pathways associated with consumption of these compounds has not been determined. The objective of this study was to determine the effect of frequent consumption of NNSs on the expression of proteins involved in signaling pathways related to appetite control in the brain in vivo. Eight-week-old BALB/c mice were supplemented with sucrose, sucralose, or steviol glycosides in their daily drinking water for 6 weeks. Subsequently, total brain protein extracts were used to analyze the expression of total and phosphorylated JAK2, STAT5, ERK 1/2, JNK, as well as SHP-2 and POMC, by western blot. Serum concentrations of leptin and α-MSH were quantified by ELISA. Results show that consumption of NNSs promotes significant changes in these signaling pathways, reducing the expression of pSTAT5/STAT5, pERK 1/2, SHP-2, and pJNK/JNK in male mice supplemented with steviol glycosides. Furthermore, consumption of steviol glycosides induced a decrease of α-MSH in male mice. In contrast, steviol glycosides induced overexpression of pSTAT5, pERK, and SHP-2 in females. These data suggest that chronic consumption of NNSs promotes sex-specific changes in signaling pathways related to the central hunger-satiety system in vivo.

Alpha-melanocyte stimulating hormone in ghrelin-elicited feeding and gut motility

This review evaluates published studies regarding alpha-melanocyte stimulating hormone (α-MSH) in ghrelin-elicited feeding and gut motility. We have sought to integrate all available evidences to provide a complete review on the properties of melanocortin receptors (MCR) and the potential clinical treatment of α-MSH after ghrelin-elicited feeding and gut motility. The available studies were grouped into four categories: food intake, gastric emptying, small intestinal transit, and colonic transit. As we describe, the literature provides evidence of the ability of ghrelin to increase food intake, gastric emptying, small intestinal transit, and colonic transit. α-MSH, which displays high affinity for the MC3 and MC4 receptors, can competitively activate MCRs with agouti-related protein stimulated by ghrelin, and partly attenuates the effect of acyl ghrelin on food intake. Central ghrelin-induced acceleration of gastric emptying is not mediated by MCRs, but the acceleration of the small intestinal transit is at least partly mediated via MCRs in the brain. Similar to fecal pellets and total fecal weight, distal colonic motility and secretion are partly mediated by MCRs in the brain. The interplay between acyl ghrelin and MCRs may provide a new therapeutic avenue to ameliorate anorexia and constipation.

The Long-Term Impact of High Levels of Alpha-Melanocyte-Stimulating Hormone in Energy Balance Among Obese Adolescents

Background: Deregulation of orexigenic and anorexigenic pathways occurs among adolescents with obesity. Alpha-melanocyte-stimulating hormone (α-MSH) is a key catabolic mediator of energy homeostasis and an important anorexigenic neuropeptide in the control of energy balance and thermogenesis. However, it was not well explored if α-MSH can modulate long-term weight loss therapy responses in a dependent manner according to its concentration. Our hypothesis is that a high α-MSH concentration at baseline promotes better modulation of anorexigenic/orexigenic pathways in obese adolescents. Methods: One hundred ten post-pubertal obese adolescents (body mass index >95th percentile) were submitted to 1 year of interdisciplinary therapy (clinical, nutritional, psychological, physical exercise, and physiotherapy support). Body composition and plasma levels of α-MSH, neuropeptide Y (NPY), melanin-concentrating hormone, and agouti-related peptide (AgRP) were measured before and after therapy. The volunteers were grouped on the basis of Tertiles of α-MSH concentration: Low (<0.75 ng/mL), Medium (≤0.76 to ≥1.57 ng/mL), and High (>1.57 ng/mL). Significance was set as p < 0.05. Results: The treatment promoted a significant improvement in body adiposity and fat free mass for all groups. It is important to note that only in the high α-MSH group, a significant increase of the α-MSH/NPY ratio and decrease NPY/AgRP ratio post treatment were observed. Conclusion: The high α-MSH concentration promotes better modulation of anorexigenic/orexigenic pathways in obese adolescents following long-term weight loss therapy and this is important in clinical practice.

Intrinsic and Antipsychotic Drug-Induced Metabolic Dysfunction in Schizophrenia

For decades, there have been observations demonstrating significant metabolic disturbances in people with schizophrenia including clinically relevant weight gain, hypertension, and disturbances in glucose and lipid homeostasis. Many of these findings pre-date the use of antipsychotic drugs (APDs) which on their own are also strongly associated with metabolic side effects. The combination of APD-induced metabolic changes and common adverse environmental factors associated with schizophrenia have made it difficult to determine the specific contributions of each to the overall metabolic picture. Data from drug-naïve patients, both from the pre-APD era and more recently, suggest that there may be an intrinsic metabolic risk associated with schizophrenia. Nevertheless, these findings remain controversial due to significant clinical variability in both psychiatric and metabolic symptoms throughout patients' disease courses. Here, we provide an extensive review of classic and more recent literature describing the metabolic phenotype associated with schizophrenia. We also suggest potential mechanistic links between signaling pathways associated with schizophrenia and metabolic dysfunction. We propose that, beyond its symptomatology in the central nervous system, schizophrenia is also characterized by pathophysiology in other organ systems directly related to metabolic control.