Ghrelin, Adipokines, Metabolic Factors in Relation With Weight Status in School-children and Results of a 1-year Lifestyle Intervention Program

Christine Rambhojan; Elodie Bouaziz-Amar; Laurent Larifla; Jacqueline Deloumeaux; Josiane Clepier; Jean Plumasseau; Jean-Marc Lacorte; Lydia Foucan

Disclosures

Nutr Metab. 2015;12(43) 

In This Article

Methods

Study Design

We performed a cross-sectional analysis of basal data and a prospective study to evaluate after 1 year, the changes in children profiles in Guadeloupe Island (FWI).

Study Population

In 2013, children from a middle school were invited to participate in the study. They were eligible if they were i) aged between 11 and 15 years, ii) affiliated to a social security scheme and iii) in good health conditions. Exclusion criteria included seizure disorders, diabetes, cardiovascular disease or pregnancy.

The study was approved by the Ethic Committee (South West - Overseas III, Bordeaux, France) in October 2012 and the French National Agency for Medecine and Health Products Safety Security (ANSM). Written informed consent, to participate in this study, was obtained from all children and parents.

Study Protocol

At baseline, anthropometric and biochemical measurements were carried out in all children and, children and accompanying parents fulfilled questionnaires on lifestyle.

We conducted a 1-year lifestyle intervention program including 1) a nutritional information session presented, at the start of the study, by a nutritionist explaining healthy eating and nutrient needs to children and parents 2) Information on health risks for diseases related to lack of exercise and overweight 3) Encouragement for reduction of sedentary behaviors 4) Advices to achieve five hours per week of school physical education and/or physical activity outside of school and 5) Participation of parents.

The school usually provided three hours per week of physical education, supervised by physical education teachers.

Phone calls were made to maintain adherence to the program and, in voluntary children, anthropometric clinical and biological parameters (except ghrelin concentrations) were evaluated after the 1-year lifestyle intervention.

Data Collection

Clinical and biological examinations were performed at the referring Health Centre of Guadeloupe (AGREXAM). Participants were interviewed by a research Engineer and physicians using standard questionnaires that provided information on age, sex, anthropometric measurements, lifestyle and use of treatments.

Anthropometric measurements were performed by trained nurses. Height in centimeters (cm) and weight in kilograms (kg) were measured with participants standing without shoes and lightly clothed. The body mass index (BMI) was calculated as weight/height2 (kg/m2). The standard deviation score of body mass index (BMI Z-score) was used to provide a standard indicator of relative adiposity[14] and was calculated as [(measured value – average value in the reference population)/standard deviation in the reference population] using a "Pediatric z-Score Calculator". Waist circumference (WC) in centimeters (cm) was measured in a standing position at the navel level at minimal respiration and the waist-to-height ratio (WHtR) was calculated.

Systolic and diastolic blood pressure (SBP and DBP, respectively) were assessed using automated monitors after resting for at least 5 min. The retained values were the average of two readings (left and right arms).

Pubertal stage was assessed according to Tanner.[15] Tanner stages 3, 4 and 5 defined pubertal/post-pubertal development.

Laboratory Measurements

Blood Sample Analysis. Blood samples were collected by venipuncture after an overnight fast. The biochemical analyses were performed in a single laboratory using the same methods.

Blood glucose level (mmol/L) was assessed using the glucose oxidase method. Serum lipid levels (mmol/L) were measured enzymatically.

Serum insulin levels (μIU/mL) were measured using the COBAS electro chemiluminescence immune assay test (Roche Diagnostics, Basel, Switzerland). The homeostasis model assessment to determined insulin resistance (HOMA-IR) was calculated using the following formula: [fasting insulin (μIU/mL) x fasting glucose (mmol/L)/22.5].[16]

Plasma samples were frozen at −80 °C until measurements of ghrelin, leptin and adiponectin and assayed in duplicate. Total ghrelin (ng/L) was measured with RIA kit Merck-Millipore® (EZGRT-89 K), leptin ng/mL and total adiponectin (μg/mL) were measured with ELISA kits Biovendor® (RD191001100) and Alpco® (47-ADPHUE-01) respectively. These measurements were made concomitantly for the samples collected at baseline and at one year (end of the study).

Definition of Factors

Weight status The children were classified according to the definition of overweight and obesity by the International Obesity Task Force (IOTF), that provide age and sex specific cut off points in childhood (from 2–18 years), predicting the accepted adult cut off points of a BMI of 25 and 30 kg/m2 (for overweight and obesity respectively).[17] The three categories were defined as follows: normal weight with BMI < IOTF-25 kg/m2, overweight with BMI ≥ IOTF-25 kg/m2 and BMI < IOTF-30 kg/m2 and obesity.with BMI ≥ IOTF-30 kg/m2.

Abdominal obesity in children was defined as WHtR greater or equal to 0.5.[18]

Blood lipid abnormalities was defined as HDL-cholesterol <1.03 or TG ≥ 1.7.[18]

Insulin resistance was defined by a HOMA-IR > 3.16.[19]

Statistical Analysis

Data are presented as numbers (percentages) for categorical variables and as means ± standard deviations (SD) for continuous variables. The chi-squared test and ANCOVA with adjustment for age, sex were used to test percentage and mean differences between the three groups. Non parametric tests were used for comparison between data at baseline and 1-year.

The Pearson correlation test was used to study the relationships between serum ghrelin, leptin, adiponectin concentrations and the other continuous variables.

We also used the multivariate linear regressions in the overall study population to evaluate the associations of serum ghrelin, leptin and adiponectin as dependent variables and age, gender, weight status, Tanner stage and HOMA-IR as independent variables.

The IBM SPSS Statistics software version 21 was used for data analyses. All tests were two-sided and a P value < 0.05 was considered significant.

processing....