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

OBJECTIVE: The hypothalamus plays a crucial role in the regulation of feeding behavior. The anorexigenic neuropeptide alpha-melanocyte-stimulating hormone (α-MSH) and the orexigenic neuropeptide agouti-related protein (AgRP) are among the major peptides produced in the hypothalamus. This study investigated the plasma concentrations of α-MSH and AgRP in underweight and obese children and their healthy peers. The associations between α-MSH and AgRP levels and anthropometric and nutritional markers of malnutrition and obesity were also assessed. METHODS: Healthy sex-matched subjects aged 2 to 12 years were divided into 3 groups, as underweight (n=57), obese (n=61), and of normal weight (n=57). Plasma fasting concentrations of α-MSH and AgRP were measured by enzyme-linked immunosorbent assay. The differences between the three groups as to the relationships between plasma concentrations of α-MSH and AgRP and anthropometric data, serum biochemical parameters and homeostatic model assessment of insulin resistance were evaluated. RESULTS: Obese children had significantly lower α-MSH levels than underweight (1194±865 vs. 1904±1312 ng/mL, p=0.006) and normal weight (1194±865 vs. 1762±1463 ng/mL, p=0.036) children; there were no significant differences in the α-MSH levels between the underweight and normal weight children (p=0.811). Also, no significant differences were observed between the underweight and obese children regarding the AgRP levels (742±352 vs. 828±417 ng/mL, p=0.125). We found a significant positive correlation between plasma α-MSH and AgRP levels across the entire sample. CONCLUSION: This study is the first to demonstrate body weight-related differences in α-MSH and AgRP levels in children. Circulating plasma α-MSH levels in obese children were markedly lower than those of underweight and normal-weight children. This suggests that α-MSH could play a role in appetite regulation.

Role of circulating adipocytokines vaspin, apelin, and visfatin in the loss of appetite in underweight children: a pilot trial.

OBJECTIVES: To investigate serum concentrations of vaspin, apelin, and visfatin in underweight children and their association with anthropometric and nutritional markers of malnutrition. SUBJECTS AND METHODS: We recruited 44 underweight prepubertal children (youngest age = 2 years) with thinness grades of 1, 2, and 3, and body weights < 90% of ideal body weight due to loss of appetite and less frequent hunger episodes. Forty-one healthy age- and gender-matched controls were also included in the study. Serum fasting vaspin, apelin, and visfatin concentrations were measured by enzyme immunoassay technique. RESULTS: Mean vaspin and apelin levels were significantly lower in underweight children compared to controls (vaspin: 0.44 ± 0.18 vs. 0.58 ± 0.35 pg/mL, p = 0.024; apelin: 483.37 ± 333.26 vs. 711.71 ± 616.50 pg/mL, p = 0.041). Visfatin levels were lower in underweight children compared to controls, but the values were not statistically significant (177.81 ± 158.01 vs. 221.15 ± 212.94 pg/mL, p = 0.119). CONCLUSIONS: In underweight children, decreased vaspin and apelin levels should be considered in the etiology of anorexia.

Correlation of Brain Neuropeptide (Nesfatin-1 and Orexin-A) Concentrations with Anthropometric and Biochemical Parameters in Malnourished Children.

OBJECTIVE: Malnutrition continues to be a leading cause of stunted growth in many countries. This study aimed to investigate serum nesfatin-1 and orexin-A levels in underweight children and the potential correlations of these levels with anthropometric and nutritional parameters. METHODS: The study enrolled 44 prepubertal children (between 2 and 12 years of age) with thinness grades of 1-3 and 41 healthy age- and gender-matched children. The demographic, clinical and laboratory parameters including nesfatin-1 and orexin-A concentrations were compared between the two groups. The correlations of nesfatin-1 and orexin-A with biochemical and anthropometric parameters were investigated. The receiver operating characteristic (ROC) analysis were also performed for evaluating nesfatin-1 and orexin-A in distinguishing children with malnutrition from healthy controls. RESULTS: Thyroid-stimulating hormone, vitamin B12 and insulin levels were significantly lower in the study group than controls (p=0.001, p=0.049 and p=0.033, respectively). Mean nesfatin-1 levels in the malnourished group was also significantly lower compared to the healthy controls (3871.2 ± 1608.8 vs. 5515.0 ± 3816.4 pg/mL, p=0.012). No significant difference was observed in the orexin-A levels between the two groups (malnourished vs. control groups: 1135.7 ± 306.0 vs. 1025.7 ± 361.6 pg/mL, p=0.141). Correlation analyses revealed a positive correlation of nesfatin-1 and a negative correlation of orexin-A with body mass index (BMI) z-score. ROC analysis demonstrated that nesfatin-1 and orexin-A cannot be used to distinguish children with malnutrition from healthy controls (AUC: 0.620, p=0.061 for nesfatin-1 and AUC: 0.584, p=0.190 for orexin-A). CONCLUSION: The positive correlation of nesfatin-1 and the negative correlation of orexin-A with BMI suggest that these neuropeptides may be a part of a protective mechanism in the maintenance of nutritional status and that they may have a role in regulating food intake in undernourished children.