ESPE Abstracts

Background/objectives: Individuals born small-for-gestational age (SGA), especially those who experience postnatal catch-up growth, are at increased risk for developing endocrine-metabolic abnormalities before puberty. In adults, brown adipose tissue (BAT) has been associated with protection against metabolic disorders, such as obesity, type 2 diabetes and dyslipidaemia. Here, we assessed for the first time whether BAT activation differs between prepubertal children born SGA or appropriate-for-gestational age (AGA).

Subjects/methods: The study population consisted of 86 prepubertal children (41 AGA and 45 SGA; age (mean±S.E.M), 8.5±0.1 yr), recruited into two prospective longitudinal studies assessing endocrine-metabolic status and body composition in infancy and childhood. The temperature at the supraclavicular region (SCR) before and after a cold stimulus was measured by infrared thermal imaging, and the area of thermally active SCR (increase after cold challenge, ΔArea_SCR) was calculated as a surrogate index of BAT activation. The results were correlated with clinical, endocrine-metabolic and inflammation variables, and with visceral and hepatic adiposity (assessed by MRI).

Results: No differences in BAT activation index, as judged by ΔArea_SCR, were found between AGA and SGA children. However, girls showed higher baseline and post-cold induction Area_SCR than boys (both p≤0.01). An interaction between gender and birthweight subgroup was observed for BAT activation so that AGA girls increased significantly the thermally active SCR after cold challenge as compared to AGA boys; this increase did not occur in SGA girls vs SGA boys. Cold-induced ΔArea_SCR negatively correlated with HOMA-IR, us-CRP, liver volume and liver fat.

Conclusions: As compared to SGA girls, prepubertal girls born AGA appear to have a surplus of BAT vs their gender counterparts, that is negatively related to central (ectopic) adiposity. Long-term follow–up of these cohorts will disclose whether those differences are maintained through puberty and relate to pubertal timing, to subsequent changes in liver volume and hepatic fat, and to the development of obesity and metabolic and cardiovascular disorders.