Changes in Nocturnal Leptin and Insulin Concentrations in Prepubertal Low Birth Weight Children after Administration of the IGF-I/IGFBP-3 Complex

Background: There is limited information regarding the effects of IGF-I and/ or IGFBP-3 on circulating leptin concentrations. Aim: To determine the effects of IGF-I on leptin and insulin concentrations, we examined leptin and insulin nocturnal profiles before and after the administration of the IGF-I/IGFBP-3 complex (Iplex (TM)) to prepubertal, low birth weight children. Methods: We studied 20 prepubertal children (11 boys and 9 girls), born after a full-term pregnancy with a mean birth weight below 2.8 kg. They were studied at the mean age of 7.3 +/- 0.5 years (range 4-11 years). Their mean height was -1.8 +/- 0.3 SDS and their mean BMI was 0.1 +/- 0.2 SDS at the time of the study. The children were studied on 2 separate occasions, the first under basal conditions, and the second time after s.c. administration of 1 mg/kg of Iplex (TM) at 21.00 h. Blood samples for determination of leptin and insulin were obtained every 60 min between 23.00 h and 07.00 h, while the children were sleeping. In each patient, we calculated the leptin and insulin mean area under the curve, both under basal conditions and after the administration of the IGF-I/IGFBP-3 complex. Results: Mean nocturnal leptin area under the curve exhibited a significant increase (2.7 +/- 2.1 vs. 11.2 +/- 2.6 ng/ml h, p < 0.05), whereas that for mean insulin showed a slight decrease, which did not reach statistical significance after administration of the IGF-I/IGFBP-3 complex. Conclusion: These findings indicate that administration of the IGF-I/IGFBP-3 complex increases circulating leptin concentrations in short prepubertal, small for gestational age children, suggesting that IGF-I and/or IGFBP-3 may stimulate leptin secretion by adipose tissue. Copyright (C) 2009 S. Karger AG, Basel